Effects of Strain Rate and Temperature on Tensile Flow Behavior and Energy Absorption of Extruded Magnesium AM30 Alloy

The effects of strain rate, temperature and texture on tensile flow stresses, and energy absorption of a magnesium extrusion AM30 alloy were experimentally determined over a range of strain rates (0.00075 and 9 s⁻¹) and temperatures (−143 and 100 °C). The extrusion has a texture such that the normals of the basal planes {0002} are approximately parallel to TD and the$<11\overline{2}0>$ crystal orientation is parallel to ED (ED = extrusion direction, TD = long transverse direction, and ND = short transverse direction of the extrusion). Tensile strain along the ED was accompanied by only limited twinning before necking. The yield strengths of ED samples depend linearly on a rate parameter commonly used for thermally activated deformation. Thermal activation analysis indicates that the activation volume is essentially constant. Tensile deformation in the long transverse direction (TD) showed significant twinning during the initial 6-8% strain. The ductility is good, with average total elongations at 22 °C and a quasi-static rate of 12.3 and 19.1% in ED and TD directions, respectively. Nominal strain energy densities were evaluated up to 10% engineering strain and to fracture. The crashworthiness of the Mg extrusion, taking into account yield strength, ductility, and density, compares favorably to automotive Al alloys and high-strength steels.