Effects of Cr Content and the Addition of Cr₂O₇^2-Ion on Corrosion Resistance of Stainless Steel in Nitric Acid Solutions

Abstract

A nitric acid solution containing Cr₂O₇^2-ion is used for a corrosion test which simulates the condition in a nuclear fuel reprocessing plant. As the effect of Cr content on the corrosion resistance of stainless steel is not yet fully understood in that solution, the effects of Cr content in an alloy and that of Cr₂O₇^2-ion in nitric acid on the corrosion rate were studied by using electro-chemical measurements, The increase of Cr content reduced the general corrosion rate in nitric acid solution without Cr₂O₇^2-ion, however it increased that in nitric acid solution containing Cr₂O₇^2-ion, It is considered that the reversal of the Cr content dependency is due to a rise of the corrosion potential caused by addition of Cr₂O₇^2-ion to the potential region where a high Cr alloy shows higher anodic dissolution rate than a low Cr content alloy.