Microstructural evolution during the annealing of an extruded AZ31 magnesium alloy

Abstract

a b s t r a c tMicrostructural 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 m and large elongated grains having significant degrees of internal misorientation are oriented mainly with < 1 01 0 > parallel to the extrusion direction. Rapid grain growth occurs within the 180 s 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 < 1 12 0 > parallel to the extrusion direction show preferred growth. As a result, a transition of the main texture component to the < 1 12 0 > component occurs after annealing for 1800 s at 400 • C.

Effect of pre-deformation anneal on the microstructure and texture evolution of Mg–3Al–1Zn–0.7Sr alloy during hot extrusion

“…Yi et al [24] have previously seen a similar change of texture in AZ31 alloys as a result of annealing after extrusion. They have reported that the texture component in the IPF moves from the (10-10) to the (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) corner with increasing post-annealing time.…”

Microstructure and texture development in hydrostatically extruded Mg–Al–Zn alloys during tensile testing at intermediate temperatures

“…The development of a texture with a 11.0 component has been observed by various authors as a result of the growth of recrystallised grains in conventional Mg-Al-Zn alloys [8,34]. It can be a result of DRX if fully recrystallised microstructures are achieved [9,35] or the result of static recrystallisation (SRX) [8].…”

“…It can be a result of DRX if fully recrystallised microstructures are achieved [9,35] or the result of static recrystallisation (SRX) [8]. In Fig.…”

“…For the alloy AZ31, Yi et al [8] demonstrated that recrystallised grains generated during an extrusion experiment were mainly produced by rDRX and that the high degree of internal misorientation (stored energy) of these grains provides the driving force for the grains to grow during annealing treatments. Furthermore, grain growth plays an important role in changing the texture of the profile.…”

“…Two main mechanisms have been discussed in this context: One of these is discontinuous dynamic recrystallisation (dDRX); the other is rotational dynamic recrystallisation (rDRX). In the former, new grains are mainly formed at grain boundaries and form a mantle around them by grain boundary bulging due to strain-induced boundary migration [8]. The dDRXed grains are therefore expected to be relatively strain-free.…”