Study on strip WEA wear damage and fatigue spalling of U71MnG rail material by laser quenching treatment

The wear damage and fatigue spalling behaviors of the martensite strip white etched area (WEA) prepared by subjecting the U71MnG steel to laser quenching were studied. The results showed that the wear mechanism of the strip WEA surface changed from a combination of oxidation wear and adhesive wear to oxidation wear with increasing number of cycles. The uncoordinated deformation of the substrate and strip WEA initiated the formation of cracks at their interface. Moreover, the low thickness of WEA at the initial position and plastic deformation of the substrate in front and below accelerated the WEA spalling. At the middle position, the increase in the WEA bulge made it bear a larger load, leading to a more significant rheological displacement of the strip WEA than that of the substrate. The cracks were preferentially initiated at the interface and then propagated to the surface and depth of WEA to form branch cracks. The main crack propagated through WEA to the underlying substrate, causing severe spalling. At the end position, the plastic flow of the substrate formed the sheet metal on the strip WEA surface.