Mechanical properties and microstructure of a Mg alloy AZ31 prepared by equal-channel angular pressing

A squeeze cast magnesium-aluminium-zinc alloy AZ31 was subjected to equal-channel angular pressing (ECAP) at 200 degrees C up to four passes following route B-C. The grain size was reduced by a factor of about 100-200 through ECAP processing. The mechanical properties of as cast (non-pressed) and the ECAP-processed material were examined using compression tests from room temperature to 300 degrees C. ECAP pressing resulted in a significant increase of the room temperature yield strength of the alloy. At elevated temperatures (200 and 300 degrees C) an inverse dependence was found, i.e. the yield stress in the ECAP-processed specimens was lower than in the cast material. A recrystallized structure was formed only after four passes of ECAP. Dynamic recrystallization occurred during the deformation at elevated temperatures (300 degrees C). Coarser recrystallized grains were formed in the specimen that had undergone four passes of ECAP. The strain imposed by ECAP influences the heterogeneity of the final microstructure of specimens after compression tests. (C) 2006 Elsevier B.V. All rights reserved.