人工海水中の高張力鋼HT60の腐食疲労き裂進展特性

概要

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Corrosion fatigue crack growth and near-threshold characteristics of high tensile strength steel HT 60 (σ_B = 669 MPa) were investigated. Compact specimens were exposed to synthetic sea water under ΔK-decreasing and ΔK-increasing conditions at two stress ratios (R = 0.1 and 0.7) and at a cyclic frequency of 5 Hz. The results obtained were compared with that of high strength steel AISI 4340 (σ_B = 1 209 and 1 695 MPa) and are summarized as follows : (1) A da/dN-ΔK_<eff> relation in air can give a conservative estimation of da/dN-ΔK relations in sea water. (2) In the case of high R, however, crack growth acceleration at high ΔK regions appears to be controlled by the stress-assisted dissolution. (3) The crack opening stress intensity factor K_<op> detected by the back-face-strain method is the result of crack surface contact with the corrosion products and gives an overestimation of K_<op> at the crack tip.
一般社団法人日本機械学会の論文
1987-12-25