The denitrification behavior during electron beam smelting of FGH4096 alloy

Abstract

The FGH4096 alloy was prepared by electron beam smelting, and the effect of electron beam smelting parameters on the denitrification behavior were studied. The denitrification thermodynamics and kinetic mechanisms were analyzed. The results show that the nitrogen content in the FGH4096 alloy can be reduced from 17 ppmw to less than 1 ppmw after electron beam smelting. Increasing the smelting power or prolonging the smelting time will promote the removal of nitrogen effectively. The activity coefficients of nitrogen in the melt under different smelting temperatures were obtained. The solid solubility of nitrogen in the alloy decreases gradually as the vacuum increases, and increases gradually as the melt temperature increases, but a more significant effect is observed for the vacuum. The inclusions in the near-surface area of the melt can be removed by dissolution, and the inclusion particles floating above the melt level can be decomposed under the action of electron beam bombardment. The rate constant for the nitrogen removal process increases with the increase of melt temperature. The removal of nitrogen tends to be controlled by the second-order reaction, the first-order reaction and the 1.5th-order reaction, respectively, when the smelting power varies from 9 kW to 15 kW.