Prediction and Experimental Study of Critical Cutting Speed of White Layer Formation in LAT Hardened Steels

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%. © 2022, China Mechanical Engineering Magazine Office. All right reserved.