Surface Crack Growth Behavior of Pipeline Steel Under Disbonded Coating at Free Corrosion Potential in Near-Neutral pH Soil Environments

Crack growth behavior of Type 304 stainless steel in a simulated BWR water environment was investigated for the quantitative characterization of subcritical flaw growth in BWR piping systems. Crack propagation rates under corrosion fatigue and stress corrosion cracking were generated using compact specimens. The effects of several parameters on the rates were discussed. Furthermore, surface crack growth behavior was examined under different modes of cyclic loading, and results were discussed in comparison with compact specimen data. The corrosion fatigue crack propagation rates strongly depended on the frequency and the stress ratio. The rates became higher as the frequency lowered and the stress ratio increased. No effect from dissolved oxygen concentration and heat treatment of the steel was observed in tests, where transgranular cracking mainly took place. Stress corrosion cracking rate data indicated KISCC was above 15 MPa•m1/2. On the other hand, surface crack growth behavior included scattered crack propagation rates. However, the relationship between da/dN and ΔK was basically similar to that obtained in the compact specimens, except under given test conditions, where the acceleration for the crack growth rate at a crack tip on the panel surface was different from that at the deepest point.

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Low cycle fatigue properties and surface crack growth behavior under cyclic tension in 316L steel.

Journal of the Society of Materials Science Japan ◽

10.2472/jsms.38.1303 ◽

1989 ◽

Vol 38 (434) ◽

pp. 1303-1308 ◽

Cited By ~ 1

Author(s):

Yasuo OCHI ◽

Akira ISHII ◽

Shigemi K. SASAKI ◽

Nobuyoshi JIGU

Keyword(s):

Crack Growth ◽

Surface Crack ◽

Low Cycle Fatigue ◽

Growth Behavior ◽

Fatigue Properties ◽

Crack Growth Behavior ◽

Cycle Fatigue ◽

Cyclic Tension ◽

316L Steel ◽

Surface Crack Growth

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Environmental Effect of Crack Growth Rate of Pipeline Steel in Near-Neutral pH Soil Environments

2004 International Pipeline Conference, Volumes 1, 2, and 3 ◽

10.1115/ipc2004-0449 ◽

2004 ◽

Cited By ~ 4

Author(s):

Weixing Chen ◽

Robert Sutherby

Keyword(s):

Growth Rate ◽

Crack Growth Rate ◽

Crack Growth ◽

Soil Chemistry ◽

Pipeline Steel ◽

Crack Tip ◽

Growth Behavior ◽

Crack Growth Behavior ◽

General Corrosion ◽

Neutral Ph

The laboratory work reported here was initiated to determine whether different soils can be shown to give rise to different growth rate for a given pipeline steel. Two soil synthetic environments with different near neutral pH value were designed based on various soil chemistries collected near the pipeline in the field where near-neutral pH SCC was found. The crack growth behavior in both the environments were determined using compact tension specimen. The crack growth rate was in situ monitored by the potential drop system. It was found that soil chemistry has a profound effect on crack growth rate. Although it is insensitive to the soil chemistry and cyclic frequency, the crack growth rate in the high ΔK regime has been significantly enhanced in comparison with that in air. In the low ΔK regime, the growth rate is shown to have minor dependence on ΔK value but strong dependence on the testing environments. The observed crack growth behavior in different ΔK regimes and environments was related to the crack tip sharpness and crack crevice wideness as a result of corrosion and room temperature creep deformation. Soil solutions with low general corrosion rate are associated with a blunt crack tip and wide crack crevice, which would result in lower stress intensity at the crack tip and weaker crack closure effect, respectively. Similarly, a loading wave allowing shorter creep time on a given volume of material at the crack tip at high loading stress tends to produce a sharper crack tip and narrow crack crevice. These two factors have opposite effect on crack growth rate, and the observed crack growth rate reflects the combined effect of these two opposite factors.

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