A New Constitutive Model for AZ31B Magnesium Alloy Sheet Deformed at Elevated Temperatures and Various Strain Rates

• Published in: High temperature materials and processes 2014-12, Vol.33 (6), p.499-508
• Main Author: Nguyen, Duc-Toan
• Format: Article
• Language: English
• Subjects: 81.05.Bx; Alloys; AZ31B magnesium alloy sheet; finite element method; high temperature stress-strain curves; Magnesium; Stress-strain curves; work hardening and softening
• ISSN: 0334-6455; 2191-0324
• DOI: 10.1515/htmp-2013-0109

In this study, a new constitutive model is established for AZ31B magnesium alloy sheet at elevated temperatures and strain rates in order to describe two competing mechanisms for deformation, i.e. both work-hardening and softening stage of AZ31B magnesium alloy sheet. Stress-strain curves obtained by conducting uni-axial tensile tests at elevated and strain rates were first separated at the maximum stress and corresponding strain values. Voce's law [25] was then employed to fit separated hardening and softening stage. A MATLAB tool is used to determine material parameters by using least square fitting method at various temperatures and strain rate. The mergence of separated work-hardening and softening equations is in good agreement with experimental data. The parameters of fitting curves are utilized to determine them as a function of temperature and strain rate using a surface fitting method. The final equation is then implemented to predict stress-strain curves at various temperatures and strain rates. The proposed equation showed the good comparability between the simulation results and the corresponding experiments.