Texture gradient evolution in Al-5%Ca-5%Zn sheet alloy after tensile deformation at high superplastic strain rate

Abstract

Texture inhomogeneities have been found in many materials. Given the significant influence of texture in industrial processes like superplastic forming of complex-shaped components, it is important to study the evolution of texture gradients under different testing conditions, particularly at high strain rates. Strong through-thickness texture-gradients have been observed in hot rolled Al alloys. As a consequence of the severe deformation during the hot rolling process, a well defined Brass texture-component (B-orientation) {l_brace}011{r_brace} develops in the mid layer. The Al-5%Ca-5%Zn sheet alloy deforms superplastically when tested uniaxially at temperatures ranging from 350 to 450 C and at strain rates between 10{sup {minus}5}s{sup {minus}1} and 10{sup {minus}2}s{sup {minus}1}. The B-orientation, however, is not present in the texture of the as-rolled material, but it appears after straining in tension along the transverse direction under certain conditions of temperature and moderately high superplastic strain rates. In this work the evolution of the through-thickness texture-gradient in the Al-5%Ca-5% Zn sheet alloy when tested uniaxially in the transverse direction is investigated. Due to the importance of high strain rates in superplastic forming processes, tests at higher strain rates than those usually reported in the literature have been conducted. Current models which predict the appearance of themore » B-component are criticized on the light of these new findings.« less