System and method for producing steel products in the form of wires and/or bars

Abstract

A system for the thermomechanical rolling of long semi-finished steel products includes a first rolling unit; a second rolling unit, arranged downstream of the first rolling unit; a first thermomechanical sizing block, arranged downstream of the second rolling unit; a second cooling device, arranged between the second rolling unit and the first thermomechanical sizing block; a cooling-bed, ring-laying and/or coil-winding device, arranged downstream of the first thermomechanical sizing block; a third cooling device, arranged between the first thermomechanical sizing block and the cooling-bed, ring-laying and/or coil-winding device; and a structure-sensor device, which is arranged between the first thermomechanical sizing block and the cooling-bed, ring-laying and/or coil-winding device, and can be used for determining directly in the ongoing process a martensitic structure, in particular a proportion of martensite in percent by area, in the thermomechanically rolled long semi-finished steel product or in the steel product.

1 .- 11 . (canceled) 
     
     
         12 . A system ( 1 ) for thermomechanical rolling of long semi-finished steel products ( 2 ) into wire-shaped and/or rod-shaped steel ( 3 ), comprising:
 a first rolling unit ( 5 );   a second rolling unit ( 7 ), arranged downstream of the first rolling unit ( 5 );   a first thermomechanical sizing block ( 11 ), arranged downstream of the second rolling unit ( 7 );   a second cooling device ( 9 ), arranged between the second rolling unit ( 7 ) and the first thermomechanical sizing block ( 11 ,  11 . 1 );   a cooling-bed, ring-laying, and/or coil-winding device ( 16 ), arranged downstream of the first thermomechanical sizing block ( 11 );   a third cooling device ( 14 ), arranged between the first thermomechanical sizing block ( 11 ) and the cooling-bed, ring-laying, and/or coil-winding device ( 16 ); and   a structure-sensor device ( 17 ), arranged between the first thermomechanical sizing block ( 11 ) and the cooling-bed, ring-laying, and/or coil-winding device ( 16 ),
 wherein the structure-sensor device ( 17 ) is configured to directly determine a martensitic structure in the thermomechanically rolled long semi-finished steel product ( 2 ) or in the wire-shaped and/or rod-shaped steel ( 3 ) during an ongoing process. 
   
     
     
         13 . The system according to  claim 12 , further comprising:
 a first cooling device ( 6 ), arranged between the first rolling unit ( 5 ) and the second rolling unit ( 7 ),   wherein the structure-sensor device ( 17 ) is configured to determine a proportion of martensite in percent by area (A.-%).   
     
     
         14 . The system ( 1 ) according to  claim 12 ,
 wherein the structure-sensor device ( 17 ) is arranged
 directly upstream of the cooling-bed, ring-laying, and/or coil-winding device ( 16 ), 
 directly upstream of a separating device upstream of the cooling-bed, ring-laying, and/or coil-winding device ( 16 ), or 
 downstream of the third cooling device ( 14 ). 
   
     
     
         15 . The system ( 1 ) according to  claim 12 ,
 wherein the structure-sensor device ( 17 ) comprises an ultrasonic measuring device, an X-ray measuring device, a radar measuring device, and/or an electro-magnetic measuring device.   
     
     
         16 . The system ( 1 ) according to  claim 12 , further comprising
 a second thermomechanical sizing block ( 11 . 2 ) arranged between the first thermomechanical sizing block ( 11 ,  11 . 1 ) and the third cooling device ( 14 ).   
     
     
         17 . The system ( 1 ) according to  claim 16 , further comprising
 an intermediate cooling device ( 13 ) arranged between the first thermomechanical sizing block ( 11 ,  11 . 1 ) and the second thermomechanical sizing block ( 11 . 2 ).   
     
     
         18 . The system ( 1 ) according to  claim 12 ,
 wherein the second cooling device ( 9 ) and/or the third cooling device ( 14 ) comprises at least four water tanks that are arranged spaced apart from one another.   
     
