Hot working and crystallographic texture analysis of magnesium AZ alloys

Abstract

The hot working behaviour of magnesium AZ (e.g. AZ31; Al: 3%, Zn: 1%) alloys and their associated crystallographic texture evolution is reviewed. Under hot working conditions, the stress-strain curves show flow softening at all the temperatures and strain rates indicating dynamic recrystallisation (DRX) is predominant. The mean size of the recrystallised grains in all the alloys decreases as the value of Zener-Hollomon parameter Z increases. The hot working range of the alloys dwell between 200 and 500uC and the strain rates between 10 23 and 5 s 21 . The hot working of AZ series alloy shows discontinuous DRX as the main mechanism. Equal channel angular processing shows continuous DRX. The constitutive equation development shows a linear relationship between the stress and the Z parameter. The activation energy for the alloys ranges from 112 to 169 kJ mol 21 and Z values range from 10 7 to 10 14 s 21 . Textural examinations show basal texture as the predominant orientation.

Detwinning behavior of Mg–3Al–1Zn alloy at elevated temperatures

“…An increase in tensile or compressive load will even favor contraction twinning [1]. Compression or tension along the rolling direction, transverse direction and normal direction of a hot-rolled plate often induce quite different deformation behavior, too [11].…”

Microstructure and mechanical properties of the AZ31 magnesium alloy sheets processed by asymmetric reduction rolling

“…However, the magnesium alloys always exhibit poor ductility and workability at room temperature due to its limited slip systems with hexagonal close packed (HCP) crystal structure. Formability of magnesium alloys sheet is linked with their microstructure and texture [3][4][5]. The non-basal slip is hardly operative at room temperature because the critical resolved shear stresses (CRSS) of the non-basal slip systems on prismatic and pyramidal planes are much higher than that of a basal slip system at low temperature [6].…”

Cyclic hardening/softening behaviour in AZ31B magnesium alloy based on infrared thermography

“…Magnesium alloys have attracted increasing attention due to their excellent specific properties, such as low densities, high specific strength, good conductivity of heat and electricity and ease of recycling, which makes them become potentially suitable candidates for replacing some materials in the fields of aerospace, rail transportation and automobile. 1,2 Magnesium alloy components are mostly subjected to cyclic loading, 3 and the main failure mode is fatigue fracture. Because of the magnesium alloy of hexagonal closepacked (HCP) structure characteristics with less slip system at room temperature and the poor plastic deformation ability, the fatigue problems are more prominent than steel materials.…”