EP0098214A1 - Verfahren und Vorrichtung zum elektromagnetischen Rühren von stranggegossenen Metallen, insbesondere Stahl - Google Patents

Verfahren und Vorrichtung zum elektromagnetischen Rühren von stranggegossenen Metallen, insbesondere Stahl Download PDF

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Publication number
EP0098214A1
EP0098214A1 EP83401299A EP83401299A EP0098214A1 EP 0098214 A1 EP0098214 A1 EP 0098214A1 EP 83401299 A EP83401299 A EP 83401299A EP 83401299 A EP83401299 A EP 83401299A EP 0098214 A1 EP0098214 A1 EP 0098214A1
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EP
European Patent Office
Prior art keywords
magnetic field
metal
cast
level
casting
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Ceased
Application number
EP83401299A
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English (en)
French (fr)
Inventor
Jean-Pierre Birat
Jeanne Chone
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Institut de Recherches de la Siderurgie Francaise IRSID
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Institut de Recherches de la Siderurgie Francaise IRSID
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Publication of EP0098214A1 publication Critical patent/EP0098214A1/de
Ceased 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
    • B22D11/122—Accessories for subsequent treating or working cast stock in situ using magnetic fields
    • 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

Definitions

  • the present invention relates to the electromagnetic stirring of metals, in particular steels, continuously cast. It is particularly applicable to metals, or steels, having a wide solidification range.
  • the continuous casting operation consists schematically of continuously pouring the molten metal into a bottomless, energetically cooled ingot mold, generally made of copper or copper alloy, from which is extracted, also continuously, a bar having a crust external solidified and whose core still liquid gradually solidifies during its extraction, downstream of the mold, in the area called “secondary cooling" of the casting machine.
  • the distance over which the poured product passes from a completely liquid state (surface of the liquid metal in the mold, or "meniscus") to a completely solidified state (bottom of the solidification well) is usually called "metallurgical height" and this whatever the trajectory of the casting bar, vertical or curved.
  • the object of the present invention is precisely to allow, by continuous casting of steel, or other metal alloys with a large solidification interval, the production of semi-finished products having a low axial segregation, or at least, an axial segregation substantially less than that which would be obtained by the known techniques of continuous casting.
  • the subject of the invention is an electromagnetic stirring process, during the continuous casting of metals, in particular steels having a large solidification interval, according to which the molten molten metal is rotated about the axis.
  • a magnetic field is implemented consisting of a plurality of successive rotating elementary magnetic fields, arranged in a stepped fashion on said portion of the metallurgical height and whose directions of rotation are opposite two by two.
  • the rotating magnetic field is already made to act slightly upstream of said portion of the metallurgical height, in order to compensate for the delay in rotation which the liquid metal opposes due to its inertia.
  • the direction of rotation of the magnetic field is periodically reversed over time.
  • the invention also relates to a continuous casting installation for the implementation of the method, which is characterized in that it comprises, in the secondary cooling zone, a battery of inductors with mobile magnetic field for the mixing of the liquid metal, arranged in a staggered manner, successively one after the other along the metallurgical height, on a portion of the latter extending, at least, from the level at which the liquid core of the cast product reaches the temperature of liquidus of the cast metal, up to the level at which the proportion of solid in the still liquid phase is about 40 ⁇ by weight.
  • the invention consists in its essential characteristics, of brewing the metal when the state of progress of the solidification of the latter gives it a consistency which is not yet completely solid, or more completely liquid and that we will qualify, to fix the idea, of "pasty".
  • the term “paste-like” consistency, zone or solidification is intended to characterize the state of solidification of a continuously cast metal, the enthalpy of which lies between the enthalpy of the completely solid metal and the enthalpy of completely liquid metal.
  • the position and extent of the "pasty" zone are determined from the determination of the temperature of the metal on the casting axis and it is considered that the "pasty" zone is the portion of the metallurgical height between the levels upper and lower temperature corresponding respectively to the liquidus temperature and the solidus temperature of the cast metal.
  • intersections of these two fronts with the pouring axis determine between them, in magnitude and position, the portion of the metallurgical height where solidification of the type takes place. "pasty”, and in which according to the invention, the magnetic field (s) of alternating rotation are acted upon.
