Influence of laser surface melting on the micropitting performance of 35CrMo structural steel gears

This paper investigates the micropitting behavior of 35CrMo structural steel gears treated through laser surface-melted (LSM) treatment. Laser surface melting of 35CrMo structural steel gears was achieved by a 4.5 kW Nd:YAG pulsed laser with various laser energy densities. The microstructure and the phases present in the LSM gear teeth were analyzed by SEM and XRD. The FZG test rig was used for micropitting experiments. Post-test analysis included the weight loss measurement of gears (pinion and wheel). The micropits on the tooth flanks were inspected using SEM. XRD analytical results showed that martensite is the main phase in the LSM teeth flank. The LSM gears showed better micropitting performance as compared with the as-received one. The improvement in micropitting resistance of the LSM gears is due to grain refinement and solid solution hardening.