Abstract
A new duplex stainless steel, S32101, was chosen in this work for investigation of the corrosion properties in an environment corresponding to concrete pore solutions. The new duplex stainless steel was developed for general use and with high mechanical strength. Furthermore, the steel has a chemical composition corresponding to a corrosion resistance similar to that of type 304 or better. To balance the ferritic-austenitic microstructure nitrogen and manganese are used instead of expensive nickel. In this work a general screening of the corrosion resistance of this steel grade is presented. First, this includes results from a test program regarding uniform corrosion, where a number of steel grades in addition to the new duplex steel grade were tested according to a test program specified by the Materials Technology Institute, MTI and standardized as ASTM G 157. Then, results from laboratory corrosion tests regarding pitting corrosion, intergranular corrosion and stress corrosion cracking were compared for the new duplex steel to the standard austenitic stainless steels. Finally, the suitability of using this new duplex steel as reinforcements in concrete was investigated. For this purpose, rebars of UNS S32101 were compared with standard stainless steels, using electrochemical tests to screen the corrosion resistance. The test solutions were artificial solutions corresponding in alkalinity and chloride contents to concrete pore solutions. High corrosion resistance was obtained for the new duplex stainless steel in these solutions. These results were also discussed and compared with a field test carried out in a concrete bridges-survey.
