Removal of impurity elements in EB-CHR melting process of metallic alloys

Electron beam cold hearth refining (EB-CHR) of Ni, Ti-based alloys and refractory metal (Nb, Mo, Ta and W) was performed to examine the refining effect and its ability to produce homogeneous materials in the 2000 kW EB-CHR furnances. (1) Behavior of gaseous elements in the refractory metals was discussed with taking the volatile parameter, Vp, into the consideration. (2) The evaporation rate of impurities in the refractory metals was in good agreement with actual vapor pressure from the viewpoint of pressure ratio, P_i/P_Nb, P_i/P_Ta. (3) The evaporation rate of the alloying elements in Inconel 718 was discussed in terms of the following properties: vapor pressure, atomic mass, and molten temperature, it was in good agreement with calculated vapor pressure. (4) Actual yielding of aluminum in Ti-6A1-4V alloys was determined by the rate of linear reaction rate, which was discussed in terms of the following properties: aluminum contents of electrode, melting rate, and molten temperature. It was in good agreement with the calculated yielding of aluminum.