Multidirectional forging of AZ91 magnesium alloy and its effects on microstructures and mechanical properties

摘要

AZ91 alloy was subjected to multidirectional forging (MDF) and the relationship between microstructures and mechanical properties generated by MDF were investigated. The results showed that after 1 MDF pass grain size of the alloy decreased compared with as-cast alloy, and the amount of recrystallization grains increased when the MDF temperature increased from 250 ℃ to 400 ℃. With increasing the MDF passes at 350 ℃, grains of the alloy were gradually refined. A typical basal texture was obtained after 1 MDF pass, and then the basal pole scattered with the increase of MDF passes. Mg_(17)Al_(12) phases were precipitated along grain boundaries during MDF, which could hinder the growth of recrystallization grains. Both tensile strength and elongation to failure of the alloy were significantly enhanced till 3 MDF passes with increasing the MDF passes.