Designing castings for performance

© 2009 ASM International All Rights Reserved Casting Design and Performance (#05263G) www.asminternational.org Casting Design and Performance Materials Park, Ohio 44073-0002 www.asminternational.org © 2009 ASM International All Rights Reserved Casting Design and Performance (#05263G) www.asminternational.org Copyright # 2009 by ASM InternationalW All rights reserved No part of this book may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the written permission of the copyright owner First printing, November 2009 Great care is taken in the compilation and production of this book, but it should be made clear that NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING, WITHOUT LIMITATION, WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE GIVEN IN CONNECTION WITH THIS PUBLICATION Although this information is believed to be accurate by ASM, ASM cannot guarantee that favorable results will be obtained from the use of this publication alone This publication is intended for use by persons having technical skill, at their sole discretion and risk Since the conditions of product or material use are outside of ASM’s control, ASM assumes no liability or obligation in connection with any use of this information No claim of any kind, whether as to products or information in this publication, and whether or not based on negligence, shall be greater in amount than the purchase price of this product or publication in respect of which damages are claimed THE REMEDY HEREBY PROVIDED SHALL BE THE EXCLUSIVE AND SOLE REMEDY OF BUYER, AND IN NO EVENT SHALL EITHER PARTY BE LIABLE FOR SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES WHETHER OR NOT CAUSED BY OR RESULTING FROM THE NEGLIGENCE OF SUCH PARTY As with any material, evaluation of the material under end-use conditions prior to specification is essential Therefore, specific testing under actual conditions is recommended Nothing contained in this book shall be construed as a grant of any right of manufacture, sale, use, or reproduction, in connection with any method, process, apparatus, product, composition, or system, whether or not covered by letters patent, copyright, or trademark, and nothing contained in this book shall be construed as a defense against any alleged infringement of letters patent, copyright, or trademark, or as a defense against liability for such infringement Comments, criticisms, and suggestions are invited, and should be forwarded to ASM International Prepared under the direction of the ASM International Technical Book Committee (2008–2009), Lichun L Chen, Chair ASM International staff who worked on this project include Scott Henry, Senior Manager of Product and Service Development; Steven Lampman, Technical Editor; Ann Britton, Editorial Assistant; Bonnie Sanders, Manager of Production; Madrid Tramble, Senior Production Coordinator; and Diane Whitelaw, Production Coordinator Library of Congress Control Number: 2009935431 ISBN-13: 978-0-87170-724-6 ISBN-10: 0-87170-724-1 SAN: 204-7586 ASM InternationalW Materials Park, OH 44073-0002 www.asminternational.org Printed in the United States of America © 2009 ASM International All Rights Reserved Casting Design and Performance (#05263G) www.asminternational.org Contents Design Problems Involving Junctions 147 Design Problems Involving Distortion 155 Preface v Part I: Casting Design Principles and Practices Casting Design Issues and Practices Casting Design and Processes Modeling of Casting and Solidification Processing 37 Part II: Process Design Riser Design Gating Design Design for Economical Sand Molding Design for Economical Coring 61 73 81 89 Part III: Design and Geometry Casting Design and Geometry Design Problems Involving Thin Sections Design Problems Involving Uniform Sections Design Problems Involving Unequal Sections 101 121 133 139 Part IV: Casting Performance Corrosion of Cast Irons Corrosion of Cast Carbon and Low-Alloy Steels Corrosion of Cast Stainless Steels Fatigue and Fracture Properties of Cast Irons Fatigue and Fracture Properties of Cast Steels Fatigue and Fracture Properties of Aluminum Alloy Castings Friction and Wear of Cast Irons Friction and Wear of Aluminum-Silicon Alloys Failure Analysis of Castings Inspection of Castings 163 171 175 185 199 209 219 227 237 247 Appendix: Classification of Casting Defects 251 Index 259 iii © 2009 ASM International All Rights Reserved Casting Design and Performance (#05263G) www.asminternational.org © 2009 ASM International All Rights Reserved Casting Design and Performance (#05263G) www.asminternational.org Preface Component geometry is a powerful aspect of casting design in terms of both effective production and the function of a cast part Many tools have been developed for casting design, and the examples of past designs, even those of years ago, provide an important baseline in producing effective castings Computer modeling and simulation has greatly facilitated the design process, and the article “Modeling of Casting and Solidification Processing” provides an extensive review of the subject In addition, the complex aspects of configuration design are detailed in a series of articles in the sections on “Process Design” and “Design and Geometry.” Several of these articles are based on the ASM publication Casting Design Handbook (1962), which has been out-of-print for many years Nonetheless, the lessons are still relevant today, as the basic fundamentals of geometry, metallurgy, and physics remain unchanged (even within the view of new modern perspectives and the advent of more powerful analytical or numerical tools) It is noted that the distinct sections on “Process Design” and “Design and Geometry” are a somewhat artificial division of topics, because really both process and design are intertwined in complex ways, especially for castings In a sense, the “design” is like the fulcrum that leverages these two important aspects of castings into effective products It is hoped that this collection of articles provides a useful reference on casting design Finally, the performance of cast products is covered in a series of articles in the last section Ultimately, the performance of product determines its success S Lampman February 2009 v ASM International is the society for materials engineers and scientists, a worldwide network dedicated to advancing industry, technology, and applications of metals and materials ASM International, Materials Park, Ohio, USA www.asminternational.org This publication is copyright © ASM International® All rights reserved Publication title Product code Casting Design and Performance 05263G To order products from ASM International: Online Visit www.asminternational.org/bookstore Telephone 1-800-336-5152 (US) or 1-440-338-5151 (Outside US) Fax 1-440-338-4634 Mail Customer Service, ASM International 9639 Kinsman Rd, Materials Park, Ohio 44073-0002, USA Email CustomerService@asminternational.org American Technical Publishers Ltd 27-29 Knowl Piece, Wilbury Way, Hitchin Hertfordshire SG4 0SX, In Europe United Kingdom Telephone: 01462 437933 (account holders), 01462 431525 (credit card) www.ameritech.co.uk Neutrino Inc In Japan Takahashi Bldg., 44-3 Fuda 1-chome, Chofu-Shi, Tokyo 182 Japan Telephone: 81 (0) 424 84 5550 Terms of Use This publication is being made available in PDF format as a benefit to members and customers of ASM International You may download and print a copy of this publication for your personal use only Other use and distribution is prohibited without the express written permission of ASM International No warranties, express or implied, including, without limitation, warranties of merchantability or fitness for a particular purpose, are given in connection with this publication Although this information is believed to be accurate by ASM, ASM cannot guarantee that favorable results will be obtained from the use of this publication alone This publication is intended for use by persons having technical skill, at their sole discretion and risk Since the conditions of product or material use are outside of ASM's control, ASM assumes no liability or obligation in connection with any use of this information As with any material, evaluation of the material under end-use conditions prior to specification is essential Therefore, specific testing under actual conditions is recommended Nothing contained in this publication shall be construed as a grant of any right of manufacture, sale, use, or reproduction, in connection with any method, process, apparatus, product, composition, or system, whether or not covered by letters patent, copyright, or trademark, and nothing contained in this publication shall be construed as a defense against any alleged infringement of letters patent, copyright, or trademark, or as a defense against liability for such infringement Casting Design and Performance Pages 18 Copyright â 2009 ASM Internationalđ All rights reserved www.asminternational.org Casting Design Issues and Practices* H.W Stoll, Northwestern University DESIGN is the critical first step in the development of cost effective, high quality castings Designing a successful casting requires an integrated, concurrent engineering approach It also requires systematic and structured use of sophisticated computer-aided design software and casting analysis and simulation software In this paper, we discuss these and other issues impacting good casting design In particular, design decisions that drive casting performance and cost are identified and used as the basis for a proposed holistic approach to casting design This new design philosophy and methodology is aimed at optimizing both the structural performance and producibility of the casting while minimizing design time and effort In casting, the part being produced and the tooling used to produce the part interact in complex ways, which effect both the quality and cost of the casting This suggests that the design of a successful casting requires an integrated approach that considers both functional and process requirements simultaneously In the traditional setting, however, the design engineer typically first decides the geometry of a casting and then a casting engineer independently develops the mold and process This decoupled arrangement often results in more costly castings with larger safety factors than necessary In addition, lead times for casting development using this approach can be excessive As manufactures seek to reduce weight and cost of products, casting has re-emerged as the manufacturing process of choice in many situations This is because casting offers the important advantage of being able to produce highly complex functional shapes quickly and easily Cost is reduced because numerous parts and complex construction and processing typically associated with built up structures and weldments can be replaced by a single cast part Weight is reduced because material can be distributed to where it is needed and because sections can be thinner since load does not transfer across part interfaces (i.e., through fasteners or welds) To take advantage of these unique capabilities, castings must be properly conceived and designed from the start This means that design engineers and casting engineers will need to change the casting design and development process from the historical sequential, decoupled approach to a more integrated and concurrent approach This new approach must be based on the recognition that the part geometry not only affects the load carrying functionality of the casting, but also the mold construction, mold filling and material solidification processes involved in producing the casting These processes in turn affect cycle time, casting quality, and material properties such as yield strength, ultimate strength, and fatigue resistance Casting geometry must therefore be determined based on both functional and processing requirements Hence, design engineers must become more knowledgeable of the casting process, and casting engineers must have a better understanding of the functional requirements that drive the design In essence, the new design philosophy must not only facilitate good part and process design, it must also teach it This paper discusses the issues and practices associated with good casting design The focus of the paper is on casting design in general, and on sand and permanent mold aluminum casting in particular We begin by examining the casting design process from a variety of design and processing perspectives Strategies for casting design process improvement are then proposed which provide the basis for a new casting design philosophy and methodology Two possible implementations are presented The first is a structured team approach that is intended as a possible means for quickly improving traditional casting design practice by integrating the casting geometry and process design The second is a longer-term approach involving the development of casting design guidelines for the design of lightweight, high quality, and high performance structural castings Geometry/Material/Process Interactions Carefully planned geometry is the secret to efficient load carrying capacity and acceptable component performance It is also the secret *Reprinted from Proceedings from Materials Solutions Conference ’98 on Aluminum Casting Technology for achieving high quality (i.e., uniform properties, soundness, etc.) and for avoiding costly and time consuming problems associated with pouring and solidification of the alloy Understanding how casting geometry, the material in both its liquid and solid phases, and the casting process interact provides the insight needed to specify the best casting geometry from a function, form, and fabrication point of view In the following, we explore several geometry/ material/process interactions that are pivotal to good casting design Much of this discussion is based on the paper “Cost Effective Casting Design — Developing a Conceptual Framework for Designing Metal Castings” by Michael Gwyn (Ref 1) The reader is referred to this paper for a more in-depth discussion of many of the topics briefly referred to here Fluid life is the ability of the molten alloy to fill the mold cavity, flow through thin narrow channels to form thin walls and sections, and conform to fine surface detail In addition to temperature of the molten metal, fluid life also depends on chemical, metallurgical, and surface tension factors Therefore, the fluid life of each