ABSTRACT
Hydrogen uptake during electrochemical metal plating of high strength steels can cause severe embrittlement depending on the plating parameters. In situ hydrogen permeation measurements have been performed during electrochemical deposition of ZnNi coatings on 100 µm membranes of high strength steel (yield strength 2000 MPa) in order to evaluate non-critical plating conditions. For characteristic plating parameters a hydrogen balance was made up over the whole plating period by estimating the total amount of hydrogen electrochemically produced, measuring the total amount of permeated hydrogen and finally calculating the percentage of permeated hydrogen related to the total amount of electrochemically produced hydrogen. These data were correlated with the hydrogen embrittlement of notched round tensile specimens plated under the same conditions. The likelihood of embrittlement was correlated with the amount of hydrogen collected from notched tensile specimens during thermal hydrogen effusion treatment (24 h/190°C). Systematic investigations revealed process conditions which allow the plating of high strength steel with ZnNi coating without creating hydrogen embrittlement. The results are compared with the effect of zinc, nickel and cadmium coatings.
