Study on the distribution of hardening layer of 40Cr and 45 steel workpiece in grind-hardening process based on simulation and experiment

摘要

Hardening layer with a certain thickness can be formed on the workpiece surface after grind-hardening process. It can provide a better using performance for the workpiece. Therefore, the study on surface hardening layer and its distribution has important meaning to improve the using performance of the workpiece after dry grinding process. The paper analyzed the hardness, thickness, and its consistency of hardening layer through grind-hardening experiment using 40Cr and 45 steel. And then the paper studied the temperature field of surface hardening layer on the workpiece by FEM simulation. The cooling rate v (mc) could be calculated by using temperature-time curve. The distribution of hardness and thickness of surface hardening layer was also obtained. Combined with experiment results, the characteristic of the consistency of surface hardening layer was analyzed. The result showed that the hardness of the surface hardening layer would increase with the increasing of depth of cut a (p) and feeding rate v (w). The thickness of the surface hardening layer also increases with the increasing of a (p), but it decreases with the increasing of v (w). The Cr element benefited the formation of martensite when the depth of the cut is small. But when the depth of the cut reaches to a certain value, the effect of Cr element could no longer be obvious. The results also showed that the consistency of intermediate area on the workpiece is much better than that of the cutting-in area and cutting-out area. Therefore, in order to obtain surface hardening layer with the suitable hardness and thickness, both technological parameters and materials should be chosen appropriately.