Anisotropy, Tension-Compression Asymmetry and Texture Evolution of a Rare-Earth-Containing Magnesium Alloy Sheet, ZEK100, at Different Strain Rates and Temperatures: Experiments and Modeling

Published

August 1, 2017

Author(s)

Saadi A. Habib, Akhtar S. Khan, Thomas H. Gnaupel-Herold, Jeffrey T. Lloyd, Scott E. Schoenfeld

Abstract

Mechanical responses and texture evolution of rare earth containing magnesium alloy, ZEK100, sheet are measured under uniaxial (tension-compression) loadings along the rolling direction (RD), 45° to rolling direction (DD), transverse direction (TD) and normal direction (ND) at the strain rate and temperature ranges of 10^-4 - 3x10³ s^-1 and 22°C & 150°C, respectively. Texture evolution is measured at a strain increment between 2-10% in compression and tension at both 10^-4 and 3x10³ s^-1 and at 22°C and 150°C. Measured pole figures reveal relatively weak basal pole intensity with a spread of basal poles from ND toward TD. As a consequence, the yield stress in both tension and compression is greatest in RD and decreases with change in orientation from RD to TD. The material shows positive strain rate sensitivity, tension-compression asymmetry and anisotropy that is a function of temperature and strain rate. Strain hardening behavior in both tension and compression presents the characteristics of twinning deformation even at elevated temperature. Crystal reorientation due to twinning was observed in compression loading along all directions and tension in the TD. While some change is observed in mechanical properties in compression as the strain rate increases from 10^-4 to 3x10³ s^-1, minimum texture differences are observed between the two strain rates. In order to understand the deformation mechanisms that result in these complex material properties, a reduced-order crystal plasticity model that defines extension twinning, basal slip, and non-basal slip as the deformation mechanisms is employed to model the experimental data. The model accurately predicts an increase in hardening rate while maintaining constant activity of twinning as the strain rate increases.

Citation

International Journal of Plasticity

Volume

95

Pub Type

Journals

Download Paper

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Keywords

Twinning, quasi-static, dynamic, high strain rate, slip

Citation

Habib, S. , Khan, A. , Gnaupel-Herold, T. , Lloyd, J. and Schoenfeld, S. (2017), Anisotropy, Tension-Compression Asymmetry and Texture Evolution of a Rare-Earth-Containing Magnesium Alloy Sheet, ZEK100, at Different Strain Rates and Temperatures: Experiments and Modeling, International Journal of Plasticity, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=922360 (Accessed April 26, 2024)