Stress-strain response of textured AZ31B magnesium alloy under uniaxial tension at the different strain rates

Grain orientation and deformation strain rate have impact on mechanical behaviors of magnesium alloys through their effect on the deformation modes. In this paper, uniaxial tensile tests were conducted at room temperature under various strain rates, from 2.8×10−5 s−1 to 1.1×10−1 s−1, on two kinds of AZ31B magnesium alloy samples which possess fiber texture and spread texture, respectively. It was found that the flow stress-strain curves of the samples with the fiber texture show a concave down shape and a yielding stress higher than that of the samples with the spread texture. The samples with the spread texture present a linear shaped true stress-strain flow curve. A “quasi horizontal step” appears on the stress-strain curves at the high strain rates, related mainly to {10-12} tension twinning that becomes an important deformation mode of grains. It was believed that the difference of stress-strain responses between the two kinds of tensile samples results from the difference of the slip modes, the contribution of the slips to plastic strain decreases with the increment of strain rate.