38CrMoAlA钢制齿轮的气体渗氮工艺
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摘要
对38Cr Mo Al A钢制齿轮进行调质处理和去应力处理后,釆用可控气氛渗氮炉进行渗氮处理,通过调整渗氮温度、保温时间、氨气分解率等参数进行工艺试验,最终采用预氧化两段快速渗氮法进行齿轮加工。工艺参数为:调质处理淬火温度930~950℃,回火温度610~650℃。去应力处理温度540~560℃。渗氮预氧化温度350~400℃,保温0.5 h,继续升温至渗氮温度490℃,保温3.5 h,氨气分解率40%~50%,继续升温至510℃,保温21 h,氨气分解率65%~75%,通入氨气或氨气裂解气冷却至150℃出炉。结果表明,按上述工艺参数加工齿轮的质量检验情况为:心部硬度30~31 HRC,渗层深度0.31~0.37 mm,渗氮层显微组织4级,白层厚度0.002 mm,渗氮层脆性1级,渗氮面表面硬度1093~1122 HV5,渗氮面精加工后表面硬度991~1012 HV5,均能满足设计要求。
38CrMoAlA steel gears were quenched and tempered,then gas nitrided with a controlled atmosphere nitriding furnace. The process tests were performed by adjusting parameters such as nitriding temperature,holding time,and ammonia decomposition rate,finally the pre-oxidation two-stage rapid nitriding method was used for gear processing. The process parameters include: the quenching temperature is 930-950 ℃,the tempering temperature is 610-650 ℃,the stress-relieving treatment temperature is 540-560 ℃,the nitriding preoxidation temperature is 350-400 ℃,holding for 0. 5 h,continue to heat up to the nitriding temperature of 490 ℃ and holding for 3. 5 h with ammonia decomposition rate of 40%-50%,then heat up to 510 ℃ and holding for 21 h with ammonia decomposition rate 65%-75%,finally introducing ammonia or ammonia cracked gas into the furnace,cooled down to 150 ℃. The quality inspection results of the gear processed according to the above process parameters show that the hardness of the core is 30-31 HRC,the depth of penetration layer is 0. 31-0. 37 mm,the nitriding layer microstructure is grade 4,the thickness of the white layer is 0. 002 mm,the nitriding layer brittleness is level 1,the surface hardness of the nitriding surface is from 1093 HV5 to 1122 HV5,and the surface hardness of the nitriding surface after finishing is 991 HV5 to 1012 HV5,all of which can meet the design requirements.
38CrMoAlA steel gears were quenched and tempered,then gas nitrided with a controlled atmosphere nitriding furnace. The process tests were performed by adjusting parameters such as nitriding temperature,holding time,and ammonia decomposition rate,finally the pre-oxidation two-stage rapid nitriding method was used for gear processing. The process parameters include: the quenching temperature is 930-950 ℃,the tempering temperature is 610-650 ℃,the stress-relieving treatment temperature is 540-560 ℃,the nitriding preoxidation temperature is 350-400 ℃,holding for 0. 5 h,continue to heat up to the nitriding temperature of 490 ℃ and holding for 3. 5 h with ammonia decomposition rate of 40%-50%,then heat up to 510 ℃ and holding for 21 h with ammonia decomposition rate 65%-75%,finally introducing ammonia or ammonia cracked gas into the furnace,cooled down to 150 ℃. The quality inspection results of the gear processed according to the above process parameters show that the hardness of the core is 30-31 HRC,the depth of penetration layer is 0. 31-0. 37 mm,the nitriding layer microstructure is grade 4,the thickness of the white layer is 0. 002 mm,the nitriding layer brittleness is level 1,the surface hardness of the nitriding surface is from 1093 HV5 to 1122 HV5,and the surface hardness of the nitriding surface after finishing is 991 HV5 to 1012 HV5,all of which can meet the design requirements.
引文
[1]郭起跃.内齿轮气体渗氮处理[J].金属热处理,2014,39(9):79-81.Guo Qiyue.Gas nitriding treatment of internal gear[J].Heat Treatment of Metals,2014,39(9):79-81.
[2]刘龙明.调质工艺对结构钢渗氮层深度的影响[J].金属热处理,2014,39(11):135-136.Liu Longming.Effect of quenching and tempering on nitrided case depth of structural steel[J].Heat Treatment of Metals,2014,39(11):135-136.
[3]余学华,李泉,李炜斌.38Cr Mo Al A锥齿轮气体渗氮处理质量控制[J].齿轮传动网,2010(9):8-12.
[4]金荣植.齿轮热处理手册[M].北京:机械工业出版社,2015.
[5]吴元徽.38Cr Mo Al A钢制镗杆渗氮处理的一点体会[J].热处理技术与装备,2010,31(2):55-57.Wu Yuanhui.Some experience about nitriding of boring shaft of38Cr Mo Al A steel[J].Heat Treatment Technology and Equipment,2010,31(2):55-57.
[2]刘龙明.调质工艺对结构钢渗氮层深度的影响[J].金属热处理,2014,39(11):135-136.Liu Longming.Effect of quenching and tempering on nitrided case depth of structural steel[J].Heat Treatment of Metals,2014,39(11):135-136.
[3]余学华,李泉,李炜斌.38Cr Mo Al A锥齿轮气体渗氮处理质量控制[J].齿轮传动网,2010(9):8-12.
[4]金荣植.齿轮热处理手册[M].北京:机械工业出版社,2015.
[5]吴元徽.38Cr Mo Al A钢制镗杆渗氮处理的一点体会[J].热处理技术与装备,2010,31(2):55-57.Wu Yuanhui.Some experience about nitriding of boring shaft of38Cr Mo Al A steel[J].Heat Treatment Technology and Equipment,2010,31(2):55-57.