Fundamental Study On Process Of Mn18Cr18N Retaining Ring Steel

Mn18Cr18N, as an excellent high nitrogen steel, has high strength and high stress corrosion resistance. The study and production of Mn18Cr18N cause the attention of reasearchers at home and abroad. The study of theoretical basis and material property has a significant importance in promoting the production of retaining ring steel in our country.Based on the nature of the rules of reference solution, the thermodynamic model of nitrogen solution in liquid steel is established. The influence of different factors on the nitrogen solubility is analyzed. Meanwhile, the solution model is verified with the actual results. The limiting factors in the kinetics study are analyzed, which will guide the practical experiments. The study of segregation during the solidification of steel provides the theory basis to prevent precipitation of nitrogen during solidification.Nitriding experiments by nitrogen and nitride alloy are done separately under the normal pressure. The best nitriding result is obtained by using nitrogen and nitride alloy. The experimental results indicate that best smelting temperature of nitriding by nitrogen is 1650?. the best smelting temperature of nitriding by nitride alloy is 1550?.By means of vacuum induction furnace + nitrogen protection electroslag remelting duplex process preparation, more than 0.63% of the nitrogen content Mn18Cr18N steel was produced. The quality of Mn18Cr18N steel in ESR process is studied with different remelting parameters.Procast software is adopted for the purpose of simulating Mn18Cr18N steel microstructure in ESR process. The influence of different process parameters on microstructure morphology, grain number, grain average radius and the secondary dendrite spacing are studied. The best parameters of solidification are obtained, which increases the grain number by 30.58%, reduces the average grain size reduced 38.39%, decreases the secondary dendrite spacing by 21.34%. It will has great significance in the actual production of Mn18Cr18N steel.The hot working performance of Mn18Cr18N ESR ingot is analyzed, including tensile mechanical properties in high temperature and room temperature, tensile fracture morphology, fracture mechanism analysis and thermoplastic property in high temperature. The result indicates that thermoplastic property of Mn18Cr18N is higher within the range of 850??950? and 1100??1250? than 950??1050?. The hot working temperature should be controlled between 1100??1250? to avoid ferrite and fracture of material.