| abstract |
A molten metal is subjected to a refining under a reduced pressure of vacuum or a low oxygen partial pressure atmosphere, and subsequently heated by means of inert gas plasma to re-refine. The metals to be processed are stainless steels, Ni-base alloys, Fe-Ni system alloys, electromagnetic steels, medium carbon structural steels having low nitrogen and low sulfur, and high carbon alloy tool-steels whose carbon, oxygen and/or sulfur content is strictly limited. In re-refining, any one of CaO and CaF 2 , CaO and Al 2 O 3 , and CaO, CaF 2 and Al 2 O 3 is used. For example, an Fe-Ni system alloy having 0.01% carbon and sulfur 0.005% can be produced. |