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
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
• • 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
  • 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
• • 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
• • 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
• • 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
• • 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
• • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
  • B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product

Definitions

• the invention relates to a method for producing a microalloyed steel, in particular a tubular steel, wherein a cast slab undergoes a plant, in the conveying direction of the slab in this order, a casting machine, a first furnace, at least one roughing stand, a second furnace, at least one finishing stand and having a cooling section. Furthermore, the invention relates to a plant for producing a microalloyed steel.
• Thermomechanical rolling is an established process. Microalloyed steels have become increasingly important in recent times. Tubular steels (according to API Specification 5L) are one of the most important subgroups within the microalloyed steels. The demand for these steels is steadily increasing. The majority of tubular steels are produced on plate rolling mills. However, tube steels can be produced, in particular with not too great final thicknesses and final widths, as well as on hot strip mills, so-called CSP plants and other hot rolling facilities. Particular attention is paid to the production of microalloyed steels in general and of tube steels in particular to the temperature profile as a function of time (or as a function of the location within the manufacturing plant). This process, in combination with the decrease distribution, significantly influences the development of the microstructure and thus determines the mechanical and technological properties of the steel. For this reason, for example, one uses powerful cooling devices behind the finishing train, by means of which the desired temperature profile can be set.
• the present invention is therefore based on the object to provide a method and an associated device, with which or with which it is possible to overcome the disadvantages mentioned. Accordingly, an improved control of the course of the temperature according to a desired profile over time or over the conveying path should be possible so as to be able to better control and control the structure development. Furthermore, a more flexible production of micro-alloyed steels, in particular of tubular steels, should be possible.
• the solution of this object by the invention is characterized according to the method by the sequence of the following steps: a) definition of a desired temperature profile for the slab over its run through the plant; b) positioning at least one temperature-influencing element for temperature control of the slab according to the defined temperature profile in the process line of the plant, wherein the temperature-influencing element between the first furnace and the at least one roughing stand and / or between the second furnace and the at least one finish rolling mill is introduced; c) production of the slab or strip in the system thus configured, wherein the at least one temperature-influencing element is operated in such a way that the defined temperature profile is at least largely maintained.
• another oven is used.
• This may be an induction furnace or a furnace that heats the slab by direct flame (DFI oxyfuel furnace).
• DFI oxyfuel furnace direct flame
• the flame is applied directly to the slab by means of a gas jet with at least 75% oxygen into which a gaseous or liquid fuel is mixed.
• a compensation furnace, a roller hearth furnace or a walking beam furnace or pusher furnace can be used.
• a temperature-influencing element and a further cooling section can be used.
• This can be, for example, an intensive cooling section or a laminar belt cooling section.
• a temperature-damping element can also be used as temperature-influencing element (roller-type encapsulation).
• the temperature profile is thereby preferably determined on the basis of a microstructure model.
• the microstructure model preferably defines and / or monitors the following parameters: the temperature profile over time or Number of stitches, the acceptance distribution over time or the number of stitches, the holding or shuttle times, the rolling speeds and transport speeds and / or the heating and cooling intensities.
• a further development envisages that by using a temperature-influencing element in the form of a cooling such a low inlet temperature is achieved in the at least one finishing stand, so that there recrystallization and grain growth largely omitted, the temperature level between the inlet into the at least one Pre-rolling stand and the inlet to the temperature-influencing element in the form of cooling either a) is lowered in particular for tubular steels with low levels of Mikrolegie- elements and low slab thickness by means of a temperature-influencing element in the form of cooling in order to reduce the grain size when entering the finishing train, or b) is increased in particular for tubular steels with high levels of micro-alloying elements and large slab thicknesses by means of a temperature-influencing element in the form of a heater in order to achieve complete recrystallization during rough rolling c) only balanced and otherwise left unchanged.
• the plant for producing a microalloyed steel, in particular a tubular steel, which in the conveying direction of a slab in this order a casting machine, a first furnace, at least one roughing stand, a second furnace, at least one finishing stand and a cooling section, according to the invention is characterized in that between the first furnace and the at least one roughing stand and / or between the second furnace and the at least one finish rolling mill a temperaturbeeinpounden- the element for controlling the temperature of the slab in the process line is selectively introduced, wherein the temperature-influencing element is selectable from one of the elements: another furnace , another cooling section, a temperature-insulating element.
