US3773496A - Process for producing chrome steels and a converter for carrying out the process - Google Patents

Process for producing chrome steels and a converter for carrying out the process Download PDF

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Publication number
US3773496A
US3773496A US00116447A US3773496DA US3773496A US 3773496 A US3773496 A US 3773496A US 00116447 A US00116447 A US 00116447A US 3773496D A US3773496D A US 3773496DA US 3773496 A US3773496 A US 3773496A
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United States
Prior art keywords
oxygen
melt
nitrogen
inert gas
blowing
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Expired - Lifetime
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US00116447A
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English (en)
Inventor
H Knuppel
K Brotzmann
H Fassbinder
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Eisenwerke Gesellschaf Maximilianshuette mbH
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Eisenwerke Gesellschaf Maximilianshuette mbH
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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
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/005—Manufacture of stainless steel
    • 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
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/30—Regulating or controlling the blowing
    • C21C5/34—Blowing through the bath
    • 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
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/42—Constructional features of converters
    • C21C5/46—Details or accessories
    • C21C5/48—Bottoms or tuyéres of converters
    • 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

Definitions

  • PROCESS FOR PRODUCING CHROME STEELS AND A CONVERTER FOR CARRYING OUT THE PROCESS [75] Inventors: Helmut Knuppel; Karl Brotzmann;
  • the application also discloses a novel bottom-blown converter construction for carrying out the refining procedure.
  • the invention is particularly applicable to the production of ferritic chrome steels of the indicated kind and will thus, in the following, primarily be described inconnection with ferritic chrome steels, the invention can also be used for the production of austenitic steels.
  • Ferritic chrome steels having a chromium content of between 30% and extremely low carbon and nitrogen contents exhibit superior forming properties and ductility. Further, such steels have excellent corrosion resistance and exhibit superior weldability, particularly if the steels are alloyed with molybdenum. In order to obtain steels with the indicated characteristics, the sum total of the carbon and nitrogen contents should be below 0.015% or should at least not exceed that value to any significant extent.
  • the increase in nitrogen is also due to the fact that the oxygen jet or stream which emanatesfrom the blowing or jetting lance at high speed results in a suction action, so that air or atmospheric nitrogen is sucked into the converter, thus introducing more nitrogen into the melt.
  • Austrian Pat. No; 150,979 discloses, for example, a process for decarburizing ferro-chrome melts wherein a chromium containing melt of a carbon content of about 1% is charged into a vacuum reactor and isrefined-with pure oxygen or a refining gas containing a high percentage of oxygen. Due to the displacement of the carbon-oxygen equilibrium in the vacuum, this procedure results in a reduction of the chromium losses caused by chromium oxidation. However, the necessary. extremely low carbonzcontent required in ferritic chrome steels cannot be obtained. Furthermore, in this prior art procedure no measures are taken to prevent nitrogen pickup by the melt.
  • a further process for decarburizing steel melts containing about 3-30% chromium is disclosed in U.S. Pat. No. 3,046,107.
  • This process suggests that a decreasing amount of oxygen is introduced into the melt together with an inert gas at temperatures of about 1 ,4001,900C.
  • the purpose of the introduction of the oxygen and the inert gas is to reduce the chromium loss and to achieve a final carbon content of 0.07%.
  • this process does not consider the nitrogen content of the steel, and the starting point for the process is a remelt or steel charge.
  • the nitrogen content of the customary chrome steels usually is between 0.02 and 0.085%.
  • a chrome steel containing 9-1 1% of chromium, 2-8% of manganese, and l-5% of nickel may customarily contain 0.07-0.08% nitrogen.
  • the solution of the inventive tasks is based on the realiziation that the desired low nitrogen content can be obtained in an economically feasible manner if the composition of the starting melt is chosen such, and the refining procedure is controlled in such a manner, that already during the decarburization with pure oxygen the nitrogen content of the melt is decreased to an extent which is far greater than the customary nitrogen removal which occurs as the result of blowing of pure oxygen.
  • the invention provides that a pig iron or hot metal charge having a high chromium content and a carbon content of about 2-7% is refined under reduced pressure conditions by blowing very pure oxygen below the level of the melt.
  • the success of the inventive procedure is based on the fact that, due to the blowing with very pure oxygen under reduced pressure conditions, a very rapid decarburization is obtained resulting in a carbon content of extremely low values wile, at the same time, nitrogen pickup from the refining gas and/or the ambient atmosphere is successfully prevented.
  • the carbon content of the starting melt is advantageously made dependent on the nitrogen content of the starting melt.
  • the carbon content should initially be about 6 percent.
  • the pressure above the melt during the refining should be the lower the lower the carbon content is of the original charge.
  • the ratio of initial carbon contentto absolute pressure which is 60 in the above example always be maintained. It is therefore recommended, considering an economical performance of the procedure, to start with a relatively high initial carbon content.
  • the refining is advantageously performed with oxygen ofa purity degree of 99.9% which, in addition to noble gases, may possibly contain not more than ppm of nitrogen.
  • the purity of the argon should be at least 99.95 and preferably 99.99 percent.
  • the carbon content in spite of the high initial value, may be lowered to 0.5% while the nitrogen content is at the same time decreased from about 0.035 to 0.010%.
  • the additional refining is advantageously performed with a mixture of oxygen and an inert gas which is essentially free of nitrogen.
  • inert gas may, for example, be argon and/or hydrogen which facilitates the formation of CO bubbles in the melt.
  • the proportion of inert gas in the oxygen may be gradually increased until the inert gas, at the end stage of the blowing, amounts to l00%.
  • the inventive procedure may be carried out particularly economically and advantageously in a bottom blown converter.
  • FIGURE of the drawings indicates a sectional view of a preferred embodiment of a converter suitable for carrying out the inventive procedure.
  • the converter shown therein consists of a steel shell 3 which is lined with a refractory lining 4.
  • a bottom plate 5 is provided which supports the removable tuyere bottom 6.
  • One half of the bottom 6, the lefthand side in the drawing, is traversed by a plurality of tuyeres or nozzles 7.
  • Each nozzle consists of an inner tube 9 and an outer tube 11, the inner tubes 9 being all connected to a common oxygen line 8, while all the outer tubes 11 are connected to a common inert gas conduit or line 10. It will be noted that the nozzles or tuyeres are inclined relative to the longitudinal axis of the converter.
  • the mouth 12 of the converter is relatively small and is situated within a hood 13 which is placed on the converter and connected therewith in gas-tight manner.
  • the hood is provided with a vacuum tube 14 and communicates with a container 15 for receiving the alloying ingredients which, after opening of the slide valve 16, are charged from the container 15, without pressure decrease, into the converter.
  • the container 15 with the slide 16 thus acts as a vacuum lock or sluice and the detachable hood 13 is connected with the converter shell in vacuum-tight manner.
  • the converter shell 3 is preferably welded in vacuum-tight manner.
  • the converter is provided with a pouring hole 17 which, during the refining procedure, is closed by means of a closure or cap 18 in gas-tight manner.
  • the converter here shown and particularly suitable for the inventive procedure is shaped approximating that of a sphere or ball. Such sphere-like converters are more suitable for the present invention.
  • the filling degree of the converter should be lower than in the customary procedures.
  • a converter to be used for refining a 20-ton charge in accordance with the inventive procedure should have about twice the volume, to wit, about 30 m. It is also important that the leak losses caused by uptight areas should not exceed 0.01 percent of the off-gases which are sucked off through the vacuum pipe 14.
  • the melt could be replenished with about 4% of chrome ore, calculated on the weight of the rrielt. This was done by opening the slide 16 so that the chrome ore dropped into the converter from the'container 15. The carbon removal and nitrogen removal was then continued by blowing an oxygen-argon mixture. During a further blowing period of 20 min., the argon portion which originally was when the car bon content was 0.5%, was gradually increased to 95%, while the carbon content in the melt decreased to 0.005%, and the pressure in the final phase of the refining was lowered to l0-2O mmHg. The propane supply was interrupted when the argon moiety of the blowing gas amounted to 50 percent and instead pure argon was used as shell gas.
  • the starting chromium content of the melt may be lower than would be required in the light of the desired final chromium content. This is so because the high blowing temperature at the end of the first blowing stage renders it possible to add significant amounts of chromium ore at that time. Considering the significant increase of the solubility of nitrogen with increasing chromium content, the initial relatively low chromium content results correspondingly in a lower initial nitrogen content of the charge to be refined. In order to expedite and accelerate the reduction of the chromium ore, silicon and/or aluminum may at the same time be added. to the converter as reduction agent.
  • the refining gas and/or the mixture of refining gas and inert gas may be admixed with lime in powder form.
  • This general advantage has a particularly favorable effect in the inventive converter construction since the problems caused by the sealing of the structure can be more readily solved.
  • due to the addition of lime a satisfactory and early phosphorus and sulfur removal takes place. Accordingly, it is then also possible to use less expensive starting materials. If the initial phosphorus and sulfur contents are high, it may be required to operate with two slags. In experimental melts, the first slag was removed after about 3-10 min. and the refining procedure corresponding to the above example was continued and terminated under a second slag.
  • the invention is particularly suitable for the production of ferritic steels.
  • austenitic steels may also produced in accordance with the inventive procedure and in the inventive converter structure.
  • the requirements of the individual process steps need not be exactly adhered to.
  • it is sufficient if the pressure above the melt is in a range of l-0.3 atm.
  • the admixture of inert gas during the refining process may be increased toward the end of the procedure up to percent.
  • molten pig iron charge having a high chromium content and an initial carbon content of about between 27% by introducing at least one stream of pure oxygen through at least one injector extending through the refractory lining of said vessel and having an opening communicating with the interior of the vessel below the surface of the molten charge and terminating at the exposed surface of the refractory lining;
  • blowing of the oxygen is effected, at least during a portion of the blowing procedure, in admixture with an inert gas, the amount of inert gas gradually increasing in the mixture until it has reached a value of about -100 percent in the final stages of the refining procedure.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Carbon Steel Or Casting Steel Manufacturing (AREA)
US00116447A 1970-02-18 1971-02-18 Process for producing chrome steels and a converter for carrying out the process Expired - Lifetime US3773496A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19702007373 DE2007373B2 (de) 1970-02-18 1970-02-18 Verfahren und konverter zum herstellen ferritischer chromstaehle

