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EP4351812A1 - Procédé de fabrication d'un acier micro-allié, acier micro-allié produit à l'aide du procédé et installation combinée de coulée/laminage - Google Patents

Procédé de fabrication d'un acier micro-allié, acier micro-allié produit à l'aide du procédé et installation combinée de coulée/laminage

Info

Publication number
EP4351812A1
EP4351812A1 EP22730486.2A EP22730486A EP4351812A1 EP 4351812 A1 EP4351812 A1 EP 4351812A1 EP 22730486 A EP22730486 A EP 22730486A EP 4351812 A1 EP4351812 A1 EP 4351812A1
Authority
EP
European Patent Office
Prior art keywords
rolled strip
stand
finished rolled
rolling
stand group
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP22730486.2A
Other languages
German (de)
English (en)
Inventor
Kerstin Baumgartner
Simon Grosseiber
Thomas Lengauer
Gero Schwarz
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Primetals Technologies Austria GmbH
Original Assignee
Primetals Technologies Austria GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Primetals Technologies Austria GmbH filed Critical Primetals Technologies Austria GmbH
Publication of EP4351812A1 publication Critical patent/EP4351812A1/fr
Pending legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
    • B22D11/0408—Moulds for casting thin slabs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/12—Accessories for subsequent treating or working cast stock in situ
    • B22D11/1206—Accessories for subsequent treating or working cast stock in situ for plastic shaping of strands
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/12—Accessories for subsequent treating or working cast stock in situ
    • B22D11/124—Accessories for subsequent treating or working cast stock in situ for cooling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16—Controlling or regulating processes or operations
    • B22D11/22—Controlling or regulating processes or operations for cooling cast stock or mould
    • B22D11/225—Controlling or regulating processes or operations for cooling cast stock or mould for secondary cooling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/62—Quenching devices
    • C21D1/667—Quenching devices for spray quenching
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D11/00—Process control or regulation for heat treatments
    • C21D11/005—Process control or regulation for heat treatments for cooling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/021—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips involving a particular fabrication or treatment of ingot or slab
    • C21D8/0215—Rapid solidification; Thin strip casting
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/54—Furnaces for treating strips or wire
    • C21D9/56—Continuous furnaces for strip or wire
    • C21D9/573—Continuous furnaces for strip or wire with cooling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/54—Furnaces for treating strips or wire
    • C21D9/56—Continuous furnaces for strip or wire
    • C21D9/573—Continuous furnaces for strip or wire with cooling
    • C21D9/5735—Details
    • C21D9/5737—Rolls; Drums; Roll arrangements
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
    • B21B1/463—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting in a continuous process, i.e. the cast not being cut before rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/34—Methods of heating
    • C21D1/42—Induction heating
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/004—Dispersions; Precipitations
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2261/00—Machining or cutting being involved
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/54—Furnaces for treating strips or wire
    • C21D9/56—Continuous furnaces for strip or wire
    • C21D9/60—Continuous furnaces for strip or wire with induction heating

