滚动轴承钢碳氮共渗工艺研究

Study on Carbonitriding Process of Rolling Bearing Steel

以GCr15和GCr15SiMn轴承钢为研究对象,进行不同工艺的碳氮共渗热处理实验研究。利用光学显微镜观察试样热处理后的显微组织、晶粒度,利用X-射线衍射仪分析热处理后残余奥氏体的含量,利用硬度仪测量试样热处理后的硬度变化规律,研究共渗温度对渗层组织和性能的影响。研究结果表明:考虑碳氮共渗层深度、显微组织、晶粒度以及硬度综合因素,碳氮共渗温度控制在820℃,碳势控制在1.18%,进行淬火和低温回火的组织和性能较好。该工艺下增加冷处理,GCr15SiMn试样表面硬度从64.5 HRC提高至66.1 HRC,表面残余奥氏体量从22.1%下降至12.5%。冷处理有效降低了表面残余奥氏体含量。

GCr15 and GCr15SiMn bearing steel samples were used to conduct experiment studies on different processes of carbonitriding heat treatments.Using optical microscope,X-ray diffractometer,hardness tester,and other equipment,the microstructure,hardness,austenite grain size,and other microstructure and properties of the samples from different carbonitriding heat treatment processes were analyzed,and the effect of carburizing temperature on the microstructure and properties of the carburized layer was studied.The results show that,considering the comprehensive factors of carburizing layer depth,microstructure,grain size and hardness,the carbonitriding temperature is controlled at 820℃with the carbon potential of 1.18%,the microstructure and properties of the samples after quenching and low temperature tempering are relatively good.After the further cryogenic treatment of the GCr15SiMn steel sample,the surface hardness of the steel is increased from 64.5 HRC to 66.1 HRC,and the surface residual austenite content is decreased from 22.1%to 12.5%.The cryogenic treatment reduces the residual austenite content on the surface effectively.