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US00303161A Expired - Lifetime US3796421A (en) 1970-02-18 1972-11-02 Process for producing chrome steels and a converter for carrying out the process

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US (2) US3773496A (https=)
JP (1) JPS4942201B1 (https=)
DE (1) DE2007373B2 (https=)
FR (1) FR2130796A5 (https=)
GB (2) GB1331564A (https=)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3909245A (en) * 1973-03-30 1975-09-30 Maximilianshuette Eisenwerk Process for lowering the iron content in nickel melts
US3929458A (en) * 1973-02-07 1975-12-30 Creusot Loire Process for the elaboration of chrome steels
US3976473A (en) * 1973-12-31 1976-08-24 Nippon Steel Corporation Method for producing an extremely low carbon and nitrogen steel in a vacuum refining apparatus
US4001012A (en) * 1973-11-28 1977-01-04 United States Steel Corporation Method of producing stainless steel
US4139370A (en) * 1972-01-13 1979-02-13 Gesellschaft Fur Elektrometallurgie Mbh Method of refining ferro-alloys
US4154602A (en) * 1977-01-31 1979-05-15 Kawasaki Steel Corporation Method of denitriding a high chromium molten steel with a minimum chromium loss
US4170467A (en) * 1977-01-31 1979-10-09 Kawasaki Steel Corporation Method for producing high chromium steels having extremely low carbon and nitrogen contents
US4174212A (en) * 1978-03-10 1979-11-13 A. Finkl & Sons Co. Method for the refining of steel
US4783219A (en) * 1985-11-13 1988-11-08 Nippon Kokan Kabushiki Kaisha Method for melting and reducing chrome ore
US4792352A (en) * 1986-01-20 1988-12-20 Nippon Kokan Kabushiki Kaisha Method for manufacturing steel through smelting reduction
RU2150513C1 (ru) * 1998-11-02 2000-06-10 ОАО Челябинский металлургический комбинат "МЕЧЕЛ" Способ продувки высокохромистых сталей (процесс "мечел")
RU2268948C2 (ru) * 2004-03-02 2006-01-27 ОАО Челябинский металлургический комбинат "МЕЧЕЛ" Способ продувки высокохромистых сталей
RU2797319C1 (ru) * 2022-10-07 2023-06-02 Федеральное государственное бюджетное учреждение науки Институт металлургии и материаловедения им. А.А. Байкова Российской академии наук (ИМЕТ РАН) Способ выплавки коррозионностойкой стали в электродуговой сталеплавильной печи постоянного тока с полым графитовым электродом

