EP0151872B1 - Verfahren zur Vakuumbehandlung von Stahl - Google Patents

Verfahren zur Vakuumbehandlung von Stahl Download PDF

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Publication number
EP0151872B1
EP0151872B1 EP84308261A EP84308261A EP0151872B1 EP 0151872 B1 EP0151872 B1 EP 0151872B1 EP 84308261 A EP84308261 A EP 84308261A EP 84308261 A EP84308261 A EP 84308261A EP 0151872 B1 EP0151872 B1 EP 0151872B1
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EP
European Patent Office
Prior art keywords
tube
vacuum
rod
molten
bath
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.)
Expired
Application number
EP84308261A
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English (en)
French (fr)
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EP0151872A3 (en
EP0151872A2 (de
Inventor
Joseph Mulcahy
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.)
J Mulcahy Enterprises Inc
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J Mulcahy Enterprises Inc
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
Application filed by J Mulcahy Enterprises Inc filed Critical J Mulcahy Enterprises Inc
Priority to AT84308261T priority Critical patent/ATE39948T1/de
Publication of EP0151872A2 publication Critical patent/EP0151872A2/de
Publication of EP0151872A3 publication Critical patent/EP0151872A3/en
Application granted granted Critical
Publication of EP0151872B1 publication Critical patent/EP0151872B1/de
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/10—Handling in a vacuum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
    • C22B9/04—Refining by applying a vacuum

Definitions

  • the present invention relates to the processing of steels and other electroconductive metals.
  • dissolved gases including hydrogen, oxygen and nitrogen
  • metals for example, steels
  • metals for example, steels
  • metals for example, steels
  • the molten metal is housed in a large chamber and is agitated to facilitate removal of the gases by vacuum applied to the chamber.
  • This prior art operation is somewhat unsatisfactory, in that a molten metal to be treated must be tapped from a furnace with sufficient temperature to withstand heat losses during treatment, and efficient removal of the gas is not achieved.
  • a novel method and apparatus of degassing metals is provided (compare present claims 1 and 7). Particularly preferred embodiments of present invention are defined in the dependent claims 2 to 6 and 8 to 10.
  • the invention is particularly applicable to the treatment of molten steel and will be described mainly with reference thereto, but the invention is also applicable to any other electron- conductive metal.
  • molten steel is drawn from a bath into a vertical column by the vacuum, a high frequency coil . surrounds the vertical column and a high fre--quency alternating electrical current is passed - through the coil to provide an electrical field which compresses and contracts the vertical steel rod away from its confining walls.
  • the whole of the outer surface of the rod is exposed to vacuum and gas is drawn from the considerable surface area of the thin steel rod exposed to the vacuum.
  • the vacuum is then shut off, permitting the rod of degassed steel to return to the bath.
  • the process then is repeated until all the gases have been removed. While being subjected to vacuum, the molten steel column is also inductively superheated by the eddy currents induced in the molten steel.
  • the temperature at which the molten metal needs to be tapped from the furnace can be lower than in the prior art, typically about 1600°C for the present invention in comparison with about 1650°C for the prior art.
  • the high efficency of gas removal from the large surface area of the thin steel rod enables the dissolved gas content of the steel to be depleted to a very low level in a manageable number of passes.
  • a single treatment unit may be employed or a plurality of such treatment units may be used.
  • a steel-treating apparatus 10 comprises a pot 12 containing a bath 14 of molten stel to be treated.
  • the bath may be stirred by any convenient procedure, for example, argon gas stirring or electromagnetic stirring.
  • a vacuum application unit 16 is used to effect treatment of the steel.
  • the unit comprises a support member 18 which overlies the top of the pot 12 to enclose the molten steel bath 14.
  • a hollow tube 22 extends through the support member 18 and dips into the bath 14.
  • the tube 22 may be constructed of any convenient non-electrically-conducting and non-magnetic material, such as heat resistant refractory material.
  • the hollow tube at its upper end communicates with a vacuum line 24 whereby vacuum may be applied to the interior of the tube 22.
  • An electrical coil 26 is wound around the exterior of the tube 22 and is connected to a source of high frequency alternating current (not shown).
  • vacuum application unit 16 for treatment of the molten steel bath 14, a plurality of such units 16 may be employed, the number depending on the volume of molten steel to be treated.
  • vacuum is applied to the interior of the tube 22 by vacuum line 24, causing a rod of molten steel 28 to be drawn up into the hollow tube 22.
  • a high frequency alternating current preferably at a frequency of about 25 to about 50 kHz, is passed through the coil 26.
  • the resulting magnetic field establishes eddy currents in the molten steel red 28 which adds superheat and counteracts heat losses.
  • the eddy currents also result in a repellant magnetic field which causes ' the molten steel rod 28 to contract radially inwardly and to become detached from the inner wall of the tube 22, as shown in the detailed close up of Figure 2.
  • the molten steel rod 28 Since the molten steel rod 28 is detached from the inside wall of the tube 22, the whole of the exterior surface of the steel rod 28 over the length of the coil 26 is exposed to the vacuum applied by the vacuum tube 24.
  • the narrow diameter of the rod 28 and the large surface area of the rod which is exposed to the vacuum permit dissolved gases to be readily and substantially completely removed from the steel rod 28.
  • the vacuum is shut off, permitting the vacuum treated rod 28 to return to the bath 14.
  • the vacuum may be applied and released simultaneously to all or a selected number of the tubes 22 or may be applied and released sequentially to the tubes 22.
  • the vacuum may have any desired value to achieve the drawing of the steel rod 28 into the tube 22 and to withdraw the dissolved gases from the molten steel rod.
  • a vacuum of about 10 to about 300 torrs (about 13.3 to about 400 mbar) is used.
  • the number of cycles necessary to effect complete treatment depends on the overall volume of the molten metal, the diameter of the tube 22 and the value of the vacuum. Usually about 30 to 50 cycles is sufficient, with each cycle being about 30 to 60 seconds in duration.
  • the procedure of the invention enables dissolved gases to be removed from molten steel or other electroconductive metals efficiently and rapidly in an energy-efficient manner.
  • the present invention thereby overcomes the problems of prior art procedures for vacuum treating of such metals.
  • the present invention provides a novel method and apparatus for vacuum treating of steel or other electroconductive metal to remove dissolved gases therefrom, which involves exposure of a large surface area of narrow thickness of the molten metal to the action of vacuum while simultaneously heating the metal.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Superconductors And Manufacturing Methods Therefor (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Coating With Molten Metal (AREA)

