Research on 40Cr Laser Quenching Process for Guide Rail

Abstract

In this study, the use of laser quenching was explored as a method of surface strengthening for 40Cr steel utilized in machine tool guideways. The impact of various process parameters, including laser power, scanning speed, and spot radius, on the hardness and depth of the quenched layer was evaluated. The results indicated that the optimal process parameters were a laser power of 2000 W, a scanning speed of 20 mm/s, and a spot radius of 3 mm, which resulted in a maximum quenched layer hardness of 889 HV, an average quenched layer hardness of 764 HV, and a quenched layer depth of 0.7 mm. The application of the laser quenching process through multiple passes was shown to further improve the material properties, resulting in a hardness increase from 749 HV in a single quench to 980 HV in 16 quenches and a corresponding increase in the quenched layer depth from 0.2 mm to 0.9 mm. The hardness of the surface treated by the lap quenching process increased from 250 HV after a single quench to 390 HV after repeated quenching, leading to a more uniform distribution of hardness on the material surface. Furthermore, the average coefficient of friction decreased from 0.67 to 0.37, and the weight loss due to wearing was reduced from 9.7 mg to 1.7 mg after the staggered repeated quenching process.