Microstructure and superplasticity of AZ31 sheet fabricated by differential speed rolling

• Published in: Journal of alloys and compounds Vol. 483; no. 1; pp. 279 - 282
• Main Authors: Jeong, H.G., Jeong, Y.G., Kim, W.J.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Kidlington Elsevier B.V 01.08.2009; Elsevier
• Subjects: Applied sciences; Cross-disciplinary physics: materials science; rheology; Elasticity. Plasticity; Exact sciences and technology; Grain boundaries; Materials science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals and alloys; Metals. Metallurgy; Other heat and thermomechanical treatments; Physics; TEM; Transmission electron microscopy; Treatment of materials and its effects on microstructure and properties; Grain boundaries; Metals and alloys; Transmission electron microscopy; TEM; Superplasticity; Grain growth; Rolling; EBSD; Thickness; Magnesium base alloys; Recrystallization; Microstructure; Superplastic flow; Grain refinement; Strain hardening; Elongation (mechanics)
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2008.08.130

Microstructure evolution and superplasticity in AZ31 alloy by differential speed rolling (DSR) with a high-speed ratio (=3) between the upper and lower rolls was examined. With increase in thickness reduction by DSR at 473 K, degree of grain refinement and microstructure homogeneity increased. The microstructure obtained by a single rolling pass for a 70% reduction in thickness consisted of recrystallized grains with a mean size of ∼2 μm, and fraction of HAGBs and average misorientation angle determined by the EBSD analysis were 0.47 and 23.21°, respectively. The DSR AZ31 alloy exhibited enhanced superplasticity as compared with the conventionally processed AZ31. A maximum elongation of 830% was obtained at 2 × 10 −4 s −1 and 673 K. The strain hardening exponent measured at 2 × 10 −4 s −1 and 673 K was as high as 0.71, which could be related to accelerated grain growth in the highly refined microstructure during superplastic flow.