Effect of Normalizing Treatment on Wear Characteristics of U75V Flash-Butt-Welded Joints in Coastal Environment

Abstract To evaluate the frictional service behavior of steel rails in marine environments and enhance the reliability of railway transportation, the friction and wear performance of U75V steel rail flash-butt-welded joints (normalized and nonnormalized) in a simulated seawater environment was investigated using a high-speed reciprocating friction and wear tester. The base metal exhibited superior friction performance (friction coefficient of 0.26) to the welded joints in the seawater environment. In addition, the normalized joint exhibited improved wear characteristics relative to the nonnormalized joint. These findings indicate (i) that welded joints have inferior wear performance to the base metal and (ii) that normalizing treatment reduces the grain size while increasing the hardness and toughness within the heat-affected zone of steel rail welds, thereby improving their overall friction properties. In the seawater environment, various ions collectively contribute to the formation of a surface lubrication layer on the worn surfaces, enhancing the overall friction-wear performance of the U75V steel rails but concurrently reducing the corrosion resistance of the material.