Effect of Laser Remelting on the Mechanical Behaviour of Inconel 625 Cold-Sprayed Coatings

Abstract

Abstract Ni base overlay coatings are being used to protect metallic engineering components in extreme conditions and actually traditional thermal spray deposition technologies such as Air Plasma Spraying (APS) and High Velocity Oxy-Fuel (HVOF) are mainly used to deposit these materials. However, Coldspray is receiving increased attention during the last years because of the lower spraying temperature required to deposit metallic coatings avoiding oxidation and reducing the coating porosity and the amount of residual stresses. The adhesion to the substrate and the growth mechanism of coldspray deposits are based on plastic deformation of impinging particles, so, in the case of high strength materials such as for example Ni alloys, it could be a lack in plastic deformation leading to insufficient compactness of the coating, barrier properties and high temperature resistance. Further improvements in the coatings performances could be attained by post-deposition thermal treatments to enhance coating adhesion and barrier properties. In this sense, the aim of this study is to explore a two-step way to produce high performances Inconel 625 alloy coatings by coldspray deposition followed by a laser glazing treatment. Coldspray Inconel 625 alloy coatings has been deposited onto AISI304 steel substrates. Laser glazing is performed using high power diode laser (HPDL) ROFIN-SINAR 13DS; the local thermal treatment on the coating surface induce microstructural changes which could modify and improve the coating compactness and performances. Coating morphology and microstructure has been evaluated and reported both before and after laser consolidation as a function of different laser conditions.