High-temperature tribological characterisation of laser surface melted Ni-based superalloy

Laser surface treatment was performed on nickel-based superalloy to improve their high temperature tribological properties for enhanced service life specifically in gas turbine applications. The laser power and scan speed were strategically controlled to optimally refine the microstructure. The metallurgical and mechanical modifications in the treated area were studied to understand the refining mechanism. The coarser grains in the base material re-orient to fine dendrites during laser surface melting. The equiaxed grains are refined with increased laser power and reduced interaction time under the influence of higher cooling rate. The finely refined grains improve the microhardness of the treated surface. The tribological performance and its mechanism of the treated surfaces were evaluated at room temperature and at 500°C. A significant reduction in the wear rate was observed for the laser treated surface, where abrasion and adhesion found to be the dominant wear mechanisms.