Mechanistic study of Cr effect on FAC rate of carbon steel

Combined effects of Cr content and pH on flow accelerated corrosion (FAC) of carbon steels have been formulated and their relation to oxide scale characteristics based on detailed oxide layer characterizations using transmission electron microscope with X-ray analyzer have been discussed. It has been possible that the solubility of Fe3O4 was enhanced locally by the high H2 partial pressure which results from the high corrosion rate. Cr concentration is highest at top surface of oxide layer, and that decrease from surface to oxide/metal interface gradually. It has been suggested that Cr enrichment stabilize oxide layer (decrease solubility of oxide layer), as a result, FAC suppressed. (author)