Residual Stress Characterization and Microstructure Evolution Analysis of Additively Manufactured IN718 Superalloy

At present, the research on the overall residual stress of additively manufactured superalloy components still faces challenges. This study systematically investigates the influence of annealing temperature on the evolution behavior of residual stress in IN718 superalloy fabricated via selective laser melting using X‐ray diffraction and the contour method, and analyzes the mechanism of residual stress relief in combination with microstructure characterization. The results indicate that there is significant tensile stress on the surface of the as‐built sample, and the longitudinal stress ( σ z ) is higher than the transverse stress ( σ x ). Internal stress primarily consists of compressive residual stress. However, after annealing treatment, most residual stress is alleviated through static recovery and recrystallization. Under medium‐low temperature (550–750 °C) annealing, recrystallization does not occur and the recovery capacity is relatively weak; thus, residual stress is partially relieved, reaching 20% and 50% respectively. Under high‐temperature (950–1150 °C) annealing, residual stress is significantly reduced, up to 90%. Especially at 1150 °C, dislocation is almost completely annihilated, recrystallization is mostly completed, and residual stress is nearly eliminated, approaching 0 MPa. The results provide technical support for the annealing process to eliminate residual stress in the superalloy.