Numerical and Experimental Analysis of Residual Stresses and Distortion In Different Quenching Processes of Aluminum Alloy Profiles

Age hardening is the most important heat treatment for aluminum alloys to increase their strength. It consists of solution annealing, quenching and aging. The finite element method (FEM) has become a very efficient tool in understanding and evaluating of thermal stresses and distortion during heat treatment and is commonly used to improve the heat treatment of steels. In contrast, only few simulations focused on age hardening of aluminum alloys exist. Therefore, an engineering-based method for the numerical determination of residual stresses and distortion of aluminum alloy components due to quenching has been developed. Reliable numerical simulations require accurate material properties and realistic constitutive laws. Quenching simulation of aluminum alloys requires the material behavior of undercooled states subject to temperature and microstructure. Therefore, tension / compression tests of the undercooled aluminum alloy 6082 have been performed in a quenching and deformation dilatometer. Samples have been solution annealed and quenched in the dilatometer to varying temperatures with varying cooling rates. Immediately after quenching, uniaxial load tests on quenching temperature have been performed in the dilatometer. The results have been implemented in a combined isotropic-kinematic hardening model of the FEM-Software SYSWELD. Quenching of an extruded 6082 L-profile in water and in a gas nozzle field has been simulated in order to calculate distortion and residual stresses. The numerical investigations are accompanied by quenching experiments of L-profiles. The temperature curves over time and the final state of stresses and distortion have been analyzed. These experimental results verified the thermal and mechanical simulation results.