Effect of pre-strain on creep aging behavior of 2524 aluminum alloy

As an advanced manufacturing technology, creep age forming (CAF) has been developed to form large aluminum panels. However, industrial processes often involve complex thermo-mechanical treatments. For instance, it is necessary to impose a plastic strain after solution heat treatment to relieve quench stresses. In this work, the effect of tensile pre-strain before CAF on creep aging behavior of 2524 aluminum alloy is investigated by constant-stress creep aging test, Transmission Electron Microscope (TEM) and mechanical properties test. It is found that the magnitude of creep strain is greatly increased with the increase of pre-strain. Moreover, the peak strength of the creep aged AA2524 is enhanced and the time to reach the peak strength is decreased with the increases of pre-strain. TEM observations revealed that the precipitation process of AA2524 is accelerated due to pre-strain treatment. With the increase of pre-strain, the average size of S (Al2CuMg) phases is reduced. Meanwhile, the density and homogeneity of S phases are improved. Thus, it can be concluded that the pre-strain can evidently improve the formability, mechanical properties and microstructures of AA2524 in creep age forming process.