Improvement of the wear resistance of 20CrMnTi steel gear by discrete laser surface melting

Abstract

This paper studied the effect of discrete laser surface melting on the wear resistance of gears. The radial ribs on the surface of intertidal shellfish had the function of anti-abrasion. The discrete laser surface melted (DLSMed) units were processed on the gear surface, and they looked like radial ribs.The microstructure and wear morphology of the DLSMed unit were observed under a scanning electron microscope. The phase composition and residual stress of the DLSMed unit were analyzed through a X-ray diffractometer. The hardness of the DLSMed unit was measured with a microhardness tester. The roughness of the DLSMed unit was measured with a surface topography meter. The wear test of gear was carried out with a Forschungsstelle für Zahnräder und Getriebebau (FZG) testing machine. The lubricating oil analysis technology was used as the evaluation basis of gear wear performance. The experimental results showed that discrete laser surface melting could refine the grain on the gear surface, improve the hardness of the gear, and form residual compressive stress on the gear surface. The cross-sectional area of the DLSMed unit gradually decreased as the laser scanning speed increased. As the cross-sectional area of the DLSMed unit decreased, the wear resistance of the gear also deteriorated. Finally, the wear mechanism of the DLSMed gear was discussed from many aspects.