Analysis of Measured and Predicted Residual Stresses Induced by Finish Cylindrical Grinding of High Speed Steel with CBN Wheel

Abstract

Inducing complex thermo-mechanical loads during grinding process of hard materials, such as high alloyed high speed steel, may affect the surface integrity and thus the performance of engineering parts. Residual stresses are considered as the most significant parameter which allows a good assessment of the performance of ground part. Earlier studies have alluded to the fact that the grinding process is usually the source of a tensile residual stresses on the part surface. In this paper, at first, experimental measurements of ground workpiece obtained by X-Ray diffraction show high level of compressive residual stresses generated in ground surfaces. To understand the origin of the sign of residual stresses, a Finite Element simulation model of finish cylindrical grinding with temperature dependent material properties was established and thermo-mechanical simulations were processed based on two-dimensional numerical simulation using SYSWELD 2010®software. The action of the CBN wheel on the workpiece is modeled by a moving equivalent heat flux on the top of the workpiece surface. The heat source profile derived from both analytical calculation and experimental results. The mechanical action of the wheel is simulated as a normal pressure distributed over abrasive grains of the contact zone. The distribution of the temperature and residual stresses was carried out. However the difference between simulated and measured results is significant. Based on further advanced characterizations of ground surface layer, it seems that thermo-mechanical model with equivalent loads is not sufficient to reproduce induced residual stresses occurred through plastic deformations and structure changes under given process conditions, wheel and material properties.