Method of and for producing heavy plates

Abstract

In the context of a method for producing heavy plate ( 4 ) from a steel alloy, comprising the continuous casting of a steel melt and primary forming of an obtained casting strand to produce a slab, and then forming or hot rolling the slab from the casting heat in multiple forming steps to produce a desired heavy plate dimension, followed immediately by a heat treatment of the heavy plate ( 4 ), effecting a targeted cooling of the obtained heavy plate ( 4 ), wherein the heavy plate ( 4 ) is cut to a desired individual plate length before or after its heat treatment as seen in the production direction ( 3 ), a solution is provided for producing heavy plate that permits the flexible production of heavy plate of variable qualities. This is achieved by carrying out the heat treatment in the temperature range of 150° C.-1100° C. as a combination of a targeted cooling of the obtained heavy plate ( 4 ) from the rolling heat to a desired first temperature, followed immediately by a targeted heating of the heavy plate ( 4 ) to a desired second temperature and an immediately subsequent cooling of the heavy plate ( 4 ) to a desired third temperature.

1 - 17 . (canceled) 
     
     
         18 . A method of producing heavy plates from a steel alloy, comprising the steps of continuous casting of a steel melt and primary forming of an obtained casting strand to produce a slab, and then forming or hot rolling the slab from the casting heat in multiple forming steps to produce a desired heavy plate dimension, followed immediately by a heat treatment of the heavy plate ( 4 ) that effects a targeted cooling of the obtained heavy plate ( 4 ), wherein the heavy plate ( 4 ) is cut to a desired individual plate length before or after its heat treatment as viewed in the direction of production ( 3 ), and the heat treatment is carried out immediately from the rolling heat in the temperature range of 150° C.-1100° C. as a combination of a targeted cooling of the obtained heavy plate ( 4 ) from the rolling heat to a desired first temperature, followed immediately by a targeted heating of the heavy plate ( 4 ) to a desired second temperature, and an immediately subsequent cooling of the heavy plate ( 4 ) to a desired third temperature,
 characterized in that, after forming or hot rolling, the heavy plate ( 4 ) is cooled in the immediately subsequent heat treatment step from the rolling heat to the first desired temperature, which is below the full transformation temperature of γ-iron (γ mixed crystal; austenite) to α-iron (α mixed crystal; ferrite), and is then heated to the desired second temperature, the normal annealing temperature, which is above the full transformation temperature of γ-iron to α-iron, the AC3 temperature, in the temperature range for homogeneous austenite, and finally is cooled to the ambient temperature as the desired third temperature, 
 or in that, after forming or hot rolling, the heavy plate ( 4 ) is cooled in the immediately subsequent heat treatment step from the rolling heat to the first desired temperature, which is below the martensite formation temperature, after which it is heated by heating to a tempering temperature that is below the transformation temperature of γ-iron to α-iron, the Ac1 temperature, as the desired second temperature, and finally is cooled to the ambient temperature as the desired third temperature, 
 or in that, after forming or hot rolling, the heavy plate ( 4 ) is cooled in the immediately subsequent heat treatment step from the rolling heat to the first desired temperature, which is below the bainite formation temperature, after which it is held by heating at a temperature that is within the bainite transformation range as the desired second temperature, and is finally cooled to the ambient temperature as the desired third temperature. 
 
     
     
         19 . The method according to  claim 18 , characterized in that the final cooling to the ambient temperature as the desired third temperature is carried out as air cooling. 
     
     
         20 . The method according to  claim 18 , characterized in that the cooling of the heavy plate ( 4 ) from the rolling heat to the first desired temperature in the heat treatment step immediately following the forming or hot rolling of the heavy plate ( 4 ) is carried out by means of forced water or air cooling. 
     
     
         21 . The method according to  claim 18 , characterized in that a portion of the heat treatment, which comprises in particular additional cooling and/or heating steps, is carried out after the heavy plate ( 4 ) has passed through a straightening unit ( 6 ) and before it is stacked. 
     
     
         22 . The method according to  claim 18 , characterized in that after being heated to the desired second temperature, the heavy plate ( 4 ) is straightened and then stacked. 
     
     
         23 . The method according to  claim 18 , characterized in that in the multiple forming steps, a heavy plate ( 4 ) having a thickness greater than 8 mm, in particular a thickness of 40 mm-400 mm, and a width greater than 1200 mm is produced. 
     
