Influence of microstructure of superficial layer on the mechanical properties of nitrocarburized P6M5 steel grade

摘要

This article presents the results of investigations carried out in order to determine the correlation between the microstructure of carbide layers formed on P6M5 steel grade and its microstructure, as well as wear resistance. Presented here are results of a stereo analysis of carbonitrides formed in the diffusion cases as the result of nitrocarburizing processes. The phase composition and microstructure of the nitrocarburized cases is described. Processes of strengthening by diffusion were carried out in a powder pack, employing temperatures of 450, 500 and 550°C, while the time of treatment at each temperature was 6 h. The effect of treatment temperature on the surface taken up by carbonitrides, as well as their size and shape is presented. The correlation is discussed between the characteristic features of microstructure on the one hand and microhardness and wear resistance on the other. The article contains the results of investigations of the effect of process temperature on microhardness. Friction wear tests were conducted by the three cylinder method, employing loads of 50 and 400 MPa.