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2243839A1 (de) * 1972-09-07 1974-03-28 Kloeckner Werke Ag Verfahren zur herstellung kohlenstoffarmer hochchromhaltiger ferritischer staehle
FR2202162A1 (en) * 1972-10-06 1974-05-03 Uddeholms Ab Decarburising converter linings wear reduction - for decarburising molten masses with high chrome contents, esp. stainless steel
SE371211B (https=) * 1973-03-12 1974-11-11 Uddeholms Ab
US3854932A (en) * 1973-06-18 1974-12-17 Allegheny Ludlum Ind Inc Process for production of stainless steel
DE2538159C2 (de) * 1974-08-30 1984-08-09 USS Engineers and Consultants, Inc., Pittsburgh, Pa. Verfahren zum Frischen von Roheisen
FR2357648A1 (fr) * 1976-07-09 1978-02-03 Creusot Loire Convertisseur rotatif a chauffage et soufflage simultanes
FR2364975A1 (fr) * 1976-09-20 1978-04-14 Siderurgie Fse Inst Rech Procede d'elaboration, au convertisseur, d'acier inoxydable
DE2821379A1 (de) * 1978-05-16 1979-11-22 Baum Verfahrenstechnik Vorrichtung zum auffangen von konverterabgasen
EP0104841B1 (en) * 1982-09-23 1986-07-30 National Research Development Corporation Removing phosphorous from iron
CH668925A5 (de) * 1985-12-31 1989-02-15 Fischer Ag Georg Behandlungsgefaess zur behandlung von fluessigen metall-legierungen.
EP4328330A4 (en) * 2021-05-26 2024-10-30 JFE Steel Corporation Method for refining molten iron

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US2068785A (en) * 1933-11-20 1937-01-26 United States Steel Corp Method of manufacturing low carbon steel
US2093666A (en) * 1934-11-23 1937-09-21 Wacker Chemie Gmbh Process for treating iron and iron alloys
US2855293A (en) * 1955-03-21 1958-10-07 Air Liquide Method and apparatus for treating molten metal with oxygen
GB861238A (en) * 1958-02-03 1961-02-15 Arbed Process for making steel
GB882676A (en) * 1958-01-29 1961-11-15 British Oxygen Co Ltd Treatment of ferrous material
US3198624A (en) * 1961-08-24 1965-08-03 Interlake Steel Corp Process for the manufacture of stainless steel
US3252790A (en) * 1956-06-27 1966-05-24 Union Carbide Corp Preparation of metals and alloys
FR1450718A (fr) * 1965-07-12 1966-06-24 Air Liquide Perfectionnements à des procédés métallurgiques
US3282679A (en) * 1962-09-18 1966-11-01 Gussstahlwerk Witten Ag Production of alloy steel
US3336132A (en) * 1964-03-09 1967-08-15 Crucible Steel Co America Stainless steel manufacturing process and equipment
US3420657A (en) * 1966-02-14 1969-01-07 Union Carbide Corp Oxygen treatment of chromium alloys
US3507642A (en) * 1969-06-02 1970-04-21 Allegheny Ludlum Steel Process for producing corrosion resistant steel
US3594155A (en) * 1968-10-30 1971-07-20 Allegheny Ludlum Steel Method for dynamically controlling decarburization of steel

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US84336A (en) * 1868-11-24 John abstee
US2182064A (en) * 1935-10-31 1939-12-05 Wacker Chemie Gmbh Apparatus for treating matters in hot liquid state
US2265511A (en) * 1937-12-08 1941-12-09 Brassert & Co Bessemer converter
AT222377B (de) * 1959-10-13 1962-07-25 Balzers Hochvakuum Ofen zum Behandeln von Metallschmelzen in Vakuum oder in Schutzgasatmosphäre
NL296346A (https=) * 1962-08-07
US3325160A (en) * 1963-03-06 1967-06-13 Asea Ab Vacuum-enclosed tiltable furnace
DE1433443B2 (de) * 1964-05-23 1972-01-27 Fried Krupp GmbH, 4300 Essen Verfahren zur ueberwachung und regelung der sauerstoffauf blasverfahren
US3501290A (en) * 1966-08-29 1970-03-17 Finkl & Sons Co Method of treating molten metal with arc heat and vacuum
GB1253581A (en) * 1968-02-24 1971-11-17 Maximilianshuette Eisenwerk Improvements in processes and apparatus for making steel