alloy is different For example, aluminum 356 is considered to have excellent fluid life whereas the fluid life of aluminum 206 is only fair to good Fluid life determines the minimum wall thickness and maximum length of a thin section It also determines the fineness of cosmetic detail that is possible Hence, knowing that an alloy has limited fluid life suggests that the part should feature softer shapes (i.e., generous radii, etc.), larger lettering, finer detail in the bottom portion of the mold, coarser detail in the upper portions of the mold, more taper leading to thin sections, and so forth Solidification Shrinkage Shrinkage occurs in three distinct stages: liquid shrinkage, liquid-to-solid shrinkage, and solid shrinkage Liquid shrinkage is the contraction of the liquid before solidification Liquid-to-solid shrinkage or solidification shrinkage is the shrinkage that occurs as the liquid’s disconnected atoms and molecules form into the crystals of atoms and chemical compounds that comprise the solid metal Solid shrinkage is the shrinkage that occurs as the solid metal casting cools to / Casting Design and Performance ambient temperature Although liquid shrinkage is important to the metal caster, it is not an important design consideration Solidification shrinkage and solid shrinkage, on the other hand, are extremely important and must be carefully considered during casting design Different alloys have differing amounts of liquid-to-solid shrinkage (e.g., aluminum 356 has little while aluminum 206 has moderate to large) Most importantly, there are three different types of solidification shrinkage: directional, eutectic, and equiaxed In alloys such as malleable iron and carbon steel, which solidify directionally, solidification moves along predictable pathways determined by the casting geometry and thermal gradients in the mold For example, solidification will typically begin at the mold wall and move perpendicularly toward the center of the part This is called progressive solidification Solidification will also begin in cooler regions where the mold surface area to metal volume ratio is large and travel toward the hotter regions of the casting This is called directional solidification The key is to configure the part geometry so that directional solidification can occur before progressive solidification shuts off the source of liquid metal supply (the riser) Without proper pathway geometry (e.g., risering and tapering), voids or pores due to isolated internal shrinkage can result In eutectic-type solidification, the liquid metal cools and then solidifies very quickly all over This behavior minimizes internal shrinkage and the need for risers and makes this type of alloy the most forgiving of the three Eutectic-type materials that have very little solidification shrinkage like gray iron often require no risering at all The key geometric concern for eutectic-type solidifying alloys like aluminum 356 which have small but appreciable solidification shrinkage is to ensure that the avenue of liquid metal supply stays open and functioning all the way to final solidification In addition to solidifying both progressively and directionally from the mold walls, alloys that exhibit an equiaxed solidification behavior also begin to solidify throughout the liquid, forming mushy regions consisting of equiaxed islands of solid These equiaxed islands can block the avenues of liquid metal supply making these alloys difficult to feed To offset this tendency, regions that solidify in an equiaxed-type manner should be designed to have small thermal gradients, that is, to be as thermally neutral as possible Therefore, thermal mass in these regions should be spread out and distributed uniformly throughout the region This causes the shrinkage to be distributed as microscopic pores throughout the volume of the casting Although the thought of having microscopic holes in the casting is disturbing, the effect on mechanical properties is greatly minimized by the small size, rounded shape, and uniform dispersion produced by using the proper geometry for this type of alloy Also, a uniform dispersion of very small pores is clearly preferable to large, irregular pores concentrated in possibly critical regions of the casting that could result from less appropriate part geometries Solid shrinkage is often called pattern maker’s shrink because the tooling must be properly sized so that the part will shrink to the desired final size and shape upon cooling Solid shrinkage is critical for two important reasons First, the shrinkage must be predicted and then built into the patterns/dies and corebox dimensions If this is not done correctly, then the tooling will need to be modified iteratively to achieve an acceptable production casting This adds time and cost to the design cycle and introduces quality risk in the final product Second, as the casting cools, it may not be able to shrink uniformly because some regions are stiffer than others This can result in undesirable residual stresses and/or undesirable warpage Creating geometry’s that make shrinkage predictable and that avoid residual stress and warping is therefore highly desirable Slag/Dross Formation Slag is typically composed of liquid nonmetallic compounds (usually fluxed refractories), products of alloying, and products of oxidation in air Dross refers to nonmetallic compounds produced primarily by the molten metal reacting with air Some molten metal alloys are much more sensitive to slag/dross formation than others Castings made from these alloys are much more likely to contain nonmetallic inclusions In addition to process and quality control techniques, part geometry can be used to dramatically reduce the likelihood of nonmetallic inclusions For example, for castings made from alloys that have buoyant slag/dross, the probability of having an inclusion in a critical machined surface can be reduced by designing the part so those surfaces are in the lower portion of the mold Similarly, rigging design (i.e., configuration of sprues, runners, and gates) can be designed to control the amount of oxidation that occurs due to turbulent flow and entrained air Pouring Temperature Molds used in the casting process must withstand the extremely high temperature of molten metal Often, proper casting geometry can help make the mold robust against this thermal abuse Also, recognizing the undesirable effects of high pouring temperature on casting quality can help For example, high pouring temperatures can lead to poor as-cast surface finish due to metal penetration into small sand cores Therefore, when pouring temperature is high, it is often advisable to machine rather than core small holes and other small features Fluid Flow Another key geometry/process interaction involves the flow of molten metal into the mold cavity As mentioned previously, turbulent flow through gates and other channels can effect the amount of oxidation and consequent dross formation that occurs Another consideration is the force generated by the molten metal as it flows into the mold cavity and the turbulence of the flow in the cavity since both of these effects can displace cores and erode mold walls, especially sharp edges and high detail features Steep thermal gradients can also arise due to fluid flow If the flow separates to pass around cores and other features and the joins together again, weld lines, nonmetallic inclusions, and other flaws can occur due to cooling and oxidation of the flow front In order to minimize undesirable effects of fluid flow, the casting must be poured slowly Unfortunately, this gives the molten metal more time to oxidize and increases process cycle time Undesirable interactions due to fluid flow effects can often be reduced or eliminated by designing the casting geometry and rigging as a system Heat Transfer Considerations The geometry must also be selected with an understanding of the heat transfer conditions involved High pouring temperatures mean that large amounts of heat must be transferred into the mold If the geometry is such that the heat cannot escape, a hot spot is likely to occur For example, narrow peninsulas or tight corners of mold material surrounded by molten metal will get hot very quickly and as a result, solidification of the molten metal in these regions will be slower than surrounding regions This creates the possibility of hot tears or shrinkage pulls because the hotter material will have less tensile strength and is therefor less able to resist internal forces that develop due to solidification and solid shrinkage Voids can also form because liquid metal supply paths close off before the material in the region of the hot spot is fully solidified Just the opposite situation occurs when sharp corners or narrow peninsulas of molten metal are surrounded by mold material In these cases, the molten metal cools and solidifies very quickly This is generally a desirable situation However, if cooling is too rapid, it can cause cold cracking due to stressing of the solidified skin or thin region by solidification shrinkage occurring at a slower rate in more massive adjacent regions Also, difficult to machine or undesirable material properties may result from to rapid cooling of some alloys Geometry/Alloy Interactions In most cases, it is the combination of material properties possessed by a particular alloy that determines the most desirable casting geometry For example, gray iron has a moderately high pouring temperature, excellent fluid life, and very small, eutectic type solidification shrinkage As a result, accept for the danger of hot spots due to its relatively high pouring temperature, gray iron is very casting friendly It’s excellent fluid life permits fine detail and thin sections and its low solidification shrinkage provides considerable geometry latitude Aluminum 356 has a low pouring temperature, excellent fluid life, and more eutectic type than directional type solidification The low pouring temperature makes it an excellent candidate for precision castings Also, its excellent Casting Design Issues and Practices / fluid life permits fine detail and thin walls everywhere However, although still relatively small, solidification shrinkage is significant enough to warrant consideration especially with respect to risering, section size, and feeding pathways Also of concern is the sensitivity of aluminum to dross formation Dross can be a particular problem because the specific gravity of aluminum oxide is close to that of molten aluminum and hence buoyancy does not aid separation Carbon steel is at the opposite end of the spectrum Steel has a very high pouring temperature, poor fluid life, and large, directional type solidification shrinkage This combination of material properties makes steel very casting unfriendly As a result, careful attention to casting geometry is essential Because of its poor fluid life and high pouring temperature, fine detail and thin sections are difficult Most importantly, because of its large solidification shrinkage, feeding of the casting is a great concern Risers need to be large and the geometry must be carefully designed to ensure proper feeding of the casting Because of its unfavorable combination of properties, steel and materials like it, require softer shapes (i.e., large radii, rounded shape, large lettering, no sharp detail) compared to casting friendly materials such as gray iron Cost Drivers A second way to look at the design of a casting is to understand how design decisions regarding casting geometry drive total cost of the casting By total cost, we mean the sum of all costs, both the direct and indirect, that result from the design, production, distribution, use, and salvage of the casting over its lifetime Although all components of total cost are important, we are particularly concerned in this paper with how design decisions drive both the direct cost associated with production of the casting and the cost of designing, building, and proving out the tooling This cost can be calculated on a per unit basis as follows, CT C0 tcycle Cost ẳ ỵ Cc ỵ V Cm ỵ ỵ Cs N Y (Eq 1) where: CT = total tooling cost ($) N = lifetime number of castings CC = cost of coring ($/unit) V = total casting volume (in3) Cm = alloy cost ($/in3) C0 = casting equipment and labor cost ($/hr) tcycle = total casting lead time (hr) Y = yield (useable castings/N) Cs = cost of secondary processing ($/unit) It is important to note that total tooling cost (CT) includes all cost associated with tooling including the cost of pattern and corebox construction, the cost of producing and inspecting the first article, and the cost of iteratively modifying the tooling to meet specifications Also, material volume (V) includes not only the volume of the casting, but also the volume of the risers, runners, and sprues used to feed the casting Total casting cycle time (tcycle) is given by the following, tcycle ẳ tnp ỵ tbuild ỵ tcast ỵ tcool ỵ ttrim (Eq 2) where: tnp = non-productive time (hr) tbuild = mold build time including core placement (hr) tcast = time to pour the casting (hr) tcool = time to cool to ambient temperature (hr) ttrim = time to remove gates, risers, etc (hr) Since many castings involve more than one core, the per unit cost of coring (CC) is calculated as, Cc ¼  nc  X C00 t0cycle V Cm ỵ YC i iẳ1 (Eq 3) where: nC = number of cores V0 = volume of core material (in3) = cost of core material ($/in3) Cm C0 = core making equipment and labor cost ($/hr) tcycle = core making cycle time (hr) YC0 = yield (useable cores/lifetime number of cores) Similarly, secondary processing may involve more than one process such as machining, heat treating, welding, painting, and plating In addition, processes such as machining might involve several different operations (e.g., drilling, milling, grinding, etc.) The per unit cost of secondary processing is therefore calculated as Cs ¼  ns  X C000 t00cycle CT00 ỵ YS00 i iẳ1 (Eq 4) where: ns = number of secondary processes CT00 = secondary process tooling cost ($/unit) C000 = secondary process equipment and labor cost ($/hr) 00 tcycle = secondary process cycle time (hr) YS00 = secondary process yield (useable castings/N) Equations through are very clear as to what should be done to reduce the per unit production and design cost:      Design to minimize tooling cost Design to minimize material cost Design to minimize process cycle time Design to maximize yield Minimize the number of cores and secondary