真空渗碳处理38CrMoAl渗氮钢的微观组织及氢脆敏感性分析  

Microstructure and Hydrogen Embrittlement Sensitivity of 38CrMoAl Nitriding Steel Treated by Vacuum Carburizing

作　　者：赵华瑞[1] 丁彦霞 ZHAO Hua-rui;DING Yan-xia(Department of Automobile Technology,Xinxiang Vocational and Technical College,Xinxiang 453000,China;School of Physics and Material Science,Henan Normal University,Xinxiang 453000,China)

机构地区：[1]新乡职业技术学院汽车技术系,河南新乡453000 [2]河南师范大学物理与材料科学学院,河南新乡453000

出　　处：《材料保护》2021年第8期56-60,共5页Materials Protection

基　　金：国家自然科学金项目(51775172)资助。

摘　　要：为了满足汽车轻量化对材料性能的要求,选择齿轮用38CrMoAl渗氮钢作为测试材料,以电化学充氢方法与慢应变拉伸相结合的方式测试了真空渗碳(Vacuum Carburizing,VC)试样的氢脆敏感性,同时与淬火+低温回火态(Quenching+Low-Tempering,QL)处理试样进行了比较。研究结果表明:QL试样中形成了均匀形态的低碳回火马氏体;VC试样渗碳层中以高碳回火马氏体为主,存在少量的残余奥氏体。VC试样在表面部位的最大硬度达到了732 HV;QL试样在450 HV附近。对QL试样进行充氢后表现出了与初始试样接近的拉伸强度,而断后伸长率显著减小,计算相对断后伸长率差异得到QL试样氢脆敏感性指数(HEI)为54.3%。对38CrMoAl渗氮钢进行渗碳处理后会引起其氢脆敏感性的快速提高。对QL试样充氢处理后试样产生了更明显的脆性断裂,表现出了与高强度马氏体钢氢致断裂相近的特性;充氢后VC试样在断裂后形成了许多韧窝状的结构,呈现韧性断裂的特性。In order to meet the requirements of material properties for automotive lightweight,38 CrMoAl nitriding steel for gear was selected as the test material.The hydrogen embrittlement sensitivity of vacuum carburizing(VC)samples was tested by electrochemical hydrogen charging method combined with slow strain tensile,which was compared with quenching and low tempering(QL)treated samples.Results showed that the uniform form of low carbon tempered martensite was formed in the QL sample.Carburized layer of VC sample was dominated by high carbon tempered martensite,and there was a small amount of residual austenite.VC sample reached the maximum hardness of 732 HV on the surface while QL sample was near 450 HV.After hydrogen charging,the tensile strength of the QL sample was close to that of the original sample while the elongation after fracture(HEI)was significantly reduced.Calculating the difference of relative elongation after fracture indicated that the hydrogen embrittlement sensitivity index(HEI)of QL sample was 54.3%.The hydrogen embrittlement sensitivity of 38 CrMoAl nitriding steel was increased rapidly after carburizing treatment.After hydrogen charging treatment,QL sample had more obvious brittle fracture,which was similar to the hydrogen induced fracture of high strength martensitic steel.VC samples treated with hydrogen charging formed many dimple-like structures after fracture,showing the characteristics of ductile fracture.

关 键 词：氢脆 渗氮钢 真空渗碳 微观组织 力学性能 

分 类 号：TG142[一般工业技术—材料科学与工程]