Hydrogen entry behaviour of hot-dip Al–Mg–Si coated steel

A ternary hot-dip Al–Mg–Si coating was formed on a steel substrate and tested as an alternative to conventional zinc coatings particularly in high-strength steel application with respect to hydrogen entry behaviour. Hydrogen entry behaviour was evaluated under wet–dry conditions using a Devanathan cell. The new hot-dip Al–Mg–Si coating shows relatively low corrosion potential during the initial stage of the wet period; however, the potential shifts in a noble direction in a short time resulting in smaller amount of hydrogen entry than that in the conventional zinc coating.

► New hot-dip Al–Mg–Si coating as an alternative to conventional zinc coating. ► Hydrogen entry behaviour under wet–dry condition was studied. ► The Al–Mg–Si coating showed moderate corrosion potential at about −0.7 V vs. SSE. ► No red rust was found in the Al–Mg–Si coating after wet–dry test. ► The Al–Mg–Si coating showed smaller hydrogen entry than zinc coating.