Optimization of high-speed grinding parameters for anti-fatigue performance of 20CrMnTi steel

High-speed grinding technology is being applied to the precision machining of 20CrMnTi steel gears, shafts and bearings suffering from fatigue damage. The response surface methodology (RSM) was used as an optimization method of high-speed grinding parameters to reach a higher anti-fatigue performance of 20CrMnTi steel workpieces. The mathematical formulas were established to clarify the effect of grinding parameters on surface integrity indexes including surface roughness, hardness and residual stress. The distribution of residual stress and the thickness of thermal influenced layer on the subsurface were measured, and the thermal field was analyzed by finite element simulation of grinding process. Results show that an appropriate increase in workpiece speed and a decrease in wheel speed and depth of cut can result in lower surface roughness and higher residual compressive stress to promote anti-fatigue performance. The thickness of the heat affected layer and grinding temperature is extremely sensitive to the depth of cut, which should be controlled below 15 μm to avoid embrittlement induced by re-quenching and subsurface heat damage. To improve anti-fatigue performance, the grinding parameters with wheel speed, workpiece speed and depth of cut of 90 m/s, 0.836 m/s and 12 μm with desirability function 0.931 are the ideal solution under the processing conditions in this study.