This paper presents the results from the analysis of the steam generator tubes exposed to a mixed amine chemistry in a refreshed autoclave at 285C. A major objective of this study is to gain a better understanding of the relative corrosion behaviour of these alloys. The effect of pre-treatments, such as prior oxidation and mechanical stress, on the oxidation behaviour is also included in this paper. Preliminary results indicate that the oxides formed after long exposures have a compact, extremely fine-grained layer on the metal surface. In addition to the compact oxide, coarse crystallites were seen on the top of the compact layer and these were determined to be transported from else where in the system. The significance of these and other results will be discussed in the context of expectations for the long-term corrosion behaviour.