Abstract:The dynamic tensile behavior of twin-roll cast-rolled and hot-rolled AZ31B magnesium alloy was characterized over strain rates ranging from 0.001 to 375 s^-1 at room temperature using an elaborate dynamic tensile testing method, and the relationship between its mechanical properties and microstructures. It is observed that the sheet has a strong initial basal fiber texture and mechanical twinning becomes prevalent to accommodate the high-rate deformation. The yield strength and ultimate tensile strength monotonically increase with increasing the strain rate, while the strain hardening exponent proportionally decreases with increasing the strain rate due to twinning-induced softening. The total elongation at fracture distinctly decreases as the strain rate increases under quasi-static tension, while the effect of strain rate on the total elongation is not distinct under dynamic tension. Fractographic analysis using a scanning electron microscope reveals that the fracture is a mixed mode of ductile and brittle fracture.

Key words: magnesium alloy; twin-roll casting; dynamic tensile; strain-rate sensitivity; fractography