Investigating laser power in AM-LMD process on the Inconel 718 powder deposited profile microstructure, aiming to repair gas turbine blades

The purpose of this study was to evaluate the feasibility of repairing defective turbine blades made of Inconel 738 using additive manufacturing called laser metal deposition with the use of Inconel 718 powder. The deposition process was conducted on substrates using varying laser power, 150, 250 and 350 (W). The experimental results indicate that as the laser power is raised, there is a corresponding increase in the average of substrate melting depth, 33.42–405.12 (µm), the average of interface thickness, 2.85–10.20 (µm) and the amount of dilution, 0.036–0.684 (%). The substrate's volume percentage and the average size of the γ' phase exhibit larger values prior to the deposition procedure compared to the subsequent stages. The augmentation of laser power resulted in a proportional rise in both the volume percentage and average size of the γ' phase within the substrates. At the location near the interface of the first layer, graining is preferentially in the direction of heat transfer and crystal growth. A narrow unmixed zone was formed along the melting line in the substrate and first layer's interface, that whit increased laser power, area of this zone decreased, 7.27 to almost 0 (µm). As the layers approach the surface, the grains become unidirectional and coaxial growth. Increasing the laser power increased the average grain size of the layers.