18CrNiMo7-6和20CrNi2Mo钢渗碳工艺参数优化与应用

Optimization and application of carburizing process parameters for 18CrNiMo7-6 and 20CrNi2Mo steels

对不同渗碳工艺下的18CrNiMo7-6和20CrNi2Mo钢淬火后进行显微组织观察和硬度测试。结果表明,为使18CrNiMo7-6钢获得弥散分布的颗粒状碳化物的渗层组织和较高的表面硬度,采用的强渗和扩散碳势分别为1.05%和0.80%,20CrNi2Mo钢采用的强渗和扩散碳势分别为1.25%和0.90%。造成这种差异的主要原因是18CrNiMo7-6钢中富含碳化物形成元素Cr,而20CrNi2Mo钢富含非碳化物形成元素Ni。

The microstructure and hardness of 18CrNiMo7-6 and 20CrNi2Mo steels quenched after different carburizing processes were studied.The results show that,in order to get dispersed grainy carbides in carburized layer and higher surface hardness,the Cp（the carbon potential of boost carburizing period）and the Cf（the carbon potential of diffusion period）of 18CrNiMo7-6 steel is 1.05%and 0.80%,while that of 20CrNi2Mo steel is 1.25%and 0.90%,respectively.The main cause of this difference locates in that the 18CrNiMo7-6 is rich in carbide forming elements such as Cr,while the 20CrNi2Mo is rich in the noncarbide forming elements such as Ni.