GB2043696A - Adjusting carbon contents of steel melts - Google Patents
Adjusting carbon contents of steel melts Download PDFInfo
- Publication number
- GB2043696A GB2043696A GB8003030A GB8003030A GB2043696A GB 2043696 A GB2043696 A GB 2043696A GB 8003030 A GB8003030 A GB 8003030A GB 8003030 A GB8003030 A GB 8003030A GB 2043696 A GB2043696 A GB 2043696A
- Authority
- GB
- United Kingdom
- Prior art keywords
- steel
- carbon content
- bath
- iron
- iron carbide
- 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.)
- Withdrawn
Links
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 59
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 57
- 239000000161 steel melt Substances 0.000 title 1
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 53
- 239000010959 steel Substances 0.000 claims abstract description 53
- 229910001567 cementite Inorganic materials 0.000 claims abstract description 24
- 238000004519 manufacturing process Methods 0.000 claims abstract description 10
- 238000000034 method Methods 0.000 claims description 18
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 claims description 6
- 229910001882 dioxygen Inorganic materials 0.000 claims description 6
- 239000012159 carrier gas Substances 0.000 claims description 4
- 239000003795 chemical substances by application Substances 0.000 claims description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 abstract description 17
- 229910052742 iron Inorganic materials 0.000 abstract description 10
- 229910000805 Pig iron Inorganic materials 0.000 abstract description 8
- 238000005255 carburizing Methods 0.000 description 6
- 238000007670 refining Methods 0.000 description 6
- 239000003245 coal Substances 0.000 description 5
- 239000000571 coke Substances 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- -1 Iron carbides Chemical class 0.000 description 3
- 238000005275 alloying Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000000155 melt Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000000654 additive Substances 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 238000005303 weighing Methods 0.000 description 2
- 229910017356 Fe2C Inorganic materials 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 239000005864 Sulphur Substances 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 238000005261 decarburization Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- BHEPBYXIRTUNPN-UHFFFAOYSA-N hydridophosphorus(.) (triplet) Chemical compound [PH] BHEPBYXIRTUNPN-UHFFFAOYSA-N 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
Classifications
-
- 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
- C21C7/0025—Adding carbon material
Landscapes
- 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)
- Investigating And Analyzing Materials By Characteristic Methods (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
In the manufacture of steel having an accurately determined carbon content, molten pig iron or raw iron is refined to form a molten steel bath having a lower carbon content than the intended final carbon content of the steel, whereafter the steel bath is carburized by dissolving therein iron carbide in quantities such as to obtain the desired final carbon content.
Description
SPECIFICATION
A method of manufacturing steel
The present invention relates to the manufacture of steel, and more particularlyto a method of manufacturing steel having an accurately determined carbon content.
Carbon is the most important non-metallic alloying element in steel. Small variations in the carbon content of steel cause its properties to vary greatly. Consequently, when producing steel great care is always taken to obtain the exact carbon content required. This is particularly true of highgrade steels, and is also important with respect to commercial steel.
Nowadays, steel is manufactured to a very large extent by oxygen-gas converter processes. In these processes, molten raw iron or pig iron having carbon contents of, e.g., 2 - 4.5 %, is refined, until a steel having the desired carbon content is obtained. Such refinement, however, can also be effected in electrofurnaces or fired furnaces, e.g. Martin-furnaces.
Refining is a particularly rapid process when carried out in oxygen-gas converters, in which the refining process is effected with oxygen-gas or air rich in oxygen. In melts of 200 to 300 tons, the carbon content can be reduced to low values in a very short time, e.g. from 10 - 20 minutes. It is then difficult, however, to stop the refining process at the desired carbon content. Consequently, it is often preferred to continue the refining process until practically all carbon has left the melt, and then to carburize the bath of molten iron to the desired carbon content, by adding products having a high carbon content, e.g.
graphite. Refining down to low carbon contents is also desirable for other reasons. It is only when the iron melt has obtained a low carbon content that the melt is purified, by blowing oxygen gas thereinto, from certain impurities, such as phosphorous, to an extent which makes it suitable as a starting material for the manufacture of steel of high quality.
When carburizing the molten iron, other alloying substances may be added thereto, in order to impart desirable properties to the finished steel. The alloying substances, however, should not contain substances undesirable in the finished steel. They should also be readily soluble in the steel, and should chill the steel to thejleast possible extent.
Thus, it is normal to refine the molten raw iron or pig iron in the aforedescribed manner, to low carbon contents lying considerably beneath the intended final carbon content, before carburizing the bath.