     
         24 . An apparatus ( 1 ,  1 ′) for producing heavy plates from a steel alloy, comprising a casting machine ( 8 ) for the immediately consecutive processing and/or machining of a steel melt in which the steel melt can be continuously cast, a primary forming unit ( 9 ) in which a casting strand cast from the steel melt can be formed into a slab, a forming unit or rolling mill ( 11 ) in which the slab can be rolled from the casting heat in multiple forming steps to form a heavy plate ( 4 ) having the desired heavy plate dimensions, and a heat treatment unit ( 5 ) and a heavy plate cutting device ( 2 ) disposed upstream or downstream of the heat treatment unit ( 5 ) in the direction of production ( 3 ), wherein the heat treatment unit ( 5 ) allows a heavy plate ( 4 ) to be fed to a heat treatment immediately from the rolling heat and comprises at least one cooling device ( 12 ) and at least one heating device ( 13 ), and is designed to be used for carrying out a heat treatment of the heavy plate ( 4 ) within a temperature range of 150° C.-1100° C. in the form of a combination of a targeted cooling of the obtained heavy plate ( 4 ) from the rolling heat to the desired first temperature, followed immediately by a targeted heating of the heavy plate ( 4 ) to the desired second temperature and an immediately subsequent cooling of the heavy plate ( 4 ) to the desired third temperature, characterized in that the heavy plate ( 4 ) that is fed in can be treated variably by means of the heat treatment unit ( 5 ), wherein heavy plate ( 4 ) that is fed in may be cooled by the at least one cooling device ( 12 ) to a temperature below the Ac1 temperature for the steel alloy in question or to a temperature below the temperature that characterizes the start of transformation to a martensite structure for the steel alloy in question, or to a temperature between the temperature that characterizes the start of bainite transformation and the temperature that characterizes the start of transformation to a martensite structure for the steel alloy in question as the desired first temperature, and by means of the at least one heating device ( 13 ), the heavy plate ( 4 ) that has been cooled to the temperature below the Ac1 temperature for the steel alloy in question may be heated to a temperature that is above the AC3 temperature for the steel alloy in question, and the heavy plate ( 4 ) that has been cooled to the temperature below the temperature that characterizes the start of transformation to a martensite structure may be heated to a temperature that is below the Ac1 temperature for the steel alloy in question as the desired second temperature, and the heavy plate ( 4 ) that has been cooled to a temperature that is between the temperature that characterizes the start of bainite transformation and the temperature that characterizes the start of transformation to a martensite structure may be held within this temperature range as the second temperature. 
     
     
         25 . The apparatus ( 1 ,  1 ′) according to  claim 24 , characterized in that the cooling of the heavy plate ( 4 ) to the desired third temperature is carried out at least partially outside of the heat treatment unit ( 5 ). 
     
     
         26 . The apparatus ( 1 ,  1 ′) according to  claim 24 , characterized in that the heat treatment unit ( 5 ) is designed such that, after forming or hot rolling, in an immediately subsequent heat treatment step, the heavy plate ( 4 ) can be cooled by means of the cooling device ( 12 ) from the rolling heat to the first desired temperature, which is below the full transformation temperature of γ-iron (γ mixed crystal; austenite) to α-iron (α mixed crystal; ferrite), in that the heavy plate ( 4 ) can then be heated by means of the heating device ( 13 ) to the desired second temperature, the normal annealing temperature, which is above the full transformation temperature of γ-iron to α-iron, the AC3 temperature, in the temperature range for homogeneous austenite, and in that finally, the heavy plate ( 4 ) can be cooled to the ambient temperature as the desired third temperature. 
     
     
         27 . The apparatus ( 1 ,  1 ′) according to  claim 24 , characterized in that the heat treatment unit ( 5 ) is designed such that, after forming or hot rolling, in an immediately subsequent heat treatment step, the heavy plate ( 4 ) can be cooled by means of the cooling device ( 12 ) from the rolling heat to the first desired temperature, which is below the bainite formation temperature, in that the heavy plate ( 4 ) can then be heated by means of the heating device ( 13 ) and held at a temperature that is within the bainite transformation range as the desired second temperature, and in that finally, the heavy plate ( 4 ) can be cooled to the ambient temperature as the desired third temperature. 
     
     
         28 . The apparatus ( 1 ,  1 ′) according to  claim 24 , characterized in that the heat treatment unit ( 5 ) is designed such that, after forming or hot rolling, in the immediately subsequent heat treatment step, the heavy plate ( 4 ) can be cooled by means of the cooling device ( 12 ) from the rolling heat to the first desired temperature, which is below the martensite formation temperature, in that the heavy plate ( 4 ) can then be heated by means of the heating device ( 13 ) to a tempering temperature that is below the transformation temperature of γ-iron to α-iron, the Ac1 temperature, as the desired second temperature, and in that finally, the heavy plate ( 4 ) can be cooled to the ambient temperature as the desired third temperature. 
     
     
         29 . The apparatus ( 1 ,  1 ′) according to  claim 24 , characterized in that it is designed and configured to produce a heavy plate ( 4 ) having a thickness greater than 8 mm, in particular a thickness of 40 mm-400 mm, and a width greater than 1200 mm in the plurality of forming steps of the rolling mill ( 11 ). 
     
     
         30 . The apparatus ( 1 ,  1 ′) according to  claim 24 , characterized in that it comprises a straightening unit ( 6 ) disposed downstream of the heating device ( 13 ) in the direction of production ( 3 ) of the heavy plate ( 4 ). 
     
     
         31 . The apparatus ( 1 ,  1 ′) according to  claim 30 , characterized in that it comprises one or more additional heat treatment unit(s) disposed downstream of the straightening unit ( 6 ) in the direction of production ( 3 ) of the heavy plate ( 4 ), each of said units preferably comprising at least one additional cooling device and at least one additional heating device.