Effect of processing parameters on the quality of hot dip galvanizing of cold rolled steel”

Abstract

Steel is still the main construction material for automobiles, general equipment and industrial machinery. Hot dipping has been proven to be an excellent method of corrosion protection of steels for a wide range of applications worldwide. Coatings of Zn-alloys on steel sheet have high corrosion resistance due to the corrosion prevention ability from Zn and the passivation of these alloys. Bath composition, immersion temperature, time and substrate composition are the hot dipping parameters that more influence on the thickness and corrosion resistance of the deposited coating. The chemical composition of the zinc bath can strongly influence on the hot-dip galvanized coatings. In this work, the effects of aluminum, magnesium and tin addition on the surface morphology were investigated. Moreover, the influence of zinc bath and Si contents in the steel composition has been studied and the corrosion resistance of hot-dip galvanized steel were investigated. The corrosion behavior of steel samples galvanized with zinc and Zn- alloys containing different wt. % was analyzed by various corrosion tests such as potentiodynamic polarization, Tafel lines and electrochemical impedance spectroscopy (EIS) techniques. Salt spray test was employed in order to study the corrosion products of the specimens. Surface morphology, the composition of coating layers and nature of the corrosion products were also investigated using field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray analysis (EDX) and X-Ray diffraction (XRD) techniques, respectively.