Quenching Medium Quenching Residual Stress Of 7075 Aluminum Alloy Thick Plates

Precipitation-hardened Aluminium alloy 7075 is an Al-Zn-Mg-Cu alloy widely used in the aerospace industry. It gains its high strength through heat treatment involving a severe quenching operation, which can have the adverse effect of introducing residual stresses. It may become unstable with shape and dimension after mechanized process, owing to the releasing of residual stresses. So it is important to study the aspects which affect on residual stresses during the course of quenching. The effects of different quenchants on residual stresses in quenched Aluminium alloy 7075 thick-plates have been studied by measureing the residual stresses by drilling hole method in quenched 7075 thick-plates ; the principle of concentration and temperature of quenchants on residual stress in quenched 7075 thick plates have also been studied by using cooling curve of quenchants. The research have shown that residual stresses in quenched Aluminium alloy 7075 thick plates can been reduced considerablely by using proper quenchants such as AQ251,and controling the quenchant's concentration and temperature,you can get much lower residual stress in the quenched 7075 thick plates.The finite element software DEFORM is used to calculated the convection coefficient curves during the quenching of Aluminum alloy 7075 under different quenching processes. We have got the convection coefficients curves under different quenching processes by the software DEFORM-2D. The simulations show that the calculated convection cofficient during the different quenching processes are consistent with the true quenching processes and it can be used to calculate the residual stress during the course of quenching.