Steel continuous casting method

Abstract

Provided is a steel continuous casting method that can identify the final solidification position accurately and inexpensively. A steel continuous casting method comprises: increasing a gap between the facing cast steel support rolls toward a downstream side in a casting direction of the cast steel, in a section; applying rolling reduction to the cast steel by a roll segment having a plurality of pairs of cast steel support rolls whose rolling reduction amounts are controlled by hydraulic cylinders, at least in a predetermined range; measuring a pressure difference between a plurality of hydraulic cylinders and estimating a final solidification position of the cast steel based on the pressure difference; and controlling a rolling reduction amount of the cast steel so as to satisfy predetermined formulas in a roll segment estimated to be the final solidification position and a roll segment immediately preceding the roll segment.

1 . A steel continuous casting method of casting cast steel withdrawn from a mold while supporting the cast steel by a plurality of pairs of cast steel support rolls, cast steel support rolls of each of the plurality of pairs facing each other with the cast steel therebetween, the steel continuous casting method comprising:
 increasing a gap between the facing cast steel support rolls toward a downstream side in a casting direction of the cast steel, in a section;   applying rolling reduction to the cast steel by a roll segment having a plurality of pairs of cast steel support rolls whose rolling reduction amounts are controlled by hydraulic cylinders, at least in a range from a position where a solid phase rate of a thickness central part of the cast steel is 0.2 to a position where the solid phase rate is a critical solid fraction of fluid flow in the casting direction;   measuring a pressure difference between a plurality of hydraulic cylinders and estimating a final solidification position of the cast steel based on the pressure difference; and   controlling a rolling reduction amount of the cast steel so as to satisfy the following formulas (1) and (2) in a roll segment estimated to be the final solidification position and a roll segment immediately preceding the roll segment:   
       
         
           
             
               
                 
                   
                     0.5 
                     < 
                     
                       V 
                       × 
                       Z 
                     
                     < 
                     3. 
                   
                 
                 
                   
                     ( 
                     1 
                     ) 
                   
                 
               
             
           
         
         
           
             
               
                 
                   
                     
                       0.5 
                       R 
                     
                     < 
                     Db 
                     < 
                     
                       2 
                       ⁢ 
                       R 
                     
                   
                 
                 
                   
                     ( 
                     2 
                     ) 
                   
                 
               
             
           
         
         where Vis a withdrawal speed of the cast steel in m/min, Z is a rolling reduction gradient in mm/m, Db is a bulging amount of the cast steel in mm, and R is a total rolling reduction amount of the cast steel in mm.