Enhanced ductility in high-strength fine-grained magnesium and magnesium alloy sheets processed via multi-pass rolling with lowered temperature

摘要

Ductility enhancement up to about 28-39% in fracture elongation with simultaneous strengthening was achieved in fine-grained magnesium and magnesium alloy sheets by multi-pass rolling with lowered temperature suitable for industrial fabrication. Specifically, high strengths at yielding following slip-dominated Hall-Petch relations were achieved owning to the naturally twinning's replacement by pyramidal under intense basal texture. These Hall-Petch relations had a high slope of 190 MPa mu m(1/2) and frictional stresses ranging from 40 MPa to 144 MPa. The variation in frictional stress matched well with solid solution hardening and/or precipitation hardening. Enhanced uniform elongation was strongly correlated with improved strain-hardening rate via introducing solid solution and/or fine precipitates in Mg alloys compared with pure Mg, and conversely post-necking elongation (local elongation) as well as cold-workability under compressive stress was strikingly weakened by the restriction of dynamic recovery. (C) 2016 Elsevier B.V. All rights reserved.