Corrosion Behavior of 13％Cr Steels in Supercritical CO₂ Environments

Abstract

In this paper, the effect of supercritical CO₂ on corrosion behavior of stainless steels, mainly 13%Cr steels, was reviewed. Corrosion rate of 13%Cr steels in supercritical CO₂ was similar to or less than that in gas CO₂. When the pressure of supercritical CO₂ became higher than 20MPa, pitting corrosion was more likely to occur in the steels. Under the supercritical CO₂ including 45kPa oxygen, crevice corrosion of 13%Cr steels was recognized. When oxygen partial pressure reduced to 4.5kPa in supercritical CO₂, no crevice corrosion was recognized in Steel B which was a low C steel with Mo addition. Steel B showed better corrosion resistance than Steel A which did not contain Mo, in all tested conditions, not only CO₂ gas conditions but also critical CO₂ conditions. Published papers related to effects of impurities such as NO₂, SO₂ and etc. on corrosion resistance of stainless steels and estimation of phase behavior of supercritical CO₂ were reviewed and summarized.