Study on surface residual stress of hardened 12Cr2Ni4A alloy steel by ultrasonic vibration-assisted ELID grinding

Hardened 12Cr2Ni4A is a kind of high-quality alloy steel material. Due to the comprehensive excellent mechanical properties of high strength, high hardness, good toughness, and good wear resistance, it is widely used to manufacture various mechanical structural parts, such as gears, worm gears, worms, shafts, etc. In order to ameliorate the stress state of the workpiece surface after ordinary grinding (OG) and improve the fatigue life of the workpiece. In view of the effect of grinding heat on surface residual stress, a mathematical model of surface residual stress of hardened 12Cr2Ni4A alloy steel by ultrasonic vibration-assisted ELID grinding (UVAEG) was established and verified by experiments. Ordinary grinding, ultrasonic vibration-assisted grinding (UVAG), and ultrasonic vibration-assisted ELID grinding were used to machine hardened 12Cr2Ni4A alloy steel. The stress state of the machined surface under different grinding methods is explored, and the influence of different parameters on the residual stress on the surface of the workpiece with ultrasonic vibration-assisted ELID grinding is analyzed. The experimental results show that the influence of grinding depth, ultrasonic amplitude, and duty cycle on the residual stress on the surface of the workpiece is basically consistent with the established residual stress model, which confirm the validity of the model. The residual compressive stress on the surface of ultrasonic vibration ELID grinding increases with the increase of ultrasonic amplitude and duty cycle, and shows a decreasing trend with the increase of grinding depth.