Modeling the mechanical behavior of a multicrystalline zinc coating on a hot-dip galvanized steel sheet

Numerical simulations can play a major role in the understanding of deforma tion mechanisms in zinc coatings of galvanized steel sheets during forming processes. A three-dimensional finite element (FE) simulation of a thin zin c coating on a galvanized steel sheet has been performed taking the multicr ystalline structure of the coating into account. Experimental characterizat ion 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-p acked (hcp) metals as plastic slip and twinning are incorporated into the m odeling using a classical crystal plasticity framework. The constraint effe ct of the substrate is evidenced by comparing the results to the computatio n of a zinc layer without substrate under the same loading conditions. Atte ntion is then focused on, respectively, the initiation of plastic activity at the grain boundaries, the multiaxial stress state of the grains, the dev elopment of a strain gradient within the thickness. (C) 2000 Elsevier Scien ce B.V, All rights reserved.