Creep aging experiments reveal how temperature influences fracture behavior in 7050 aluminum alloy, indicating significant changes in material strength.
Creep age forming technology is a new method to realize the collaborative manufacturing of high performance and precise forming of large integral components. 7xxx aluminum alloy is widely used in the manufacturing field of aerospace key components due to its excellent properties of high strength, low density and fatigue resistance. The creep aging fracture behavior, age hardening response and microstructural evolution of 7050 aluminum alloy under different process parameters (creep temperature and stress) have been systematically studied by creep aging experiment, mechanical property test, metallographic microscopy, scanning electron microscopy and damage constitutive model. The results indicate that as the creep temperature increases, the stress level at which fracture occurs significantly decreases, and the sensitivity of creep fracture behavior to stress levels increases. Under various combinations of creep temperature and stress, the material exhibits a creep fracture window, enabling the construction of a creep aging forming limit diagram. Microstructure observations of the creep fracture process reveal that elevated temperatures activate additional slip systems, thereby accelerating creep deformation. This also leads to the formation of more micro-voids along grain boundaries. These micro-voids serve as potential sites for crack initiation, growing progressively within slip regions during deformation, and reducing the critical stress required for creep fracture. Based on the Continuum Damage Mechanics (CDM) model, a damage constitutive model for creep aging fracture in 7050 aluminum alloy considering the effects of precipitates on mechanical properties and creep damage variable was established. Numerical solutions and finite element simulation analysis of specimen-scale creep aging fracture behavior validate the accuracy and applicability of the proposed constitutive model for 7050 aluminum alloy.
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Ren et al. (2025) studied this question.