Smithells Metals Reference Book Part 17 pptx

Steel heat treatment 2P-9 293.2 Hardening Rapid cooling from austenite. The rate of cooling and the composition control the structures obtained. In general steel specifications will give the recommended conditions. Guidance can be obtained from two types of diagram. This isothermal transformation diagrams (time/temperature/ trmsformation) show the degree of transformation through time for any temperature held from the austenite treatment. These are helpful for austempering treatments but for normal hardening, continuous cooling transformation temperature diagrams (CCT) are more useful. They give transformation conditions for particular compositions when cooled from austenite in air, oil or water. Transformation starts and finishes for pearlite, bainite and martensite are shown. M. Atkins, ‘An Atlas of Continuous Cooling Transformation Diagrams’, British Steel Corporation, Rotherham, UK should be consulted for this information. If quench to martensite is to be followed by tempering, temperature range 290-470 should be avoided since these can produce temper brittleness. For equipment parmeters in induction surface hardening see Table 29.5. 29.33 Casebardening A hard outer case is provided by diffusion of carbon or nitrogen or both into the surface. For the most complete treatment four processes are involved. (a) Diffusion of carbon into the surface between 880 and 930°C. This can be from a carbonaceous pack, from a gas or from a liquid salt, usually a cyanide. Nitrogen is usually diffused from a gas at about 500°C. For details ofcase depths and formulae in case hardening, see Table 29.6. (b) Core refining. Heat treatment to refine the grain size of the core by austenitizing and quenching-see Table 29.7. (c) Hardening. Heat treatment at a lower temperature that will austenitize the high carbon case followed by quench- Table 29.7. (d) Tempering. A low tempering treatment to give stress relief and reduce brittleness, usually below 200°C. For economy, a single quench is sometimes used. After carburizing, the temperature is allowed to fall to betweed that of (a) and (b) followed by quench. Steels for which this is acceptable are noted in Table 29.7. Steels suitable for nitriding are listed in Table 29.8. Surface hardening by flame or induction methods for various steels are listed in Table 29.9. For suitable induction equipment see Table 29.5. Hardness‘profiles of case and core for case carburizing steels of low, medium and high hardenability are given in Figure 29.3. 29.3.4 Surface treatments As well as carbon and nitrogen, surface diffusion treatments are available using aluminium, chromium, silicon boron and zinc. These processes with their properties and applications are listed in Table 29.10. Blueing of steel parts is included. 29.3.5 High carbon steel and alloy steels The same primary reactions apply to the heat treatment of high carbon steels as to the low carbon type, but the decarburizing reactions are of most importance. A variety of controlled atmospheres is available for industrial use and they are summarized below, the final choice being determined by the quality of product required and whether the heat treating temperature is above or below the Ac, point. Above 680-700°C the atmospheres for treatment are: 1. High temperature endothermic gas, produced from rich hydrocarbon gas/air mixtures, plus 2. Completely burnt hydrocarbon gas, processed over hot charcoal, plus hydrocarbon if 3. Chemically purified burnt hydrocarbon gas, dry and free from carbon dioxide, plus 4. Nitrogen or nitrogen plus hydrocarbon. 