Classifications

• • 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
  • C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
  • C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
• • 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
  • C21D1/56—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
  • C21D1/60—Aqueous agents
• • 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
  • C21D1/63—Quenching devices for bath 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
  • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
  • C21D9/0075—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rods of limited length
• • 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
  • C21D9/5732—Continuous furnaces for strip or wire with cooling of wires; of rods
• • 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
• • 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
  • B21B1/16—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 wire rods, bars, merchant bars, rounds wire or material of like small cross-section
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B2201/00—Special rolling modes
  • B21B2201/06—Thermomechanical 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
  • C21D2211/00—Microstructure comprising significant phases
  • C21D2211/008—Martensite
• • 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

Definitions

• the present invention relates to a plant for the thermomechanical rolling of long steel semi-finished products, a method for producing wire and/or rod-shaped steels, preferably structural steels, from the long steel semi-finished products, in particular with a yield point of at least 300 MPa, preferably with a yield point of at least 400 MPa, and a steel product in the form of wire and/or rod, which is preferably obtainable by the process according to the invention.
• Quality steels have been developed are increasingly used for the production of reinforcing steel, since with these, in addition to a significant improvement in the essential properties of structural steel, in particular the ductility properties, a reduction in alloying and operating costs can be achieved at the same time.
• the ductility properties are of crucial importance here, especially in regions prone to earthquakes, in order to minimize the risk of structural failure.
• structural steel In order to be approved as a structural building material, structural steel must meet a number of specific technological requirements. These include, above all, specifications for yield strength and tensile strength, ductility, elongation at break A, reduction in area at fracture Z, notched bar impact work K, weldability, which is mainly given as a carbon equivalent (Ceq), and the
• thermomechanical processes known from the prior art for the production of wire and/or rod-shaped structural steels purely ferritic-pearlitic microstructures can be achieved over the entire cross-section, so that structural steel products produced in this way have the required ductility properties in addition to high strength values. Since the entire cooling process is unstable in relation to the respective target temperatures, the process management often leads to the sudden formation of undetected, martensitic microstructures in the edge areas of the wire and/or rod-shaped structural steels, which have a negative effect on the required ductility properties .
• the present invention is therefore based on the object of providing a plant for the thermomechanical rolling of long steel semi-finished products and a method for the production of wire and/or rod-shaped steels, in particular structural steels, with which wire and/or rod-shaped steels, in particular structural steels, can be produced with consistent quality in terms of their microstructure and mechanical properties.
• the object is achieved by a system having the features of patent claim 1 and a method having the features of patent claim 8 .
• the plant according to the invention for the thermomechanical rolling of long steel semi-finished products into a wire and/or bar-shaped steel comprises a first rolling device; one downstream of the first
• thermomechanical sizing block arranged downstream of the second rolling means; a second cooling device disposed between the second rolling device and the first thermomechanical sizing block; a cooling bed, ring laying and/or coil winding device arranged downstream of the first thermomechanical sizing block in the transport direction; a third cooling device arranged between the first thermomechanical sizing block and the cooling bed, ring laying and/or coil winding device; as well as a microstructure sensor device arranged between the first thermomechanical sizing block and the cooling bed, ring laying and/or coil winding device, via which a martensitic microstructure, in particular a martensite proportion in area percentage (A.- %), in the thermomechanically rolled long steel semi-finished product or in the wire and/or bar-shaped steel can be determined directly during the ongoing process.
• A.- % martensitic microstructure
• the invention relates to a method for producing wire and/or bar-shaped steels from long steel semi-finished products, in particular with a yield point of at least 300 MPa, preferably with a yield point of at least 400 MPa, even more preferably with a yield point of at least 500 MPa, and most preferably having a yield strength of at least 600
• MPa MPa, the first being optionally heated to a temperature of at least 900 °C, preferably to a temperature of at least 950 °C
• Long steel semi-finished product is pre-rolled in a first rolling device and optionally cooled in a subsequent first cooling device; it is then temper-rolled in a second rolling device arranged downstream of the first rolling device in the direction of transport and cooled to a temperature of at least 850° C.
• thermomechanical sizing block arranged downstream of the second cooling device in the direction of transport to form the wire and/or bar-shaped steel, which is then heated to a temperature in the range from 400 °C to 850 °C in a third cooling device that is connected to the first thermomechanical sizing block is cooled; is then fed to a cooling bed, ring-laying and/or coil-winding device arranged downstream of the third cooling device in the transport direction, with a microstructure sensor device arranged in a section between the first thermomechanical sizing block and the cooling-bed, ring-laying and/or coil-winding device being used to detect any existing martensitic structure in the thermomechanically rolled long steel semi-finished product or in the wire and/or bar-shaped steel is determined directly in the ongoing process.