Definitions

  • the invention relates to a method for producing a micro-alloyed steel according to patent claim 1, a micro-alloyed steel according to patent claim 12 and a combined casting and rolling plant according to patent claim 14.
  • a roll stand with a stand cooler for cooling a steel strip is known from WO 2019/020492 A1.
  • US 2016/151814 A1 discloses a system and a method for hot-rolling a steel strip.
  • cooling of a metal strip in a roller frame is known from WO 2020/126473 A1.
  • AT 512 399 B1 discloses a method for producing a micro-alloyed tubular steel in a combined casting and rolling plant.
  • thin slab strands continuously cast strands with a thickness of ⁇ 150 mm are referred to as thin slab strands.
  • the rigid thin slab strand is supported, deflected and cooled.
  • the thin slab strand is rolled into a pre-rolled strip in the pre-rolling mill.
  • the first stand group of the finishing train finishes the pre-rolled strip into the finished rolled strip.
  • the finish-rolled finished rolled strip is fed to the second stand group and in the second stand group the finished rolled strip is forcibly cooled while maintaining a thickness of the finished rolled strip in such a way that a cooling speed of a core of the finished rolled strip in the second stand group is greater than 20° C./s and less is 200°C/s.
  • micro-alloyed steel can be produced in a simple manner.
  • a microalloyed steel can also be produced with a metallic melt with 10% fewer microalloying elements (e.g. titanium, niobium and/or vanadium), which corresponds, for example, to an X60 to X120 steel according to the API 5L/IS03183:2007 standard which meets the mechanical requirements for the steel grades according to the standard mentioned.
  • the microalloyed steel can thus be produced particularly simply and inexpensively by the method.
  • a continuously produced strand of thin slab is rough-rolled and finish-rolled uncut and the micro-alloyed steel is cut to the length of the coil for the first time after it has passed through the cooling section.
  • the second group of stands has a second finishing rolling stand, with the second finishing rolling stand being converted into the stand cooler in a preparatory step before the molten metal is poured, in that at least one work roll of the second finishing rolling stand is removed and at least one cooling beam is moved to the second Finishing rolling stand is used.
  • a third surface temperature at which the finished rolled strip leaves the second stand group is determined. The forced cooling in the second stand group is controlled and/or regulated as a function of the third surface temperature and a third target temperature in such a way that the third surface temperature essentially corresponds to the third target temperature.
  • the third setpoint temperature is lower than a ferrite-pearlite transformation temperature, preferably lower than a bainite start temperature, in particular lower than a martensite start temperature.
  • a second surface temperature at which the finished rolled strip leaves the first stand group is determined.
  • the second surface temperature is also taken into account when controlling the forced cooling of the finished rolled strip in the second stand group.
  • the cooling rate of the core of the finished rolled strip is 20° C./s to 80° C./s, in particular 45° C./s to 55° C./s. It is advantageous if the cooling takes place continuously. This ensures that a high-strength e.g. bainitic and/or martensitic micro-alloyed steel can be produced.
  • the core of the finish-rolled finish-rolled strip is transported into the second stand group of the finishing train at a first exit temperature of 830° C. to 950° C., in particular from 880° C. to 920° C.
  • the core of the finished rolled strip has a second exit temperature of less than 700°C, in particular from 350°C to 700°C, preferably from 400°C to 460°C.
  • the core of the finished rolled strip is cooled from the first exit temperature to the second exit temperature, preferably continuously, in a time interval of 2 seconds to 40 seconds.
  • the finished rolled strip occurs within a time interval of 1 second to 15 seconds after the finish rolling of the finish rolled strip in the first stand group finished strip into the second stand group. Due to the short time interval, the finished rolled strip is cooled down from a particularly high first exit temperature. Furthermore, unwanted cooling of the finished rolled strip between the first group of stands and the second group of stands is kept particularly low.
  • the combined casting-rolling system has a cooling section downstream of the finishing train in relation to a conveying direction of the finished rolled strip and a coiler device downstream of the cooling section. Forced cooling of the finished rolled strip in the cooling section is deactivated and the finished rolled strip is transported through the cooling section from the second stand group to the coiler. This allows the finished rolled strip to dry in the cooling line, so that the finished rolled strip is coiled dry into a coil. Furthermore, wear and tear on the cooling line is reduced and this minimizes the maintenance effort for the cooling line.
  • the grain size of the pre-rolled strip when it leaves the pre-rolling train is 10 ⁇ m to 30 ⁇ m.
  • the grain size of the pre-rolled strip between the pre-rolling train and the entry into the first stand group increases to 20 ⁇ m to 60 ⁇ m or the grain size remains the same.
  • the grain size of the finished rolled strip is reduced to 2 ⁇ m to 20 ⁇ m during rolling in the first stand group.
  • the structure has a "pancake structure" when the finished strip emerges from the first group of stands.
  • the grain size can be determined on the cooled pre-rolled strip 110 and/or cooled finished rolled strip 145 in a cross section at a normal angle to the conveying direction, for example by means of light microscopy and, for example, according to IS0643 in a strip center (both in width and thickness) of the respective strip.
  • the grain size of the pre-rolled strip between the pre-rolling train and the finishing train and/or the finishing rolled strip can be calculated, for example, using a mathematical model.
  • An exemplary mathematical model is, for example, from ISIJ International, Vol. 32 (1992), no. 12, pages 1329 to 1338, published under the title "A Mathematical Model to Predict the Mechanical Properties of Hot Rolled C-Mn and Microalloyed Steels".
  • the thickness of the pre-rolled strip when it enters the first stand group is 40 mm to 62 mm, in particular 45 mm.
  • the first stand group reduces the thickness of the pre-rolled strip to 10 mm to 25 mm, in particular 16 mm to 20 mm. This thickness is particularly suitable for the manufacture of tubes from the micro-alloyed steel.
  • the metallic melt has a chemical composition in weight percent of C 0.025-0.05%; Si 0.1-0.3%; Mn 0.07-1.5%, Cr ⁇ 0.15%; Mo ⁇ 0.2%; Nb 0.02-0.08%; Ti ⁇ 0.05%;V ⁇ 0.08%;N ⁇ 0.008%; remainder Fe and unavoidable impurities.
  • the process reduces the limits of carbon, silicon and chromium. Molybdenum can be added to increase strength.
  • the metallic melt for X80 to X120 steels in particular for X90 to X120 steels, preferably has a chemical composition in weight percent of C 0.025-0.09%; Si 0.1-0.3%; Mn 0.07-2.0%, Cr ⁇ 0.5%; Mo ⁇ 0.5%; Nb 0.02-0.08%; Ti ⁇ 0.05%; V ⁇ 0.08%; Ni ⁇ 0.5%; Cu ⁇ 0.4%; N ⁇ 0.01%; Balance Fe and unavoidable impurities.
  • micro-alloyed steel in particular micro-alloyed pipe steel with a thickness of 10 mm to 25 mm, in particular 16 mm to 20 mm, can be produced by means of the method described above.
  • the microalloyed steel for a X60 or a X70 steel preferably has a chemical composition in weight percent of C 0.025-0.05%; Si 0.1-0.3%; Mn 0.07-1.5%, Cr ⁇ 0.15%; Mo ⁇ 0.2%; Nb 0.02-0.08%; Ti ⁇ 0.05%; V ⁇ 0.08%; N ⁇ 0.008%; remainder Fe and unavoidable impurities.
  • the microalloyed steel for X80 to X120 steels preferably has a chemical composition in weight percent of C 0.025-0.09%; Si 0.1-0.3%; Mn 0.07-2.0%, Cr ⁇ 0.5%; Mo ⁇ 0.5%; Nb 0.02-0.08%; Ti ⁇ 0.05%; V ⁇ 0.08%; Ni ⁇ 0.5%; Cu ⁇ 0.4%; N ⁇ 0.01%; Balance Fe and unavoidable impurities.
