Superplastic properties of Pb–62%Sn eutectic alloy after equal channel angular pressing (ECAP)

Billets of Pb–62%Sn alloy were subjected to equal channel angular pressing up to various numbers of pressings of 1, 4, 8 and 16 passes via route BC at room temperature in order to investigate its superplastic properties. These samples were pulled to failure in an Instron machine at a temperature of 413 K at initial strain rates ranging from 1.0 × 10−3 s−1 to 2.0 × 10−2 s−1. The initial grain size was ∼14 μm and the grain sizes corresponding to 1, 4 and 8 passes were 10.7, 9.2 and 8.4 μm, respectively. At a strain rate of 1.0 × 10−3 s−1, which is rather close to the optimum superplastic region II in this material, for 8 passes the elongation to failure increased from 2330 to 3000%, which can be considered to be optimum number of pass for attaining highest ductility.