20CrMoH齿轮用钢热处理工艺研究
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摘要
本文研究了20CrMoH 汽车齿轮用渗碳钢的预先热处理等温正火工艺对组织和性能的影响,还研究了不同渗碳热处理工艺参数对渗碳层显微组织的影响。通过拉伸、冲击和台架试验等性能分析试验,最终确定了20CrMoH 齿轮钢热处理渗碳淬火最佳工艺参数。
20CrMoH 汽车齿轮用渗碳钢采用普通正火,由于钢件内外冷却速度不一样且连续冷却转变是在相当大的过冷范围内完成的,因而所获得的显微组织和硬度难以达到技术标准要求;采用等温正火可以获得良好的显微组织和硬度,以利于切削加工性能。同时有效减小热处理淬火变形。
研究了20CrMoH 汽车齿轮用钢在连续渗碳生产线不同区域渗碳过程的碳势、渗碳温度、淬火温度等工艺参数对有效硬化层、显微组织、表面硬度、心部硬度以及碳浓度分布和渗碳层硬度分布的影响规律。确定了最佳的热处理渗碳工艺参数为:Ⅰ区880℃;Ⅱ区900℃、碳势为1.00 %;Ⅲ区920℃、碳势为1.15%;Ⅳ区900℃、碳势为0.90 %;Ⅴ区835℃、碳势为0.90%;回火温度190℃,推料周期为25 分钟。对按此最佳热处理工艺参数生产的20CrMoH 齿轮装配CA7-100 变速箱总成后进行了台架寿命试验,验证了此最佳工艺的可行性。此工艺应用于汽车生产中取得了极为可观的经济效益。
In the present study, the effect of pre-heat treatment of isothermal normalizing on the structure and performance of 20CrMoH gear steel were studied, and the effects of the parameters of different carburizing on the microstructure in carburized layers of the steel were also investigated. According to the results of tension, impact and bench tests, the optimal carburizing-quenching parameters of the 20CrMoH gear steel were determined.
For using the normal normalizing, because the continues cooling transformation takes place within a wide range of temperature and also because of the different cooling rate in different parts of the steel pieces, it is difficult for the obtained microstructure and hardness to fit for the engineering standard. However, when using isothermal normalizing, the optimal microstructure and hardness can be obtained, which also reduces quenching deformation.
The effect of processing parameters such as carbon potential, carbonizing temperature, quenching temperature on the rules of effective harden layer, microstructure, interior rigidity, distribution of hardness and carbon concentration were studied. Based on the above analysis, the optimal parameters of carburizing processing are determined as follows: the temperature in the zones of I, II, III, IV, and V is 880℃, 900℃, 920℃, 900℃and 835℃, respectively. The carbon potential in zones of II, III, IV and V is 1.00%, 1.15%, 0.90% and 0.90%, respectively. The temping temperature is 190 ℃, and the cycle of feed is 25min. The bench tests was carried out in the CA7-100 gearbox assembled with 20CrMoH gear steel treated at the optimization condition parameters, which proofs the technique proposed in the study to be excellent. The optimization technique has been adopted in automotive truck, and a great benefit is gained.
20CrMoH 汽车齿轮用渗碳钢采用普通正火,由于钢件内外冷却速度不一样且连续冷却转变是在相当大的过冷范围内完成的,因而所获得的显微组织和硬度难以达到技术标准要求;采用等温正火可以获得良好的显微组织和硬度,以利于切削加工性能。同时有效减小热处理淬火变形。
研究了20CrMoH 汽车齿轮用钢在连续渗碳生产线不同区域渗碳过程的碳势、渗碳温度、淬火温度等工艺参数对有效硬化层、显微组织、表面硬度、心部硬度以及碳浓度分布和渗碳层硬度分布的影响规律。确定了最佳的热处理渗碳工艺参数为:Ⅰ区880℃;Ⅱ区900℃、碳势为1.00 %;Ⅲ区920℃、碳势为1.15%;Ⅳ区900℃、碳势为0.90 %;Ⅴ区835℃、碳势为0.90%;回火温度190℃,推料周期为25 分钟。对按此最佳热处理工艺参数生产的20CrMoH 齿轮装配CA7-100 变速箱总成后进行了台架寿命试验,验证了此最佳工艺的可行性。此工艺应用于汽车生产中取得了极为可观的经济效益。
In the present study, the effect of pre-heat treatment of isothermal normalizing on the structure and performance of 20CrMoH gear steel were studied, and the effects of the parameters of different carburizing on the microstructure in carburized layers of the steel were also investigated. According to the results of tension, impact and bench tests, the optimal carburizing-quenching parameters of the 20CrMoH gear steel were determined.
