Volume 16 - Machining Part 4 pdf

Fig. 35 Proprietary 55° parallelogram carbide insert An undesirable by-product of thread machining is the V-shaped chip removed from the workpiece. Indexable inserts with proprietary chip control geometries molded into the top rake surface of the cutting edge are becoming available, and they control and break the chips with varying levels of success. In the more common thread forms, multitooth thread-chasing inserts are available as a means of reducing the number of passes required to complete a thread, thus improving productivity (Fig. 36). An increasingly popular option available for many thread forms is the cresting insert, which machines the full thread form. Noncresting inserts machine the root and flanks but not the crest of the thread. Fig. 36 A multitooth thread-chasing insert Thread milling, a thread machining method that is useful when turning is not possible, is performed on multiaxis computer numerical control machines capable of helical interpolation (Fig. 37). A disadvantage of thread milling is that the thread form it produces is slightly imperfect because of the inability of the cutting tool to clear the helical angle of the thread form as it exits the part. However, the threads are sufficiently accurate for all but the most demanding applications. Fig. 37 Thread milling with indexable inserts Grooving. There are three different grooving insert styles in common use: • 90° V-bottom (Fig. 38) • Proprietary stand-up 55° parallelogram (Fig. 35) • Stand-up (on-edge) triangle The V-bottom system is the most suitable for deep grooving because the cutting edge of the insert is wider than the body and is directly supported by the toolholder. The compact design and proprietary clamping method of the 55° parallelogram system maximize rigidity in shallow grooving. The on-edge triangle system offers three cutting edges on each insert, as opposed to two in the other common grooving systems. Chip control is a major concern in grooving, and products are becoming available that control and/or break chips with varying levels of success. Fig. 38 90° V-bottom (dogbone) grooving inserts and toolholders Cutoff. The early carbide cutoff tools consisted of carbide inserts brazed onto steel shanks. As in the case of carbide turning inserts, efforts to eliminate tool re-sharpening costs and to improve performance led to the development of mechanically held replaceable cutoff inserts. These inserts are available in a variety of styles, but most have a vee shape in the top or bottom surface, which is gripped by the steel holder for rigidity. Most cutoff inserts have a single cutting edge and are held either by clamping or by wedging directly into the holder. Chip control is available in either molded or ground geometries (Fig. 39). Fig. 39 Cutoff inserts and toolholders Machining Applications Uncoated Straight WC-Co Grades. Despite the advent of coated cemented carbide tools in the late 1970s, uncoated straight WC-Co grades still find a place in many machining operations. Unalloyed gray cast iron is probably the most common workpiece material machined with WC-Co grades, but other materials such as high-temperature alloys, austenitic stainless steels, nonferrous alloys, and nonmetals are often machined with C1 and/or C2 grades. The recommended speed and feed ranges for these materials are listed in Table 9. The higher-cobalt C1 grades are also often used on difficult-to-machine workpieces, such as chilled cast iron and heat-treated steels, where cutting tool strength and shock resistance are important. High-temperature alloys and austenitic stainless steels are machined with C2 grades, typically in positive-rake, sharp-edge geometries at lower surface speeds. Table 9 Recommended speed and feed ranges for uncoated