51313-02504-Effect of Temperature on Crevice Corrosion Susceptibility of Nickel Alloys for Nuclear Repositories

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Product Number: 51313-02504-SG

ISBN: 02504 2013 CP

Author: Martin Rodriguez

Publication Date: 2013

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Nickel based alloys bearing chromium and molybdenum offer an outstanding corrosion resistance in a wide variety of highly corrosive environments. This versatility is due to the beneficial effects of Cr and Mo in oxidizing and non-oxidizing conditions respectively. Nickel based alloys such as N06625 (Ni-21Cr-9Mo-3.7(Nb+Ta)) N06022 (Ni-22Cr-13Mo-3W) N07022 (Ni-21Cr-17Mo) and N10362 (Ni-22Mo-13Cr) are considered among candidates for engineered barrier of nuclear repositories. The Argentinean National Atomic Energy Commission (CNEA) is in charge of the nuclear waste management in Argentina. This involves the projection building and operation of the high-level nuclear repository. Actual research involves the assessment of different materials potentially used as engineered barriers for the repository system. Nickel based alloys stainless steels carbon steels copper etc. are considered for this purpose. Degradation modes include general corrosion pitting corrosion crevice corrosion environmentally assisted cracking etc. In the present work the crevice corrosion resistance of selected nickel based alloys is evaluated.
The repassivation potential is the parameter associated to the crevice corrosion resistance of a material in certain environmental conditions. The crevice corrosion repassivation potential of the tested alloys was determined by the Potentiodynamic-Galvanostatic-Potentiodynamic (PD-GS-PD) method. The four alloys were tested in the mill annealed condition in chloride solutions at different temperatures. The aim of the present work was to compare the crevice corrosion resistance of the tested alloys assessing the effect of temperature on the chloride-induced crevice corrosion. Tests were performed in chloride solutions at temperatures ranging from 30ºC to 100ºC. For each alloy the repassivation potential linearly decreased with the temperature. The crevice corrosion resistance of the alloys increased with the PREN (Pitting Resistance Equivalent Number).
The possibility of reaching a critical potential below which crevice corrosion does not occur at any temperature and chloride concentration is discussed.
Crevice corrosion was observed at temperatures lower than the literature reported critical crevice temperature for each alloy.