Microstructure evolution of internal defect healing zone in ZTC4 titanium alloy during hot isostatic pressing

The internal displacement change around shrinkage pores, stress and strain distribution, and microstructural evolution in the defect healing zone of ZTC4 titanium alloy during hot isostatic pressing (HIP) are investigated by numerical simulation combined with experimental methods. The results demonstrate that under the high-temperature and high-pressure conditions of HIP, high stress-strain zones form around the shrinkage pores. The stress magnitude shows an inverse relationship with the distance from pore surfaces, exhibiting higher stress levels in proximity to the pore boundaries. As the shrinkage pore size decreases, the strain concentration intensifies. After HIP, a radial pore-healing zone microstructure develops at the original shrinkage pore sites. Within this healed region, heterogeneous plastic deformation occurs among distinct α/β colonies. Colonies with more readily activated dislocation slip systems experience greater deformation magnitudes, ultimately leading to the formation of equiaxed grain structures.