THE INFLUENCE OF DEFORMATION MECHANISMS ON RUPTURE OF AZ31B MAGNESIUM ALLOY SHEET AT ELEVATED TEMPERATURES

摘要

Gas-pressure bulge tests were conducted on Mg alloy AZ31Bwrought sheet until rupture at temperatures from 250 to 450°C.The rupture orientation was observed to change with formingpressure, which controls the forming strain rate, at 350 to 450°C.This phenomenon is a result of associated changes in themechanisms of plastic deformation. At slow strain rates (≤ 3×10~(-2)s~(-1)), cavity interlinkage associated with grain boundary sliding(GBS) creep induced rupture along the sheet rolling direction(RD). At fast strain rates (≥ 3×10~(-2) s~(-1)), flow localization(necking) associated with dislocation-climb-controlled (DC) creepinduced rupture along the long-transverse direction (LTD), aresult of mild planar anisotropy. Biaxial bulge specimens tested at250 to 300°C ruptured explosively, hence preventing any furtheranalysis.