Claims (10)

1. Verfahren zur Vakuumbehandlung einer Schmelze eines elektrisch leitenden Metalls wie beispielsweise Stahl, das darin besteht, daß ein Vakuum an ein Rohr gelegt wird, das taucht, um die Metallschmelze in das Rohr zu ziehen und einen langgesstreckten Stab der Metallschmelze im Rohr zu bilden, und daß der langgestreckte Stab elektromagnetisch radial nach innen zusammengedrückt wird, um den langgestreckten Stab von der Innenwand des Rohres zu lösen und die Außenfläche des elektromagnetisch zusammengedrückten Stabes dem Vakumm auszusetzen, damit dadurch gelöste Gase von dem Metallschmelzenstab abgezogen werden.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß das elektronmagnetische Zusammendrücken dadurch bewirkt wird, daß eine elektrische Spule um die Aussenfläche des Rohres herum ausgebildet und ein Wechselstrom mit hoher Frequenz durch die Spule geleitet wird.
3. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß a) vor dem anlegen des Vakumms das Stahleschmelzbad in einem Behälter vorgesehen wird und das Rohr in das Metallschmelzbad so eingeführt wird, daß es in das Metalischmelzbad eintaucht und davon im wesentlichen vertikal nach oben verläuft, und b) anschließend an das elektromagnetische Zusammendrücken des Metallschmelzenstabes und dann, wenn die Außenfläche des elektromagnetisch zusammengedrückten Stabes über ein gewünschtes Zeitintervall dem Vakuum ausgesetzt ist, das Vakuum vom Rohr abgenommen wird, damit der sich ergebende vakuumbehendelte Stab in das Schmelzbad zurückfallen kann.
4. Verfahren nach Anspruch 3, dadurch gekennzeichnet, daß es wiederholt in einer gewüschten Anzähl von Zyklen ausgeführt wird, um im wesentlichen vollständig die gelösten Gase von dem gesamten Metall im Schmelzbad abziehen zu können.
5. Verfahren nach Anspruch 4, dadurch gekennzeichnet, daß das Schmelzbad während der wiederholten Arbeitsvorgänge gerührt wird.
6. Verfahren nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß eine Vielzahl von Rohren in das Schmelzbad getaucht wird, en jedem von denen ein Vakuum angelegt wird, und der langgestreckte Stab in jedem Rohr elektromagnetisch zusemmengedrückt wird.
7. Vorrischtung zur Vakuumbehandlung eines elektrisch leitenden Metalls mit a) einem langgestreckten Rohr (22) aus einem warm-festen, elektrisch nicht leitenden und nicht magnetischen Material, das eine Innenbohrung aufweist und mit einem Ende in ein Schmelzbad (14) des zu behandelnden elektrisch leitenden Metalls getaucht werden kann, während das andere Ende an einer Vakuumkeitung (24) angebracht werden kann, um ein vakuum an die Bohrung zu legen b) einem Halteelement (18), durch das das Rohr (22) um eine Strecke vorsteht, die ausreicht, em es in das Bad (14) der Metallschmelze zu tauchen, wenn das Halteelement (18) mit einem Topf (12) in Eingriff kommt, der das Bad (14) der Metallschmelze enthält und neben einem Ende des Rohres (22) angeordnet ist, und c) einer elektrischen Spule (26), die um die Außenfläche des Rohres (22) im Bereich der Länge des Rohres (22) zwschen dem Halteelement (18) und dem anderen Ende des Rohres (22) gewickelt ist.
8. Vorrichtung nach Anspruch 7, gekennzeichnet durch Einrichtungen (24) zum Angelen eines Vakumms an die Bohrung am anderen Ende des Rohres (22).
9. Vorrichtung nach Aspruch 7 oder 8, gekennzeichnet durch Einrichtungen zum Leiten eines hochfrequenten Wechslestromes durch die elektrische Spule (26).
10. Vorrichtung nach einem der Anspüche 7 bis 9, dadurch gekennzeichnet, daß das Rohr (22) aus einem warm-festen, feuerfesten Material besteht.
EP84308261A 1984-01-20 1984-11-28 Verfahren zur Vakuumbehandlung von Stahl Expired EP0151872B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT84308261T ATE39948T1 (de) 1984-01-20 1984-11-28 Verfahren zur vakuumbehandlung von stahl.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CA000445735A CA1216430A (en) 1984-01-20 1984-01-20 Vacuum treating steels
CA445735 1984-01-20

