Effect Of Nitrogen On Corrosion Resistance Of Nickel Austenitic Stainless Steel

Nickel-saving austenitic stainless steel has excellent corrosion resistance,making scholars at home and abroad attach great importance to its research and development.Nickel-saving austenitic stainless steel has a high nickel alloy content,and China relative nickel resources Lack.Therefore,at present,China urgently needs to develop a resource-saving high-value-added nickel-saving nitrogen-containing austenitic stainless steel.Nowadays,by adding a large amount of nitrogen and manganese to austenitic stainless steel,the development of new nickel-saving nitrogen-containing austenitic stainless steel is a research hotspot.The corrosion resistance of this type of nickel-saving nitrogen-containing austenitic stainless steel is of great significance for the development of nickel-saving nitrogen-containing austenitic stainless steel.In this paper,the thermodynamic software Thermo-Cala,chemical immersion method,anodic polarization method,electrochemical impedance method and other corrosion methods,as well as metallographic microscope and scanning electron microscope auxiliary methods,were used to uniformly corrode and crystallize nickel-containing nitrogen-containing austenitic stainless steel.The inter-corrosion and electrochemical corrosion properties were studied.The calculation results of thermodynamic software Thermo-cala show that the experimental steel as a whole is an austenite phase at 650℃,and there are also M₂₃C₆ and Cr₂N phases.The existence of these phases has a significant effect on the corrosion resistance of the experimental steel.As the time increases,the proportion of precipitates also gradually rises.Here,the temperature sensitization process is controlled as much as possible to 5 min to prevent intergranular corrosion.The intergranular corrosion experiments after sensitizing the nickel-saving austenitic stainless steel found that the corrosion performance is also affected by the nitrogen content.The results of different sensitization treatment times at 650°C showed that the corrosion rate of high-nitrogen austenitic stainless steel was low.Nitrogen austenitic stainless steel is twice as fast and the corrosion rate at 2.5 min is 2.5 times that of 5 min.This result is formed because the high content of nitrogen improves the stability and compactness of the passivation film at the grain boundaries and reduces the precipitation of precipitates at the grain boundaries.Propensity.Compared with 5min and 300min,the incubation time of the 5min precipitate is not enough,and the precipitation rate of the precipitate is low,so it shows good corrosion resistance.Through electrochemical corrosion experiments after sensitizing nickel-saving austenitic stainless steel,it is found that the capacitive impedance arc radii of high-nitrogen steel and low-nitrogen steel at 650℃both increase and then decrease.The capacitive arc radius of austenitic stainless steel varies greatly with sensitization treatment time.The maximum capacitive arc radius is 5 min,which decreases with time.The stainless steel polarization curve shows that the high nitrogen austenitic stainless steel and low nitrogen austenitic nitrogen steel show the same trend over time.The corrosion potential（0.62537V）of the high nitrogen steel is significantly higher than that of the low nitrogen steel at the same time.（0.59747V）corrosion potential,so the corrosion resistance of high nitrogen steel is better than low nitrogen steel.This result is formed because the high nitrogen content in the steel can significantly improve the stability of the passivation film at the grain boundaries.Conducive to the stability of the inert passivation film,to prevent continued corrosion of the corrosive medium.