Classifications

• • 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
  • 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
• • 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
  • B21B1/22—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 plates, strips, bands or sheets of indefinite length
  • B21B1/24—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 plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process
  • B21B1/26—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 plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process by hot-rolling, e.g. Steckel hot mill
• • 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
  • B21B1/22—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 plates, strips, bands or sheets of indefinite length
  • B21B1/30—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 plates, strips, bands or sheets of indefinite length in a non-continuous process
  • B21B1/32—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 plates, strips, bands or sheets of indefinite length in a non-continuous process in reversing single stand mills, e.g. with intermediate storage reels for accumulating work
  • B21B1/34—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 plates, strips, bands or sheets of indefinite length in a non-continuous process in reversing single stand mills, e.g. with intermediate storage reels for accumulating work by hot-rolling
• • 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
  • B21B1/466—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 non-continuous process, i.e. the cast being cut before rolling
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B2201/00—Special rolling modes
  • B21B2201/04—Ferritic rolling
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B2201/00—Special rolling modes
  • B21B2201/12—Isothermic rolling
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B2201/00—Special rolling modes
  • B21B2201/14—Soft reduction
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
  • B21B45/004—Heating the product
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
  • B21B45/02—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
  • B21B45/0203—Cooling
  • B21B45/0209—Cooling devices, e.g. using gaseous coolants
  • B21B45/0215—Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes
  • B21B45/0218—Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes for strips, sheets, or plates
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/4998—Combined manufacture including applying or shaping of fluent material
  • Y10T29/49988—Metal casting
  • Y10T29/49991—Combined with rolling

