Astm stp 1085 1990

STP 1085 Quantitative Methods in Fractography Bernard M Strauss and Susil K Putatunda, editors ASTM 1916 Race Street Philadelphia, PA 19103 Copyright by ASTM Int'l (all rights reserved); Thu Dec 31 13:55:23 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Library of Congress Cataloging-in-Publication Data Quantitative methods in fractography/Bernard M Strauss and Susil K Putatunda, editors (STP 1085) Papers presented at a symposium held 10 Nov 1988 in Atlanta, Ga., sponsored by ASTM Committees E-9 on Fatigue and E-24 on Fracture Testing Includes bibliographical references "ASTM publication code number (PCN) 04-010850-30" T.p verso ISBN 0-8031-1387-0 Fractography Congresses I Strauss, Bernard M., 1946II Putatunda, Susil K., 1948III ASTM Committee E-9 on Fatigue IV ASTM Committee E-24 on Fracture Testing TA409.Q36 1990 620.1' 126 dc20 Copyright by A M E R I C A N 90-35242 CIP S O C I E T Y F O R T E S T I N G AND M A T E R I A L S 9 All rights reserved No part of this publication 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 prior written permission of the publisher NOTE The Society is not responsible, as a body, for the statements and opinions advanced in this publication Peer Review Policy Each paper published in this volume was evaluated by three peer reviewers The authors addressed all of the reviewers' comments to the satisfaction of both'the technical editor(s) and the ASTM Committee on Publications The quality of the papers in this publication reflects not only the obvious efforts of the authors and the technical editor(s), but also the work of these peer reviewers The ASTM Committee on Publications acknowledges with appreciation their dedication and contribution of time and effort on behalf of ASTM Printed in Battimore MD June 1990 Copyright by ASTM Int'l (all rights reserved); Thu Dec 31 13:55:23 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Foreword This publication, Quantitative Methods in Fractography, contains papers presented at the symposium on Evaluation and Techniques in Fractography, which was held 10 Nov 1988 in Atlanta, Georgia Two ASTM committees, Committees E-9 on Fatigue and E-24 on Fracture Testing, sponsored the event The symposium cochairmen were Bernard M Strauss Teledyne Engineering Services, and Susil K Putatunda, Wayne State University, both of whom also served as editors of this publication Copyright by ASTM Int'l (all rights reserved); Thu Dec 31 13:55:23 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Contents Overview Applications of Quantitative Fractography and Computed Tomography to Fracture Processes in M a t e r i a l s - - S T E P H E N D A N T O L O V I C H , A R U N M G O K H A L E , AND C L A U D E B A T H I A S Relationships Between Fractographic Features and Material Toughness-D P HARVESt' lI AND M I JOLLES 26 Quantitative Analysis of Fracture Surfaces Using Fractals D J ALEXANDER 39 Analysis and Interpretation of Aircraft Component Defects Using Quantitative Fractography N T G O L D S M I T H AND G C L A R K 52 Characteristics of Hydrogen-Assisted Cracking Measured by the Holding-Load and Fractographic MeIhod NAOTAKE OHTSUKAAND H I R O S H I Y A M A M O T O 69 Fractographic Study of Isolated Cleavage Regions in Nuclear Pressure Vessel Steels and Their Weld Metals x J ZHANG, A KUMAR, R W ARMSTRONG,AND G R IRWIN 89 Fractographic and Metallographic Study of the Initiation of Brittle Fracture in Weldments P L HARRISON,D J ABSON, A R JONES, AND D J SPARKES 102 Cracking Mechanisms for Mean Stress/Strain Low-Cycle Multiaxial Fatigue Loadings PETER K U R A T H AND ALl F A T E M I 123 Corrosion Fatigue Crack Arrest in Aluminum Alloys R J H WANHILL AND L SCHRA 144 Author Index 167 Subject Index 169 Copyright by ASTM Int'l (all rights reserved); Thu Dec 31 13:55:23 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized STP1085-EB/Jun 1990 Overview The past two decades have seen the development of fractography of materials from a research tool to an important everyday component of failure analysis and materials characterization The vast body of work in this area has led to volumes of photographs describing fractographic features in general qualitative terms It also has presented researchers with a foundation of evidence that quantitative assignment of selected parameters can relate specific fractographic features to material properties On 10 Nov 1988, a one-day symposium, sponsored by ASTM Committees E-9 on Fatigue and E-24 on Fracture