• the manufacturing process can be made significantly more effective, since the online identification of the Martensite structure can be directly influenced on the respective process parameters, for example to the effect that the temperature in the respective cooling devices, the rolling temperature and / or the decreases in the respective rolling units can be adjusted.
• wire-shaped and/or bar-shaped steels, in particular structural steels are obtained which have an almost constant, martensite-free quality with regard to their microstructure.
• the temperatures given here represent the average temperatures over the cross-section of the rolling stock and therefore cannot be equated with surface temperatures.
• the term “long steel semi-finished products” is understood to mean steel semi-finished products which are suitable for producing the wire-shaped and/or bar-shaped steels or steel products, in particular structural steels, according to the invention. Such semi-finished long steel products are also referred to as billets and usually have a square or rectangular cross-section.
• wire and/or rod-shaped steels or steel products is understood to mean steel products, in particular structural steels. These preferably have a round cross-section with a ribbed and/or smooth surface.
• Wire-shaped steel products within the meaning of the present invention can have a diameter in the range from 4.5 to 29 mm, preferably a diameter in the range from 5.5 to 16 mm, and at the end of the
• the wire-shaped steel product is formed into wire coils of a desired size via the ring laying device or the coiling device, then fanned out on a roller conveyor for homogeneous cooling and then collected as a coil in a coil forming chamber.
• Bar-shaped steel products can have a diameter in the range of 8.0 to 60.0 mm or 6.0 to 50.0 mm. If the long steel semi-finished products are to be processed into bar steel with finished lengths of up to 12 m, the bar-shaped steel products have a diameter in the range from 8.0 to 60.0 mm and are fed to a cooling bed at the end of the production line. If the long steel semi-finished products are to be processed into bar steel that is wound into a coil, the bar-shaped steel products have a diameter in the range from 6.0 to 50 mm, preferably a diameter in the range from 6.0 to 32.0 mm, and then become one at the end of the production line Coil winding device supplied.
• the first rolling device in which the long steel semi-finished product that has previously been heated to a temperature of at least 900° C., preferably to a temperature of at least 950° C., is pre-rolled, can be formed from a large number of roll stands without stands.
• the first rolling device comprises at least six, more preferably at least eight, even more preferably at least ten, and most preferably twelve of these standless rolling stands.
• a first cooling device can be arranged downstream of the first rolling device in the direction of transport if the temperature of the pre-rolled long steel semi-finished product has to be regulated.
• the first cooling device comprises one or two water tanks which are arranged at a distance from one another in a first section between the first and the second rolling device.
• the pre-rolled semi-finished long steel products are then re-rolled in the second rolling device.
• the second rolling facility advantageously comprises at least two, more preferably at least four, and most preferably six standless rolling stands.
• the first and/or the second rolling device can comprise hydraulically adjustable roll stands instead of the roll stands without stands.
• the long steel semi-finished product finish-rolled in the second rolling device can be separated into two individual strands by forming in the last roll stand in the transport direction, which can be finish-rolled in the further process in thermomechanical sizing blocks arranged parallel to one another to form the wire and/or rod-shaped steel products .
• the second cooling device is arranged in a second route section behind the second rolling device in the direction of transport.
• the second cooling means advantageously comprises at least two, more preferably at least three or four, water boxes spaced apart in the second line section to achieve a temperature reduction in the rolled stock prior to the thermomechanical rolling step.
• the first and the second section are preferably selected in such a way that the rolling stock is given enough time for a sufficient temperature equalization over the cross section.
• the temperature in the rolling stock is equalized by conduction from the core to the surface.
• a temperature gradient of at most 100 °C, more preferably a temperature gradient of at most 80 °C, even more preferably a temperature gradient of at most 60 °C, and most preferably, a temperature gradient of at most 50° C. is set.
• the homogenization of the cross-section temperatures can be controlled indirectly between the respective stations by measuring the surface temperatures of the rolled long steel semi-finished product.
• corresponding process models can also be used.
• the first section between the first and the second rolling device therefore advantageously has a length of 40 to 80 m, more preferably a length of 45 to 60 m.
• the second section between the second rolling device and the first thermomechanical rolling block advantageously has a length of 100 to 140 m, more preferably a length of 115 to 130 m.
• the rolled long steel semi-finished product which has been cooled down to a temperature of at least 850 °C in the second cooling device, is then fed to the first thermomechanical sizing block, in which it is finish-rolled to the desired or specified final diameter.
