Effect of Microcracks Formed in Zn-Ni Alloy Plating Films on Hydrogen Embrittlement of High Strength Steel

Abstract

Zn-Ni alloy plating from sulfuric acid baths has excellent hydrogen embrittlement resistance for high strength steels. In this study, we investigated the factors that contribute to the hydrogen embrittlement resistance of Zn-Ni alloy plating. In Zn-Ni alloy plating, microcracks are formed in the coating. Hydrogen embrittlement was accelerated by mechanical sealing of these microcracks, and the microcracks that form in the coating were a pathway for hydrogen release. Therefore, these microcracks are found to play an extremely important role in suppressing hydrogen embrittlement. It is suggested that a gap in the plating film that can release hydrogen-induced vacancies is important to suppress hydrogen embrittlement due to plating.