ESR(Electro Slag Remelting) furnace is a special melting installation in which the consumable electrode immerged into molten slag pool is melted by the Joule heat produced when electric current flows through the molten slag, then the melted metal drops are purified and refined when they go through the molten slag and at last are crystallized into an ingot in the water-cooled crystallizer. Due to the impurity-removing function of molten slag and better crystallizing conditions, the ESR metal has good properties, such as high purity, fine and uniform structure, no white point and annual-ring segregation, ultra low sulphur content as well as small and diffusible impurity etc. Therefore, ESR is at an important position in the production of medium and large forgings and billets (including big steel pipe and roller etc.), Ni-based alloy, high quality tool and mold steel, maraging steel and castings of abnormal shapes. The output of electro-slag steel per year has reached several hundred thousands tons in China. The ESR furnaces has become necessary equipment for special steel plants.
The DZ series ESR furnaces with dual working positions and high efficiency developed by our company have following advantages:
1. The ESR furnace adopts pit type frame structure and has good rigid as a whole, to make it possible to control remelting speed reliably by the use of high accuracy electronic weight measuring system;
2. The furnace adopts single electrode, single phase, dual furnace positions and the integral disassembly of the mold consisting of crystallizer and bottom water box. In this case, when remelting is carried out in one furnace position, the preparation before remelting and the removing of ingot after remelting can be carried out in another furnace position at the same time, and then the efficiency is doubled.
3. The use of electronic weight measuring system with high accuracy may calculate quickly and then control the meting rate of consumable electrode to obtain optimal uniform crystallization. The high quality products can be obtained specially in remelting high alloy steel or electro-slag ingot of large diameter;
4. The heavy current line on the secondary side adopts parallel arrangement as well as reversal and close arrangement (coaxial conducting). The connection between electrode lifting mast and heavy current line is realized by electric brush units, to reduce the length of water-cooled cable, inductance and power consumption;
5. The melting rate and slag resistance are auto-controlled, to make remelting process stable. The melting rate may be set by menu to make process optimization easy and reliable;
6. The efficiently-sealed inert gas protection hood is equipped at the port of crystallizer to ensure high quality products.
The ESR furnace consists of three main parts: rotatable furnace head, fixed melting station and electrical system.