EP0240482A2 - Vorrichtung zum Giessen von Stahl - Google Patents

Vorrichtung zum Giessen von Stahl Download PDF

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Publication number
EP0240482A2
EP0240482A2 EP87870041A EP87870041A EP0240482A2 EP 0240482 A2 EP0240482 A2 EP 0240482A2 EP 87870041 A EP87870041 A EP 87870041A EP 87870041 A EP87870041 A EP 87870041A EP 0240482 A2 EP0240482 A2 EP 0240482A2
Authority
EP
European Patent Office
Prior art keywords
section
channel
steel
nozzle
final
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.)
Granted
Application number
EP87870041A
Other languages
English (en)
French (fr)
Other versions
EP0240482B1 (de
EP0240482A3 (en
Inventor
Stéphan Wilmotte
Raymond D'haeyer
Hubert Francois
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.)
Filing date
Publication date
Priority claimed from BE6/48215A external-priority patent/BE904545A/fr
Priority claimed from BE6/48253A external-priority patent/BE905256A/fr
Priority claimed from BE6/48278A external-priority patent/BE905968R/fr
Application filed by Centre de Recherches Metallurgiques CRM ASBL filed Critical Centre de Recherches Metallurgiques CRM ASBL
Priority to AT87870041T priority Critical patent/ATE56643T1/de
Publication of EP0240482A2 publication Critical patent/EP0240482A2/de
Publication of EP0240482A3 publication Critical patent/EP0240482A3/fr
Application granted granted Critical
Publication of EP0240482B1 publication Critical patent/EP0240482B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
    • B22D41/50—Pouring-nozzles
    • B22D41/58—Pouring-nozzles with gas injecting means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
    • B22D41/50—Pouring-nozzles
    • B22D41/62—Pouring-nozzles with stirring or vibrating means