processes By looking at how geometry decisions effect the sources of cost in the above equations, it is possible to make geometry decisions that reduce cost For example, both tooling cost and production cost will be reduced by selecting the parting plane early in the design and then creating geometry that minimizes the number of undercuts and other features that must be cored Locating riser and gate contacts at easy to access areas on the casting will reduce trimming time Also, locating riser and gate contacts so that they don’t interfere with machining fixture targets will reduce trimming time, the cost of the fixture, and possibly machining cycle time because fixturing will be easier and more consistent Designing so that critical dimensions not cross the parting line will decrease build time and increase yield since the positional accuracy required between the cope and drag is reduced Shape Optimization Metal casting offers two unique and very desirable design advantages: (1) metal mass can be located exactly where it is needed and (2) complex, three-dimensional geometry is readily created By properly capitalizing on these advantages, part geometry can be created that minimize both weight and cost of the part For example, the use of continuously varying section geometry that fully utilizes the material strength while also satisfying deflection requirements is readily achievable In addition, many parts can be consolidated into one part, thereby eliminating piece part fabrication cost, assembly cost, and all the indirect costs, interfacing information, quality risk, and manufacturing complexity associated with built-up parts and weldments Shape optimization is the design perspective that seeks to leverage these advantages This practice has been greatly facilitated by the development of powerful engineering workstations and solid modeling software that significantly enhances the engineer’s ability to visualize complex three-dimensional geometry and to analyze stress levels and deflections of complex three-dimensional shapes Rigging System Design The rigging system includes the system of sprues, runners, gates, risers, and chills that channel and control the flow of liquid metal into the mold cavity, feed the casting as it solidifies, and control the heat transfer and rate of solidification in critical regions Rigging system design specifies the size, dimensions and location of sprues, runners, gates, risers, and chills that comprise the system In the traditional approach, an expert casting engineer designs the rigging system, usually after the geometry of the casting has been specified Rigging design decisions typically include selection of the following: orientation of the cast part, parting line, potential sites for chills and chill types, sprue height and location, runner types and configuration, ingate sites, choke area (smallest cross-section area present in the flow system), riser sites and configuration, and pouring rate and temperature / Casting Design and Performance Casting Process Simulation In casting process simulation, comprehensive modeling of the intended production process is performed in order to determine the size and shape of sprues, runners, gates, and risers A variety of simulation software for performing this type of simulation is available In addition, methodologies have been developed to understand and predict the size and location of process related defects (microporosity, etc.) See for example references [2–6] Using these methodologies, the rigging system design can be varied in the foundry system simulation to evaluate how defect size and location are to be controlled and/or eliminated Using computer simulation early in the design process can greatly reduce the amount of guess work involved in specifying cost effective and functionally acceptable casting geometry Computer based casting process simulation offers two important advantages: (1) design iterations and what-if analysis are much easier to perform and (2) the physics engine underlying the simulation software provides a consistent and predictable science base for casting design This allows the casting geometry and rigging system to be specified and optimized as a coordinated system Most importantly, it allows evaluation of the overall design before tools are cut and the design is irreversibly committed to hardware When used properly, the result is a substantial reduction in design time and tooling iterations It is extremely important to note however, that the use of casting process simulation software is not, in itself, a viable substitute for early input of experienced tooling and foundry engineers Rather, it is a very powerful tool that helps leverage and assist the team approach Casting Design Improvement Strategies Casting design is an iterative process (Fig 1) The problem of design is typically formulated in terms of functional requirements and constraints that must be satisfied Functional requirements relate to the functions the part must provide while constraints relate to the form (shape, size, surface finish, precision, etc.) and processing (parting line, draft, section thickness, etc.) requirements that constrain the geometry that can be selected Based on the problem formulation, an initial design is created This design is then evaluated and modified iteratively until an acceptable design is achieved Typically, the redesign is guided by the design information, insight, and understanding developed in the evaluation step To be acceptable, the design must satisfy all functional requirements and constraints When the traditional approach to casting design is examined, we see that the iterative process characterized by Fig is essentially repeated at least two and perhaps several times as shown in Fig First the design engineer goes through the iterative design process to specify the casting geometry This geometry is then passed on to the casting engineer who repeats the iterative design process to specify the rigging system and apply pattern maker shrink to the casting dimensions Problems discovered during rigging system design can generate additional iterations if casting geometry changes are required Additional iterations to the casting geometry and rigging system design may also be required during tool fabrication and preparation for production of the first article Finally, iterative changes to the tooling and perhaps the casting and rigging system geometry may be necessary to tweak the design to meet production requirements Excessive design iterations can adversely impact the casting design in two important ways First, design iterations significantly increase design cost and time Second, design iterations, especially those performed late in the process, can lead to suboptimal design The result is a casting that falls short of cost, weight, and performance targets Such designs give casting a bad reputation and are a disappointment to all concerned Several strategies for improving the traditional casting design process are possible based on the design perspectives discussed above These are summarized as follows: Design the casting geometry and casting process as a coordinated system by integrating shape optimization and rigging system design into one concurrent process Consider geometry, material, and process interactions Fig Iterative model of the design process Fig Traditional casting design process and design related cost drivers from the beginning as part of the process Develop a thorough understanding of all customer needs including downstream processing constraints before beginning the design Focus on creating an acceptable initial design By spending the time up-front to create the best possible initial design, a large number of lengthy analyze-redesign iterations are avoided The evaluation phase should confirm the design rather than create it Use casting process simulation and other modern computer-aided analysis and inspection methods to quickly optimize the design Develop a consistent, well defined science base for casting design in the form of casting design guidelines and structured methodologies The goal of these strategies is to shorten the design cycle and help ensure that the best possible casting design is created In the sections that follow, we propose some possible approaches for implementing these strategies Structured Team Approach Strategies through 3, and to some extent, strategy can be implemented very easily and quickly by adopting a structured team approach By a structured team approach, we mean that the casting design is performed using a multi-disciplinary team and a structured design methodology The goal of the team approach is to have all required product and process knowledge available when the key early design decisions are being made In a structured design methodology, the overall problem of design is broken down into a series of sequential, easier to perform steps that proceed from the general to the specific Excessive iteration and long design times are avoided by performing each step in a thorough and disciplined manner In general, each step in the process can be further subdivided into steps to create a hierarchy of structured methodologies To illustrate the structured team approach, we propose the simple methodology shown schematically in Fig This approach recognizes that not all members of the team can be available for designing the casting on a continuous basis Team meetings are therefore scheduled at which all salient aspects of the design are reviewed and discussed All members of Failure Analysis of Castings / 241 Data Analysis and Report Preparation On completion of the material evaluation a thorough analysis of the background information, preliminary examination, and the test results must be conducted The test results should show a correlation with the casting process and the manufacturing operations It is important to keep an open mind and “let the data tell the story about the casting.” The “picture” of the failure should include all the pieces of the puzzle provided by the data If any data or piece of information does not fit into the picture or description of the failure, then an improper conclusion can be drawn and further information or data are needed to make sense of the results In most cases, the simplest explanation of the data is the best solution to the failure analysis problem Often, very minor details are very important and must be explained in the conclusion It should also be remembered that arriving at the wrong conclusion could be worse than having no conclusion It is also important that there are sufficient data to come to a conclusion If the information is inconclusive, or only partly explains the situation, then this should be stated All failure analysis projects should conclude with a report that summarizes the background information, the results of the preliminary studies and the material tests, and the conclusions of the study The scope of the report can range from a short summary statement to a very detailed presentation of the data It is important to present the data in a logical and clearly written manner, so that the reader can follow the test plan Typically, the data are presented with only a basic interpretation of the information in the body of the report The detailed discussion and interpretation of all of the data should be in a separate section It is important to separate facts from speculation Different analysts may draw different conclusions from the same results Therefore, the report writer should first present the data and then provide an interpretation of the findings Casting Fracture Characteristics The characteristics of casting fractures are, in general, similar to those of wrought alloys, but in many cases can be more complex When examining fractures in castings it is important to fully understand the fundamentals of fracture mechanisms and the basic fracture modes that are typical for the alloy involved As noted, it is important to know basic information about the part Background data concerning the alloy type and grade, the expected mechanical properties, the overall heat treatment, and any special surface treatments or processes should be obtained It is also essential to know the history of the part Did the fracture occur during the manufacturing process or when the part was in service? It is important to understand the loads applied to the part as well as the operating environment This background information can provide some insight into the expected fracture characteristics Examination Methods The evaluation of a failed casting must include visual inspection of the whole part and other related components as well as the actual fracture The part should be examined thoroughly to evaluate both the overall features and any unusual features Details such as surface damage, distortion, machining marks, fretting, corrosion deposits, and so forth all provide information about the environment and relationship to other components The examination of the fracture should be done using good illumination to see the fine details of the surface Oblique illumination should be used to evaluate the texture and profile of the fracture This type of illumination will help determine the location of the fracture origin The visual inspection should be conducted both prior to and after cleaning or removal of surface contamination The fracture should be examined with an optical or digital microscope at the critical regions of the origin, midfracture, and final fracture regions This may allow detection of any casting flaws In some cases the fracture origin can be at a subsurface anomaly, such as gas/shrinkage porosity, a nonmetallic inclusion, or anomalies from weld repair The precise location of crack initiation may only be discernible with aid of an optical/digital microscope In order to determine the fracture mode, which is how the casting broke, the critical regions of the fracture should be examined with a scanning electron microscope (SEM) The fine details that are characteristic of ductile rupture, transgranular brittle fracture, intergranular fracture or fatigue, and even some flaws, are not discernible with the unaided eye or with the optical/digital microscope These features can only be properly observed when examined at magnifications above approximately 500 The SEM allows routine examinations at magnifications up to 10,000 Regions of Interest The primary objective of the visual inspection is to determine