EP0382702B1 - Verfahren zur Herstellung einer dünnen Stahlbramme durch Stranggiessen - Google Patents

Verfahren zur Herstellung einer dünnen Stahlbramme durch Stranggiessen Download PDF

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Publication number
EP0382702B1
EP0382702B1 EP90870018A EP90870018A EP0382702B1 EP 0382702 B1 EP0382702 B1 EP 0382702B1 EP 90870018 A EP90870018 A EP 90870018A EP 90870018 A EP90870018 A EP 90870018A EP 0382702 B1 EP0382702 B1 EP 0382702B1
Authority
EP
European Patent Office
Prior art keywords
slab
less
cooling
thin
process according
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.)
Revoked
Application number
EP90870018A
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English (en)
French (fr)
Other versions
EP0382702A2 (de
EP0382702A3 (de
Inventor
Stéphan Wilmotte
Paul Naveau
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.)
Centre de Recherches Metallurgiques CRM ASBL
Original Assignee
Centre de Recherches Metallurgiques CRM ASBL
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.)
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Publication date
Application filed by Centre de Recherches Metallurgiques CRM ASBL filed Critical Centre de Recherches Metallurgiques CRM ASBL
Publication of EP0382702A2 publication Critical patent/EP0382702A2/de
Publication of EP0382702A3 publication Critical patent/EP0382702A3/de
Application granted granted Critical
Publication of EP0382702B1 publication Critical patent/EP0382702B1/de
Anticipated expiration legal-status Critical
Revoked legal-status Critical Current

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    • 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

