Influence Of Surface Treatment Of Chromium-Nickel Stainless Steels On Corrosion Resistance In Nacl Solutions

Corrosion behaviour of plasma carbonitrided stainless steels 304L, 316L, 211 and S32404 was studied. The carbonitriding process was performed using the plasma assisted chemical vapour deposition technique in MWPACVD (Microwave Chemical Wapour Deposition) system (2,45 GHz, 350 W). During the treatment gaseous mixtures containing CH4 and N-2 were introduced to the reactor under low pressure (0,8 Tr) at low temperature of 400 degrees C. The steel surface structure was analysed by X-ray photoelectron spectroscopy (XPS). The corrosion behaviour of the samples was determined basing on polarisation (LSV) curves measured in an aqueous solution of sodium chloride (1 i 3% NaCl). The surfaces modified by carbonitriding showed a better ability to passivation compared to the unmodified ones. Moreover, a higher corrosion resistance to pitting corrosion was observed for the 0H18N21Si5M steel.