US3871870A - Method of adding rare earth metals or their alloys into liquid steel - Google Patents

Method of adding rare earth metals or their alloys into liquid steel Download PDF

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Publication number
US3871870A
US3871870A US356087A US35608773A US3871870A US 3871870 A US3871870 A US 3871870A US 356087 A US356087 A US 356087A US 35608773 A US35608773 A US 35608773A US 3871870 A US3871870 A US 3871870A
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United States
Prior art keywords
steel
rare earth
earth metals
ladle
casting
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Expired - Lifetime
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US356087A
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English (en)
Inventor
Hidetaro Nemoto
Takaho Kawawa
Hideki Sato
Eiichi Sakamoto
Takayuki Koyano
Takanori Anzai
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JFE Engineering Corp
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Nippon Kokan Ltd
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Priority to US356087A priority Critical patent/US3871870A/en
Priority to DE2322604A priority patent/DE2322604C3/de
Priority to FR7316137A priority patent/FR2228111B1/fr
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Publication of US3871870A publication Critical patent/US3871870A/en
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    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21CPROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0056Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using cored wires
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22DCASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/10Supplying or treating molten metal
    • B22D11/11Treating the molten metal
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21CPROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04Removing impurities by adding a treating agent
    • C21C7/064Dephosphorising; Desulfurising