  • this pasty solidification zone is characterized by the birth of a solid phase within the liquid phase itself and by the increase in the proportion of this solid phase as the cast product cools down to '' to total solidification corresponding to the closing of the solidification well (intersection of the pouring axis with the ending solidification front).
  • Figure 1 illustrates well what has been said previously about the progress of solidification in continuous casting.
  • the vertical arrow pointing downwards indicates the direction of extraction of the product.
  • the side surface of the product - which is energetically cooled - in 2 the product axis (merged with the pouring axis), in 3 the free surface of the metal in the mold, in 4 the completely liquid metallic phase , in 5 the metal completely solidified and, in 6 and 7, respectively the fronts of starting and ending solidification delimiting between them a zone 8 semi-solid, semi-liquid (whose liquid phase is besides strongly segregated in elements of 'alloy).
  • the beginning solidification front 6 defines, with very good approximation, the isothermal surface of liquidus T L of the cast metal. It is the same for the ending solidification front 7 as regards the solidus temperature T 5 .
  • the intersections of the casting axis 2 respectively with the beginning solidification front 6 and the ending solidification front 7, intersections identified in the figure by the two points T L and T S define between they the portion, denoted ⁇ h of the metallurgical height (denoted ⁇ H) and which, in accordance with the invention, constitutes the field in which the stirring magnetic field or fields are made to act.
  • the graph of FIG. 1 in addition to its purely illustrative role of the phenomena explained above, also reflects the quantitative results obtained during test runs of steels of grade 100 C6 for which the physicochemical data and the operating conditions are recorded. respectively in the tables of values 1 and 2 below.
  • the metallurgical height ⁇ H is approximately 15.5 m and the level of T L has been determined at a height of 4.5 m.
  • We therefore calculate a zone ⁇ h, corresponding to the pasty zone, of length: 15.5 - 4.5 11 m, initiating at 4.5 m under the meniscus 3.
  • the temperature field at any level of the metallurgical height. From, for example, a simple enthalpy diagram - temperature "of the casting grade, it is then easy to construct the curve, referenced 9 in FIG. 1, intermediate between the fronts of finishing and beginning solidification, and representing the place of the points in the liquid phase where the proportion of liquid phase is 40% by weight. More simply, one can be satisfied with determining the point of intersection T. of this curve with the pouring axis 2, this point T i then defining, with the point T L placed upstream, the portion denoted 6h, of the pasty zone ⁇ h, along which, in accordance with the invention, the metal is stirred.
  • the proposed solution consists in electromagnetically mixing the liquid metal in the pasty zone dh, more simply along the portion Sh (fig 1) of this zone, in order to counteract the tendency of the metal to form these segregated channels.
  • the brewing is initiated slightly upstream of the 6 h portion in order to, as already pointed out, to compensate for the delay which the inertia of the liquid metal opposes to the brewing movement, in particular when the brewing consists in making rotate the liquid metal around the casting axis.
  • the inventors have been able to show that it is advantageous to seek a shearing effect of the liquid metal against the solidification front, this effect being obtainable, in accordance with the invention, by means of repetitive reversals of the direction of movement of the stirring magnetic field.
  • FIG. Z shows, in correspondence of scale and dimensions with the diagram of FIG. 1, the location of the stirring inductors for the implementation of the invention according to a variant with successive rotating and alternating magnetic fields along the axis of: oulée.
  • a so-called “vertical” continuous casting installation has been schematically represented (ie entirely straight trajectory of the casting bar) comprising, from the top of the installation, a distributor 10 supplying molten metal continuously, by a pouring jet 11, a bottomless ingot mold 12. From the latter is extracted, also continuously, a bar 13 having a solidified outer crust 5 and the still liquid core 4 of which progressively solidifies during its extraction ( in the direction indicated by the arrow) over the total distance ⁇ H called "metallurgical height".
  • a shear symbolized at 14 cuts the bar by accompanying it in its descent. Once cut, the section is tilted and immediately removed to allow the casting process to continue.
  • the ingot mold 12 is a boxed mold of known type, essentially comprising an internal tubular element 14, made of copper, defining a passage for the cast product and energetically cooled on its external face by a casing of water 15 in upward circulation from a chamber of supply 16 to an upper evacuation chamber 17.