The carbon content, however, can also be adjusted to the correct value with a lesser degree of carburization, by commencing from a value immediately beneath the desired final carbon content.
Difficulties have been found in finding a suitable carburizing material, which combines cheapness with the possibility of obtaining the desired result in a carburizing operation. Thus, if powdered coal or powdered coke is used, the steel becomes contaminated with the impurities, such as sulphur, present in the coal or coke. Further, because coal and coke are light materials, greatly varying yields are obtained when adding coal or coke to the steel, which makes it difficult to obtain a correct analysis. Pure carbon materials, such as graphite, are light in weight, expensive and difficult to dissolve in the steel bath in a manner such as to give reproduceable yields, which result in errors with regard to the composition of the steel. If, for example, pig iron is used, the temperature ofthe steel bath drops markedly.
Further, pig iron contains impurities which often cannot be permitted to enter the steel bath in the final steel-manufacturing stage.
An object of the present invention is to provide a novel and useful method of obtaining in the manufacture of steel an accurately determined carbon content of the final steel.
To this end it is proposed in accordance with the invention that iron-carbide is dissolved in a molten steel bath having a lower carbon content than the desired final carbon content of the steel, in a quantity which provides the desired final carbon content. In this way, the disadvantages associated to a high degree with the use of conventional carburizing agents are eliminated, in that a high yield and a high degree of precision with regard to the composition of the steel can be obtained with a cheap material.
Iron carbides, which contain only iron and carbon, can be produced with a high degree of purity at a relatively low price. Iron carbides, which may have varying compositions, e.g. Fe2C, Fe3C etc., have a high carbon content compared with pig iron, and are readily soluble in steel baths having low carbon contents. The dissolution of the iron carbide in the bath will only cause the bath to be relatively slightly cooled i.e. only results in a small loss in temperature.
Moreover, iron carbides are heavy, which enables them to be charged to the steel bath in a substantially loss-free manner. The method according to the invention can be applied to particular advantage when manufacturing steel in oxygen-gas steel converters, in which the rapid refining sequence renders it difficult to stop the decarburization at a point of time so exact that the correct carbon content is obtained.
The iron carbide is suitably injected into the bath in particle form, suspended in a carrier gas.
It is also possible, however, to charge the iron carbide to the bath in agglomerated form, thereby rendering it unnecessary to suspend the iron carbide in a substantially inert carrier gas.
In this respect, it is possible to utilize the high specific weight of the iron carbide by charging said carbide to the steel bath in the form of agglomerates which also contain deoxidizing agents, such as aluminium, and/or free carbon, in order to increase the yield of the last mentioned additives.
The iron carbide can suitably be charged either to a stream of running steel or to the bottom of a container or ladle in which the steel having a lower carbon content than the intended final carbon content is poured.
The iron carbide can be charged to an unalloyed steel bath orto a bath which has already been alloyed. Alternatively, the iron carbide can be charged to the bath simultaneously with other substances or additives.
The invention will now be exemplified through a number of examples.
Example I
A bath of molten steel weighing 5800 kg and contained in a 6 ton electrosteel furnace had a carbon content of 0.04 % by weight, which was to be raised to a final carbon content of 0.20 % by weight.
To this end, 147.7 kg of finely-divided iron-carbide having a carbon content of 6.5 % by weight was injected into the bath with the aid of an inert carrier gas. As can be calculated, the bath, including the carbide added thereto, required an addition of 9.56 kg carbon in order to raise its carbon content to 0.20 %, and that the carbide charge contained 9.6 kg carbon. Thus, the carbon yield was 99.6 %. The initial temperature of the bath was 1720 C and fell to 16100C during the carburization process.
Example II The carbon content of a molten steel bath weighting 5980 kg was raised from 0.19 by weight to 0.28 by weight by charging to the bath, as it was poured into a ladle, 98.95 kg of iron-carbide having a carbon content of 5.7 % by weight. The amount of carbon added through the iron carbide was 5.64 kg, while the amount of carbon dissolved in the bath was 5.63 kg, thus showing a yield of 99.8 %. The initial temperature of the bath was 1700 C and fell to 1615"C during the carburization process.
Example Ill The carbon content of a molten steel bath weighing 5050 kg was raised from 0.03 % by weight to 0.14 % by weight, by charging to the bath, as it was poured into a ladle,100 of or iron-carbide having a carbon content of 5.67 % by weight. The amount of carbon added through the iron-carbide was 5.67 kg, while the amount of carbon dissolved in the bath was also 5.67 kg, thus showing a yield of 100 %. The initial temperature of the bath was 17100C and fell to 1630"C during the carburization process.
