Fabrication of Low Temperature Superplastic AZ91 Mg Alloys Using Simple High-Ratio Extrusion Method

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Original languageEnglish
Pages (from-to)875-880
Journal / PublicationKey Engineering Materials
Online published15 Jan 2003
Publication statusPublished - 2003
Externally publishedYes


Title6th Asia-Pacific Symposium on Engineering Plasticity and Its Applications (AEPA2002)
LocationUniversity of Sydney
Period2 - 6 December 2002


There have been numerous efforts in processing metallic alloys into fine-grained materials, so as to exhibit high strain rate superplasticity (HSRSP) and/or low temperature superplasticity (LTSP). The current study applied the most simple and feasible one- or two-step extrusion methods on the most popular and low-priced commercial magnesium alloy, namely the AZ91D ingot, to result in superior low temperature superplasticity. The one-step extrusion was undertaken using a high extrusion ratio above 100:1 (better above 150:1) at 250-350°C. And the two-step extrusion was conducted with an extrusion ratio of 20:1 to 50:1 for the first step at 250-350°C, followed by a second-step extrusion with an extrusion ratio of 3:1 to 8:1 at 200-300°C. The initial grain size in the purchased AZ91D ingot was 125 μm, and that after one- or two-step high extrusion ratio extrusion became ∼2.5 μm, resulting in superior low temperature superplastic elongation up to ∼1200% at 300°C and 1×10-3 s-1. The low flow stress and the high strain rate sensitivity of 0.42 both suggest that grain boundary sliding has smoothly operated under these loading conditions. The current results imply that the simple high-extrusion ratio extrusion method might be a feasible processing mean for industry applications.

Research Area(s)

  • Extrusion, Low Temperature Superplasticity, Mg Alloy