Testing, was held in Atlanta, Georgia, covering the latest developments and discoveries in both methodology and interpretation of quantitative fractographic methods It sought to provide a benchmark of progress in this science as we enter the 1990s In this publication, which is based upon that symposium, an overview of recent developments in quantitative fractography and computed tomography in composites is presented by Antolovich, Gokhale, and Bathias, while Harvey and Jolles relate fractographic features in HY-100 steel and 2024 aluminum to the critical strain energy density Alexander has attempted to relate fracture surfaces to mechanical properties by means of fractals and has found that, while fracture surface profiles are fractal, there does not seem to be a clear correlation between the fractal dimension and the mechanical properties or the microstructures Goldsmith and Clark present a discussion of the successful analysis of aircraft components by means of quantitative techniques that have been employed at the Aeronautical Research Laboratory in Melbourne, Australia, for the past 15 years Quantitative analysis of specific fracture processes is then discussed in the remaining five papers, which are the following: Ohtsuka and Yamamoto on hydrogen-assisted cracking; Zhang, Kumar, Armstrong, and Irwin on cleavage; Harrison, Abson, Jones, and Sparkes on brittle fracture in steel weldments; Kurath and Fatemi on low-cycle fatigue in steel and Inconel 718; and Wanhill and Schra on corrosion fatigue crack arrest in aluminum alloys These works demonstrate the value of applying quantitative methods to fractographic features and utilizing this information in predicting material behavior The examples presented here by these authors further the understanding of fracture processes in polycrystaline materials and provide a sound basis for further studies Bernard M Strauss Teledyne Engineering Services, Waltham, MA 02254-9195; symposium cochairman and editor Susil K Putatunda Wayne State University, Detroit, MI 48202; symposium cochairman and editor Copyright by ASTM Int'l (all rights reserved); Thu Dec 31 13:55:231 EST 2015 Downloaded/printed Copyright*1990byby ASTM International www.astm.org University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized Stephen D Antolovich, Arun M Gokhale, and Claude Bathias Applications of Quantitative Fractography and Computed Tomography to Fracture Processes in Materials REFERENCE: Antolovich, S D., Gokhale, A M., and Bathias, C., "Applications of Quantitative Fractography and Computed Tomography to Fracture Processes in Materials," Quantitative Methods in Fractography, A S T M STP 1085, B M Strauss and S K Putatunda, Eds., American Society for Testing and Materials, Philadelphia, 1990, pp 3-25 ABSTRACT: An overview of recent developments in quantitative fractography (QF) and computed tomography (CT) is presented with emphasis on applications of these tools to failure analysis and the identification of fundamental fracture processes QF yields information concerning the geometric attributes of the microstructural features on the fracture surface and quantitative descriptors of the fracture surface geometry By way of example, this methodology is applied to the case of a composite fabricated [rom an AI/Li matrix and alumina (A1203) fibers to delineate those defects which play the most important role in the fracture process The internal damage state of a material can be studied by CT; such information is not accessible through conventional fractographic approaches CT results for damage detection are given for graphite/epoxy and metal-matrix composites New applications of CT to address important unanswered questions in the fracture field are suggested Integration of QF, stereology, and CT has the potential to evolve into a very powerful method for the study of failure processes in all classes of materials KEY WORDS: quantitative fractography, stereology, computed tomography, fracture, crack propagation, fractography The end point of deformation and fracture processes is the generation of fracture surface The geometry of the fracture surface and the associated microstructural features contain information concerning the processes that lead to fracture, in a subtle and complex manner The necessary first step for unraveling this puzzle is quantitative characterization of the fracture surface geometry; this is the basic aim of quantitative fractography There have been significant