  • the microalloyed steel advantageously has at least one of the following precipitates at room temperature: Ti(C,N), Nb(C,N) V(C,N) TiC, TiN, Ti(C,N), (Nb,Ti)C , (Nb,Ti)N, (Nb,Ti)(C,N), NbC, NbN, VC, VN, V(C,N), (Nb,Ti,V)(C,N), (Nb, V)C, (Ti,V)C, (Nb,V)(C,N), (Ti,V)(C,N), (Nb,V)N, (Ti,V)N, (Nb, Ti,V)C, (Nb,Ti,V)N.
  • a precipitation density of the precipitations is 10 2 °-10 23 1/m 3 , the precipitations having an average size of 1 nm to 15 nm.
  • the precipitation density and/or the average size can preferably be determined by means of transmission electron microscopy (TEM), with a precipitation size for determining the average size of the precipitations transverse to a conveying direction of the finished rolled strip and perpendicular to a cross section of the finished rolled strip being preferably determined.
  • TEM transmission electron microscopy
  • an improved casting-rolling compound plant for the production of a micro-alloyed steel can be provided by the casting-rolling compound plant being a continuous casting machine with a mold, a single-stand or multi-stand roughing train and a finishing train with at least one first scaffold group and a second scaffold group.
  • a metallic melt can be cast in the mold to form a partially solidified thin slab strand and the thin slab strand can be fed to the pre-rolling train.
  • the roughing train is designed to roll the completely solidified thin slab strand into a pre-rolled strip, with the pre-rolled strip being able to be fed to the finishing rolling train.
  • the first stand group is designed to finish-roll the pre-rolled strip into a finish-rolled strip.
  • the second stand group is arranged downstream of the first stand group and has at least one stand cooler.
  • the second stand group is designed to forcibly cool the finished rolled strip while maintaining a thickness of the finished rolled strip such that a cooling speed of a core of the finished rolled strip in the second stand group is greater than 20° C./s and less than 200° C./s.
  • the combined casting and rolling plant which works, for example, in continuous operation and usually produces conventional finished steel strips, it can be used in a simple manner to produce finished rolled strips with micro-alloyed steel, in particular with micro-alloyed tubular steel.
  • the combined casting and rolling plant can be used flexibly to cast thin sheets with a thickness of 0.8 mm to 2.5 mm and the finished rolled strip made of micro-alloyed steel with the above-mentioned thickness of 8 mm to 25 mm to produce.
  • the compound casting-rolling system has a cooling section downstream of the second stand group in relation to the conveying direction of the finished rolled strip and a coiler device downstream of the cooling section.
  • forced cooling of the finished rolled strip in the second stand group forced cooling of the finished rolled strip in the cooling section is deactivated.
  • the cooling section is exclusively designed to transport the finished rolled strip to the coiler and preferably to dry the finished rolled strip. This configuration has the advantage that the combined casting and rolling facility can be operated in a particularly energy-efficient manner. Furthermore, the finished rolled strip can be coiled up dry, so that corrosion of the finished rolled strip is avoided.
  • the compound casting-rolling plant has a third temperature measuring device and a control unit, the third temperature measuring device and the second stand group being connected to the control unit in terms of data technology.
  • the third temperature measuring device is related to the conveying direction of the finished rolled strip arranged between the second stand group and the cooling section and is designed to determine a third surface temperature of the finished rolled strip.
  • the control unit is designed to control the forced cooling of the second stand group on the basis of the determined third surface temperature of the finished rolled strip and a predefined third setpoint temperature.
  • FIG. 1 shows a schematic representation of a combined casting and rolling plant according to a first embodiment
  • FIG. 2 shows a flow chart of a method for operating the system shown in FIG.
  • FIG. 3 shows a first diagram of a core temperature in the production of a finished rolled strip plotted over time
  • FIG. 4 shows a first section A, marked in FIG. 3, of the first diagram shown in FIG. 3;
  • FIG. 5 shows a second section B, marked in FIG. 3, of the first diagram shown in FIG. 3;
  • FIG. 6 shows a second diagram of a course of a grain size in the manufacture of the finished rolled strip, plotted over time
  • FIG. 8 shows a schematic representation of a combined casting and rolling plant according to a second embodiment.
  • FIG. 1 shows a schematic representation of a combined casting and rolling system 10 according to a first embodiment.
  • the combined casting and rolling facility 10 has, for example, a continuous casting machine 15, a roughing train 20, a first to third separating device 25, 30, 35, and an intermediate heating system 40, preferably a descaler 45, a finishing train 50, a cooling section 55, a coiler 60 and a control unit 65.
  • the combined casting and rolling system 10 can have a first to third temperature measuring device 70, 75, 80, for example a pyrometer.
  • the continuous casting machine 15 is embodied as a curved strand machine, for example.
  • the continuous casting machine 15 has a ladle 85 , a distributor 86 and a mold 90 .
  • the distributor 86 is filled with a metallic melt 95 by means of the ladle 85 .
  • the metallic melt 95 can be produced, for example, by means of a converter, for example in a Linz-Donawitz process.
  • the metallic melt 95 is, for example, a steel melt.
  • the metallic melt 95 flows from the distributor 86 into the mold 90. In the mold 90, the metallic melt 95 is cast into a thin slab strand 100.
  • the partially solidified thin slab strand 100 is pulled out of the mold 90 and, due to the design of the continuous casting machine 15 as a curved continuous casting machine, is deflected in an arc into a horizontal line, supported and solidified in the process.
  • the thin slab strand 100 is conveyed away from the mold 90 in the conveying direction.
  • the continuous casting machine 15 casts an endless thin slab strand 100 and feeds it to a roughing train 20 downstream in the conveying direction of the thin slab strand 100 .
  • the roughing train 20 follows directly the continuous casting machine 15.
  • the roughing train 20 can have one or more roughing stands 105 which are arranged one behind the other in the conveying direction of the thin slab strand 100 .
  • the number of roughing stands 105 can essentially be freely selected and is essentially dependent on the format of the thin slab strand 100 and on a desired thickness of the roughing strip 110.
  • the embodiment example shows three roughing stands 105 for the roughing train 20 shown in FIG intended.
  • the roughing train 20 is designed to roll the thin bram strand 100, which is hot when it is fed into the roughing train 20, into a pre-rolled strip 110.
  • the first and second separating devices 25, 30 are arranged downstream of the roughing train 20 in relation to the conveying direction of the pre-rolled strip 110.
  • the second separating device 30 is arranged at a distance from the roughing train 20 in relation to the conveying direction of the pre-rolled strip 110 .
  • a discharge device can be arranged between the first separating device 25 and the second separating device 30 .
  • On the second Separating device 30 can also be omitted.
  • the first and/or second separating device 25, 30 can be designed, for example, as drum shears or pendulum shears.
  • the combined casting and rolling plant 10 can be operated in continuous operation, i.e. the thin slab strand enters the roughing train 105 uncut, the roughing strip passes through the first and/or second cutting device uncut and the roughing strip is finish-rolled uncut in the finishing train 50 and is only cut to coil length after passing through the cooling section 55 .
