Environmentally Assisted Cracking (EAC) can cause increases in fatigue crack growth rates of 40 to 100 tiems the rate in air for low alloy steels. The increased rates can lead to very large predicted crack growth. EAC is activated by a critical level of dissolved sulfides at the crack tip. Sulfiee includsions (MnS) in the steel produce corrosive sul;fides in solution following exposure by a growing crack. In sitagnant, low oxygen water conditions considered here, diffusion is the dominant mass transport mechanism acting to change the sulfide concentration within the crack.
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