In terms of heating principle, electroslag remelting furnace is a resistance melting furnace. Electroslag remelting process is that the lower end of the electrode is immersed in molten slag. When AC current passes through the high resistance slag pool, it produces a lot of heat. It melts the end of the electrode embedded in the molten slag. The molten metal droplets produced by melting pass through the slag pool and drip into the metal molten pool. Then they are cooled by the water-cooled crystallizer and condensed into ingots. In this process, the metal droplets are in full contact with the slag with high temperature and high alkalinity, resulting in strong metallurgical chemical reaction, which makes the metal refined.
The key technology of electroslag remelting furnace is slag system. In electroslag remelting furnace, the main functions of slag are four points: heat source, protection, molding and metallurgical chemistry. The characteristics of slag are:
(1) It has high resistivity and can generate enough heat in the smelting process to ensure metal melting, heating and purification.
(2) It has certain alkalinity, so it has good deoxidation and desulfurization effect.
(3) It does not contain stable oxides, such as MnO, FeO, etc.
(4) It has good fluidity to ensure full convective heat exchange and liquid physical and chemical reaction at high temperature.
(5) It has a low melting point, generally 150-250 ℃ lower than the melting point of the molten metal, which makes the spindle form well.
(6) It has a high boiling point so that it will not volatilize a lot at high temperature.