Evaporation behavior of Ni, Cr and Fe in Inconel 718 superalloy during electron beam smelting

The electron beam smelting (EBS) technology was employed in refining the Inconel 718 superalloy for the first time. The evaporation behavior of Ni, Cr and Fe in Inconel 718 superalloy during the smelting process was investigated, which would facilitate the controlling of alloy composition. The Inconel 718 superalloy was smelted by three groups of different power in the experiments; the volatile regularity of Ni, Cr and Fe in Inconel 718 superalloy was studied theoretically by calculating the element volatile of Ni-Cr-Fe ternary alloy. The experimental results show that the mole fraction of Fe remains constant before and after the experiment, while for Ni and Cr, the mole fraction are found to be above and below the level of raw material respectively. The smelting power of 9 kW, 10.5 kW and 12 kW correspond to the average temperatures of 1530.1 K, 1552.4 K and 1553.5 K, respectively, for the melt surface. The theoretical calculation and experimental results of Ni, Cr and Fe mass loss rates are in good agreement, the model employed in calculation shows its significance in theoretical guidance for the preparation of Inconel 718 superalloy and other nickel based superalloys.