Definitions

• the invention relates to a method for producing steel strip with cold rolling properties according to the preamble of claim 1 and a system for performing this method
• a generic method is known from EP 0 541 574 B1, in which finished strip with cold rolling properties is produced directly in a hot rolling mill from a raw material produced by casting close to final dimensions. It provides that a thin slab strand with a maximum thickness of 100 mm is first produced in a continuous casting installation, with a rolling device being arranged directly behind the continuous casting mold. on which the casting strand is rolled to the solidification thickness with a liquid and solid core (casting rolls). The thin slab strand is then descaled and hot-rolled to a thickness of 10 - 30 mm at temperatures above 1100 ° C on a rolling device with, for example, three stands. The intermediate strip, which is hot-rolled in this way, is divided into partial lengths using band shears.
• the known method aims at the production of cold rolling strip with as little energy expenditure as possible.
• the hot rolling is carried out in part with the heat remaining from the continuous casting process.
• the disadvantage here is the need to provide inductive heating of the strip-shaped intermediate product for the second part of the hot rolling despite the use of the heat from the continuous casting
• the object of the invention is. to specify a method and a plant for its implementation, in which a separate reheating of the strip-shaped intermediate product and the energy and plant expenditure associated therewith are avoided.
• the properties of the material produced should be improved as far as possible in the direction of the cold rolling properties.
• the present invention only provides a single coherent hot rolling process, that is to say it dispenses with a second hot rolling process and the inductive intermediate heating required for this.
• the hot rolling takes place in a single pass, at the end of which there is accelerated cooling to a temperature in the range from 850 to 600 ° C.
• the finished steel strip is then produced by isothermal rolling in at least three pass passes, in each of which a thickness reduction of at least 35% takes place, and following this finishing rolling accelerated to a temperature of at most only 100 ⁇ C cooled.
• the finish rolling takes place at a comparatively significantly lower temperature (approx. 250 to 600 ° C.).
• ⁇ T 0 to 20 ° C.
• the method should expediently be operated in such a way that the heat input by means of a specially introduced deformation work ("speed up") is always above the heat loss to be expected due to radiation and the temperature control is ensured by means of targeted cooling between the rolling passes. If, in fact, the actual temperature of the steel strip has fallen below a critical value during the rolling process, it is hardly possible to achieve a return to the desired value by changing the rolling parameters.
• the intermediate vessel 11 allows the contained steel melt to flow in a continuous flow into a continuous casting mold 12 arranged underneath, which has liquid cooling (not shown) and leads to the formation of a casting strand consisting of a continuous shell and a liquid core.
• the hot casting strand arrives in a casting roller device arranged below the continuous casting mold 12, which further reduces the thickness of the casting strand with the partially liquid core.
• the thin slab strand 1 with a thickness of 30 to 100 mm, preferably 40 to 70 mm emerges from the casting roller device 13.
• the thickness reduction during casting rolling is at least 10%, preferably at least 30%.
• the strand then passes into a descaling device 19, which is preferably designed as a hydromechanical descaling device.
• the thin slab mill 1 has a temperature in the range of 1150 up to 900 ° C.
• the thin slab strand 1 is fed to a hot rolling device 15 directly downstream of the descaling device 19, in which the thickness of the thin slab strand 1 is reduced by at least 50% to form an intermediate belt of a maximum of 20 mm, preferably 10 to 20 mm, in thickness.
• a compensating furnace (not shown) directly in front of the hot rolling device 15, which holds the thin slab strand 1, which is expediently separated into partial lengths, at the desired hot rolling temperature.
• the hot rolling device 15 which expediently has two or three stands or else one Reversing rolling mill has, it is normally recommended to switch on a separating unit, for example in the form of a band shear 17, to divide the intermediate strip produced into the partial lengths already mentioned.
• the hot-rolled intermediate strip according to the invention accelerates cooled to a temperature in the range 850-600 ⁇ C.
• the respective expedient to either end Abkuhltemperatur ⁇ chtet on the chemical composition of the steel used and on the desired Gefugezusammen GmbH and after to be obtained mechanical properties in the finished strip.
• the cooling takes place in a first cooling device 18, which is connected directly to the band shears 17 in the diagram shown.
• a winding device 20 In many cases it is advisable, for reasons of space, to wind up the sections of the intermediate strip which are at the temperature desired for the subsequent finish rolling in a winding device 20 to form intermediate strip coiis and to keep them at the desired temperature in a compensating furnace 21.
• the intermediate strip for carrying out the subsequent finishing rolling is unwound again on an unwinding device 22 directly downstream of this compensating furnace 21.
• a Walzein ⁇ chtung 24 For the finishing rolling, which is carried out of the isothermal rolling in the temperature range from 600 to 850 C in ⁇ form, a Walzein ⁇ chtung 24 is provided which has at least three scaffolding.
• a rolling device with four or a maximum of five stands is recommended. An even larger number of finishing stands is generally not practical.
• the rolling stands are operated in such a way that the strip thickness is reduced by at least 25% per roll pass.
• the finished strip leaving the rolling mill has a maximum thickness of 2 mm, preferably a thickness of 0.5 to 1.5 mm.
• the actual temperature of the steel strip in the rolling device 24 is monitored by temperature sensors (not shown).
• the steel strip emerging from the rolling device 24 is immediately accelerated in a second cooling device 25 to a temperature of at most 100 ° C.
• the accelerated cooling expediently takes place at a cooling rate in the range from 10 to 25 ° C./s.
• the finished strip can be passed through a liquid cooling bath.
• spray cooling devices with the smallest possible roller spacing of less than 250 mm can also be used in the course of the roller table in a manner known per se.
• the finished strip produced in this way should expediently be wound up in the form of coils for removal.
• a corresponding winding device 26 is provided in the system diagram.
• intermediate band coils provided between the hot rolling device 15 and the rolling device 24 has the advantage that, on the one hand, an intermediate material buffer is created which allows the rolling devices to operate less prone to malfunction, and, on the other hand, the compensation furnace 21 required for maintaining the temperature of such a buffer material only has a comparatively small area claimed.
• the casting strand When it emerged from the continuous casting mold, the casting strand still had a liquid core with a format of 80 mm thick and 1300 mm wide. The mean temperature of this cast strand was about 1310 at the mold outlet ⁇ C. In this state, the Dünnbrammengibilitiestrang was introduced into a casting roll and reduced in thickness by 25%, so that a solidification thickness of 60 mm yielded. After descaling with the help of a pressurized water jet, the thin slab strand was reduced in thickness on a three-stand hot rolling mill by approx. 66%, so that an intermediate strip with a thickness of 20 mm was created.
• the temperature at the entry into the hot rolling mill was at 1130 C and ⁇ at the outlet at 938 ° C.
• this intermediate belt was divided into sections and cooled to a temperature of about 700 ° C. accelerated.
• a compensating oven which was also operated at 700 C ⁇
• the finishing train generated from the partial lengths were fed. This had a total of five stands, which were operated with a total thickness reduction of 95%.
• the intermediate belt fed to the first roll stand at 650 ⁇ C had a somewhat elevated temperature of 658 ⁇ C when it emerged from this stand, which was reduced to approx. 650 ⁇ C again by a spray cooling device arranged in front of the second roll stand.
• the outlet temperature of the second roll stand of 664 C ⁇ through a further spray cooling device on an inlet temperature for the third rolling stand 650 C ⁇ was reduced prior to the third roll stand.
• the finished strip produced in this way with 1 was 0 mm in thickness in a water cooling at a cooling rate of 21 ⁇ C / s cooled down to about 90 ° C and subsequently wound into finished coils.
• the finished strip produced in this way showed excellent mechanical and technological properties that were comparable to that of a cold strip.
• the production route according to the invention leads to a particularly fine-grained microstructure, which is clearly less expensive than the result according to the method known from EP 0 541 574 B1.
• reheating to 1100 ° C. before the second hot rolling leads to a significant grain coarsening, which is excluded in the method according to the invention because of the selected temperature range from 850 to 600 ° C.
• Another difference with regard to grain size formation comes from the different finish rolling.
• further dynamic grain refinement with a simultaneous increase in strength and toughness takes place during isothermal rolling, which takes place at temperatures lying at the recrystallization threshold, at the prescribed overall degree of deformation of well over 90%.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Physics & Mathematics (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Metal Rolling (AREA)
• Heat Treatment Of Sheet Steel (AREA)
• Heat Treatment Of Steel (AREA)
• Continuous Casting (AREA)

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Publications (2)

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• 1995
  • 1995-09-21 JP JP51357596A patent/JP3807628B2/ja not_active Expired - Fee Related
  • 1995-09-21 EP EP95932632A patent/EP0804300B1/fr not_active Expired - Lifetime
  • 1995-09-21 AU AU35613/95A patent/AU686014B2/en not_active Ceased
  • 1995-09-21 US US08/817,784 patent/US5832985A/en not_active Expired - Lifetime
  • 1995-09-21 WO PCT/DE1995/001347 patent/WO1996012573A1/fr active IP Right Grant
  • 1995-09-21 AT AT95932632T patent/ATE179640T1/de active
  • 1995-09-21 CN CN95195695A patent/CN1062196C/zh not_active Expired - Fee Related
  • 1995-09-21 CA CA002202616A patent/CA2202616C/fr not_active Expired - Fee Related

Non-Patent Citations (1)

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