Abstract: Nail-shooting technique was applied in measurement of billet produced by Jiyuan Iron & Steel Company，then the thickness of solidified slab shell in secondary cooling region was measured. The liquid core length and the solidification coefficient of continuous cast billet were calculated by use of the solidification law. Reasonable casting speed and the radio of water for cooling effect of the caster were provide, and effects of casting speed, the radio of water, superheat of liquid steel on the solidification of the continuous casting billet were taken further research. According to the current end position of the electromagnetic stirring condition on Jiyuan No.2 caster, the reasonable installation position and optimization results of the specific process parameters were put forward. The result showed that the steel carbon segregation index was below 1.11 after improvement, which met the enterprise control requirements of the product quality.

Key words: nail-shooting technique, billet, solidification coefficient, electromagnetic stirring, carbon segregation index