Grain Refinement of Magnesium Alloys by CONFORM: A Continuous Severe Plastic Deformation Route?

Abstract:

Effective grain refinement through equal channel angular pressing (ECAP) for magnesium (Mg) alloys has been demonstrated by many researchers. Although with the capability to achieve superplasticity, the batch mode nature of this method and the required repetitive processing to attain ultrafine grained structure have prohibited it from being widely used in large-scale industrial production. In this study, a well-established metal forming method – the continuous extrusion forming (CONFORM) process – was employed as a severe plastic deformation route to refine the microstructure of Mg alloys. Cast Mg-3%Al-1%Zn (AZ31) rods were used as the feedstock and the cast structure (grain size of ~150 microns) was refined to ~1 micron after one pass CONFORM extrusion. Uniaxial tensile tests of the as-extruded samples were conducted at a temperature of 473K and an elongation of ~200% was achieved under a strain rate of 1×10^-4 s^-1. The significant grain refinement effect was attributed to the severe shear deformation occurred during the CONFORM process, which is very similar to ECAP but with even higher effective strains. The most important advantage of CONFORM over ECAP is that the former is a continuous route, so it is able to produce long products. It was also shown that CONFORM could be an additional forming method for Mg alloys to conventional rolling, forging and extrusion.

• Periodical: Materials Science Forum (Volumes 706-709)
• Pages: 1781-1786
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.706-709.1781
• Online since: January 2012
• Authors: You Liang He, Fei Gao, Bao Yun Song, Rong Fu, Gui Ming Wu, Jian Li, Lan Jiang
• Keywords: Continuous Extrusion Forming, Grain Refinement, Magnesium Alloy, Severe Plastic Deformation (SPD), Superplasticity

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