7075 Aluminum Alloy Plate Residual Stress In Quenched Numerical Analysis

Aluminium alloy 7075 thick plate stretched with high strength and toughness and few residual stresses is a kind of structural material widely used in the modem aerospace industry. In order to get high strength,the alloy need be quenched.but a lot of residual stresses will be appeared during quenching. Not only shape and dimension will be unstable after mechanized process, but also synthetic performance will descend, owing to the releasing of residual stresses.So it is very important to know clearly residual stresses quenching how to form and develop.But it is pity that only residual stresses in surface layer can be tested by measure of existing instruments.With the development of modem numerical simulation technology,there is a better choice with Finite Element Method(FEM) to know clearly residual stresses quenching how to form and develop and konw size and distribution of residual stresses.All temperature and thermal stresses fields can be analyzed numerically within yield behave and vivid residual stress fields in the process of 7075 aluminum alloy thick plates quenching in water in virtue of the finite element program ANSYS, refer to convection coefficient curves that come from isothermal compression test at Gleeble-1500 thermal-mechanical simulator.Results in the paper are as follow:1. temperature increase according to nonlinear path along its thickness and ideal thermal stress decrease according to descending nonlinear path along its thickness.2. residual stress quenched are appearance between areas without plastic deformation and areas that Asymmetry plastic deformation quenching that thermal stress place a premium on.3. residual stress quenched how to distribute along its thickness and the relation between residual stress quenched and the situation hn in where there are no residual stress:there are press stress in surface and center of sample and there are pull stress between two press stresses, it is the reasonable technics to get few residual stresses when the temperature of AQ251 quenchen medium is 40癈 and when the concentration of AQ251 quenchen medium is 30%.4. the relation between quenching and dynamical vapor film or PAGfilm in AQ251 quenchen medium: the dynamical influence of expansion and shrinkage when temperature varing, plastic deformation, heat exchange, difference in temperature and dynamical vapor film and PAG film in AQ251 quenchen medium on thermal stress during quenching are revealed clearly in this paper.