A new model for studing the evaporation behavior of alloy elements in DD98M alloy during electron beam smelting

As a new refining technology, the electron beam smelting has been widely used for alloy purification due to its advantages in removing volatile impurities and non-metallic inclusions. However, the evaporation of alloy elements during the smelting process leads to uncontrollable alloy composition. In order to predict the volatilization behavior of the alloy elements, various theoretical models have been proposed. These models can be well applied to binary or ternary alloys, but could hardly predict the volatilization behavior in multicomponent alloys due to the complex interaction of alloy elements. In this paper, a new model is established and verified for investigating the elemental volatilization during electron beam smelting of DD98 M alloy. The results show that the smelting powers of 12 kW, 14 kW and 16 kW result in the average melt surface temperatures of 1870 K, 1901 K and 1911 K. The O and N in the DD98 M alloy can be reduced by 70.6% and 55.0% when smelted for 10 min with power of 12 kW. Using the modified model, the theoretically calculated alloy compositions agree well with the experimentally measured values in all temperature ranges. The model shows instructive significance for vacuum refining of DD98 M alloy and other nickel-based superalloys.