Tensile properties and a modified s-Johnson-Cook model for constitutive relationship of AA7075 sheets at cryogenic temperatures

This study investigated the cryogenic uniaxial tensile behaviors of AA7075 at various deformation temperatures (77 K∼298 K) and strain rates (10–4 s–1∼10–2 s–1). And then the effects of deformation temperature and strain rate on the rheological law of AA7075 in a cryogenic environment were studied. A modified s-Johnson-Cook constitutive model, incorporating a strain compensation coefficient, was developed using the true stress-strain curve of AA7075, and it was found to match well with experimental results. The study also analyzed the effect of the cryogenic environment on the mechanical properties of AA7075 by examining the fracture morphology and microstructure. In addition, it was observed that the modified s-Johnson-Cook constitutive model can also be applied to AA6060 and AA2060-T4 alloys under a cryogenic environment with an error rate of less than 0.8%, which may aid in the advancement of cryoforming techniques for aluminum alloys in the future.