the location of the fracture origin and evaluate how the crack propagated through the alloy Knowing where it started and where it ended provides information about how the part was loaded The origin region should be examined to determine where the crack initiated Did the crack start at a single point or over a broad area? Cracks typically originate at a site of stress concentration such as a surface anomaly, grinding marks, cast or machined notch, or subsurface flaw The mid-fracture region exhibits features that indicate how the crack propagated through the material This gives insight as to whether the part was subjected to cyclic, tensile, or torsional loading The edges of the fracture can exhibit slant fracture, or shear lips, that can help identify the origin region This is especially true for cast steels Factors That Affect Fracture Appearance The fracture texture at the origin region can have features that indicate where the crack started With overload fractures, steel castings will typically exhibit a chevron pattern that will point back to the origin region, as shown in Fig 1, whereas aluminum castings can exhibit a relatively rough texture in the origin region and a smoother texture at the other side of the broken section This is especially true when there is no distinct stress raiser in the origin region of the aluminum part With fatigue fractures, most cast alloys will exhibit thumbnailshaped beach marks or arrest lines that fan outward from the origin region The fracture surface texture of cast components can exhibit a different texture compared to a similar wrought product With some alloys, such as die-cast aluminum and improperly controlled gray or ductile iron, the near-surface region can have a chill zone that will exhibit a fine, smooth fracture texture Away from the surface the fracture may expose various anomalies such as shrinkage or gas porosity and nonmetallic inclusions in the form of sand, dross, slag, or reoxidation products Fatigue fractures can exhibit a rougher texture as the crack propagates through and around the anomalies With heavy-section steel castings in the quench and tempered condition, alloy segregation can cause varying degrees of both ductile and brittle fracture due to differences in the proportion of martensite and bainite Weld repairs can have a significant influence on the potential for crack initiation, at the surface or at subsurface regions Residual stresses Overload fracture through a low-alloy steel casting Courtesy of Stork Technimet, Inc New Berlin, WI Fig 242 / Casting Design and Performance Cast components typically exhibit the usual characteristics of ductile overload, such as necking and distortion, a dull fibrous fracture with little branching, and shear lips On examination at high magnification, ductile rupture typically exhibits dimples, which are formed by micro-void coalescence (MVC) Nucleation typically occurs at nonmetallic inclusions or second-phase particles Carbon, low-alloy, and stainless steel castings will typically exhibit classical dimples A low-alloy steel in the quench and tempered condition is shown in Fig A similar fracture mode can occur in a ductile iron, but the appearance is altered due to the presence of the nodules, which provide sites for MVC, as shown in Fig Dimples formed around the nodules The size and shape of the dimples is controlled by the nodule count and nodularity Ductile rupture in cast silicon-aluminum alloys can have different characteristics, depending on the heat treatment of the alloy In the as-cast condition, the primary and eutectic silicon can have an angular and flakelike structure Rupture through the alloy will occur at and through the silicon particles and also through the aluminum matrix The fracture will exhibit brittle features at the silicon particles, but tear ridges and dimples will be present at the matrix These features are illustrated in Fig 4, which shows the fracture through a type 380.0 die-cast aluminum component The larger the primary and eutectic silicon particles, the smaller the proportion of ductile features will be Heat treatment of a similar alloy would cause spheroidization of the silicon particles These silicon particles would provide sites for MVC, and the fracture would exhibit dimples, as shown in Fig The ductility, as measured by the percent elongation during tensile testing, would be substantially higher for a fully spheroidized alloy, and this correlates with the fracture appearance Ductile rupture in a low-alloy steel casting Original magnification: 3000 Courtesy of Stork Technimet, Inc New Berlin, WI Overload fracture through a type 380.0 aluminum alloy in the as-cast condition Original magnification: 1000 Courtesy of Stork Technimet, Inc New Berlin, WI Ductile rupture in a ductile iron Original magnification: 150 Courtesy of Stork Technimet, Inc New Berlin, WI Overload fracture through a type 356.0 aluminum alloy in the T6 condition Original magnification: 500 Courtesy of Stork Technimet, Inc New Berlin, WI from weld repair and improper grinding as well as rough finishing and carbon arc gouging can cause crack initiation Incomplete removal of casting defects and weld anomalies, such as slag, shrinkage cracks, or cracks from improper weld process control have been found to cause failures in steel castings Ductile Rupture Fig Fig Fig Fig Transgranular Brittle Fracture Transgranular brittle fracture in cast components typically exhibits the usual characteristics of brittle overload, such as little or no distortion, flat fracture, bright crystalline appearance, and a chevron pattern that points to the origin Examination at high magnification will show cleavage fracture through the grains The transgranular fracture is related to the nilductility transition temperature (NDTT) of the alloy, the strain rate, or brittle phases in the microstructure As with wrought products, the NDTT may be shifted to a temperature above the operating temperature of the component This can occur with carbon and low-alloy steels as well as ductile iron An example of cleavage fracture in a ductile iron is shown in Fig This contrasts with the ductile rupture features shown previously In some cases, such as ductile iron and low-alloy steel, the fracture may exhibit a mixture of both cleavage fracture and ductile rupture A typical example of a mixed fracture mode is shown for a low-alloy steel casting in Fig In some cases, the cleavage fracture is associated with the pearlite and the ductile rupture with the ferrite in the microstructure Cleavage fracture in a heavy-section ductile iron casting Original magnification: 200 Courtesy of Stork Technimet, Inc New Berlin, WI Fig Mixture of cleavage fracture and ductile rupture (arrows) in a low-alloy steel casting Original magnification: 1000 Courtesy of Stork Technimet, Inc New Berlin, WI Fig Failure Analysis of Castings / 243 It is important to be aware of the microstructure of the material, as the chill zone of a ductile iron can exhibit brittle features when the fracture extends through the iron carbides in the iron The example presented in Fig is from the same casting shown in Fig 3, but from a region that was chilled during solidification and cooling Another example of how the microstructure of an alloy can significantly influence the features of a fracture is gray iron Gray iron is typically considered to be a brittle material as the fracture surface exhibits the characteristic macrofeatures of a brittle alloy Examination at high magnifications shows that the fracture through a gray iron is primarily through and at the graphite flakes Only scattered rupture through the matrix occurs between the large flakes Therefore, the fracture will exhibit smooth curved surfaces that replicate the texture of the graphite, and only isolated locations with either cleavage or ductile rupture, as shown in Fig It is important to be aware that carbon and low-alloy steels can often exhibit quasi-cleavage If cast steel is properly quenched and tempered to form a microstructure of tempered martensite, the fracture will typically exhibit dimples, which are indicative of ductile rupture If the casting is not quenched at a sufficient Brittle fracture through the near-surface chilled region of a ductile iron Original magnification: 1000 Courtesy of Stork Technimet, Inc New Berlin, WI Fig Fracture through the matrix between the graphite flakes of a gray iron Original magnification: 250 Courtesy of Stork Technimet, Inc New Berlin, WI Fig cooling rate and has a microstructure of tempered martensite and some ferrite, the fracture will exhibit features that are a blend of cleavage fracture and ductile tear ridges, often called quasi-cleavage A typical example for lowalloy steel is shown in Fig 10 Fatigue Fatigue fracture in cast components typically exhibits the usual features of a progressive fracture mode, such as relatively flat fracture surface with beach marks and arrest lines, ratchet marks between the origins, striations when examined at high magnification, and an overload fracture at the final fracture region Crack initiation will occur at a site of stress concentration This may be at the surface or at a subsurface anomaly With cast alloys the origin is often found at porosity or nonmetallic inclusions An example of crack initiation at shrinkage porosity in a low-alloy steel casting is shown in Fig 11 As with wrought alloys, a fatigue crack in carbon and low-alloy steels will propagate through the material via microscopic steps and produce fine striations, which cannot be seen with the unaided eye, but can be discerned with a SEM at magnifications above 500 Typical striations in a low-alloy steel suspension component are shown in Fig 12 It is important to understand the difference between these striations and beach marks or arrest lines Beach marks are visually evident on most fatigue fractures in cast components and are shown in Fig 11 The visual, thumbnail, or curved lines that radiate from the origin region are caused by variations in the cyclic stresses and the crack propagation rate These marks are not always indicative of fatigue fracture, but can also be caused by incremental overload steps, although the overload steps are typically less uniform and have a rougher texture Confirmation of a fatigue fracture should be done by examination at high magnification with a SEM It should be noted that fatigue striations are not always discernible on examination at high magnification For example, the appearance of a fatigue fracture through a cast aluminum alloy will appear quite different from cast steel The aluminum alloy will typically have a feathery appearance where the fatigue fracture propagates through the matrix and a rougher, more globular texture where the crack extends around the eutectic silicon particles in the microstructure, as shown in Fig 13 for a laboratory fatigue test specimen Even at higher Fatigue striations in a low-alloy steel casting Original magnification: 2000 Courtesy of Stork Technimet, Inc New Berlin, WI Fig 10 Quasi-cleavage in a heavy-section low-alloy steel casting Original magnification: 1000 Courtesy of Stork Technimet, Inc New Berlin, WI Fig 12 Subsurface fatigue crack initiation in a heavy section low-alloy steel casting Original magnification: 6 Courtesy of Stork Technimet, Inc New Berlin, WI Fig 13 Fig 11 Fatigue fracture through a type 356.0 aluminum alloy in the T6 condition Original magnification: 500 Courtesy of Stork Technimet, Inc New Berlin, WI 244 / Casting Design and Performance magnification, the striations are difficult to discern, as shown in Fig 14 Environmentally Induced Fracture Hydrogen-Assisted Cracking (Intergranular Brittle Fracture) Hydrogen-assisted cracking, also called hydrogen embrittlement, can occur with carbon and low-alloy steels that have been exposed to an environment where hydrogen is generated at the surface of the part This can be from pickling or plating operations or may occur from severe surface corrosion The fracture surface will typically exhibit separation at the grain boundaries and will also exhibit small regions with ductile fracture features called ductile hairlines, have some secondary grainboundary cracking, and show the presence of micropores The features are similar to those found in wrought components, and an example of a heavy-section low-alloy steel with hydrogen-assisted cracking is shown in Fig 15 Rock Candy Fracture (Intergranular Brittle Fracture) Heavy-section carbon and low-alloy steels are susceptible to “rock candy fracture” or concoidal fracture if the steel Fatigue fracture through a type 356.0 aluminum alloy in the T6 condition Original magnification: 5000 Courtesy of Stork Technimet, Inc New Berlin, WI contains excessive amounts of nitrogen and aluminum Aluminum-nitrogen precipitates form at the austenite grain boundaries if the casting is cooled slowly The overload fracture surface exhibits separation at the grain boundaries, and the grains can typically be seen with an unaided eye Examination at high magnification typically reveals fine quasi-cleavage or ductile fracture with linear ruptures where the precipitates are present A typical linear rupture is shown in Fig 16 for a heavy-section low-alloy steel Quench Cracking (Intergranular Brittle Fracture) Quench cracking can occur when a steel casting is quenched from the austenitizing temperature at too fast a rate Intergranular fracture occurs at the prior austenite grain boundaries In most cases the original fracture surface is oxidized during the tempering cycle, as the cracks are usually not detected until after completion of the heat treatment process The fracture surface typically exhibits relatively clean separation between the grains with minimal evidence of ductile fracture or secondary grain-boundary cracking A typical example of a quench crack for a low-alloy steel lever is shown in Fig 17 A coating of temper scale covers the fracture surface A metallographic cross section through the cracked region is usually needed to confirm the presence of intergranular fracture Stress-corrosion cracking (SCC) can occur with cast alloys and is most often encountered with copper-base alloys, such as brass and some bronzes Stress-corrosion cracking occurs when a susceptible alloy is subjected to applied or residual stresses in a corrosive environment This is especially true for some copper alloys when ammonia-based compounds are present The fracture characteristics can be somewhat complex