Volume 01 - Properties and Selection Irons, Steels, and High-Performance Alloys Episode 8 pps

41L40 85 (b) 185-230 4150 55 (b) 187-240 4340 50 (b) 187-240 4620 65 (c) 183-229 50B40 65 (b) 174-223 50B60 55 (d) 170-212 5130 70 (b) 174-212 5140 65 (b) 179-217 5160 55 (d) 179-217 51B60 55 (d) 179-217 50100 40 (d) 183-240 51100 40 (d) 183-240 52100 40 (d) 183-240 8115 65 (c) 163-202 81B45 65 (b) 179-223 8630 70 (b) 179-229 8620 65 (c) 179-235 86L20 85 (c) . . . 8660 55 (d) 179-217 8645 65 (b) 184-217 86B45 65 (b) 184-217 8740 65 (b) 184-217 (a) Ratings are for cold-finished bars. (b) Microstructure composed of ferrite and lamellar pearlite. (c) Microstructure composed mainly of acicular pearlite and bainite. (d) Microstructure composed primarily of spheroidite Sample Hardness, Heat HB treatment A 206 Spheroidized &fcirc; B 221 Annealed C 321 Normalized D 400 Hardened and tempered E 500 Hardened and tempered F 515 Hardened and tempered Fig. 15 Effect of hardness on tool life curves. Workpiece: 4340 steel. Tool material: C6 carbide. Source: Ref 25 A comparison of the machinability ratings with the compositions of these steels indicates that all of the alloying elements that increase the hardenability of the steel decrease machinability; ferrite-strengthening elements such as nickel and silicon decrease the machinability more than equivalent amounts of carbide-forming elements such as chromium and molybdenum. It is not uncommon for heat-treating considerations to overshadow both machining and material costs in the selection of steel. On occasion, heat-treating responses may dictate the selection of a less machinable or a more expensive steel so that the lowest total costs can be realized. The sulfur content of through-hardening alloy steels can significantly affect machining behavior. Variations in residual sulfur level can account for unexplained differences in the machining behavior of different lots of the same material. Many grades of hardenable alloy steels can be obtained in the resulfurized condition. The differences in tool life and cutting speed between standard and high-sulfur 4150 steels are substantial. Tests by Field and Zlatin (Ref 26) showed that raising the sulfur content from 0.04 to 0.09% increased the cutting speed for 60-min tool life by 25%. Alloy steels containing lead are available and useful. As indicated in Table 6, the machinability rating of the leaded grade 41L40 is 85, while the rating for 4140 is only 65. The performance of these two grades in several machining operations is indicated in Table 7. The data are from a case study described in Ref 26. Table 7 Effect of lead on cutting speed and tool life in machining alloy steels Operation Standard 4140 Leaded 4140 Turning Hardness, HB 300 300 Cutting speed, rev/min 321 495 0.30 0.30 Feed, mm/rev (in./rev) (0.012) (0.012) Tool life, parts per tool grind 4 18-20 Turning Cutting speed, rev/min 460 740 0.15 0.23 Feed, mm/rev (in./rev) (0.006) (0.009) Drilling (a) 8.76 10.55 Cutting speed, m/min (sfm) (28.75) (34.6) 0.10 0.15 Feed, mm/rev (in./rev) (0.004) (0.006) (a) In drilling standard 4140 steel, the 19 mm ( 3 4 in.) diam hole jammed with chips and the drill had to be removed frequently for cleaning. When using leaded 4140 steel, the entire depth was drilled without removing the tool. Another important factor that can affect the choice of steel for a through-hardening application is the effect of alloying elements added for machinability on the mechanical properties of the steel. These steels are often used at high-strength levels, where the deleterious effects of inclusions, particularly on transverse properties, might not be permissible. The effect of sulfur, in the amounts usually specified for enhanced machinability, is generally considered to be more