7075 Aluminum Alloy Plate Residual Stress In Quenched

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 residual stresses. The principles of affecting on residual stresses in quenched Aluminium alloy 7075 thick-plates have been studied and concluded under different thermal treatments and different pre-stretching techniques by the drilling method. The tests show that residual stresses have converted from compress-stresses to tension-stresses with the development of degrees of pre-stretching, and have basically got zero near two percents; It also has indicated that residual stresses have both been reduced in the directions of rolling and transverse with the development of aging temperatures and times. By raising the quenched-media' s temperature, residual stresses were reduced distinctly.The finite element method is used to simulate the quenching of Aluminum alloy 7075 in an attempt to predict the distribution that develops in simple shapes. We have got several distributing graphs under different quenched-media' s temperature and 2. 5 percents of pre-stretching. The results are receivable. In the same time, the active propulsions of reducing quenched residual stresses after raising the quenched-media' s temperature have been certified as the same as the results showed by the finite element method simulation.The studies show that they are effective measures to reduce residual stress in quenched Aluminium alloy 7075 by taking appropriate pre-stretching, aging treatment and the quenched-media' s temperature, especially well by adaptable pre-stretch .