Development of laser cladding repair process for first stage blading of high-pressure turbine for DR-59L gas turbine engine

BACKGROUND: A state-of-the-art aircraft gas turbine engine is an advanced technology consisting of a compressor, combustion chamber, turbine, nozzle, and other components. It includes the axial compressor with multistage rotor and stator blades important for the reliable operation of the gas turbine engine. All these components are subject to static, dynamic, and cyclic loads causing fatigue cracking, thermally induced stress, and mechanical damage. To increase the service life of gas turbine engines and reduce maintenance costs, technologies are used to restore worn or damaged moving blade surfaces. AIM: To restore worn surfaces of moving blades of DR-59L high-pressure turbine by laser cladding. MATERIALS AND METHODS: Prior to repairing the blades, we tested a range of laser cladding parameters on a check test piece to determine a defect-free structure. Stellite-21 cobalt alloy powder was used as a filler. To evaluate the structure and mechanical properties of the claded test pieces, we conducted metallographic studies and mechanical tests. RESULTS: By modeling the blade airfoil restoration process, we determined the operational conditions of the laser cladding process. No defects were detected during the capillary test of the restored surfaces. The uniaxial tensile test of the restored blade airfoil showed increased tensile strength and elongation. CONCLUSIONS: Laser cladding technology allowed to restore the worn surfaces of moving blades of DR-59L high-pressure turbine; thereby increasing the service life of the engine unit.