  • the intermediate heating 40 follows the second cutting device 30.
  • the intermediate heating 40 is designed, for example, as an induction furnace. A different configuration of the intermediate heater 40 would also be possible.
  • the intermediate heater 40 is arranged upstream of the finishing train 50 and the descaler 45 with respect to the conveying direction of the pre-rolled strip 110 .
  • the descaler 45 is arranged directly upstream of the finishing train 50 and downstream of the intermediate heater 40 .
  • the finishing train 50 has a first stand group 115 and a second stand group 120 in the embodiment.
  • the first stand group 115 is arranged upstream of the second stand group 120 in relation to the conveying direction of the pre-rolled strip 110 .
  • the first group of stands 115 can have, for example, two to four first finishing rolling stands 125 .
  • the first finishing stands 125 are arranged one behind the other in relation to the conveying direction of the roughing strip 110 .
  • the first stand group 115 directly follows the descaler 45 in relation to the conveying direction of the pre-rolled strip 110, if the descaler 45 is provided. If the descaler 45 is dispensed with, the first stand group 115 is directly connected to the intermediate heater 40 .
  • the second group of stands 120 has at least one, preferably two, second finishing rolling stands 130, with the first finishing rolling stand 125 and the second finishing rolling stand 130 being able to be constructed identically.
  • the second finishing rolling stand 130 has the option of being converted into a stand cooler 135 at least in addition.
  • the two second finishing stands 130 are each converted into a stand cooler 135 .
  • the second finishing stand 130 no longer carries out a rolling process.
  • the second stand group 120 can have at least one intermediate cooler 140 .
  • the intermediate cooler 140 can be arranged between two finishing rolling stands 125, 130, respectively.
  • the second stand group 120 has, for example, two intermediate coolers 140, with a first of the two intermediate coolers 140 being arranged, for example, between the last first finishing rolling stand 125 of the first rolling stand group 115 in the conveying direction and the second finishing rolling stand 130 arranged first in the conveying direction.
  • a further intermediate cooler 140 can also be arranged between the two second finishing rolling stands 130 .
  • the intercoolers 140 can also be dispensed with, or only one of the two intercoolers 140 can be provided.
  • the second finishing stand 130 is converted to the stand cooler 135 in the embodiment.
  • the conversion option can be implemented in that the second finishing rolling stand 130 has a changing device (not shown).
  • the changing device fastens at least one chock and an upper and/or lower work roll 141, 142 (shown in dashed lines in FIG. 1) in the second finishing rolling stand 130.
  • the configuration as a second rolling stand with At least the upper and/or lower work roll 141 , 142 is configured in the second finishing rolling stand 130 for rolling the pre-rolled strip 110 .
  • the changing device fastens means for cooling a finishing rolled strip 145 instead of the chock and the lower and/or upper work roll 141, 142.
  • the chock and the upper and/or lower work roll 141, 142 have been removed .
  • the design of the second finishing rolling stand 130 as a stand cooler 135 and the means provided for cooling the finishing rolled strip 145 will be discussed below.
  • the second finishing mill stand 130 can be converted quickly and easily between the second mill stand for rolling the pre-rolled strip 110 and the stand cooler 135 .
  • the framework cooler 135 and the intermediate cooler 140 each have at least one cooling beam as a means for cooling.
  • the cooling beams of the stand cooler 135 and/or the intermediate cooler 140 are each preferably arranged both on the upper side and on the lower side of the finished rolled strip 145 in order to cool the finished rolled strip 145 particularly quickly and effectively on both sides.
  • the cooling beam is fastened in the stand cooler 135 by means of the changing device instead of the upper and/or lower work roll 141 , 142 .
  • a total of, for example, 16 cooling beams can be provided by the embodiment shown in FIG.
  • each stand cooler 135 can have two cooling bars arranged on the upper side and two cooling bars arranged on the underside of the finished rolled strip 145 .
  • this configuration is an exemplary configuration of the second skeleton group 120 .
  • the second stand group 120 it would also be conceivable for the second stand group 120 to be designed differently.
  • at least one of the intermediate coolers 140 can be dispensed with.
  • a different arrangement of the intermediate cooler(s) 140 would also be conceivable.
  • the arrangement and/or number of chilled beams is also an example. In one development, the number of chilled beams can be increased or decreased. It is also conceivable that the cooling beams are arranged only on the top or bottom of the finished rolled strip 145 .
  • the upper and/or lower work rolls 141 , 142 are dismantled in order to create sufficient installation space for the cooling beams in the second finishing rolling stand 130 converted into the stand cooler 135 .
  • the first finishing rolling stands 125 finish-roll the pre-rolled strip 110 fed into the first stand group 115 to form the finished rolled strip 145 .
  • the cooling section 55 is arranged downstream of the finishing train 50 in relation to a conveying direction of the finished rolled strip 145 .
  • the third separating device 35 is arranged downstream of the cooling section 55 in the conveying direction of the finished rolled strip 145 . In this case, the third separating device 35 is arranged between the coiling device 60 and the cooling section 55 .
  • the third separating device 35 can be designed, for example, as drum shears or pendulum shears.
  • the control device 65 has a control device 150 , a data memory 155 and an interface 160 .
  • the data memory 155 is connected in terms of data technology to the control device 150 by means of a first data connection 165 .
  • the interface 160 is also connected in terms of data technology to the control device 150 by means of a second data connection 170 .
  • a predefined first setpoint temperature, a predefined second setpoint temperature and a predefined third setpoint temperature TS3 are stored in the data memory 155 . Furthermore, a method for producing the microalloyed steel is stored in the data memory 155, on the basis of which the control device 150 controls the components of the combined casting and rolling system 10 .
  • the interface 160 is connected to the intermediate heater 40 by means of a third data connection 175 .
  • a fourth data connection 180 connects the finishing train 50 with the interface 160 in terms of data technology.
  • a fifth data connection 185 connects the cooling section 55 with the interface 160.
  • the temperature measuring device 70, 75, 80 is connected via an assigned sixth to eighth data connection 190, 195, 200 with the interface 160 connected in terms of data technology.
  • further data links (not shown in FIG. 1) to the other components of the combined casting and rolling system 10 can be provided, so that an exchange of information between the various components of the combined casting and rolling system 10 and the control unit 65 is possible.
  • the third to eighth data connection 175, 180, 185, 190, 195, 200 can be part of an industrial network, for example.
  • FIG. 2 shows a flow chart of a method for operating the compound casting/rolling system 10 shown in FIG.
  • the second finishing rolling stands 130 or the second finishing rolling stand 130 of the second stand group 120 are converted to the configuration as a stand cooler 135 in a preparatory step.
  • the upper and/or lower work roll 141, 142 can be removed from the second finishing rolling stand 130 by opening the changing device and replaced by the cooling beams.