advances in the theoretical and experimental aspects of quantitative fractography during the past decade It is the purpose of this paper to present an overview of these developments and to point out practical applications of the results The field of stereology will be reviewed as it relates to quantitative fractography, and the developing science of computed tomography, in which the internal defect state can be analyzed, will also be discussed and related to practical problems of current interest Director and professor, and associate professor of materials engineering, respectively, Mechanical Properties Research Laboratory, School of Materials Engineering, Georgia Tech, Atlanta, GA 303320245 Professor of materials science, Conservatoire Nationale des Arts et Metiers 75141 Paris, France EST 2015 Copyright by ASTM Int'l (all rights reserved); Thu Dec 31 13:55:23 Downloaded/printed by Copyright9 1990 by ASTM lntcrnational www.astm.org University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized QUANTITATIVEMETHODS IN FRACTOGRAPHY Quantitative Fractography Definition and Applications Quantitative fractography is concerned with the geometrical characteristics of microstructural features on the fracture surface such as numbers per unit area, sizes, area fractions, and so forth It is also concerned with the geometrical characterization of the fracture surface through parameters such as surface roughness, fracture surface anisotropy, fractal characteristics etc It has been successfully applied to failure analysis, to studies of creep cavitation, to correlations of surface roughness with mechanical behavior, etc., and it may be used (although to the best knowledge of the authors this has never been done) to obtain accurate measures of the surface energies of fracture in brittle systems When successful, quantitative fractography should lead to a better understanding of fundamental processes that occur in materials and, thus, to improved materials and to more appropriate applications of existing materials Experimental Techniques A variety of different experimental techniques have been developed in the past to study fracture surfaces The details of these techniques, their advantages, and limitations are discussed in some detail by Underwood [1], Exner and Fripan [2], Wright and Karlsson [3], Coster and Chermant [4], and Underwood and Banerji [5,6] In a broad sense, the basic approaches can be classified as follows: (a) methods based on stereoscopic images of the fracture surface and (b) techniques involving metallographic sectioning of the fracture surface, i.e., profilometric methods Stereoscopy provides nondestructive techniques for the study of fracture surfaces The Cartesian coordinates of different points on the fracture surface are determined by using stereo scanning electron microscope (SEM) pairs, i.e., two micrographs of the same field taken at small differences in tilt angle The resulting parallax is directly proportional to the elevation differences between the two points in the image This yields a procedure for determining the z coordinate of any given point (x,y) on the SEM image The (x,y,z) coordinates of different points of SEM fractograph can be thus determined The data can be utilized to generate "carpet" plots of the fracture surface via computer graphics: the fracture surface roughness and orientation distribution can be calculated [2] from this information The input can also be utilized to generate fracture profiles [7,8] The stereoscopic techniques can be automated to reduce the measurement time and effort [9,10] Profilometry is the study of sections through the fracture surface Depending on the sectioning geometry, it is possible to obtain vertical [11], horizohtal [12], or slanted [13] sections The vertical sections can be generated by using standard metallographic techniques, and they simultaneously reveal the microstructure below the fracture surface Furthermore, the measurements on such fracture profiles often simplify the subsequent stereological analysis The quantitative descriptors of fracture surface geometry require a reference direction for their definition, interpretation, and estimation The natural choice for the reference axis is the direction normal to an average plane through the fracture surface The vertical sections contain this reference axis, called the "'vertical" axis Figure la shows a schematic fracture surface and Figure lb shows a vertical section and corresponding fracture