Evaluating the Hydrogen Embrittlement Resistance of Nickel-Based Coatings as Diffusion Barriers for Carbon Steels

This study evaluates the hydrogen embrittlement (HE) resistance of nickel-based electroplated coatings applied on cold-finished mild steel, with emphasis on their performance as diffusion barriers to impede hydrogen ingress. Nickel coatings were deposited using Watts plating bath under controlled electroplating parameters. Electrochemical hydrogen charging was performed in an alkaline medium at progressively increasing charging current densities to simulate varying levels of hydrogen exposure. Tensile testing was conducted immediately after charging to assess the mechanical response of both uncoated and nickel-coated specimens, focusing on key properties such as elongation, yield strength, ultimate tensile strength, and toughness. The results revealed a gradual degradation in ductility and toughness for the uncoated steel samples with increasing hydrogen content. In contrast, the nickel-coated specimens maintained mechanical stability up to a critical hydrogen threshold, beyond which a pronounced reduction in tensile response was observed. Fractographic analysis supported these trends, revealing a transition from ductile to brittle fracture characteristics with increasing concentrations of hydrogen. These findings highlight the protective capabilities and limitations of nickel-based coatings in mitigating hydrogen-induced degradation, offering insights into their application in industries where hydrogen embrittlement of structural materials is a major concern.