Impact Wear of Flash- and Aluminothermic-Welded Hypereutectoid Steel Rail Joints

Abstract

High-speed, high-load railway development has necessitated a deeper understanding of the wear behavior and mechanism of welded steel railway joints subjected to repeated impact. Under different simulated impact loads and impact cycles, the impact damage evolution and wear mechanism of flash- and aluminothermic-welded joints in the weld and heat-affected zones and base material were compared and analyzed. The results show that the impact wear severity increased with impact cycle and load. With increasing impact load and cycle, the impact wear in the welded rail joints progressed through plastic deformation, partial pitting failure, fatigue crack propagation, and spalling from the synergistic effect of fatigue and oxidation wear. The degree of impact wear increased in the order of the softening part of the heat-affected zone, welding seam, and base material. Comparison of the wear performance of the two kinds of welded joints showed that the fatigue resistance of the flash-welded joint was higher than that of the aluminothermic-welded joint under low impact loads and cycles. In contrast, under high impact loads and cycles, the wear degree of the flash-welded joint increased sharply upon reaching a critical value and was more severe than that of the aluminothermic-welded joint.