Anisotropy of tensile properties of extruded magnesium alloy AZ31

The mechanical behaviour of wrought magnesium alloy AZ31 has been characterised by tensile testing at room temperature. Tests were carried out at various strain rates between 0.00003s^-1 and 0.01s^-1 on material which had been extruded to a bar of approximately 6mm thick, and 80mm wide. Specimens were machined from three orientations relative to the extrusion direction: Parallel, perpendicular, and 45° from the extrusion direction. Significant variations of the properties were observed depending on the extrusion orientation and strain rate. At all strain rates the yield stress declined as the test orientation was rotated away from the extrusion direction. Parallel to the extrusion direction, the yield stress was found to increases markedly with increasing strain rate, whereas at 45° and 90° a lesser influence of strain rate was observed. The work hardening exponent was also influenced by the test orientation. Metallographie studies revealed a microstructure which was predominantly recrystallized: However, some large elongated grains were observed aligned with the extrusion direction, and structure-property correlations were inferred from these observations.