Method for improving internal quality of casting blank by composite intervention

Abstract

Provided is a method for improving internal quality of casting blank by composite intervention. The method comprises following steps: 1), machining pure iron or steel with the approximate content of steel grades to be an easily-melted cold bodies moving with molten steel and then drying; 2), baking feeding guide pipes which are made by refractory material and immersing them into a crystallizer below the molten steel surface; aligning feeding guide pipe openings to the center of steel streams as for round and square billets; utilizing two guide pipes for plate blank and distributing them on two sides of a wide surface of the crystallizer; 3), continuously injecting the dried cold bodies into a high-temperature region of a molten pool of the crystallizer, adding the cold bodies in the amount of 0.8-1.3% of casting blank; adopting the crystallizer to electromagnetically stir during the continuous casting process. The method for improving internal quality of casting blank by composite intervention has following beneficial effects: cold bodies are fed into the crystallizer such that superheat and temperature gradient of molten steel during mass production of continuous casting; the solidification structure of casting blank is improved; quality flaws of the internal quality of the casting blank is reduced; the temperature field of the crystallizer is improved; and therefore the purposes of increasing equiaxial crystal ratio and improving internal quality of the casting blank are fulfilled.

Description

technical field [0001] The invention relates to the technical field of continuous steel casting, in particular to a method for improving the internal quality of a cast slab through composite intervention. Background technique [0002] The solidification process of molten steel plays an important role in the quality of steel. In continuous casting production, molten steel solidifies from outside to inside in the crystallizer, forming a large temperature gradient field from inside to outside on the section of solidified slab. Due to non-equilibrium crystallization and volume shrinkage, internal defects such as element segregation and central porosity are formed in the central area of ​​the slab. As the size of the slab increases, the center porosity, shrinkage cavity and segregation become more serious. [0003] To improve the internal quality of the slab is to improve the solidification structure of the slab, reduce segregation, and increase the density of the center. At p...

AI Technical Summary

Problems solved by technology

But when such a large amount of cold steel is added, it cannot be completely melted in the vertical section of the continuous casting machine. Due to gravity, the cold steel that is not fully melted deviates from the thickness center of the slab in the bending section, so the solidification end point deviates from the thickness center of the slab. Cause composition segregation, and even produce abnormal steel defects in severe cases

Moreover, due to the addition of cold steel, the temperature of the molten steel decreases, the fluidity of the molten steel becomes poor, and the inclusions in the molten steel are difficult to float up, resulting in internal inclusion defects.

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