For using the normal normalizing, because the continues cooling transformation takes place within a wide range of temperature and also because of the different cooling rate in different parts of the steel pieces, it is difficult for the obtained microstructure and hardness to fit for the engineering standard. However, when using isothermal normalizing, the optimal microstructure and hardness can be obtained, which also reduces quenching deformation.
The effect of processing parameters such as carbon potential, carbonizing temperature, quenching temperature on the rules of effective harden layer, microstructure, interior rigidity, distribution of hardness and carbon concentration were studied. Based on the above analysis, the optimal parameters of carburizing processing are determined as follows: the temperature in the zones of I, II, III, IV, and V is 880℃, 900℃, 920℃, 900℃and 835℃, respectively. The carbon potential in zones of II, III, IV and V is 1.00%, 1.15%, 0.90% and 0.90%, respectively. The temping temperature is 190 ℃, and the cycle of feed is 25min. The bench tests was carried out in the CA7-100 gearbox assembled with 20CrMoH gear steel treated at the optimization condition parameters, which proofs the technique proposed in the study to be excellent. The optimization technique has been adopted in automotive truck, and a great benefit is gained.
引文
1 张学孟.汽车手动换挡变速器的发展.齿轮技术信息,1996,(1):1~12
2 朱法义等.20Cr2Ni4A 钢制齿轮稀土低温高浓度渗碳后弯曲疲劳强度的研究.材料科学与工艺,1994,2(3):61~65
3 S. E.Yu. Study on Improving Rolling Contact Fatigue Strength for Carburizing Gears with Retained Austenite and Carbide in Their Case and Its Application. Trans. Met. Heat Treat, 1989,10 (1):31~43
4 汤宏智等.汽车齿轮硬化层深的设计.汽车工艺与材料,1998,(3):6~10
5 刘云旭等.重行奥氏体化淬火提高渗碳钢件力学性能的研究.汽车工艺与材料,1998,(1):8~11
6 胡建文等.渗碳齿轮有效硬化层的碳浓度研究.热加工工艺,1999,11(4):19~20
7 M. F. Yan,Z.R.Liu. Study on Microstructure and Micro Hardness in Surface Layer of Steel 20CrMnTi Carburized at 880oC with and Without RE, Mater.Chem.Phys.,2001,72(2):97~100
8 Y. F. Cai. Analysis and Prevention of Longitudinal Cracks Occurring in Bevel Drive Gear of Rear Axle after Heat Treatment. Heat Treat.Met.,1991,(9):20~29
9 杨其苹等.汽车齿轮钢的现状及发展.汽车工艺与材料,1997,(6):1~4
10 G. F. Long. Controlling the Quenching Distortion of Gears. Heat Treat.Met., 1994,(5):39~40
11 M. F. Yan, C. H. Cai, Z. R. Liu. Study on the Replacement of Conventionally Complex Processing for Steel 20Cr2Ni4A by RE Crburizing at Lower Temperature, Mater.Sci.Tech.,2001,17(8):1021~1024
12 穆静等.渗碳钢的淬透性与热处理畸变.金属热处理,2001,(3):33~34
13 M. Benedetti. Influence of Shot Peening on Bending Tooth Fatigue Limit of Case Hardened Gears. International Journal of Fatigue,2002,24(50):1127~ 1136
