US3907548A - Process for the production of steels having high chromium content and lowest possible carbon content - Google Patents

Process for the production of steels having high chromium content and lowest possible carbon content Download PDF

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Publication number
US3907548A
US3907548A US482958A US48295874A US3907548A US 3907548 A US3907548 A US 3907548A US 482958 A US482958 A US 482958A US 48295874 A US48295874 A US 48295874A US 3907548 A US3907548 A US 3907548A
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process according
molten steel
stream
reducing agent
steel
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Expired - Lifetime
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US482958A
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English (en)
Inventor
Eberhard Steinmetz
Jurgen Berve
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Fried Krupp Huettenwerke AG
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Fried Krupp Huettenwerke AG
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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
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/068—Decarburising
    • C21C7/0685—Decarburising 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
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/10—Handling in a vacuum

Definitions

  • This invention is directed to the production of steel as having high chromium content and lowest possible carbon content. More particularly, this invention is directed to a process for the removal of carbon, as carbon monoxide or carbon dioxide from liquid chromium-containing steels while retaining in such liquid steels the chromium therein. More especially, this invention is directed to a process for refining chromiumcontaining steels without loss of chromium as the oxide thereof. This invention is especially directed to a onestep process for the production of high chromiumcontaining steels characterized by low carbon content.
  • the present invention is based upon a surprising finding that an oxidizing and reduction function can be carried out virtually simultaneously and at points virtually adjacent to one another whereby the carbon content of the steel can be reduced to the lowest possible value without loss of chromium into a slag.
  • an unidirectionally flowing stream of an oxidizing substance as H O, CO pulverized NiO and, iron oxide especially oxygen or air is introduced into or onto a molten liquid chromium-containing steel.
  • a reducing agent as Fe- Si, Ca-Si, Si, Ca, Mg, more especially, aluminum.
  • the aluminum is introduced at a point downstream from the point at which the oxidizing stream first enters into or onto the liquid steel.
  • the reducing agent is introduced onto or into the unidirectionally flowing stream at a point at least 5 cm. and advantageously up to cm. from the point where the oxidizing stream first makes contact with the molten steel bath.
  • the unidirectionally flowing stream is caused by the action of the gaseous stream' effecting an impulse thereon.
  • the unidirectional bath circulation is also effected by injected substances contained in such stream.
  • One means for affecting unidirectional bath circulation is described in Austrian patent 225 212, the disclosure of which is hereby incorporated herein by reference. According to such patent tangentially directed nozzles are arranged in a refining vessel, distributed uniformly over the periphery. By the action of a gaseous stream flowing through such nozzles a helical bath circulation is effected. This procedure is employed to even out the refining procedure. The rotation of the bath leads to a more uniform and more intensive mixing, with a constant change at the boundary surface between the bath and slag.
  • the unidirectional bath circulation is necessary for the proper contacting of the bath initially with the oxidant and thereafter with the reducing agent.
  • the addition of oxygen is only within the unidirectionally flowing stream created within the bath and does not take place over a number of points within the entire area of the vessel.
  • the main bath circulation has to be produced about an imaginary horizontal axis.
  • the introduction of such a stream into the bath can take place at an angle inclined to the bath surface and/or through the bottom or the wall of the melting vessel below the bath surface. It is important that conditions are provided by the unidirectional bath circulation which allows the initial addition of oxidizing agent followed by theaddition of reducing agent at the same time but downstream thereof or within a separate region in the unidirectionally flowing stream.
  • the gases and other substances are advantageously injected into or onto the metal surface without the for mation of any droplets. It has been found that the formation of droplets during the introduction of the oxidizing stream adversely affects the chromium/carbon ratio. Droplet formation can be avoided bysuitable se' lection of the process parameters, the blowing pressure of the gaseous stream, the angle at which the stream is introduced in or onto the liquidsteel-and the shape diameter and relative spacing of the nozzles employed therefore. It is desired that special attention be given to the nozzle diameter. It has been found that noxxle diameters having a relatively large diameter can be beneficially employed to-limit the formation of droplets. This is owing to the fact that such large nozzle diameters provide a gentle gas stream.
  • the process of the present invention affects marked reduction in the carbon content by flushing out carbon monoxide.
  • Substances which give off gases or which gasify can also be blown in tothe molten steel for this purpose.
  • the amount of oxidizing substance introduced generally depends upon the' amount: of carbon being removed from the steel being treated.
  • the introduction of the oxidizing stream to effect unidirectional bath circulation can be accomplished employing gaseous oxygen alone or in admixture with inert gases such as argon.
  • gaseous oxygen alone or in admixture with inert gases such as argon.
  • air can be used as the gaseous medium.
  • gas-yielding solids especially those which simultaneously exert a flushing action with the possibility of gas separation.
  • Gaseous constituents liberated by the gas yieldin'g solids include water, carbon monoxide, especially when the gaseous stream contains calcium carbonate.
  • the unidirectional bath circulation is particularly advantageously effected by the use of electromagnetic or mechanical stirring mechanisms. In a desirable embodiment the process is conducted by the addition of components for liquefying the slag.
  • EXAMPLE 1 Into a liquid steel composition having the assay below there was introduced an oxidizing stream of oxygen through a nozzle inclined at the surface of the liquid steel. The process was conducted under vacuum conditions. The steel analyzed as follows:
  • a contact area the disclosed distance refers to the shortest distance between the rims of the contact area of oxygen and metal and the area of aluminum introduction. Preferably the distance is between 30 em up to 50 cm.
  • the invention bases upon the effect that the chromium oxide being just constituted and not yet being part of the slag phase resting on the metal surface, has a good and remarkable reactivity for the reduction. Therefore the immediate reduction leads to a high chromium recovery and therefore the proposed process is very economic.
  • a process according to claim 8 wherein said reducing agent is aluminum and the ratio of the addition of the calcium carbonate and 'aluminum are so matched ameter and spacing of the noz-zlesemployed to produce the unidirectionally flowing stream.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Carbon Steel Or Casting Steel Manufacturing (AREA)
US482958A 1973-07-04 1974-06-25 Process for the production of steels having high chromium content and lowest possible carbon content Expired - Lifetime US3907548A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2333937A DE2333937C2 (de) 1973-07-04 1973-07-04 Verfahren zur Herstellung hochchromhaltiger Stähle mit niedrigstem Kohlenstoffgehalt