5. Vacuum. hydrocarbon addition if necessary. necessary. hydrocarbon if necessary. (texr continues on p29-16) Table 29.6 DIFFUSION PROCESSES FOR CASE-HARDENING Process class Process Description of process Process temperature Case depth Advantages Limitations Carburizing Pack Parts packed within a -925°C (carbon diffusion) heat-resistant box surrounded by a carburizing powder consisting of alkali carbonates, charcoal or coke tar, and molasses with a.barium carbonate energizer. 1.25 mm ( 5 h) 1.8 mm (10h) Low distortion. wasted. 2.5 mm (20h) Low capital cost. Simple. Labour intensive. Heat Liquid Parts suspended in molten salt Vary according to depth d=KP (h) Simple controls can be Poisonous salts and bath containing sodium cyanide required. Values of k automated. Bath heat re vapoun. Equipment (g23%), barium chloride, sodium 85OoC=k=0.0155 usable. Can combine maintenance necessary. chloride and accelerators. The salt bath can be heated externally with 900"C=k=0.021 heat treatment. oil gas, or electricity (submerged electrodes) d in inches 875°C = k= 0.018 925"C=k=0.025 carburizing, refining and Gas Good control. Suited to mass production. Can be combined with quenching. High capital cost-not suited to jobbing work. 31.6t1/' A special mufle furnace allows 925°C max. Higher d (in)=w carburizing gas mixture to pass temperatures shorten around the workpieces. The carbon furnace life and cause core source is usually a hydrocarbon, grain growth. often natural gas. t = time (h) T= absolute temperature (K\ Carbonitriding Cyaniding Gas Nitriding Liquid GaS Similar to liquid carburizing but 30-40% sodium cyanide. To provide nitrogen, bath must react with air. A freshly made bath is therefore aged for a few hours at 700°C before use. Proportions of carbon and nitrogen may be varied. Ammonia is used to provide nitrogen Low temperature cyanide bath, preaged to allow cyanate formation. With low temperatures and long times the case is mostly nitride. Fully machined and heat-treated parts are nitrided in a mume in contact with ammonia gas. 870°C Thinner cases than liquid carbunzing. Lower than with gas carburizing. Lower carburizing. temperatures increase nitrogen percentage. 550°C Thin Thinner cases than gas 500-565°C Thinner but harder and more temper-resistant case than liquid carburizing. Hard wear resistant case. Longer equipment life. Hard and temper resistant case. Hard and wear-resistant. Improved fatigue properties. Machined and hardened before casing. No distortion or grinding necessary. Similar to liquid nitriding: used for crankshafts. camshafts, gear shift forks, etc. Poisonous salts. Similar to gas carburizing. Thin case. Slow process. Not suitable for heavy coarse work. Case brittle and can crack or spall, if used with plain carbon steels, hence special steels necessary. c. N Table 29.7 CARBURIZING STEELS-LOW HARDENABILITY (see footnotes) Tensile Impact Refine Harden strength Elongation toughness Steel designation BS970 En. no. C Mn Other "C "C MPa % J Remarks Carbon 045M10 32A 0.1 0.5 870-900 (1) 760-780 (W) 500 20 55 Properties sensitive to section size 080M15 32C 0.15 0.75 870-900(1) 760-780CjV) 500 20 55 As above 210M15 32M 0.15 1.0 0.1-0.18 S 870-900 (1) 760-780 (W) 500 20 55 Free-cutting Carbon- 130M15 201 0.15 1.3 870-900 (1) 770-790 (W) 620 20 55 Hardenability improves core manganese strength Lowchromium - 214M15 202 0.15 1.5 0.1-0.18 S 870-900 (1) 770-790 (W) 600 20 40 Free-cutting (as above) 207 0.17 0.7 0.6-0.8 Cr - - 600-800 - 55 Water quench for higher strength MEDIUM HARDENABILITY Steel designation BS970 En. no. C Mn Other Tensile Impact Ref? Harden strength Elongation toughness "C "C MPa % J Remarks ~ 33 0.12 0.5 3 Ni 3% nickel - 850-880 (1) 760-780 (0) 700 18 55 Good shock resistance 18 55 Good shock resistance 2% nickel-Mo 665M17 34 0.17 0.5 2Ni0.25 Mo 850-880 (1) 760-780 (0) 700 Moderate shock resistance 2% nickel-Mo 665M33 35 0.23 0.5 1.7 Ni 0.25 Mo 850-880 (1) 760-780 (0) 850 15 30 (higher C) ‘20’ carbon low 805M20 362 0.20 0.8 0.5 Ni 0.5 Cr 0.2 Mo 850-880 (1)* 780-820 (O)* 850 15 20 LOT shock mistance alloy Low nickel-Cr- - 325 0.22 0.5 1.7 Ni 0.5 00.25 Mo 850-880 (I )* 770-800 (O)* 850 15 40 Tough, medium strength Mo f nickel-Cr 635MlS 351 0.15 0.8 0.75 Ni 0.5 Cr 850-880 (I)* 780-820 (O)* 700 18 40 Good shock resistance ‘15’ carbon low 80511117 361 0.17 0.8 0.5 Ni 0.5 Cr 0.2 Mo 850-880 (1)* 780-820 (O)* 700 18 35 Moderate shock resistance alloy 1% nickel-Cr 63511117 352 0.17 0.8 1.0 Ni 0.75 Cr 850-880 (1)* 780-820 (O)* 850 15 27 Moderate shock resistance HIGH HARDEN ABILITY Steel designation 3 nickel-Cr 5 nickel 4 nickel-Cr (Mo) 14 nickel-Cr If nickel-Cr- Mo 2% nickel-Cr BS 970 655M13 828M13 - 835M15 815M17 82011117 822M17 En. no. 36A 36C 37 39B 353 354 355 C Mn 0.15 0.5 0.15 0.5 0.16 0.45 0.15 0.4 0.17 0.75 0.17 0.75 0.17 0.5 Other 3.5 Ni 0.75 Cr 3.5 Ni 0.75 Cr 5 Ni 0.15 Mo 4.0 Ni 1.2 Cr 0.2 Mo 1.25 Ni 1.0 Cr 1.75 Ni 1.0 Cr 0.1 Mo 2 Ni 1.5 Cr 0.2 Mo Refine “C 850-880 (1) 850-880 (1) 850-880 (1) 850-880 (2) 850-880 (2) 850-880 (a)* 850-880 (2)* Harden “C 760-780 (0) 760-780 (0) 750-780 (0) 760-780 (O)? 780-820 (0) 780-830 (O)* 780-820 (O)* Tensile strengrh MPa Elongation % Impact roughness J Remarks 850 1000 620 1310 lo00 1150 1310 1s 13 20 12 12 12 12 47 40 68 34 27 27 34 Good shock resistance As above Max toughness Heavy duty components Moderate shock resistance As above Heavy duty gears. etc. ~~___ ~~ ~~ *Or single quench 810-830 (0). t Temper 200°C max. Carburize at 880-930°C. (l)=A/O/W. (2)=W/O. A=air cool. O=oil quench. W=water quench. 8 f a m P Table 29.8 STEELS SUITABLE FOR NITRIDING c; P Steel designation Composition % Typical mechanical properties Section Yield Tensile Impact size strength strength toughness En. no. C Si Mn Ni Cr Mo V AI mm MPa MPa J Remarks 3% chromium- 40A 0.1 0.1 0.4 0.4 2.9 0.4 - - 150 750 950 50 3% chromium- 4OC 0.3 0.1 0.6 0.4 0.2 0.1 0.1 - 60 1100 1300 20 Higher strength. High molybdenum-vanadium 0.35 max 1.3 temperature strength. Higher hardenability. If chromium- 41A 0.25 0.1 0.65 0.4 1.4 0.10 - 0.9 60 850 lo00 45 High hardenability. aluminium-molybdenum 0.45 0.45 max max 1.8 0.25 1.3 150 550 850 50 Higher case hardness. 418 High wear resistance. Corrosion resistance. 0.25-0.35% C gives core strength of 700-850 MPa. 0.35-0.45% C gives core strength of 850-1 000 MPa. molybdenum 0.3 0.35 0.65 max 3.5 0.7 s Nitralloy N - 0.2 0.2 0.4 3.25 1.00 0.20 - 0.85 - I 200 1 300 - High strength. 5% Ni-2% AI - 0.20 0.2 0.25 4.75 0.40 0.20 0.09 1.80 - 1350 1 400 20 Very high core strength. 0.27 0.4 0.7 3.75 1.50 0.30 1.20 0.25 0.3 0.45 5.25 0.80 0.30 0.15 2.20 Table m.9 SURFACE HARDENING BY FLAME OR INDUCTION TREATMENTS Free cutting Alloy ~~ ~ Basic steel composition Rockwell hardness (HRc) Steel Air (a) Oil (b) Water (b) type C Mn 0 Ni Mo S quench quench quench - Plain carbon 0.25-0.35 0.6 - - - - - - 35-50 0.6-0.8 - - - - - 52-58 55-60 0.55-0.75 0.6-0.8 - - - - 50-60 58-62 60-63 0.83-0.96 0.5-0.6 - - - - 55-62 58-62 62-65 0.25-0.37 1.3-1.6 - - - 0.08-0.13 - - 45-55 45-55 52-57 55-62 0.38-0.44 1.3-1.6 0.46-0.51 0.7-1.8 - - - 0.08-0.2 50-55 55-60 58-64 0.38-0.48 1.6-1.9 - - - - 45-55 52-57 55-62 0.4 -0.52 - 0.08-0.13 - - 0.36-0.44 0.6-0.9 0.5-0.8 1.1-1.5 - - 50-60 55-60 60-64 0.28-0.38 0.7-0.9 0.3-1.1 - 0.15-0.25 - - 50-55 55-60 0.38-0.43 0.2-0.35 0.8-1.1 - 0.15-0.25 - 52-56 52-56 55-60 0.48-0.53 0.7-1.0 0.8-1.1 - 0.15-0.25 - 58-62 58-62 62-65 0.38-0.43 0.6-0.8 0.7-0.9 1.6-2.0 0.2 -0.3 - 55-51 33-57 60-63 0.28-0.33 0.7-0.9 0.4-0.6 0.4-0.7 0.15-0.25 - 48-33 52-57 58-62 0.4 -0.64 0.7-1.0 0.4-0.6 0.4-0.7 0.15-0.25 - 55-63 55-63 62-64 (a) Pam away from heated surfaos must be kept cool. @)Thin sections are susceptible to cracking when oil or water quenched. 