  • the cooling beam can be aligned in such a way that it is directed directly in the direction of a passage through which the finished rolled strip 145 is fed.
  • the cooling beams are fastened in the framework cooler 135 .
  • the structure of the compound casting/rolling system 10 shown in FIG. 1 no longer corresponds to the conventional structure of a compound casting/rolling system, but deviates from its structure.
  • the combined casting and rolling facility 10 is no longer suitable for producing a thin finished rolled strip 145 with a thickness of 0.8 mm to 8 mm.
  • the preparation step is carried out before the production process for producing the microalloy steel is produced.
  • FIG. 3 shows a first diagram of a core temperature of a core of the finished rolled strip 145 in the manufacture of the finished rolled strip 145 plotted against a time t.
  • FIG. 4 shows a first section A, marked in FIG. 3, of the first diagram shown in FIG.
  • FIG. 5 shows a second section B, marked in FIG. 3, of the first diagram shown in FIG. 6 shows a second diagram of a course of a grain size K in the Production of the finished rolled strip 145 plotted over time t.
  • FIGS. 2 to 6 are explained together. In order to mark individual method steps in FIGS. 3 to 7, the respective reference number of the associated method step is indicated in FIGS. 3 to 7.
  • a first graph 400 and a second graph 405 are plotted in FIG.
  • the first graph 400 shows the temperature profile of the core when the method described below for FIG. 2 is carried out.
  • the second graph 405 shows a temperature profile of the core when the finished rolled strip 145 with the above-specified thickness of 10 mm to 25 mm is produced by means of the combined casting and rolling plant 10 shown in FIG .
  • the mold 90 (shown in FIG. 1) of the continuous casting machine 15 is closed with a dummy bar head (not shown in FIG. 1) in a first process step 305 and sealed with additional sealing material.
  • the metallic melt 95 is poured into a distributor of the continuous casting machine 15.
  • a plug is removed from a shroud of the continuous casting machine 15 .
  • the metallic melt 95 has a chemical composition in weight percent of C 0.025-0.05% for a X60 or a X70 steel; Si 0.1-0.3%; Mn 0.07-1.5%, Cr ⁇ 0.15%; Mo ⁇ 0.2%; Nb 0.02-0.08%; Ti ⁇ 0.05%; V ⁇ 0.08%; N ⁇ 0.008%; remainder Fe and unavoidable impurities.
  • the metallic melt 95 may preferably have a chemical composition in weight percent of C 0.025-0.09% for X80 to X120 steels; Si 0.1-0.3%; Mn 0.07-2.0%, Cr ⁇ 0.5%; Mo ⁇ 0.5%; Nb 0.02-0.08%; Ti ⁇ 0.05%; V ⁇ 0.08%; Ni ⁇ 0.5%; Cu ⁇ 0.4%; N ⁇ 0.01%; Remainder Fe and unavoidable impurities.
  • the specification of the steel refers to the API 5L/IS03183:2007 standard.
  • the metallic melt 95 can also have a different chemical composition.
  • the temperatures and process steps specified below relate to the compositions of the steel preferred in the embodiment, in order to cast a microalloyed steel, in particular a microalloyed pipe steel with a steel grade X60 to X120, in particular X90 to X120, using the combined casting and rolling system 10 to the standard API 5L/IS03183:2007.
  • the metallic melt 95 in the mold 90 flows around the dummy bar head and solidifies by cooling in the dummy bar head.
  • the dummy bar head is slowly drawn from the mold 90 of the continuous casting machine 15 in the direction of the roughing road 20.
  • the metal cools Melt 95 in the mold 90 at its contact surfaces with the mold 90 and forms a shell of the thin slab strand 100.
  • the shell encloses a still liquid core and holds the liquid core.
  • the thin slab strand 100 can have a thickness of 100 mm to 150 mm, for example.
  • the continuous casting machine 15 the thin slab strand 100 is deflected and further cooled on the way to the roughing train 20, so that the thin slab strand 100 hardens from the outside to the outside.
  • the continuous casting machine 15 is configured as a curved continuous casting machine, so that the thin slab strand 100 is deflected by essentially 90° from the vertical and the thin slab strand 100 is fed essentially horizontally into the roughing train 20 .
  • the thin slab strand 100 is rolled in the roughing train 20 by the roughing stands 105 to form the roughing strip 110.
  • a structure of the thin slab strand 100 has a grain size K of about 800 ⁇ m to 1000 ⁇ m.
  • the thickness is successively reduced to, for example, 40 mm to 62 mm, in particular 45 mm.
  • the structure of the thin slab strand 100 recrystallizes during hot rolling into the roughing strip 110, so that the structure of the roughing strip 110 when it is fed out of the roughing train 20 is preferably completely recrystallized.
  • the microstructure of the thin slab strand 100 towards the pre-rolled strip 110 is homogenized by the individual hot-rolling steps in the roughing stands 105 .
  • the grain size K can be 10 ⁇ m to 30 ⁇ m when leaving the roughing train.
  • a core temperature T of the core of the thin slab strand 100 upon entry into the roughing train 20 with the chemical compositions mentioned above is approximately 1300 to 1450°C. With each rolling step in the roughing train 20, the core temperature of the core is reduced, so that the roughed strip 110 has a core temperature of approximately 980 to 1150° C. when it exits.
  • a third method step 315 the pre-rolled strip 110 is guided through the first and second cutting device 25, 30, with the pre-rolled strip 110 not being cut off.
  • the first and second separating device 25, 30 is thus only run through fen.
  • the pre-rolled strip 110 cools down further as a result of convection, and the cooling can be reduced by a protective cover.
  • the grain size K in the pre-rolled strip 110 can increase to 20 ⁇ m up to 60 ⁇ m. Also the grain size K, in particular with the chemical compositions mentioned above, of the melt 95 can be retained and not increase.
  • the control device 150 activates the intermediate heater 40 so that the intermediate heater 40, which is designed as an induction furnace, for example, increases the core temperature of the pre-rolled strip 110 from about 870° C. to 980° C. when it enters the intermediate heater 40 1050 °C to 1100 °C (see FIG 3).
  • the grain size K can be kept essentially constant in the structure during heating (cf. FIG. 6).
  • the first temperature measuring device 70 determines a first surface temperature of the pre-rolled strip 110 guided out of the intermediate heating 40.
  • the first temperature measuring device 70 provides first information about the first surface temperature of the pre-rolled strip 110 between the intermediate heating 40 and the descaler 45 via the sixth data connection 190 of the interface 160 ready, which provides the first information of the control device 150.
  • a sixth method step 330 the control device 150 regulates a heating capacity of the intermediate heater 40 such that the determined first surface temperature of the pre-rolled strip 110 between the intermediate heater 40 and the descaler 45 essentially corresponds to the first target temperature.
  • the control device 150 can regularly repeat the fifth and sixth method step 325, 330 in a loop at a predefined time interval.
  • a seventh method step 335 the control device 150 activates the detonator 45 (if present).
  • the descaler 45 descales the pre-rolled strip 110.
  • the pre-rolled strip 110 cools down, for example, by about 80° C. to 100° C. based on the core of the pre-rolled strip 110.
  • the first entry temperature TE1 based on the core of the pre-rolled strip 110, at which the pre-rolled strip 110 enters the first stand group 115 after the descaler 45, can be between 850° C. and 1060° C., in particular between 920° C. and 980° C.
  • the structure of the pre-rolled strip 110 is preferably homogeneously austenitic and recrystallized.
  • the pre-rolled strip 110 is finish-rolled to form the finish-rolled strip 145, for example by means of three first finishing rolling stands 125.
  • the pre-rolled strip 110 to be rolled into the finished rolled strip 145 cools by about 50° C.
  • the thickness of the pre-rolled strip 110 is reduced from, for example, 40 mm to 62 mm, in particular 45 mm, to a thickness of 10 mm to 25 mm, in particular 16 mm to 20 mm, via the three first finishing rolling stands 125 .