damaging than that of lead. For some applications, neither machinability additive can be tolerated. References cited in this section 25. N. Zlatin and J. Christopher, Machining Characteristics of Difficult to Machine Materials, in Influence of Metallurgy on Machinability, V.A. Tipnis, Ed., American Society for Metals, 1975, p 296-307 26. M. Field and N. Zlatin, Evaluation of Machinability of Rolled Steels, Forgings and Cast Irons, Machining Theory and Practice, American Society for Metals, 1950, p 341-376 Machinability of Steels Francis W. Boulger, Battelle-Columbus Laboratories (retired) Cold-Drawn Steel Cold drawing generally improves the machinability of steels containing less than about 0.2% C. The improvement is most noticeable in plain carbon steels, as shown in Fig. 16. The machinability of higher-carbon steels, or alloy steels, is less affected by cold work. This improvement in machinability may be attributed to reduced cutting forces and/or the characteristics of chip removal. Kopalinsky and Oxley (Ref 28) found that cold drawing lowered the cutting forces and improved the tool life and surface finish of low-carbon steels. Screw machine tests by Yaguchi (Ref 29) showed that the workpiece surface finish improved continuously with increases in reduction in area up to 29%. These effects were not characteristic of steels with high nitrogen contents (Ref 18). The improved machinability of cold-drawn steels can also be attributed to the decrease in ductility that results from cold working; thus, the chips are generally not long and stringy. Fig. 16 Effect of cold drawing on tool life. Workpiece: 1016 steel, 25 mm (1 in.) in diameter. Machining conditions: multiple-operation machined with a cutting speed of 0.73 m/s (144 sfm). Source:Ref 27 Cold-finished bars have closer dimensional tolerances, better surfaces, and usually, higher strength than hot-finished bars. The first two factors may be significant in the selection of steels to be machined in multiple-operation machines or other high-production equipment. These considerations are discussed in the article "Cold-Finished Steel Bars" in this Volume. The machining characteristics of cold-drawn steels are only rarely a decisive criterion for selection. The extra strength obtained with cold-drawn steel may be more important from a cost standpoint, because it is often high enough to eliminate the need for heat treatment. References cited in this section 18. J.D. Watson and R.H. Davies, The Effects of Nitrogen on the Machinability of Low-Carbon Free- Machining Steels, J. Appl. Metalwork., Vol 3 (No. 2), 1984, p 110-119 27. J.D. Armour, Metallurgy and Machinability of Steels, Machining Theory and Practice, American Society for Metals, 1950, p 123-168 28. E.M. Kopalinsky and P.L.B. Oxley, Predicting Effects of Cold Working on Machining Characteristics of Low-Carbon Steels, J. Eng. Ind. (Trans. ASME), Vol 109 (No. 3), 1987, p 257-264 29. H. Yaguchi and N. Onodera, Effect of Cold Working on the Machinabilit y of AISI 12L14 Steel, in Strategies for Automation of Machining: Materials and Processes, Proceedings of an International Conference (Orlando, FL), ASM INTERNATIONAL, 1987, p 15-26 Machinability of Steels Francis W. Boulger, Battelle-Columbus Laboratories (retired) References 1. Machining Data Handbook, 3rd ed., Metcut Research Associates Inc., 1980 2. "Life Tests for Single-Point Tools of Sintered Carbide," B94.36- 1956 (R 1971), American National Standards Institute 3. "Tool Life Testing With Single-Point Turning Tools," ANSI/ASME B94.55M- 1985, American National Standards Institute 4. J.F. Kahles, Elements of the Machining Process, in Metals Handbook: Desk Edition, American Society for Metals, 1985, p 27.10 5. "Machining Performance of Ferrous Metals Using an Automatic Screw/Bar