Analysis of group-buckling and -debonding behaviors of galvannealed coating layer on steel substrates under applied tensile strain

Abstract

The hot-dipped galvannealed steels are composed of brittle coating layer with low failure strain and ductile substrate with far higher failure strain. When tensile stress is applied externally on the coated steels, the coating layer exhibits multiple cracking perpendicular to the tensile direction, and then interfacial debonding occurs, following the buckling of the coating layer in the sample width direction. In the buckling behavior, the series of cracked-coating layers arraying along the tensile direction exhibit group-buckling. In the present work, the group-buckling behavior was observed with the scanning electron microscope and analyzed with 3-dimensional finite element models. It was observed that the preceding buckling of the coating enhances the buckling of the neighboring coating. Such a behavior was well accounted for by the present analysis. © 2009 ISIJ.