• the rolled long steel semi-finished product is heated to the first thermomechanical sizing block at a temperature in the range of 700 °C, preferably at a temperature of at least 730 °C, more preferably at a temperature of at least 750 °C, even more preferably at a temperature of at least 760°C, and most preferably at a temperature of at least 770°C.
• the temperature of the rolled long steel semi-finished products must not be too high, otherwise the lowest possible temperature gradient between the surface and core temperatures required for the metallurgical recrystallization processes and the associated grain refinement effects cannot be set.
• the temperature at which the rolled long steel semi-finished product is fed to the first thermomechanical sizing block is limited to 850°C, preferably to 840°C, more preferably to 820°C, and most preferably to 800°C. Provision is very particularly preferably made for the rolled long steel semi-finished product to be fed to the first thermomechanical sizing block at a temperature of 780°C.
• the highest deformation or the highest reduction which can preferably be 30 to 80%, takes place.
• the thermomechanical sizing block can have one, preferably two, more preferably four, even more preferably six, and most preferably eight stands.
• the system can comprise a second thermomechanical sizing block between the first thermomechanical sizing block and the third cooling device, which also has one, preferably two, more preferably four, even more preferably six, and most preferably eight stands can be trained.
• an intermediate cooling device is provided between the two thermomechanical sizing blocks, which comprises one or two water tanks spaced apart from one another.
• the first thermomechanical sizing block can have four stands and the second thermomechanical sizing block can have two stands.
• the first thermomechanical sizing block can, for example, have four stands and the second thermomechanical sizing block can likewise have four stands. Any other combination is possible and conceivable with regard to the division of the aforementioned stands between the two thermomechanical sizing blocks.
• thermomechanical sizing block designed in a basic design could also be divided into six single-stand thermomechanical sizing blocks, with within the entire cascade of, for example, six single-stand thermomechanical sizing blocks between two of these six one-stand thermomechanical sizing blocks each have to be provided with an intermediate cooling device with at least one water box.
• the thermomechanical sizing blocks are known in principle and are sold by the applicant under the brand name MEERdrive®.
• the third cooling device is then arranged in a third line section, in which the long steel semi-finished products finish-rolled into wire and/or bar-shaped steels are cooled in order to stop further grain growth.
• the third cooling device comprises at least one, preferably at least two, more preferably at least three, even more preferably at least four, and most preferably at least five water tanks, via which the wire and/or rod-shaped steels are cooled in order to ensure temperature equalization , and on the other hand to prevent the formation of hardened microstructures in the form of martensite or bainite.
• the third cooling device particularly advantageously comprises two to twelve water tanks, more preferably four to ten water tanks.
• the cooling capacity of the respective water boxes of each cooling device can be specifically adjusted based on the volume flow of the cooling water, the number of active cooling tubes per water box, the cooling tube diameter and/or the cooling water pressure and, if necessary, the cooling water temperature.
• the specifications can typically be predetermined using specific process models and adjusted using online control.
• An example channel box may have a channel box length of 6500mm and include six cooling tubes each 750mm long. Such a water box then typically has a maximum cooling water quantity of 230 m 3 /h and a controllable cooling water pressure range from 1.5 to 6.0 bar.
• the third section which extends between the first or second thermomechanical sizing block and the cooling bed, ring laying or coil winding device, is preferably selected in such a way that the rolling stock has enough time for adequate temperature equalization across the cross section.
• the third section therefore advantageously has a transport length of 110 to 150 m, more preferably a transport length of 110 to 130 m.
• cooling which starts as quickly as possible immediately after the last pass, i.e.
• thermomechanical sizing block for controlling the recrystallization processes and a high degree of fineness, preferably with an average grain diameter of less than 12.0 ⁇ m, even more preferably with an average grain diameter of less than 10.0 ⁇ m is decisive.
• the wire and / or rod-shaped steels which have a temperature in the range of 700 ° C to 1100 ° C after the last pass, after a maximum of 300 ms, preferably after a maximum of 200 ms, even more preferably after a maximum 100 ms, more preferably after a maximum of 90 ms, and most preferably after a maximum of 80 ms, to the third cooling device, in particular to the first water tank of the third cooling device.
• the wire and/or rod-shaped steels are cooled to such an extent that a cooling bed inlet temperature, an inlet temperature in the ring laying device and/or an inlet temperature in the coil winding device in the range of 400 °C to 850 °C is achieved.
• a particularly advantageous cooling bed inlet temperature is 550°C to 750°C, more preferably 600°C to 650°C.
• a particularly advantageous entry temperature into the coil winding device is 450°C to 550°C.
