Experimental evaluation of novel alloy powders for extending service life of railway wheels worn by use

The wear of railway wheels and rails is one of the biggest challenges in the maintenance of transportation systems, and can represent up to 20–30 % of the total maintenance budget of a metro line. This underscores the importance of wheel wear and the need for efficient management to minimize operating costs. The aim of this study has been to investigate new alloy powders as suitable materials for reprofiling railway wheels and improving their wear resistance by using Laser Cladding technology. AISI 4140 and Stelite-6 powders have been selected as materials to be deposited on specimens extracted from the tread of a wheel used until its final service, and therefore, on hardened material, trying to reproduce real conditions as closely as possible. The bonding quality has been checked by examining the coating geometry in an Optical Microscope, and its microstructure and residual stress have been studied by Energy Dispersive X-ray Spectroscopy and X-ray Diffraction. Wear tests have been performed in a ball-on-disk tribometer in order to characterize the friction behaviour and evaluate the wear resistance of cladded and uncladded specimens. The results provided that AISI 4140 can match the wear behaviour of the wheel and that it could be appropriate for use in reprofiling applications.