Transition of dynamic recrystallization mechanisms of as-cast AZ31 Mg alloys during hot compression

Characterization of microstructure and texture of binary Mg-Ce alloy processed by equal channel angular pressing

“…This behavior could be attributed to at least two reasons: 1) the coarsening of the initial grain size and 2) the presence of precipitate particles along the grain boundaries. Indeed, it has been informed that the migration rate of grain boundaries from the GBBDRX mechanism within coarse grains is very limited [75,79]. As shown by the IQ+ED-IPF map in Figure 10b, the grain boundary contains precipitate particles.…”

“…In this mechanism, the grain boundary bulging between adjacent deformed grains is induced by the grain boundary migration from the low dislocation density side to the high dislocation density side. With further strain, the misorientation between the bulges and deformed grains increases, leading to the transformation of LAGBs into HAGBs, and then the bulged regions become recrystallized grains [75,76]. It has been suggested that bulging of the grain boundaries is stimulated when the pyramidal <c + a> slip system is activated [74].…”

Analysis and Characterization on Dynamic Recrystallization in Casting AZ31 Mg Alloys Under Plane Strain Compression

“…However, it is experimentally found that the temperature of 300 • C is more beneficial to the TDRX and grain refinement than the temperature of 400 • C because the higher strain-hardening rate and flow stress at 300 • C (see Figure 3) drives the TDRX more efficiently. In addition, it is believed that the stress-favored TDRX can effectively weaken the basal deformation texture, enhance the basal slip activity, and reduce the ETW activity [15]. This is why the samples tested at 300 • C show the longer segments of the approximately ideal plastic deformation (see Figure 3).…”

“…Basically, at 300 • C, the coarse-grained AZ31 Mg alloy samples have the better ultimate strength and plastic deformability than those at 400 • C. In addition, the double-peak phenomenon evidently exists in the stress-strain curves with a higher strain rate. Generally, a single peak is understood as the transition of the twinning-induced hardening and the recrystallization-induced softening within coarse-grained Mg alloys [15]. With increasing strain rate, twins become more active within the recrystallized grains, and the secondary hardening and softening could happen and lead to the secondary peak.…”

“…The impact tests on the AZ31 Mg alloy plates along the normal direction [13] indicated that the increased strain rate results in increased flow stress, and that the stress-strain curves show positive strain-rate sensitivity because the strain-rate sensitive double twinning with the high critical resolved shear stress predominantly accommodates the plastic strain. In addition, Zhang et al [14] found that the higher strain rate can more efficiently active the twin-induced dynamic recrystallization (TDRX) [15], and the failure strain of the casting AZ31 Mg alloys tested by the plane strain compression (PSC) is enhanced by the TDRX-induced softening at the higher strain rate.…”