Definitions

  • the present invention relates to a device for casting, in particular for the continuous casting of steel.
  • the liquid steel intended for casting is contained in a container such as a steel ladle or a distribution basket from which it is poured into the ingot mold through an orifice generally located in the bottom of the container.
  • This orifice is normally provided with a closure device making it possible to modify the steel flow rate and possibly to interrupt the casting.
  • the pouring orifice is constituted by a generally shaped part. tubular, called a nozzle; this tubular part, as well as the closure device which is associated with it, are generally made of a refractory material, in order to avoid any cooling of the steel which comes into contact with them.
  • the present invention provides a process for carrying out this pasty phase during the casting of steel.
  • the method of the present invention in which the steel is poured through a nozzle, is essentially characterized in that one causes a partial solidification of the peripheral layers of the steel in contact with the walls of the nozzle, and in that one creates within the steel in the nozzle sufficient agitation to suspend in the liquid steel steel particles from the peripheral layers being solidified.
  • the steel has a low overheating, that is to say less than 30 ° C, before entering the nozzle.
  • said partial solidification is caused by carrying out intense cooling of the walls of the nozzle.
  • agitation is created in the steel by means of a rotating electromagnetic field.
  • Such an electromagnetic field can be established by means of coils judiciously arranged around the steel vein.
  • the rotating electromagnetic field induces forces in the steel which create agitation and lead to the appearance of shear stresses, which give rise to high deformation rates in particular in the zone in the course of solidification.
  • This rotational movement of the steel in the nozzle can be further accentuated, in accordance with the invention, if an inert gas is injected into the steel in the vicinity of the entry of the steel into the nozzle. There is thus formed, at the inlet of the nozzle, a gas pocket which causes the formation of a vortex within the liquid steel.
  • this gas pocket extends into the nozzle itself.
  • the steel flowing through the nozzle is thus applied against the interior, cooled wall of the pouring channel, which promotes the cooling of its peripheral layers.
  • peripheral cooling and shearing thus causes the appearance of a pasty phase which retains good fluidity and which therefore does not disturb the flow of steel through the nozzle.
  • the proportion of the solid fraction which is thus suspended in the liquid steel can be adjusted, by varying the intensity of the cooling and the viscosity of the mixture by modifying at least one of the parameters of the rotating field. , for example its frequency or intensity, and / or the flow rate of said inert gas.
  • the direction of rotation of the vortex caused by said inert gas is preferably the same as the direction of rotation imparted by the rotating field.
  • Another object of the present invention is to provide a pouring nozzle which, thanks to its particular configuration and constitution, makes it possible to create conditions which lead to the appearance of a pasty phase in the steel, during its path between the ladle or the tundish on the one hand and the ingot mold on the other.
  • the pouring device of the nozzle type, which is the subject of the present invention is characterized in that it comprises a body in which is formed a liquid steel pouring channel, first means of cooling to ensure the cooling of said body as well as second stirring means to create agitation within the liquid steel located in said channel.
  • the inlet and outlet sections of said channel are of different dimensions, said outlet section being capable of ensuring the targeted steel flow taking into account the height of the charge of liquid steel at - above this section.
  • said channel may comprise at least two sections of different passage sections and, over at least part of its length, have a passage section greater than said outlet section.
  • said channel has a final section of short length, the section of which is constant and equal to said outlet section, an initial section of which the section is constant and greater than said outlet section, and an intermediate section connecting the initial section and the final section and the section of which varies continuously from the section of the initial section to the section of the final section.
  • the element in which said channel is formed advantageously consists of two parts, one part, said body of the nozzle having the initial section of said channel, and the other part, said head of the nozzle, presenting the intermediate section and the final section of said channel.
  • the inner surface of the nozzle carries inclined ribs, of short length, preferably arranged in the vicinity of the entrance to said channel.
  • FIG. 1 there is shown in 1 the channel of radius r through which the steel stream flows through the nozzle 2.
  • the reference numeral 3 denotes the conductors grouped in pairs (1 +, 1 -; 2 +, 2 -; 3 +, 3-) to constitute three inductors connected to the three phases of a three-phase current source not shown. The whole is joined by an envelope 4.
  • the steel vein flows through channel 1 perpendicular to the plane of the drawing, in the direction indicated by the arrow in the center.
  • the nozzle 2 is made of a material which is both a good conductor of heat, to facilitate the cooling of the steel, and electrically insulating, so as not to disturb the electromagnetic field.
  • a material based on boron nitride, silicon nitride or silicon carbide for example use a material based on boron nitride, silicon nitride or silicon carbide.
  • the conductors 3 consist of tubes made of a material which is a good conductor of heat and electricity, for example copper. They penetrate the thickness of the wall of the nozzle and they are traversed by water; they provide both intense cooling of the nozzle 2 and the application of the electromagnetic field.
  • the outer casing 4 is preferably made of a material which does not conduct electricity.
  • a cooling agent preferably gaseous, can be circulated in the channels between the outer casing 4, the conductors 3 and the nozzle 2.
  • a boron nitride nozzle having an internal radius r of 10 mm was used, while the radius R of the circumference tangent to the conductors 3 was equal to 15 mm.
  • the intensity of the induction at the level of the inductors was 20 mT and the current density at the periphery of the steel vein amounted to 12.5. 106 A / m2.
  • This same figure 2 also shows (ordinates - right axis) the evolution of the speed of deformation V d in steel along the radius r. This rate of deformation increases first very slightly from the center, then very suddenly in the zone being solidified. This growth in the rate of deformation causes the solidified layer to disintegrate as it is formed.
  • FIGS. 1 and 3 the nozzles are shown in their normal casting position, that is to say with the liquid steel flowing from top to bottom, and in FIGS. 1, 3 and 4, the same constituents are designated by the same reference numerals.
  • the nozzle shown schematically in Figure 3 consists of a nozzle body 2 and a nozzle head 5 which succeed one another without interruption in the direction of flow of the liquid steel. These two parts are fixed to each other by means not shown.
  • an initial section of diameter D1 of the pouring channel In the body of the nozzle 2 is formed an initial section of diameter D1, of the pouring channel, while the head of the nozzle 5 is provided with the final section, of diameter D6, and of the intermediate section, with a decreasing diameter of D1 to D6, of said sprue.
  • Tubular electrical conductors 3 are distributed over the periphery of the nozzle body 2; they are cooled by a circulation of water 6. These conductors 3 are further connected to an alternating current source, not shown.
  • the outer casing 4 ( Figure 1) is not shown here. These conductors 3 are intended on the one hand to inductively stir the steel present in the initial section of the pouring channel and on the other hand to cause, by cooling, a beginning of solidification of this steel, in particular in the close areas of the wall of the sprue.
  • the pouring channel has in its initial section a diameter D1 greater than the diameter D6 of the outlet section, the latter being determined so as to ensure the desired steel flow, taking into account the height of the load of liquid steel above the outlet section.
  • the nozzle conforms to the invention allows an accentuation on the one hand of the solidification of the steel under the action of the cooled conductors 3 and on the other hand of the rotational movement of the steel caused by the rotating electric field applied by the conductors 3.
  • FIG. 4 shows the peripheral distribution of the conductors 3 around the nozzle body 2, as well as their penetration into the thickness of this nozzle body 2.
  • the nozzle body 2 and the nozzle head 5 are advantageously made of different refractory materials adapted to the respective functions of these two parts.
  • the nozzle body is made of a material which is a good conductor of heat and a poor conductor of electricity, in order to ensure both the cooling of the steel and the electrical insulation of the conductors 3.
  • a material which is a good conductor of heat and a poor conductor of electricity in order to ensure both the cooling of the steel and the electrical insulation of the conductors 3.
  • a material having a high resistance to erosion in particular zirconium oxide.
  • the outlet section of the nozzle head 5, or its diameter is determined so as to ensure the flow of steel, that is to say say the desired casting speed (in t / h for example), taking into account the height of the liquid steel charge above this section.
  • An assimilation between the section and the diameter of the pouring channel is justified by the fact that this channel usually has a circular section.
  • the diameter of the initial section of the pouring channel, ie D1 should advantageously be between two and five times the diameter of the outlet section D6.
  • the final section of the pouring channel will have an axial length of between once and three times the diameter of the outlet section D6.
  • a length at least equal to the diameter is necessary to cancel the tangential component of the speed of flow of the steel. Beyond three times this diameter, an increase in this length does not bring any more improvement in this respect, it only results in an unnecessary increase in the price of the nozzle head.
  • a nozzle was produced in accordance with the invention, the body of which was made of a ceramic composed of boron nitride and silicon nitride, and the head of which was made of zirconium oxide.
  • the conductors 3 were copper tubes traversed by water circulating at high speed.
  • the steel had a carbon content of 0.7% and it showed 25 ° C overheating at the inlet of the nozzle.
  • the steel flow rate to be insured amounted to 20 t / h.
  • the three-phase inductor with a pair of poles was supplied with current having a frequency of 3000 Hz and an intensity per phase of 1550 A.
  • the magnetic induction at the level of the inductor was 20 mT.
  • the steel had an axial speed of 0.25 m / s and a tangential speed of 1.5 m / s.
  • the result was the possibility of removing a heat flux of 0.56 kW / m.
  • This speed increases rapidly and sharply in the vicinity of the cooled wall of the channel, that is to say in the zone where the cooling of the steel is most pronounced. It reflects the disintegration of the solidified steel layer, which thus retains sufficient fluidity for casting.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Continuous Casting (AREA)
EP19870870041 1986-04-02 1987-04-01 Vorrichtung zum Giessen von Stahl Expired - Lifetime EP0240482B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT87870041T ATE56643T1 (de) 1986-04-02 1987-04-01 Vorrichtung zum giessen von stahl.

