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Article – Journal of Advanced Electrochemistry

Journal of Advanced Electrochemistry, Volume 2,Issue 4,2016 Pages 117-120


Corrosion Behavior of 18Cr-18Mn Hot-Forged and Plasma-Nitrided Steel
R.R. Hernandez, A.Torres-Islas*, S. Serna, A. Bedolla, A. Molina, J. Colin, H. Martinez

An 18Cr-18Mn alloy steel used for manufacturing retaining rings in the turbogenerator energy industry, were corrosion evaluated. This steel is forged and nitrided to increase its corrosion and mechanical resistance. In this study, after the hot-forging process, nitrogen was diffused into the steel by plasma nitriding. The corrosion behavior and electrochemical stress corrosion cracking (SCC) susceptibility of the steel before and after nitriding was characterized by potentiodynamic polarization, electrochemical impedance spectroscopy, and electrochemical noise measurements. The forged, nitrided steel exhibited better corrosion resistance than the as-received steel and the steel subjected only to nitriding or forging; these results were attributed to the presence of surface nitrides, steel chemical composition, chemical stability of the corrosion products, structural state of the passive film, and ability to prevent diffusion of metal ions. Furthermore, the nitrides tended to prevent corrosion pit growth.



Keywords: 18Cr-18Mn Steel; Plasma Nitriding; Hot Forging; Corrosion Resistance;