电脉冲的热效应对淬硬轴承钢硬车性能的影响

The purpose of this article is to explore the influence of thermal effects under electric pulse-assisted hard turning on the machining process of ZGCr61 hardened bearing steel. By investigating the influence of different initial temperature (25, 70, 90, 110, 130 ℃) of the workpiece surface on the cutting temperature, chip formation, surface roughness, workpiece surface work hardening, and microstructure of the workpiece surface strengthening layer, the study aims to reveal the mechanism of thermal effects on the machining process of hardened bearing steel. As the initial temperature of the workpiece surface increases, the plasticity of ZGCr61 hardened bearing steel increases slightly, the cutting temperature decreases slightly, the sawtooth characteristics of the chips are weakened, and the shear strain in the shear band decreases by 30.7%. The height of the cutting ridge on the workpiece surface gradually decreases, and the adhesion defects of the chips decrease. The minimum surface roughness can reach 0.288 μm, which is 7.9% lower than that obtained by conventional turning. When the initial temperature of the workpiece surface is 110 ℃, the depth of the surface strengthening layer reaches 8.78 μm, which is 59.9% higher than that obtained by conventional hard turning. Within a certain range, the initial temperature of the workpiece surface can effectively reduce the cutting temperature and weaken the sawtooth characteristics of the chips. At an appropriate initial temperature, the thermal effect promotes dynamic recrystallization behavior in the plastic deformation layer on the workpiece surface, and the work hardening rate slightly decreases. However, when the initial temperature of the workpiece surface is higher, oxidation reactions occur on the machining surface, increasing hardness and generating more frictional heat between the workpiece and the tool face. This results in a sharp increase in cutting temperature, more pronounced sawtooth characteristics of the chips, and a decrease in workpiece surface quality.