profile The fracture profile can be quantified via digital image analysis The (x,y) coordinates of the Copyright by ASTM Int'l (all rights reserved); Thu Dec 31 13:55:23 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorize ANTOLOVICH ET AL ON COMPUTED TOMOGRAPHY t.Z Y (a) (b) FIG (a) Schematic fracture surface and relative orientation of the vertical sectioning plane; (b) schematic vertical section fracture profile (Z = vertical axis) points on fracture profile are obtained at preselected length increments (called digitizing ruler length) by tracing the profile image over the digitizing tablet with the help of a cursor [14]; the coupled microprocessor is used to store and process the data The resolution is a function of the ruler length The profile roughness parameter RL is defined as follows [11] RL = -hp (1) where, h0 is the total profile length, and hp is its projected length on a line perpendicular to the vertical axis; overlaps in the projected length are not counted RL can have any value ranging from one to infinity The orientation of a line element on the fracture profile is specified by the angle between the normal to the line element and the vertical axis, 0- The concept of orientation is illustrated in Fig The orientation distribution function of the line elements on the fracture profile (PODF) gives the fraction of profile length in the orientation range to (0 + dO); hence, it is a measure of the fracture profile anisotropy RL and PODF can be calculated from digitized profile data Recently, the horizontal profile roughness parameter RLH has been defined where the overlaps in the projected length are Z Z dL(~r d kOg) [ w FIG Specification of orientation of line elements on fracture profile (Z = vertical axis) Copyright by ASTM Int'l (all rights reserved); Thu Dec 31 13:55:23 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized QUANTITATIVEMETHODS IN FRACTOGRAPHY accounted for [15] RL~ and RL yield the fraction of true profile length [16] having overlaps, ~0 [RL RLn] Rz ~176 = (2) Quantitative Descriptors of Fracture Surface Geometry The fracture surface roughness parameter, Rs, is equal to the ratio of the true area of fracture surface and its projected area on the plane perpendicular to the vertical axis [13,1 7]; the overlaps in the projected area are not counted The orientation of a surface element on the fracture surface is specified by angles + and referenced to its normal vector ~r (See Fig 3) The fracture surface orientation distribution function (SODF) represents the fraction of fracture surface area having orientation in any given solid angle range 12 to (~ + dO) (where, df~ - sin + dO d+); hence, it is a measure of the fracture surface anisotropy The SODF can be calculated from the profile data, provided certain assumptions are made concerning its functional form Analogous to RL", one can define Rs H where the overlaps in the projected area are accounted for [15] Rs n is determined by SODE The fraction of overlapped fracture surface area 130 can be determined as follows [16] 130 - Rs - Rs n Rs (3) A significant simplification in the measurements and the analysis is possible when the SODF is symmetric with respect to the vertical axis In such a case, all the vertical section fracture profiles are statistically equivalent; hence, a single vertical section profile contains the necessary information for estimation of Rs, SODF, Rs n, and [30.The symmetry assumption has been experimentally verified [18,19] in a number of systems; it is expected to be a good approximation for fracture surfaces of materials having isotropic microstructure For fracture surfaces having a symmetric SODF, Underwood and Banerji [19] and Gokhale and Underwood [20] have developed the following equations to estimate Rs from RL Rs = 4(RL 1) + (4) 7r Z Z ~ dS(O, Y Y FIG Specification of orientation of surface elements on fracture surface (Z = vertical axis) Copyright by ASTM Int'l (all rights reserved); Thu Dec 31 13:55:23 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized WANHILL AND SCHRA ON CORROSION FATIGUE CRACK ARREST 155 b,o I L5 Copyright by ASTM Int'l (all rights reserved); Thu Dec 31 13:55:23 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized 156 QUANTITATIVEMETHODS IN FRACTOGRAPHY if ? ^ ,,-n "8 "8 = I '~ ~ ~ ~ "" ,;4 ~ u Copyright by ASTM Int'l (all rights reserved); Thu Dec 31 13:55:23 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized WANHILL AND SCHRA ON CORROSION FATIGUE CRACK