Types of steel breakout during continuous casting process.The more serious problem in continuous casting is steel breakout. When the shell of the cast stream r
Types of steel breakout during continuous casting process.
The more serious problem in continuous casting is steel breakout. When the shell of the cast stream ruptures, the static molten steel in the shell overflows and blocks the machine, which requires a lot of manpower. Generally, it will be divided into different situations according to the appearance of the broken steel billet shell, and different measures will be taken accordingly.
1. Suspension or bonding causes leakage, that is, the molten steel is bonded to the copper mould tube, so it is called bonding or suspension. This may be caused by unsuitable lubrication or improper adjustment between the crystal parts and the blank shell. The discomfort of lubrication may be caused by poor quality mold powder, slag inclusion in the billet shell, molten steel overflow, corner joints, poor lubrication and unevenness of the billet continuous casting machine.
2. Cracks cause breakout, that is, longitudinal cracks at the corners of the billet shell and longitudinal cracks on the wide surface will cause breakout. If longitudinal cracks cause steel breakout, it may be due to uneven flow of mold powder, and uneven heat transfer causes uneven thickness of the blank shell. Improper selection of mold powder and uneven cooling caused the blank shell to crack during cooling.
3. Breakout with slag inclusions-the slab shell entrains protective slag or large-grain inclusions to reduce heat transfer, forming a thin slab shell and breakout. During billet continuous casting, secondary oxidation products, improper deoxidation products in high-viscosity slag during low-carbon steel smelting, and improper spraying of medium aluminum wire cause high Al2O3.
In order to prevent leakage, we need to understand the fluidity of molten steel, the temperature state of molten steel, the baking state of the tundish and the nozzle, and the quality of the protective slag. The size of the injection flow and the residence time of molten steel in the crystal parts should be determined according to the section of the cast slab.
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