高強度鋼の海洋環境腐食疲労き裂進展下限界特性の評価

概要

論文の詳細を見る
Near-threshold corrosion fatigue crack growth characteristics and crack closure of high strength steels AISI 4340 with two yield strengths (σ_Y=1 446 and 1 089 MPa) below K_<ISCC> were investigated. Compact specimens were exposed to synthetic seawater under ΔK-decreasing conditions at two stress ratio (R=0.1 and 0.7) and at a cyclic frequency of 5 Hz. The results obtained are summarized as follows : (1) A da/dN-ΔK_<eff> relation in air can give a conservative estimation of da/dN-ΔK relations in seawater. (2) Corrosion products formed within the crack are FeOOH and Fe_3O_4 and exist behind the crack tip. (3) The crack opening stress intensity factor K_<op> detected by the back-face-strain method is result of crack surface contact with the corrosion products and gives overestimation of K_<op> at the crack tip.
社団法人日本機械学会の論文
1986-08-25