| 摘要 |
<p>A molten metal is refined in a vacuum or in a low oxygen partial-pressure atmosphere and then further refined (re-refined) by heating the metal by the inert gas plasma technique. The object metals are those of which the content of carbon, oxygen and/or sulfur is severely restricted, such as stainless steel, nickel-base alloy, iron-nickel alloy, steel for electromagnetic material, and intermediate-carbon structural steel and high-carbon alloy tool steel, both of which are reduced in the content of nitrogen and sulfur. The re-refining is conducted by using as the flux any of CaO/CaF2, CaO/Al2O3 and CaO/CaF2/Al2O3. The invention method provides, e.g., an iron-nickel alloy containing at most 0.01 % of carbon and at most 0.005 % of sulfur.</p> |
