GB1251660A - - Google Patents

Abstract

1,251,660. Casting processes. ELECTRICITY COUNCIL. 18 Nov., 1969 [17 Oct., 1967], No. 49351/68. Heading B3F. [Also in Division H5] Electroslag melting apparatus for producing metal ingots 18, e.g. of steel, comprises a cooled ingot-mould 10, 11, 12, containing molten slag 15, a hollow electrically conductive electrode assembly 13 loaded with pre-reduced metal powder 14, e.g. iron powder and alloying and non-metallic ingredients, and arranged at least partly immersed in the molten slag 15, and means for passing current between the electrode and the mould structure from a source (not shown). Two graphite electrodes 23, immersed in the molten slag 15, may be used to carry the greater part of the melting current. The top of the mould may be sealed by an air-tight head (not shown) and the internal atmosphere is introduced and controlled through a pipe (not shown). A low vacuum, or neutral or reducing conditions, may be established, using argon or carbon monoxide. The electrode tube 13 may be of mild steel which melts to form part of the ingot produced, and may be plugged at its lower end with sintered or compacted powder or steel of the required composition. Alternatively a hollow graphite electrode has metal powder continuously poured therethrough at a suitable speed to allow fusing as the powder passes through the molten slag. A.C. or D.C. may be used, and multiphase operation carried out, using rotating electrode arms with an oscillating mould for continuous casting. Ports 10, 11 of the mould are electrically insulated from one another by insulation 12 but are separable, as shown, by the base 10 being withdrawn downwards. A layer of solidified slag forms between the ingot and the mould walls.