Creep behavior of spray-cast 7XXX aluminum alloy

In response to the demands for improved mechanical properties, alloy and process developers have been exploring the possible addition of solute contents well beyond those used in conventional ingot metallurgy, as well as the incorporation of non-traditional solute additions, such as the transition metals. Techniques such as rapid solidification are necessary to ensure that damage-tolerant properties, such as toughness and crack growth, are not sacrificed at the expense of the transition metal elements, which have limited solubility and low diffusivity. In this study, we used the SS70 product, which is a new type of heat-treatable (AlZnMgCuZr) spray-cast aluminum alloy. Solution heat treatments were carried out on standard creep samples at 480°C for 1 h. After aging at 120°C and achieving the T6 condition, samples were creep-tested at variable stress from 200 to 360 MPa at 120°C. Creep rate results of the SS70 alloy show a much lower rate of creep in this material compared with the ingot-cast 7075 alloy.