Study On The Effect Of Nitrogen Content On The Corrosion Resistance Of 316L Austenitic Stainless Steels

316L stainless steel is an austenitic stainless steel which contains molybdenum, and its corrosion resistance has been greatly improved compared with normal stainless steel. It has good general corrosion resistance and pitting corrosion resistance in different corrision medium and so that it is widely applied in the chemical, metallurgy, medical industry, and so on. Nitrogen has a positive effect on the performance of most steel products. In order to expand the application areas of 316L stainless steel, 316L stainless steel containing different nitrogen content was melted in high-frequency induction furnace at 1600℃and different nitrogen pressure. For the purpose of understanding the corrosion resistance, finding out the application environment ,and intensively analyzing the corrosion mechanism of 316L stainless steel with different nitrogen content, immersion test and Tafel polarization curve was used to test corrosion resistance of 316L stainless steel at different temperatures and in different corrosion medium. The corrosion mechanism of 316L stainless steel was also analyzed in this paper. What's more, we verified the corrosion process and results by A.C. impedance method. The surface morphology of corrision sample had been examed by SEM which is corroded in chloride ions.The experimental results were summaried as follows. (1) Nitrogen had a significant role in the improvement of corrosion resistance in stainless steel, and the best nitrogen content wais concerned to the type and concentration of corrosion medium. In this study, the experimental condition was that in the solution of 1mol/L H2SO4 and 0.5 mol/L NaCl, the optimum nitrogen content corresponding to the best of corrosion resistance was 0.5355%, while it's only 0.4650% in other corrosion solution. (2) The corrosion resistance of the sample decreased with the increase of the temperature. (3) The corrosion resistance of the sample decreased when the chloride ion concentration ranged from 1% to 5%, although it's improved a lot when chloride ion concentration increased to 10%. (4) With the increasing of pH value in the solution, the corrosion resistance of the sample decreased. (5) Under the different corrosion conditions of 20% H2SO4, NaOH and 10% HNO3, the best corrosion resistance for the same sample was in 10% HNO3 solution, while it is corroded heavily in NaOH solution. (6) When the nitrogen content of the sample is 0.0095% and 0.5885%, the sample was severely corroded and the residual element Cr on the surface was obviously higher. (7) It's more easily corroded in the phase boundary than around inclusions in steel.