US3888294A - Method of continuously casting steel - Google Patents

Method of continuously casting steel Download PDF

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Publication number
US3888294A
US3888294A US473212A US47321274A US3888294A US 3888294 A US3888294 A US 3888294A US 473212 A US473212 A US 473212A US 47321274 A US47321274 A US 47321274A US 3888294 A US3888294 A US 3888294A
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Prior art keywords
casting
section
steel
stream
cross
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US473212A
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English (en)
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Thorwald Fastner
Alois Niedermayr
Ernst Bachner
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Voestalpine AG
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Voestalpine AG
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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
    • B22D11/10—Supplying or treating molten metal
    • B22D11/11—Treating the molten metal
    • B22D11/116—Refining the metal
    • B22D11/117—Refining the metal by treating with gases
    • 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
    • B22D11/10—Supplying or treating molten metal
    • B22D11/11—Treating the molten metal
    • B22D11/111—Treating the molten metal by using protecting powders

Definitions

  • ABSTRACT A continuous steel casting method for a casting capacity of more than 1.5 metric tons of steel per minute, wherein a stream of steel is supplied to below the casting level in the mold through a casting tube having lateral openings and at least one additional bottom opening directed vertically downward and having a cross section smaller than the cross section of the casting tube.
  • the overall cross section of all of the casting tube openings corresponds to at least the clear cross section of the casting tube.
  • the mold inert gas is supplied in a certain amount to the stream of steel over its entire cross section.
  • the invention relates to a continuous steel casting method for a casting capacity of more than L5 metric tons of steel per minute using a vertically arranged, substantially rectangular mold, into which at least one steel stream containing inert gas is passed via a casting tube below the casting level in the mold, the casting tube being provided with lateral openings, whose axes lie in a vertical plane running through the longer trans verse axis of the mold.
  • the casting capacity is raised above 1.5 metric tons of steel per minute, it becomes obvious that the present technology is no longer sufficient; in rapid casting plants for slabs having a thickness of lSO up to 250 mm and a width of 800 up to 2500 mm and more the crack formation and the liability to breakthroughs increases strongly as the casting velocity rises, because the steel flow causes cavitations in the range of the strand skin, which cavitations are all the more critical, the thinner the strand skin. As is known the strand skin thickness diminishes as the casting capacity increases.
  • the steel flow in the liquid phase of the strand is determined substantially by the direction of the axes of the lateral openings of the casting tube.
  • refractory casting tubes with a closed bottom and two lateral openings downwardly inclined and directed towards the narrow sides of the mold.
  • the casting velocity is high mainly edge cracks and breakthroughs in the range of the edges of the strand occur.
  • longitudinal cracks at the broad side of the slab in the range of the strongest flow may occur.
  • nonmetallic inclusions are carried into a great depth of the liquid phase; these have no opportunity to rise and to get into the slag floating on the surface of the liquid steel (casting level).
  • the lateral outlets are directed steeply or perpendicularly upward, the casting level is moved strongly in the mold at a high casting speed, whereby the slag practice in the mold is made difficult.
  • this object is achieved in a continuous steel casting method of the above described type in that a casting tube is used, which, apart from the lateral openings, is provided with a least one additional bottom opening directed vertically downward, whose cross section is smaller than the clear cross section of the casting tube (steel stream), wherein the inclination angle a of the axes of the lateral openings in relation to the horizontal lies within a range of downward up to upward, preferably 10 to 90 upward, and the total cross section of the lateral openings and the bottom openings directed vertically downward of the casting tube corresponds at least to the clear cross section of the casting tube and that the inert gas is supplied to the steel stream over its entire cross section at the place of its origin above the mold in a quantity of l to 15 Ncm/kg steel, preferably of 3 to 8 Ncm /kg steel.
  • Ncm means normal volume, i.e., volume at 0 and 760 mm H
  • the inert gas is, according to a further feature of the invention, supplied coaxially to the steel stream.
  • a refractory tube is used, whose outlet is adjustable at a distance above the bottom of a tundish, in which the casting tube is fastened, wherein this distance is preferably equal or a little smaller than the diameter of the casting tube.
  • a refractory tube for the gas supply one can also use a refractory tube. whose outer diameter is smaller than the inner diameter of the casting tube and whose outlet is adjustable at a distance below the bottom of the tundish, in which the casting tube is fastened, wherein this distance is preferably equal or smaller than the diameter of the casting tube.
  • a further feature of the invention consists in that the cross section of the downwardly directed bottom opening(s) of the casting tube expressed in 7: of the casting tube (steel stream-l cross section in dependence upon the casting capacity expressed in metric tons of steel per minute is adjusted in such a way that at 1.5 metric tons per minute the cross section lies in the range of to 60% and rising proportionately up to a casting capacity of 60 metric tons per minute increases to 50 to 90%.
  • the invention also comprises the use of a suitable slag or slag powder, respectively, which is applied onto the casting level in the mold.
  • This slag serves for receiv ing non-metallic particles from the steel, in particular from aluminum-containing steel, it is easily melted, is produced preferably synthetically and has the following composition:
  • FIG. 1 is a schematic illustration of a vertical section through the upper part of a continuous casting plant with a tundish.
  • FIG. 2 is a longitudinal section through a casting tube to be used in the method according to the invention, wherein various possibilities for the inclination of the axes of the lateral openings in the wall of the casting tube are drawn.
  • FIG. 3 shows the head of a casting tube, where the lateral openings are directed vertically upward.
  • FIG. 4 is a horizontal section through a slab mold and a casting tube with oval cross section, which possesses two bottom openings directed perpendicularly down' ward.
  • FIG. 5 is a graph showing the most favorable cross section for the bottom opening(s) of the casting tube, i.e., on the abscissa the casting capacity is plotted in metric tons per minute and on the ordinate the portion of the cross section of the bottom opening(s) in per cent of the casting tube- (steel stream-) cross section is plotted.
  • FIG. 6 illustrates a modified embodiment of the supply of inert gas to the steel stream.
  • 1 denotes a refractory tundish with a bottom opening 2, which is capable of being closed by a liftable and lowerable refractory stopper 3.
  • the stopper 3 has an axial bore 4, through which, in the direction of the arrow 5, an inert gas at a quantity of l to 15 Ncm /kg steel is supplied; it has been found that ifa gas quantity of less than lNcm lkg steel is supplied, cracks occur in the slabs, whereas with gas quantities higher than 15 Ncm /kg steel the casting level 12 in the mold bubbles too strongly, so that a perfect control of the slag 13 is no longer possible.
  • the outlet of the bore 4 is adjusted above the upper edge of a casting tube 6, respectively the bottom 7 of the tundish l at a distance +a in such a way that the supplied gas is sucked in practically without pressure by the steel flow indicated by the arrows 8 in the range of the bottom opening 2; this is the case when a is equal to or smaller than the diameter d of the bottom opening 2 of the casting tube 6.
  • l7 denotes support and guiding rollers for the strand. Below the oscillating mold 14 spray nozzles (not illustrated) are provided for cooling the strand in the secondary cooling zone till the complete solidification. l8 denotes the quantity of steel present in the tundish 1 and 19 is a slag layer protecting the steel against the influence of the atmosphere.
  • the axes 20 of the lateral casting tube openings 9 lie horizontally in a plane laid through the bigger transverse axis of the mold, which plane corresponds to the plane of the drawing.
  • Non-metallic particles in the steel are washed upward by the gas bubbles into an easily melting slag layer 13 and are taken up by it.
  • the slag is, according to the invention, structured on the basis of C210 and CO with a high content of fluxing agents and a low content of A1 0 the high content of fluxing agents guarantees the rapid melting of the casting powder added under continuous casting conditions; the low Al O -content causes that by the alumina particles washed from the steel into the slag no undesired alteration of the melting behaviour occurs.
  • the slag 19 in the tundish can, but need not have the same chemical composition as the slag 12.
  • FIG. 2 it is shown, which inclinations of the axes 20 of the lateral openings are possible according to the invention: for achieving a good separation effect for the non-metallic particles the axes may be inclined to the horizontal by an angle +0: of ID to i.e. the range lying between 20' and 20". characterized by the angle 0 of 60. is very favorable; if. however. the segregation of the non-metallic particles is only less important.
  • the axis up to the axis 20" may be inclined downward by an angle a of 70.
  • lateral openings 9 are downwardly inclined without gassupply an .increased sedimentation of non-metallic inclusions on the strand skin 16 would occur; by supplying gas and by providing the bottom opening 10, as well as by adjusting an angle of -70 to +70 cach in relation to the horizontal this disadvantage of the hitherto practised continuous casting technology is eliminated.
  • FIG. 3 it is also possible to use a casting tube head 6 with openings 9' directed vertically upward; in this case the axes 20"" enclose with the horizontal an angle of 90".
  • the cross'sectiongiven by the bottom opening with the diameter d is smallertha n the cross section of the casting tube 6. respectively the steel stream. given by the diameter d and that, on the other hand.
  • the sum of the cross sections of the bottom opening and the lateral openings 9 with the diameter :1 is either equal to the cross section of the casting tube or bigger than said cross section.
  • the cross section of the casting tube can. as is shown in FIG. 4, have any shape, e.g..
  • FIG. 5 illustrates the correlation according to the invention between the cross section of the bottom opening(s) l0, l0, l0" and the casting tube (steel stream-l cross section in dependence upon a casting capacity lying in the range between 1.5 and 6.0 metric tons/min. in rapid continuous steel casting plants; the cross section of the bottom openings must lie in field A, so that no cracks occur in the strand.
  • FIG. 6 denotes a refractory tube for the supply with gas, whose cross section is smaller than the cross section of the casting tube 6.
  • This tube 23 is, like the stopper 3, liftable and lowerable.
  • the outlet may also be adjusted at a distance -a below the bottom 7, whereby the inert gas is also sucked in and as a consequence of a strong current in the bottom opening 2 a uniform distribution of the gas bubbles over the entire steel stream cross section occurs; the distance -a is not to be bigger than the tube diameter (1.
  • Such a tube 23 is preferably used, when. below the tundish. a sliding closure is provided for the casting tube arranged below.
  • the casting tube diameter d usually measures about 60 mm. This diameter d should possibly not exceed 40% of the narrow side of the mold (slab thickness); with substantially bigger diameters there is the danger of erosion of the strand skin. With very wide slabs two casting tubes may be arranged side by side, the bottom openings of which have to be dimensioned according to the quantity of steel in metric tons per minute flowing through the casting tube, as is shown in FIG. 5.
  • the invention may be applied in continuous casting procedures for all types of steel, it is however particularly advantageous to use it for wide slabs of aluminumcontaining steel; in particular casting procedure of the invention can be applied for aluminum-killed deep drawing steels containing C 0.03 to 0.0771
  • the axes of the said lateral openings being inclined by between downward and upward in relation to the horizontal and the total cross section of the lateral openings and of the at least one bottom opening being at least equal to the clear cross section ofthe casting tube, and supplying the said inert gas to the said at least one stream of molten steel in an amount of l to 15 Ncm lkg steel over the entire cross section of the stream of molten steel at the place of origin of said at least one stream of molten steel above the mold.
  • a method according to claim 12, wherein the slag is a synthetically produced slag.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Continuous Casting (AREA)
  • Casting Support Devices, Ladles, And Melt Control Thereby (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
US473212A 1973-06-14 1974-05-24 Method of continuously casting steel Expired - Lifetime US3888294A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AT522373A AT331438B (de) 1973-06-14 1973-06-14 Kontinuierliches stahlstranggiessverfahren sowie anlage zur durchfuhrung des verfahrens

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US3888294A true US3888294A (en) 1975-06-10

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US473212A Expired - Lifetime US3888294A (en) 1973-06-14 1974-05-24 Method of continuously casting steel

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US (1) US3888294A (sv)
JP (1) JPS5022719A (sv)
AT (1) AT331438B (sv)
BE (1) BE814094A (sv)
BR (1) BR7404816D0 (sv)
CA (1) CA1022323A (sv)
CH (1) CH575264A5 (sv)
DE (1) DE2428059A1 (sv)
ES (1) ES425951A1 (sv)
FR (1) FR2233121B1 (sv)
GB (1) GB1472576A (sv)
IT (1) IT1005964B (sv)
SE (1) SE7404552L (sv)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3931850A (en) * 1974-03-11 1976-01-13 Mannesmann Aktiengesellschaft Apparatus for feeding and distributing steel melts
US3935895A (en) * 1973-06-14 1976-02-03 Vereinigte Osterreichische Eisen- Und Stahlwerke-Alpine Montan Aktiengesellschaft Continuous steel casting method
US3991815A (en) * 1974-06-25 1976-11-16 Vereinigte Osterreichische Eisen- Und Stahlwerke-Alpine Montan Aktiengesellschaft Casting tube with a bottom opening for continuously casting steel strands
US3996994A (en) * 1974-09-02 1976-12-14 Mannesmann Aktiengesellschaft Supplying molten metal to a mold for continuous casting
US4015655A (en) * 1974-06-25 1977-04-05 Vereinigte Osterreichische Eisen- Und Stahlwerke-Alpine Montan Aktiengesellschaft Process and apparatus for continuously casting strands of unkilled or semi-killed steel
US4064925A (en) * 1975-02-25 1977-12-27 Vereinigte Osterreichische Eisen- Und Stahlwerke-Alpine Montan Aktiengesellschaft Continuous casting method and apparatus
US4520861A (en) * 1983-11-18 1985-06-04 Republic Steel Corporation Method and apparatus for alloying continuously cast steel products
US5205343A (en) * 1989-06-03 1993-04-27 Sms Schloemann-Siemag Aktiengesellschaft Pouring tube for feeding molten steel into a continuous casting mold
EP0648561A1 (en) * 1993-10-13 1995-04-19 Nkk Corporation Immersion nozzle for continuous casting
US5603860A (en) * 1994-07-25 1997-02-18 Voest-Alpine Industrieanlagenbau Gmbh Immersed casting tube
US5645121A (en) * 1996-01-05 1997-07-08 National Steel Corporation Method of continuous casting using sealed tundish and improved tundish seal
US5811023A (en) * 1995-07-27 1998-09-22 Voest-Alpine Industrieanlagenbau Gmbh Molten metal continuous casting process
US8523977B2 (en) 2011-01-14 2013-09-03 Nucor Corporation Method of desulfurizing steel

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE404497B (sv) * 1977-06-08 1978-10-09 Sven Forfarande for att gjuta en metallsmelta till got eller amnen
JPS59107754A (ja) * 1982-12-10 1984-06-22 Nippon Steel Corp アルミキルド鋼の連続鋳造法
FR2700283B1 (fr) * 1993-01-12 1995-02-10 Lorraine Laminage Busette immergée pour la coulée continue des métaux.
FR2740367B1 (fr) * 1995-10-30 1997-11-28 Usinor Sacilor Busette pour l'introduction d'un metal liquide dans une lingotiere de coulee continue de produits metalliques, dont le fond comporte des orifices
CN112191817B (zh) * 2020-09-11 2021-09-07 柳州钢铁股份有限公司 双流板坯连铸机在浇注中安全停流的方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3200457A (en) * 1964-03-09 1965-08-17 United States Steel Corp Method of regulating the discharge of molten metal from ladles
US3578064A (en) * 1968-11-26 1971-05-11 Inland Steel Co Continuous casting apparatus
US3608621A (en) * 1969-04-29 1971-09-28 Schloemann Ag Continuous casting apparatus with controlled overflow casting tube in tundish
US3738419A (en) * 1971-08-26 1973-06-12 Phelps Dodge Copper Prod Molten metal level control for continuous casting
US3833047A (en) * 1971-11-13 1974-09-03 Dalmine Spa Process and apparatus for supplementary cooling of the center of a continuously cast metal bar

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1542950A (fr) * 1966-10-18 1968-10-18 Metacon Ag Dispositif de coulée
FR1550283A (sv) * 1967-10-30 1968-12-20
ZA723617B (en) * 1971-05-28 1973-03-28 Rheinstahl Huettenwerke Ag A method of treating metal melts during the process of continuous casting and apparatus for performing the same

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3200457A (en) * 1964-03-09 1965-08-17 United States Steel Corp Method of regulating the discharge of molten metal from ladles
US3578064A (en) * 1968-11-26 1971-05-11 Inland Steel Co Continuous casting apparatus
US3608621A (en) * 1969-04-29 1971-09-28 Schloemann Ag Continuous casting apparatus with controlled overflow casting tube in tundish
US3738419A (en) * 1971-08-26 1973-06-12 Phelps Dodge Copper Prod Molten metal level control for continuous casting
US3833047A (en) * 1971-11-13 1974-09-03 Dalmine Spa Process and apparatus for supplementary cooling of the center of a continuously cast metal bar

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3935895A (en) * 1973-06-14 1976-02-03 Vereinigte Osterreichische Eisen- Und Stahlwerke-Alpine Montan Aktiengesellschaft Continuous steel casting method
US3931850A (en) * 1974-03-11 1976-01-13 Mannesmann Aktiengesellschaft Apparatus for feeding and distributing steel melts
US3991815A (en) * 1974-06-25 1976-11-16 Vereinigte Osterreichische Eisen- Und Stahlwerke-Alpine Montan Aktiengesellschaft Casting tube with a bottom opening for continuously casting steel strands
US4015655A (en) * 1974-06-25 1977-04-05 Vereinigte Osterreichische Eisen- Und Stahlwerke-Alpine Montan Aktiengesellschaft Process and apparatus for continuously casting strands of unkilled or semi-killed steel
US3996994A (en) * 1974-09-02 1976-12-14 Mannesmann Aktiengesellschaft Supplying molten metal to a mold for continuous casting
US4064925A (en) * 1975-02-25 1977-12-27 Vereinigte Osterreichische Eisen- Und Stahlwerke-Alpine Montan Aktiengesellschaft Continuous casting method and apparatus
US4520861A (en) * 1983-11-18 1985-06-04 Republic Steel Corporation Method and apparatus for alloying continuously cast steel products
US5205343A (en) * 1989-06-03 1993-04-27 Sms Schloemann-Siemag Aktiengesellschaft Pouring tube for feeding molten steel into a continuous casting mold
EP0648561A1 (en) * 1993-10-13 1995-04-19 Nkk Corporation Immersion nozzle for continuous casting
US5501430A (en) * 1993-10-13 1996-03-26 Nkk Corporation Immersion nozzle for continuous casting
US5603860A (en) * 1994-07-25 1997-02-18 Voest-Alpine Industrieanlagenbau Gmbh Immersed casting tube
US5811023A (en) * 1995-07-27 1998-09-22 Voest-Alpine Industrieanlagenbau Gmbh Molten metal continuous casting process
US5894880A (en) * 1995-07-27 1999-04-20 Voest-Alpine Industrieanlagenbau Gmbh Molten metal continuous casting process
US5645121A (en) * 1996-01-05 1997-07-08 National Steel Corporation Method of continuous casting using sealed tundish and improved tundish seal
US8523977B2 (en) 2011-01-14 2013-09-03 Nucor Corporation Method of desulfurizing steel

Also Published As

Publication number Publication date
IT1005964B (it) 1976-09-30
FR2233121A1 (sv) 1975-01-10
SE7404552L (sv) 1974-12-16
BE814094A (fr) 1974-08-16
AT331438B (de) 1976-08-25
GB1472576A (en) 1977-05-04
CH575264A5 (sv) 1976-05-14
ATA522373A (de) 1975-11-15
ES425951A1 (es) 1976-07-01
BR7404816D0 (pt) 1975-01-07
FR2233121B1 (sv) 1978-01-20
DE2428059A1 (de) 1975-01-09
CA1022323A (en) 1977-12-13
JPS5022719A (sv) 1975-03-11

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