Anisotropic tensile properties of GH4169 alloy repaired by laser direct energy deposition

The tensile properties of GH4169 superalloy repaired by direct energy deposition are anisotropic, and there is a significant correlation between the tensile properties and the angle between the stress direction and the repair interface (interface angle). Studying the tensile anisotropy of the repaired alloy can lay the foundation for high-performance repair of GH4169 superalloy components. Based on Digital Image Correlation (DIC) technology, this study conducts tensile tests and mechanical behavior analysis of the repaired alloy at different interface angles, and combines Optical Microscopy (OM), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS) and other methods to observe the microstructure and fracture morphology of the interface area. The anisotropic tensile mechanical properties of GH4169 alloy repaired by direct energy deposition were studied. The results indicate that the tensile properties of the repaired alloy exhibit a negative correlation with the angle between the tensile direction and dendrite growth direction; the fracture of tensile specimens is mainly caused by the separation of Laves/γ phase interface under tensile load, leading to crack nucleation and propagation. When the angle between dendrite orientation and tensile load is small, the larger irregular Laves phase between the dendrites breaks into small particles and moves along with the matrix γ phase, after fracture the dimples are deeper and the tensile strength and yield strength are higher; when the included angle is large, the delamination of Laves/γ phase interface between dendrites leads to crack nucleation, which then rapidly expands, and the fracture surface presents a large number of stepped dendritic intergranular fracture morphology, resulting in poor tensile performance. This study elucidates the mechanism of the influence of different stretching directions on the tensile properties of the repaired alloy, providing a basis for the comprehensive evaluation of the tensile properties of GH4169 superalloy components repaired by direct energy deposition.