Definitions

  • ABSTRACT Primary Examiner-Walter R. Satterfield Attorney, Agent, or Firm-Moonray Kojima [57] ABSTRACT When one or more rare earth metals or their alloys are added into liquid steel in an intermediate vessel disposed between a-ladle and a mold, the resulting steel exhibits excellent impact property.
  • the MnS takes a comparatively round shape or of an eutectic crystal shape at the time of casting, but it is easily subjected to plastic formation during rolling. Thus, the resulting-product is elongated excessively in the rolling direction. Such phenomenon, as shown in FIG. 2, as explained further hereinbelow, cannot be eliminated simply by lowering the S content in steel.
  • S in the molten steel should not be precipitated as MnS at the time of solidification. That is to say, S content in some way should be fixed prior to its precipitation as MnS. If this can be done, then its concentration will not occur and prevention of segregation at the final stage of solidification will be facilitated.
  • This invention overcomes the aforementioned defects and problems, and advantageously enables increased productivity, lowering of manufacturing costs and production of an improved product.
  • the present invention enables desulphurization during ordinary casting and hence eliminates the prior art separate process of desulphurization.
  • the invention encompasses addition of rare earth metals or their alloys or mixtures thereof substantially into liquid steel at a location between a ladle and a mold.
  • the process is useful for continuous casting or other types of casting.
  • An object of the invention is to provide a desulphurization method in which it is possible to fix S of solute in steel prior to precipitation of ordinary MnS, and thus to prevent S center segregation.
  • Another object is to provide a desulphurization method which improves the impact properties in the transverse direction of a rolled steel.
  • FIG. 1 is a graph depicting the manner of concentration of solute element S
  • FIG. 2 is a graph depicting the relationship between S content in steel and its impact value
  • FIG. 3 depicts a diagrammatic view of an illustrative embodiment of the invention.
  • FIG. 4 is a graph depicting changes of Charpy impact value compared to Ce/S ratio.
  • the desulphurizing agent in the present invention desulphurizes and also plays an important part of fixing S content in steel before the S content is precipitated as MnS.
  • the term rare earth metal is well known in the art. Any rare earth metal and/or their alloys or mixtures thereof may be used in this invention. Examples thereof may be Lanthanum (La), Cerium (Ce), Presodimium (Pr), Neodymium (Nd) and others. Al-
  • loys of rare earth metals are often called misch metals.
  • Rare earth metals have an extremely Y strong affinity for oxygen, and hence, require extraordinary care for their use.
  • the degree anytype of care required for heir use is different from those required for ordinary and conventionally known desulphurizing agents such as calcium.
  • this is practically not feasible because of the strong affinity of rare earth metals with oxygen. Accordingly, optimum conditions for the location where the rare earth metal is added, the shape or form thereof, the rate of addition and amount thereof should be providedfor asdiscussed hereinbelow.
  • the rare earth metals, their alloys or mixtures thereof, may be added into liquid steel in a vessel which is disposed betweeen a ladle and a mold. Ordinarily, the liquid steel is poured directly from the ladle into the mold.
  • an intermediate vessel should be provided between the ladle and mold for addition of the rare earth metal to the liquid steel, in order to obtain highest yield of additives, to employ the purest steel available and to easily control additive amounts. If, for instance, the rare earth metals were to be added to the ladle, they would unavoidably react with the slag in the ladle either before or after pouring. The yieldwould then be unavoidably lowered due to oxidation.
  • Liquid steel to be poured to the vessel to which the rare earth metal is added should be substantially completely deoxidized for preferred effects. If there is any free oxygen remaining in the steel; for example Ce O C302 or C3203; La La added rare earth metal will tend to be wasted and lower the yield of desulphurization agent. For the same reason, rare earth metals to be added should be substantially completely sealed until they enter into the liquid molten steel. As will be described later, this can be easily done, for example, by such means as an immersion type nozzle using inert gasses. Rare earth metal to be added in this manner may preferably be in the form of a wire. Particle, granular or mass forms may be employed with desired effects.
  • the rare earth metal may be fed deeply into the liquid steel in the intermediate vessel under suitable conditions of shape, size and initial speed of addition. If the rare earth is in powder form, it has been found that such is difficult to feed deeply into the liquid steel.
  • the diameter of the metal particles, or other forms. should preferably be at least 2 mm or more in order to physically feed same into liquid steel with a suitable desired speed. A diameter of at least 2 mm or more is thus preferred as a minimum size. Any size above this may also be used.
  • the size may be selected dependent upon the amount to be added continuously corresponding to the casting speed. Such size, amount and speed can be readily calculated by the worker by observing such factors as rate of full utilization and entry into the liquid. A significant factor is the amount which is continuously added.
  • the amount depends upon the 5 content in the liquid steel to a large degree. However, a different type of care is required in continuous casting operation where one charge of molten metal is continuously case and drawn as a slab or predetermined dimensions.
  • the most suitable addition speed and hence amount corresponds to the casting speed in order to provide sufficient rare earth metals for reaction with the S content. if the amount to be added continuously was not suitable for the casting speed, then various defects, such as above mentioned become unavoidable.
  • Such an amount may be determined as just mentioned from the casting speed of the liquid steel which corresponds to the drawing speed of slab in known continuous casting processes.
  • the invention is not to be construed to be limited to speed, amount of addition, although such factors as size and speed are specific features of the invention.
  • the use of rare earth metals has heretofore not been known in the process of this application.
  • FIG. 3 shows one illustrative embodiment by which the invention process may be practiced.
  • One feature of the invention lies in arrangement of an intermediate vessel 2 between ladle 1 and mold 3.
  • First, tapped liquid steel from refining furnace (not shown) is substantially completely deoxidized by Al, Si and Mn in ladle 1. It is recommended that an inert gas such as N Ar and the like be blown through a nozzle (not shown) made of porous bricks or the like provided at the bottom part of ladle l for making clean molten steel and producing uniform temperature of the steel.
  • the liquid steel is then poured into an intermediate vessel, such as a tundish 2.
  • a teeming stream is prevent from airoxizing by an enclosing device .4.
  • Covering 12 on the bath surface is used to prevent oxidation of theliquid steel and to keep the temperature high.
  • Immersion type nozzle 13 is used for casting purposes.
  • a covering agent 14 is also used on the bath surface of casting mold 3.
  • the rare earth metal or alloy thereof may be fed deeply into the liquid steel by an arrangement such as shown in FIG. 3.
  • This arrangement comprises a hood 9, a feed ring 10 for inert gas feed, refractory pipe 11 immersed deeply into the liquid steel in vessel 2.
  • the added rare earth comprise a wire feeder 5, a reel 6 for the wire 7 which is shown being uncoiled and guide pipe 8 for the wire.
  • the arrangement for adding the rare earth metal to the liquid steel may be similarly constructed for metals having the form of particles, granules, or massive. The liquid steel is thus desulpherized efficiently without being subjected to air pollution and may hence be continuously finished as a product. It will be readily understood from the above that there are no factors present which would reduce the productivity.
  • the above combination i.e. a ladle, an intermediate vessel and a mold, may be most efficiently and effectively put into practice for known continuous casting processes.
  • the intermediate vessel may be a tundish of the process.
  • FIG. 4 shows the values as compared to that which has not been subjected to desulphurization with rare earth metals.
  • FIG. 4 is a graph showing the results of the above factory scale experiment in which the Ce/S ratio was varied, and the resulting impact values. Specifically, the results of V notch Charpy test at 0C and performed on a 9 mm thickness of plate are shown. According to this graph, there appears to be no significant difference in the rolling direction caused by addition of said rare earthmetal, but surprisingly, the impact value in the transverse direction is remarkably improved, in contrast to prior art steels, to'an extent thatCe/S isat its maximum value of about 1.5 (1.2 to 2.0). Such remarkable improvement is caused, it is thought, by no other reason than the S content in the steel being fixed as sultide with CeS, LaS or as compound sulfide thereof or as oxysulfide.
  • a wire such as above mentioned may be preferably effectively fed deeply into the liquid steel when the adding speed was 0.05 m/sec as above.
  • the rare earth metals or misch metals or any combination thereof may preferably be used in the present invention in the following ranges when used in the form of a wire: diameter: 2mm or above; adding speed: 0.05 m/sec. or above.
  • the inventors then performed an ultrasonic flaw detection test for cleanliness of the resulting steel and confirmed that there was no difference in the defective echos in the steel to which addition of rare earth metals had been made and in the steel to which no addition had been made. This confirmed that there was no deterioration of cleanliness of steel caused by the addition of rare earth metals or misch metals.
  • the present inventive process is also very effective in other casting processes.
  • the known bottom pouring process is one of the embodiments wherein the mold of the combination of ladle, intermediate vessel and mold may be replaced with a teeming pipe.
  • a rare earth metal selected from the group consisting of La, Ce, Pr and-Nd, any alloy thereof or any combination thereof, in the ratio of rare earth metal to sulfur of between 1.2 and 2.0 and in the form of a wire of a diameter of at least 2.0 to

