A Study on Yield Function for Ti-6Al-4V Titanium Alloy Sheets at Elevated Temperatures

Currently, the finite element (FE) method simulation technique is being widely applied to optimize the forming process. To achieve high-accuracy FE simulation results, the identification of material properties and deformation characteristics such as yield criteria is important. In this study, characterisation of plastic deformation behavior of Ti-6Al-4V titanium alloy using anisotropic sheets were carried out using, biaxial tensile tests at 600 A degrees C with a cruciform specimen. The test was performed until the specimen was broken down. The experimental results for the yield locus were first compared with other theoretical models to show the mismatch of the conventional function. A new yield function was then proposed in this study to describe not only the anisotropic but also the asymmetric behavior between the tension and compression of Ti-6Al-4V titanium alloy sheets using a fitting equation to determine the material constants of the yield function. Finally, yield loci at other elevated temperatures were obtained based on the relationship between tension yield stress and temperature.