Study On Heat-transfer Model Of Solidification And Prediction Model Of Soft-reduction Position For Continuous Casting Slab

Along with the enhanced request for the steel products quality, it becomes a important topic to improve the steel quality. Center segregation and center porosity have a bad influence on the product quality. Soft reduction technology can effectively improve the central segregation in continuous casting slab, its main technical parameters are: reduction position,reduction amount and reduction ratio. This paper focuses on how to find out the reduction position for different conditions. Based on the investigation of NO.3 caster in a steel plant, a two-dimensional transient heat transfer model for simulate solidification process had been established. The finite difference method was used to solve it, and"surface temperature measurement"method was employed to validate the accuracy of heat transfer model. According to the simulated results of validated model, the affects of casting speed,superheat and slab thickness on the temperature field were analyzed. At the same time the solidification heat transfer model was applied to build a secondary cooling control and soft reduction position prediction model, the affects of casting speed,superheat on soft reduction position had also been analyzed. And a application with friendly interface was programmed in Java.The simulated results showed that casting speed had a great effect on surface temperature,center temperature. In case of other parameters kept in constant, the isotherm of slab moved to the surface quickly as the casting speed increased, and this made the surface temperature raised. the casting speed increased 0.1m/min,the surface temperature raised 15℃;Superheat had a little effect on surface temperature,center temperature. As superheat increased 5℃the surface temperature, center temperature increased approximately 4℃, and the influence became even less at the end of secondary cooling zone; Slab thickness also have a effect on center temperature and surface temperature, the effect on surface temperature is mainly located at radiation zone and the effect on center temperature become remarkable from the end of secondary cooling zone.The analyses on the contributing factors of reduction position indicated that, casting speed was the major contributing factor of reduction position, the casting speed increased 0.1m/min, the liquid pool length extended 1.8m along the casting direction, and the width of the reduction zone also increased with the casting speed. Superheat had a little effect on reduction position, as the superheat increased, reduction position moved slowly along the casting direction, and the width of reduction zone decreased slowly.