Makoto Hino1, Hideaki Asashita2, Naoyuki Yasui3, Shigeki Takago3, Minoru Hiramatsu4 and Teruto Kanadani5
1Department of Mechanical Systems, Faculty of Engineering, Hiroshima Institute of Technology, Hiroshima 731-5193
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.
hydrogen embrittlement, high strength steel, three-point bending test, zinc electroplating, zinc-nickel alloy electroplating
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