Microstructure and Tensile Properties of Laser Metal Deposited RepairedK447A Superalloy

K447A superalloy substrates were successfully repaired by laser metal deposition . The microstructure, elemental distribution, phase constitution and tensile properties of the substrate and repaired region were systematically investigated using optical microscopy, scanning electron microscopy, energy dispersive spectroscopy and tensile tests, providing theoretical support for the application of superalloy repair. The results show that the repaired region of K447A superalloy exhibits a typical cellular–dendritic γ matrix microstructure, with fine γ′ precipitates uniformly distributed within the dendrites, while a certain degree of elemental segregation is observed in the interdendritic regions. The tensile strength of specimen 1 reaches 586 MPa, which is significantly higher than those of specimens 2 and 3, whereas the yield strengths of the three specimens are relatively close. Tensile fracture mainly occurs in the fusion zone of the repaired region, and the fracture surfaces present typical ductile fracture characteristics. In contrast, the fracture location of specimen 3 shifts to the pore-containing region due to defects such as pores, resulting in a significant reduction in mechanical properties.