ELECTRON BEAM MELTING METHOD FOR REFRACTORY HIGH-MELTING-TEMPERATURE METAL MATERIAL

摘要

PURPOSE:To efficiently remove impurities in high-melting-temperature metal materials by evacuating the inside of a melting furnace to a specific degree of vacuum and then carrying out electron beam melting while maintaining the pressure inside the furnace at a specific value by blowing H2 gas into the furnace. CONSTITUTION:A raw material is supplied from a hopper 3 into a water-cooled vessel 4 in an electron beam melting apparatus, and the inside of a sealed case 1 is evacuated until a pressure of 1X10-6-1X10-4Torr is reached. Subsequently, H2 gas is supplied by means of a flow regulating valve 11, and electron beam melting is carried out while controlling the amount of evacuation and the amount of H2 gas supplied so that the pressure in the furnace is maintained at (nXP0)-(1X10-2)Torr [where the symbol (n) stands for 3-8 and P0 means ultimate pressure at the time of the above evacuation, respectively]. By this method, S, Si, Fe, metal oxides, etc., not to mention gases, such as O2 and N2, contained in high-melting-temperature metals, such as V, Nb, and Mo, and alloys composed principally of these high-melting-temperature metals, in particular, can be efficiently removed and, as a result, the high-purity and high- melting-temperature materials can be obtained.