• a particularly advantageous inlet temperature in the ring-laying device is 600°C to 750°C.
• the structure sensor device according to the invention which is arranged in the third section between the first or second thermomechanical sizing block and the cooling bed, ring laying or coil winding device, can advantageously be installed in the transport direction directly in front of the cooling bed, ring laying or coil winding device, directly in front of one in the transport direction separating device arranged in front of the cooling bed, ring laying or coil winding device, and/or in the direction of transport, possibly directly behind the third cooling device, in particular behind the last water box.
• An arrangement between two water tanks of the plurality of water tanks in the third cooling device is also possible.
• the system comprises a structure sensor device according to the invention behind each of the plurality of water tanks that are arranged within the third cooling device in the third section.
• each of the plurality of water tanks can be adjusted individually and the formation of martensitic structures in the specific water tanks can be assigned.
• the martensitic structure, in particular a proportion of martensite in A%, in the wire-shaped and/or rod-shaped steels can be identified online in the ongoing process via the structure sensor device.
• all techniques known to the person skilled in the art at the time of filing can be used as measurement methods.
• the microstructure sensor device for identifying the undesired martensite has an ultrasonic measuring device, an X-ray measuring device, a radar beam measuring device and/or an electromagnetic measuring device.
• the microstructure sensor device can advantageously be coupled to a control and/or regulation device, via which active interventions in the respective process steps can be undertaken, possibly with the aid of appropriate algorithms, in order to set the desired microstructure.
• the present invention also relates to a steel product in wire and/or rod form, preferably produced by the method according to the invention, in particular with a yield point of at least 300 MPa, more preferably with a yield point of at least 400 MPa, even more preferably with a yield point of at least 500 MPa, and most preferably with a yield strength of at least 600 MPa, having a martensite content of at most 15.0 A%, preferably one
• a maximum martensite content of 10.0 A% more preferably a maximum martensite content of 8.0 A%, even more preferably a maximum martensite content of 6.0 A%, and most preferably a maximum martensite content of 5.0 A%.
• the wire and/or rod-shaped steel in particular structural steel, preferably has the following chemical composition in % by weight:
• Nitrogen maximum 0.012, and the remainder iron, possibly other accompanying elements, and unavoidable impurities.
• the wire and/or rod-shaped steel can preferably include the following elements individually and/or in combination as additional accompanying elements (in % by weight):
• Chromium 0.40 maximum
• Molybdenum 0.20 maximum
• Nickel 0.90 maximum
• Copper 0.65 to 1.0
• Lead 0.25 maximum
• Tin maximum 0.07. Provision is particularly preferably made for the wire and/or bar-shaped steel, in particular structural steel, to have a carbon equivalent (Ceq) of ⁇ 0.60, more preferably a carbon equivalent (Ceq) of ⁇ 0.50.
• FIG. 2 shows a temperature profile of a first exemplary embodiment of the method according to the invention
• FIG. 3 shows a temperature profile of a second exemplary embodiment of the method according to the invention
• FIG. 4 shows a temperature profile of a third exemplary embodiment of the method according to the invention.
• FIG. 1 shows an embodiment variant of the system 1 according to the invention for thermomechanical rolling of long steel semi-finished products 2 in a schematic block diagram.
• Such long steel semi-finished products 2, which are thermomechanically rolled in plant 1 to form the wire and/or bar-shaped steels 3, can have a quadrilateral (square) cross section with the dimensions of 165 ⁇ 165 mm.
• the correspondingly finish-rolled wire and/or bar-shaped steels 3 can have a diameter in the range from 4.5 to 29 mm (wire-shaped steel) or a diameter in the range from 8.0 to 60.0 mm or 6.0 to 50.0 (bar-shaped steel).
• the long steel semi-finished products 2 are first fed to a reheating furnace 4 in which the long steel semi-finished products 2 to be rolled are heated to a temperature of 900° C. to 1000° C.
• the then heated long steel semi-finished products 2 are fed to a first rolling device 5, in which they are pre-rolled in a cascade of twelve standless rolling stands (not shown).
• a reduction of 20 to 40% per pass is achieved in the respective roll stand.
• the average temperature of the rolling stock in the first rolling device 5 is 900°C to 1100°C.
• a first cooling device 6 with one or two water tanks can be arranged downstream of the first rolling device 5 in the transport direction in order to be able to readjust the temperature of the pre-rolled long steel semi-finished product 2 before it is fed to a second rolling device 7 .
• the first cooling device 6 is arranged in a first section 8 between the first and the second rolling device 5, 7, which is selected such that the rolling stock has enough time for a sufficient temperature equalization between the two rolling processes.