  • the three rolling steps in the respective first finishing rolling stands 125 form a “pancake” or a recrystallized austenitic structure in the pre-rolled strip 110 rolled to form the finished rolled strip 145 (cf. FIG. 5).
  • the grain size K when exiting the first framework group 115 is preferably 2 ⁇ m to 20 ⁇ m.
  • a first exit temperature TA1 of the finished rolled strip 145 after passing through the first stand group 115 is preferably 830° C. to 950° C.
  • the first outlet temperature TA1 is 880°C to 920°C.
  • the first exit temperature TA1 is based on the core of the finished rolled strip 145.
  • the grain size can be determined on the cooled pre-rolled strip 110 and/or cooled finished rolled strip 145 in a cross section perpendicular to the conveying direction, for example by means of light microscopy in a strip center (both in width and thickness) of the respective strip.
  • the grain size K of the pre-rolled strip 110 between the roughing train 20 and the finishing train 50 can be calculated using a mathematical model, for example.
  • An exemplary mathematical model is, for example, from ISIJ International, Vol. 32 (1992), no. 12, pages 1329 to 1338, published under the title "A Mathematical Model to Predict the Mechanical Properties of Hot Rolled C-Mn and Microalloyed Steels".
  • the finish-rolled finish rolled strip 145 is transported further in the direction of the second stand group 120 at the first exit temperature TA1 .
  • the fact that the second group of stands 120 directly adjoins the first group of stands 115 means that the time it takes to exit from the first group of stands 115 and into the second group of stands 120 is minimal.
  • the length of time for example at a conveying speed of 0.4 m/s to 1 m/s, can be only 1 second to 15 seconds due to the direct arrangement of the second stand group 120 downstream of the first stand group 115 .
  • the intermediate cooler 140 adjoining the first scaffolding group 115 can spatially adjoin the first scaffolding group 115 up to a few meters (less than 10 m) up to about 0.5 meters. Due to the spatially small distance between the first stand group 115 and the second stand group 120, the first exit temperature TA1 essentially corresponds to a second entry temperature TE2 at which the finish-rolled finish rolled strip 145 enters the second stand group 120.
  • a second surface temperature of the finished rolled strip 145 coming from the first stand group 115 is determined by means of the second temperature measuring device 75 .
  • the second temperature measuring device 75 provides second information with the first outlet temperature TA1 via the seventh data connection 195 and the interface 160 of the control device 150 .
  • the control device 150 can also take the second surface temperature into account when controlling the intermediate heater 40 .
  • the second surface temperature correlates with the first outlet temperature TA1, the second surface temperature deviating in value from the first outlet temperature TA1.
  • the intermediate heater 40 is regulated in such a way that the second surface temperature essentially corresponds to a second setpoint temperature.
  • the second temperature measuring device 75 and the tenth method step 350 can also be dispensed with.
  • the control device 150 activates the intermediate cooler 140 and the stand cooler 135.
  • the intermediate cooler 140 and the stand cooler 135 spray a cooling medium, for example water, possibly with an additive, onto the finished rolled strip 145, so that the finished rolled strip 145 in the second Scaffold group 120 is forcibly cooled.
  • the finished rolled strip 145 is guided through the second stand group 120 while maintaining its thickness. Further rolling of the finished rolled strip 145, in which the thickness of the finished rolled strip 145 is reduced, does not take place. If one of the work rolls 141 , 142 remains in the stand cooler 135 , it can be used to support and/or transport the finished rolled strip 145 .
  • the delivery quantity of the cooling medium is selected such that, within the second stand group 120, the finished rolled strip 145 is heated from the second inlet temperature TE2 to a second outlet temperature TA2 of less than 700 °C, in particular from 350 °C to 700 °C, in particular from 400 °C to 460 °C, is cooled within 2 to 40 seconds.
  • the control device 150 controls the delivery quantity of the cooling medium in such a way that a cooling capacity of the second stand group 120 ensures a cooling rate of the core of the finished rolled strip 145 of at least 20° C./s to 200° C./s.
  • the cooling rate is preferably 20° C./s to 80° C./s, in particular 45° C./s to 55° C./s, with the cooling in the core via the second framework group 120 preferably taking place continuously.
  • this cooling speed is ensured by the fact that preferably two intermediate coolers 140 and two stand coolers 135 are provided.
  • about 100 m 3 /h to 300 m 3 /h of the cooling medium can be applied to the finished rolled strip 145 at a pressure of 2 bar to 4 bar per cooling beam of the stand cooler 135 .
  • Each scaffolding cooler 135 can be configured in such a way that a control valve that can be controlled by control device 150 is provided for each cooling beam in order to control them separately from the other cooling beam of intermediate cooler 140 or the other scaffolding cooler 135, preferably steplessly and separately from one another.
  • a volume flow of the cooling medium can be continuously regulated between 0% and 100% by the control device 150 for each chilled beam.
  • the rapid and very early cooling of the finished rolled strip 145 immediately after the first stand group 115 can ensure that the maximum possible cooling rate begins with the high second outlet temperature TE2.
  • a cooling of the finished rolled strip 145 when simply passing through the second stand group 120 and deactivated conveyance of the cooling medium through the second stand groups 120 and cooling that only begins in the cooling section 55 is thereby avoided.
  • the third temperature measuring device 80 determines a third surface temperature, which correlates with the second exit temperature TA2, after the finished rolled strip 145 has exited the second stand group 120.
  • the third temperature measuring device 80 sets a third information about the third surface temperature via the eighth data connection 200 of the interface 160 and via the interface 160 of the control device 150 ready.
  • the control device 150 can also take into account the information about the third surface temperature and control the volume flow of the cooling medium in such a way that the third surface temperature essentially corresponds to the third setpoint temperature TS3.
  • the second surface temperature can also be taken into account when regulating the volume flow, in order to ensure a uniformly high cooling rate in the second stand group 120 .
  • the Controller 150 regularly repeat the eleventh and twelfth method step 355, 360 in a loop at a predefined time interval.
  • a thirteenth method step 365 the finished rolled strip 145 is transported into the cooling section 55 in the cooled state.
  • the control device 150 deactivates or keeps the cooling section 55 in the deactivated state, so that when the finished rolled strip 145 runs through the cooling section 55, no further cooling medium is applied to the finished rolled strip 145 for further forced cooling of the finished rolled strip 145.
  • this is not necessary due to the high cooling capacity of the second stand group 120, and on the other hand, the convective cooling as it passes through the cooling section 55 is sufficient for further cooling of the finished rolled strip 145 from the second outlet temperature TA2 to a third outlet temperature TA3, which is below the second outlet temperature TA2.
  • the cooling medium remaining on the finished strip in particular cooling water, dries in the cooling section 55 . As a result, the finished rolled strip 145 cools down further in the cooling zone 55 .
