Microstructure and Corrosion Properties 0Cr21Mn17Mo2N0.8 High Nitrogen Austenitic Stainless Steel

The high nitrogen stainless steel with solid solution heat treatment after forging was austenitized completely. The microstructure of the alloys were observed by OPM, SEM and EDS. The mechanical properties were analyzed by tensile test and impact test. In addition, the corrosion test of high nitrogen austenitic stainless steel, 304 stainless steel and 316L stainless steel were conducted in the environment of highly purified nitrogen gas in the autoclave, and the deionized water is used to make 10000mg/L sodium chloride solution. The corrosion depth was studied by laser scanning confocal microscope. The experimental results showed that the addition of nitrogen improves greatly the mechanical properties of stainless steel. Otherwise, three kinds of stainless steel caused pitting in sodium chloride solution, because the passive film of stainless steel was destroyed due to the permeation of the chloride ion. Moreover, the corrosion rate of high nitrogen austenitic stainless steel is much lower than that of the 304 and 316L stainless steel. So the corrosion resistance of high nitrogen steel is much better. On account of the chemical interaction between nitrogen and molybdenum, it can prevent the surface from forming high current density and decrease the pitting tendency of stainless steel. The result expanded greatly the application of high nitrogen stainless steel in the field of corrosion. (paper)