Characterization of carburized 14Cr14Co13Mo4 stainless steel by low pressure carburizing

摘要

The case-hardened 14Cr14Co13Mo4 martensitic stainless steel is carburized by low-pressure carburizing method. Plenty of second phase particles appear in the case layer. C concentration is measured by Carbon and Sulphur analyzer. Precipitation of second phase induces the improvement of C concentration in case layer. XRD results indicate that the second phase is composed of M23C6, M6C, M7C3 and intermetallic chi phase. EBSD results show layering distribution of carbides varied with C concentration. Phase diagram of 14Cr14Co13Mo4 steel is calculated by Thermo-Calc software to explain the phase transformation during the carburizing. Low-pressure carburizing process is simulated by DICTRA software to explain C diffusion in 14Cr14Co13Mo4 steel. The simulated C concentration profile agrees well with the experimental measured carbon values, which means that low-pressure carburizing parameters can be optimized by this modeling method.