Repairing High γ' Hot Section Gas Turbine Components Using Advanced Manufacturing

This article describes the ability to use laser blown powder deposition to repair high gamma' IN -100 superalloy gas turbine components. The influence of various process conditions on the ability to make crack-free IN -100 deposits over surrogate high y' alloys was investigated to identify cracking mechanisms in the deposit and heat-affected zones (HAZs). The various crack formation mechanisms, such as solidification cracking and liquation cracking, were evaluated using multiscale characterization and numerical simulation. The cracking in the deposit region was predominantly solidification cracking, while those observed in the HAZ were liquation cracking. The results showed that controlling thermally induced residual stresses is the key to eliminating cracking, and the optimum preheat temperature was determined. The results were then contrasted with those in published literature and an approach to effectively repair hot section parts was presented.