29-16 Heat treatment Table 29.10 DIFFUSION AND OTHER SURFACE TRFATMENTS OF STEEL Process Properties Applications Aluminizing (calorizing) also for nickel and cobalt alloys. Aluminium or ferro-aluminium powder, volatile halide and ceramic heated to 815-1 200°C for 6-24 h. Chromizing. Chromium powder, halide and inert aggregate heated 800-1 300°C for about 20 h in presence of hydrogen. Siliconking. A pack of silin carbide or fmosilicon and circulating gas at 900-1 0oO"C. Silicon chloride is carrier gas. Sheradizing. Diffusion of zinc to form a coating. Zn dust and sand packed around parts and heated to 300400°C for 3-10 h. Zn vapour acts as carrier-see BS 4291. Bor~nizing'~. Diffusion of boron into plain carbon steel. Treatment temperature 800-1 0oO"C. Blueing. Used on low carbon steel. Au/steam 450-600"C. Steam must not be admitted below 350°C. Coating is about 60% AI at surface and about 150 pm. With post diffusion heat-treatment AI at surface decreases to t25% Al with deerease of thickness to < 125 pm. Coating is resistant to combustion and S gases. Surface > 12% Cr and ferritic. up to loo pm thickness is possible. Better oxidation resistance at higher temperatures than stainless steel. Coating 300-750 pm. 14% Si at surface. 12% Si in bulk. Combination of corrosion and wear resistance and some oxidation resistance. Case is brittle. Matt grey. Corrosion resistance proportional to thickness. Coating about 8-9% Fe. Can be painted without pretreatment. Very uniform. Very hard case. Vickers hardness lMOH,,. Case thickness 0.05 mm (50-80 pm). A blue mainly decorative surface is obtained. High tempture corrosion resistance. Chemical and petroleum processes. Engine Parts. High temperature oxidation resistance. Pump shafts, cylinder liners, valves and valve guides. Fittings. Small psings, forgings, castings, nuts, bolts, washers. Lengths of rod or tube. Hard surface applications. Nuts, bolts, etc. Below 680-700°C the atmospheres for treatment are: 1. Dry burnt hydrocarbon gas. 2. Dry burnt ammonia. 3. Cracked ammonia. 4. Nitrogen. Processes have been developed for bright hardening in which the steel is quenched in a blast of non-oxidizing controlled atmospheres, which, if necessary, is refrigerated. ALLOY STEELS The nature and concentrations of the alloying elements deterrmn e the type of controlled atmosphere which will ensure freedom from oxidation or decarburization during heat treatment. Austenitic and martensitic stainless steels, etc. If the alloying elements form oxides of low dissociation pressure, and are present in concentrations exceeding about 1%, the controlled atmosphere must be quite free from oxygen-bearing gases, and the choice is limited to cracked ammonia, dry hydrogen, or dry nitrogen/hydrogen mixtures. Straight nickel steels These can be bright heat treated successfully in atmospheres suitable for their plain carbon steels equivalents, except that the use. of a desulphurized atmosphere is advisable. For this reason all alloy steels should be degreased before treatment if surface staining is to be avoided. Aluminium alloys 29-17 Martensitic types of stainless steel Such types are treated in cracked ammonia having a controlled addition of methane or propane to prevent decarburization, and quenched in the controlled atmosphere5 or oil. High speedsteels These are