Continuous casting is a procedure for manufacturing semi-finished material, e.g. Blocks, ingots or slabs from metals and their alloys.
Contrary to the ingot pouring the procedure is continuously accomplished. But a soilless cooled mold is used, into which the liquid metal is poured. Within the mold solidifies the extrusion layer, which is then taken off in casting direction and which encloses liquid core. After leaving the mold the extrusion layer is continued to cool with water, until the strand solidified completely. According to the mold arrangement between horizontal and vertical continuous casting one differentiates. Those world-wide first continuous casting installation for steel went 1961 with the Dillinger hut into enterprise. Those world-wide first club continuous casting installation with mechanical strand reduction (Softreduction) went 2004 at the Saarstahl AG into enterprise.
A continuous casting installation consists of
The melt is usually transported with a pan in such a way specified by the fusion aggregate over the casting crane to the continuous casting installation and used in the ladle turntable. Over a soil drain, which is locked by a plug or a slidegate valve, the melt flows into the distributor. So that the liquid steel does not react with the atmospheric oxygen, the liquid steel in a shade pipe is led. The melt is taken off in the distributor by a cinder layer.
From the distributor the melt runs freely or by an immersion tube (also pouring tube called) into the mold. The flow is steered as a function of the casting level in the mold with a plug. The casting level in the mold is covered with cinder. This prevents re-oxidation of the melt, binds ascended impurities and serves as lubricant between the rigid bowl and the mold. For forming the cinder continuously flux powder is applied on the casting level. During pouring the mold is reciprocating moved, in order to prevent a caking on of the steel at the cooled walls of the mold and support the transportation procedure.
For casting on a dummy bar (dummy bar) is inserted from downside into the mold, for which the lower surface locks. The filled in steel rigidly on the dummy bar and is taken off downward with this. According to reaching the metallurgical length, the distance, which the strand needs, in order to solidify completely, the dummy bar and the casting strand are thus separated from each other.
The mold can be implemented either straight or curved. In straight molds the strand leaves the mold perpendicularly downward. In order too received a sufficient strand length for complete solidifying of the melt, the strand with a bending and an arranging unit must be bent into the horizontal. In curved molds the strand is already circle arc-shaped, which must be arranged after reaching the horizontal. Both concepts have their specific pro and cons, which result from the fact that on the one hand from bending the strand tears result and on the other hand a long vertical liquid distance for the purity of the steel offers advantages, since impurities can ascend into the cinder. Rinsed for improving the purity will with argon and it can the melt be electromagnetically agitated.
Underneath the mold the strand is cooled from the outside by air/water spraying. In addition it is supported by roles, in order to reduce a bulging, because of ferrostatic pressure the affecting the extrusion layer taken place.
After the Durcherstarren the strand on the run-out roller table with burners in lengths is cut, in order to receive the semi-finished material.
The continuous casting differentiates between meanwhile several procedures, which are dependent on the format of the strand which can be poured. Apart from the slab continuous casting for rectangular strands with large width up to 1600 mm and small thickness up to 400 mm for sheet metal production gives to be poured it also still the club and blooming rank casting, with which round, approximately square or even cross sections for the production of bars, wires and profiles. With the slab continuous casting one generally differentiates the slab continuous casting (thickness over 100 mm up to 400 mm), the roughed slab casting (thickness from 40 to 100 mm) and the thin slab casting (thickness 3 to 50 mm). With the two latter procedures substantial savings are possible in the range of the equipment technology and the energy balance. Further reduction of the transforming processes is reached by the thin volume pouring (thickness under 3 mm).
A slab with approximately 50 mm of thickness is produced by the Vorbandgiessen, which can be punctured directly in the finishing train of a hot rolling mill. Between the casting machine and the rolling aggregate a balance furnace is only needed. With this procedure economically simple can be manufactured. The disadvantage is its small flexibility and the tendentious worse surface quality.
By thin volume pouring who that metal bands manufactured, which do not have to be transformed, or only in few passes warmly. 2 spread today role thin volume pouring became original by Henry Bessemer in 19. Century patents. It could not transfer it however into the ready for the market one. Since center of the nineties this procedure for stainless steel and electric furnace steels is industrially used. Here the steel between two water-cooled rollers turning against each other solidifies and completely rigidly as volume, up to 1.5 mm of thickness, downward exhausts itself. In the plant typically a roll stand is arranged, in which after a Walzstich a minimum volume thickness can be achieved by 1 mm.
This procedure has the advantages the fact that only small capital outlays are necessary, are economically producible relatively small quantities and are saved by the omission of the for hot-rolling the energy for the reheating of the slabs and thus with small costs can be produced.
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