Definitions

  • the present invention relates to a method for manufacturing a thin steel slab by continuous casting according to the preamble of claim 1.
  • a thin slab is a rectangular product having the usual width of a continuous casting slab, but whose thickness is less than 100 mm and more precisely is between 60 mm and 20 mm.
  • the continuously cast slabs have a significantly greater thickness, which is generally of the order of 200 mm. They are intended for the manufacture of flat products, such as strips or sheets of various thicknesses.
  • the classic way of this production consists in reducing the thickness of the slab to the desired final value, by a series of rolling operations ranging from roughing to finishing. These multiple rolling operations require prior reheating, powerful and bulky installations, and are ultimately very expensive.
  • a thin slab constitutes an intermediate product the production of which requires the execution of several of the abovementioned operations, namely at least the roughing operations.
  • the casting speed of current continuous casting machines is limited to around 3 m / min. It will be recalled that the casting speed is in fact the speed with which the slab is extracted from the casting mold. On the one hand, it is necessary to ensure the formation of a solidified skin of sufficient thickness at the outlet of the mold and on the other hand to guarantee the complete solidification of the slab before cutting and preferably before the straightening point.
  • the casting speed could be increased while ensuring the formation of the required solidified skin, by appropriately increasing the length of the mold.
  • this increases the friction forces on the slab and increases the risk of breakthrough by tearing the solidified skin.
  • An increase in the casting speed also leads to an increase in the metallurgical length, that is to say the length of the liquid well. To keep this metallurgical length within the desired limits, it is therefore necessary to ensure complete solidification of the slab in a shorter time. In this respect, an increase in the length of watered has little effect; on the other hand, an increase in the flow rate of the nozzles in the secondary cooling zone intensifies the cooling and reheating cycles to which the skin of the slab is subjected alternately and increases the risk of cracking of the solidified skin.
  • secondary cooling should be applied for a time and / or with an intensity allowing the formation of a solidified skin having a sufficient thickness.
  • the object of the present invention is to propose a method for manufacturing a thin steel slab by continuous casting, which allows on the one hand to substantially increase the casting speed while avoiding the aforementioned drawbacks and on the other hand to eliminate several of the costly rolling operations mentioned above.
  • the method of the invention also makes it possible to manufacture a thin slab capable of directly feeding a hot rolling train of steel strips.
  • a method of manufacturing a thin steel slab by continuous casting in which the steel is poured into a mold where it undergoes primary cooling, and at least the outlet section of which has a smaller width or equal to 60 mm, extracts from the mold a slab having a thickness less than 60 mm and having a solidified skin, then submits the slab to a secondary cooling during which an uninterrupted layer of pressurized coolant is formed on at least part of the surface of the slab and ensures the flow of coolant over the surface of the slab in the direction of progression -ci, is characterized in that the thin slab is cooled, during secondary cooling, to a surface temperature below 800 ° C and preferably below 600 ° C.
  • this layer of coolant allows the application on the outer face of the solidified skin, of a pressure at least partially compensating for the ferrostatic pressure existing on the inner face and of this fact achieves support for this skin.
  • the pressure applied by the liquid layer on the product can be adjusted between 0.2 bar and 2 bar.
  • the casting speed is greater than 3 m / min, and preferably between 6 m / min and 20 m / min.
  • said uninterrupted layer of coolant is kept under pressure for a period such that the solidified thickness is at least equal to 5 mm, and preferably greater than 7 mm for a slab of 20 mm thick. and 10 mm for a slab 40 mm thick.
  • cooling according to the invention therefore makes it possible to increase the casting speed, without risk of breakthrough, while retaining the same metallurgical length.
  • the surface temperature of the slab is substantially between 750 ° C and 900 ° C. This temperature level is much lower than that which is encountered with traditional cooling by sprinklers, where the temperature is usually of the order of 1150 ° C. to 1250 ° C.
  • An additional feature is to laminate the thin slab into a hot strip, either while the core is still in a pasty state, or immediately after the slab is fully solidified, said rolling preferably being carried out continuously.
  • FIG 1 illustrates the principle of the method of the invention by means of an implementation device, shown very schematically.
  • This ingot mold 1 is conventionally made of copper and cooled with water. It can also be in the form of 2 wheels or 2 strips, cooled with water between which the steel flows.
  • the steel undergoes primary cooling (zone A) which causes a thin surface film to solidify, then it leaves the mold 1 in the form of a thin slab 2, 40 mm thick, with a thin solid film with a thickness of at least 3 mm.
  • the slab 2 then enters the secondary cooling zone B where it is subjected to intense and continuous cooling by means of an uninterrupted layer 3 of pressurized coolant liquid.
  • This layer 3 is here formed by means of a device 4 known per se, which is not part of the present invention and which it is not necessary to describe in detail. However, it should be noted that this device does not touch the slab at any point and that it does not therefore cause any friction force.
  • the secondary cooling zone B is symbolized here by a single device 4; it goes without saying that this zone B could, as necessary, comprise several separate devices 4, possibly separated by support rollers.
  • the slab 2 At the exit from the secondary cooling zone B, the slab 2 has a thicker solidified skin and the cooling by the pressurized liquid ceases. The slab then moves in the air while continuing its solidification (zone C).
  • the slab 2 can then be transmitted, preferably directly, to a hot rolling stand symbolized by the cylinders 5.
  • Figure 2 illustrates the evolution of the surface temperature of the slab (T s - left vertical axis) and the thickness of the solidified skin (e - right vertical axis) as a function of the distance from the meniscus (L - horizontal axis).
  • Curves (b) and (d) show that the metallurgical length is the same in both cases.
  • Figure 2 shows that conventional secondary cooling has little effect on the temperature reached at the outlet of the ingot mold (curve a); surface temperature at the point of solidification total is of the order of 1200 ° C. This very high value, as well as the low speed value, are unfavorable elements for direct rolling.
  • cooling according to the invention causes a rapid reduction in this surface temperature, followed by heating in zone C to a temperature of around 850 ° C (curve c), which, combined with a high casting speed is a favorable element for direct rolling of the slab.
  • the method of the invention therefore makes it possible to manufacture thin steel slabs by continuous casting at a speed significantly higher than the usual speed, and to supply these slabs under temperature and structural conditions favorable to direct rolling.
  • the slabs thus produced are less prone to segregation.
  • their manufacture by the process of the invention makes it possible to avoid numerous rolling operations, in particular roughing, as well as the reheating which precedes them.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Continuous Casting (AREA)
  • Metal Rolling (AREA)
  • Treatment Of Steel In Its Molten State (AREA)

Claims (7)