preferably treatment in salt bath furnaces, but where the nature and size of the work does not permit this a controlled atmosphere can be used6. The formation of an oxide skin is not objectionable, since the tools are normally surface-ground before use, and such a skin may in fact give added protection against decarburization. TOOL STEELS AND CAST STEELS For heat treatments of tool steels see Table 22.50. For forged and rolled steels see Table 22.44. The conditions of heat treatment for these complex steels must be obtained from individual specifications. 29.4 Cast iron treatments 29.4.1 Mnlleablizing Whiteheart malleablizing-xiow little used-is produced by a simultaneous graphitizing and decarburizing treatment of white cast iron. The decarburizing atmosphere can be produced by a suitable atmosphere or by reaction between the air in the furnace and the carbon in the coatings. The resulting atmosphere, rich in carbon dioxide, is circulated and the carbon monoxide converted to dioxide by addition of air of steam. Batch or continuous furnaces operate at 1050°C. For Blackheart malleablizing, decarburization is prevented by a completely neutral atmosphere such as dry nitrogen or completely burned hydrocarbon gas stripped of carbon dioxide to 0.1% and water vapour to a dew point of -40°C. Alternatively fully burned ammonia can be used-see Chapter 26-80. The carbide in the white iron changes to areas of temper carbon. The process is carried out at 1050°C (first stage) and 750450°C (second stage). 29d.2 Nodular cast iron or spheroidal graphite iron (SG) The nodules of graphite are in a steel-like matrix that can be heat treated in ways similar to steel thus giving a great versatility of end products. An important development is the amtempering treatment of nodular cast irons. The nodular casting-(for production see 26.9)-is first austenitized and then quenched into a temperature of between 250 and 450°C where it is held so that transformation occuls from austenite to bainite. It is then air cooled to ambient temperature. Additions of copper, nickel and molybdenum can be used to facilitate and improve the 295 Aluminium alloys 29.5.1 Anding For softening aluminium alloys that have been hardened by cold work: Alloys 1080A, 1050, 1200,5251, 5154A, 5454,5083-360°C for 20min. Alloys 3103,3105-lO0-425"C for 20 min. Heat-treatable alloys that have not been heat treated-360°C & 10°C for 1 h and cool in air. Alloys that have been heat treated 400-425"C for 1 h and cool at 15"C/h to 300°C. For AI-Zn-Mg alloys of the 7000 series, after cooling in air, reheat to 225°C for 2-4 h. 2951 stai)ilizing To relieve internal stress. Normally heat to 250°C followed by slow cooling is adequate. [...]... Mg Water - Hot water Air blast 495-505 AI Si23 Cu Mg Ni Hot water - - - 495-505 Air blast - Al Si17 Cu4 Mg 150 -170 150 -170 150 -170 - 160-180 160-180 200-250 - 160 -179 - 6-18 16 16 - 4-16? 4-16 4-16 - 8-10 - 250 155 -175 155 -175 200-210 185 185 185 185 175 -225 2-4 8-12 8-12 7-9 95-110 or room temperature 150 -175 150-180 or 195-205 2 t 8 t 8 8 JE '' series L 4L 35 Al Cu4 Ni2 Mg2 3L 51 3L 52 A Si2 Cu Ni... Al Cu4 Mgl 2031 2 117 2618A 6061 A1 Mg Si Water Water Water Water Water Water Water Water Water Water or oil Water Water Water Water Water 525f 5 530 f 10 530 f 10 525f15 525 f 5 525 f 5 525 f 5 525f5 475 10 475 f 10 Al Cu2 Nil Mg Fe Si Al Cu2 Mg Al Cu2 M l 5 Fel Nil g Al Mgl Si Cu 6063 Water Water Water Water Water Water Water Water Water Water 172 +3* or 120k3 followed hy 172 53 Water 172 f3* Water 85°Cor... base alloys reference should be made t Copper Development Association data sheets o Magnesium alloys 2!4-21 Table 29.14 ANNEALING