Effect of prior copper-coating on the microstructural development and corrosion behavior of hot-dip galvanized Mn containing high strength steel sheet

In the present investigation, the role of copper (Cu) pre-coating has been studied for the development of good quality corrosion-resistant hot-dip galvanized (GI) coating on high strength C-Mn steel sheets. The Cu pre coated GI steel has a more pronounced texture coefficient (TC) of the preferred high atomically dense (0002) crystal plane of Zn coating as compared to the GI steel without pre-coating. It has been observed that the GI coating with Cu pre-coating shows excellent surface quality in comparison to the GI coating without Cu pre coating, which exhibits many bare spots on the final coating. Further, the Cu pre-coated GI steel has revealed the development of a continuous iron aluminide (Fe-Al) intermetallic interfacial layer that has a uniform distribution of dense and equiaxed Fe-Al crystals at its interface with the substrate. It can also be noticed that the Cu pre-coated GI steel has a superior corrosion resistance when compared to the GI steel without pre-coating. This is ascribed to the Cu pre-coated GI steel forming a continuous compact interfacial layer with the maximum atomically dense (0002) crystal plane and a high-quality defect-free coating.