Deoxidation thermodynamic of electroslag remelting 304NG stainless steel

Based on the ion and molecule coexistence theory(IMCT) and the Wagner-Chipman model, the deoxidation thermodynamics of the CaF2-Al2O3-CaO-MgO-SiO2 slag system used for the drawing-ingot-type electroslag remelting of 304NG stainless steel was studied. The effects of different deoxidation systems on the mass fractions of O, Al and Si in steel, as well as FeO in slag were analyzed. The results show that under the condition of no deoxidizer, Al and Si in steel are successively oxidized by FeO in slag, resulting in an oxidation rate of 61.3% for Al and 9.7% for Si at equilibrium, while O increases by 75.1%. When Al, CaSi and Al+CaSi are used for deoxidation, the mass fraction of FeO in the slag can be reduced to 0.12%, 0.24% and 0.10%, respectively. Compared with using Al and CaSi individually, the Al+CaSi composite deoxidizer not only exhibits a superior ability to control the oxygen potential, but also demonstrates a smaller variation range of Al and Si relative to the initial mass fraction of the electrode. In the electroslag remelting process, the mass fraction of O in steel is determined by Al−O balance. © 2023 Central South University of Technology. All rights reserved.