• a refinement provides that at least one of the temperature-influencing elements of the further furnace, further cooling section and temperature-insulating element is arranged transversely displaceable relative to the conveying direction of the slab, that one of the elements can optionally be introduced into the process line.
• At least one of the elements further furnace, further cooling section and temperature-insulating element can be arranged to be pivotable about an axis of rotation pointing in the conveying direction, that one of the elements can optionally be introduced into the process line.
• the temperature can be either raised, kept constant or lowered both before the roughing mill and between the roughing train and the finishing train.
• the proposed procedure or device allows a targeted influencing of the temperature of the slab before Vorwalzung depending on material analysis, material dimensions and material properties.
• a targeted influencing of the temperature of the pre-strip before the finish rolling is possible depending on the material analysis, material dimensions and material properties.
• the targeted control of the temperature control during the individual process steps is preferably carried out by the use or the use of a structural model.
• the structure model determines - as already mentioned - the course of the following parameters and monitors them:
• Heating and cooling intensities Furthermore, a targeted control of the different types of Entfes- s Drvorêtn during the individual process steps and an associated control of the material properties can be done.
• the method can be used for different thermomechanical treatments.
• the installation of slab cooling can be done before the pre-deformation of the slab in the roughing stand.
• installation of induction heating or DFI oxyfuel heating may be done prior to pre-deformation in the roughing stand.
• the various cooling and heating units can be replaced by moving or swiveling.
• FIG. 1 is a schematic side view of a casting rolling mill according to a first embodiment of the invention with casting machine, first furnace, roughing line, second furnace, finishing train and cooling section (s),
• FIG. 2 shows an alternative embodiment of the casting and rolling plant according to a second exemplary embodiment
• FIG. 3 shows a further alternative embodiment of the casting-rolling plant according to a third exemplary embodiment
• FIG. 2 shows an alternative embodiment of the casting and rolling plant according to a second exemplary embodiment
• FIG. 3 shows a further alternative embodiment of the casting-rolling plant according to a third exemplary embodiment
• FIG. 2 shows an alternative embodiment of the casting and rolling plant according to a second exemplary embodiment
• FIG. 3 shows a further alternative embodiment of the casting-rolling plant according to a third exemplary embodiment
• FIG. 6 shows a further alternative embodiment of the casting and rolling plant according to a sixth exemplary embodiment
• FIG. 7 is a schematic view of a cast rolling mill in plan view according to a further embodiment
• Fig. 8 schematically illustrated temperature-influencing elements
• FIG. 9 shows a further alternative embodiment of the temperature-influencing elements to FIG. 8 according to a second embodiment of the invention.
• Fig. 10 is a to Fig. 8 further alternative embodiment of the temperature-influencing elements according to a third embodiment of the invention.
• FIG. 11 shows a further alternative embodiment of the temperature-influencing elements according to a fourth embodiment of the invention, with reference to FIG. 8.
• Typical dimension of the slab may be a thickness between 50 to 150 mm and a width between 900 and 3,000 mm.
• a first furnace 4 a roughing mill for rolling the slab, wherein only a single roughing stand 5 is shown (sometimes also several roughing stands are provided), a second furnace 6, a finishing train for rolling the slab or strip, with only a single finishing stand 7 is shown (usually several finishing mills are provided) and a cooling section 8th.
• a pair of scissors 12 is arranged, with which the slab 1 can be cut to a desired slab length (alternatively, a flame cutting machine can be used).
• a scale scrubber 13 is arranged between the first furnace 4 and the roughing stand 5.
• Another tinder scrubber 14 is also located immediately before the finishing mill stand 7. Behind the cooling section 8 is - in a known manner - a reel 15 is provided which winds the finished tape.
• Tubular steels are subject to increased demands with regard to the temperature control of the slab or strip on their way through the plant 2.
• the desired temperature profile over the time or over the conveying path in the conveying direction F is determined.
• a computer-aided fabric model is preferably used, which is known as such and which defines in a professional manner, as the temperature of the slab 1 and the band to run, so that an optimal product can be manufactured.
• Exemplary data for such a temperature profile can be found below by 2 specific temperature ranges of the slab 1 and the band are specified for specific locations of the manufacturing plant.
• the temperature-influencing element 9 is a cooling section, which is effectively introduced behind the second furnace 6 into the process line. This can be an intensive cooling or a laminar cooling, depending on the cooling power required to achieve the desired temperature profile.
• a continuous or reversing finish rolling takes place in the at least one finish rolling stand 7, wherein preferably a number of finish rolling stands are provided, that is to say a finish rolling stand.
• the finish rolling takes place on the desired finished strip thickness and finished strip temperature, followed by the cooling of the strip in the cooling section 8 followed.
• the winding of the tape takes place on the reel 15. Instead of winding the finished rolled strip, it can alternatively be fed directly to the finishing.
• a temperature range of 850 to 950 0 C behind the furnace 6 and the cooling 9 is provided for the finish rolling of tubular steel as part of a classical thermo-mechanical treatment.