and in some cases difficult to distinguish from corrosion fatigue A typical example of SCC in a bronze alloy C83600 suction roll for the paper industry is shown in Fig 18 The surface exhibits the characteristic jagged features with fine microcracks It should be noted that fracture features are often only discernible at the crack-tip region, or at secondary cracks, as the fracture surface is typically coated with oxidation products caused by the corrosive environment Other alloys, such as ductile iron and steel, can also incur this type of cracking The crack-tip region of a ductile iron head is shown in Fig 19 Fig 14 Fig 16 Linear rupture through a low-alloy steel with rock candy fracture Original magnification: 5000 Courtesy of Stork Technimet, Inc New Berlin, WI Stress-corrosion cracking in a bronze alloy C83600 suction roll shell Original magnification: 1000 Courtesy of Stork Technimet, Inc New Berlin, WI Hydrogen-assisted cracking in a heavy-section low-alloy steel casting Original magnification: 1000 Courtesy of Stork Technimet, Inc New Berlin, WI Quench cracking in a low-alloy steel lever casting Original magnification: 1000 Courtesy of Stork Technimet, Inc New Berlin, WI Stress-corrosion cracking at the tip of a crack in ductile iron Original magnification: 200 Courtesy of Stork Technimet, Inc New Berlin, WI Fig 15 Fig 17 Fig 18 Fig 19 Failure Analysis of Castings / 245 Elevated-temperature rupture in a heatresistant stainless steel Original magnification: 40 Courtesy of Stork Technimet, Inc New Berlin, WI Fig 20 Elevated-Temperature Fracture (Creep) Cast alloys that have been exposed to elevated temperatures for extended periods can incur creep failure if the operating temperature is above the range recommended for the specific alloy The fine features of the fracture surface will typically be totally obliterated from oxidation, and the texture will correspond to the macrostructure of the alloy Creep voids and cracks will develop at the cell boundaries, and the fracture surface can often exhibit a dendritic appearance from the solidification structure of the alloy A typical example of a heatresistant stainless steel fitting is shown in Fig 20 REFERENCES B.A Miller, Overload Failure, Failure Analysis and Prevention, Vol 11, ASM Handbook, ASM International, 2002, p 671–699 R.A Lund, Fatigue Fracture Appearances, Failure Analysis and Prevention, Vol 11, ASM Handbook, ASM International, 2002, p 627–640 W.T Becker, Mechanisms and Appearances of Ductile and Brittle Fracture in Metals, Failure Analysis and Prevention, Vol 11, ASM Handbook, ASM International, 2002, p 587–626 Failures Related to Casting, Failure Analysis and Prevention, Vol 11, ASM Handbook, ASM International, 2002, p 103–155 Casting Design and Performance Pages 247249 Copyright â 2009 ASM Internationalđ All rights reserved www.asminternational.org Inspection of Castings After finishing, castings are inspected for surface quality Inspection can be performed manually by visual checking, manually by template comparison, or by an automated inspection station Visual inspection is simple yet informative A visual inspection would include significant dimensional measurements as well as general appearance Surface discontinuities often indicate the presence of internal discontinuities Computer-assisted coordinate-measuring machines measure both pattern and casting dimensions These machines can perform a variety of dimensional checks ranging from basic geometric measurement to parallel and plane projection The operator simply identifies critical part locations so that the machine can establish a working plane The coordinate-measuring machine can perform in a few minutes the tedious checks that take to h to be done manually For small castings produced in reasonable volume, a destructive metallographic inspection on randomly selected samples is practical and economical This is especially true on a new casting for which foundry practice has not been optimized and a satisfactory repeatability level has not been achieved For castings of some of the harder and stronger alloys, a hardness test is a good means of estimating the level of mechanical properties Hardness tests are of less value for the softer tin bronze alloys because hardness tests not reflect casting soundness and integrity Inspection also includes various methods of nondestructive testing (NDT) to screen castings for imperfections that may be considered to be defects The techniques for NDT of casting are briefly summarized in this chapter The general types of imperfections or defects in castings are listed in Table As a general rule, the method of inspection applied to some of the first castings made from a new pattern should include all those methods that provide a basis for judgment of the acceptability of the casting for the intended application Any deficiencies or defects should be reviewed and the degree of perfection defined This procedure can be repeated on successive production runs until repeatability has been ensured NDT Methods Nondestructive testing (NDT) of cast products is necessary to monitor product quality, depending on the level of quality required Table Casting defects, descriptions, and prevention Casting imperfections or defects Description Prevention Cold shuts Appear as folds in the metal — occurs when two streams of cold molten metal meet and not completely weld Possible causes:  Interruption in the pouring operation  Too slow a pouring rate  Improperly designed gating Pour as quickly as possible Design gating system to fill entire mold quickly without an interruption Preheat the mold Modify part design Avoid excessively long, thin sections Hot tears and cracks Hot tears are cracklike defects that occur during solidification due to overstressing of the solidifying metal as thermal gradients develop Cracks occur during the cooldown of the casting after solidification is complete due to uneven contraction Fill mold as quickly as possible Change gating system; e.g., use several smaller gales in place of one large gate Apply thermal management techniques within the mold (e.g., chills or exothermic material) to control solidification direction and rate Insulate the mold to reduce its cooling rate Modify casting design:  Avoid sharp transitions between thin and thick sections  Taper thin sections to facilitate establishment of appropriate solidification gradients  Strengthen the weak section with additional material, ribs, etc Inclusions Presence of foreign material in the microstructure of the casting Typical sources: Modify gating system to include a strainer core to filter out slag Avoid metal flow turbulence in the gating system that could cause erosion of the mold Improve hardness of the mold and core  Furnace slag  Mold and core material Misruns Incomplete filling of the mold cavity Causes:  Too low a pouring temperature  Too slow a pouring rate  Too low a mold temperature  High backpressure from gases combined with Control mold and metal temperature Increase the pouring rate Increase the pouring pressure Modify gating system to direct metal to thinner and difficult-to-feed sections more quickly low mold permeability  Inadequate gating Porosity Holes in the cast material Causes:  Dissolved or entrained gases in the liquid metal  Gas generation resulting from a reaction Pour metal at lowest possible temperature Design gating system for rapid but uniform filling of the mold, providing an escape path for any gas that is generated Select a mold material with higher gas permeability between molten metal and the mold material Microshrinkage Liquid metal does not fill all the dendrific interstices, causing the appearance of solidification microshrinkage Control direction of solidification:  Design gating system to fill mold cavity so that solidification begins at the extremities and progresses toward the feed gate  Lower the mold temperature and increase the pouring temperature  Add risers, use exothermic toppings to maintain temperature longer  Control cooling rate using chills, insulators, etc in selected portions of the mold 248 / Casting Design and Performance Quality levels dictate the frequency of testing and types of tests being needed The commonly used techniques include:  Liquid penetrant inspection (LPI)  Radiographic inspection  Fluoroscopic inspection and automated      defect recognition Ultrasonic inspection Eddy current inspection Process-Controlled resonant testing Leak test Electrical conductivity measurements Liquid penetrant inspection is extensively used as a visual aid for detecting surface flaws One of the most useful applications, however, is the inspection of alloys susceptible to hot cracking Such cracks are virtually undetectable by unaided visual inspection but are readily detectable by liquid penetrant inspection Liquid penetrant inspection essentially involves a liquid wetting the surface of a workpiece, flowing over that surface to form a continuous and uniform coating, and migrating into cracks or cavities that are open to the surface After a few minutes, the liquid coating is washed off the surface of the casting, and a developer is placed on the surface The developer is stained by the liquid penetrant as it is drawn out of the cracks and cavities Liquid penetrants will highlight surface defects so that detection is more certain The liquid penetrant flows over a surface and enters various types of minute surface openings (0.1 mm (0.4 min.) wide) by capillary action This helps detect surface cracks, laps, laminations, and similar flaws: However, it should be noted that surface condition (cleanliness, roughness) of the part being inspected is critical since false indications can arise from poor surface preparation or condition The three basic penetrant systems commonly used are: shuts, internal shrinkage, porosity, core shifts, and inclusions in aluminum alloy castings Radiography can also be used to measure the thickness of specific sections Aluminum alloy castings are ideally suited to examination by radiography because of their relatively low density; a given thickness of aluminum alloy can be penetrated with approximately one-third the power required for penetrating the same thickness of steel The typical complexity of shape and varying section thicknesses of the castings may require digital radiography or computed tomography Unlike liquid penetrant and eddy current inspection, radiography can satisfactorily detect flaws that are completely internal and located well below the surface of the component If the workpiece is properly oriented during inspection, radiography is capable of detecting defects such as cracks Voids and inclusions having measurable thickness in all directions can be also detected as long as they are not too small in relation to section thickness Radiography is used extensively for evaluation of large components (e.g., steel castings) that exhibit a difference in thickness or physical density The sensitivity, or the ability to detect flaws, of radiographic inspection depends on close control of the inspection technique, including the geometric relationships among the point of x-ray emission, the casting, and the x-ray imaging plane The smallest detectable variation in metal thickness lies between 0.5 and 2.0% of the total section thickness Narrow flaws, such as cracks, must lie in a plane approximately parallel to the emergent x-ray beam to be imaged; this requires multiple exposures for x-ray film techniques and a remote-control parts manipulator for a real-time system Real-time systems have eliminated the need for multiple exposures of the same casting by dynamically inspecting parts on a manipulator, with the capability of changing the x-ray energy for changes in total material thickness These capabilities have significantly improved productivity and have reduced costs, thus enabling higher percentages of castings to be inspected and providing instant feedback after repair procedures Automated Defect Recognition This system has replaced conventional radiography (film x-ray) and consists of an x-ray generator and a detector (an image intensifier or a digital detector) The image created by a detector can be converted to a digital image that may be subsequently processed by a computer program (ADR program) Based on the difference in gray scales of the image, the program can detect defects in the image with great success (see Fig 1) The ADR is used extensively in high-volume detection environments to reduce dependency on a human operator to make decisions Ultrasonic inspection for both thickness and defects is practical with most ferrous castings except for the high-carbon gray iron castings, which have a high damping capacity and absorb much of the input energy The measurement of resonant frequency is a good method of inspecting some ductile iron castings for soundness and graphite shape Electromagnetic testing can be used to distinguish metallurgical differences between castings Aluminum alloy castings are sometimes inspected by ultrasonic methods to evaluate internal soundness or wall thickness The principal uses of ultrasonic inspection for aluminum alloy castings include the detection of porosity in castings and internal cracks in ingots The advantages of ultrasonic tests are as follows:  High sensitivity, which permits the detection of minute cracks  Great penetrating power, which allows the examination of extremely thick sections  Accuracy in measuring of flaw position and estimating defect size  Water-soluble: The penetrants can be removed directly with water  Postemulsifiable: These penetrants have an oil base and, thus, cannot be removed directly with water Consequently, an emulsifier is needed (following application of the penetrant) to make the penetrant soluble in water  Solvent-removable: These also have an oil base and employ a solvent for both precleaning and removal of excess penetrant Each of these systems uses either a visible or a fluorescent penetrant material The visiblepenetrant inspection uses a liquid that is typically red in color and, thus, reveals red indications under visible light On the other hand, the fluorescent penetrant inspection employs penetrants that fluoresce under ultraviolet light Components with complex designs (sharp corners or radii) and/or made with alloys that are prone to hot tearing are often subjected to liquid penetrant inspection Radiographic inspection is a very effective means of detecting such conditions as cold Fig (a) X-ray