表層超細粒鋼板の海水中疲労強度とその評価(その4)

概要

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In this paper, fatigue crack propagation tests in air and artificial sea water enviroments were conducted in order to grasp the character of fatigue crack propagation in thickness direction of SUF steel plate. Observations on the fracture surfaces were also made with SEM to investigate the striations. As a result of this study, the following conclusions were obtained: (1) The rate of fatigue crack propagation of SUF steel plate in artificial sea water is more than twice as high as that in air, when ΔK is over 22〜25MPa√<m> (70〜80kgf/mm^<3/2>) on the surface layer, and ΔK is over about 16MPa√<m> (50kgf/mm^<3/2>) on the mid-section. (2) The rate of fatigue crack propagation of the surface layer is obviously lower than that of the mid-section, when ΔK is under about 19MPa√<m> (60kgf/mm^<3/2>) in air, and ΔK is under about 28MPa√<m> (90kgf/mm^<3/2>) in artificial sea water. (3) The relations between the intervals of the striations observed on the fracture surfaces and ΔK are equivalent to those between the rate of fatigue crack propagation obtained from the results of fatigue crack propagation tests and ΔK, when ΔK is large.
社団法人日本船舶海洋工学会の論文
2000-09-04