Method for hot-rolling a slab and hot-rolling mill

Abstract

The invention relates to a method for hot-rolling a slab ( 1 ), especially a steel slab, the slab ( 1 ) being subjected to at least two shaping steps at different temperatures in a hot-rolling mill ( 2 ), the slab ( 1 ) being cooled between two such shaping steps. In order to prevent ferrite from forming too soon during the hot-rolling, the slab ( 1 ) is cooled such that the lateral end sections ( 3, 4 ) of the slab ( 1 ) are cooled with a lower cooling efficiency than a center section ( 5 ) of the slab ( 1 ). The invention further relates to a hot-rolling mill ( 2 ) for hot-rolling a slab.

1 . A method for hot rolling a slab ( 1 ), especially a steel slab, wherein the slab ( 1 ) is subjected to at least two deformations at different temperatures in a hot rolling mill ( 2 ), wherein the slab ( 1 ) is actively cooled between two such deformations, and wherein the cooling of the slab ( 1 ) is carried out in such a way that the lateral regions ( 3 ,  4 ) of the slab ( 1 ) are cooled with lower cooling efficiency than the center region ( 5 ) of the slab ( 1 ), wherein the cooling operation is controlled by means of an integrated temperature computing unit in such a way that the temperature can be prevented from falling below the ferrite precipitation temperature, so that undesired ferrite formation is prevented, such that two slide plates ( 10 ′,  11 ′) that shield the nozzles of a cooling spray bar ( 12 ) are moved in a horizontal direction transversely to the rolling direction (W) in such a way that a well-defined delivery width of the stream of cooling medium from the cooling spray bar ( 12 ) is obtained. 
     
     
         2 . A method in accordance with  claim 1 , wherein the slab ( 1 ) is cooled by applying a cooling medium ( 6 ), such that the lateral regions ( 3 ,  4 ) of the slab ( 1 ) are at least partly shielded from the cooling medium ( 6 ). 
     
     
         3 . A method in accordance with  claim 1 , wherein the slab ( 1 ) is cooled in an intermediate cooling stand ( 7 ). 
     
     
         4 . A method in accordance with  claim 1 , wherein the slab ( 1 ) is cooled on a cooling line. 
     
     
         5 . A method in accordance with  claim 1 , wherein the hot rolling of the slab ( 1 ) is a multiphase rolling process, especially a thermomechanical rolling process. 
     
     
         6 . A hot rolling mill ( 2 ) for hot rolling a slab ( 1 ), especially a steel slab, such that the hot rolling mill ( 2 ) has at least two hot rolling stands ( 8 ,  9 ), such that at least one cooling station ( 7 ) in which the slab ( 1 ) can be cooled is arranged between the hot rolling stands ( 8 ,  9 ) or upstream of the roughing stand, such that the cooling station ( 7 ) has means ( 10 ,  11 ;  10 ′,  11 ′,  12 ) by which the amount of cooling capacity applied to the slab ( 1 ) can be varied along the width of the slab ( 1 ) in such a way that the lateral regions ( 3 ,  4 ) of the slab ( 1 ) are cooled with lower cooling efficiency than the center region ( 5 ) of the slab ( 1 ), and such that the means ( 10 ′,  11 ′,  12 ) consist of a cooling spray bar ( 12 ) for applying cooling medium ( 6 ) to the slab ( 1 ), wherein the width of the stream of cooling medium ( 6 ) can be adjusted ( 10 ′,  11 ′) over the width of the slab ( 1 ) by virtue of the fact that two slide plates ( 10 ′,  11 ′) that shield the nozzles of the cooling spray bar ( 12 ) are arranged in such a way that they can be moved in a horizontal direction transversely to the rolling direction (W), so that a well-defined delivery width of the stream of cooling medium from the cooling spray bar ( 12 ) is obtained. 
     
     
         7 . A hot rolling mill ( 2 ) in accordance with  claim 6 , wherein the cooling station ( 7 ) is an intermediate cooling stand. 
     
     
         8 . A hot rolling mill ( 2 ) in accordance with  claim 6 , wherein the cooling station ( 7 ) is a cooling line. 
     
     
         9 . A hot rolling mill ( 2 ) in accordance with  claim 6 , wherein the proper cooling width is obtained by adjusting it by electrical or mechanical means.