  1. Verfahren zur Herstellung einer dünnen Stahlbramme durch Strangguß, bei dem man den Stahl in eine Form gießt, wo er einer primären Kühlung unterworfen wird, wobei mindestens deren Ausgangsquerschnitt eine Breite aufweist, die kleiner als oder gleich 60 mm ist, aus der Form eine Bramme mit einer kleineren Dicke als 60 mm und mit einer erstarrten Haut abzieht, die Bramme dann einer sekundären Kühlung unterwirft, in deren Verlauf man eine ununterbrochene Kühlflüssigkeitsschicht unter Druck auf mindestens einen Teil der Brammenoberfläche bildet, und für einen Abfluß der Kühlflüssigkeit auf der Brammenoberfläche in deren Laufrichtung von deren Vorschub sorgt, dadurch gekennzeichnet, daß die Bramme während der sekundären Kühlung bis auf eine Oberflächentemperatur unter 800°C abgekühlt wird.
  2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Bramme während der sekundären Kühlung bis auf eine Oberflächentemperatur unter 600°C abgekühlt wird.
  3. Verfahren nach einem der Ansprüche 1 und 2, dadurch gekennzeichnet, daß die Gießgeschwindigkeit über 3 m/min liegt.
  4. Verfahren nach Anspruch 3, dadurch gekennzeichnet, daß die Gießgeschwindigkeit zwischen 6 m/min und 20 m/min liegt.
  5. Verfahren nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß man besagte ununterbrochene Kühlflüssigkeitsschicht unter so lange Druck hält, daß die Dicke der erstarrten Haut mindestens gleich 5 mm wird.
  6. Verfahren zur Verwendung einer gemäß einem der Ansprüche 1 bis 5 hergestellten dünnen Bramme, dadurch gekennzeichnet, daß man diese dünne Bramme direkt zu ein Warmwalzband walzt.
  7. Verfahren nach Anspruch 6, dadurch gekennzeichnet, daß dieses Aufwalzen kontinuierlich erfolgt.
EP90870018A 1989-02-10 1990-02-05 Verfahren zur Herstellung einer dünnen Stahlbramme durch Stranggiessen Revoked EP0382702B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
BE8900138 1989-02-10
BE8900138A BE1002826A6 (fr) 1989-02-10 1989-02-10 Procede de fabrication d'une brame mince en acier par coulee continue.

Publications (3)

Publication Number Publication Date
EP0382702A2 EP0382702A2 (de) 1990-08-16
EP0382702A3 EP0382702A3 (de) 1991-06-12
EP0382702B1 true EP0382702B1 (de) 1997-04-09

Family

ID=3884009

Family Applications (1)

Application Number Title Priority Date Filing Date
EP90870018A Revoked EP0382702B1 (de) 1989-02-10 1990-02-05 Verfahren zur Herstellung einer dünnen Stahlbramme durch Stranggiessen

Country Status (4)

Country Link
EP (1) EP0382702B1 (de)
AT (1) ATE151321T1 (de)
BE (1) BE1002826A6 (de)
DE (1) DE69030396D1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110421002A (zh) * 2019-07-08 2019-11-08 江苏煌明能源科技有限公司 棒线材无加热炉连铸直轧工艺

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3616844A (en) * 1970-02-24 1971-11-02 Benteler Geb Paderwerk Apparatus for continuous casting of metal ingots
FR2153152A1 (en) * 1971-09-21 1973-05-04 Creusot Loire Continuous casting curved cooling guide - improves casting quality by supporting it on pressurised fluid and rollers
US3918467A (en) * 1972-01-21 1975-11-11 Siderurgie Fse Inst Rech Apparatus for the cooling of a continuously cast product
CH616354A5 (en) * 1976-09-23 1980-03-31 Hitachi Ltd Continuous casting apparatus
ATE47061T1 (de) * 1986-03-18 1989-10-15 Centre Rech Metallurgique Verfahren und vorrichtung zum kuehlen von strangguss aus metall.

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110421002A (zh) * 2019-07-08 2019-11-08 江苏煌明能源科技有限公司 棒线材无加热炉连铸直轧工艺

Also Published As

Publication number Publication date
EP0382702A2 (de) 1990-08-16
EP0382702A3 (de) 1991-06-12
BE1002826A6 (fr) 1991-06-25
DE69030396D1 (de) 1997-05-15
ATE151321T1 (de) 1997-04-15

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