A N D STRESS RELIEVING OF COPPERS AND BRASSFST IS0 alloy designation Annealing range ("C) Stress reIhing range ("C) Cu Cd3 and Cu Cd Sn Cu Si3 Mnl 200-650* 225-650* 200-650 225-600 250-650 375-650 350-650* 400-650 425-650* 500-700 475-700 150-200 175 -225* 170 -200 175 -225 200-250... Inconel 617 Inconel 706 Stress relief N10003 - NlMK)4 No6002 - No6600 NO6601 NO6625 - 1175 1175 1095 1010 980 980 1 1 2 0.25 f f f 900 f f f 1 I 1 870 1 f Inconel 718 NO7718 955 1 InconelX750 AMS 5667 AMS 5668 Nimonic8OA Nimonic 90 Rene 41 Unimet 500 Unimet 700 NO7750 1035 0.5 880 NO7080 No7090 NO7041 NO7500 - 1080 1080 1080 1080 1135 2 2 2 4 4 f f f f f NO7001 1010 4 f Waspalloy Solution treatment 1175 ... No7090 NO7041 NO7500 - 1080 1080 1080 1080 1135 2 2 2 4 4 f f f f f NO7001 1010 4 f Waspalloy Solution treatment 1175 lo65 1220 1175 1175 1095 1120 1150 1150 1175 925-1010 0.5 WQ 0.5 WQ 1SQ 1SQ 1SQ 2WQ 2AC 1AC ZSQ 2SQ f f f f f 1AC 855 1150 f 980 24AC 2AC 1080 1080 1065 1080 1175 1080 1080 SAC 8AC 0.5AC 4AC 4AC 4AC 4AC Ageing AS AS - 790 2AC 845 720 620 720 620 705 845 3AC 8FC SAC 8FC 8AC MAC 24AC 705... AS 1175 1175 1175 1230 0.5RAC 0.5RAC 1SQ 1AC - Temp Alloy UNS Temp CC) (hs) Temp.(T) Time&) ec, Hayes25 L-605 Hayes 188 Hayes566 S816 Stellite 6B R30605 1230 1 f R30188 - R30816 - 1205 1 f Time Ageing 760 - Time (h) 12 AC Notes: RAC=rapid air cool, AC=& cool, h=hours, hs=hours/inch of d o n , AS=ageing during Service, f=wfull anneal, @=quench b l W C rapidly enough t prevent precipitation am o REFERENCES... Industrial Laser Annual Handbook‘, eds D Belforte and M.Levitt, F’ennwell Books Laser beam principles 10 I J Spalding, ‘Characteristics of Laser Beams for Machining’, in ‘Physical Processes in Laser Materials Interactions’, ed M Bertolotti, Plenum, 1983 11 J T Luxon, ‘Optics for Materials Processing’, in the 1986 ‘Industrial Laser Annual Handbook’, eds D Belforte and M Levitt, Pennwell Books, 1986, pp38-48... treated, artificially aged and stabilized Thermally stress relieved TS Room 155-165 Room Room 155-190 155-190 Room Room Room 155-205 Room 160-200 Room 165- 195 Room 160-180 160-180 Room 175 -185 165-195 Room 170 f 10 Room 170 f 10 510f5 510f5 50555 505 f 5 505 f 5 505f5 495 f 5 495 f 5 495 5 5 525 f 10 495 f 5 530 k5 525 f 15 525 f 15 5255 5 48 12 48 48 5-20 5-20 48 48 48 2-20 96 16-24 - 3-12 - 5-15 5-15... Water Water 172 +3* or 120k3 followed hy 172 53 Water 172 f3* Water 85°Cor oil 135f5 Water or oil 135f 5 Water 135f 5 Water 135f5 Water (6040°C) 110k5 or 12055 followed by 177 f5 Water 11055 177 f 5 followed by Water 70°C 110f5 12055 OI 177 55 followed by - 6082 Al Si1 Mg Mn 6101A A1 Mg Si 6463 AlMgsi 7010 Al Zn6 Mg2 Cu2 7014 * 465+10 460k 10 46Of 10 46Of10 460f 10 465 5 A1 2115.5 Mg2 Cu Mn 7075 Al Zn6 Mg... MAG 7 A17.519.5 Zn0.3/1.5 Mn0.15 MEL MAG 7 (ST&PT) A17.5/9.5 Zn0.3/1.5 Mn0.15 *In hydrogen.Max 490°C + - - 8 AC 16 AC 200 10 AC 380-390 410-420 8 AC 16 AC - - 380-390 410-420 8 AC 16 AC 200 10 AC Nickel and cobalt alloys 29-23 Table 29.16 HEAT TRF$ATMENTOF MAGNESIUM WROUGHT ALLOYS Specifications Composition Form Solution treatment Temperature CC) Time (h) FCh Temperature CC) Time@) quench Ex - - 177 16 . 160-180 Room 175 -185 Room 170 f 10 Room 170 f 10 172 +3* 120k3 172 53 172 f3* 135f5 135 f 5 135 f 5 135f5 110k5 12055 177 f5 11055 177 f 5 110f5 12055 177 55 165-195 -. (50-70°C) 150 -170 150 -170 150 -170 - 160-180 160-180 200-250 160 -179 250 155 -175 155 -175 200-210 185 185 185 185 - - 175 -225 95-110 or room temperature 150 -175 150-180 or. 828M13 - 835M15 815M17 82011 117 822M17 En. no. 36A 36C 37 39B 353 354 355 C Mn 0.15 0.5 0.15 0.5 0.16 0.45 0.15 0.4 0 .17 0.75 0 .17 0.75 0 .17 0.5 Other 3.5 Ni 0.75