Hydrogen Embrittlement for High Strength Steel Treated with Zinc and Zinc-Nickel Alloy Electroplating from a Sulfate Bath and Hydrogen Permeability

Abstract

Hydrogen embrittlement of SK85 high-strength steel sheets was evaluated using a three-point bending test. Using acid dipping before electroplating, mainly zinc and zinc-nickel alloy electroplating, we examined effects on hydrogen embrittlement in terms of hydrogen permeability of the plating films. Both zinc and zinc-nickel alloy electroplating caused hydrogen embrittlement, which was promoted by hydrogen, based on hydrogen ion reduction during electroplating. Hydrogen embrittlement of zinc-electroplated SK85 steel continued with time and film thinning, but that of the zinc-nickel alloy electroplating was reduced. These results indicate that the zinc film had insufficient permeability for hydrogen embrittlement. However, that of zinc-nickel alloy electroplating enabled hydrogen diffusion from the substrate. Results demonstrate that zinc-nickel alloy electroplating having hydrogen permeability and excellent corrosion resistance is an effective plating method to prevent hydrogen embrittlement of high-strength steel.