straight WC-Co grades Roughing (a) Finishing (b) Speed Feed Speed Feed Material Hardness, HB Recommended grade m/min sfm mm/rev in./rev m/min sfm mm/rev in./rev 190-330 C2 99- 168 325- 550 0.10- 0.36 0.004- 0.014 122- 213 400- 700 0.10- 0.38 0.004- 0.015 330-450 C2 84- 137 275- 450 0.08- 0.25 0.003- 0.010 91-183 300- 600 0.08- 0.30 0.003- 0.012 Gray cast iron 450-700 C1 68- 106 225- 350 0.05- 0.15 0.002- 0.006 91-137 300- 450 0.05- 0.25 0.002- 0.010 120-180 C2 68- 106 225- 350 0.15- 0.41 0.006- 0.016 84-137 275- 450 0.13- 0.51 0.005- 0.020 Austenitic stainless steel 180-240 C2 61-91 200- 300 0.08- 0.30 0.003- 0.012 68-122 225- 400 0.08- 0.38 0.003- 0.015 150-250 C2 18-43 60- 140 0.13- 0.25 0.005- 0.010 23-61 75-200 0.08- 0.30 0.003- 0.012 High-temperature alloys 250-400 C2 15-34 50- 110 0.08- 0.20 0.003- 0.008 18-43 60-140 0.05- 0.23 0.002- 0.009 Nonferrous materials 80-120 C2 61- 244 200- 800 0.20- 0.51 0.008- 0.020 91-366 300- 1200 0.13- 0.30 0.005- 0.012 Nonmetals . . . C2 76-250-0.20-0.008-152-500-0.13-0.005- (a) Depth of cut greater than 2.5 mm (0.100 in.). (b) Depth of cut less than 2.5 mm (0.100 in.) Uncoated alloyed carbide grades (C5 to C8 carbide classifications) are primarily used in machining steels in the speed and feed ranges listed in Table 10. Uncoated alloyed carbides are well suited to a number of machining applications. They are widely used when machines do not have sufficient horsepower to utilize the high metal removal capabilities of advanced coated tools. Uncoated carbides also find application in brazed form tools, which are typically made with highly specialized geometries mirroring the part being machined. Table 10 Recommended speed and feed ranges for uncoated alloyed carbide grades Roughing (a) Finishing (b) Speed Feed Speed Feed Material Hardness, HB Recommended grade m/min sfm mm/rev in./rev m/min sfm mm/rev in./rev 140-190 C5, C6 76- 122 250- 400 0.30- 0.64 0.012- 0.025 106- 168 350- 550 0.13- 0.38 0.005- 0.015 Free-machining steels 190-240 C5, C6 61- 106 200- 350 0.20- 0.51 0.008- 0.020 91-152 300- 500 0.08- 0.30 0.003- 0.012 Plain carbon 185-240 C5, C6 61- 106 200- 350 0.20- 0.51 0.008- 0.020 91-137 300- 450 0.13- 0.51 0.005- 0.020 190-330 C5 61- 106 200- 350 0.30- 0.64 0.012- 0.025 91-122 300- 400 0.13- 0.51 0.005- 0.020 330-450 C5 53-91 175- 300 0.25- 0.51 0.010- 0.020 76-106 250- 350 0.10- 0.41 0.004- 0.016 Alloy steels 450-700 C7 38-76 125- 250 0.15- 0.38 0.006- 0.015 46-91 150- 300 0.08- 0.30 0.003- 0.012 400, 500 series stainless steel 175-210 C5 46- 106 150- 350 0.25- 0.64 0.010- 0.025 91-152 300- 500 0.10- 0.51 0.004- 0.020 (a) Depth of cut greater than 3.2 mm (0.125 in.). (b) Depth of cut less than 3.2 mm (0.125 in.) Uncoated alloyed carbides are also employed in the machining of special part configurations with thin wall sections and tight tolerances. These parts cannot be subjected to high forces during machining. The CVD-coated tools, which are honed prior to coating, are not effective in these applications, for which high positive, sharp-edged, uncoated alloyed carbides are a better choice. The recently developed PVD-coated inserts with sharp edges may prove effective in such applications. Coated carbide grades provide more abrasion resistance to the tool and permit the use of higher machining speeds and feeds. This is illustrated in the tool life diagram shown in Fig. 40, which compares the performance of a C5 grade with and without TiC-TiCN-TiN coating in turning SAE 1045 steel. Fig. 40 Tool life comparison of a coated and an uncoated carbide tool. Constant tool life (15 min) plot for an uncoated and a TiC-TiCN-TiN-coated C5 grade in turning SAE 1045 steel. The depth of cut was 2.5 mm (0.100 in.). More than 50% of the metal cutting inserts currently sold in the United States are CVD coated. These