Method of continuously casting thin strip

Abstract

A method of continuously casting steel including steps of forming a casting pool of molten steel comprising a carbon content of less than 0.5% by weight on casting surfaces of a pair of internally cooled casting rolls having a nip formed between them, counter rotating the casting surfaces of the casting rolls toward each other to produce a cast steel strip moving downwardly away from the nip between the casting rolls, guiding the cast strip through a first enclosure adjacent the casting rolls as the strip moves away from the casting rolls, the first enclosure having a reducing atmosphere containing carbon monoxide and optionally hydrogen of at least 0.1%, establishing the reducing atmosphere in the first enclosure to control ingress of atmospheric air so as to maintain said atmosphere with a CO to CO₂ ratio of at least 1.5 during steady state operation.

Description

BACKGROUND AND SUMMARY[0001]This invention relates to the casting of metal strip by continuous casting in a twin roll caster.[0002]In a twin roll caster molten metal is introduced between a pair of counter-rotated horizontal casting rolls that are cooled so that metal shells solidify on the moving roll surfaces and are brought together at a nip between them to produce a solidified strip product delivered downwardly from the nip between the rolls. The term “nip” is used herein to refer to the general region at which the rolls are closest together. The molten metal may be poured from a ladle into a smaller vessel or series of smaller vessels from which it flows through a metal delivery nozzle located above the nip, so forming a casting pool of molten metal supported on the casting surfaces of the rolls immediately above the nip and extending along the length of the nip. This casting pool is usually confined between side plates or dams held in sliding engagement with end surfaces of th...

AI Technical Summary

Benefits of technology

[0026](d) moving the cast strip through pinch rolls and thereafter through a second enclosure upstream of a roll mill where the cast strip reduction is at least 10%, the atmosphere in the second enclosure being a controlled atmosphere containing a total of oxygen, water vapor and hydrogen of greater than 8% by

Problems solved by technology

When casting steel strip in a twin roll caster, the strip leaves the nip at very high temperatures of the order of 1400° C. and can suffer very rapid scaling due to oxidation at such high temperatures in an air atmosphere.

Such scaling may result in a significant loss of steel product.

Moreover, such scaling results in the nee

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