Steel continuous casting method

Abstract

Provided is a steel continuous casting method capable of improving the quality of a cast piece cast in the period after the casting completion. A steel continuous casting method of performing continuous casting while a cast piece (3) is subjected to rolling reduction includes subjecting a cast piece (3) being continuously cast to rolling reduction and, after the casting completion, changing a rolling reduction gradient in a segment (14) of applying the rolling reduction, to control a rolling reduction speed within a predetermined range.

1 . A steel continuous casting method of performing continuous casting while a cast piece is subjected to rolling reduction, the method comprising:
 subjecting the cast piece being continuously cast to rolling reduction; and   after casting completion, changing a rolling reduction gradient in a segment of applying the rolling reduction, to control a rolling reduction speed within a predetermined range.   
     
     
         2 . The steel continuous casting method according to  claim 1 , the method comprising:
 after the casting completion, a deceleration step of decreasing a casting speed of the cast piece from a first casting speed that is a casting speed before the casting completion to a second casting speed that is a casting speed for head solidification of the cast piece;   after the deceleration step, a head solidification step of maintaining the casting speed of the cast piece at the second casting speed for a time period for the head solidification; and   after the head solidification step, an acceleration step of increasing the casting speed of the cast piece from the second casting speed to a third casting speed that is a casting speed of redrawing the cast piece.   
     
     
         3 . The steel continuous casting method according to  claim 2 , wherein
 the rolling reduction gradient is controlled to satisfy Expression (4) in the deceleration step,   the rolling reduction gradient is controlled to satisfy Expression (5) in the head solidification step, and   the rolling reduction gradient is controlled to satisfy Expression (6) in the acceleration step:   
       
         
           
             
               
                 
                   
                     0.5 
                     < 
                     
                       V 
                       × 
                       Z 
                     
                     < 
                     3. 
                   
                 
                 
                   
                     ( 
                     4 
                     ) 
                   
                 
               
             
           
         
         
           
             
               
                 
                   
                     0.5 
                     < 
                     
                       V 
                       × 
                       Z 
                     
                     < 
                     1.5 
                   
                 
                 
                   
                     ( 
                     5 
                     ) 
                   
                 
               
             
           
         
         
           
             
               
                 
                   
                     0.5 
                     < 
                     
                       V 
                       × 
                       Z 
                     
                     < 
                     3. 
                   
                 
                 
                   
                     
                       ( 
                       6 
                       ) 
                     
                   
                 
               
             
           
         
         where V is a casting speed (m/min), and Z is a rolling reduction gradient (mm/m).