Corrosion Behavior of Fe-Al-Zn Interphased Dual Phase Steel in Marine Environment

Abstract

Intercritical heat treatment operation has been in use for the development of Dual Phase Steel (DPS) and has been found to improve the mechanical properties of the steel. In spite of the enhancement a limitation was however observed as to its corrosion susceptibility. In a bid to further enhance the corrosion resistance of the DPS while maintaining its mechanical properties, galvanealing operation was adopted which involving the immersion of the DPS into Al-Zn melt and subsequently subjecting it to annealing operation at 550 ° C. Weight loss and linear polarization technique were used to measure or evaluate its resistance in 3.5% NaCl (a simulated marine environment). A minimum of 3 samples was used per immersion time. From the result, it was observed that there is a general sharp decrease in the corrosion rate of the GAS as compared to the control sample. The sample immersed and allowed to dwell in the melt for 20 seconds and further annealed with a soaking time of 20 minutes exhibited the highest corrosion resistance. The polarization curve also shows that the substrate was generally passivated, and this is as a result of the Al-Zn/Fe adhesiveness.