Microstructure, texture, and instability during superplastic deformation of ECAP-treated AZ31 Mg alloy

Abstract

An ultrafine-grained AZ31 Mg alloy processed through multipass equal channel angular pressing (ECAP) achieved 5 and 0.9 µm mean grain sizes after two and four passes, respectively. The deformation behaviour of the alloy was studied through tensile testing at high temperatures. A 410% superplastic elongation was achieved at 250°C during the tensile deformation of the four-pass-processed alloy. The Haehner criterion allowed the prediction of the stable uniform deformation of the alloy. The strain rate sensitivity of 0.38 and equiaxed microstructure suggested grain boundary sliding as the rate-controlling mechanism. The slip system's contribution to superplasticity was discussed using related Schmid factors. Slip activity prevalence at high strains induced a texture-strengthening effect and allowed low-angle grain boundary formation at high strains.

Investigating the role of processing temperature on the microstructure evolution, mechanical properties, and corrosion behaviour of equal channel angular pressed AZ31 Mg alloy

“…Therefore, selecting the processing temperature is crucial to retain the benefit of the grain refinement achieved during the plastic deformation. By adopting ECAP, grain refinement was achieved and increased tensile strength, corrosion resistance, surface properties and wettability of AZ31 Mg alloy have been achieved as demonstrated in the literature [15,[20][21][22]. However, the information on the role of processing temperature on the microstructure evolution of AZ31 Mg alloy during ECAP is insufficient.…”