TSESHL technology is designed to meet the consumer's needs for piece, small-scale, as well as orders for non-standard products, at prices several times lower than prices for similar forgings, and in some cases is the only method, since manufacturing by forging may be economically inexpedient.
With the help of the TsESHL technology, it is possible to obtain rather simply and economically cast billets of a relatively complex configuration, the properties of which meet the requirements for the corresponding forgings. Smelting of metal at TsEShL is carried out in a crucible, completely lined with refractory materials, capable of working in a pair with slag for a sufficiently long time at temperatures characteristic of the electroslag process. At the same time, all technological aspects of the canonical ESR are implemented regardless of the options for its execution.
The resulting blanks differ from the blanks obtained by traditional casting in sandy-clay molds, and have a high level of quality, are subjected to comprehensive destructive and non-destructive testing.
The discovery of the new technology was due to an event that happened 55 years ago during the installation of a blast furnace at the Zaporizhstal plant, which was destroyed during the war. The installation was attended by engineers and scientists of the Institute of Electric Welding. Paton (IES). When welding vertical seams, automatic submerged arc welding was used. Once during welding, the arc suddenly stopped burning, but the welding process did not stop and the devices continued to show that there was current in the welding circuit! To everyone's surprise, the melting process continued! Electric current, passing through the liquid flux-slag, heated it to a temperature sufficient to melt the metal. This observation enabled scientists to discover the arcless electroslag welding process (ESW).
The study of the metal obtained as a result of such welding showed its excellent properties in terms of strength, ductility, purity and density of micro and macrostructure, chemical and physical homogeneity. This circumstance prompted scientists to think: what if we separate the metal from the weld and carry out not welding, but electroslag remelting (ESR). The first experiments carried out in 1952 proved the consistency of this assumption. An experimental setup was made. It consisted of a crystallizing vessel shaped like the required workpiece. The metal in the form of an electrode was immersed in a liquid conductive slag and a voltage was applied. As the current passed through the slag, heat was released, which melted the electrode, the metal passed through the slag drop by drop, was cleaned of impurities and filled the crystallizer. As a result of the experiment, a high quality metal sample was obtained.
And already in 1958, the world's first ESR unit was put into operation at the Dneprospetsstal electrometallurgical plant in Zaporozhye. Its advantages were so convincing that within a short period of 4–5 years almost all domestic metallurgical plants had electroslag furnaces in their arsenal. The invention was patented in many countries of the world, including France, USA, Japan, Sweden. In total, the institute received more than 600 patents in this area and the USSR is rightfully considered the ancestor of this technology.
The method for the production of castings with a central internal cavity by the CESHL method was proposed by the Institute of Electric Welding named after V.I. E.O. Paton (copyright certificate 599426 dated 30.12.82 by B.E. Paton, B.I.Medovar, V.L.Shevtsov, etc.)
In CESHL, the metal melted by the electroslag method in a separate melting tank is poured together with the slag into a rotating casting mold.
At the same time, being the first to enter the rotating mold, the liquid slag previously used for remelting is distributed around the periphery of the casting mold and forms a thin slag skull on its walls, which excludes welding of the casting to the mold. The rest of the slag forms a liquid layer rotating at the speed of the mold.
A thin and uniform layer of slag skull is obtained due to the high degree of overheating of the slag by 200 ... 400 ° C above the temperature of the metal melt, which is characteristic of the electroslag smelting process and is unattainable and unacceptable in ordinary foundry.
Liquid metal, following the slag, and partly with it, into a rotating mold under the action of centrifugal forces, passes through a layer of liquid slag, displaces it to the axis of rotation and fills the space at the walls of the mold.
A characteristic feature of this casting method, which is impossible under the conditions of a conventional ESL, is the additional intensive refining of the metal as it passes through the slag under the action of centrifugal forces in a rotating mold.
Due to the large difference in specific gravity of liquid metal and slag, complete separation occurs during rotation, eliminating entanglement of slag in the metal. This is also facilitated by the direction