inspection equipment (b) Digital image of two aluminum castings showing no defects Inspection of Castings / 249 Ultrasonic limitations: tests have the following  Size-contour complexity and unfavorable discontinuity orientation can pose problems in interpreting the echo pattern  Undesirable internal structure—for example, grain size, structure, porosity, inclusion content, or fine dispersed precipitates—can similarly hinder interpretation  Reference standards are required Because castings are rarely simple flat shapes, they are not as easy to inspect as such products as rolled rectangular bars The reflections of a sound beam from the back surface of a parallel-sided casting and a discontinuity are shown schematically in Fig 2(a), together with the relative heights and positions of the reflections of the two surfaces on an oscilloscope screen A decrease in the back reflection at the same time as the appearance of a discontinuity echo is a secondary indication of the presence of a discontinuity However, if the back surface of the casting at a particular location for inspection is not approximately at a right angle to the incident sound beam, the beam will be reflected to remote parts of the casting and not directly returned to the detector In this case, as shown in Fig 2(b), there is no back reflection to monitor as a secondary indication Fig Many castings contain cored holes and changes in section, and echoes from holes and changes in section can interfere with echoes from discontinuities As shown in Fig 2(c), the echo from the cored hole overlaps the echo from the discontinuity on the oscilloscope screen The same effect is shown in Fig 2(d), in which echoes from the discontinuity and the casting fillets at a change in section are shown overlapping on the oscilloscope Magnetic Particle Inspection Magnetic particle inspection is a highly effective and sensitive technique for revealing cracks and similar defects at or just beneath the surface of castings made of ferromagnetic metals The capability of detecting discontinuities just beneath the surface is important because such cleaning methods as shot or abrasive blasting tend to close a surface break that might go undetected in visual or liquid penetrant inspection When a magnetic field is generated in and around a casting made of a ferromagnetic metal and the lines of magnetic flux are intersected by a defect such as a crack, magnetic poles are induced on either side of the defect The resulting local flux disturbance can be detected by its effect on the particles of a ferromagnetic material, which become attracted to the region of the defect as they are dusted on the casting Maximum sensitivity of indication is obtained when a defect is oriented in a direction perpendicular Schematic of the effect of casting shapes on reflection and oscilloscope screen display of sound beams See text for discussion to the applied magnetic field and when the strength of this field is sufficient to saturate the casting being inspected Equipment for magnetic particle inspection uses direct or alternating current to generate the necessary magnetic fields The current can be applied in a variety of ways to control the direction and magnitude of the magnetic field In one method of magnetization, a heavy current is passed directly through the casting placed between two solid contacts The induced magnetic field then runs in the transverse or circumferential direction, producing conditions favorable to the detection of longitudinally oriented defects A coil encircling the casting will induce a magnetic field that runs in the longitudinal direction, producing conditions favorable to the detection of circumferentially (or transversely) oriented defects Alternatively, a longitudinal magnetic field can be conveniently generated by passing current through a flexible cable conductor, which can be coiled around any metal section This method is particularly adaptable to castings of irregular shape Circumferential magnetic fields can be induced in hollow cylindrical castings by using an axially disposed central conductor threaded through the casting Small castings can be magnetic particle inspected directly on bench-type equipment that incorporates both coils and solid contacts Critical regions of larger castings can be inspected by the use of yokes, coils, or contact probes carried on flexible cables connected to the source of current; this setup enables most regions of castings to be inspected Eddy Current Inspection Eddy current inspection consists of observing the interaction between electromagnetic fields and metals In a basic system, currents are induced to flow in the testpiece by a coil of wire that carries an alternating current As the part enters the coil, or as the coil in the form of a probe or yoke is placed on the testpiece, electromagnetic energy produced by the coils is partly absorbed and converted into heat by the effects of resistivity and hysteresis Part of the remaining energy is reflected back to the test coil, its electrical characteristics having been changed in a manner determined by the properties of the testpiece Consequently, the currents flowing through the probe coil are the source of information describing the characteristics of the testpiece These currents can be analyzed and compared with currents flowing through a reference specimen Eddy current methods of inspection are effective with both ferromagnetic and non-ferromagnetic metals Eddy current methods are not as sensitive to small, open defects as liquid penetrant or magnetic particle methods are Because of the skin effect, eddy current inspection is generally restricted to depths less than mm (¼ in.) The results of inspecting ferromagnetic materials can be obscured by changes in the magnetic permeability of the testpiece Changes in temperature must be avoided to prevent erroneous results if electrical conductivity or other properties are being determined © 2009 ASM International All Rights Reserved Casting Design and Performance (#05263G) www.asminternational.org Index A acetic acid (CH3COOH), 164, 165, 167 ACI See Alloy Casting Institute (ACI) acicular transformation structures, 163, 225 Ag alloys, 211(T), 214 Al-Cu cast alloys corrosive (salt) effects, 216, 217(F) discontinuities, 214, 216(F) environmental effects, 214–216(F), 217(F) fatigue crack growth, humidity effects on, 215–216, 217(F) introduction, 211(T), 214 loading conditions, effects of, 216, 217(F) mechanical properties, 214, 215(F), 216(F) microstructure, 214, 215(F), 216(F) temperature effects, 215, 216(F) Alloy Casting Institute (ACI), 175, 176(T), 183(F) aluminum alloy castings, fatigue and fracture properties of Al-Cu cast alloys (see Al-Cu cast alloys) Al-Si-Mg, 210–211(T) component tests, 216–217 composition effects, 214, 215(F) design and manufacture casting discontinuities, effect of, 210 dross, 210 gas porosity, 210 hot isostatic pressing (HIP), 210 introduction, 209 weld repair, 210 weld rework, 209–210 future work, considerations for, 217 introduction, 209 microstructural fineness crack growth rates, 213, 215(F) fatigue crack initiation, effects on, 212–213 fatigue life, 211–212, 213 fracture toughness, 213, 215(F) measurement of, 211, 213(F), 215(F) microstructure, 211, 212(F) premium (high-strength, high-toughness) castings, 211, 212(T) properties, 211, 212(F) residual iron, 214, 215(F) Aluminum Association (AA), 227 aluminum castings, 153(F) junctions, 150–152(F) thin-wall core movement, 126(F) effect of area, 126(F), 127(F) feeding through, 126–127(F) introduction, 125–126(F) strength-to-weight ratio, 126, 127(F) aluminum-silicon alloys, friction and wear of aerospace components, 233 aluminum-silicon wear-resistance materials, 233–234 applications, 231–234(F,T) automotive components, 231–233(T) consumer electronics components, 233 introduction, 227 metallurgy of copper, 228 heating effects, 228–229 introduction, 227–228(F,T) iron, 228 magnesium, 228 manganese, 228–229 properties and structure antimony, 230 cell size, 230–231(F) gas porosity, 230 grain structure, 229, 230(F) heat treatment, 229 introduction, 229(T) microstructural control, 229–230(F) modification, 230(F) refinement, 230 sludge, 230(F) wear behavior abrasive wear, 230 intermetallic constituents, 231(T) matrix hardness, 231 silicon particles, 231 sliding wear, 230 aluminum-silicon wear-resistance materials coatings/surface treatments, 233–234 metal-matrix composites, 233 powder metallurgy, 233 spray casting, 233 anisotropy, 42, 113 apparent surface alteration factors (ASAF), 70 area moment of inertia, 105(F,T), 106(F) equation for, 105(F) ASAF See apparent surface alteration factors (ASAF) austenite, 221–222(F), 223, 224, 225 automated defect recognition (ADR), 248(F) automotive components, 232(T) advanced aluminum bearing alloys, 232, 233(T) bearing alloy components, 232–233(T) cylinder liners, 231–232(T) engine blocks, 231–232(T) pistons, 231, 232(T) B bainite, 163, 225, 241 bainitic transformation structures, 225 bedding sand, 84, 89 Bernoulli’s theorem, 74(F) blackheart, 193, 196(T), 219 blended junctions, 152–153(F) blind holes, 90, 95, 129 blow-holes, 92 bosses, 82–83, 84(F), 89(F), 91, 96(F), 142(F) bottom gating, 77(F), 143 Brinell hardness testing, 240 C CA model See cellular automaton (CA) models CaCO3 See calcium carbonate (CaCO3) CAFE model, 41, 42 calcium carbonate (CaCO3), 168 capability castings, 103, 104 carbon equivalent (CE), 219–220 CARP See computer automated rapid prototyping (CARP) cast carbon steels, corrosion of atmospheric corrosion, 171–173(F,T) high-temperature steam, 172(T), 173(T) introduction, 171 cast housings, 144–146(F) cast iron graphitic, 66 micromodeling, 44 risers and, 11 solidification, during, 10, 11 solidification, lack of shrinkage during, 10 structure and properties, 33 cast irons, basic metallurgy of austenitic structures, 163 bainite, 163 ferrite, 163 introduction, 163(F,T) martensitic structures, 163 pearlite, 163 cast irons, corrosion of alloying, influence of chromium, 164 copper, 164 introduction, 163–164 molybdenum, 164 nickel, 164 silicon, 164(F) titanium, 164 vanadium, 164 calcium carbonate (CaCO3), 168 chromic acid (H2CrO4), 169 coatings conversion, 169 enamel, 169 metallic, 168–169(T) organic, 169 corrosion, forms of, 165–166(T) corrosion services, selection for, 169–170 corrosive environments, resistance to alkali solutions, 167–168 atmospheric corrosion, 168 hydrochloric acid (HCl), 167(F) nitric acid (HNO3), 167(F) organic acids and compounds, 167 other environments, 168, 169(T) phosphoric acid (H3PO4), 167 in saline solution, 168 in soils, 168 sulfuric acid (H2SO4), 166–167(F) in water, 168 crevice corrosion, 165–166 cupric chloride (CuCl2), 168 erosion-corrosion, 166 ferric chloride (FeCl3), 168 flow-induced corrosion, 166 fretting corrosion, 165(T) graphitic corrosion, 165 high-chromium, 165(T) high-nickel austenitic, 165(T), 166 high-silicon, 165(T), 166–167 intergranular attack, 166 introduction, 163 low -and moderately alloyed, 164–165(T) microbiologically induced corrosion (MIC), 166 microstructure, influence of, 164 pitting corrosion, 165–166 stress-corrosion cracking (SCC), 166 © 2009 ASM International All Rights Reserved Casting Design and Performance (#05263G) www.asminternational.org 260 / Index cast irons, corrosion of (continued) unalloyed, 164(T) unalloyed gray, 164 cast irons, fatigue and fracture properties of, 188 constrained thermal test, 188 corrosion fatigue, 188, 191(T) ductile irons, 96(F), 192–193, 194(F,T), 195(F,T), 196(T) fatigue crack growth, 185–186, 190(F,T) fatigue notch sensitivity, 187 fatigue of, 185–188(F,T) finned-disk test, 188 fracture appearance, 186 fracture toughness, 188–189, 192(F), 193(T) gray cast iron, 189–192(F,T), 194(F,T) introduction, 185 load variables, 186–187, 191(F,T) malleable cast irons, 193–194, 196(F,T), 197(F), 198(T) Paris relation, 186 thermal fatigue, 187–188, 191(F) white cast iron, 194, 198(F) cast irons, friction and wear of applications, 225(T) carbon equivalent (CE) value, 219–220 composition value, 219–220 constitution of, 219–221(F,T) cooling rate, 220, 221(T) graphite, 222–224(F,T) gray irons, 219, 221–222 introduction, 219 malleable iron, 219 microstructures acicular, 225 austenite, 225 bainitic, 225 cementite, 225 ferrite, 224 martensite, 225 pearlite, 224 phosphide eutectic, 225 nodular iron, 219 section sensitivity, 220, 221(T) spheroidal iron, 219 tensile properties, 220, 222(F) effect of section on strength, 220–221, 222(F) white irons, 221, 222(F,T) white or chilled iron, 219 CAST program, 210, 211, 216, 217 cast stainless steels, corrosion of composition and microstructure, 175–177(F,T) C-type alloys austenitic alloys, 178–180(F,T) austenitic alloys, intergranular corrosion of, 180–181(F), 182(T) corrosion fatigue, 182 crevice corrosion, 181–182 critical crevice temperature (CCT), 182 duplex alloys, 178–180(F,T), 181 ferritic alloys, 178, 181 fully austenitic alloys, 180, 181(F) martensitic alloys, 178 pitting corrosion, 181–182 pitting resistance number (PREN), 180 stress-corrosion cracking (SCC), 182–183(F) H-type alloys carburization, 177–178(F) introduction, 177 oxidation, 177(F) sulfidation, 177–178(F) introduction, 175, 176(T) cast steels, fatigue and fracture properties of fatigue, influencing factors applied stress effects, 202, 203(F), 204(F,T) cyclic stress-strain behavior, 202–203, 204(F) defects, effect of, 201–202(F) high-cycle axial fatigue behavior, 203–204, 205 (F,T) low-cycle axial fatigue behavior, 203, 205(F,T) section size effects, 201, 202(F) fracture mechanics fatigue crack growth rates (constant amplitude), 207(F,T) introduction, 204–205 J-integral method, 206–207(F,T) plane-strain fracture toughness, 206(F,T) plane-stress fracture toughness, 205–206 threshold crack growth behavior, 207, 208(F,T) variable amplitude fatigue crack initiation and growth, 207 introduction, 199 structure and property correlations, 199–201(F,T) Charpy impact toughness, 199, 200(F) fatigue strength limits, 200–201(T) nil ductility transition temperatures (NDTT), 199–200(F) plane-strain fracture toughness, 200(F) strength and toughness, 199–200(F) tensile strength limits, 200–201(T) casting and solidification processing, modeling of computational thermodynamics, 37–38(F,T) defect prediction (see casting defects) examples high - or low-pressure die casting, 51–53(F), 54(F) investment casting, 53–56(F) fundamentals of basic mathematical formulation, 40 boundary conditions, 40 introduction, 39–40 