Distribution of microstructure, elastic modulus and residual stress near the interface in laser repaired GH4169 superalloy

As an emerging additive manufacturing technology, Direct Energy Deposition (DED) shows great potential for repairing or remanufacturing high-value components, such as aero-engine turbine blades. Through the utilization of Direct Laser Deposition (DLD), a specific form of DED, GH4169 superalloy powder can be cladded onto a GH4169 substrate to mimic the repairing of aerospace components. The microstructure, mechanical properties, and their distribution characteristics near the interface under different DLD process parameters are comprehensively studied. Combining Electron Backscatter Diffraction (EBSD), data stitching technique, and first-principles, the grain orientation and the elastic stiffness matrix of each phase are determined, based on which the distribution of elastic modulus and residual stress in a relatively large and complex area are analyzed. The results indicate that the DLD process parameters, such as linear energy density, significantly affect the grain size, grain growth direction and residual stress, but much less on the elastic modulus. Furthermore, the microstructure presents significant nonuniformity near the interface, and the elastic modulus presents anisotropy at the microscale, but almost isotropy at the macroscale, without noticeable value differences among the cladding zone, the heat-affected zone (HAZ) and the substrate. This study could shed light on the DLD process optimization for improving the microstructure and mechanical properties of laser-repaired components.