γ′ Phase‐Informed Ductile Damage Modeling for GH738 Superalloy in Hot Deformation

To mitigate damage‐induced cracking in GH738 superalloy during hot deformation, the interplay between thermomechanical parameters (temperature, strain rate, stress triaxiality) and damage mechanisms is systematically investigated through integrated experimentation and multiscale modeling. High‐temperature notched tensile tests combined with fracture morphology analysis reveal three critical dependencies: elevated temperatures accelerate void coalescence via γ′ phase dissolution and reduced dislocation pinning; lower strain rates enhance void growth through stress relaxation; and decreased stress triaxiality promotes self‐constriction effects, refining dimple distribution while intensifying necking. A micromechanics‐enhanced Gurson–Tvergaard–Needleman (GTN) model incorporating γ′‐sensitive void‐growth suppression is developed, where dense γ′ distributions impede void growth via bypass‐dominated dislocation interactions. Finite element validation demonstrates excellent accuracy in predicting fracture behavior across diverse thermomechanical conditions. This γ′ phase‐informed damage framework enables precise control of void evolution during hot forging, providing a critical tool for optimizing process parameters to suppress damage in γ′‐strengthened superalloys.