Strain Hardening Behavior in Mg-Al Alloys at Room Temperature

Abstract

The effect of Al on the strain hardening behavior of as-extruded Mg-xAl (x=1, 2, 3 and 4wt%) magnesium alloys is investigated using uniaxial tensile tests at 10(-3)s(-1) at room temperature. The strain hardening rate, the strain hardening exponent, and the hardening capacity are obtained from true stress-true plastic strain curves. In as-extruded Mg-Al alloys, the Al element is completely dissolved in the -Mg matrix. With increasing Al content, the average grain sizes of these samples decrease from 16.9 to 10.7 mu m. The strain hardening rate increases from 515 to 924MPa, then reduces to 818MPa at (sigma-sigma(0.2))=90MPa. The strain hardening exponent n increases from 0.125 to 0.149 and then reduces to 0.142, while the hardening capacity Hc increases from 0.71 to 0.90 and then reduces to 0.80. The train hardening rate, the strain hardening exponent n, and hardening capacity Hc reach peak value in Mg-3Al. The difference in the strain hardening responses of as-extruded Mg-Al alloys may mainly be influenced by weaker basal texture and smaller average grain size with increasing Al content.