13Cr系鋼の腐食環境下の低ΔK領域におけるき裂進展挙動

概要

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Corrosion fatigue crack growth tests in low ΔK region in 3%NaCl solution and in distilled water have been carried out on 13 Cr stainless steels at various stress ratios (R=-1.0, 0.1, 0.4, 0.8). The effect of frequency on corrosion fatigue crack growth in 3%NaCl solution was also investigated. The results are summarized as follows. (1) The corrosive environment studied here had little effect on crack growth rate in ΔK≥ΔK_<th> (ΔK_<th>: threshold value in air) for R= -1.0 and 0.1, but it slightly increased the crack growth rate for R≧0.4. (2) As critical crack growth rate dropped from (2〜5) ×10^<-10>m/cycle in air to (2〜5) ×10^<-11>m/ cycle in 3%NaCl, ΔK_<thCF>(ΔK_<thCF>: threshold value in corrosive environment) decreased 0.4 times (R=-1.0) to 0.6 times (R=0.1) of ΔK_<th>. ΔK_<thCF> in distilled water was (0.65〜0.70) time (R=-1.0 and R=0.1) of ΔK_<th>. (3) Corrosion pits often occurred at the corrosion fatigue crack tip in the region below da/dN=(2〜8.7) × 10^<-11>m/cycle. Therefore, the ΔK value required to reinitiate crack growth from those pits was about 1.5 times higher than that of ΔK_<thCF>. (4) The crack growth law derived previously by considering the effects of wave form and frequency was also found valid as the first approximation for the. materials tested.
社団法人日本材料学会の論文
1984-07-15