  • control device 150 can also activate the cooling section 55 in order to forcibly cool the finished rolled strip 145 from the second exit temperature TA2 to the third exit temperature TA3.
  • a fourteenth method step 370 the finished rolled strip 145 , which has been further cooled in the cooling section 55 , is guided through the third separating device 35 to the coiler device 60 .
  • the finish-rolled, dried and cooled finish-rolled strip 145 is wound up into a coil in the coiling device 60 .
  • the control device 150 can activate the third separating device 35 so that the finished rolled strip 145 continuously conveyed from the cooling section 55 is separated from the coil and the coil can be removed.
  • the other finished rolled strip 145 transported through the cooling section 55 can be wound onto a new coil.
  • the compound casting-rolling system 10 described above and the method described in FIG. 2 have the advantage that the chemical composition, for example a chemical composition for an X60 steel, meets the mechanical conditions for an X70 to X120 micro-alloyed steel can become.
  • the micro-alloyed steel is particularly suitable as micro-alloyed pipe steel for the production of pipes, pipelines or pressure tanks. Particularly good material properties can be achieved by the cooling immediately following the first stand group 115 by means of the second finishing rolling mills 130 converted to stand coolers 135 and the intermediate coolers 140 can be ensured for the micro-alloyed steel. This makes the micro-alloyed steel particularly tough and strong.
  • the combined casting and rolling system 10 has a particularly precise temperature control.
  • the combined casting and rolling plant can be used if no micro-alloyed steel, in particular no micro-alloyed pipe steel, is to be produced 10 are operated conventionally, with the stand coolers 135 being converted back into second finishing rolling stands 130 in conventional operation. Furthermore, in conventional operation, the intercoolers 140 are deactivated and the cooling section 55 is activated.
  • the finished rolled strip 145 is then rolled by all five finishing rolling stands 125, 130 and the cooling of the finished rolled strip 145 essentially takes place in the cooling line 55 instead in the second stand group 120 to the second exit temperature TA2.
  • the second graph 405 (cf. FIG. 4) clearly shows how the finished rolled strip 145 slowly cools down from the first exit temperature TA1 to the second exit temperature TA2.
  • the first outlet temperature TA1 is approximately 800° C. to 950° C.
  • the finished rolled strip 145 is only cooled down in the cooling section 55 and a core temperature then drops rapidly there. Due to the fact that the finished rolled strip 145 cools slowly by about 50° C. to 100° C. over a period of about 15 to 50 seconds, the microalloyed steel that can be produced using the method described in FIG. 2 cannot be produced. In order to produce a desired micro-alloyed steel with these properties, additional alloying additives are necessary during conventional operation of the combined casting and rolling plant 10 shown in FIG.
  • the first graph 400 which represents the temperature profile of the method shown in FIG. 2, clearly shows how quickly the core of the finished rolled strip 145 is cooled from the first exit temperature TA1 to the second exit temperature TA2.
  • a higher-alloy steel for example an X70 to X120 steel
  • a chemical alloy which corresponds to an X60 steel
  • FIG. 7 shows a schematic ZTU diagram for an X60 steel melt.
  • the third setpoint temperature TS3 is specified as a function of a desired microalloyed steel to be produced.
  • the third setpoint temperature TS3 is selected at least lower than a ferrite-pearlite transformation temperature An, preferably lower than a bainite start temperature, in particular lower than a martensite start temperature Ms.
  • the finished rolled strip 145 in the second stand group 120 can be cooled in the twelfth method step 360.
  • the control device 150 controls the volume flow of the cooling medium fed to the finished rolled strip 145 and thus the cooling rate. If the third setpoint temperature TS3 is selected to be particularly low, the control device 150 controls the second stand group 120 in such a way that it cools the finished rolled strip 145 with a particularly large quantity of cooling medium. This has the advantage that a micro-alloyed steel with the mechanical properties of an X120 steel can be produced, for example by means of the chemical composition specified above, which essentially corresponds to an X60 steel, for example.
  • the third setpoint temperature TS3 is set above a martensite start temperature M s , a micro-alloyed steel with the mechanical properties of an X80 steel can be produced using the X60 steel melt 95 mentioned above.
  • the third setpoint temperature TS3 is set higher than just described, micro-alloyed steel with the mechanical properties of an X70 steel can be produced with the X60 steel melt.
  • the X70 and X80 micro-alloyed steels each have a predominantly bainitic B phase fraction, while the X120 micro-alloyed steel essentially has a martensite M phase fraction of 25-65%.
  • a typical X60 or X70 micro-alloyed steel with a pearlitic phase fraction P of 5-50 volume percent can be produced in a simple manner using the method described in FIG.
  • the microalloyed steel can have at least one of the following precipitates: Ti(C,N), Nb(C,N) V(C,N) TiC, TiN, Ti(C,N), (Nb,Ti)C, (Nb ,Ti)N, (Nb,Ti)(C,N), NbC, NbN, VC, VN, V(C,N), (Nb,Ti,V)(C,N), (Nb,V)C , (Ti,V)C, (Nb,V)(C,N), (Ti,V)(C,N), (Nb,V)N, (Ti,V)N, (Nb,Ti,V )C, (Nb,Ti,V)N.
  • a precipitation density of the precipitation(s) is 10 20 to 10 23 1/m 3 .
  • the precipitate has an average size of 1 nm to 20 nm.
  • the average size of the precipitates should be determined in a sample oriented at normal angles to the direction of conveyance. Transmission electron microscopy (TEM), for example, can be used to determine the average size and/or the composition of the excretion.
  • TEM Transmission electron microscopy
  • the size of the precipitates is preferably determined perpendicularly to a cross section of the finished rolled strip. It is of particular advantage if, for example, in a transverse direction perpendicular to the conveying direction of the finished rolled strip, the precipitation size of the precipitations is determined in several non-overlapping image sections in the cross section. It is also advantageous if the determination is made in the area of a strip center (based on a thickness and a width of the finished rolled strip).
  • FIG. 8 shows a schematic representation of a combined casting and rolling system 10 according to a second embodiment.
  • the combined casting and rolling facility 10 is essentially identical in design to the combined casting and rolling facility 10 shown in FIG. In the following, only the differences between the compound casting/rolling system 10 shown in FIG. 8 and the first embodiment of the compound casting/rolling system 10 shown in FIG. 1 will be discussed.
  • FIG. 8 has the advantage over FIG. 1 that in the conveying direction only the last second finishing rolling stand 130 has to be converted into the stand cooler 135 in preparation for the combined casting and rolling system 10 in order to use the method described in FIG to perform.
  • the effort involved in converting a conventional compound casting/rolling system 10 is kept particularly low.
  • This configuration is particularly suitable when only small amounts of the micro-alloyed steel are to be produced as part of an ESP process. Due to the fact that only one of the two second finishing rolling stands 130 is converted to the stand cooler 135, a conversion time back to the conventional structure, ie with five first and second finishing rolling stands 125, 130 that can be rolled, is particularly short.
  • micro-alloyed steel 8 has the advantage that a mechanically higher-quality micro-alloyed steel, for example X70 steel, can be produced cost-effectively using short conversion times, for example on the basis of a chemical composition of a micro-alloyed steel for an X60 steel .