coatings are used in a wide range of machining applications, including turning, milling, threading, and grooving. Physical vapor deposited coatings can be applied to sharp insert edges without the deleterious effect of phase formation. The sharp, tough PVD inserts are particularly well suited to milling applications; they have also been found to perform well in threading and grooving operations on difficult-to-machine materials such as high-temperature alloys and austenitic stainless steels. Submicron Grades for Aerospace Materials. Although new cutting tool materials such as Sialons and whisker- reinforced ceramics have provided great increases in machining productivity on nickel-base alloys, similar improvements have not occurred in the machining of titanium alloys. However, submicron (fine-grain) carbide grades have shown the capacity to enhance productivity in both titanium alloys and the nickel-base materials. In general, the strength or toughness of a carbide grade is inversely proportional to its abrasion resistance. The microstructures associated with submicron carbide materials provide both strength and abrasion resistance. In titanium turning operations where speed and feed parameters are held constant, tool life improvements of 200% have been recorded after a change to submicron carbide cutting tool materials. References 1. H. Moissan, The Electrical Furnace, V. Lenher, Trans., Chemical Publishing Company, 1904 2. E.K. Storms, The Refractory Carbides, Academic Press, 1978 3. M. Hansen and K. Anderko, Constitution of Binary Alloys, McGraw-Hill, 1958 4. K. Schroeter, U.S. Patent 1,549,615, 1925 5. E.M. Trent, Cutting Tool Materials, Metall. Rev., Vol 13 (No. 127), 1948, p 129-144 6. K.J.A. Brookes, World Directory and Handbook of Hardmetals, 4th ed., International Carbide Data, 1987 7. E. Lardner, Powder Metall., Vol 21, 1978, p 65 8. H.E. Exner, Int. Met. Rev., Vol 24 (No. 4), 1979, p 149-173 9. P.M. McKenna, U.S. Patent 3,379,503, 1968 10. P.M. McKenna, Tool Materials Cemented Carbides, in Powder Metallurgy, J. Wulff, Ed., 1942, p 454-469 11. H.D. Hanes, D.A. Seifert, and C.R. Watts, Hot Isostatic Processing, Battelle Press, 1979, p 20-24 12. R.C. Lueth, Advances in Hardmetal Production, in Proceedings of the Metal Powder Report Conference (Luzern), Vol 2, MPR Publishing Services Ltd., 1983 13. P.A. Dearnley, Met. Technol., Vol 10, 1983 14. H. Tanaka, Relationship Between the Thermal, Mechanical Properties and Cutting Performance of TiN- TiC Cermet, in Cutting Tool Materials, Conference Proceedings, American Society for Metals, 1981, p 349-361 15. R.C. Lueth, Fracture Mechanics of Ceramics, R.C. Bradt et al., Ed, Plenum Press, 1974, p 791-806 16. J.L. Chermant and F. Osterstock, J. Mater. Sci., Vol 11, 1976, p 1939-1951 17. J.R. Pickens and J. Gurland, Mater. Sci. Eng., Vol 33, 1978, p 135-142 18. W.D. Kingery, H.K. Bowen, and D.R. Uhlmann, Introduction to Ceramics, 2nd ed., John Wiley & Sons, 1960, p 828 19. C.S. Ekmar, German Patent 2,007,427 20. W. Schintlmeister, O. Pacher, and K. Pfaffinger, in Chemical Vapor Deposition, Fifth International Conference, J.M. Blocker, Jr. et al., Ed., T he Electrochemical Society Softbound Symposium Series, Electrochemical Society, 1975, p 523 21. W. Schintlmeister, O. Pacher, K. Pfaffinger, and T. Raine, J. Electrochem. Soc., Vol 123, 1976, p 924-929 22. V.K. Sarin and J.N. Lindstorm, J. Electrochem. Soc., Vol 126, 1979, p 1281-1287 23. W. Schintlmeister, W. Wallgram, J. Ganz, and K. Gigl, Wear, Vol 100, 1984, p 153-169 24. B.N. Kramer and P.K. Judd, J. Vac. Sci. Technol., Vol A3 (No. 6), 1985, p 2439-2444 25. T.E. Hale, Paper presented at the Intern ational Machine Tool Show Technical Conference, National Machine Tools Builders Association, 1982 26. H.E. Hintermann, Wear, Vol 100, 