US3865578A - Composition for treating steels - Google Patents
Composition for treating steels Download PDFInfo
- Publication number
- US3865578A US3865578A US324244A US32424473A US3865578A US 3865578 A US3865578 A US 3865578A US 324244 A US324244 A US 324244A US 32424473 A US32424473 A US 32424473A US 3865578 A US3865578 A US 3865578A
- Authority
- US
- United States
- Prior art keywords
- composition
- molten steel
- fluoride
- steel
- melting point
- 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 - Lifetime
Links
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
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/076—Use of slags or fluxes as treating agents
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Definitions
- the present invention relates to a novel composition for treating molten steel which is effective to clean molten steel, particularly Al-killed molten steel prepared in various steel making furnaces, and is added to the molten steel during tapping and for ingot making steps.
- the present composition has remarkably enhanced cleaning effects and contributes to improve yield of steel ingot production.
- present composition is useful for production of various carbon steels, alloy steels, stainless steels and highly alloyed steels, and remarkably reduces both interior defects and surface defects of steel materials, thus greatly improving yield of steel products.
- One of the objects of the present invention is to provide a novel composition for treating various kinds of steels.
- the basic composition according to the present invention comprises:
- a modified composition according to the present invention comprises:
- fluorides of rare earth elements or misch metal powders may be added in place of cerium fluoride.
- non-metallic inclusions are caused by entrappment of furnace slag during the teeming opertion, secondary oxidation of the molten steel in the air, the ladle reaction between molten steel and refractories and the melt down of refractories during the bottom-pouring ingot making operation.
- These non-metallic inclusions contain A type inclusions such as sulfides and silicates, B type granular inclusions such as alumina inclusions discontinuously grouping in the hot working direction, and C type inclusions such as granular oxides irregularly dispersed and not deformed by the hot working.
- this object can be achieved by introducing oxides which are able to combine with the formed oxides into the molten steel in the ladle or during the ingot-making process to produce low melting point coagulates by the reaction between the oxides and then by adding com positions which generate suitable gassing which intensifies collision action among the inclusions to accelerate the coagulation speed and enlargement of the coagulates, thus increasing the floating up of inclusions according to the flotation principle.
- lithium oxide which has larger coagulation action with respect to the oxides in the molten steel, is very useful; and for the source of the lithium oxide, a low melting point lithium fluoride has been selected.
- the lithium fluoride easily reacts with oxygen in the molten steel and forms lithium oxide which is an oxide having highly activated energy, and reacts with alumina and oxides formed in the molten steel and forms low melting point complexes and coagulates.
- Sodium fluoride is also a low melting point fluoride and generates suitable gassing at the temperature of molten steel and is useful for a gas generating source for increasing the floating up-power of coagulated oxides.
- the reaction which contributes to the removal of the non-metallic inclusions by bondage of oxides may be expressed as LiF O Li O F and some of the coagulated oxides are:
- the non-metallic inclusions given coagulation ability are adsorbed and fixed by the complex molten slag as the floating power is increased by the gas from sodium fluoride as well as by the vapour pressure of lithium fluoride and calcium fluoride.
- the amount of calcium fluoride should be proportionate to the formation of the molten slag layer necessary for adsorbing and fixing the floating oxides, and less than 30 wt.% of calcium fluoride is not enough for the above purpose and more than wt.% of calcium fluoride is excessive in view of the total slag amount effective for improving steel ingot surfaces.
- the proportions of the components are also adjusted in relation with the melting point of the compositions.
- hexafluoro titanic acid potassium is added to the basic composition as hereinbefore stated.
- This additional component is effective to aid desulfurization of the molten steel and has a low melting point of about 780C and yet is lower in price than lithium fluoride, and thus useful for fine adjustment of the melting point of the composition. This effect can be attained with less than 3% thereof.
- cerium fluoride is added for the purpose of supplementary adjustment for cleaness of the molten steel in an amount not more than 3% in view of controlling precipitation of cerium oxide.
- the melting point of cerium fluoride is about 1,3 30C.
- the components of the composition according to the present invention are selected so as to have a melting point within a range of 600 l,lOOC.
- the melting points of simple fluorides are:
- LiF 845C, NaF 990C and CaF l,4l8C and the eutectic temperatures of binary systems are:
- the mixture containing the above fluorides is divided into an appropriate particle size and mechanically mixed uniformly and added to molten steel in the form of powder, granules or briquette.