14 J. L. Pacheco, G. Krauss. Microstructure and High Bending Fatigue Strength in Carburized Steel. J.Heat Treat,1989,124(7):77~79
15 D. M. Dudley. Gear Handbook. New York: Mc Graw Hill Co,1962:10~18
16 杨其苹等.易切削渗碳齿轮钢.汽车工艺与材料,1998,(5):22~25
17 曹正等.汽车齿轮用合金钢技术标准.长春汽车材料研究所,2000:5~7
18 张洪远.国产8620H 钢及其在富勒变速箱生产中的应用.汽车齿轮,1993,(3):15~18
19 M. F. Yan. Study on Absorption and Transport of Cabon in Steel during Gas Carburizing with Rare Earth Addition. Mater.Chem.Phys.,2001,70(2):242~ 245
20 谭崇凯.国产ZF 钢工艺试验.綦齿传动,1997,(2):23~28
21 刘世骧.锻件余热等温退火节能新工艺.机械研究与应用,1995(2):38~40
22 刘云旭.合金渗碳钢件预先热处理的研究.汽车工艺与材料,1997,(8):12~15
23 雷天同等.20CrMnTi 齿轮锻后余热正火的工艺试验及应用.辽宁工学院学报,1994,14(3):6~10
24 P. Rangaswamy. Experimental Measurements and Numerical Simulation of Stress and Microstructure in Carburization 5120 Steel Disks.Mater.Sci. Eng., 2001,298(7):158~165
25 M. F. Yan, W. Pan, T. Bell, Z. R. Liu. The Effect of Rare Earth Catalyst on Carburizing Kinetics in a Sealed Quench Furnace with Endothermic Atmos-phere. Appl.Surf.Sci., 2001,173(1):91~94
26 T. Bell, Y. Sun, Z. R. Liu, M. F. Yan. Rare Earth Surface Engineering.Heat Treat.Met, 2000,27(1):1~8
27 陶晋等.20CrMnMoA 渗碳淬火齿轮弯曲疲劳强度的试验研究.机械设计,2001,(4):23~24
28 D. M. Dudley. Gear Handbook. New York: Mc Graw Hill Co, 1962:28~39
29 刘云旭等.汽车齿轮用渗碳钢的发展现状及前景.汽车工艺与材料,1998,(9):1~4
30 赵麦群等.深层渗碳碳化物形态对弯曲疲劳性能的影响规律.热加工工艺,1996,(3):13~15
31 祝海泉.合理制订渗碳淬火工艺的计算方法.热处理,2002,17(3):26~32
32 燕来生.提高渗碳钢多冲接触疲劳抗力的研究.金属热处理学报,2000,21(4):52~56
33 张秀全等.齿轮淬火变形分析与控制.煤矿机械,1999,(2):20~21
34 陈云生等.箱式炉变速箱齿轮渗碳的工艺控制.汽车行业技术交流资料,1997,(5):35~37
35 孙和庆等.大型重载齿轮深层渗碳的工艺控制.金属热处理,1994,(1):25~28
36 H. P. Cui. Carburization and Heat Treatment for Heavy Load Gears. Heat Treat.Met.,1992,(5):42~43
37 M. F. Yan, W. Pan, T. Bell. Catalysis of Rare Earths on the Kinetics Process of Carburizing in a Sealed Quench Furnace with Endothermic Atmosphere, Appl.Surf.Sci.,2001,173(2):91~94
38 S. Dorn, F. T. Hoffmann, P. Mayr. Proceedings of the Second International Conference on Carburizing and Nitriding with Atmosphere International Conference,1995,(6):89~96
39 樊东黎等.钢的过冷奥氏体等温转变曲线.热处理工程师手册,1999,(6):136~138
40 刘彦戌等.汽车标准汇编.中国汽车技术研究中心标准化研究所,2000,1(2):30~31
2 朱法义等.20Cr2Ni4A 钢制齿轮稀土低温高浓度渗碳后弯曲疲劳强度的研究.材料科学与工艺,1994,2(3):61~65
3 S. E.Yu. Study on Improving Rolling Contact Fatigue Strength for Carburizing Gears with Retained Austenite and Carbide in Their Case and Its Application. Trans. Met. Heat Treat, 1989,10 (1):31~43
4 汤宏智等.汽车齿轮硬化层深的设计.汽车工艺与材料,1998,(3):6~10
5 刘云旭等.重行奥氏体化淬火提高渗碳钢件力学性能的研究.汽车工艺与材料,1998,(1):8~11
6 胡建文等.渗碳齿轮有效硬化层的碳浓度研究.热加工工艺,1999,11(4):19~20
7 M. F. Yan,Z.R.Liu. Study on Microstructure and Micro Hardness in Surface Layer of Steel 20CrMnTi Carburized at 880oC with and Without RE, Mater.Chem.Phys.,2001,72(2):97~100
8 Y. F. Cai. Analysis and Prevention of Longitudinal Cracks Occurring in Bevel Drive Gear of Rear Axle after Heat Treatment. Heat Treat.Met.,1991,(9):20~29
