Effect of 100°C Heating on Further Ductility Improvement of Friction Stir Processed AZ31 Magnesium Alloy

Abstract

Friction stir processed (FSPed) AZ31 Mg alloy with fine grains was deformed in tension at room temperature (RT) and 100°C to be compared with the same alloy in the extruded condition with coarse grains. Results indicate that texture affects the deformation behavior of AZ31 alloy more than grain refinement does. The work hardening rate of the FSPed alloy shows a prolonged ascending stage at RT and a plateau stage at 100°C, while that of the extruded alloy keeps dropping rapidly. The above discrepancy between the tensile properties of the two test materials arises since basal slip and {10\bar{1}2} tension twin of low critical resolved shear stress are favored by the FSPed texture but not by the extruded texture. 100°C heating allows basal slip and {10\bar{1}2} tension twin to contribute significant improvement to tensile ductility in the FSPed alloy, but hastens the instability in plastic strain of the extruded alloy. The work hardening characteristics and deformation properties of the FSPed specimen in tension at RT and 100°C will be compared further in this paper to examine the different tensile behaviors at these two temperatures.