Effect of Ice Water on the Reciprocating Wear Behavior of Flash-Welded Joints in U71Mn Rails Used in High-Speed Railway

Abstract The operational reliability of high-speed railways in cold, wet environments, such as high-altitude regions, presents a significant challenge, particularly concerning the durability of flash-butt-welded rails. This study investigates the reciprocating sliding wear behavior and mechanisms of U71Mn steel rail flash-welded joints under both water and ice–water conditions. This study comparatively analyzed three critical zones: the base metal, the as-welded joint, and the normalized joint. The results indicated that the ice–water environment more strongly influenced the friction and wear properties than the water-only environment. Although the friction coefficients generally decreased in the ice–water mixture, the wear damage was significantly more severe for all materials. Notably, the base metal experienced a disproportionately larger increase in the wear-rate than the welded joints, revealing that environmental degradation critically depends on the microstructure. Microscopic analysis identified that the predominant wear mechanisms under ice–water conditions were abrasive and oxidative wear, with the base metal being particularly susceptible to crack propagation at the surface. These findings clarify the wear mechanisms of rail joints in icy environments and provide a foundational basis for developing strategies to enhance the low-temperature wear resistance of high-speed railway welds.