Abstract:
The quenching-tempering pretreatment and pseudo-carburizing pretreatment of 18CrNiMo7-6 steel were carried out respectively, and then laser quenching was carried out under different laser power (1 000, 1 500, 2 000, 2 500, 3 000, 3 500 W) and different scanning speed (2, 4, 6, 8, 10, 12 mm · s
−1). The effects of laser power and scanning speed on the microstructure, hardness and depth of the surface hardening layer were studied. The results show that after laser quenching, the surface hardened layer microstructure of pseudo-carburizing and quenching-tempering pretreatment was mainly composed of low carbon martensite. With the increase of laser power or the decrease of scanning rate, the hardened layer depth of the two pretreatment test steels increased. Under the same laser power or scanning speed, the hardened layer depth of the pseudo-carburizing pretreatment test steel was larger, and the hardness of the hardened layer was slightly higher. The hardness of hardened layer after laser quenching was lower than that after carburizing quenching (700 HV).