Prediction of fatigue resistance of a hot-dip galvanized steel

The paper clarifies the effect of a galvanizing coating on the fatigue stre ngth of a ferritic steel. Depending on experimental conditions and on the m icrostructure of the coating, a reduction in fatigue strength is observed e specially when the coating is thick. Cracks in the galvanizing coating rapi dly form under cyclic loading and then propagate into the steel substrate. This completely modifies the distribution of crack lengths. Very short crac ks are not observed in the steel when galvanized. It is shown that the prop agation of a crack in the substrate from the coating is only possible when the crack completely crosses the coating. By assimilating the coating thick ness to a crack in the steel substrate, the fatigue resistance of hot-dip g alvanized steel can be predicted using the Kitagawa-Takahashi diagram.