The extended ductile fracture criterion of Al-Cu-Li alloy considering the influence of stress state and dynamic recrystallization

In engineering applications, precise prediction of fracture initiation is critical. While multiple ductile fracture criteria exist for this purpose, the interplay between fracture and microstructural evolution remains underexplored, especially in elevated temperature deformation, both temperature and strain rate lead to changes in microstructure and affect fracture. Based on microvoid nucleation and deformation mechanisms, a ductile fracture criterion was established. An extension of this criterion to elevated deformation scenarios was developed by integrating the correlation between fracture strain (ef) and dynamic recrystallization (DRX). Initially, the deformation of single microvoid under varying stress states was explored, characterized as either microvoid dilation or microvoid elongation/rotation. A three-dimensional surface of {r(, L, ef} was constructed through least-square fitting, providing insights into how stress state modulated ductile fracture. Subsequently, elevated temperature experiments of Al-Cu-Li alloy were conducted to elucidate the influence of DRX on ef. Z parameter served as an indicator was introduced to characterize the combined impact of T and e(center dot) on DRX. The results showed that when DRX occurred, ef decreased with the increase of Z parameter. In contrast, ef remained unaffected by Z parameter in the absence of DRX. The extended fracture criterion was established by linking Z parameter and stress-state-dependent ductile fractures. Finally, the extended fracture criterion was validated through experiments and simulation. The proposed extended ductile fracture criterion provides a contribution for optimizing elevated working processes by analyzing fracture initiation tendencies.