Influence of thickness of intermetallic layers on fracture resistance of galvanized coatings

Galvanized coatings, commonly used for corrosion protection of steelsʹ surfaces, are susceptible to crack formation and propagation due to thermal stress and deformation from post-processing. To identify geometrical parameters governing crack propagation of the coating layers, mechanics of crack propagation is numerically analyzed using finite element simulations. Focuses are given to addressing the influence of the coating thickness on fracture resistance of the zinc–iron intermetallic layers of galvanized coatings that are subjected to four-point bending. The study demonstrates that a decrease of the delta phase layer with respect to the zeta phase layer improves crack resistance of the coating layers. Furthermore, increasing the thickness of eta phase layer is shown useful for retarding crack growth in the intermetallic layers. Galvanizing protocols may be tailored to achieve a combination of intermetallic layer thicknesses that enhances the coatingsʹ crack resistance.