Effect of Forced Cooling Contraction on Shrinkage Cavity and Segregation of Ultra-thick Continuous Casting Slab

Abstract

Due to the shrinkage cavities and macro segregation that frequently happened in ultra-thick slab and affected the slab quality, a new technique called forced cooling contraction, which added extra cooling water in solidification end has been provided. The slice moving boundary model was established, the secondary cooling zone was divided into rolling zone, continuous bending zone and segment arc zone. The accuracy of secondary cooling calculation model was verified. The influence on shrinkage cavities and macro segregation was researched when the water flow was from 1,5; 2,5; 4 and 7 times of original water flow. Compared with original water flow, when time of water flow in segment arc zone is lower than 2,5, the shrinkage cavities length decreases. When water flow is 2,5 times of original water flow, the segregation degree and ratio decreased from 1,325 and 0,963 to 1,294 and 0,930, respectively. Combine with the results of shrinkage cavities and macro segregation. The considerable strength of forced cooling is 2,5 times of original water flow.

Keywords

• forced cooling contraction
• macro segregation
• shrinkage cavities
• ultra-thick slab