A study of the mechanism of corrosion of some ferritic steels in high-pressure carbon dioxide with the aid of oxygen-18 as a tracer - III. Fe-9% Cr-1 % Mo-0.26 % Si

The oxidation mechanism of a commercial Fe-9% Cr steel in high-pressure (4.1 MPa) carbon dioxide at 913 K have been investigated with the aid of charged-particle nuclear techniques and 18 O as a tracer. Duplex and multilayered oxide‒scales were examined. Both types of scale grew at the oxide‒gas interface. Substantial growth occurred in the inner half of the inner layer on the specimen with the duplex scale; very little growth occurred within the inner layer of the multilayered scale. A possible oxidation sequence which could account for the 18 O distributions is proposed.