Effect Of Deformation Temperature On Mechanical Properties And Corrosion Resistance Of 7A04 Aluminum Alloy With ECAP

7A04 aluminum alloy has the advantages of high strength and obvious heat treatment strengthening effect,and has become a super-hard aluminum alloy widely used at present.In this paper,the problem of insufficient corrosion resistance of the aluminum alloy during use is studied.In this paper,the deformation behavior of 7A04 aluminum alloy with equal channel angular deformation at different temperatures was studied by means of electrochemical workstation,transmission electron microscope and X-ray diffractometer.The mechanical properties and corrosion resistance were obtained.The influence of the deformed structure on the corrosion mechanism was analyzed and explored.The main conclusions of the following points are obtained:1.The optimized process of 7A04 aluminum alloy in this study is:solid solution（470°C/4h）→quenching（25°C water quenching）→equal channel angular deformation four times（at 120°C deformation temperature）can obtain better mechanical properties And corrosion resistance.2.The tensile strength of the 120°C-4p sample obtained by the optimized process was19.1%lower than the original sample and 483.7 MPa,but the corrosion resistance was better than the original sample.In the potentiodynamic polarization test,the corrosion current density was reduced by 19.4%to only 2.9E-5 A/cm².In the electrical impedance test,the radius of the arc resistance increased by 22.8%to 2517.6Ω·cm².At the same time,the intergranular corrosion grade in the intergranular corrosion test was increased from 4 to 2,and the maximum corrosion depth was reduced by 79.6%to only 25.4μm.3.At the deformation temperature of 120°C,the equal-diameter angular deformation increases the dislocation density of the alloy by introducing the strain amount to obtain a large number of sub-crystals,which destroys the continuity of precipitation of the precipitated phaseη（MgZn₂）along the grain boundary,so that the precipitated phase is dispersed;the four-pass deformation can refine the average size of the precipitated phase to 30 nm,thereby improving the corrosion resistance of the alloy.4.At a deformation temperature of 400°C,the precipitated phaseη（MgZn₂）in the alloy is largely precipitated and coarsened.The average precipitated phase size was 1.0μm in one pass,1.3μm in four passes,and 1.7μm in eight passes.That is,as the amount of deformation increases,the precipitation phase continues to grow,resulting in a decrease in the mechanical properties and corrosion properties of the alloy as the amount of deformation increases.