IMPROVEMENTS IN OR RELATING TO PROCESSES OF AND FURNACES FOR CONSUMABLE-ELECTRODE-FORMING CAST METAL INGOTS

摘要

1,240,550. Casting processes. ALLEGHENY LUDLUM STEEL CORP. 4 Dec., 1968 [29 Dec., 1967], No. 57691/68. Headings B3F. [Also in Divisions H3-H5] In a consumable electrode arc furnace the consumable electrode 30 is made positive relative to the molten pool 28 and a metal oxide is added to the pool so that more heat is dissipated in the electrode tip 2 than in the molten pool. The metal oxide is selected from barium oxide, calcium oxide, nickel oxide, strontium oxide, thorium oxide, titanium oxide, cerium oxide or caesium oxide. The oxide may be added to the molten pool in granular form during the initial stage of operation, during hot-topping, or may be added continuously. Preferably a tube or tubes 64 of the same metal e.g. steel, as the electrode 30 and containing compacted oxide may be secured to the electrode so that oxide is continuously added to the molten pool as the electrode tip and tube or tubes 64 melt. The electrode 30 is raised and lowered by a motor 44 controlled by a conventional arc voltage control system 48. By providing oxide packed steel tubes 64 at the top of electrode 30 and making electrode 30 negative, the voltage is reduced when the oxide is released, the arc is stabilized and ideal hot topping conditions are achieved. The chamber 18 may be evacuated or filled with argon which has the effect of pinching the arc away from the crucible wall 12.