| 摘要 |
1,172,227. Casting processes. ALLEGHENY LUDLUM STEEL CORP. 19 Oct., 1966 [20 Oct., 1965], No. 46864/66. Heading B3F. [Also in Divisions C7 and H5] To form a pure ingot 18, an arc is struck between at least one electrode 24 and a starter body (of the electrode material) in a cooled mould 10, e.g. of copper, to form a pool of molten metal and then adding slag ingredients (which may have been prefused together, cooled and subdivided) to form a layer 22 of molten slag to extinguish the arc and melt the electrode end which is maintained in contact with the slag while A.C. is passed between the electrode end and the molten metal 20 or between the ends of adjacent electrodes. The electrode or electrodes is or are lowered, possibly automatically, at the rate at which the length is reduced by the melting. As shown there are three consumable electrodes 24, each connected to a phase of a three-phase A.C. supply and each with a driving ram 26. A starter plate is first placed on the mould bottom and covered with scraps of the metal. It may then be partly covered with prefused slag. The electrodes are lowered to strike an arc, e.g. in a helium atmosphere, and establish a pool of molten metal before slag is slowly introduced until it extinguishes the arc and electroslag melting proceeds. Melting of steel may be performed in a vacuum. A helium purge may be maintained, particularly for melting Ti or Zr, while cooling the ingot 18. The slag (see Division C7) may comprise CaF 2 alone or mixed with Al 2 O 3 and CaO and (possibly) TiO 2 . A mixture of Al 2 O 3 , MgO, CaO and SiO 2 may be used.
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