Microstructure and Wear Performance Assessment of Laser Cladded Rail Steel for Service Life Extension at Sharp-Radius Curves

摘要

Excessive rail wear causes significant reduction in service life and increases the possibility of derailment. Sharp curves in particular, are more susceptible to wear than straights. Hence, the curved sections are manufactured from head hardened rail steel (R350HT grade) instead of the standard R260 rail steel due to their greater wear resistance. With the emergence of advanced rail systems, failures due to wear are still predominant, resulting in frequent maintenance or replacement of rails which is not cost effective. Hence, the prospect of repair via laser cladding has been studied to improve wear performance for extended service life and minimize financial burden. In this paper, the clad material's compatibility with R350HT grade rail steel is evaluated. The transition in microstructure across the interfacial zone from the clad to the substrate is presented along with the hardness profile. Laboratory based ball-on disc wear tests serve as a preliminary indicator of the wear performance of the laser cladded R350HT grade rail steel. It is evident from the study that laser cladding of R350HT grade rails is feasible with capability to enhance service life at sharp-radius curves when adopted strategically.