The stability of a corrosion pit is directly related to the pit solution chemistry. In order to know the stability of a meastable pit, the product of corrosion current density and diffusion depth (pit radius for an open hemisphere pit) is compared to the stability product obtained from the artificial pit electrode results. In this paper the stability of a metastable pit recorded on a 904L stainless at 54 8C (28C below the alloy CPT) is investigated. Assuming the geometry result of such a transient is an open hemisphere, pick current density and pit radius were calculated from Faraday’s equation and then pit stability product (i
a) was calculated. This value was compared with the product of i
a associated with the pit solution chemistries (critical, saturation and supersaturation concentrations) which were obtained from the investigation on artificial pit electrode at the same temperature. SEM investigations on pit cavity generated from large metastable pit current transients with the stability product greater than the stability product associated with supersaturation concentration of pit environment proves that measured pit solution chemistry from artificial pit electrode is a reliable step for evaluation of pit stability.

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