Grain Refinement of Magnesium Alloy AZ31 under Torsion Extrusion with a Square-Hole Die

Abstract

Grain refinement and crystal orientation of magnesium alloy AZ31 under torsion extrusion with a square-hole die are investigated. The optimum temperature and ratio of the die rotation speed to the extrusion speed were clarified, resulting in uniformly distributed fine grains with sizes in the range 1- m over the entire cross section of the worked specimen. The crystal orientation of the specimen was determined by electron backscatter diffraction and compared with that of a conventionally extruded specimen. In the case of torsion extrusion, a very strong <0001> texture was observed along the extrusion axis, especially in the center region of the cross section. In contrast, the <0001> direction of many grains in the conventionally extruded specimen tended to be perpendicular to the extrusion axis.

Process optimization of the extrusion through rotating container with AZ31 magnesium alloy

“…For each die, the optimum temperature and the speed ratio required to obtain a uniform distribution of 1-2 µm fine grains over the section of the billet were clarified. The billet processed by torsion extrusion had a very different crystal orientation than that of the conventionally extruded billet [2].…”