Machine," E 618-81- 03.01, Annual Book of ASTM Standards, American Society for Testing and Materials 6. F.W. Boulger, Influence of Metallurgical Properties on Metal-Cutting Operations, Society of Manufacturing Engineers, 1958 7. F.W. Boulger and H.J. Grover, Machinability Can Be Related to Composition, Tool Eng., Vol 40, March 1958 8. V.C. Venkatesh and V. Narayanan, Machinability Correlations Among Turning, Milling and Drilling Processes, Ann. CIRP, Vol 35 (No. 1), 1986, p 59-62 9. T. Araki et al., Some Results of Cooperative Research on the Effect of Heat Treated Structure on the Machinability of a Low Alloy Steel in Influence of Metallurgy on Machinability, V.A. Tipnis, Ed., American Society for Metals, 1975, p 381-395 10. E.J.A. Armarego and R.H. Brown, The Machining of Metals, Prentice-Hall, 1969 11. J.E. Mayer, Jr., and D.G. Lee, Influence of Machinability on Productivity and Machining Cost, in Influence of Metallurgy on Machinability, V.A. Tipnis, Ed., American Society for Metals, 1975, p 31-54 12. F.W. Boulger et al., Superior Machinability of MX Steel Explained, Iron Age, Vol 167, 17 May 1951, p 90-95 13. W.E. Royer, Making Stainless More Machinable 303 Super X, Autom. Mach., Vol 47 (No. 5), May 1986, p 47-49 14. H. Yaguchi, Effect of MnS Inclusion Size on Machinability of Low-Carbon, Leaded, Resulfurized Free- Machining Steel, J. Appl. Metalwork., Vol 3 (No. 3), July 1986, p 214-225 15. S. Abeyama et al., Development of Free Machining Steel With Controlled-Shape Sulfides, Bull. Jpn. Inst. Met., Vol 24 (No. 6), 1985, p 518-520 16. S. Katayama et al., Improvements in Machinability of Continuously-Cast, Low-Carbon, Free- Cutting Steels, Trans. ISI, Vol 25 (No. 9), Sept 1985, p B229 17. R.M. Welburn and D.J. Naylor, Production and Machinability of Billet- Cast Medium Carbon High Sulfur (Over 0.08%) Free-Machining Steels, in Proceedings of the Conference on Continuous Casting, Institute of Metals, 1985 18. J.D. Watson and R.H. Davies, The Effects of Nitrogen on the Machinability of Low-Carbon Free- Machining Steels, J. Appl. Metalwork., Vol 3 (No. 2), 1984, p 110-119 19. H.J. Tata and R.E. Sampsell, Effects of Additions on Machinability and Properties of Alloy- Steels Bars, Paper 730114, Trans. SAE, Vol 82, 1973 20. R.A. Joseph and V.A. Tipnis, The Influence of Non-Metallic Inclusions on the Machinability of Free- Machining Steels, in Influence of Metallurgy on Machinability, V.A. Tipnis Ed., American Society for Metals, 1975, p 55-72 21. S.V. Subramanian and D.A.R. Kay , Inclusions and Matrix Effects on the Machinability of Medium Carbon Steels, in Conference Proceedings, Ottawa, Ontario, Canada, Canadian Government Publishing Centre, 1985 22. T. Kato, S. Abeyama, A. Kimura, and S. Nakamura, The Effect of Ca Oxide Inclu sions on the Machinability of Heavy Duty Steels, in The Machinability of Engineering Materials, R.W. Thompson, Ed., Conference Proceedings, 13-15 Sept (Rosemont, IL), American Society for Metals, 1983, p 323-337 23. J. Fombarlet, Improvement in the Machin ability of Engineering Steels Through Modification of Oxide Inclusions, in The Machinability of Engineering Materials, 13- 15 Sept (Rosemont, IL), R.W. Thompson, Ed., Conference Proceedings, American Society for Metals, 1983, p 366-382 24. B Reh, U. Finger et al., Development of Bismuth- Alloyed High Performance Easy Machining Steel, Neue Hütte, Vol 31 (No. 9), Sept 1986, p 327-330 25. N. Zlatin and J. Christopher, Machining Characteristics of Difficult to Machine Materials, in Influence of Metallurgy on Machinability, V.A. Tipnis, Ed., American Society for Metals, 1975, p 296-307 26. M. Field and N. Zlatin, Evaluation of Machinability of Rolled Steels, Forgings and Cast Irons, Machining- -Theory and Practice, American Society for Metals, 1950, p 341-376 