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
US356087A 1973-05-01 1973-05-01 Method of adding rare earth metals or their alloys into liquid steel Expired - Lifetime US3871870A (en)

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US356087A US3871870A (en) 1973-05-01 1973-05-01 Method of adding rare earth metals or their alloys into liquid steel
DE2322604A DE2322604C3 (de) 1973-05-01 1973-05-04 Verfahren zum Entschwefeln von in der Pfanne vollständig desoxidiertem, flüssigen Stahl
FR7316137A FR2228111B1 (de) 1973-05-01 1973-05-04

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US356087A US3871870A (en) 1973-05-01 1973-05-01 Method of adding rare earth metals or their alloys into liquid steel
DE2322604A DE2322604C3 (de) 1973-05-01 1973-05-04 Verfahren zum Entschwefeln von in der Pfanne vollständig desoxidiertem, flüssigen Stahl
FR7316137A FR2228111B1 (de) 1973-05-01 1973-05-04

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4066248A (en) * 1976-02-27 1978-01-03 Fried. Krupp Gesellschaft Mit Beschrankter Haftung Charging device
US4088477A (en) * 1976-10-06 1978-05-09 Ford Motor Company Sheathless wire feeding of alloy and inoculant materials
US4290805A (en) * 1978-04-06 1981-09-22 Compagnie Universelle D'acetylene Et D'electro-Metallurgie Method for obtaining iron-based alloys allowing in particular their mechanical properties to be improved by the use of lanthanum, and iron-based alloys obtained by the said method
US4481032A (en) * 1983-08-12 1984-11-06 Pfizer Inc. Process for adding calcium to a bath of molten ferrous material
US4512800A (en) * 1983-08-12 1985-04-23 Pfizer Inc. Wire injection apparatus
US5291939A (en) * 1992-11-23 1994-03-08 Reynolds Metals Company Start-up method and apparatus for continuous casting of metal into strip product
US20040025980A1 (en) * 2000-05-26 2004-02-12 Karl Keller Method for producing spheroidal graphite cast iron
US20090057964A1 (en) * 2007-09-05 2009-03-05 Specialty Minerals (Michigan) Inc. Rotary lance
US20110030911A1 (en) * 2008-07-15 2011-02-10 Masafumi Miyazaki Low-carbon steel slab producing method
WO2018079887A1 (ko) * 2016-10-28 2018-05-03 한국생산기술연구원 편상 흑연 주철 및 주물과 그 제조방법

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3991810A (en) 1974-07-15 1976-11-16 Caterpillar Tractor Co. Method and apparatus for introducing additives into a casting mold
DE2636400A1 (de) * 1976-08-11 1978-02-16 Mannesmann Ag Verfahren zur verbesserung der kristallstruktur von im strang abgegossenem stahl
EP0185540A3 (de) * 1984-12-18 1987-05-27 Sumitomo Light Metal Industries Limited Verfahren zur Kornfeinung des primären Siliziums in hypereutektischen Al-Si-Legierungen
FR2680180B1 (fr) * 1991-08-09 1994-06-03 Peugeot Procede et dispositif d'introduction sous la forme d'un fil fusible, d'un additif de traitement dans un materiau liquide ou en fusion.

