Tundish Stopper is a refractory container used in continuous casting of steel making. It first receives molten steel poured from ladle and then distributes it to crystallizer by the tundish nozzle.
1. The function of China tundish stopper
(1) Reduce the static pressure of molten steel, maintain the stable liquid level of molten steel in China tundish stopper, and steadily inject molten steel into crystallizer;
(2) promote the inclusion in the molten steel to float further to purify the molten steel;
(3) split molten steel. For multi-flow continuous casting machine, molten steel is distributed to each mold through China tundish stopper.
(4) storage of molten steel. When the ladle is replaced by multi-furnace continuous pouring, the drawing speed is not reduced to create conditions for multi-furnace continuous pouring. It can be seen that the main function of tunic is decompression, steady flow, removal of inclusions, storage and diversion of molten steel.
2.Metallurgical function of China tundish stopper
(1) Purification function
In order to produce high purity steel, using retaining wall dam, argon blowing, ceramic filter and other measures in tundish can greatly reduce the content of non-metallic inclusions in steel.
(2) temperature regulation function
In order to make the temperature change of molten steel less than 5℃ before, during and after the China tundish stopper in the pouring process, close to the liquidus temperature, expand the equiaxed crystal zone of the billet and reduce the center segregation, measures such as adding small pieces of scrap steel to the tundish and blowing iron powder can be taken to adjust the temperature of molten steel.
(3) composition fine-tuning
By feeding aluminum, titanium, boron and other core-wires into the mold through the center hole of the China tundish stopper plug rod, the fine-tuning of the microalloy composition in the steel is realized, which not only improves the recovery rate of easily oxidized elements, but also avoids the blockage of the water outlet.
(4) Refining function
To absorb the inclusions floating in the steel, a double layer slag was added to the water surface of the intermediate cladding steel, or a calcium wire was fed to change the Al2O3 inclusions to prevent the spout from blocking.
Heating function
Induction heating and plasma heating are adopted in tundish to accurately control the pouring temperature of molten steel. The longer the molten steel stays in the tundish, the more time the inclusions have to rise and the cleaner the molten steel will be. In order to increase the residence time of molten steel, the China tundish stopper with large capacity and deep melting pool is an effective way.
3. Refractory materials for intermediate packing
The molten steel temperature in the tundish is about 1470 ~ 1560℃, because the tundish needs to leave a certain thickness of residual steel after casting, while the stopper rod and residual steel are frozen in the China tundish stopper when the tundish is down the line, and the tundish down the line is removed together with the working liner after cooling, and the working liner is scrapped after one-time service, so the requirements on the working liner of the tundish are not as high as those of the ladle.
(1) Permanent lining casting material
The permanent lining of China tundish stopper is usually made of aluminum-silicon castable, which should have good strength, volume stability and thermal shock resistance according to the service conditions of tundish. Corina produces tundish castables with a service cycle life of about 700 ~ 800 furnaces.
(2) Work lining dry material
China tundish stopper alkaline dry material is composed of sintered magnesia, magnesia calcium sand or fused magnesia, magnesia calcium sand and medium high temperature sintering agent, a small number of low temperature binder. Magnesium dry lining has the advantages of simple construction, high baking thermal efficiency, easy separation of steel slag from permanent lining, quick turnover of tundish, improved quality of molten steel, long service life and so on.
