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.

KEYWORDS:

• ECAP
• ultrafine
• superplasticity
• texture
• instability

Disclosure statement

No potential conflict of interest was reported by the author(s).

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This work was supported by the National Science Center (Poland) under grant number 2018/31/B/ST8/00942.