Mechanical properties determination of dual-phase steels using uniaxial tensile and hydraulic bulge test

Numerical simulations of sheet metal forming processes need the establishment of highly reliable results, which in turn need the accurate identification of mechanical properties. In this paper a study is presented on the choice of the characterization function of flow stress-strain curve of sheet metal materials, as well as the selection of the best yield locus, based on experimental uniaxial tensile and biaxial hydraulic bulge tests performed on dual-phase steels of industrial interest. To obtain a better characterization of the hardening curve, a combination is made using the uniaxial tensile test data with biaxial hydraulic bulge test results, since bulge test covers a larger range of plastic strain when compared to tensile test. Since the two flow curves have different strain paths, they can’t be directly compared or combined. Therefore, it is necessary a transformation of flow stress-strain curve provided from biaxial bulge test into equivalent stress-strain curve. Different methodologies were applied to transform biaxial stress-strain curve to an equivalent one and the different results are compared and evaluated.