It has been established that laser cladding technique is useful for enhancing surface performances, hence extending the life of many components in severe corrosive-wear environments. However, a comparative study of the surface performances of laser coatings made via powder and wire feeding systems has not been performed. Inconel 625 powder and wire were deposited on the AISI 304 substrate using similar processing parameters. The microstructure, together with the depth of substrate penetration and the degree of dilution of the deposited tracks, was examined using an optical microscope and a scanning electron microscope (equipped with an energy-dispersive spectrometer). The micro-hardness was measured using a Vickers hardness tester. At optimized parameters, laser tracks of Inconel 625 wire and powder had a strong metallurgical bond at the track–substrate interface and no crack and pore were deposited. Due to the higher laser beam infiltration and a larger depth of substrate penetration, higher substrate dilution was observed in the powder-fed tracks. The tracks comprise continuous ϒ-matrix and secondary compounds (rich in Nb and Mb). However, finer dendritic microstructure and higher number density of inter-dendritic precipitates were observed in a typical powder laser track compared with the corresponding wire laser track. The typical powder laser track demonstrated higher hardness (245 HV_0.3) compared with the corresponding wire laser track (224 HV_0.3).

Rolling contact fatigue, amongst other mechanisms of wear, between railway track and train wheel ensures that periodic replacement of worn track and other key components such as switches must be undertaken. The cost associated with repairing/replacing track is significant. This places a financial burden upon the rail network provider, creates a significant carbon footprint associated with remanufacture of track, and also interruption to train services. It is proposed that laser cladding, when deployed strategically, can reduce the costs associated with replacing worn track by enhancing the longevity of new rail components (preservice) and also for the repair of sections of track which are prone to excessive wear (in service). This will lead to a cheaper, more reliable, and sustainable rail network. This paper details a series of investigations undertaken to laser clad with premium wear resistant alloys (nickel alloy, Stellite 6, maraging steel, and hadfield steel) to much cheaper rail material substrates. The methodology for process optimization is presented, and the specimens are characterized for suitability. Laser cladding is demonstrated to be a viable solution to repair worn track, and a deposition process for actual track sections is presented.