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Metal Rolling (AREA)

Abstract

L'invention concerne un procédé de production d'un acier micro-allié, un acier micro-allié et une installation combinée de coulée/laminage. L'installation combinée de coulée/laminage (10) présente une machine de coulée continue (15) pourvue d'un moule (90) ; un train de prélaminage à une ou plusieurs cages (20) ; et un train de laminage de finition (50) comprenant un premier groupe de cages (115) présentant au moins une première cage de laminage de finition (125) et un deuxième groupe de cages (120) présentant au moins un refroidisseur de cage (135). Un métal fondu (95) est coulé dans le moule (90) pour former une brame mince partiellement solidifiée (100), la brame mince partiellement solidifiée (100) étant supportée, déviée et refroidie et la brame mince (100) étant introduite dans le train de prélaminage (20) dans un état sensiblement complètement solidifié. Le train de prélaminage (20) lamine la brame mince (100) en une bande prélaminée (110) et le premier groupe de cages (115) effectue un laminage de finition sur la bande prélaminée (110) pour obtenir une bande laminée finie (145). La bande laminée finie (145) est ensuite introduite dans le deuxième groupe de cages (120) immédiatement après le procédé de laminage de finition et la bande laminée finie (145) est soumise à un refroidissement forcé dans le deuxième groupe de cages (120) tout en maintenant l'épaisseur de la bande laminée finie (145) de telle sorte que la vitesse de refroidissement du noyau de la bande laminée finie (145) dans le deuxième groupe de cages (120) est supérieure à 20 °C/s et inférieure à 200 °C/s.
EP22730486.2A 2021-06-09 2022-05-25 Procédé de fabrication d'un acier micro-allié, acier micro-allié produit à l'aide du procédé et installation combinée de coulée/laminage Pending EP4351812A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP21178473.1A EP4101552A1 (fr) 2021-06-09 2021-06-09 Procédé de fabrication d'acier micro-allié, acier micro-allié fabriqué selon le procédé et installation combinée de coulée et de laminage
PCT/EP2022/064188 WO2022258376A1 (fr) 2021-06-09 2022-05-25 Procédé de fabrication d'un acier micro-allié, acier micro-allié produit à l'aide du procédé et installation combinée de coulée/laminage

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EP4351812A1 true EP4351812A1 (fr) 2024-04-17

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EP21178473.1A Withdrawn EP4101552A1 (fr) 2021-06-09 2021-06-09 Procédé de fabrication d'acier micro-allié, acier micro-allié fabriqué selon le procédé et installation combinée de coulée et de laminage
EP22730486.2A Pending EP4351812A1 (fr) 2021-06-09 2022-05-25 Procédé de fabrication d'un acier micro-allié, acier micro-allié produit à l'aide du procédé et installation combinée de coulée/laminage

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EP21178473.1A Withdrawn EP4101552A1 (fr) 2021-06-09 2021-06-09 Procédé de fabrication d'acier micro-allié, acier micro-allié fabriqué selon le procédé et installation combinée de coulée et de laminage

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US (1) US20240269734A1 (fr)
EP (2) EP4101552A1 (fr)
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WO (1) WO2022258376A1 (fr)

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EP4438746A1 (fr) 2023-03-27 2024-10-02 Primetals Technologies Austria GmbH Procédé de fabrication directe d'une bande d'acier trip dans une installation composite de coulée-laminage et bande d'acier trip ainsi fabriquée
EP4474488A1 (fr) * 2023-06-09 2024-12-11 Semplice S.p.A. Ligne et procédé de traitement de fils et/ou de torons métalliques

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DE19913498C1 (de) * 1999-03-25 2000-10-12 Thyssenkrupp Stahl Ag Verfahren zum Herstellen eines Warmbandes und Warmbandlinie zur Durchführung des Verfahrens
DE10131369A1 (de) * 2001-06-28 2003-01-09 Sms Demag Ag Verfahren und Vorrichtung zum Kühlen und Schmieren von Walzen eines Walzgerüstes
JP2005296973A (ja) * 2004-04-07 2005-10-27 Sumitomo Metal Ind Ltd 熱延鋼板の製造方法とその装置
US10071416B2 (en) * 2005-10-20 2018-09-11 Nucor Corporation High strength thin cast strip product and method for making the same
CN102051527B (zh) * 2010-11-16 2012-06-20 天津钢管集团股份有限公司 高强度高韧性x90厚壁无缝管线钢管及其制造方法
AT512399B1 (de) 2012-09-10 2013-08-15 Siemens Vai Metals Tech Gmbh Verfahren zum Herstellen eines mikrolegierten Röhrenstahls in einer Gieß-Walz-Verbundanlage und mikrolegierter Röhrenstahl
DE102013107010A1 (de) * 2013-07-03 2015-01-22 Thyssenkrupp Steel Europe Ag Anlage und Verfahren zum Warmwalzen von Stahlband
EP3434383A1 (fr) 2017-07-24 2019-01-30 Primetals Technologies Austria GmbH Dispositif de refroidissement de cage permettant le refroidissement d'un feuillard en acier dans une cage de laminoir
EP3670011B1 (fr) 2018-12-21 2022-09-28 Primetals Technologies Austria GmbH Refroidissement de la bande métallique dans une cage de laminoir

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US20240269734A1 (en) 2024-08-15
WO2022258376A1 (fr) 2022-12-15
EP4101552A1 (fr) 2022-12-14
CN117545564A (zh) 2024-02-09

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