Hot workability characteristics of cast and homogenized Mg–3Sn–1Ca alloy

Abstract

Hot working behavior of Mg–3Sn–1Ca alloy has been evaluated with a view to explore its potential as a wrought alloy. The temperature and strain rate dependence of steady state flow stress has been analyzed. The processing maps exhibited two domains both in the temperature range 350–550 °C with one in the lower strain rate range (0.0003–0.01 s−1) and the other at higher strain rates (1–10 s−1). The apparent activation energies estimated in these two domains respectively are 217 kJ/mole and 154 kJ/mole. The activation area values obtained, after making a correction for the back-stress generated by the hard intermetallic CaMgSn particles, are in the range 13–100 b2 and decreased with increasing effective stress. The corrected results suggest that the lower strain rate domain is controlled by lattice self-diffusion and grain boundary diffusion occurs at higher strain rates. Extrusion at 500 °C and at a speed that corresponds to an average strain rate of 3 s−1 yielded a sound product with a dynamically recrystallized microstructure.