view-factor radiation model, 40–41 introduction, 37 microstructure simulation cellular automaton (CA) models, 41–42 deterministic method, 41 deterministic micromodeling, 41(F) eutectoid transformation, 44–45(F), 46(F) experimental validations, 45–46, 47(F), 48(T) fading effect, 44 graphite/austenite eutectic transformation, 44 introduction, 41 ledeburite eutectic transformation, 44 micromodeling applications, 44 nucleation model, 41(F), 44 phase-field model, 42–43(F) stochastic method, 41 thermophysical properties density, 39, 40(F) introduction, 38–39 liquid viscosity, 39(F) thermal conductivity, 39(F) casting defects See also casting defects, classification of hot tearing, 49–51(F), 52(F) introduction, 46 macrosegregation, 48–49, 50(F) porosity, 46–48 casting defects, classification of, 251–258(T) casting design and processes casting methods, 9–10, 11(T), 12(T) chills, use of, 32–33 cores, use of, 32–33 defects, 34 (see also casting defects, classification of) expendable-mold casting, 9–10, 11(T), 13–16(F), 17(F) feeding cylinders, solidification of, 30(F), 31 flat plates, solidification of, 29–31(F) introduction, 28–29 fluidity and solidification cooling rates and microstructure, 21–22 defined, 21 introduction, 20–21 liquid-liquid contraction, 21 liquid-solid contraction, 21 solid-solid contraction, 21, 21(F) general principles, 10–13 geometry, 11–13 heat transfer and transport phenomena, 31–33(F) introduction, mold complexity, 18–20(F) permanent mold casting, 16–18(F), 19(F) risers, function of, 22(F) sand mold, components of, 11(F) shape casting, 9–10(F), 12(T) shape casting process, chart of, 10(F) solidification sequence introduction, 22 L-sections, 27–28, 29(F), 30(F) T-sections, 22–26(F) X-sections, 26–27(F) structure and properties discontinuities and defects, 34–36(F) hot isostatic pressing (HIP), 35 inclusions, 35(F) metal penetration, 35–36 overview, 33–34 wedge, casting design and solidification of, 22(F) casting fracture characteristics ductile rupture, 242(F) examination methods, 241 fatigue, 243–244(F) fracture appearance, 241–242(F) introduction, 241 regions of interest, 241 transgranular brittle fracture, 242–243(F) casting molds, dimensional changes in, 115 Casting Technology International, UK (Replicast casting), 16 casting tolerances, factors that control, 104–105 castings, design conversions fabrications deflection, 112 introduction, 111–112 method of sections, using, 112 Mohr’s circle, 112–114 stick-figure sketches, 112 stress correlates to geometry, 112 stress correlation to area, 112 introduction, 110 weldments and assemblies, 110–111 castings, design tips add strength, not mass, 107–108(F) core design principles, 109–110 economical coring, 109–110 functional packaging, 106–107 future parts, 107 gaging parts, 107 service window, 107 thin sections, 109 unequal sections, 108–109 uniform wall thickness, 108 castings, failure analysis of See failure analysis castings, inspection of casting defects, 247(T) (see also casting defects, classification of) introduction, 247(T) NDT methods (see NDT methods) CE See carbon equivalent (CE) cellular automaton (CA) models, 41–42(F), 43 cellular-to-equiaxed transition (CET), 41, 42 cementite, 225 cementite (Fe3C), 34, 163, 164, 222(F), 224, 225 centerline feeding resistance, 66 centerline porosity, 107, 143(F) centroid, 105, 106(F) ceramic filters advantages, 78(F) filter area/choke area ratio, 79–80(F) inclusions, 77–78(T) introduction, 77–78(T) placement, 79(F), 80(F) strainer (choke) cores, 78–79(F) types, 78–79(F) use of, 79–80 CH3COOH See acetic acid (CH3COOH) chaplets, 109 Charpy impact toughness, 192(F), 193–194, 197(F), 199, 200(F), 217 Charpy V-notch data, 192, 199, 200(F) chill zone, 107, 241, 243(F) chilled iron, 219, 225(T) chills FD, extending, 64, 66(F) junctions, 149–150 use of, 32–33 chills, use of, 32–33 chromic acid (H2CrO4), 169 © 2009 ASM International All Rights Reserved Casting Design and Performance (#05263G) www.asminternational.org Index / 261 Chvorinov’s rule, 9, 21, 24–25, 68 close mechanical members, 106 coefficient of thermal expansion (CTE), 227 computer automated rapid prototyping (CARP), 7, 7(F) computer-aided design (CAD), 106, 107 concoidal fracture, 244 conduction (use of term), 40 configuration design, 5, constrained thermal test, 188 cope-and-drag mold, 86 core pins, 96, 98(F) cores cantilever-supported, 90(F) defined, 13 eliminate, designing to, 96–97, 98(F), 99(F) expendable, 92–93(F) metal, 94 molding, principles of, 89 “ram-up” core, 83, 91 ring core, 83, 84(F), 91, 96, 98(F) semicylindrical, 89(F) simplified, 96–97, 99(F) stationary, 94 use of, 32–33 vertical cylindrical, 90–91(F) coring, design for, 98(F) advantages, 89–90(F) core driers, 89 core size limitations, 90–91(F) cores, 89 coring versus drilling, 97, 99(F) designing to eliminate, 96–97, 98(F), 99(F) economical coring, 109–110 gas-related defects, 110 green sand versus dry sand cores, 91(F) investment castings, 94–96(F), 97(T), 98(F) permanent mold castings, cores in, 94(F) principles, general, 89(F), 110 sand cores, designing for the use of, 91–93(F) sand cores, support for, 93–94(F) simplified cores, 96–97, 99(F) thin-wall casting sections, 93(F) tortuous passages, 94 cost drivers, counter gravity casting, 12(T), 18 countergravity filling, 77 crack susceptibility coefficient (CSC), 50–51 critical crevice temperature (CCT), 182(T) cross ribbing, 107, 108(F) CSC See crack susceptibility coefficient (CSC) CuCl2 See cupric chloride (CuCl2) cupric chloride (CuCl2), 168 cylinders, solidification of, 30(F), 31 D DAS See dendrite arm spacing (DAS) defect, (use of term), 237 deflection, 112 dendrite arm spacing (DAS), 211, 212, 213(F) dendrites, 10, 29, 114, 212, 221–222(F), 252(T) design issues and practices casting design process, traditional, 4(F) cost drivers, geometry/material/process interactions dross formation, fluid flow, fluid life, geometry/alloy interactions, 2–3 heat transfer considerations, introduction, pouring temperature, slag formation, solid shrinkage, solidification shrinkage, 1–2 guidelines, 6–7(F) improvement strategies, 4(F) introduction, iterative model, 4(F) process simulation, rigging system design, shape optimization, structured team approach, 4–6(F) die casting abutting cores, 96 casting methods, comparison of, 12(T) design and performance, 96 material thickness, sensitivity to, 107 materials, 18 molding principles, 81 percentage of casting tonnage, 14 diffusivity ratio, 33 directional solidification, directionality, 113 discontinuities and defects See also casting defects, classification of defined, 34 hot isostatic pressing (HIP), 35 inclusions, 35, 35(F) metal penetration, 35–36 porosity, 34–35 distortion alloy, effect of, 160–161(F) differences in solidification times, 155–158(F) in heat treating, 160(F) introduction, 155 mold restraint, due to, 158–159(F) oil canning, 157, 158(F) tie bars, 159–160(F) draft, 86(F), 87, 104 dross, 2, 3, 210 dross formation, 2, ductile irons Charpy impact toughness, 192(F), 195(F) Charpy V-notch data, 192 dynamic fracture toughness, 192(F), 193 dynamic tear energy, 192, 195(F) fatigue strength, 192, 194(F,T), 195(F,T) fracture toughness, 192–193, 196(F,T) lower-shelf fracture toughness, 193, 196(F) micromodeling, 44 mold dilation, 62 riser necks, 71 structure and properties, 34 ductile rupture, 242(F) E ECTFE See ethylene chlorotrifluoroethylene (ECTFE) eddy current inspection, 249 EDS See energy dispersive x-ray spectroscopy (EDS) elevated-temperature facture (creep), 245(F), 257 (T) embrittlement, 177, 179 EMF See exhaust gas recirculation tube (EMF) EMF sources, 106 endurance ratio bending and torsion, 202, 204(F,T) cast carbon and low-alloy steels, 201(T) cast steel, 201, 202(F) defined, 201 ductile irons, 192, 194(F), 195(T) values, 190 wrought steels, 202, 204(F) energy dispersive x-ray spectroscopy (EDS), 239–240 environmentally induced fracture elevated-temperature facture (creep), 245(F) hydrogen-assisted cracking (intergranular brittle fracture), 244(F) quench cracking (intergranular brittle fracture), 244(F) rock candy fracture (intergranular brittle fracture), 244(F) stress-corrosion cracking (SCC), 244(F) EPS See expanded polystyrene (EPS) equiaxed solidification behavior, ETFE See ethylene tetrafluoroethylene (ETFE) ethylene chlorotrifluoroethylene (ECTFE), 169 ethylene tetrafluoroethylene (ETFE), 169 eutectic-type solidification, eutectoid transformation, 44–45(F), 46(F) exhaust gas recirculation tube (EMF), 106 exogenous inclusions, 35 expanded polystyrene (EPS), 15 expendable-mold casting expendable patterns introduction, 15 investment casting, 15(F) lost foam casting process, 15–16(F), 17(F) Replicast casting, 16 mold materials, 14 permanent patterns, 14–15 requirements, 13–14 slurry molding, 14 wax cluster, 15(F) F fabrications, 105, 111–114 fading effect, 44 failure analysis background information, 237 Brinell hardness testing, 240 casting defects, 237 (see also casting defects, classification of) casting fracture characteristics (see casting fracture characteristics) chemical analysis, 239–240 concoidal fracture, 244 data analysis, 241 energy dispersive x-ray spectroscopy (EDS), 239–240 environmentally induced fracture, 244–245 fractography, 238–239 glow discharge spectroscopy (GDS), 239 inductively coupled plasma spectroscopy (ICP), 239 introduction, 237 Knoop microhardness test, 240 macroscopic examination, 238–239 material evaluation, 238–240 mechanical testing, 240 metallography, 240 microscopic examination, 239 micro-void coalescence (MVC), 242 nondestructive evaluation (NDE), 238 optical emission spectroscopy (OES), 239 planning, 237–238 report preparation, 241 Rockwell hardness testing, 240 sample selection, 237–238 scanning electron microscope (SEM), 239 special testing, 240 Vickers microhardness test, 240 visual inspection, 238 x-ray diffraction (XRD), 239 x-ray florescence spectroscopy (XRF), 239 FD See feeding distance (FD) FeCl3 See ferric chloride (FeCl3) feed pad, 23, 23(F), 142, 143 feeding cylinders, solidification of, 30(F), 31 flat plates, solidification of, 29–31(F) introduction, 28–29 reservoirs (feeders or risers), 29 (see also risers) solidification shrinkage and, 102 feeding distance (FD), 64, 65–66(F) FEP See fluorinated ethylene polypropylene (FEP) ferric chloride (FeCl3), 168 ferrite acicular, 225 cast irons, 163, 164 C-type alloys, 178, 179, 180 ductile rupture, 242(F) eutectoid transformation, 44–45(F), 47(F) graphite, 223 gray irons, 222 pearlite, 224 phosphide eutectic, 225 stainless steels, 175–176(F), 177(F) stress-corrosion cracking (SCC), 182(T), 183(T) © 2009 ASM International All Rights Reserved Casting Design and Performance (#05263G) www.asminternational.org 262 / Index finite-element (FE) heat flow solver, 41 finned-disk test, 188 first article castings, 104 5t rule, 140 flake graphite, 222–223(F) flasks, 14, 16(F), 19, 83, 86(F) flat plates, solidification of, 29–31(F) fluid flow, fluid life, 1, 101–102 fluidity Al-Si-Mg cast alloys, 210 aluminum-silicon alloys, 227, 229(T) antimony, 230 carbon steels, 131 cast irons, 163, 185 defined, 21 fluid life, 101–102 low alloy steels, 131 sodium, 230 strontium, 230 thin sections, 109, 121 versus viscosity, 101 fluorinated ethylene polypropylene (FEP), 169 freckles, 48–49, 50f functional packaging, design for close mechanical members, 106 EMF sources, 106 hard points, 106 mating parts, 106 nearby parts, 106 run downs, 106 thermal source, 106 G gaging points, 107 gas porosity, 47–48, 110, 210, 212, 230 gating design bottom gating, 77(F) ceramic filters, 77–80(F,T) countergravity filling, 77 design variables, 73–74 fluid flow, principles of Bernoulli’s theorem, 74(F) law of continuity, 74, 75(F) momentum effects, 74–76(F), 77(F) Reynold’s numbers, 74–75(F) types of flow, 74–76(F), 77(F) ingates, 73(F), 74(F), 75–76(F) pressurized versus unpressurized systems, 76 runner, 73(F), 74(F), 76 runner extensions, 73(F), 74(F), 75, 76 vertical versus horizontal systems, 73(F), 76–77(F) gating system components, 73(F) description, 73 design (see gating design) GD&T See geometric dimensioning and tolerancing (GD&T) GDS See glow discharge spectroscopy (GDS) geometric dimensioning and tolerancing (GD&T), 104 geometry, casting design and area moment of inertia, estimating from sketches, 105 case studies coil rotor for traction motor of railroad wheel assembly, 118–119(F,T) design conversion to a die-cast aluminum fan housing, 116–118(F,T) design conversion to ductile iron casting for a pour chute pivot frame, 115–116(F,T) casting, design conversions to (see castings, design conversions) casting geometry, 103–104 casting tolerances, factors that control, 104–105 castings, specific design tips for (see castings, design tips) drawings and dimensions, 104 fluid life, 101–102 functional packaging, 106–107 introduction, 101 junctions, 104 liquid-to-solid shrinkage of common alloys, guide to, 102(T) metal shrinkage casting molds, dimensional changes in, 115 heat treatment, 114–115 liquid metals, 114 metallurgical solid changes, 114 solid metal contraction, 114 solidification shrinkage, 114 parameters, 101–103 process geometry, 103–104 secondary operations, 104 solidification shrinkage liquid shrinkage, 102 liquid-to solid shrinkage, 102–103(T) patternmaker’s contraction, 103 thermal expansion/contraction, 103 structural properties modulus of elasticity, 103 overview, 103 section modulus, 103 geometry/alloy interactions, 2–3 glow discharge spectroscopy (GDS), 239 graphite flake graphite, 222–223(F) introduction, 222 nodular graphite, 223–224(F,T) quasiflake, 223 graphite/austenite eutectic transformation, 44 graphitic cast irons, 62, 66, 71, 185 gravity casting, 11, 17, 18 gray cast iron fatigue strength, 188–190, 191(T), 194(T) friction and wear of, 221–222 impact strength and toughness, 190–192(F), 194(F) gray irons mold dilation, 62 overview, 219 riser necks, 71 green sand molding, 14, 62, 135 green sand molds, 62, 90, 123 H H2CrO4 See chromic acid (H2CrO4) H2SO4 See sulfuric acid (H2SO4) H3PO4 See phosphoric acid (H3PO4) hard points, 106 HAZ See heat-affected zone (HAZ) HCI See hydrochloric acid (HCl) heat transfer and transport phenomena geometric factors, 32–33 introduction, 31–32 L-sections, 31(F), 32(F), 33 T-sections, 32(F), 33 X-sections, 32(F), 33 heat transfer considerations, heat treating, 105, 124, 160(F), 163 heat-affected zone (HAZ), 178 HF See hydrofluoric acid (HF) high - or low-pressure die casting, 51–53(F), 54(F) high-pressure die casting (HPDC), 