Experimental determination of yield loci for magnesium alloy AZ31 under biaxial tensile stress conditions at elevated temperatures

The finite element analysis (FEA) has become one of the most relevant and most important tools in fields of sheet metal forming for designing processes and dimensioning parts. However, reliability and quality of the numerical results strongly depend on the whole FE-model and especially on the modeling of the material behavior, which shows wide impact on calculated stresses and strains of sheet metal parts. Therefore, the experimental determination of characteristic material data concerning anisotropic and temperature-effects is essential. In this paper the influence of temperature on the yielding and the hardening behavior of the magnesium sheet metal alloy AZ31 are investigated for different uniaxial and biaxial stress conditions. For that purpose an experimental setup has been developed at the Chair of Manufacturing Technology (LFT) which enables biaxial tensile testing of sheet metal. Yield loci of AZ31 are determined as a function of temperature and they are based on solely measurement data of the forming process itself.