Repair of light rail track through restoration of the worn part of the railhead using submerged arc welding process

Abstract

A surface worn C-Mn rail is repaired by retrieving the lost part of the railhead using a commercial rutile flux-cored wire submerged arc welding (SAW) method. Optical microscopy (OM), scanning electron microscopy (SEM), electron-dispersive X-ray spectroscopy (EDS), and Rockwell B hardness test are employed to investigate the properties of the repaired rail specimen. After the first set of analysis, the as-repaired rail is heated up to 1100 °C and water-quenched to room temperature to increase hardness. Each specimen is analytically partitioned into three zones including weld zone (WZ), heat-affected zone (HAZ), and the unaffected rail substrate. The as-repaired rail WZ is primarily composed of pearlite, ferrite, and austenite with a low hardness of 80 HRB, whereas the austenite phase is gone in the as-quenched rail and a massive extent of carbides are precipitated which increased hardness to 95 HRB. The microstructure of the HAZ in the as-repaired sample is a uniform distribution of fine-grained ferrite, pearlite, and carbide with the hardness of 92 HRB, while the microstructure of the identical zone in the as-quenched specimen is mainly martensitic-pearlitic with the highest average hardness among all zones, 110 HRB. The results presented an immense potential for SAW in rail repair.