Method of continuously casting thin strip

A method of continuously casting steel comprising:

• (a) forming a casting pool of silicon killed molten steel on casting surfaces of a pair of internally cooled casting rolls having a nip formed between them,
• (b) counter rotating the casting surfaces of the casting rolls toward each other to produce a cast steel strip moving downwardly away from the nip of the casting rolls such that iron silicate is formed on the surface of the cast strip,
• (c) 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 of at least 0.1% and optionally hydrogen of at least 0.1%, and
• (d) establishing said reducing atmosphere in the first enclosure during steady state operation to control ingress of atmospheric air so as to maintain said atmosphere with a CO to CO2 ratio of at least 1.5.

A method of continuously casting steel comprising:

• (a) forming a casting pool of molten steel comprising iron and silicon on casting surfaces of a pair of internally cooled casting rolls having a nip formed between them,
• (b) 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 such that iron silicate is formed on the casted surface of the cast strip,
• (c) 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 of at least 0.1% and optionally hydrogen of at least 0.1% to control ingress of atmospheric air so the atmosphere in the first enclosure has a CO to CO2 ratio of at least 1.5 during steady state operation,
• (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 volume during steady state operation.