Publications (1)

Publication Number Publication Date
US3907548A true US3907548A (en) 1975-09-23

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ID=5885874

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US482958A Expired - Lifetime US3907548A (en) 1973-07-04 1974-06-25 Process for the production of steels having high chromium content and lowest possible carbon content

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US (1) US3907548A (enExample)
JP (1) JPS5038617A (enExample)
AT (1) AT340975B (enExample)
BE (1) BE817256A (enExample)
CA (1) CA1015169A (enExample)
DE (1) DE2333937C2 (enExample)
DK (1) DK356774A (enExample)
FR (1) FR2236007B3 (enExample)
GB (1) GB1432290A (enExample)
IT (1) IT1015605B (enExample)
LU (1) LU70449A1 (enExample)
NL (1) NL7408838A (enExample)
SE (1) SE7408783L (enExample)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4481032A (en) * 1983-08-12 1984-11-06 Pfizer Inc. Process for adding calcium to a bath of molten ferrous material
US4518422A (en) * 1982-11-17 1985-05-21 Arbed S.A. Process and apparatus for refining steel in a metallurgical vessel

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5394214A (en) * 1977-01-31 1978-08-18 Kawasaki Steel Co Denitriding method of high chrome molten steel with small chrome loss
JPS60121211A (ja) * 1983-12-02 1985-06-28 Nippon Steel Corp 含クロム溶鋼の還元脱硫法
JPS62127417A (ja) * 1985-11-26 1987-06-09 Kawasaki Steel Corp 溶融金属の精錬方法
TWI452270B (zh) * 2011-10-21 2014-09-11 Univ Nat Central 量測裝置及其量測方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3003865A (en) * 1959-09-10 1961-10-10 Cameron Iron Works Inc Decarburizing process for alloy steels containing chromium
US3218157A (en) * 1961-10-16 1965-11-16 Oesterr Alpine Montan Process for the production of high alloyed steels
US3467167A (en) * 1966-09-19 1969-09-16 Kaiser Ind Corp Process for continuously casting oxidizable metals
US3725041A (en) * 1970-09-25 1973-04-03 Allegheny Ludlum Ind Inc Deoxidizing metal
US3751242A (en) * 1969-04-02 1973-08-07 Eisenwerk Gmbh Sulzbach Rosenb Process for making chrimium alloys

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3003865A (en) * 1959-09-10 1961-10-10 Cameron Iron Works Inc Decarburizing process for alloy steels containing chromium
US3218157A (en) * 1961-10-16 1965-11-16 Oesterr Alpine Montan Process for the production of high alloyed steels
US3467167A (en) * 1966-09-19 1969-09-16 Kaiser Ind Corp Process for continuously casting oxidizable metals
US3751242A (en) * 1969-04-02 1973-08-07 Eisenwerk Gmbh Sulzbach Rosenb Process for making chrimium alloys
US3725041A (en) * 1970-09-25 1973-04-03 Allegheny Ludlum Ind Inc Deoxidizing metal

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4518422A (en) * 1982-11-17 1985-05-21 Arbed S.A. Process and apparatus for refining steel in a metallurgical vessel
US4481032A (en) * 1983-08-12 1984-11-06 Pfizer Inc. Process for adding calcium to a bath of molten ferrous material

Also Published As

Publication number Publication date
IT1015605B (it) 1977-05-20
ATA544874A (de) 1977-05-15
BE817256A (fr) 1974-11-04
SE7408783L (enExample) 1975-01-07
JPS5038617A (enExample) 1975-04-10
DE2333937B1 (de) 1974-12-05
GB1432290A (en) 1976-04-14
DE2333937C2 (de) 1975-07-17
CA1015169A (en) 1977-08-09
LU70449A1 (enExample) 1974-11-28
NL7408838A (nl) 1975-01-07
AT340975B (de) 1978-01-10
DK356774A (enExample) 1975-03-17
FR2236007B3 (enExample) 1977-05-06
FR2236007A1 (enExample) 1975-01-31

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