Influence of laser shock peening on the joint surface strength of laser cladding repair of GH4169 superalloy component

Abstract

Laser cladding is an effective method to repair damaged aeroengine blades. However, the heat affected zone of laser cladding reduces the strength of the repaired component. A solution method that strengthening the joint surface by laser shock peening (LSP) before laser cladding was proposed. The process parameters of LSP, such as energy, spot size, overlap ratio, spot path, etc., were determined based on the theoretical analysis; and the specimens were prepared by laser cladding after LSP. The influence of LSP on the strength, hardness and microstructure of the repaired specimens of GH4169 superalloy were researched based on the axial tensile test, metallographic test and hardness test. The results show that the tensile fracture of the specimens which only treated by laser cladding appears on the joint surface; however, the tensile fracture of the specimens treated by both of LSP and laser cladding does not necessarily appear on the joint surface, which indicates that the LSP can effectively improve the strength of the joint surface. The tensile strength of the specimen treated by both of LSP and laser cladding increased by 52.3%, and the elongation of the specimen increased from 0.8% to 9.2%. The metallographic observation showed that the grains of the specimens treated by LSP were refined obviously, and the grain size decreases by 36.5%, which is beneficial improve the strength of the joint surface. The microhardness of the specimen was more uniform and the maximum difference between the two sides of the joint surface decreased by 19.4% when the LSP was added in the repairing process.