Time-dependent uniaxial behavior of rolled magnesium alloy AZ31B at 393 K and room temperature

To address the time-dependent properties of rolled AZ31B alloy, we conducted typical tests of the rate jump, creep, and stress relaxation at room temperature and 393 K. In the rate jump tests, the tensile curve exhibited a strong dependence on the strain rate, whereas compression was totally insensitive to the stress rate at both temperatures. For the creep and stress relaxation test, we observed creep strain and decay stress in the compression, which was weaker than the tensile curve. The plastic viscosity increased at 393 K because the dislocation motion was thermally activated. We then applied thermal activation theory for the repeated stress relaxation tests. The activation volume implies that cross-slip and dislocation nucleation are the operating mechanisms for creep and stress relaxation.