Effect of heat treatment and electromagnetic forming on springback and properties of 7075 aluminum alloy sheet

Abstract

7075 aluminum alloy is widely used in aerospace-related applications due to its high specific strength and good corrosion resistance; however, it is difficult to deform 7075 aluminum alloy at room temperature. In this paper, we investigate the mechanical and corrosion properties and springback characteristics of 7075 aluminum alloy after electromagnetic forming and heat treatment. The 7075 aluminum alloy subject to different pre-natural aging conditions was deformed via electromagnetically assisted stamping; the part was then subject to a second natural aging process. After a total natural aging time of 3 h, the parts were artificially aging at 120°C. It was found that the peak time of artificial aging (18 h) was not affected by the various pre-natural aging procedures and electromagnetic forming. The intergranular corrosion depths were found to be 92.6 and 5.4 µm for parts subject to peak artificial aging and retrogression and re-aging (RRA). This is because the grain boundary contains regions of continuous η phase and the cubic texture of the material is weak under peak aging. However, grain boundaries were found to exhibit discontinuous η phases, and the cubic texture of the material was enhanced after the RRA processing.