Effect of hot rolling on the microstructure and mechanical properties of Mg–5Al–0.3Mn–2Nd alloy

Mg–5Al–0.3Mn–2Nd alloy was prepared by metal mould casting. The as-cast ingot was homogenized, and then hot-rolled with total thickness reduction of 63%. Further annealing treatment was carried out on the hot-rolled sample. Microstructure and mechanical properties of the studied alloy in as-cast, hot-rolled and annealed states were investigated. Results showed that main phases of the as-cast sample were composed of α-Mg, Al2Nd, Mg17Al12 and Al11Nd3. While for the hot-rolled and annealed samples, no Mg17Al12 phase was detected. Average grain size of the as-cast sample was about 90 μm. After hot rolling, average grain size was greatly refined to about 20 μm. Furthermore, the long acicular Al11Nd3 phase broke into many small sections. Tensile test results showed that ultimate tensile strength and yield strength of the hot-rolled sample were 340 MPa and 240 MPa, respectively. Compared with those of the as-cast sample, they were enhanced by 47.8% and 269% correspondingly. However, elongation greatly decreased to 9%. Through annealing treatment, elongation recovered to more than 24% again.

Research highlights▶ Hot rolling was carried out on Mg–5Al–0.3Mn–2Nd alloy. ▶ Basal texture was obtained for the hot-rolled sample. ▶ Grain size was refined and mechanical properties were enhanced by hot rolling. ▶ Hot-rolled alloy demonstrated good thermal stability.