Investigation of hot workability behavior of as-cast Mg–5Sn–2Ca (TX52) magnesium alloy through processing map

Abstract

The hot deformation behavior of TX52 has been studied with a processing map developed on the basis of its temperature and strain rate dependence of flow stress. The map exhibits two domains of dynamic recrystallization in the ranges of (1) 300–410 °C/0.0003–0.003 s−1 and (2) 440–550 °C/0.02–10 s−1. Kinetic analysis gives apparent activation energy values of 191 and 198 kJ/mol in Domains 1 and 2, respectively. These values are higher than self-diffusion in Mg signifying that substantial back stress is being generated due to the large volume fraction of intermetallic particles in the matrix. In Domain 1, basal + prismatic slip occurs with recovery by climb, while at higher temperatures (Domain 2) second-order pyramidal slip occurs with simultaneous softening by cross-slip. Domain 2 is recommended for maximizing workability and Domain 1 for finishing steps to achieve finer grain size in the final product.