• the first section 8 can have a length of 45 to 60 m.
• the pre-rolled semi-finished long steel products 2 are then re-rolled in a cascade of six stand-less roll stands (not shown), with a reduction of 20 to 30% per pass in the respective roll stand being achieved.
• the average temperature of the rolling stock in the second rolling device 7 is 800°C to 1000°C.
• a second cooling device 9 is arranged in a second section 10, which in the present case comprises three spaced-apart water tanks (not shown) in order to reduce the temperature of the 800 °C to 1000 °C hot rolling stock before the subsequent step of thermomechanical to achieve rolling.
• the second section 10 is also selected in such a way that the rolling stock is given enough time for a sufficient temperature equalization over its cross section in addition to the temperature reduction.
• the second route section can therefore have a length of 115 m to 130 m.
• the first thermomechanical sizing block 11 can be designed with six stands in one embodiment variant, with a decrease of approximately 22 to 27% being achievable per pass in the individual stands.
• the first thermomechanical sizing block 11/11.1 can be supplemented by a second thermomechanical sizing block 11.2, which can also have a multi-stand design.
• an intermediate cooling device 13 with at least one water tank (not shown) is provided in an intermediate section 12 formed between the two thermomechanical sizing blocks 11.1, 11.2.
• This intermediate section 12 also has a specific distance of 30 m, for example, in order to allow the rolling stock sufficient time for adequate temperature equalization over its cross section.
• the third cooling device 14 is then arranged in a third section 15 in the transport direction behind the first or the second thermomechanical sizing block 11.1, 11.2.
• the long steel semi-finished products 2 which have been finish-rolled into wire and/or bar-shaped steels 3 and have a temperature of 700 °C to 1050 °C, are cooled by a cascade of four or five water tanks spaced one behind the other in order to prevent further grain growth and to To prevent the formation of hardened microstructures in the form of martensite or bainite.
• cooling that starts as quickly as possible immediately after the last stitch is required in order to be able to control the recrystallization processes and a high level
• the third section 15 is also chosen to be correspondingly long. This can have a length of 110 to 130 m, for example.
• the rod-shaped steels 3 are then fed to a cooling bed device 16 with a cooling bed inlet temperature of 550 °C to 750 °C, to a coil laying device 16 with an inlet temperature of 600 °C to 750 °C, or with a coil winding temperature of 450 °C to 550 °C C fed to a coil winding device 16 .
• the system 1 also includes a microstructure sensor device 17, which is arranged in the third section 15.
• the formation of a martensitic structure, in particular a proportion of martensite in A %, in the wire-shaped and/or rod-shaped steels 3 can be identified online in the ongoing process via the structure sensor device 17 .
• the microstructure sensor device 17 can include, for example, an ultrasonic measuring device, an X-ray measuring device, a radar beam measuring device and/or an electromagnetic measuring device.
• an ultrasonic measuring device for example, an ultrasonic measuring device, an X-ray measuring device, a radar beam measuring device and/or an electromagnetic measuring device.
• Structure sensor device 17 is shown in the third section 15 .
• it can be arranged in front of the third cooling device 14 in the direction of transport or directly in front of the cooling bed, ring laying or coil winding device 16 .
• FIGS. 2 to 4 show three different temperature profiles (average temperatures) 18, 19, 20 of three steel rods 3 with different diameters, which were produced according to an embodiment of the method according to the invention.
• billets of grade HRB 400 with a quadrilateral (square) cross-section with dimensions of 165 x 165 mm were produced in a plant 1, which had a reheating furnace 4, a first rolling device 5 with twelve standless roll stands (not shown), a first cooling device 6 with two water tanks, a second rolling device 7 with six uprights
• Rolling stands (not shown), a second cooling device 9 with three water boxes, a six-stand sizing block 11, a third
• Cooling device 14 with five water tanks and a cooling bed device 16, thermomechanically rolled into steel bars 3 with diameters of 8 mm (Fig. 2), 18 mm (Fig. 3) and 25 mm (Fig. 4).
• Reference List

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• 2021
  • 2021-05-28 DE DE102021205429.3A patent/DE102021205429A1/de active Pending
• 2022
  • 2022-03-29 CN CN202280038165.0A patent/CN117396616A/zh active Pending
  • 2022-03-29 KR KR1020237041004A patent/KR20240004700A/ko unknown
  • 2022-03-29 WO PCT/EP2022/058212 patent/WO2022248102A1/de active Application Filing
  • 2022-03-29 EP EP22718929.7A patent/EP4347905A1/de active Pending

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