27. J.D. Armour, Metallurgy and Machinability of Steels, Machining Theory and Practice, American Society for Metals, 1950, p 123-168 28. E.M. Kopalinsky and P.L.B. Oxley, Predicting Effects of Cold Working on Machining Characteristics of Low-Carbon Steels, J. Eng. Ind. (Trans. ASME), Vol 109 (No. 3), 1987, p 257-264 29. H. Yaguchi and N. Onodera, Effect of Cold Working on the Machinability of AISI 12L14 Steel, in Strategies for Automation of Machining: Materials and Processes, Proceedings of an Internation al Conference (Orlando, FL), ASM INTERNATIONAL, 1987, p 15-26 Weldability of Steels S. Liu, Center for Welding and Joining Research, Colorado School of Mines; J.E. Indacochea, Department of Civil Engineering, Mechanics, and Metallurgy, University of Illinois at Chicago Introduction THE MAIN OBJECTIVE of this article is to survey the factors controlling the weldability of carbon and low-alloy steels in arc welding. A good understanding of the chemical and physical phenomena that occur in the weldment is necessary for welding modern steels. Therefore, the influence of operational parameters, thermal cycles, and metallurgical factors on weld metal transformations and the susceptibility to hot and cold cracking are discussed. Common tests to determine steel weldability are also described. The carbon and low-alloy steels group comprises a large number of steels that differ in chemical composition, strength, heat treatment, corrosion resistance, and weldability. These steels can be further divided into subgroups: • Carbon steels • High-strength low-alloy (HSLA) steels • Quenched and tempered (QT) steels • Heat-treatable low-alloy (HTLA) steels • Precoated steels This article addresses only the basic principles that affect the weldability of carbon and low-alloy steels. More detailed information concerning the other aspects of welding, such as joint design, defects, and failure in weldments and the influence of these factors on different groups of steels, can be found in Volumes 1and 6 of the 9th Edition Metals Handbook and Volume 11 of ASM Handbook, formerly 9th Edition Metals Handbook and in the "Selected References" at the end of this article. Weldability of Steels S. Liu, Center for Welding and Joining Research, Colorado School of Mines; J.E. Indacochea, Department of Civil Engineering, Mechanics, and Metallurgy, University of Illinois at Chicago Characteristic Features of Welds Single-Pass Weldments. To understand weldability, it is necessary to recognize the various weld regions. In the case of a single-pass bead, the weldment is generally divided into two main regions: the fusion zone, or weld metal, and the heat-affected zone (HAZ), as shown in Fig. 1. Within the fusion zone, the peak temperature exceeds the melting point of the base metal, and the chemical composition of the weld metal will depend on the choice of welding consumables, the base metal dilution ration, and the operating conditions. Fig. 1 Various regions of a bead-on-plate weld Under conditions of rapid cooling and solidification in the weld metal, alloying and impurity elements segregate extensively to the center of the interdendritic or intercellular regions and to the center parts of the weld, resulting in significant local chemical inhomogeneities. Accordingly, the transformation behavior of the weld metal may be quite different from that of the base metal, even when the bulk chemical composition is not significantly changed by the welding process. The typical anisotropic nature of the solidified weld and structure is also shown in Fig. 1. The chemical composition remains largely unchanged in the HAZ because the peak temperature remains below the melting point of the parent plate. Nevertheless, considerable microstructural change takes place within the HAZ during welding as a result of the extremely harsh thermal cycles. The material immediately adjacent to the fusion zone is heated high into the austenitic temperature range. The microalloy precipitates that development in the previous stages of processing will generally dissolve, and unpinning of austenite grain boundaries occurs with substantial growth of the grains, forming the coarse-grain HAZ. The average size of the austenite grains, which is a function of the peak temperature attained, decrease with increasing distance from the fusion zone. The cooling rate also varies from point to point in the HAZ; it increases with increasing peak temperature at constant heat input and decreases with increasing heat input at constant peak temperature. Because of varying thermal conditions as a function of distance from the fusion line, the HAZ is actually composed of coarse-grain zones (CGHAZ), fine-grain zones (FGHAZ), intercritical zones (ICHAZ), and subcritical zones (SCHAZ). The various HAZ regions of a single-pass low-carbon steel butt weld are shown in Fig. 2. Fig. 2 Various regions of the HAZ of a single-pass low-carbon steel weld metal with 0.15 wt% C In multipass weldments, the situation is much more complex because of the presence of reheated zones within the fusion zone, as shown in Fig. 3. The partial refinement of the microstructure by subsequent weld passes increases the inhomogeneity of the various regions with respect to microstructure and mechanical properties. Reaustenitization and subcritical heating can have a profound effect on the subsequent structures and properties of the HAZ. Toughness property deterioration is related to small regions of limited ductility and low cleavage resistance within the CGHAZ that are known as the localized brittle zones (LBZ). Localized brittle zones consist of unaltered CGHAZ, intercritically reheated coarse-grain (IRCG) heat-affected zone, and subcritically reheated coarse-grain (SRCG) heat-affected zone. At an adjacent fusion line, that LBZs may be aligned, as shown in Fig. 3. The aligned LBZs offer short and easy paths for crack propagation. Fracture occurs along the fusion line. Fig. 3 Overlapping of HAZ to form localized brittle zones aligned along the fusion line Weldability of Steels S. Liu, Center for Welding and Joining Research, Colorado School of Mines; J.E. Indacochea, Department of Civil Engineering, Mechanics, and Metallurgy, University of Illinois at Chicago Metallurgical Factors That Affect Weldability Hardenability and Weldability. Hardenability in steels is generally used to indicate austenite stability with alloy additions. However, it has also been used as an indicator of weldability and as a guide for selection a material and welding process to avoid excessive hardness and cracking in the HAZ. Steels with high hardness often contain a high [...]... 51 5-6 20 7 5-9 0 290 42 16(d) 44 5-5 30 6 5-7 7 255 37 19(d), 23 Tensile strength Yield strength, minimum MPa ksi MPa ksi SA-106A 330 48( a) 207 SA-106B 415 60(a) SA- 285 A 31 0-3 80 SA-299 SA-204A SA-302A 51 5-6 55 7 5-9 5 310 45 15(d), 19 SA-533B2 62 0-7 90 9 0-1 15 475 70 16 SA-517F 79 5-9 30 11 5-1 35 690 100 16 3 4-4 5 SA-335P12 415 60(a) 207 30 30(b), 20(c) SA-217WC6 48 5-6 20 7 0-9 0 275 40 20 35 SA- 387 Gr2 2-1 41 5-5 85 ... SA-106B K01700 C-Si Seamless carbon steel pipe 0.30(a) 0.291.06 0.10(b) 0.0 48( a) 0.0 58( a) SA- 285 A K03006 C Carbon steel PV plate 0.17(a) 0.90(a) 0.035(a) 0.045(a) 0.25 Cu(a) SA-299 K0 280 3 C-Mn-Si C-Mn-Si steel PV plate 0. 28( a) 0. 901. 40 0.150.30 0.035(a) 0.040(a) SA-204A K1 182 0 1 Mo 2 Mo alloy steel PV plate 0. 18( a) 0.90(a) 0.150.30 0.035(a) 0.040(a) 0.450.60 SA-302A K12021 Mn-Mo... 0.045(a) 8 .01. 0 0. 901. 