Publications (3)

Publication Number Publication Date
EP0151872A2 EP0151872A2 (de) 1985-08-21
EP0151872A3 EP0151872A3 (en) 1986-06-25
EP0151872B1 true EP0151872B1 (de) 1989-01-11

Family

ID=4126993

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84308261A Expired EP0151872B1 (de) 1984-01-20 1984-11-28 Verfahren zur Vakuumbehandlung von Stahl

Country Status (5)

Country Link
EP (1) EP0151872B1 (de)
JP (1) JPS60159110A (de)
AT (1) ATE39948T1 (de)
CA (1) CA1216430A (de)
DE (1) DE3476086D1 (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2046149C1 (ru) * 1994-01-19 1995-10-20 Акционерное общество "Нижнетагильский металлургический комбинат" Способ вакуумного рафинирования металла и устройство для его осуществления

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT138020B (de) * 1933-07-19 1934-06-25 Berndorfer Metallwarenfabrik Verfahren und Vorrichtung, um Metallbäder zu entgasen.
DE1147714B (de) * 1957-08-01 1963-04-25 Vacuumschmelze Ag Vorrichtung und Verfahren zur Halterung und zum Transport elektrisch leitender, freischwebender Substanzen
DE1268790B (de) * 1961-08-09 1968-05-22 Erik Allan Olsson Verfahren zum fortlaufenden Entgasen von Metallschmelzen
US3347538A (en) * 1965-04-28 1967-10-17 Mc Graw Edison Co Apparatus for the vacuum degassing of molten metal
DE1508214A1 (de) * 1966-09-14 1970-03-05 Kloeckner Werke Ag Verfahren und Vorrichtung zum Entgasen von Metallschmelzen,insbesondere Stahlschmelzen,unter vermindertem Druck
US4298376A (en) * 1980-04-14 1981-11-03 Kobe Steel, Ltd. Method for treating molten steel and apparatus therefor

Also Published As

Publication number Publication date
JPH0142324B2 (de) 1989-09-12
CA1216430A (en) 1987-01-13
JPS60159110A (ja) 1985-08-20
DE3476086D1 (en) 1989-02-16
EP0151872A3 (en) 1986-06-25
ATE39948T1 (de) 1989-01-15
EP0151872A2 (de) 1985-08-21

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