Strong strain path dependence of strain localizations and fracture in magnesium AZ31 sheet

Alkan K., Aytuna O. B., GÜLER B., EFE M.

JOURNAL OF MAGNESIUM AND ALLOYS, vol.8, no.2, pp.472-479, 2020 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 8 Issue: 2
  • Publication Date: 2020
  • Doi Number: 10.1016/j.jma.2020.03.002
  • Journal Name: JOURNAL OF MAGNESIUM AND ALLOYS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.472-479
  • Keywords: Formability, Twinning, Biaxial, DIC, AZ31, ROOM-TEMPERATURE, MG ALLOY, DEFORMATION, BEHAVIOR, TEXTURES, MICROSTRUCTURES, PROPAGATION, MECHANISM, FAILURE, TWINS
  • Middle East Technical University Affiliated: Yes

Abstract

This study compares the deformation and fracture behavior of a basal-textured Mg AZ31 alloy sheet under uniaxial tension and biaxial stretching by using an in-plane biaxial test setup capable of observing and measuring the deformation at both meso (millimeter) and microstructure scales. Strain distributions at the mesoscale and accompanying fracture surfaces indicate a significant dependence on strain path. At the microscale, limited slip activity in biaxial case promotes contraction twins, where severe strain localizations (epsilon(max)/epsilon(mean) approximate to 20) to the twins and their boundaries cause mainly transgranular fracture. This leads to a brittle, and a more pronounced shear-type fracture under biaxial stretching. In uniaxial case, considerable tensile twinning activity reorients the initial texture for slip activity. Strain localizations (epsilon(max)/epsilon(mean) approximate to 2) to the grain interiors and boundaries initiate mainly intergranular fracture. Samples fail by displaying both brittle and ductile fracture structures, with smaller shear lips compared to the biaxial case. (C) 2020 Published by Elsevier B.V. on behalf of Chongqing University.