A novel constitutive model for two-stage creep aging process of 7B50 aluminum alloy and its application in springback prediction
(1. AVIC General Huanan Aircraft Industry Co., Ltd., Zhuhai 519000, China;
2. State Key Laboratory of Precision Manufacturing for Extreme Service Performance, Central South University, Changsha 410083, China;
3. Light Alloy Research Institute, Central South University, Changsha 410083, China;
4. Beijing Institute of Astronautical Systems Engineering, Beijing 100076, China)
2. State Key Laboratory of Precision Manufacturing for Extreme Service Performance, Central South University, Changsha 410083, China;
3. Light Alloy Research Institute, Central South University, Changsha 410083, China;
4. Beijing Institute of Astronautical Systems Engineering, Beijing 100076, China)
Abstract: A new unified constitutive model was developed to predict the two-stage creep-aging (TSCA) behavior of Al-Zn-Mg-Cu alloys. The particular bimodal precipitation feature was analyzed and modeled by considering the primary micro-variables evolution at different temperatures and their interaction. The dislocation density was incorporated into the model to capture the effect of creep deformation on precipitation. Quantitative transmission electron microscopy and experimental data obtained from a previous study were used to calibrate the model. Subsequently, the developed constitutive model was implemented in the finite element (FE) software ABAQUS via the user subroutines for TSCA process simulation and the springback prediction of an integral panel. A TSCA test was performed. The result shows that the maximum radius deviation between the formed plate and the simulation results is less than 0.4 mm, thus validating the effectiveness of the developed constitutive model and FE model.
Key words: two-stage creep aging process; bimodal precipitation; constitutive modeling; springback prediction; Al-Zn-Mg-Cu alloy