The impact of pre‐nitriding on the microstructure and mechanical properties of the carburized surface layer in a martensitic stainless steel

In this study, it was proposed to obtain favourable combination of microstructure and mechanical properties of a martensitic stainless steel 14Cr14Co13Mo5 by pre-nitriding method before carburizing and appropriate heat treatment processes. The result indicated that the effective hardened layer depth was increased by 32% to 0.66 mm and the hardness was significantly improved by pre-nitriding. The CLSM and EBSD showed the pre-nitriding could effectively refine martensite substructure of the carburized layer after quenching due to the refinement of prior austenite grain. In addition, plenty of second phase particles M2N with finer size appeared at the same case layer depth instead of coarse M23C6 in the specimen pre-nitrided, which optimize microstructure of the case layer. This article is protected by copyright. All rights reserved.