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2683661A (en) * 1951-10-31 1954-07-13 Molybdenum Corp Fine grain iron and method of production
US2823992A (en) * 1956-11-09 1958-02-18 American Metallurg Products Co Alloy steels
US2854716A (en) * 1955-04-07 1958-10-07 Alco Products Inc Method of adding lead to steel
US2980529A (en) * 1956-12-07 1961-04-18 American Metallurg Products Co Method of making aluminum killed steel
US3137753A (en) * 1959-06-30 1964-06-16 Fischer Ag Georg Device for treating metallic melts
US3313620A (en) * 1963-02-18 1967-04-11 E I Te R S P A Elettochimica I Steel with lead and rare earth metals
US3623862A (en) * 1968-06-24 1971-11-30 Int Harvester Co Use of rare earth elements for reducing nozzle deposits in the continuous casting of steel process
US3661537A (en) * 1969-07-16 1972-05-09 Jones & Laughlin Steel Corp Welded pipe structure of high strength low alloy steels
US3728109A (en) * 1969-10-04 1973-04-17 Nippon Kokan Kk Manufacturing method of free-cutting lead steel
US3768999A (en) * 1968-10-23 1973-10-30 Nippon Kokan Kk Coated wire feeding technique for making addition of components to molten metals

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE660069A (de) * 1964-02-25 1965-08-23

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2683661A (en) * 1951-10-31 1954-07-13 Molybdenum Corp Fine grain iron and method of production
US2854716A (en) * 1955-04-07 1958-10-07 Alco Products Inc Method of adding lead to steel
US2823992A (en) * 1956-11-09 1958-02-18 American Metallurg Products Co Alloy steels
US2980529A (en) * 1956-12-07 1961-04-18 American Metallurg Products Co Method of making aluminum killed steel
US3137753A (en) * 1959-06-30 1964-06-16 Fischer Ag Georg Device for treating metallic melts
US3313620A (en) * 1963-02-18 1967-04-11 E I Te R S P A Elettochimica I Steel with lead and rare earth metals
US3623862A (en) * 1968-06-24 1971-11-30 Int Harvester Co Use of rare earth elements for reducing nozzle deposits in the continuous casting of steel process
US3768999A (en) * 1968-10-23 1973-10-30 Nippon Kokan Kk Coated wire feeding technique for making addition of components to molten metals
US3661537A (en) * 1969-07-16 1972-05-09 Jones & Laughlin Steel Corp Welded pipe structure of high strength low alloy steels
US3728109A (en) * 1969-10-04 1973-04-17 Nippon Kokan Kk Manufacturing method of free-cutting lead steel

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4066248A (en) * 1976-02-27 1978-01-03 Fried. Krupp Gesellschaft Mit Beschrankter Haftung Charging device
US4088477A (en) * 1976-10-06 1978-05-09 Ford Motor Company Sheathless wire feeding of alloy and inoculant materials
US4290805A (en) * 1978-04-06 1981-09-22 Compagnie Universelle D'acetylene Et D'electro-Metallurgie Method for obtaining iron-based alloys allowing in particular their mechanical properties to be improved by the use of lanthanum, and iron-based alloys obtained by the said method
US4481032A (en) * 1983-08-12 1984-11-06 Pfizer Inc. Process for adding calcium to a bath of molten ferrous material
US4512800A (en) * 1983-08-12 1985-04-23 Pfizer Inc. Wire injection apparatus
US5291939A (en) * 1992-11-23 1994-03-08 Reynolds Metals Company Start-up method and apparatus for continuous casting of metal into strip product
US20040025980A1 (en) * 2000-05-26 2004-02-12 Karl Keller Method for producing spheroidal graphite cast iron
US20090057964A1 (en) * 2007-09-05 2009-03-05 Specialty Minerals (Michigan) Inc. Rotary lance
US7736415B2 (en) 2007-09-05 2010-06-15 Specialty Minerals (Michigan) Inc. Rotary lance
US20110030911A1 (en) * 2008-07-15 2011-02-10 Masafumi Miyazaki Low-carbon steel slab producing method
US9149867B2 (en) 2008-07-15 2015-10-06 Nippon Steel & Sumitomo Metal Corporation Low-carbon steel slab producing method
WO2018079887A1 (ko) * 2016-10-28 2018-05-03 한국생산기술연구원 편상 흑연 주철 및 주물과 그 제조방법

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DE2322604B2 (de) 1977-12-22
FR2228111A1 (de) 1974-11-29
DE2322604A1 (de) 1974-11-07
FR2228111B1 (de) 1975-12-26
DE2322604C3 (de) 1978-08-31

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