ARREST 157 Discussion Corrosion Fatigue Crack Arrest The present work provides additional evidence for corrosion fatigue crack arrest in aluminum alloys Sump tank water was more effective in causing crack arrest than synthetic seawater Fatigue fracture characteristics in the near-threshold regime were similar for all three environments (laboratory air, sump tank water, and synthetic seawater) The only clear difference was the presence of corrosion product layers on the fracture surfaces of specimens fatigued in sump tank water and synthetic seawater At crack arrest the thicknesses of the corrosion product layers were probably sufficient to block the crack tip The trends observed for crack closure, Fig 2, agree with this contention From these observations we conclude that crack blocking by corrosion product layers is primarily responsible for corrosion fatigue crack arrest, as suggested previously [1,2] Other possible mechanisms, notably crack-tip blunting and branching and enhanced roughnessinduced crack closure, not appear to play a role, since the fracture topographies were similar at similar positions on the fatigue crack growth curves Corrosion Fatigue Mechanisms There appears to be a consensus that the acceleration of fatigue crack growth by corrosion is primarily the result of embrittlement by hydrogen produced by reactions of the environment with newly created metal surfaces at the crack tip [3,4,16,17] The present work provides additional evidence for this, notably for 7475-T761 in the near-threshold regime Active path corrosion occurs concomitantly with hydrogen production at the crack tip In the near-threshold regime the resulting corrosion products can cause crack blocking leading to fatigue crack growth retardation and arrest There are thus two mutually competitive processes which have opposite effects on nearthreshold fatigue crack growth rates [3,4] This explains why the crack growth curves for fatigue in sump tank water and synthetic seawater cross the crack growth curves for fatigue in air (Fig 1) In other words, crack blocking has a dominant effect on fatigue crack growth rates only at the lowest stress intensity levels Enhancing Corrosion Fatigue Crack Arrest As stated at the beginning of this paper, it might be possible to enhance fatigue crack growth retardation and arrest by adding inhibitors to the environment and to metal surface treatments However, the situation is complicated by the two competing processes, hydrogen embrittlement and crack blocking, which nevertheless depend on each other For example, if active path corrosion and the formation of corrosion products increase, there is a concomitant increase in hydrogen production What is required is a mixture of inhibitors that promote the buildup of stable corrosion product layers within the fatigue crack and at the same time prevent hydrogen entry into the metal This requirement is exactly the purpose of multifunctional inhibitors that have been used successfully for crack growth retardation and arrest in high-strength steels [5,6] Thus, it may be concluded that the prospects for enhancing corrosion fatigue crack arrest in aluminum alloys are reasonable Apart from the exact choice of inhibitors, which is more or less a trial-and-error process, the main problem is to add them in an effective manner to the environment and to metal surface treatments This is the task which researchers at the U.S Naval Air Development Center (NADC) have set themselves Copyright by ASTM Int'l (all rights reserved); Thu Dec 31 13:55:23 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authoriz 158 QUANTITATIVE METHODS IN FRACTOGRAPHY Copyright by ASTM Int'l (all rights reserved); Thu Dec 31 13:55:23 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized WANHILL AND SCHRA ON CORROSION FATIGUE CRACK ARREST 159 ~tq Copyright by ASTM Int'l (all rights reserved); Thu Dec 31 13:55:23 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized 160 QUANTITATIVE METHODS IN FRACTOGRAPHY FIG Example of cleavage-like facets in the overload region for 7475-T761 fatigued in sump water crack growth direction left to right Copyright by ASTM Int'l (all rights reserved); Thu Dec 31 13:55:23 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized WANHILL AND SCHRA ON CORROSION FATIGUE CRACK ARREST 161 TABLE Maximum crack-tip opening displacements at fatigue crack arrest Materials Environments AK 61: 2.82 0.20 sump tank water 3.59 0.32 syuthetlc seawater 2.99 0.22 