Numerical Simulation of the Denitrification Reaction of INCONEL 718 Superalloy During Vacuum Induction Melting

The nitrogen content of INCONEL 718 superalloy is a key factor in determining its performance. Vacuum induction melting (VIM) is the main stage of nitrogen removal in the production of superalloys, where the nitrogen content of the alloy should be minimized. In this work, a mathematical model of electromagnetic thermal flow mass-transfer coupling was developed to investigate the feature of the electromagnetic force, heat transfer, fluid flow, and nitrogen distribution in the melt pool during VIM, which was used to analyze the effect of electromagnetic stirring on the denitrification reaction by means of finite element simulation. The effects of current intensity and pressure on the denitrification reaction during VIM were studied. Moreover, the model developed in this article was validated. The results indicated that electromagnetic stirring accelerated the mass transfer rate of nitrogen and had a significant effect on the distribution of nitrogen content in the melt pool of superalloys during VIM. Increasing the current intensity and reducing the pressure will promote denitrification of superalloys. The model validation results showed that the numerical simulation results were less inaccurate than traditional theoretical calculations, so the model developed in this article can more accurately predict the variation in nitrogen content of INCONEL 718 superalloy.