Research of the wear resistance of 35CrMoA steel in laser quenching /nitrided layer

Laser quenching and nitriding treatment has been performed on 35CrMoA steel, and the microstructure, hardness and wear resistance of laser quenching/nitrided layer were investigated by means of OM, XRD and TEM, microhardness tester and wear equipment compared with the gas nitrided layers. The results show that both nitrided layer consisted of ε, γ´, and Cr₂N. The content of ε-Fe₃N is higher in the laser quenching/nitrided white layer while the content of the brittle ζ-Fe₂N is lower than that of the gas nitrided layer. Especially the Cr₂N particles are much finer. Spherical particles of cementite were formed in lower strip bainite. The scratch in worn surface of laser quenching/nitrided layer is shallow, but the gas nitriding worn surface has the deep plow furrow and flaking. After laser quenching/nitriding treatment, the depth of the nitrided layer increases, and hardness and wear resistance were improved dramatically.