laboratory 0.I Crack a r r e s t air 2024-T3 Alclad 0.5 0.1 laboratory air 1,96 0.31 sump tank water 2.48 0.50 laboratory air 1.74 0.06 sump t a n k water 3.06 0.19 synthetic 2.16 0.09 laboratory air 1.42 O 13 sump t a n k w a t e r 2.07 0.28 seawater 7475-T761 0.5 Conclusions Investigation of the constant amplitude low stress-intensity fatigue crack growth behavior of 2024-T3 and 7475-T761 aluminum alloys in laboratory air, sump tank water, and synthetic seawater has shown that Corrosion fatigue crack growth retardation and arrest occurs in both sump tank water and synthetic seawater, resulting in crack arrest at higher AK values than in air Sump tank water is more effective in causing crack arrest Crack blocking by corrosion product layers is primarily responsible for corrosion fatigue crack arrest As previously suggested [3,4], there are two mutually competitive processes, hydrogen embrittlement and crack blocking, that have opposite effects on nearthreshold fatigue crack growth rates Crack blocking has a dominant effect only at the lowest stress-intensity levels This explains why the crack growth curves for fatigue in sump tank water and synthetic seawater are initially below the crack growth curve for fatigue in air but subsequently rise above it The prospects for enhancing corrosion fatigue crack arrest in high-strength aluminum alloys, and hence the durability of aircraft structures, appear to be good Use can be made of multifunctional inhibitors that promote the buildup of stable corrosion product layers within the fatigue crack and at the same time prevent hydrogen entry into the metal The main problem is a practical one: how to add the inhibitors to the environment and to metal surface treatments in an effective manner Acknowledgments This investigation was done under contract to the Netherlands Agency for Aerospace Programs (NIVR) The assistance of A M Otter, H J Kolkman, and P R Hessels is much appreciated Copyright by ASTM Int'l (all rights reserved); Thu Dec 31 13:55:23 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions aut 162 QUANTITATIVEMETHODS IN FRACTOGRAPHY Copyright by ASTM Int'l (all rights reserved); Thu Dec 31 13:55:23 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized WANHILL AND SCHRA ON CORROSION FATIGUE CRACK ARREST 163 I F~ Copyright by ASTM Int'l (all rights reserved); Thu Dec 31 13:55:23 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized 164 QUANTITATIVE METHODS IN FRACTOGRAPHY ~ ,~ o o N A ! ,.# Copyright by ASTM Int'l (all rights reserved); Thu Dec 31 13:55:23 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized WANHILL AND SCHRA ON CORROSION FATIGUE CRACK ARREST 165 References [1] Brownhill, D J., Davies, R E., Nordmark, G E., and Ponchel, B M., "Exploratory Developments for Design Data on Structural Aluminum Alloys in Representative Aircraft Environments," Final Report AFML-TR-77-102, Air Force Materials Laboratory, Dayton, OH, July 1977 [2] Nordmark, G E and Fricke, W G., Journal of Testing and Evaluation, Vol 6, 1978, pp 301303 [3] Vasudevan, A K and Suresh, S., Metallurgical Transactions A, Vol 13A, 1982, pp 2271-2280 [4] Suresh, S., Vasudevan, A K., and Bretz, P E., Metallurgical Transactions A, Vol 15A, 1984, pp 369-379 [5] Lynch, C T., Bhansali, K J., and Parrish P A., "'Inhibition of Crack Propagation of High Strength Steels Through Single and Multifunctional Inhibitors,'" Final Report AFML-TR-76-120, Air Force Materials Laboratory, Dayton, OH, August 1976 [6] Agarwala, V S and De Luccia, J J., Corrosion NACE, Vol 36, 1980, pp 208-212 [7] Miller, R N., Fatigue Prevention and Design, Engineering Materials Advisory Services Ltd., Warley, West Midlands (U.K.), 1986, pp 353-362 [8] Stoltz, R E and Pelloux, R M., Corrosion NACE, Vol 29, 1973, pp 13-17 [9] Wanhill, R J H., Engineering Fracture Mechanics, Vol 30, 1988, pp 233-260 [10] Bucci, R J., "Development of a Proposed Standard Practice for Near-Threshold Fatigue Crack Growth Rate Measurement," Report No 57-7%14, Alcoa Laboratories, Alcoa Center, PA, December 1979 [11] Wanhill, R J H and Schra, L., "Corrosion Fatigue Crack Arrest in Aluminum Alloys: Basic Data," Technical Report 87128 L, National Aerospace Laboratory, Amsterdam, The Netherlands, July 1987 [12] Stofanak, R J., Hertzberg, R W., Leupp, J and Jaccard, R., Engineering Fracture Mechanics, Vol 17, 1983, pp 541-554 [13] Yoder, G R., Cooley, L A., and Crooker, T W., "On Microstructural Control of Near-Threshold Fatigue Crack Growth in 7000-Series