Process and device for producig a high-strength steel strip

Abstract

Process for producing a high-strength steel strip, in which liquid steel is cast in at least one continuous-casting machine with one or more strands to form a slab and, utilizing the casting heat, is conveyed through a furnace device, undergoes preliminary rolling in a preliminary rolling device and, in a final rolling device, is finishing-rolled to form a steel strip with the desired final thickness, and, in a continuous, endless or semi-endless process, the slab undergoes preliminary rolling in, essentially, the austenitic range in the preliminary device and, in the final rolling device, is rolled in the austenitic range or, in at least one stand of the final rolling device, is rolled in the two-phase austenitic-ferritic range, the austenitic or austenitic, ferritic rolled strip, after leaving the final rolling device, is cooled rapidly in order to obtain the desired structure.

1 - 4 . (Cancelled)  
     
     
         5 . A device for producing a steel strip, comprising 
 at least one continuous-casting machine for casting thin slabs,    a furnace device for homogenizing the slabs,    a preliminary rolling device, downstream of the furnace device, for rolling the slabs in essentially the austenitic range and subjecting the slabs to preliminary size reduction,    a final rolling device for rolling the slab down to a strip with the desired final thickness in the austenitic range or, in at least one stand of the final rolling device, in a two-phase austenitic-ferritic range,    a coiler device for coiling the strip,    a cooling device, to cool the strip immediately after leaving the final rolling device, with a cooling capacity of at least 2 MW/m 2  placed between the final rolling mill stand of the final rolling device and the coiler device, immediately after the final rolling device; and    a shearing device between the cooling device and the coiler for cutting the slabs.    
     
     
         6 . The device according to  claim 5 , wherein said final rolling is performed at a temperature at which a desired amount of ferrite is present, and the rapid cooling of the strip leaving the final rolling device is to a temperature below Ms (start martensite), within the temperature range in which martensite is formed.  
     
     
         7 . The device according to  claim 5 , wherein said final rolling is performed a temperature at which a desired amount of ferrite is present, and the rapid cooling of the strip leaving the final rolling device ( 14 ) is cooling to a temperature above Ms (start martensite), and at a cooling rate at which bainite is formed.  
     
     
         8 . The device according to  claim 5 , wherein said preliminary rolling comprises lubricating rolling the slab, on at least one said stand of the preliminary rolling device ( 10 ).  
     
     
         9 . The device according to  claim 5 , wherein said preliminary rolling comprises lubricating rolling the slab on every stand of the preliminary rolling device ( 10 ).  
     
     
         10 . The device according to  claim 5 , wherein said final rolling comprises lubricating rolling the preliminarily rolled product on at least one said stand of the final rolling device ( 14 ).  
     
     
         11 . The device according to  claim 5 , wherein said preliminary rolling comprises lubricating rolling the slab on at least one said stand of the preliminary rolling device ( 10 ) and said final rolling comprises lubricating rolling the preliminarily rolled product on at least one said stand of the final rolling device ( 14 ).  
     
     
         12 . The device according to  claim 5 , wherein said final rolling comprises lubricating rolling, on every said stand of the final rolling device ( 14 ).  
     
     
         13 . The device according to  claim 5 , wherein said preliminary rolling comprises lubricating rolling the slab, on every said stand of the preliminary rolling device ( 10 ) and final rolling comprises lubricating rolling the preliminarily rolled product, on every said stand of the final rolling device ( 14 ).  
     
     
         14 . The device according to  claim 5 , wherein said casting produces a slab having a thickness of less than 100 mm.  
     
     
         15 . The device according to  claim 5 , wherein the shearing device is for cutting the strip to standard coil dimensions.  
     
     
         16 . The device according to  claim 5 , wherein said at least one continuous casting machine comprises a vacuum tundish.  
     
     
         17 . The device according to  claim 5 , wherein the rolling of the preliminarily rolled product in the final rolling device is in the austenitic range.  
     
     
         18 . The device according to  claim 5 , wherein the final rolling of the preliminary rolled product in the final rolling device is in the two-phase austenitic-ferritic range.