Patent Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2068785A (en) * 1933-11-20 1937-01-26 United States Steel Corp Method of manufacturing low carbon steel
US2093666A (en) * 1934-11-23 1937-09-21 Wacker Chemie Gmbh Process for treating iron and iron alloys
US2855293A (en) * 1955-03-21 1958-10-07 Air Liquide Method and apparatus for treating molten metal with oxygen
US3252790A (en) * 1956-06-27 1966-05-24 Union Carbide Corp Preparation of metals and alloys
GB882676A (en) * 1958-01-29 1961-11-15 British Oxygen Co Ltd Treatment of ferrous material
GB861238A (en) * 1958-02-03 1961-02-15 Arbed Process for making steel
US3198624A (en) * 1961-08-24 1965-08-03 Interlake Steel Corp Process for the manufacture of stainless steel
US3282679A (en) * 1962-09-18 1966-11-01 Gussstahlwerk Witten Ag Production of alloy steel
US3336132A (en) * 1964-03-09 1967-08-15 Crucible Steel Co America Stainless steel manufacturing process and equipment
FR1450718A (fr) * 1965-07-12 1966-06-24 Air Liquide Perfectionnements à des procédés métallurgiques
US3420657A (en) * 1966-02-14 1969-01-07 Union Carbide Corp Oxygen treatment of chromium alloys
US3594155A (en) * 1968-10-30 1971-07-20 Allegheny Ludlum Steel Method for dynamically controlling decarburization of steel
US3507642A (en) * 1969-06-02 1970-04-21 Allegheny Ludlum Steel Process for producing corrosion resistant steel

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4139370A (en) * 1972-01-13 1979-02-13 Gesellschaft Fur Elektrometallurgie Mbh Method of refining ferro-alloys
US3929458A (en) * 1973-02-07 1975-12-30 Creusot Loire Process for the elaboration of chrome steels
US3909245A (en) * 1973-03-30 1975-09-30 Maximilianshuette Eisenwerk Process for lowering the iron content in nickel melts
US4001012A (en) * 1973-11-28 1977-01-04 United States Steel Corporation Method of producing stainless steel
US3976473A (en) * 1973-12-31 1976-08-24 Nippon Steel Corporation Method for producing an extremely low carbon and nitrogen steel in a vacuum refining apparatus
US4170467A (en) * 1977-01-31 1979-10-09 Kawasaki Steel Corporation Method for producing high chromium steels having extremely low carbon and nitrogen contents
US4154602A (en) * 1977-01-31 1979-05-15 Kawasaki Steel Corporation Method of denitriding a high chromium molten steel with a minimum chromium loss
US4174212A (en) * 1978-03-10 1979-11-13 A. Finkl & Sons Co. Method for the refining of steel
US4783219A (en) * 1985-11-13 1988-11-08 Nippon Kokan Kabushiki Kaisha Method for melting and reducing chrome ore
EP0222397A3 (en) * 1985-11-13 1989-06-07 Nippon Kokan Kabushiki Kaisha Method for melting and reducing chrome ore method for melting and reducing chrome ore
US4792352A (en) * 1986-01-20 1988-12-20 Nippon Kokan Kabushiki Kaisha Method for manufacturing steel through smelting reduction
RU2150513C1 (ru) * 1998-11-02 2000-06-10 ОАО Челябинский металлургический комбинат "МЕЧЕЛ" Способ продувки высокохромистых сталей (процесс "мечел")
RU2268948C2 (ru) * 2004-03-02 2006-01-27 ОАО Челябинский металлургический комбинат "МЕЧЕЛ" Способ продувки высокохромистых сталей
RU2797319C1 (ru) * 2022-10-07 2023-06-02 Федеральное государственное бюджетное учреждение науки Институт металлургии и материаловедения им. А.А. Байкова Российской академии наук (ИМЕТ РАН) Способ выплавки коррозионностойкой стали в электродуговой сталеплавильной печи постоянного тока с полым графитовым электродом

Also Published As

Publication number Publication date
FR2130796A5 (https=) 1972-11-10
JPS4942201B1 (https=) 1974-11-13
DE2007373B2 (de) 1973-05-03
DE2007373A1 (de) 1971-08-26
GB1331565A (en) 1973-09-26
US3796421A (en) 1974-03-12
GB1331564A (en) 1973-09-26

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