a Laboratoire de métallurgie mécanique, UMR CNRS 7633, Centre des Matériaux, Ecole des Mines de Paris, BP 87-91003, Evry cedex, France
b CED, Usinor Recherche et Développement, 1 route de St-Leu, BP 39109, 60761, Montataire, France
Abstract:
Numerical simulations can play a major role in the understanding of deformation mechanisms in zinc coatings of galvanized steel sheets during forming processes. A three-dimensional finite element (FE) simulation of a thin zinc coating on a galvanized steel sheet has been performed taking the multicrystalline structure of the coating into account. Experimental characterization of the gauge length of a real in situ tensile specimen reveals 34 large flat zinc grains; the grain orientations are determined using the electron back-scatter diffraction (EBSD) technique. The geometry and orientation of the grains and the plastic deformation modes specific to hexagonal close-packed (hcp) metals as plastic slip and twinning are incorporated into the modeling using a classical crystal plasticity framework. The constraint effect of the substrate is evidenced by comparing the results to the computation of a zinc layer without substrate under the same loading conditions. Attention is then focused on, respectively, the initiation of plastic activity at the grain boundaries, the multiaxial stress state of the grains, the development of a strain gradient within the thickness.