Effects of C and N on Corrosion Resistance of High Cr Alloys in CO_2 and H_2S Environments.

摘要

In CO_2 environments, corrosion rate of 12-13% Cr alloys depends on carbon and nitrogenrncontents, because C and N form carbides and nitrides reducing Cr content in matrix. From chemical analysis of extracted residuals, a new index Cr_(eff) accounting N is proposed as following.rnCr_(eff) = Cr- 10(C+N)rnGood correlations were found between Cr_(eff) and corrosion rate of high Cr alloys in CO_2rnenvironment. Results of polarization measurements indicate that C and N mainly control anodic behavior in high pH solutions, In NACE solution saturated with 1 atm H_2S and low pH number, thernprecipitation of carbides and nitrides accelerated cathodic reaction resulting in high corrosion rate