- the proportions of the components of the composition according to the present invention are changed or adjusted in view of the amount of oxygen remaining in the molten steel which differs depending on the steel grades or types such as low-carbon steel grades, middle-carbon steel grades and high-carbon steel grades.
- the range of melting point of the composition is defined broad enough to cover the cases when lowmelting point CeF or K TiF is added.
- the specific gravity of the composition of the present invention is desirably about 1.03 depending on the mixing proportion, and the viscosity is desirably about 0.15 poise at l,300C.
- the cleaning effects attained by addition of the composition of the present invention include deoxidation of molten steel, removal of non-metallic inclusions and improvement of ingot surfaces as well as desulfurization and removal of hydrogen.
- the composition added to the molten steel forms molten slag having a low melting point and low viscosity, and rises together with the molten steel, covering the top surface of the molten steel in the mold during the teeming, and flows downs along the inside wall of the mold in a curtain-like form so that a smooth surface of steel ingot is obtained.
- LiF, NaF and CaF contained in the composition react with sulfur in the molten steel to form Li S,
- H gas enriched during the steel making, tapping and ingot making steps is also taken up together with the gas, and thus the hydrogen gas content is reduced.
- composition of the present invention is added to molten steel in the following manners and amounts.
- the composition is added to the molten steel in an amount of to 1,000g per one metric ton of molten steel, and in case of top-pouring ingot-making, the composition is added in an amount of 300 to l,000g per one metric ton of molten metal.
- the addition of the composition may be carried out by putting part thereof within the mold or the pourer before the molten steel is poured, in an amount of 150 to 300g per one ton of molten steel, and adding the remaining part as required in the mold after the pouring is started, or the composition may be added to the stream of molten metal successively. In any way, the addition of the composition is completed before about half of the molten steel is poured.
- the amount of the composition to be added before the pouring is determined by taking into consideration the method of ingot making and the size of ingots to be obtained.
- composition of the present invention can be added in a divided manner to tandishes for continuous steel casting and similar desirable results are obtained.
- composition of the present invention is applicable for treating various kinds of steels, and its chemical analysis is changed depending on the kind of steels. Preferred chemical analysis of the present composition are set forth under.
- compositions may further comprise 1.0 wt.% of K TiF and/or CeF
- Table 1 shows the chemical analysis of examples of the present composition
- Table 2 shows results obtained when the present composition is used in comparison with results obtained when the present composition is not used.
- Test samples were prepared from 60 mm diameter steel bars rolled from a 6 ton steel ingot, and the estimation was made on the cleanness (.llS: Spot calculation method, number of viewed fields: 60 X 400) of the steel according to the JlSmicroscopic testing method for non-metallic inclusions.
- a composition for treating molten steel consisting essentially of 3-40 wt. of lithium fluoride, 15-50 wt. of sodium fluoride, 30-70 wt. of calcium fluoride and l-3 wt. of K TiF and having a melting point between 600 and l,lO0C.
- a composition for treating molten steel consisting essentially of 3-40 wt. of lithium fluoride. 15-50 wt. of sodium fluoride, 30-70 wt. of calcium fluoride, l-3 wt. of K TiF and l-3 wt. of CeF and having a melting point between 600 and l,l00C.
- composition according to claim 1 which has a particle size under 40 mesh.
