Study on the formation of surface affected layer in grinding ultra-high strength steel

An affected layer will be formed on workpiece surface in grinding process, which affects the fatigue strength and life. The simulation and experiment were used to study the grinding force, grinding temperature field, stress field, strain field, as well as the characteristics of the affected layer (residual stress, microhardness, and microstructure) in grinding AerMet100 with white alumina grinding wheel and CBN grinding wheel. The variation law of the grinding force, grinding temperature, equivalent stress field, and equivalent strain field during the grinding process and their influence on the formation of surface affected layer were revealed. The results show that the ground surface is mainly affected by grinding heat, while the grinding sub surface (i.e., plastic deformation zone) is greatly affected by plastic tensile (or compression) effect of grinding force; the microstructure of the ground surface deviates along the grinding direction and presents fibrous structure, with grain elongation, and when the grinding parameters are large, a white layer structure appears on the ground surface; the temperature rise softening effect for surface microhardness is the dominant factor with the white alumina grinding wheels; the metal strengthening effect for surface microhardness caused by mechanical plastic deformation of grinding force is the dominant factor with the CBN grinding wheels; for the white alumina grinding wheels, the residual tensile stress caused by grinding heat is relatively significant; for the CBN grinding wheel, the grinding surface generally presents residual compressive stress, and the residual compressive stress caused by mechanical plastic deformation caused of grinding force plays a dominant role.