9 杨其苹等.汽车齿轮钢的现状及发展.汽车工艺与材料,1997,(6):1~4
10 G. F. Long. Controlling the Quenching Distortion of Gears. Heat Treat.Met., 1994,(5):39~40
11 M. F. Yan, C. H. Cai, Z. R. Liu. Study on the Replacement of Conventionally Complex Processing for Steel 20Cr2Ni4A by RE Crburizing at Lower Temperature, Mater.Sci.Tech.,2001,17(8):1021~1024
12 穆静等.渗碳钢的淬透性与热处理畸变.金属热处理,2001,(3):33~34
13 M. Benedetti. Influence of Shot Peening on Bending Tooth Fatigue Limit of Case Hardened Gears. International Journal of Fatigue,2002,24(50):1127~ 1136
14 J. L. Pacheco, G. Krauss. Microstructure and High Bending Fatigue Strength in Carburized Steel. J.Heat Treat,1989,124(7):77~79
15 D. M. Dudley. Gear Handbook. New York: Mc Graw Hill Co,1962:10~18
16 杨其苹等.易切削渗碳齿轮钢.汽车工艺与材料,1998,(5):22~25
17 曹正等.汽车齿轮用合金钢技术标准.长春汽车材料研究所,2000:5~7
18 张洪远.国产8620H 钢及其在富勒变速箱生产中的应用.汽车齿轮,1993,(3):15~18
19 M. F. Yan. Study on Absorption and Transport of Cabon in Steel during Gas Carburizing with Rare Earth Addition. Mater.Chem.Phys.,2001,70(2):242~ 245
20 谭崇凯.国产ZF 钢工艺试验.綦齿传动,1997,(2):23~28
21 刘世骧.锻件余热等温退火节能新工艺.机械研究与应用,1995(2):38~40
22 刘云旭.合金渗碳钢件预先热处理的研究.汽车工艺与材料,1997,(8):12~15
23 雷天同等.20CrMnTi 齿轮锻后余热正火的工艺试验及应用.辽宁工学院学报,1994,14(3):6~10
24 P. Rangaswamy. Experimental Measurements and Numerical Simulation of Stress and Microstructure in Carburization 5120 Steel Disks.Mater.Sci. Eng., 2001,298(7):158~165
25 M. F. Yan, W. Pan, T. Bell, Z. R. Liu. The Effect of Rare Earth Catalyst on Carburizing Kinetics in a Sealed Quench Furnace with Endothermic Atmos-phere. Appl.Surf.Sci., 2001,173(1):91~94
26 T. Bell, Y. Sun, Z. R. Liu, M. F. Yan. Rare Earth Surface Engineering.Heat Treat.Met, 2000,27(1):1~8
27 陶晋等.20CrMnMoA 渗碳淬火齿轮弯曲疲劳强度的试验研究.机械设计,2001,(4):23~24
28 D. M. Dudley. Gear Handbook. New York: Mc Graw Hill Co, 1962:28~39
29 刘云旭等.汽车齿轮用渗碳钢的发展现状及前景.汽车工艺与材料,1998,(9):1~4
30 赵麦群等.深层渗碳碳化物形态对弯曲疲劳性能的影响规律.热加工工艺,1996,(3):13~15
31 祝海泉.合理制订渗碳淬火工艺的计算方法.热处理,2002,17(3):26~32
32 燕来生.提高渗碳钢多冲接触疲劳抗力的研究.金属热处理学报,2000,21(4):52~56
33 张秀全等.齿轮淬火变形分析与控制.煤矿机械,1999,(2):20~21
34 陈云生等.箱式炉变速箱齿轮渗碳的工艺控制.汽车行业技术交流资料,1997,(5):35~37
35 孙和庆等.大型重载齿轮深层渗碳的工艺控制.金属热处理,1994,(1):25~28
36 H. P. Cui. Carburization and Heat Treatment for Heavy Load Gears. Heat Treat.Met.,1992,(5):42~43
37 M. F. Yan, W. Pan, T. Bell. Catalysis of Rare Earths on the Kinetics Process of Carburizing in a Sealed Quench Furnace with Endothermic Atmosphere, Appl.Surf.Sci.,2001,173(2):91~94
38 S. Dorn, F. T. Hoffmann, P. Mayr. Proceedings of the Second International Conference on Carburizing and Nitriding with Atmosphere International Conference,1995,(6):89~96
39 樊东黎等.钢的过冷奥氏体等温转变曲线.热处理工程师手册,1999,(6):136~138
40 刘彦戌等.汽车标准汇编.中国汽车技术研究中心标准化研究所,2000,1(2):30~31