Corrosion Mechanism of a Plasma Nitriding-Treated Alloy

Plasma nitriding of an alloy is a low-temperature chemical-thermal treatment technology. The nitrided layer exhibits a high density, corrosive, wear, and fatigue resistance, being low-deformable. A 12Cr2NiWVA alloy was plasma-nitrided, and the corrosion mechanism of the nitrided layer at high temperature and pressure was studied. The effect of nitriding, heat treatment, fine grinding, and other technologies on corrosion was investigated. The composition of a corroded material was analyzed, and sectional hardness was microscopically examined. It is demonstrated that nitriding not only improved the wear resistance but also reduced the chromium content in the matrix, resulting in the reduction of the oxidation and corrosive resistance performances of the material. Fine grinding exerted an adverse effect on the wear and corrosive resistance. The varying distribution of temperatures during the heat treatment resulted in the nonuniformity of properties throughout the material after nitriding, followed by the growth of strains.