Mechanical Behaviour of Dual Phase Steels under Different Strain Rates

The objective of this research was to analyse the stress and strain behaviours of the triaxiality specimens (specimens of different shaping) of dual-phase steels, respectively DP600 and DP800, whose microstructures mainly comprise ferrite and martensite phases. These steels find wide application in the automotive industry, which is constantly searching for better quality materials in the aim of increasing vehicle safety, protecting the environment, and reducing fuel consumption. In this case, for all tested specimens the experimental uniaxial tensile tests were performed at three different strain rates, 0.0083 s−1, 0.042 s−1, and 0.16 s−1, to determine mechanical properties such as stress, strain, yield strength, and ultimate tensile strength of mentioned steels. In addition, uniaxial tensile tests with characteristics similar to those experimental were carried out through the finite element modelling method using the Mat_Picewise_Linear_Plasticity_024 model, to determine the mentioned mechanical properties, but also to determine the failure parameters or plastic strain up to failure, of all triaxiality modelled specimens. The obtained results were validated by comparing the experimental results with numerical simulation results. The comparative scale of accuracy between both steels was made at the fracture strain, and the average accuracy of both steels for the standard (s) specimens was < 1 %, for the (20a) specimens 1.50 %, for the (4a) specimens 4 %, and for (a) specimens 3.50 %. Finally, it was concluded that the proposed material model and calibrated failure data fitted very well.