造船用鋼板の疲労亀裂進展と微細組織 : 高硫化水素原油中における造船用鋼板の疲労亀裂進展挙動(第2報)

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The possibility of decreasing corrosion fatigue crack propagation rate accelerated by hydrogen embrittlement is discussed in this paper in order to develop a new ship structural steel plate with the resistance to corrosion fatigue in sour crude oil. Effect of steel microstructure on the crack propagation rate has been investigated under cathodic hydrogen charging. The crack propagation rate of the steel with bainite microstructure was lower than that of the steels with ferrite-pearlite banded microstructure, ferrite-bainite and ferrite with dispersed pearlite in the ΔK of less than 20〜30Pa√lt;m>. The difference of the crack propagation rate decreased with the increase in ΔK or hydrogen permeation coefficient. The effect of microstructure was mainly discussed from a viewpoint of propagation of microcrack due to hydrogen embrittlement in these steels, based on the slow strain rate test results under cathodic hydrogen charging. It was found that microcracks in the bainite steel stopped at grain boundaries or bainite interfaces. On the other hand, there was very few microcrack in the steels with other micrstructures such as ferrite. Considering these results, it was concluded that the bainite microstructure can reduce the propagation rate of fatigue crack accelerated by hydrogen embrittlement. The detailed mechanism should be studied in future.R3001000
社団法人日本船舶海洋工学会の論文