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)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP47009220A JPS5038367B2 (ja) | 1972-01-25 | 1972-01-25 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3865578A true US3865578A (en) | 1975-02-11 |
Family
ID=11714338
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US324244A Expired - Lifetime US3865578A (en) | 1972-01-25 | 1973-01-16 | Composition for treating steels |
Country Status (5)
Country | Link |
---|---|
US (1) | US3865578A (ja) |
JP (1) | JPS5038367B2 (ja) |
AU (1) | AU468334B2 (ja) |
DE (1) | DE2303668C3 (ja) |
GB (1) | GB1394304A (ja) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4475960A (en) * | 1982-03-29 | 1984-10-09 | Alcan International Limited | Flux for brazing aluminum and method of employing the same |
US4670067A (en) * | 1985-04-09 | 1987-06-02 | Kabushiki Kaisha Toyota Chuo Kenkyusho | Brazing flux |
US5525163A (en) * | 1991-11-12 | 1996-06-11 | Rockwell International Corporation | Welding compositions |
US5529639A (en) * | 1993-12-28 | 1996-06-25 | Showa Aluminum Corp. | Flux used in the low-temperature brazing and a method of flux brazing a low-melting aluminum material |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS517448B2 (ja) * | 1972-02-28 | 1976-03-08 |
Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2360717A (en) * | 1942-11-27 | 1944-10-17 | Cerium Corp | Method of eliminating aluminate and silicate inclusions |
US2731373A (en) * | 1954-08-10 | 1956-01-17 | Eutectic Welding Alloys | Electrode flux covering for copper and copper-base alloy core materials |
US2805178A (en) * | 1953-04-20 | 1957-09-03 | Ampco Metal Inc | Welding flux composition |
US2814559A (en) * | 1953-04-23 | 1957-11-26 | James A Clark | Process for the production of nodular cast iron |
US3031346A (en) * | 1960-07-25 | 1962-04-24 | Eutectic Welding Alloys | Flux coated silver brazing element and flux compositions therefor |
US3269828A (en) * | 1963-12-05 | 1966-08-30 | Foote Mineral Co | Composition and method for making deoxidized steel |
US3272667A (en) * | 1964-12-10 | 1966-09-13 | Du Pont | Submerged arc welding process and flux composition utilizing fluorocarbon |
US3446614A (en) * | 1965-03-30 | 1969-05-27 | Leonard Terence Johnson | Production of iron alloys |
US3621188A (en) * | 1968-10-25 | 1971-11-16 | Eutectic Corp | Welding electrode |
-
1972
- 1972-01-25 JP JP47009220A patent/JPS5038367B2/ja not_active Expired
-
1973
- 1973-01-16 US US324244A patent/US3865578A/en not_active Expired - Lifetime
- 1973-01-22 AU AU51322/73A patent/AU468334B2/en not_active Expired
- 1973-01-22 GB GB318473A patent/GB1394304A/en not_active Expired
- 1973-01-25 DE DE2303668A patent/DE2303668C3/de not_active Expired
Patent Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2360717A (en) * | 1942-11-27 | 1944-10-17 | Cerium Corp | Method of eliminating aluminate and silicate inclusions |
US2805178A (en) * | 1953-04-20 | 1957-09-03 | Ampco Metal Inc | Welding flux composition |
US2814559A (en) * | 1953-04-23 | 1957-11-26 | James A Clark | Process for the production of nodular cast iron |
US2731373A (en) * | 1954-08-10 | 1956-01-17 | Eutectic Welding Alloys | Electrode flux covering for copper and copper-base alloy core materials |
US3031346A (en) * | 1960-07-25 | 1962-04-24 | Eutectic Welding Alloys | Flux coated silver brazing element and flux compositions therefor |
US3269828A (en) * | 1963-12-05 | 1966-08-30 | Foote Mineral Co | Composition and method for making deoxidized steel |
US3272667A (en) * | 1964-12-10 | 1966-09-13 | Du Pont | Submerged arc welding process and flux composition utilizing fluorocarbon |
US3446614A (en) * | 1965-03-30 | 1969-05-27 | Leonard Terence Johnson | Production of iron alloys |
US3621188A (en) * | 1968-10-25 | 1971-11-16 | Eutectic Corp | Welding electrode |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4475960A (en) * | 1982-03-29 | 1984-10-09 | Alcan International Limited | Flux for brazing aluminum and method of employing the same |
US4556165A (en) * | 1982-03-29 | 1985-12-03 | Alcan International Limited | Method of brazing aluminum employing fluoaluminate flux |
US4670067A (en) * | 1985-04-09 | 1987-06-02 | Kabushiki Kaisha Toyota Chuo Kenkyusho | Brazing flux |
US5525163A (en) * | 1991-11-12 | 1996-06-11 | Rockwell International Corporation | Welding compositions |
US5529639A (en) * | 1993-12-28 | 1996-06-25 | Showa Aluminum Corp. | Flux used in the low-temperature brazing and a method of flux brazing a low-melting aluminum material |
Also Published As
Publication number | Publication date |
---|---|
AU5132273A (en) | 1974-07-25 |
DE2303668B2 (de) | 1978-05-24 |
JPS4879115A (ja) | 1973-10-24 |
AU468334B2 (en) | 1976-01-08 |
GB1394304A (en) | 1975-05-14 |
DE2303668C3 (de) | 1979-01-25 |
DE2303668A1 (de) | 1973-07-26 |
JPS5038367B2 (ja) | 1975-12-09 |
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