Strain Rate and Temperature Effects on Formability and Microstructure of AZ31B Magnesium Alloy Sheet

Abstract

Magnesium alloys play an important role in lightweight structures, which are extensively used in different industries due to their excellent mechanical and physical properties. In this paper, the formability of the AZ31B magnesium alloy sheet was studied by using tensile tests at different temperatures (from 25 to 250◦C) and strain rates (from 0.017 s−1 to 0.34 s−1). The results showed that the material behaves with positive temperature sensitivity when forming at a temperature lower than 200◦C. The effect of the strain rates on the formability of AZ31B was larger at high temperatures. The metallography of AZ31B at different temperatures and strain rates was observed by OM. The results showed that the partially recrystallized structure was exhibited at a temperature of 150◦C. With the increase in temperature, the approximate complete recrystallization was exhibited at a temperature of 250◦C. The fracture morphology of AZ31B was observed at different strain rates and temperatures by SEM. Additionally, the main fracture pattern was quasi-cleavage at room temperature. However, with the increase in temperature, the fracture pattern was transited from a quasi-cleavage pattern to a ductile fracture pattern. The ductile fracture pattern was the main fracture pattern at a temperature of 250◦C.