Influence of manufacturing conditions of carbonitriding on formation of surface layers and protective properties of hot-work structural steel

Abstract

In this work, the deposition conditions and phase composition of a carbonitrided coating on a complex alloyed hot-work 25Kh3M3NBTsA structural steel are studied using thermodynamic modeling and structural methods. It is shown that the main phases of the surface layers of carbonitrided steel are the solution of nitrogen and carbon in α-Fe, carbonitride, iron nitrides, and chromium and iron carbides. According to the results of thermodynamic analysis, carbide precipitate based on the Fe₃C phase and CrN-based nitride precipitate can be formed. The possible reasons for the absence of the CrN phase in experimental data are indicated. It is shown that the wear rate of carbonitrided coatings is determined by the microhardness of the carbonitrided layer, whereas the fatigue life is related to the crack propagation rate.