Microstructure and Wear Behavior of Repair Weld on the Flash-Butt Welded Rail

This study aimed to evaluate the potential of using a standard arc welding process to repair surface defects in flash-butt welded (FBW) rails by examining their microstructural, mechanical, and tribological properties. Macrostructural analysis, optical microscopy (OM), field emission scanning electron microscopy (FESEM), hardness testing, and wear tests were employed to compare original and repaired FBWs. The repaired weld revealed fine pearlite in the heat-affected zone (HAZ) and acicular ferrite in the weld metal, while hardness results indicated a higher and more uniform distribution across the weld metal and HAZ than in the original FBW. Wear tests showed that both welds had similar coefficients of friction and wear track widths, but the repaired FBW demonstrated less weight loss. SEM analysis identified micro-ploughing and micro-cutting as dominant wear mechanisms in the original FBW, whereas the repaired FBW primarily exhibited micro-ploughing and oxide delamination. These findings indicate that arc welding repair not only improves hardness uniformity but also enhances wear resistance without significantly affecting frictional behavior. In conclusion, the arc welding process can be considered an effective method for restoring the surface integrity of FBW rails, with the implication that its application in rail maintenance may extend rail service life and reduce replacement costs.