Investigation on the rolling wear and damage properties of laser discrete quenched rail material with different quenching shapes and patterns

Abstract The influence of laser discrete quenching (LDQ) on the rolling wear and damage properties of the U75V rail material was investigated. Different quenching shapes (including spot, strip, and grid shapes) and different quenching patterns (including different diameters of quenching spots, distances between adjacent spots, and directions of quenching strips) were studied. The results indicated that LDQ created martensite regions with an average hardness of around 927 HV0.5 on the rail surface. LDQ improved the wear resistance of rail material. On the untreated rail roller and in the untreated zones on treated rail rollers, cracks propagated with small angles of around 4–17° and small depth of around 11–22 μm. In the quenching regions, cracks propagated with large angles of around 58–80° and large depth of around 73–263 μm. The wear resistance and fatigue resistance of treated rail rollers were improved with the increase in the diameter of quenching spots and the decrease in the distance between adjacent spots. The wear resistance and fatigue resistance of treated rail with quenching grid were better than treated rail with quenching strips.