摘要
针对20Cr2Ni4A钢制造的中大型齿轮在不允许冷处理的条件下渗碳淬火硬度偏低的问题,通过对渗碳淬火碳势、中间高温回火工艺、淬火温度的优化,在不冷处理的情况下使齿轮硬度提高了2 HRC以上至58~61 HRC,显微组织良好,达到了预期目的。试验发现,该材料渗碳后经过高温回火再重新加热淬火时,为了提高表面及次表面硬度,渗碳扩散碳势、渗碳降温保温阶段碳势和淬火碳势在碳化物不超标的前提下要尽量提高;反复试验与检测证明,中间高温回火也会导致渗碳层一定深度内碳含量的降低,从而影响渗碳淬火硬度,故高温回火时不仅要注意回火不足更要防止过回火,高温回火次数过多时间过长,淬火后硬度不升反降。
In view of the insufficient hardness of large gears made of 20Cr2Ni4A steel after carburizing and quenching but not allowing refrigerating treatment,the hardness of the gear is increased by more than 2 HRC to 58-61 HRC free of refrigerating treatment,through the optimization of carburizing and quenching carbon potential,intermediate high temperature tempering process and quenching temperature,meantime,the good microstructure is obtained.It is found that in order to improve the surface and subsurface hardness,the carbon potential should be increased as high as possible under the premise that the carbides do not exceed the standard,when the steel is hardened by reheating after carburizing and high temperature tempering.Repeated tests show that the intermediate high temperature tempering can also reduce the carbon content in a certain depth of the carburized layer,which can affect the carburizing and quenching hardness.Therefore,both insufficient tempering and over tempering should be prevented,especially the latter.If the tempering times are too many and the each time is too long,the hardness will be lower after quenching.
作者
赵少甫
许鸿翔
王红伟
郭敬强
李子岩
陈岩
Zhao Shaofu;Xu Hongxiang;Wang Hongwei;Guo Jingqiang;Li Ziyan;Chen Yan(Zhengzhou Research Institute of Mechanical Engineering Co.,Ltd.,Zhengzhou Henan 450001,China)
出处
《金属热处理》
CAS
CSCD
北大核心
2021年第7期120-125,共6页
Heat Treatment of Metals
基金
国家重点研发计划(2019YFB2006403)。