     
         19 . The system ( 1 ) according to  claim 16 ,
 wherein the first thermomechanical sizing block ( 11 . 1 ) is of one-, two-, four-, six-, or eight-stand design, and   wherein the second thermomechanical sizing block ( 11 . 2 ) is of one-, two-, four-, six-, or eight-stand design.   
     
     
         20 . The system ( 1 ) according to  claim 12 ,
 wherein the structure-sensor device ( 17 ) is coupled to an open-loop or closed-loop control device for setting
 a temperature in one or more of the second cooling device ( 9 ) and third cooling device ( 14 ), 
 a rolling temperature, and/or 
 a rolling speed 
 in one or more of the first rolling unit ( 5 ), the second rolling unit ( 7 ), and the first thermomechanical sizing block ( 11 ). 
   
     
     
         21 . A method for producing wire-shaped and/or rod-shaped steel ( 3 ) from a long semi-finished steel product ( 2 ) with a yield strength of at least 300 MPa, comprising:
 heating the long steel semi-finished product ( 2 ) to a temperature of at least 900° ° C.;   pre-rolling the heated long steel semi-finished product ( 2 ) in a first rolling unit ( 5 );   re-rolling the long steel semi-finished product ( 2 ) in a second rolling unit ( 7 ) arranged downstream of the first rolling unit ( 5 );   cooling the long steel semi-finished product ( 2 ) in an adjoining second cooling device ( 9 ) to a temperature of at least 850° C.;   subsequently finish-rolling the long steel semi-finished product ( 2 ) to the wire-shaped and/or rod-shaped steel in a first thermomechanical sizing block ( 11 ,  11 . 1 ) arranged downstream of the second cooling device ( 9 );   cooling the wire-shaped and/or rod-shaped steel to a temperature in the range of 400° C. to 850° C. in a third cooling device ( 14 ) adjoining the first thermomechanical sizing block ( 11 ,  11 . 1 );   feeding the wire-shaped and/or rod-shaped steel to a cooling bed, ring-laying, and/or coil-winding device ( 16 ) arranged downstream of the third cooling device ( 14 ); and   directly determining, by a structure-sensor device ( 17 ) arranged in a section between the first thermomechanical sizing block ( 11 ,  11 . 1 ) and the cooling bed, ring-laying, and/or coil-winding device ( 16 ), any martensitic structure present in the thermomechanically rolled long semi-finished steel product ( 2 ) or in the wire-shaped and/or rod-shaped steel ( 3 ) in an ongoing process.   
     
     
         22 . The method according to  claim 21 , further comprising:
 cooling the long semi-finished steel product ( 2 ) in a first cooling device ( 6 ) adjoining the first rolling unit ( 5 ).   
     
     
         23 . A wire-shaped and/or rod-shaped steel ( 3 ), produced according to the method in accordance with  claim 21 ,
 wherein the wire-shaped and/or rod-shaped steel ( 3 ) has a yield strength of at least 300 MPa and a proportion of martensite of at most 15.0 A.-%.   
     
     
         24 . The wire-shaped and/or rod-shaped steel ( 3 ) according to  claim 23 , comprising the following chemical composition in % by weight: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   Carbon: 
                   0.04 to 0.35 
                 
                     
                   Silicon: 
                   0.10 to 0.80 
                 
                     
                   Manganese: 
                   0.40 to 1.60 
                 
                     
                   Phosphorus: 
                   maximum 0.06 
                 
                     
                   Sulfur: 
                   maximum 0.06 
                 
                     
                   Nitrogen: 
                   maximum 0.012 
                 
                     
                     
                 
                     
                   a balance being residual iron, further accompanying elements, and unavoidable impurities. 
                 
             
                
               
               
                
                
                
                
                
                
                
                
               
            
           
         
       
     
     
         25 . The wire-shaped and/or rod-shaped steel ( 3 ) according to  claim 23 , having a carbon equivalent (Ceq) of ≤0.60.