Experimental analysis of residual stress and hardness of 18CrNiMo7-6 steel in high speed cylindrical grinding

For 18CrNiMo7-6 carburized steel workpiece, a single factor test was designed studying the wheel speed, the workpiece speed, the feed rate and the abrasive size. X-ray residual stress analyzer and micro hardness tester are used to detect the residual stress and hardness. The results show that high-speed cylindrical grinding can introduce residual compressive stress to the surface of the workpiece, and that the compressive stress in the X direction is less than that in the Y direction. Meanwhile, high-speed cylindrical grinding can improve the surface hardness of the workpiece. With the increase of wheel speed, the compressive stress increases first and then tends to be stable, while the hardness decreases first and then increases and the minimum value is obtained when the speed is 75 m/s. With the increase of workpiece speed, the change of residual compressive stress and hardness is not monotonic. The feed rate has a great influence on the compressive stress and hardness of the workpiece surface, which are reduced in general after linear fitting. Grinding wheels with different CBN abrasive grain sizes produce different compressive stress and hardness on the surface of the workpiece, namely: M10/20 produces the largest, followed by 120/140, and then 230/270 the smallest. On the surface of the workpiece, the hardness is low when there is tensile stress, and the hardness is high when there is compressive stress.