As a hardware raw material, inclusions in the molten steel in the production process will seriously affect the performance of the steel and restrict the use of steel. Therefore, effective measures must be taken to remove inclusions in the steel and improve the performance of the steel. The removal methods of inclusions in molten steel mainly include molten steel argon blowing technology, crystallizer electromagnetic technology, and tundish filtration technology.
1. Argon blowing technology
Argon blowing is a mature technology in modern steelmaking applications. The principle is that a special device is used to uniformly inject the inert gas into the molten steel to form tiny bubbles. When the bubbles float, the intergranular particles are adsorbed on the surface by the interfacial tension, and are floated to the liquid surface for removal. In the argon blowing technology, a technology has been developed, namely a tundish air curtain retaining wall, which is embedded with a row of venting devices at the bottom of the bag, and a micro-bubble is blown into the molten steel to form a gas curtain retaining wall. When the inclusions collide with the bubbles, they are adsorbed on the surface of the bubbles and are suitable for removal of inclusions of 50-200 μm.
2, crystallizer electromagnetic technology
Crystallizer electromagnetic technology includes electromagnetic stirring and electromagnetic braking, which work similarly. Electromagnetic stirring is to provide a linear motion sensor behind the slab in the crystallizer to generate a moving magnetic field to drive the molten steel near the meniscus in the crystallizer to rotate in the horizontal direction to achieve the purpose of mixing. Suitable for inclusion removal of less than 20μm.
Electromagnetic braking is the addition of a pair of constant electromagnetic fields at the two broad faces of the crystallizer, so that the direction of the magnetic field passes perpendicularly through the two broad faces of the crystallizer. After the molten steel flows out from the side hole of the nozzle, it passes through the magnetic field at a high speed. Because the molten steel is electrically conductive, an induced current is generated. Under the action of the electromagnetic field, the molten steel is subjected to an electromagnetic force opposite to the direction of its own flow, which is a decrease in the flow velocity of the molten steel. The purpose of braking. The technology was first developed jointly by Sweden and Japan, and the metallurgical effect is good.
3, tundish filtering technology
The tundish filtering technology is to add a filter device on the basis of the retaining wall dam, mainly removing the inclusions by mechanical blocking and surface adsorption. The filter is made of a refractory material with a microporous structure that spans the two broad sides of the tundish, completely separating the tundish, and the molten steel can only pass through the micropores. This not only prolongs the residence time of the inclusions in the molten steel, but also ensures the residence time of the micro-inclusions in the molten steel, and ensures that the micro-inclusions have sufficient time to adsorb on the filter to achieve the purpose of removing inclusions. . Suitable for all inclusions larger than 20μm.
In the application, the existing technology is difficult to completely complete the task of completely removing the inclusions, so a combination of various technologies should be sought to find a more reasonable and feasible inclusion removal method and technical parameters to achieve "zero inclusions".
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Label: hardware raw material steel liquid removal method
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