Microstructural evolution during the annealing of an extruded AZ31 magnesium alloy

Abstract

Microstructural evolution during the annealing of AZ31 extruded rod at 400 °C has been examined by employing neutron diffraction and electron backscatter diffraction (EBSD). In the as-extruded bar, equiaxed grains smaller than 5 μm and large elongated grains having significant degrees of internal misorientation are oriented mainly with <1010> parallel to the extrusion direction. Rapid grain growth occurs within the 180 sec annealing period at 400 °C at the expense of the small grains with the internal orientation gradient as driving force. After short time annealing, small equiaxed grains are formed inside the large elongated grains, and grains having <1120> parallel to the extrusion direction show preferred growth. As a result, a transition of the main texture component to the <1120> component occurs after annealing for 1800 sec at 400 °C.