Experimental Study on Laser Quenching Hardening of 42CrMo Steel Surface

The laser quenching treatment of 42CrMo steel surface was carried out with a RFL - C3300 fiber laser, and the relations between the microstructure, hardness, depth, wear resistance of the hardened layer and the laser process parameters were analyzed by scanning electron microscope, optical microscope, stereomicroscope, vickers hardness tester and vertical universal friction and wear tester. Results showed that after laser quenching, the surface microstructure of the sample was refined, and the surface hardness and wear resistance were improved. When the laser power was 2 200 W, the scanning speed was 20 mm/s and the spot size was 12 mm × 2 mm, the surface microstructure of the sample was composed of fine martensites, a small amount of retained austenites and dispersed fine carbides. The average surface hardness reached 660 HV2 N, which was about 2.6 times that of the matrix. The friction coefficient stabilized at 0.4～0.6, which was about 25% lower than that of the matrix. The wear amount was 0.5 mg, which was 23.8% of that of the matrix.