Study On Damage And Fracture Behavior And Modeling Analysis During Thermal Deformation Processing Of 2024 Aluminum Alloy Sheet

As one of common defects in sheet metal forming, fracture will cause the decline of product rate and material waste. The damage and fracture process of metal is caused by internal micro-defect constantly evoluting and developing, and eventually these microdefects form the macroscopic crack. The research on damage evolution mechanism and fracture behavior can be conducive to obtain forming limits of metal materials under different deformation conditions, and it will save time for the design and optimization of forming process parameters. Aimed at 2024 aluminum alloy sheet and using the methods of mechanical properties test and SEM observation, this paper studied the rheological behavior and damage mechanism of material under the condition of room temperature and high temperature, and based on experiments and numerical simulation, a kind of 2024 aluminum alloy damage finite element model was established.Firstly, based on the uniaxial tensile tests of 2024 aluminum alloy plate at room temperature and 300 ? ~520 ? high temperatures, this paper analyzed the rheological behavior and fracture behavior of sheet under different temperatures. The results show that when the temperature is below 495?, along with the temperature increase the plasticity will be improved, but when the temperature is higher than 495?, with the temperature rise the plasticity gradually get deteriorated. The fracture morphology of crack is markedly different.SEM was used to observe the fracture morphology as well as the microstructure near the fracture samples. And the damage mechanism was summarized at different temperatures. The studies have shown that the damage mechanism will change from dimple fracture to intergranular fracture along with the temperature rise. This phenomenon is related to the composition and mechanical properties of inclusion inside the alloy.Using ABAQUS finite element software to build a model for the uniaxial tensile process of 2024 aluminum alloy, then introduced the Johnson-Cook damage model into the uniaxial tensile finite element model of 2024 aluminum alloy based on the experimental data and finite element numerical analysis results. Ultimately a 2024 aluminum alloy failure model wad completed and it has been verified that the simulation results of the 2024 aluminum alloy failure model is relatively correct compared with the test results.Using the 2024 aluminum alloy failure model to forecast the damage and fracture phenomenon of rectangular box in hot deep drawing process. Then the reliability and accuracy of the failure model was verified by comparing the simulation results with test results. The comparison results show that there is an ideal forecast effect of the 2024 aluminum alloy failure model when used to predict damage evolution and crack growth trend in complex plate forming process.