Influence of later-dissolved oxygen on microstructural changes in oxide films formed on Alloy 690TT in hydrogenated primary water

Alloy 690 was first oxidized in hydrogenated primary water containing B and Li at 325 degrees C and 15.6 MPa for 30 days, and then, half of the samples were continuously immersed in the oxygenated primary water for 30 days. Oxide scales were analyzed using various methods. Results showed that the later-dissolved oxygen promoted the dissolution of protective Cr-rich oxides formed in the hydrogenated primary water by increasing their corrosion potential. The newly grown oxide film in the oxygenated primary water was loose and Ni-rich; further, its non-protective character increased the inner corrosion rate. (C) 2015 Elsevier Ltd. All rights reserved.