Magsure Zn-Al-Mg Coating: Superior Corrosion Resistance and Formability

Magsure is an advanced Zn–Al–Mg hot-dip alloy coating designed for structural-grade steel requiring superior corrosion resistance without compromising formability. In this study, Magsure coatings were produced at 80, 120, 275, and 450GSM, and their microstructure and corrosion behaviour were investigated. Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM–EDS) and X-Ray Diffraction (XRD) analyses confirmed the presence of MgZn₂ intermetallic phases distributed within the coating microstructure, with a phase fraction of 21–27 vol%, contributing to enhanced corrosion protection through combined sacrificial and barrier effects. To establish industrial relevance, a direct comparison was made between GI 275GSM and Magsure 275GSM. Formability tests, including cupping, drawing, and Hole Expansion Ratio (HER), showed that Magsure 275GSM retained formability comparable to conventional GI 275 GSM, with no major loss in forming performance. In contrast, corrosion testing by neutral salt spray, cyclic corrosion exposure, and electrochemical impedance spectroscopy revealed a pronounced increase in corrosion life for Magsure 275 GSM relative to GI 275 GSM. The results demonstrate that the Zn–Al–Mg coating system delivers a significant improvement in corrosion durability while preserving the formability required for practical fabrication, making Magsure a strong candidate for high-durability applications in aggressive service environments.