Structural and Nanohardness of Laser Melted CM247LC Nickel-Based Superalloy

Nickel-based superalloy CM247LC is predominantly used for manufacturing turbine blades due to its notable characteristics. This alloy is majorly influenced by the prevailing environmental conditions that lead to the reduction in its tribological properties. Hence, this work attempted to evaluate the texture formations that take place during the laser melting of the cast CM247LC alloy. With the aid of optical microscopy and scanning electron microscopy, the structural transformation that happened during laser melting has been analyzed. The orientation of grains along with the texture was investigated using the electron backscatter diffraction method and inverse pole images. In addition, the hardness and surface roughness were offered by the as-cast (base), interface and laser melted layer were compared through nanoindentation testing. Results showed that the laser melted region contained a combination of columnar and equiaxed microstructure. The metal carbides were distributed throughout the melted surface and combined microstructures such as columnar and equiaxed grain structures were formed due to the effect of rapid heating and high cooling rate during laser melting. Moreover, the melted region exhibited lower indentation depth than that of the base region which proved that the laser melted CM247LC had higher hardness compared to that of the interface and as-cast CM247LC alloy.