1984, p 381-397 27. B.J. Nemeth, A.T. Santhanam, and G.P. Grab, in Proceedings of the Tenth Plansee Seminar (Reutte/Tyro l), Metallwerk Plansee A.G., 1981, p 613-627 28. A.T. Santhanam, G.P. Grab, G.A. Rolka, and P. Tierney, An Advanced Cobalt- Enriched Grade Designed to Enhance Machining Productivity, in High Productivity Machining Materials and Processes, Conference Proceedings, American Society for Metals, 1985, p 113-121 29. R.F. Bunshah and A.C. Raghuram, J. Vac. Sci. Technol., Vol 9, 1972, p 1385 30. G.J. Wolfe, C.J. Petrosky, and D.T. Quinto, J. Vac. Sci. Technol., Vol A4 (No. 6), 1986, p 2747-2754 31. D.T. Quinto, G.J. Wolfe, and P.C. Jindal, Thin Solid Films, the International Conference on Metallic Coatings, Vol 153, 1987, p 19-36 32. D.T. Quinto, C.J. Petrosky, and J.L. Hunt, Cutting Tool Eng., Vol 39, 1987, p 46-52 Cermets Walter W. Gruss, Kyocera Feldmuehle, Inc. Introduction CERMETS are a group of powder metallurgy products consisting of ceramic particles bonded with a metal. The ceramic component of cermets provides high hot hardness and oxidation resistance, while the metallic component enhances ductility and thermal shock resistance. The bonding of ceramic components with metals, a complex process, depends largely on the solubility, wetting properties, and phase relations of the selected materials. Composition and Microstructure Ceramics are defined as any class of inorganic or nonmetallic products that are subjected to high temperature during manufacture or use (Ref 1). Typically, but not exclusively, a ceramic is a metallic oxide, boride, or carbide, or a mixture or compound of such materials. By this definition of ceramics, the following materials theoretically fall into the group of cermets: • WC + Co (Tungsten carbide + cobalt) • WC/TiC/TaC + Co (Tungsten carbide/titanium carbide/tantalum carbide + cobalt) • TiC + Ni (Titanium carbide + nickel) • Ti(C,N) + Ni/Mo (Titanium carbonitride + nickel/molybdenum) However, the cutting tool industry considers only the titanium carbide and titanium carbonitride base materials to be cermets, while the tungsten carbide based materials are named cemented carbides. Therefore, this article will concentrate on cermets based on titanium carbide and titanium carbonitride. Titanium Carbide Cermets. The first attempts to apply titanium carbide in sintered, tungsten-free cutting tool materials were made in Germany in 1929, when titanium carbide/molybdenum carbide solid solutions with 15% nickel as binder were manufactured and applied for finish turning of steel (Ref 2). Acceptance was limited because of the low strength and high brittleness of this material. However, the interest in titanium carbide continued, mainly due to the lower cost and availability of its raw material, titanium oxide (TiO 2 ). Also, the higher hardness, melting point, and oxidation resistance of titanium carbide (TiC) compared to that of tungsten carbide (WC) promised greater potential. The poor wettability of titanium carbide (TiC) with nickel (Ni) was improved drastically with the addition of molybdenum (Mo) or molybdenum carbide (Mo 2 C) to the nickel binder phase (Ref 3). The microstructure of such a composition is shown schematically in Fig. 1. The core of the carbide phase consists of titanium carbide ( 1 -phase), while the rim is enriched with molybdenum carbide ( 2 -phase) (Ref 4 and 5). The molybdenum from the binder phase diffuses into the carbide phase and improves wettability by means of the metal binder. The abrasion resistance of such a composition varies with the sintering temperature (Fig. 2). Fig. 1 Schematic of cermet microstructure Fig. 2 Flank wear of titanium carbide cermet sintered at different temperatures. Machining parameters: feed, 0.28 mm/rev (0.011 in./rev); depth of cut, 2.5 mm (0.100 