Hydrogen Embrittlement and Corrosion Resistance of Austenitized Zn-Al-Mg-Coated Medium-Mn Steel

Abstract

In this study, we investigated hydrogen absorption during austenitizing, as well as the resistance to both hydrogen embrittlement (HE) and corrosion, in Zn-Al-Mg-coated medium-Mn steel in comparison to Zn-Al-coated steel. After austenitization at 750 °C for 5 min, the Zn-Al-Mg-coated steel had a higher hydrogen content than the Zn-Al-coated steel, likely due to the reaction of Mg with water vapor in the furnace atmosphere, which led to the formation of an MgO layer on the outermost surface. Despite the higher hydrogen content, silver decoration analysis revealed that most of the absorbed hydrogen remained confined within the coating layer, limiting its diffusion into the steel substrate and thereby maintaining HE resistance comparable to that of the Zn-Al coated steel. The Zn-Al-Mg-coated specimen also exhibited higher corrosion resistance than the Zn-Al-coated specimen, likely due to the formation of a complex compound of MgO and Al2O3.

Keywords: Zn-Al-Mg Coating, Hydrogen absorption, Hydrogen Embrittlement, Corrosion resistance, Medium-Mn steel