LOCALIZED CORROSION CHARACTERISTICS OF ULTRA HIGH NITROGEN-BEARING AUSTENITIC STAINLESS STEELS IN ARTIFICIAL SEAWATER

摘要

Localized corrosion resistance of nitrogen-bearing austenitic stainless steels of up to 1.2 mass% was studied electrochemically, to produce resource-saving type stainless steel with excellent localized corrosion resistance. The two key technologies used were high nitrogen alloying and purification of the material itself. It was shown that ultra high nitrogen-bearing stainless steels have superior crevice corrosion resistance and molybdenum effectively improved crevice corrosion resistance. There clearly was a positive correlation between crevice corrosion resistance equivalent and crevice corrosion potential for all samples tested. No crevice corrosion was recognized in 1%N-2%Mo steel and 1.2%N-4%Mo steels at any potential below 0.8V vs.SCE. Surface analysis were carried out by means of ESCA. The role of nitrogen at the surface was also discussed.