Abstract: It was easy to produce a white layer on the machined surfaces of hardened steels, which had a serious impact on service performance of parts. To solve the problems of white layer formation, LAT was therefore proposed to replace conventional turning for hardened steels. FEM of thermal-mechanical coupling LAT processes was established by VDFLUX user subroutine. Based on simulation results of FEM and prediction model of critical cutting speed of white layer formation, the influences of different laser preheating parameters on critical cutting speed of white layer formation were analysed. The results show that the upper limit of the critical cutting speed of white layer formation may be increased by appropriately reducing laser power, increasing laser spot radius, and shortening the distance from laser spot to tool tip within the ranges of laser preheating parameters selected, such as laser power P is as 200~600W，laser spot radius R is as 0.5~0.9 mm，distance between laser spot and tool tip L is as 5~15 mm. Under the optimized laser preheating parameters(P=200 W, R=0.9 mm, L=5 mm), the critical cutting speed of white layer formation on the machined surfaces of hardened steels is higher than that of conventional cutting to about 26.09%.

Key words: laser-assisted turning(LAT), hardened steel, white layer, finite element model(FEM)

摘要： 淬硬钢已加工表面极易产生白层，对零件的服役性能造成很大影响，采用激光加热辅助车削替代常规车削来加工淬硬钢可解决白层形成的问题。利用VDFLUX用户子程序建立了热力耦合移动激光加热辅助车削过程有限元模型并进行仿真。基于有限元模型仿真结果和白层形成临界切削速度预测模型，分析了不同激光预热参数对白层形成临界切削速度的影响。结果表明，在选用的激光预热参数范围内（激光功率P为200~600 W，激光光斑半径R为0.5~0.9 mm，激光光斑到刀尖点的距离L为5~15 mm），适当减小P和L、增大R均能增大白层形成临界切削速度的上限，在优选的激光预热参数（P=200 W，R=0.9 mm，L=5 mm）下，淬硬钢已加工表面白层形成的临界切削速度较常规切削提高了约26.09%。

关键词: 激光辅助车削, 淬硬钢, 白层, 有限元分析