Analysis of anisotropy of extruded magnesium alloy AZ31 bar

The large strain Elastic Visco-Plastic Self-Consistent (EVPSC) model, with the recently developed Twinning and De-Twinning (TDT) description, is applied to study the mechanical behavior of magnesium alloy AZ31 extrusion. Five different specimen orientations with tilt angles of α of 0°, 22.5°, 45°, 67.5° and 90° between extrusion direction and longitudinal specimen axis are used to study the mechanical anisotropy under both uniaxial tension and compression. It is found that the uniform strain under tension is sensitive to the tilt angle and the maximum uniform strain is found at α = 45°. The effect of pre-strain in uniaxial compression along the extrusion direction on subsequent uniaxial tension and compression along different directions with respect to the extrusion direction is also investigated. It is demonstrated that the influence of the twinning during pre-strain in compression and the detwinning in the subsequent uniaxial tension on the uniaxial tension response depends significantly on the tilt angle. By comparing the differences in the flow stress vs. orientation curves between the as-received and pre-strained samples, the effect of pre-straining on material anisotropy is investigated. It is found that the pre-compression lowers the uniform strain regardless of the tilt angle α.