Evaluation of Hydrogen Embrittlement for High Strength Steel by Three-Point Bending Test and Application to Zinc Electroplating

Abstract

 The hydrogen embrittlement of the SK85 high strength steel sheet was evaluated by three-point bending test, and the effect of zinc electroplating and zinc-nickel alloy electroplating on the hydrogen brittleness of steel was examined by this method. It was found that the evaluation of hydrogen brittleness for the high strength steel sheet by three-point bending test was possible to obtain the effective result. Zinc electroplating made hydrogen brittleness promote by the hydrogen based on the reduction of hydrogen ion during the electroplating, because zinc plating acted as a barrier film for hydrogen evolution from the substrate. The hydrogen brittleness of zinc-nickel alloy electroplating was suppressed in comparison with that of zinc plating. It seems that large number of cracks in a film enable the hydrogen diffusion.