Aluminum Alloys," Memorandum Report 4787, Naval Research Laboratory, Washington, DC, April 1982 [14] Underwood, E E and Banerji, K Materials Science and Engineering, Vol 80, 1986, pp 1-14 [15] Albrecht, J., Bernstein, I M., and Thompson, A W., Metallurgical Transactions A, Vol 13A, 1982, pp 811-820 [16] Wei, R P., buernational Conference on Fatigueof Engineering Materials and Structures, Mechanical Engineering Publications Ltd., London, 1986, Vol II, pp 339-346 [17] Wei, R P., Pao, P S., Hart, R G., Weir, T W., and Simmons, G W., Metallurgical Transactions A, Vol I1A, 1980, pp 151-158 Copyright by ASTM Int'l (all rights reserved); Thu Dec 31 13:55:23 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized STP1085-EB/Jun 1990 Author Index A Abson, D J., 102 Alexander, D J., 39 Antolovich, S D., Armstrong, R W., 89 B Bathias, C., 12 Clark, G., 52 F Fatemi, A., 123 J Jolles, M I., 26 Jones, A R., 102 K Kumar, A., 89 Kurath, P., 123 O Ohtsuka, N., 69 S Schra, L., 144 Sparkes, D J., 102 G Gokhale, A M., Goldsmith, N T., 52 N Harrison, R L., 102 Harvey, D P II, 26 I Irwin, G R., 89 W Wanhill, R J H., 144 Y Yamamoto, H., 69 Z Zhang, X J., 89 Copyright by ASTM Int'l (all rights reserved); Thu Dec 31 13:55:23167 EST 2015 Downloaded/printed byby ASTM International Copyright*1990 www.astm.org University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized STP1085-EB/Jun 1990 Subject Index A Aircraft component defects, using quantitative fractography, 52, 61 Airframes, 144 Aluminum alloys, 52, 144 Aluminum, 2024, composition, 27 (table) ASTM test method E 813-86: 74, 76 B Brittle fracture in weldments, 102 Brittle systems, C Chemical composition of pressure vessel steels, 90 (table) Cleavage fracture in nuclear pressure vessel steels, 89 in weldments, 102 Computed tomography, Corrosion fatigue, 144 Crack formation and growth, 123 Crack growth aircraft components, 53-54, 58 hydrogen-assisted cracking, 69 in aluminum alloys, 146-153 mean stress/strain, 123 Cracking, hydrogen-assisted, 69 Crack orientation, 123, 144 Crack propagation, Crack tip blocking, 144 Critical strain energy density, 26 D Damage detection, Damage, shear type, 123 Defects, 52 Deformation, Diffusion of hydrogen Durability of aluminum alloys, 144 E Experimental techniques, fractography, F Failure analysis, 3, 26, 52-54 Fatigue crack propagation, 52, 144 multiaxial, 123 striations, 52 thresholds, 144 Fractals, 39 Fractography analysis of aircraft defects, 52 application to materials processes, brittle fracture in weldments, 102 corrosion fatigue, 144 hydrogen-assisted cracking, 69 nuclear pressure vessel steels, 89 quantitative analysis using fractals, 39 relationship to material toughness, 26 weld metals, 89 Fracture analysis, 52 mechanics, 52, 102, 144 surfaces, 3-5, 39 toughness, 69, 89 transition, 89 ILl Heat-affected zone, 102 Holding load and fractographic (HLF) test method, 72-74 169 Copyright by ASTM Int'l (all rights reserved); Thu Dec 31 13:55:23 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized 170 QUANTITATIVE METHODS IN FRACTOGRAPHY Hydrogen-assisted cracking measurement, test methods, 69-72 Hydrogen embrittlement, 144 HY-100 steel composition, 26 (table) R Roughness, 3, 39 S M Material toughness, 26 Mean stress 123 Mechanical properties of materials, 39, 42 (table) Micromechanical behavior, 26 Microstructures brittle fracture in weldments, 102 effects on fracture behavior, 39 Military aircraft fracture analysis, 53 Mode of fracture, 69 Monotonic loading, 26 Multiaxial fatigue loadings, 123 N Nuclear reactor vessels, 89 O Scanning electron microscope, 52-53, 57, 102 Shear type damage, 123 Silicate particles in weld metals, 97 (table) Steel brittle fracture in weldments 102 mechanical properties, 127 (table) Steel, HT-100, composition, 27 (table) Stereology, Strain energy density, 26 Stress/strain, 123 Surface roughness, T Threshold stress intensity, 69 Tomography, Toughness, 26 102 Transmission electron microscope, 52 Optical microscopy, 57, 102 P Pressure vessel steel, chemical composition, 89, 90 (table) O Quantitative fractography, 4-5, 39, 52 Quasi-cleavage, 69 W Weldments brittle fracture, 102 Weld metals brittle fracture, 102 fractographic study in nuclear pressure vessels, 89 silicate particles, 97 (table) Copyright by ASTM Int'l (all rights reserved); Thu Dec 31 13:55:23 EST 2015 Downloaded/printed by University of Washington (University of Washington) pursuant to License Agreement No further reproductions authorized