The above Examples show that iron-carbide is an extremely suitable carbu rizing agent for accurately adjusting the carbon content of molten steel. Carburization using powder coal does not, by far, provide the above yields while, e.g., the use of pig iron for carburization purposes causes the bath to be excessively chilled, e.g. a tempe,ature drop in the order of 150"C; in addition hereto the impurities contained in pig iron will be alloyed with the steel.
Claims (9)
1. A method of manufacturing steel having an accurately determined carbon content, comprising dissolving iron carbide in a molten steel bath whose carbon content is lower than the desired carbon content of the steel, said carbide being added in quantities such as to obtain the intended final carbon content.
2. A method according to claim 1, comprising adding the iron carbide to steel manufactured in oxygen-gas steel converters.
3. A method according to claim 1 or claim 2, comprising injecting intothesteel bath particulate iron carbide suspended in a carrier gas.
4. A method according to claim 1 or claim 2, comprising charging the iron carbide in agglomerated form to the steel bath.
5. A method according to claim 4, comprising charging the iron carbide to the bath in the form of agglomerates which also contain deoxidizing agents andlorfree carbon.
6. A method according to any one of claims 1 - 5, comprising charging the iron carbide to a stream of running steel.
7. A method according to any one of claims 1 - 5, comprising charging the iron carbide to the bottom of a container or ladle in which the steel having a carbon content lower than the intended final carbon content is poured.
8. A method of manufacturing steel substantially as hereinbefore described with reference to Example l, II or lil.
9. Steel having an accurately determined carbon content when produced by a method according to any of the preceding Claims.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE7901372A SE7901372L (en) | 1979-02-15 | 1979-02-15 | SET FOR MANUFACTURE OF STEEL |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2043696A true GB2043696A (en) | 1980-10-08 |
Family
ID=20337312
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8003030A Withdrawn GB2043696A (en) | 1979-02-15 | 1980-01-29 | Adjusting carbon contents of steel melts |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS55113823A (en) |
| BE (1) | BE881720A (en) |
| DE (1) | DE3003915A1 (en) |
| FR (1) | FR2449126A1 (en) |
| GB (1) | GB2043696A (en) |
| IT (1) | IT1129686B (en) |
| LU (1) | LU82160A1 (en) |
| NL (1) | NL8000724A (en) |
| SE (1) | SE7901372L (en) |
Cited By (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1998027232A1 (en) * | 1996-12-18 | 1998-06-25 | Technological Resources Pty. Ltd. | Producing iron from solid iron carbide |
| US6143054A (en) | 1997-09-26 | 2000-11-07 | Technological Resources Pty Ltd. | Process of producing molten metals |
| US6270553B1 (en) | 1996-12-18 | 2001-08-07 | Technological Resources Pty. Ltd. | Direct reduction of metal oxide agglomerates |
| US6379424B1 (en) | 1999-10-26 | 2002-04-30 | Technological Resources Pty. Ltd. | Direct smelting apparatus and process |
| US6379422B1 (en) | 1999-08-05 | 2002-04-30 | Technological Resources Pty. Ltd. | Direct smelting process |
| US6387153B1 (en) | 1999-10-15 | 2002-05-14 | Technological Resources Pty Ltd | Stable idle procedure |
| US6402808B1 (en) | 1998-07-24 | 2002-06-11 | Technological Resources Pty. Ltd. | Direct smelting process |
| US6423114B1 (en) | 1999-08-10 | 2002-07-23 | Technological Resources Pty. Ltd. | Pressure control |
| US6423115B1 (en) | 1999-01-08 | 2002-07-23 | Technological Resources Pty Ltd | Direct smelting process |
| US6428603B1 (en) | 1999-09-27 | 2002-08-06 | Technological Resources Pty., Ltd. | Direct smelting process |
| US6440195B1 (en) | 1998-10-14 | 2002-08-27 | Technological Resources Pty. Ltd. | Process and an apparatus for producing metals and metal alloys |