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
BE6048215 1986-04-02
BE6/48215A BE904545A (fr) 1986-04-02 1986-04-02 Procede pour la coulee de l'acier.
BE6048253 1986-08-08
BE6/48253A BE905256A (fr) 1986-08-08 1986-08-08 Dispositif pour la coulee de l'acier.
BE6048278 1986-12-17
BE6/48278A BE905968R (fr) 1986-04-02 1986-12-17 Procede et dispositif pour la coulee de l'acier.

Publications (3)

Publication Number Publication Date
EP0240482A2 true EP0240482A2 (de) 1987-10-07
EP0240482A3 EP0240482A3 (en) 1988-01-13
EP0240482B1 EP0240482B1 (de) 1990-09-19

Family

ID=27159695

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19870870041 Expired - Lifetime EP0240482B1 (de) 1986-04-02 1987-04-01 Vorrichtung zum Giessen von Stahl

Country Status (1)

Country Link
EP (1) EP0240482B1 (de)

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB705762A (en) * 1951-10-15 1954-03-17 Skf Svenska Kullagerfab Ab Improvements relating to the continuous casting of metals
BE893168A (fr) * 1982-05-13 1982-11-16 Vesuvius Internat Corp Orifice d'injection d'un gaz de protection dans un tube de coulee
LU84617A1 (fr) * 1983-01-31 1984-10-24 Arbed Busettes pour lingotieres ainsi que leur utilisation
BE903805A (fr) * 1985-12-05 1986-06-05 Centre Rech Metallurgique Procede pour la coulee continue des metaux.

Also Published As

Publication number Publication date
EP0240482B1 (de) 1990-09-19
EP0240482A3 (en) 1988-01-13

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