in.); speed, 106 m/min (350 sfm). Workpiece: 1045 steel (163 to 174 HB) Cermets Based on Metal Carbonitrides. The development of cermets continued with the introduction of metal carbonitrides. Titanium-molybdenum-carbon-nitrogen and titanium-tungsten-carbon-nitrogen compounds with metal binders, preferably consisting of nickel, molybdenum, cobalt, or a combination thereof, gained specific attention. Considerable improvement was achieved when the carbonitride phase had a composition within the parameters described in Fig. 3. Fig. 3 Preferred compositions of titanium carbonitride cermets. M, molybdenum and/or tungsten; z , number of moles carbon and nitrogen divided by the number of moles titanium and M; z i s variable between the limits 0.80 and 1.07. Source: Ref 6 The microstructure of such a material is shown in Fig. 1. It is possible to observe a core/rim microstructure of the carbonitride phase, with the 1 -phase of the core consisting of titanium carbonitride and the 2 -phase of the rim being enriched with molybdenum carbide and/or tungsten carbide (Ref 4). The nitrogen additions to the hard phase resulted in higher wear resistance (Fig. 4) and reduced plastic deformation of the cutting edge (Fig. 5). Additions of cobalt to the binder phase and of tantalum and/or niobium to the hard phase of complex metal carbonitrides also can improve the cutting performance of cermets. The high-temperature properties of a complex metal carbonitride is compared with a titanium carbide cermet in Table 1. Table 1 Comparison of high-temperature properties of a TiC cermet and a complex carbonitride cermet Transverse rupture strength at 900 °C (1650 °F) Composition of cermet Vickers hardness at 1000 °C (2000 °F), kg/mm 2 MPa ksi Oxidation resistance at 1000 °C (2000 °F) weight gain, mg/cm 2 · h Thermal conductivity at 1000 °C (2000 °F), W/K 6 · m TiC-16.5Ni-9Mo 500 1050 152 11.8 24.7 Fig. 4 Comparison of flank wear for two cermets and a cemented carbide when turning 4340 steel. Source: Ref 6 Fig. 5 Effect of titanium nitride addition on the plastic deformation of a cutting edge. Workpiece, 4340 steel (300 HB). Source: Ref 7 Properties and Grade Selection The manufacturers of cutting tool materials treat the compositions and properties of their grades as proprietary. The commercially available grades fall into two categories: the titanium carbide base cermets and the titanium carbonitride base cermets. The titanium carbide base cermet grades are in the process of being replaced by the titanium carbonitride base cermet grades because of their higher wear resistance (Fig. 4), hardness, and transverse rupture strength (Fig. 6). Typical properties of titanium carbonitride cermets are shown in Table 2. [...]... figures-of-merit for thermal shock resistance Table 2 Room-temperature properties of ceramic and tungsten carbide tool materials Tool material Transverse rupture strength MPa ksi Hardness, HRA Al2O3 Al2O3-ZrO2 Al2O3-TiC Al2O3-SiCw Si3N4 SiAlON WC-Co alloys 50 0-7 00 70 0-9 00 60 0-8 50 55 0-7 50 70 0-1 050 70 0-9 00 125 0-2 100 9 3-9 4 9 3-9 4 9 4- 9 5 9 4- 9 5 9 2-9 4 9 3-9 5 9 1-9 3 7 0-1 00 10 0-1 30 9 0-1 20 8 0-1 10 10 0-1 50 10 0-1 25 18 0-3 00... Fracture toughness MPa 3. 5 -4 .5 5. 0-8 .0 3. 5 -4 .5 4. 5-8 .0 6. 0-8 .5 4. 5-6 .0 10. 0-1 3.5 ksi 3. 2 -4 .1 4. 5-7 .3 3. 2 -4 .1 4. 1-7 .3 5. 5-7 .7 4. 1-5 .5 9. 