On material batch variation of the dual phase steel DP800

In the present paper a simple material model for the dual-phase steel DP800 is calibrated by means of uniaxial tensile tests and evaluated by use of shear tests. The proposed model consists of a modified version of Ludvik’s law to represent the strain hardening and an isotropic high exponent yield surface. The hardening model was calibrated from tensile specimens taken from two material batches exhibiting quite different behaviour. Shear specimens were tested and modelled in the FEM code LS-DYNA. By a proper choice of the exponent of the yield surface the simulations were in quite good agreement with the experimental results for both batches. Hence, the proposed model seems to extrapolate the strain hardening quite well beyond diffuse necking. The simulations of the shear specimens were also used to calibrate the Cockcroft-Latham failure parameter for all the specimens. The strongest batch had the lowest values of the failure parameter.