  • the upper evacuation chamber 17 has been sufficiently dimensioned to be able to immerse therein an electromagnetic stirring inductor 18.
  • This inductor the role of this inductor, the presence of which is desirable but in no way essential for the implementation of the invention , will be specified later.
  • the same remark also applies to the inductor 19 placed downstream of the mold and acting, as can be seen, already upstream the pasty solidification zone ⁇ h.
  • a battery of stepped inductors (here three in number) 20, 20 ′, 20 "surrounds the bar cast on the 6h portion of the metallurgical height ⁇ H.
  • These inductors with rotating magnetic field, annular in shape and polyphase static type, are stirring devices electromagnetic known and used in the field of continuous casting. A detailed description can be found, if necessary, by referring, for example, to French patent No. 2,211,305 (CEM).
  • each inductor delivers a rotating magnetic field whose direction of rotation is opposite to that of, or inductors which are immediately adjacent to it.
  • the inductors 20, 20 ′, 20 ′′ deliver magnetic fields rotating in the same direction at the same time, in which case it is advantageous, for the reasons already mentioned, to periodically reverse the direction of rotation of the field.
  • the rule to be observed is that any elementary volume of liquid metal which, during the extraction of the cast product, penetrates into the portion 6h is, before leaving it, subjected to a magnetic field whose direction of rotation reverses at least once.
  • this rule obviously depends on the local operating conditions and, in particular, on the speed of extraction of the cast product, in connection with the length of the brewed portion 6 hours.
  • the minimum residence time of any elementary volume of metal in the stirred portion 6h is therefore approximately 6 and a half minutes.
  • the aforementioned rule is observed if one brews in each direction for example for about 3 minutes, an exposure time of a few tens of seconds. between the two shuffling sequences then being provided for the natural attenuation of the movement before turning back in the direction of circulation.
  • the size of the inductor 19 has been voluntarily reduced compared to that of the inductors 20, 20 ′, 20 ", with the sole aim of clearly differentiating it so as not to harm the understanding of the It is clear that its size, as well as its implementation, can be quite similar to that of the inductors 20.
  • the liquid metal is further subjected. to a stirring already within the mold 12.
  • a stirring already within the mold 12 this can be done using the electromagnetic inductor 18 housed in the upper water chamber 17.
  • the inductor 18, retained in this example is of the polyphase static type surrounding the cast product and delivering a rotating magnetic field. It will be recalled that the production of inductors of this kind, as well as their use within a continuous casting mold as a device for stirring the metal, as well as the favorable results of such stirring on the metallurgical quality of the products obtained, are already part of the known state of the art (aforementioned patents).
  • the originality of the variant of the invention presented here lies in the combination of mixing in an ingot mold and mixing in a pasty zone Ah, leading to a beneficial conjugation of their effects, which are manifested in particular by obtaining a well of shallower solidification and flattened bottom, so that the portion ⁇ h to be brewed is, on the one hand, shortened in height and, on the other hand, widened in section, which goes in the direction of stirring in the times more economical and more efficient.
  • FIGS. 3 are photographic reproductions of "Raumann” impressions made in longitudinal axial section of the cast product (grade 100C6 steel). They illustrate, by highlighting the segregation of sulfur, the comparative metallurgical results obtained between an unmixed product (Figure 3a) and a product brewed, on the one hand, using a permanent rotating magnetic field ( Figure 3b), on the other hand, using an alternating rotating magnetic field ( Figure 3c).
  • the term “at least” should be understood as used above in the expression “... it is important that the liquid metal be brewed ... at least in the 6h portion ... ", the possibility, not only to initiate brewing upstream of this portion to compensate for the inertia of the metal, but also to continue the brewing action downstream of the level Ti on the metallurgical height where the proportion by weight of solid in the liquid phase reaches 40%. It will be understood, however, that there is little point, in the context of the results targeted by the invention, of continuing to be stirred up to the close vicinity of the bottom Ts of the solidification well.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Continuous Casting (AREA)
EP83401299A 1982-06-28 1983-06-23 Verfahren und Vorrichtung zum elektromagnetischen Rühren von stranggegossenen Metallen, insbesondere Stahl Ceased EP0098214A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8211446A FR2529117B1 (fr) 1982-06-28 1982-06-28 Procede de brassage electromagnetique des metaux, notamment des aciers, coules en continu et dispositif de mise en oeuvre
FR8211446 1982-06-28