10, 12(T), 14, 18 HIP See hot isostatic pressing (HIP) HNO3 See nitric acid (HNO3) hog-out, 110 “hook” shape, molding of, 94, 98(F) hot isostatic pressing (HIP), 35, 210 hot tearing experimental validation, 50–51(F), 52(F) forming of, 35 indicator, 49–50 introduction, 49 hot topping, 69, 70 HPDC See high-pressure die casting (HPDC) hydrochloric acid (HCl), 164, 165, 167(F), 168, 173(T) hydrofluoric acid (HF), 165, 166, 167, 169, 176(T) hydrogen embrittlement, 182, 242, 244 hydrogen-assisted cracking (intergranular brittle fracture), 244(F) I ICP See inductively coupled plasma spectroscopy (ICP) inclusions, 35(F) indigenous inclusions, 35 inductively coupled plasma spectroscopy (ICP), 239 ingates, 73(F), 74(F), 75–76(F), 110 intergranular brittle fracture, 244(F) investment casting, 53–56(F) expendable molds, 15 molding principles, 81 investment castings abutting cores, 96, 98(F) cavities, small, 96, 98(F) coring, design for, 94–95(F), 96(F) feed paths, 144, 145(F) holes in, 95–96, 97(T), 98(F) mold and core, unequal expansion of, 96 mold restraint, distortion due to, 159(F) thin-wall alloy selection, 131–132(F) cooperative designs, 130 defects, prevention of, 130, 131(F) economy, designing for, 130–131, 132(F) feeding ribs, 131, 132(F) introduction, 129(T), 130(F) the mold, chilling effect of, 129, 131(F) mold and metal temperature, 129–130 mold permeability, 130 “RH” Monel, 131, 132(F) tie bars, distortion due to, 159–160(F) uniform sections, 136–138(F) iteratively, J J-integral method, 206–207(F,T) junctions aluminum castings, 150–152(F) blended junctions, 153(F) chills, 149–150 design of, 104 elements, 148–150(F), 151(F) introduction, 147–148(F) L-junctions, 148(F), 149 steel casting junctions, 148–149(F), 150(F) T-junctions, 149 T-junctions versus Y-junctions, 152(F) unequal sections, 152–153(F) X-junctions, 149, 150(F) Y-junctions, 149, 150(F), 151(F) K kaowool, 54, 56 kinematic viscosity, 101 kish, 222, 258(T) Knoop microhardness test, 240 L laminar flow, 75(F), 76 law of continuity, 74, 75(F) ledeburite, 44, 45 ledeburite eutectic transformation, 44 liquid penetrant inspection (PT), 238, 248 liquid shrinkage, 1, as a design consideration, 102 riser design, 61 liquid-liquid contraction, 21 liquid-solid contraction, 21 liquid-to-solid shrinkage, 2, 102–103 See also solidification shrinkage liquidus, 219 lost foam casting process, 14–15, 15–16(F), 17(F) lost wax process See investment casting lost-wax casting See investment casting low pressure casting machine, 18(F) © 2009 ASM International All Rights Reserved Casting Design and Performance (#05263G) www.asminternational.org Index / 263 low pressure casting process (LPPM), 15 low-alloy steels, corrosion of atmospheric corrosion, 171–173(F,T) high-temperature steam, 172(T), 173(T) introduction, 171 LPPM See low pressure casting process (LPPM) L-sections external radius greater than the internal radius, 27–28, 29(F), 30(F) external radius less than the internal radius, 28, 30(F) heat transfer and transport phenomena, 31(F), 32(F), 33 introduction, 27, 29(F) model of, 29(F) M macroporosity, 34 magnetic particle inspection (MT), 238, 249 malleable cast irons blackheart, 193, 196(T), 219 Charpy impact toughness, 193–194, 197(F) dynamic tear energy, 194, 197(F) ferritic, 193, 196(F), 197(F) fracture toughness, 194, 198(T) introduction, 193, 196(F,T), 197(F) whiteheart, 193, 196(T), 219 martensite, 163, 175, 178, 225 mating parts, 106 metal cores, 17, 18, 94, 94(F), 127 metal shrinkage, 114–115 metal yield, 140 metallostatic head, 36 metal-matrix composites (MMC), 12(T), 231, 233 MIC See microbiologically induced corrosion (MIC) microbiologically induced corrosion (MIC), 166 microporosity, 34–35 micro-void coalescence (MVC), 242 modulus of elasticity, 103 Mohr’s circle, 112–113 mold complexity, 18–20(F) molten metal fluidity, 101 mottled iron, 219, 225 MT See magnetic particle inspection (MT) MVC See micro-void coalescence (MVC) N NDT methods automated defect recognition (ADR), 248(F) eddy current inspection, 249 introduction, 247–248 liquid penetrant inspection (PT), 248 magnetic particle inspection (MT), 249 radiographic inspection, 248 ultrasonic inspection (UT), 248–249(F) nearby parts, 106 Nikasil treatment, 233 nil ductility transition temperatures (NDTT), 199–200(F), 242 nitric acid (HNO3), 164, 165, 167(F), 173, 178(F), 179 nodular graphite, 223–224(F,T) nodular graphite iron, 188, 191(T), 219 nondestructive evaluation (NDE) liquid penetrant inspection (PT), 238 magnetic particle inspection (MT), 238 radiographic examination (RT), 238 ultrasonic inspection (UT), 238 nondestructive testing (NDT), 247 NRL See U.S Naval Research Laboratory (NRL) nucleation model, 41(F), 44 O oil canning, 157, 158(F) optical emission spectroscopy (OES), 239 Osprey processing, 233 oxide films, 35, 73, 101, 164, 175, 177 P padding definition of, 23 remote sections, 145, 146(F) unequal sections, 139–144(F), 145(F) uniform sections, 108, 133, 135 parametric design, 5, 6–7 Paris relation, 186 parting lines casting costs, reducing, 19 choice of, 20 crossing, 12 sand molding, 81–82(F), 83(F) stepped, 82, 83(F) pattern maker’s shrink See solid shrinkage patternmaker’s contraction, 103, 104 patternmaker’s shrinkage See solid shrinkage pearlite cast irons, 186, 224(T) cementite, 225 Charpy impact toughness, 192 ductile irons, 193, 195(F), 196(F) dynamic tear energy, 192 eutectoid transformation, 44–45(F), 163 gray irons, 219, 222 malleable cast irons, 193, 219 phosphide eutectic, 225 upper-shelf toughness, 193 white irons, 221, 222(F) perfluoroalkoxy resins (PFA), 169 permanent mold casting, 51–52 cores in, 94(F) feed paths, 143–144(F), 145(F) introduction, 16–17(F) low pressure casting, 18 low pressure casting machine, 18(F) metal cores, 94 methods of, 17–18 molding principles, 81 stationary cores, 94 thin-wall expendable cores, 127 good design, 128–129(F) introduction, 127 large areas, influence of, 128(F) minimum section thickness, 128, 129(F) nonuniform walls, 127–128(F) uniform sections, 136(F) PFA See perfluoroalkoxy resins (PFA) phase-field model, 42–43(F) phosphide eutectic, 219, 225 phosphoric acid (H3PO4), 165, 167, 178, 179(F), 180, 181(F) pitting resistance number (PREN), 180, 182 plane-strain fracture toughness, 206(F,T) plane-stress fracture toughness, 205–206 platelets, 35, 214 polytetrafluoroethylene (PTFE), 169 polyvinyldene fluoride (PVDF), 169 porosity, 34–35 defect prediction, 46–47 experimental validation, 48, 49(F) gas porosity evolution, 47–48 shrinkage porosity, 48 pouring temperature, powder metallurgy (PM), 227, 233 PREN See pitting resistance number (PREN) ProCAST, 54, 55 process geometry, 103–104 production-process verification castings, 104 progressive solidification, PT See liquid penetrant inspection (PT) PTFE See polytetrafluoroethylene (PTFE) PVDF See polyvinyldene fluoride (PVDF) Q quasiflake graphite, 223 quench cracking (intergranular brittle fracture), 244(F) R radiation (use of term), 40 radiographic examination (RT), 238 radiographic inspection, 248 “ram-up” core, 83 rangy components, 111 remote sections, 144, 145(F) reoxidation, 35 Replicast casting, 15, 16 “rework”, 209–210, 217 “RH” Monel, 131, 132(F) ribs in compression, 107 cross ribbing, 107–108(F) unequal sections, 109 webs, 107 rigging system design, 3, 5, ring gate, 55–56 riser design feed metal volume, 62–63 casting geometry, 62–63(T) liquid shrinkage, 62 mold dilation, 62 solidification shrinkage, 62(T) introduction, 61 liquid feed metal availability computerized methods, 68 geometric method, 67–68(F) modulus method, 68, 69(F) shape factor method, 66–67(F) optimum design, 61–66(F,T) requirements, 61–62 riser location directional solidification, 63(F) feeding distance, 65–66 graphitic cast irons, 66 introduction, 63 progressive solidification, 63(F) sections of various thickness, 66, 67(F) solidification mode, 63–64(F) uniform wall thickness, 64–65(F), 66(F) shrinkage-induced casting defects, 61 riser design feeding systems advantages, 68–69, 70(T) breaker cores, 69(F), 71(F) exothermic, 70 exothermic-insulating, 70 insulating, 70 introduction, 68, 69(F) materials, thermal properties of, 69, 70(F) metal contamination, 70 optimum configurations, 71(F) riser necks, 70–71(F) riser size, factors in, 70 risering See riser design risers function of, 10–11 introduction, 10–11 need for, 11 T-sections, 26 rock candy fracture (intergranular brittle fracture), 244(F) Rockwell hardness testing, 240 RT See radiographic examination (RT) run downs, 106 runner extensions, 75, 76 S SAE See Society of Automotive Engineers (SAE) SAE International, 207 salt cores, 14 sample castings, 104, 122 © 2009 ASM International All Rights Reserved Casting Design and Performance (#05263G) www.asminternational.org 264 / Index sand castings mold materials, 14 thin-wall steel, 123–125 alloy selection, 123(F) distortion, 124 examples, 125(F) mold gases, 123 mold-filling, 123 mold-filling problems, 123–124(F) molten metal and mold, friction between, 123 soundness, 125 uniform sections, 134–135(F) sand cores core fragility, 91, 92(F) designing, 91–93(F) support for, 93–94(F) thin core sections, 91–93(F) sand molding basic principles, 81(F), 82(F) bosses, 82–83, 84(F) cope-and-drag mold, 86 coring details, 83–87(F) draft, 86(F), 87 parting lines, 81–82(F), 83(F) radii, location of, 82, 83(F) rib locations, 83, 85(F) undercuts, 83, 84(F) sand molds, 13, 18, 74, 115, 134, 135 sand process, 12(T), 14, 19, 209 “sand-chill composite” mold process See sand process scaling, 32, 255(T) scanning electron microscope (SEM), 239 SCC See stress-corrosion cracking (SCC) Schaeffler diagrams, 175, 176(F) Schoefer diagram, 175, 176, 177(F) second phases, 35 section modulus, 103, 105 SEM See scanning electron microscope (SEM) semipermanent molding, 94 service window, 107 SF See shape factor (SF) SFSA See Steel Founder’s Society of America (SFSA) shape casting, 9–10 chart of shape casting process, 10(F) processes ratings chart, 12(T) shape factor (SF), 67(F) shape optimization, shell, definition of, 53 shell mold castings, 135–136(F) slag, slag formation, slurry molding, 14 Society of Automotive Engineers (SAE), 227 solid shrinkage, 1–2 riser design, 61 solidification shrinkage, 1–2 directional solidification, equiaxed solidification behavior, eutectic-type solidification, liquid shrinkage, 1, liquid-to-solid shrinkage, progressive solidification, riser design, 61 solid shrinkage, 1–2 types of, solid-solid contraction, 21 soluble cores, 95 spheroidal iron, 44, 186(F), 191(F), 195(F), 196(F), 219 spray casting, 233 squeeze casting, 12(T), 15, 233 stainless steel Charpy keyhole impact toughness, 199, 200(F) Charpy V-notch data, 199, 200(F) corrosion fatigue strengths, 191(T) ductile rupture, 242 duplex stainless steel corrosion test results, 180(T) elevated-temperature rupture, 245(F) oil canning, 157, 158(F) petroleum corrosion resistance, 173(T) sand castings, 134(F) stress-corrosion cracks, ferrite pools blocking the propagation of, 183(F) thin sections, 121(F,T), 122, 123(F) thin-wall investment castings, 129(T) tie bars, 159(F) T-junctions versus Y-junctions, 152(F) toughness of solution-annealed duplex stainless steel castings, 177(F) unequal sections, 140, 141(F), 142(F) uniform sections, investment casting, 137(F) Steel Founder’s Society of America (SFSA), 65–66 strainer (choke) cores, 78–79(F) stress-corrosion cracking (SCC), 166, 178, 180, 182–183(F), 244(F) structured team approach, 4–6(F) sulfuric acid (H2SO4), 164, 165, 166–167, 173(T), 179, 180(F) superposition, 105, 112 T TEF See thermoelectric fan (TEF) tempered martensite, 200(F), 224(T), 243 tensile strength (TS), 186(F), 188 thermal source, 106 thermoelectric fan (TEF), 116–117 thin sections designing, 109 introduction, 121(F,T) stainless steel, 121(T), 122 thinnest wall, determination of, 121–122(F) thin-wall aluminum castings, 125–127(F) thin-wall investment castings, 129–132(F,T) thin-wall magnesium castings, 125–127(F) thin-wall permanent mold castings, 127–129(F) thin-wall steel sand castings, 123–125(F) tie bars distortion, 159–160(F) use of, 21 total cost (use of term), Tresca’s hexagon, 113 truss-type castings, 126, 127(F) T-sections heat transfer and transport phenomena, 32(F), 33 solidification sequence factors influencing, 22–24(F) introduction, 22, 23(F) riser placement, 32(F) sequence graphs, 24–26 U ultrasonic inspection (UT), 238, 248–249(F) undercuts, 83, 84(F) unequal sections 5t rule, 140 housings, 144–146(F) introduction, 139(F) junctions, 152–153(F) padding or other feed paths, 139–144(F), 145(F) investment castings, 144, 145(F) permanent mold casting, 143–144(F), 145(F) remote section, designs that reduce the mass of, 144, 145(F) uniform sections introduction, 133–134(F) investment castings, 136–138(F) permanent mold castings, 136(F) sand castings, 134–135(F) shell mold castings, 135–136(F) U.S Naval Research Laboratory (NRL), 66–67(F) UT See ultrasonic inspection (UT) V vacuum die casting, 12(T), 14, 15 vacuum riserless/pressure riserless casting (VRC/PRC), 15, 18 vermicular graphite iron, 185, 190(T), 195(F) Vickers microhardness test, 240 view-factor radiation model, 40–41 viscosity, 101 voids, 2, 108, 133, 147, 210, 248 VRC/PRC See vacuum riserless/pressure riserless casting (VRC/PRC) W weld joints, 113 weld repair, 210 weld rework, 209–210 welds, 112, 113–114, 203(F) white cast iron fatigue and fracture properties, 194, 198(F) friction and wear of, 221, 222(F,T) overview, 219 structure and properties, 33–34 whiteheart, 193, 196(T), 219 wrist-pin bosses, 143–144(F) X x-ray diffraction (XRD), 239 x-ray florescence spectroscopy (XRF), 239 XRD See x-ray diffraction (XRD) XRF See x-ray florescence spectroscopy (XRF) X-sections equal opposite legs, 26–27(F) heat transfer and transport phenomena, 32(F), 33 three legs equal, 27(F), 28(F) ASM International is the society for materials engineers and scientists, a worldwide network dedicated to advancing industry, technology, and applications of metals and materials ASM International, Materials Park, Ohio, USA www.asminternational.org This publication is copyright â ASM Internationalđ All rights reserved Publication title Product code Casting Design and Performance 05263G To order products from ASM International: Online Visit www.asminternational.org/bookstore Telephone 1-800-336-5152 (US) or 1-440-338-5151 (Outside US) Fax 1-440-338-4634 Mail Customer Service, ASM International 9639 Kinsman Rd, Materials Park, 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