20 1 Mo 2 SA- 387 Gr22 K21590 SA- 387 Gr5 S 5010 0 SA-217C12 J82090 2 1 Cr-1Mo 4 5Cr- 1 Mo 2 9Cr-1Mo (a) Maximum (b) Minimum Table 3(2) Room-temperature mechanical properties of steels for elevated-temperature service listed in Table 3(1) ASME specification Mechanical properties Minimum elongation in 50 mm (2 in.), % Minimum reduction in area, % 30 35(b), 25(c) 241 35 30(b), 16.5(c) 4 5-5 5... Society, 1 987 , p 25 5-2 62 H Suzuki "Carbon Equivalent and Maximum Hardness," DOC IX-127 9 -8 3, International Institute of Welding, 1 983 Welding, Brazing, and Soldering, Vol 6, 9th ed., Metals Handbook, American Society for Metals, 1 983 Welding Handbook, Vol I and II, 7th ed., American Welding Society, 1 983 Elevated-Temperature Properties of Ferritic Steels Introduction CARBON STEELS and low-alloy steels... 41 5-5 85 6 0 -8 5 207 30 18( d), 45 40 SA- 387 Gr 5-2 51 5-6 90 7 5-1 00 310 45 18( d), 22 45 SA-217C12 62 0-7 95 9 0-1 15 415 60 18 35 (a) Minimum (b) Longitudinal (c) Transverse (d) Elongation in 200 mm (8 in.) Aerospace material specifications, as the name suggests, are specifications for products intended for the aerospace industry The nominal compositions, typical applications, and typical mechanical properties. .. rotors and aircraft parts 0.27 0.75 0.65 1.25 0.50 0 .85 610 6437, 6 485 H11 mod T2 081 1 K7 4015 AISI designation Room-temperature tensile properties Yield strength Tensile strength Elongation in 50 mm (2 in.), % MPa ksi MPa 710 103 85 5 124 29 602 745930 1 081 35 8 80 10 60 1 281 54 603 1000 145 1100 610 1 480 215 180 5 0.40 0.30 0.90 5.00 1.30 0.50 Temperature at which 70 MPa (10 ksi) will cause rupture in ksi 601. .. Mn-Mo Mn-MoMn and Mo-Ni alloy PV plate 0.20(a) 0.951.30 0.150.30 0.035(a) 0.040(a) 0.450.60 SA-533B2 K12539 Mn-Mo-Ni Mn-MoMn and Mo-Ni alloy steel PV plate 0.25(a) 1.151.50 0.150.30 0.035(a) 0.040(a) 0.400.70 0.450.60 0.10 Cu(a) SA-517F K11576 Highstrength alloy steel PV plate 0.100.20 0. 601. 00 0.150.35 0.035(a) 0.040(a) 0.400.65 0. 701. 00 0.400.60 0.0020.006 B, 0.150.050 Cu, 0.030. 08 V C- SA-335... (No 12), 1 984 , p 74 0-7 43 C.E Cross, Ø Grong, S Liu, and J.F Capes, Metallography and Welding Process Control, in Applied Metallography, G Vander Voort, Ed., Van Nostrand Reinhold, 1 985 G.J Davies and J.G Garland, Solidification Structures and Properties of Fusion Welds, Int Met Rev., No 20, 1975, p 8 3-1 06 K Easterling, Introduction to the Physical Metallurgy of Welding, Butterworths, 1 983 D.P Fairchild,... "High-Strength Structural and High-Strength Low-Alloy Steels" in this Volume, may be effective substitutes for carbon steels in elevated-temperature applications Another category of ferritic steels for elevated-temperature service are manganese-molybdenum-nickel ferritic steels (ASTM A 302 and A 533), which are commonly used for pressure vessels in light-water reactors High-alloy steels, stainless steels,. .. light-water reactors High-alloy steels, stainless steels, hot-work tool steels, and the iron-base superalloys are discussed in the Section "Specialty Steels and Heat-Resistant Alloys" in this Volume Alloy Designations and Specifications Carbon and low-alloy steels used for elevated-temperature service are usually identified by American Iron and Steel Institute (AISI) designations; aerospace material . 55 (d) 17 9-2 17 51B60 55 (d) 17 9-2 17 5010 0 40 (d) 18 3-2 40 51100 40 (d) 18 3-2 40 52100 40 (d) 18 3-2 40 81 15 65 (c) 16 3-2 02 81 B45 65 (b) 17 9-2 23 86 30 70 (b) 17 9-2 29 86 20 65 (c) . 17 9-2 29 86 20 65 (c) 17 9-2 35 86 L20 85 (c) . . . 86 60 55 (d) 17 9-2 17 86 45 65 (b) 18 4-2 17 86 B45 65 (b) 18 4-2 17 87 40 65 (b) 18 4-2 17 (a) Ratings are for cold-finished bars. (b). 41L40 85 (b) 18 5-2 30 4150 55 (b) 18 7-2 40 4340 50 (b) 18 7-2 40 4620 65 (c) 18 3-2 29 50B40 65 (b) 17 4-2 23 50B60 55 (d) 17 0-2 12 5130 70 (b) 17 4-2 12 5140 65 (b) 17 9-2 17