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The effectiveness of zinc on the electrochemical behavior and oxide film formation of a 30% cold forged Alloy 690 exposed to high-temperature borated and lithiated water was investigated. The morphology and chemical composition of the formed oxide films with and without zinc injection were analyzed and compared by TEM–EDS and XPS techniques. Zinc clearly improved the electrochemical corrosion parameters of the alloy. Cathodic polarization improved the passivation of the alloy especially in presence of zinc. It was also found that actual zinc concentrations higher than 10 ppb is needed to observe a significant improvement in the corrosion resistance of the alloy in the pressurized water reactor operating conditions. Finally, further investigations of the effect of cold work on the high–temperature electrochemical performance of Alloy 690 and other iron and nickel based alloys in zinc injected solutions is recommended for the future studies. • Zinc improved the corrosion resistance of the cold forged Alloy 690 at primary coolant. • The zinc modified oxide spinels were 20% up to 50% thinner than the unmodified oxides. • The actual zinc concentrations need to be determined at high temperatures. • Cathodic polarization improved the electrochemical performance of the alloy at high temperatures. [ABSTRACT FROM AUTHOR]

The effects of mechanical grinding/polishing, surface roughness, and near-surface deformation on the electrochemical corrosion behavior of thermally treated (TT) Alloy 690 were studied in a sodium chloride solution. The X-ray photoelectron spectroscopy and transmission electron microscopy analyses revealed that mechanical grinding/polishing can change the ratio of the elements at the surface of the as-received Alloy 690TT specimen by removing its Cr-rich outer layer and causing deformation at the near-surface microstructure, something which has a direct impact on the rate of the oxygen reduction reaction (ORR), the pitting potential ( Epit), and the corrosion potential ( Ecorr) of Alloy 690TT. It was observed that the ratio of Cr in the surface is a significant factor that controls the rate of the ORR and the corrosion parameters such as Ecorr. Higher amounts of Cr at the surface accelerate the ORR. The near-surface deformation shifts the Epit values towards less positive potentials. It was also found that due to the different near-surface chemical composition of the as-received Alloy 690TT specimen compared with the ground and the polished specimens, the surface roughness parameters do not have a regular correlation with the rate of the ORR and the values of the Ecorr and the Epit. Only the passive current density increases when the surface roughness is increased. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]