Carburization-induced passivity of 316 L austenitic stainless steel

A low-temperature (450-500 degrees C) gas-phase process for introducing substantial amounts of carbon, without carbide formation, into 316L austenitic stainless steel has been developed. This process, termed low-temperature colossal supersaturation (LTCSS), provides surface carbon concentration as high as 14 atom % and dramatically improves the localized corrosion resistance of 316L austenitic stainless steel in ambient temperature seawater. In particular, the LTCSS-treated steel increases the seawater breakdown potential by more than 600 mV. This result is remarkable, as traditional carburization methods have historically decreased the corrosion resistance of stainless steels. (c) 2007 The Electrochemical Society.