Measuring the temperature dependence of the flow surface of magnesium alloy sheet

The present study attempts at characterizing the anisotropic behavior of the Mg AZ31B sheet alloy and constructing a flow surface using minimum possible experimental data. Uni-axial tests in compression and tension were conducted at room temperature and at elevated temperatures to measure the strain anisotropy at various strain levels. The true-stress true-strain curves at room temperature show that the material is soft during in-plane compression and then strain hardens rapidly at epsilon > 0.05. The compression in Normal direction is observed to be the typical parabolic hardening curve. With an increase in temperature, the steep hardening in the RD and TD compression, is observed to decrease and finally vanishes at T similar to 150 degrees C even though the strain anisotropy is significant at this temperature. The flow stresses at different strains were used to construct flow surfaces, at different temperatures. Finally, a visco-plastic self-consistent approach was used to model the deformation behavior and simulate a polycrystal yield surface at room temperature. The model was fit using the RD tensile flow stress and strain anisotropy.