Experimental characterization and modeling of the hardening behavior of the sheet steel LH800

In complex forming processes, sheet metal undergoes large plastic deformations involving significant induced flow anisotropy resulting from the development of persistent oriented (planar) dislocation structures. The aim of the present work is the formulation and identification of a phenomenological model which accounts for the effect of the evolution of this oriented dislocation microstructure on the anisotropic hardening behavior. The model accounts for changes in the size, center, and shape, of the yield surface associated with isotropic, kinematic, and cross hardening, respectively. Identification of the model for the ferritic sheet metal steel LH800 is carried out with the help of shear, reverse shear, and tension–shear tests. The identified model has been validated using it to predict the stress–strain behavior of the material along different tension–shear loading paths and comparison with analogous experimental results. The results and in particular the comparison of theoretical predictions with experimental results clearly demonstrate the need of including cross hardening effects in the modeling of sheet metals like LH800.