Publications (1)

Publication Number Publication Date
EP0098214A1 true EP0098214A1 (de) 1984-01-11

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EP83401299A Ceased EP0098214A1 (de) 1982-06-28 1983-06-23 Verfahren und Vorrichtung zum elektromagnetischen Rühren von stranggegossenen Metallen, insbesondere Stahl

Country Status (8)

Country Link
EP (1) EP0098214A1 (de)
JP (1) JPS5985353A (de)
KR (1) KR840005157A (de)
AU (1) AU1615483A (de)
CA (1) CA1204575A (de)
ES (1) ES8403763A1 (de)
FR (1) FR2529117B1 (de)
ZA (1) ZA834536B (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0384174A2 (de) * 1989-02-23 1990-08-29 Km-Kabelmetal Aktiengesellschaft Verfahren zur Überwachung des Erstarrungsvorgangs beim kontinuierlichen Stranggiessen
WO2009117803A1 (en) * 2008-03-25 2009-10-01 Abb Inc. Modulated electromagnetic stirring of metals at advanced stage of solidification

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7827950B2 (en) * 2007-06-27 2010-11-09 Federal-Mogul Corporation Valve cover assembly and method of construction

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1086957A (fr) * 1952-08-27 1955-02-17 Procédé de coulée
FR1115505A (fr) * 1953-12-17 1956-04-25 Mannesmann Ag Inducteur à champ tournant et à encoches, à flux magnétique fermé pour appareillage de coulée continue
FR2236584A1 (de) * 1973-05-21 1975-02-07 Siderurgie Fse Inst Rech
US4016926A (en) * 1974-03-23 1977-04-12 Sumitomo Electric Industries, Ltd. Electro-magnetic strirrer for continuous casting machine
DE2922203B1 (de) * 1979-05-29 1980-09-04 Mannesmann Ag Verfahren zum elektromagnetischen Ruehren einer Schmelze
DE2912539A1 (de) * 1979-03-29 1980-10-09 Licentia Gmbh Vorrichtung zum elektrodynamischen ruehren des sumpfes in einer stranggegossenen erstarrenden metallbramme

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1086957A (fr) * 1952-08-27 1955-02-17 Procédé de coulée
FR1115505A (fr) * 1953-12-17 1956-04-25 Mannesmann Ag Inducteur à champ tournant et à encoches, à flux magnétique fermé pour appareillage de coulée continue
FR2236584A1 (de) * 1973-05-21 1975-02-07 Siderurgie Fse Inst Rech
US4016926A (en) * 1974-03-23 1977-04-12 Sumitomo Electric Industries, Ltd. Electro-magnetic strirrer for continuous casting machine
DE2912539A1 (de) * 1979-03-29 1980-10-09 Licentia Gmbh Vorrichtung zum elektrodynamischen ruehren des sumpfes in einer stranggegossenen erstarrenden metallbramme
DE2922203B1 (de) * 1979-05-29 1980-09-04 Mannesmann Ag Verfahren zum elektromagnetischen Ruehren einer Schmelze

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
2048 TECHNIQUES CEM, no. 111, juin 1981, pages 2-10, Paris, FR. *
CAHIERS D'INFORMATIONS TECHNIQUES, vol. 78, no. 3, mars 1981, pages 239-242, Paris, FR. *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0384174A2 (de) * 1989-02-23 1990-08-29 Km-Kabelmetal Aktiengesellschaft Verfahren zur Überwachung des Erstarrungsvorgangs beim kontinuierlichen Stranggiessen
EP0384174A3 (de) * 1989-02-23 1991-03-06 Km-Kabelmetal Aktiengesellschaft Verfahren zur Überwachung des Erstarrungsvorgangs beim kontinuierlichen Stranggiessen
WO2009117803A1 (en) * 2008-03-25 2009-10-01 Abb Inc. Modulated electromagnetic stirring of metals at advanced stage of solidification
EP2268431A4 (de) * 2008-03-25 2017-07-12 ABB Inc. Moduliertes elektromagnetisches rühren von metallen im fortgeschrittenen stadium des erstarrens

Also Published As

Publication number Publication date
CA1204575A (fr) 1986-05-20
FR2529117B1 (fr) 1985-11-15
AU1615483A (en) 1984-01-05
ES523652A0 (es) 1984-04-01
JPS5985353A (ja) 1984-05-17
ZA834536B (en) 1984-03-28
FR2529117A1 (fr) 1983-12-30
KR840005157A (ko) 1984-11-05
ES8403763A1 (es) 1984-04-01

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