各種高張力鋼の海水中での腐食疲れき裂伝播挙動

概要

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Fatigue crack growth rates were obtained in air at 16.7Hz, (da/dN)_<air>, and those in sea water at 0.167 Hz, (da/dN)_<cor>, for HT80, HY140, HY180, HY240, HP9-4-20, PH13-8Mo, and 18Ni(200) maraging steels. Stress ratios, R, of 0.10 and 0.50 were used. The ratio of (da/dN)_<cor>/(da/dN)_<air>, r_<0.167Hz>, were used as the degree of the effect of sea water on fatigue crack growth. The following results are obtained : (1) The value of r_<0.167Hz> was lower in HY140 tempered at 615℃ and HP9-4-20 steels. (2) The maximum value of r_<0.167Hz> was obtained at ⊿K=50 to 100kg/mm^<3/2> for R=0.10 in all steels used. At ⊿K<20∿40kg/mm^<3/2> and ⊿K>250kg/mm^<3/2>, no effect of sea water on fatigue crack growth rate was obtained. (3) The value of r_<0.167Hz> depended on K_<max> and ⊿K at lower and depended on ⊿K at higher crack growth rate. The maximum value of r_<0.167Hz> depended on K_<max>. (4) A positive interrelation was obtained between r_<0.167Hz> and area fraction of brittle fracture in 18Ni (200) maraging steel.
社団法人日本鉄鋼協会の論文
1980-10-01