• the low inlet temperature ensures that during the almost isothermal rolling in the finishing train recrystallization and grain growth largely avoided and almost the entire deformation is accumulated, so that in the subsequent transformation results in a very fine-grained structure.
• Other requirements are a sufficiently low final rolling temperature of typically less than 820 ° C and a sufficiently high cooling rate in the cooling section.
• it may be necessary to reduce the temperature. temperature of the band already before entering the roughing stand 5 to influence. 2 shows a plant 2 for the production of tube steels according to API, in which the rear part of the first furnace 4 has been replaced by a belt cooling 10. More precisely, an additional cooling section 10 has been introduced into the process line as temperature-influencing element 10 here.
• thermomechanical treatment By cooling the slab, the extent of thermomechanical treatment can be further increased and grain growth between roughing and finish rolling lines can be restricted. Nevertheless, complete recrystallization must still be ensured, which is why this procedure is particularly suitable for tubular steels with low contents of micro-alloying elements and lower slab thicknesses.
• thermoelectric heating to higher temperatures may be expedient in order to allow higher degrees of deformation and to ensure complete dynamic or static recrystallization.
• the elevated temperature can have a favorable effect on the solution state of the micro-alloying elements.
• FIG. An embodiment of the invention which makes this possible in a particularly advantageous manner is shown in FIG.
• a temperature-influencing element 10 in the form of an induction heater has been introduced into the process line behind the first furnace 4 and upstream of the rough rolling mill 5.
• FIGS. 4, 5 and 6 show system concepts in which, in comparison with the solution according to FIGS. 2 and 3, the strip cooling arranged before the finish rolling has been replaced by an induction heater or a furnace.
• the strip cooling 9 in FIGS. 1, 2 and 3
• the induction heating 10 in FIG. 3 and in FIG. 5
• 9 in FIG ) are designed to be displaceable or pivotable in the direction transverse to the conveying direction F and either one or the other unit 9, 10 can be activated.
• a conventional compensation furnace 9, 10 can be moved into the process line as an alternative to FIG. 4. This applies to the various units in front of and behind the rough rolling mill.
• the casting machine 3 may be in the process line with the rolling train 5 or be arranged separately from it. Reference is made to Fig. 7, where in the plan view a corresponding example can be seen.
• Fig. 7 where in the plan view a corresponding example can be seen.
• the slab 1 can be moved from the upper two process lines L to the lower process line L in the transverse direction Q to the conveying direction F; in the lower process line are the other plant parts for the production of the strip.
• the lower process line L also has a casting machine 3, behind which a pair of scissors 12 is arranged.
• the slab 1 is heated to a rough rolling temperature of about 1100 to 1200 0 C.
• the roughing takes place on one or alternatively on several roughing stands 5 continuously or reversibly to an intermediate thickness.
• a second oven 6 is arranged as a holding furnace.
• the holding furnace 6 provides sufficient space to fully absorb a 5 formed in the roughing stand 5 thin slab can. There may also be a short oscillation of the transformed thin slab in the furnace 6.
• a holding furnace 6 can also be a roller-skated encapsulation or a normal roller table be arranged here.
• a temperature-influencing element 9 is positioned in the form of a cooling line in the process line L, with which the slab 1 can be brought to the desired temperature before the finish rolling in the finishing stand 7.
• the belt cooling 9 can also be located in front of the holding furnace or before the roller skating encapsulation. Details on the replacement of the various units by lateral shifting or swinging in or out of the temperature-influencing Elements 9, 10 are sketched in FIGS. 8 to 11. Optionally, it can also be ensured by suitable traversing that three different units share a place in the process line.
• FIG. 8 it can be seen how alternatively an additional furnace (on the left in FIG. 8) or an induction furnace (on the right in FIG. 8) can be moved into the process line L by shifting in the transverse direction Q. Dodge positions 16, 16 'on both sides of the process line L allow the simultaneous displacement of the two ovens from the illustrated position to the right and vice versa.
• the analogous situation is sketched in FIG. 9 for temperature-influencing elements 9, 10 which can be introduced alternatively into the process line L, in the form of a cooling (left in FIG. 9) and an induction furnace (on the right in FIG. 9). Again, the analogous to Fig. 10 applies to a roller hearth furnace (left) and slab cooling (right).
• a temperature-influencing element 9 in the form of a cooling bar can be pivoted about an axis of rotation 11 in order to engage or disengage it.
• the induction furnace 10 is again arranged transversely displaceable in the direction Q to - when it is to be disengaged - to move it to the avoidance position 16 '.

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Citations (12)

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• 2009
  • 2009-08-06 DE DE102009036378A patent/DE102009036378A1/de not_active Withdrawn
• 2010
  • 2010-08-05 RU RU2012108376/02A patent/RU2491356C1/ru active
  • 2010-08-05 CN CN201080045612.2A patent/CN102549173B/zh active Active
  • 2010-08-05 KR KR1020127004086A patent/KR20120047950A/ko active Search and Examination
  • 2010-08-05 WO PCT/EP2010/004814 patent/WO2011015365A1/de active Application Filing
  • 2010-08-05 JP JP2012523247A patent/JP6033681B2/ja active Active
  • 2010-08-05 US US13/388,172 patent/US20120160377A1/en not_active Abandoned
  • 2010-08-05 EP EP10745149.4A patent/EP2462248B1/de active Active

Patent Citations (13)

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