1-1 1 .4 Fig 8 Thermal shock figures-of-merit Thermal conductivity, k, at 500 °C (930 °F); , expansion coefficient, 25 to 870 °C (80 to 160 0 °F) range Sialon I and II are defined in Fig 7 Source: Ref 19 The importance of these properties depends on the machining conditions... Roughing 45 (150) 110 (360) 146 (48 0) 320 Finishing 45 (150) 137 (45 0) 183 (600) Nodular cast irons Roughing 75 (250) 120 (40 0) 213 (700) 140 Finishing 120 (40 0) 213 (700) 300 (1000) Roughing 160 (200) 110 (360) 167 (550) 250 Finishing 120 (40 0) 150 (500) 245 (800) Roughing 45 (150) 98 (320) 150 (500) 320 Finishing 160 (200) 120 (40 0) 183 (600) Roughing 45 (150) 85 (280) 137 (45 0) 380 Finishing 160 (200)... Carbon steels 200 650 150 183 600 200 1 74 570 250 165 540 300 150 500 350 Alloy steels 183 600 150 150 500 250 120 40 0 350 120 40 0 40 0 Stainless steels, 40 0 series (martensitic, ferritic) 143 47 0 150 137 45 0 200 120 40 0 350 Stainless steels, 300 series (austenitic) 120 40 0 200 113 370 250 107 350 350 Tool steels 165 540 150 150 500 200 137 45 0 250 120 40 0 300 Table 9 In-feed recommendations for threading... (0.00 4) 0.10 0.07 (0.00 3) 0.10 0.03 (0.00 1) 0.05 0.03 24 0.1 3 0.00 5 0.7 1 0.02 8 6 20 0.1 5 0.00 6 0.8 6 0.03 4 7 18 0.1 8 0.00 7 0.9 4 0.03 7 8 16 0.2 0 0.00 8 1.0 4 0. 04 1 9 14 0.2 3 0.00 9 1.1 9 0. 04 7 10 12 0.2 5 0.01 0 1 .4 0 0.05 5 11 Internal threads per 25 mm (1 in.) 0.0 0.00 0.7 0.03 7 20 8 3 8 1 18 0.0 0.00 0.8 0.03 8 8 3 9 5 16 0.1 0 0.00 4 0.9 7 0.03 8 9 14 0.1 0 0.00 4 1.1 2 0. 04 4 10... (600) 245 (800) 0 .46 (0.018) 0 .41 (0. 016) 0 .41 (0. 016) 0.38 (0.015) 0.38 (0.015) 0.30 (0.012) 0.300 150 (500) 50 (160 ) 0 .41 (0. 016) 0.33 (0.013) 0.36 (0.0 14) 0.30 (0.012) 0.30 (0.012) 0.25 (0.010) 7.6 Semifinishing, finishing Roughing 0.23 (0.009) 0.20 (0.008) 0.15 (0.006) 0.15 (0.006) 0.15 (0.006) 0.10 (0.0 04) 2.5 0.100 Tool steels 100 Roughing 220 (720) 275 (900) 275 (900) 0.100 165 ( 540 ) 245 (800)... Table 7 Machining parameters for the grooving of various steels with cermet tools Feed rate, 0.05 to 0.13 mm/rev maximum (0.002 to 0.005 in./rev maximum) Hardness, HB Cutting speed, median m/min sfm Carbon steels 230 750 150 2 04 670 200 183 600 250 165 540 300 146 48 0 350 Alloy steels 213 700 150 1 74 570 250 146 48 0 350 120 40 0 40 0 Stainless steels, 40 0 series (martensitic, ferritic) 170 560 150 137 45 0... temperature to form an oxynitride liquid phase in which -Si3N4 dissolves and from which -Si3N4 is precipitated SiAlON generally refers to a system made up of Al2O3 and Si3N4 The -SiAlONs are derived from the structure of - Si3N4 (hexagonal crystal structure with ABAB stacking) having compositions of Si6-xAlxOxN8-x (O x 4. 2) The SiAlONs are derived from the -Si3N4 structure (hexagonal crystal structure with ABCDABCD... 3.8 4. 7 3.2 2.5 2.5 2.5 2.5 0.250 0.150 0.187 0.125 0.100 0.100 0.100 0.100 Table 6 Machining parameters with cermet tools in the turning of nonferrous free -machining metals Hardness, HB Operation Cutting speed, m/min (sfm) Feed rate, mm/rev (in./rev) Low Median High Low Nonferrous free -machining alloys (aluminum, brass, bronze, copper, magnesium, zinc) Roughing 44 0 49 0 730 0.23 100 ( 145 0) (160 0) ( 240 0)... Roughing 350 Semifinishing, finishing Roughing Semifinishing, finishing (0.0 04) 150 (500) 183 (600) 90 (300) 183 (600) 230 (750) 73 ( 240 ) 137 (45 0) 170 (560) 75 (250) 167 (550) 213 (700) 50 (160 ) 120 (40 0) 146 (48 0) 60 (200) 150 (500) 183 (600) (0.009) (0.012) 0.15 (0.006) 0.15 (0.006) 0.10 (0.0 04) 0.10 (0.0 04) 0.10 (0.0 04) 0.10 (0.0 04) 0.25 (0.010) 0.25 (0.010) 0.23 (0.009) 0.23 (0.009) 0.20 (0.008) 0.20 . 0.1 0- 0.36 0.00 4- 0.0 14 12 2- 213 40 0- 700 0.1 0- 0.38 0.00 4- 0.015 33 0 -4 50 C2 8 4- 137 27 5- 45 0 0.0 8- 0.25 0.00 3- 0.010 9 1-1 83 30 0- 600 0.0 8- 0.30 0.00 3- 0.012 Gray cast iron 45 0-7 00. 0.3 0- 0. 64 0.01 2- 0.025 9 1-1 22 30 0- 40 0 0.1 3- 0.51 0.00 5- 0.020 33 0 -4 50 C5 5 3-9 1 17 5- 300 0.2 5- 0.51 0.01 0- 0.020 7 6-1 06 25 0- 350 0.1 0- 0 .41 0.00 4- 0. 016 Alloy steels 45 0-7 00 C7 3 8-7 6. steel 18 0-2 40 C2 6 1-9 1 20 0- 300 0.0 8- 0.30 0.00 3- 0.012 6 8-1 22 22 5- 40 0 0.0 8- 0.38 0.00 3- 0.015 15 0-2 50 C2 1 8 -4 3 6 0- 140 0.1 3- 0.25 0.00 5- 0.010 2 3-6 1 7 5-2 00 0.0 8- 0.30 0.00 3- 0.012