Study On Mechanical Properties And Microstructure Characteristics Of 7075 Aluminum Alloy After Age Forming

With the continuous improvement of modern aircraft performance and increasing weight requirements, single part manufacturing technology whose developing direction is whole structure manufacturing technology. Integral panel structure as the most important structural component of modern aircraft’s body and wings has been widely used these days.age-forming technology has a special advantage in integral panel structure production of aerospace vehicle as a new aluminum alloy forming process.This paper chooses 7075-T6 aluminum alloy as research subject which is widely usd as Integral panel structure of plane.By performing age forming with the different conditions to study the changes of spingback rates and mechanical properties after age forming.The microstructure after age forming were observed and analyzed by using a variety of micro-analysis tools(such as OM, XRD, SEM, TEM). And exploring the evolution of the microstructure of 7075 alumimum alloy after age forming and strengthening mechanisms.The results show:The spingback rates of 7075 alumimum alloy after age forming with a fixed time of 4h and rising temperature decreases. The spingback rates of 7075 alumimum alloy after age forming with a fixed temperature of 180 and rising time decreases in short ℃time,and finally it tends to an equilibrium value.XRD and EDS analysis show: the microstructure after age forming has GP zone, η’ plase(Mg2Zn) and η plase(Mg2Zn).And there is impurity phase with Fe,Si.With the age forming conditions of a fixed time of 4h and rising temperature: when the temperature is lower, a large number of GP zones andη’ plase dispersed in the crystal,and there is a continuous chain of fine precitates in the grain boundary. With the temperature increases, GP zones quickly dissolve, η’ plase density increases, the size become large, the strength,hardness and elongation have declined. As the temperature continues to rise, sheet η plase in the crystal increases. There are intermittently and thick precipitates appear in the grain boundary. And the strength, hardness and elongation of material decline rapidly.After age forming of a temperature of 180℃, as time increases the GP zones quickly dissolved and transformed into η’ phase. As time continude to rise, η’ phase gradually transformed into η plase and the size become thick.There result in rapid decline in strength and finally tends to balance. There is a discontinuous precipitates in the grain boundary and the size becomes lager.