Strain path change effects on stretch formability of 6082 aluminium alloy

Abstract

The effect of uniaxial prestraining on the stretch forming of 6082 aluminium alloy in different heat treated conditions has been investigated. Two effects were significant. First, the change in strain path between the prestraining and stretch forming stages affected the strain hardening behaviour, and this depended on the heat treated condition. Second, inhomogeneous deformation associated with the Portevin–LeChatelier effect in solution treated and, to a lesser extent, naturally aged material led to thickness inhomogeneities which promoted failure in stretch forming. Both of these effects are directional, and combine with an inherent inhomogeneity in the initial sheet material in inducing failure. The strain hardening effect had a more general effect on strain distribution, whereas both the initial inhomogeneity and any inhomogeneity induced by prestraining principally affected limit strains.