Surface integrity of form grinding 20CrMnTi gear based on a new microcrystalline corundum wheel

To study the surface integrity of 20CrMnTi gears for form grinding by a microcrystalline corundum wheel, a grinding experiment on 20CrMnTi gear was performed. Furthermore, the effects of wheel speed, axial feed rate, and radial feed on tooth surface roughness, hardness, microstructure, and residual stresses of the surface/sub-surface were studied. The mechanism of the damage caused by grinding and micro-cracks was discussed. The results show that the effect of radial feed on the surface roughness is the most significant. The wheel speed is then the second most significant, and the axial feed rate is the least significant. In addition, an excessive grinding temperature leads to grinding burns, which the quenching burns cause the surface hardness to increase by 5% -20%, and the tempering burns cause the surface hardness to drop by varying degrees. The surface/subsurface structure is composed of a white layer, dark layer, and bulk material, with the white layer on the top and the bulk material being on the bottom. The white layer is composed of a dense martensitic structure, carbide, and retained austenite. The increase in the wheel speed and radial feed then increases the residual tensile stress caused by grinding. Surface residual compressive stress decreases and gradually changes to tensile stress. When the final residual tensile stress is greater than the breaking strength of the material, the surface produces micro cracks, compromising the integrity of the surface.