关键词: 激光, 振镜, 高碳钢, 异质结构, 抗弯性能

Abstract: Brittle hardened layer of high carbon steel formed in the laser surface treatment tends to cause deterioration of overall mechanical properties. In order to improve the overall mechanical properties after laser quenching, a galvanometer laser with a spot diameter of 0.12 mm was used for multi-pass rapid scanning to fabricate heterogeneous structures with alternating soft and hard distribution on the surface of the 65Mn steel. The influence of surface heterostructures on bending resistance was studied, and the fracture behavior was analyzed using finite element simulation. The results show that after the laser treatment, the surface peak hardness increases by approximately 1.3 times. When the distance between adjacent passes is 0.084 mm, a heterogeneous structure composed of hard martensite and soft tempered martensite is formed on the surface. When the distance between adjacent passes is 0.214 mm and 0.284 mm, a heterogeneous structure composed of hardened zone and substrate zone is formed on the surface. Under the bending loads, the hard and soft zones of the heterogeneous structure undergo coordinated deformation, and the stress transferred from the hard zone to the soft zone, which suppresses the formation of cracks and prevents the deterioration of bending property. When the distance between adjacent passes is 0.148 mm, no heterogeneous structure is formed on the surface, and the bending property deteriorates. The hardened layer shows brittle fracture, but the substrate region still primarily shows ductile fracture.

Key words: laser, galvanometer, high carbon steel, heterostructure, bending property