| US6475264B1 (en) | 1998-07-24 | 2002-11-05 | Technological Resources Pty Ltd | Direct smelting process |
| US6478848B1 (en) | 1998-09-04 | 2002-11-12 | Technological Resources Pty Ltd | Direct smelting process |
| US6517605B1 (en) | 1999-07-09 | 2003-02-11 | Technological Resources Pty. Ltd. | Start-up procedure for direct smelting process |
| US6585929B1 (en) | 1999-06-08 | 2003-07-01 | Technological Resources Pty Ltd | Direct smelting vessel |
| US6602321B2 (en) | 2000-09-26 | 2003-08-05 | Technological Resources Pty. Ltd. | Direct smelting process |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR320682A (en) * | 1902-04-25 | 1902-12-17 | Electro Metallurg Francaise | A process for deoxidizing and carburizing liquid steel |
| FR1451587A (en) * | 1964-08-04 | 1966-01-07 | Forges De Thy Marcinelle | Process and plant for recarburizing steel |
| JPS5223039B2 (en) * | 1973-05-31 | 1977-06-21 |
-
1979
- 1979-02-15 SE SE7901372A patent/SE7901372L/en not_active Application Discontinuation
-
1980
- 1980-01-29 GB GB8003030A patent/GB2043696A/en not_active Withdrawn
- 1980-01-31 IT IT19582/80A patent/IT1129686B/en active
- 1980-02-04 DE DE19803003915 patent/DE3003915A1/en not_active Withdrawn
- 1980-02-05 NL NL8000724A patent/NL8000724A/en not_active Application Discontinuation
- 1980-02-07 FR FR8002659A patent/FR2449126A1/en not_active Withdrawn
- 1980-02-12 LU LU82160A patent/LU82160A1/en unknown
- 1980-02-14 BE BE0/199397A patent/BE881720A/en unknown
- 1980-02-15 JP JP1676680A patent/JPS55113823A/en active Pending
Cited By (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6270553B1 (en) | 1996-12-18 | 2001-08-07 | Technological Resources Pty. Ltd. | Direct reduction of metal oxide agglomerates |
| CN1071795C (en) * | 1996-12-18 | 2001-09-26 | 技术资源有限公司 | Producing iron from solid iron carbide |
| WO1998027232A1 (en) * | 1996-12-18 | 1998-06-25 | Technological Resources Pty. Ltd. | Producing iron from solid iron carbide |
| US6143054A (en) | 1997-09-26 | 2000-11-07 | Technological Resources Pty Ltd. | Process of producing molten metals |
| US6475264B1 (en) | 1998-07-24 | 2002-11-05 | Technological Resources Pty Ltd | Direct smelting process |
| US6402808B1 (en) | 1998-07-24 | 2002-06-11 | Technological Resources Pty. Ltd. | Direct smelting process |
| US6478848B1 (en) | 1998-09-04 | 2002-11-12 | Technological Resources Pty Ltd | Direct smelting process |
| US6440195B1 (en) | 1998-10-14 | 2002-08-27 | Technological Resources Pty. Ltd. | Process and an apparatus for producing metals and metal alloys |
| US6423115B1 (en) | 1999-01-08 | 2002-07-23 | Technological Resources Pty Ltd | Direct smelting process |
| US6585929B1 (en) | 1999-06-08 | 2003-07-01 | Technological Resources Pty Ltd | Direct smelting vessel |
| US6517605B1 (en) | 1999-07-09 | 2003-02-11 | Technological Resources Pty. Ltd. | Start-up procedure for direct smelting process |
| US6379422B1 (en) | 1999-08-05 | 2002-04-30 | Technological Resources Pty. Ltd. | Direct smelting process |
| US6423114B1 (en) | 1999-08-10 | 2002-07-23 | Technological Resources Pty. Ltd. | Pressure control |
| US6428603B1 (en) | 1999-09-27 | 2002-08-06 | Technological Resources Pty., Ltd. | Direct smelting process |
| US6387153B1 (en) | 1999-10-15 | 2002-05-14 | Technological Resources Pty Ltd | Stable idle procedure |
| US6379424B1 (en) | 1999-10-26 | 2002-04-30 | Technological Resources Pty. Ltd. | Direct smelting apparatus and process |
| US6602321B2 (en) | 2000-09-26 | 2003-08-05 | Technological Resources Pty. Ltd. | Direct smelting process |
Also Published As
| Publication number | Publication date |
|---|---|
| SE7901372L (en) | 1980-08-16 |
| DE3003915A1 (en) | 1980-08-21 |
| NL8000724A (en) | 1980-08-19 |
| IT8019582A0 (en) | 1980-01-31 |
| BE881720A (en) | 1980-08-14 |
| FR2449126A1 (en) | 1980-09-12 |
| JPS55113823A (en) | 1980-09-02 |
| IT1129686B (en) | 1986-06-11 |
| LU82160A1 (en) | 1980-05-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |