Feasibility of laser cladding for tooling repair in aerospace manufacturing: an alternative to chrome plating

Advanced remanufacturing by additive manufacturing is challenging in aerospace due to the minimization of material costs, preparation times and metal waste. This study analyzed a 40HM low-alloy steel ring as a demo tooling used to produce aircraft engine components. The possibility of using laser cladding with powder process with the additive material NiCrBSi alloy powder was analyzed. Optimal parameters of the process were selected in terms of the assumed structural requirements (geometrical parameters of the clad, its hardness and the size of the heat-affected zone) for the remanufactured surfaces, ultimately obtaining a crack-free multilayer coating with a thickness of 2 mm and a hardness of above 700 HV1. The remanufacturing process was performed on three representative surfaces: flat face, cylindrical external, and internal. This approach allowed an analysis of the possibilities of finishing the laser-deposited layers with the machining methods used in the actual tooling department of the aerospace company: turning, milling, grinding, and center grinding. During chip processing, the defects (holes, cracks) made machining difficult and ineffective, mainly due to accelerated tool wear. Single cracks were observed after the grinding operation, which may reduce the durability of the remanufacturing layer. Both the changes in the microstructure of the demo component and the phases present in the cladding were analyzed. The deposition process was found to form a martensitic structure in the substrate at the cross-section in proximity to the remanufactured surfaces. This was also confirmed by an increase in average hardness from 402 HV1 to 605 HV1 for the analyzed substrate areas.