Refurbishing Inconel 738 Blades in GE-Frame5 Gas Turbines Through Laser Cladding and Welding

This study investigates the refurbishment of first-stage Inconel 738 blades for GE-Frame 5 gas turbines using laser cladding and welding techniques. Laser welding was performed with a pulsed Nd:YAG system equipped with a manual 0.7 mm Inconel 625 filler wire feed. In contrast, laser cladding utilized a continuous fiber laser paired with an automated powder injection system for Inconel 625. Process parameters, including scanning speed, laser power output, and powder feeding rate, were optimized to enhance the laser cladding. Testing showed that laser settings of 400 W power, 15 g/s powder feed, and 8 mm/s scanning speed produced coatings with superior geometry, completely eliminated hot cracking, and minimized porosity. Preliminary weld tests identified optimal settings of 4 mm/s scanning speed at 5 kW maximum power. Subsequently, 20 layers were deposited to simulate worn blade tip repair welds. Both methods effectively reduced heat-affected zones through refined parameters. Pulsed laser welding with filler material broadened repair options for gas turbine blades. However, the surface hardness in treated areas was somewhat lower than that of the base material due to phase transformations occurring during laser cladding and welding.