The Effect of the Transport Properties of the Crack Solution on Corrosion Fatigue Crack Growth Rates of Steel in Seawater

摘要

Model calculations have been conducted to predict the behaviour of the corrosion fatigue, CF, crack growth rate, dA/dn, in steel under anodic polarisation in deaerated seawater. The model takes into account the special solute transport properties of the crack solution arising from the 'flow enhanced diffusion' (FED) effect. This effect has been investigated by means of computer simulation of the movement of diffusing particles in the crack solution during cyclic flow. Near the tip, solute transport is found to occur essentially by normal diffusion, while in the remaining part of the crack FED is the dominant mechanism. Predictions of the behaviour of dA /dn are in good agreement with reported experimental results and the model explains the anomalous high crack growth rates measured in 'chemically short' cracks.