A review of dynamic recrystallization phenomena in metallic materials

Magnesium and its alloys do not in general undergo the same extended range of plasticity as their competitor structural metals. The present work is part I of a study that examines some of the roles deformation twinning might play in the phenomenon. A series of tensile test results are reported for the common wrought alloy AZ31. These data are employed in conjunction with a simple constitutive model to argue that View the MathML source twinning (which gives extension along the c-axis) can increase the uniform elongation in tensile tests. This effect appears to be similar to that seen in Ti, Zr and Cu–Si and in the so called TWIP phenomenon in steel.

Twinning and the ductility of magnesium alloys Part I: “Tension” twins

The texture and anisotropy of magnesium–zinc–rare earth alloy sheets

http://li.mit.edu/Stuff/RHW/Upload/07-01_Lou_XY_Hardening_evolution_paper.pdf

Hardening evolution of AZ31B Mg sheet

Superior light metals by texture engineering: Optimized aluminum and magnesium alloys for automotive applications

Influence of grain size on the compressive deformation of wrought Mg-3Al-1Zn

Non-Schmid behaviour during secondary twinning in a polycrystalline magnesium alloy

Effect of microalloying with rare-earth elements on the texture of extruded magnesium-based alloys

The use of magnesium alloys in structural applications has great potential for the lightweighting of transportation vehicles. Research within the CAST Cooperative Research Centre has tackled some of the important issues related to the use of magnesium in structural applications. To this end, a new alloy with extrudability and properties similar to 6000 series aluminum alloys has been developed. Furthermore, a method of laser heating magnesium alloys before self-piercing riveting has enabled high-integrity joining between magnesium components or between magnesium and dissimilar metals. In this paper, new technologies and improved understanding of the deformation behavior of wrought magnesium alloys are discussed in light of key metallurgical features such as alloy composition, grain size, and work hardening rate.

Magnesium alloy applications in automotive structures

The microstructural evolution is examined during the hot compression of magnesium alloy AZ31 for both wrought and as-cast initial microstructures. The influences of strain, temperature, and strain rate on the dynamically recrystallized microstructures are assessed. Both the percentage dynamic recrysallization (DRX) and the dynamically recrystallized grain size were found to be sensitive to the initial microstructure and the applied deformation conditions. Lower Z conditions (lower strain rates and higher temperatures) yield larger dynamically recrystallized grain sizes and increased percentages of DRX, as expected. The rate with which the percentage DRX increases for the as-cast material is considerably lower than for the wrought material. Also, in the as-cast samples, the percentage DRX does not continue to increase toward complete DRX with decreasing Z. These observations may be attributed to the deformation becoming localized in the DRX fraction of the material. Also, the dynamically recrystallized grain size is generally larger in as-cast material than in wrought material, which may be attributed to DRX related to twins and the inhomogeneity of deformation. Orientation maps of the as-cast material (from electron backscattering diffraction (EBSD) data) reveal evidence of discontinuous DRX (DDRX) and DRX related to twins as predominant mechanisms, with some manifestation of continuous DRX (CDRX) and particle-stimulated nucleation (PSN).

Aiden Beer

Papers

Influence of grain size on the compressive deformation of wrought Mg-3Al-1Zn

Non-Schmid behaviour during secondary twinning in a polycrystalline magnesium alloy

Effect of microalloying with rare-earth elements on the texture of extruded magnesium-based alloys

Magnesium alloy applications in automotive structures

Microstructural Development during Hot Working of Mg-3Al-1Zn