US3417463A - Method of producing steel for sheets to be enamelled by the single-coat method - Google Patents

Method of producing steel for sheets to be enamelled by the single-coat method Download PDF

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Publication number
US3417463A
US3417463A US562506A US56250666A US3417463A US 3417463 A US3417463 A US 3417463A US 562506 A US562506 A US 562506A US 56250666 A US56250666 A US 56250666A US 3417463 A US3417463 A US 3417463A
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steel
sheets
enamelled
carbon content
content
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US562506A
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Knuppel Helmut
Brotzmann Karl
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Eisenwerke Gesellschaf Maximilianshuette mbH
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Eisenwerke Gesellschaf Maximilianshuette mbH
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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
    • C21C7/10Handling in a vacuum
    • YGENERAL 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
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00Metal working
    • Y10T29/49Method of mechanical manufacture
    • Y10T29/4998Combined manufacture including applying or shaping of fluent material
    • Y10T29/49988Metal casting
    • Y10T29/49991Combined with rolling

Definitions

  • the present invention comprises a method by which the particular composition, particularly the carbon content of the steel, can be adjusted by metallurgical measures and sheets produced without any special annealing treatment.
  • the method of this invention makes use of conventional refining processes, preferably the oxygen blowing process, by which a steel is produced having a carbon content of about 0.03 to 0.06% and a comparatively high oxygen content of about 0.10 to 0.12%.
  • Deoxidation elements preferably aluminium
  • the addition of aluminium should be so calculated that the free aluminium content of the melt amounts to less than 0.015%.
  • the desired low aluminium content may be reliably obtained by introducing a quantity of aluminium of about 1 kg. into the vacuum plant per ton of steel.
  • the melt is advantageously vigorously mixed for a short period, so that, with a slight excess of aluminium, the soluble aluminium fraction is substantially reduced by reaction with the iron oxide absorbed from the refractory lining.
  • Steel produced in this manner is cast into slabs or ingots when it can be rolled in the usual way. It can be cast particularly satisfactorily in a continuous casting machine, since the dilficulties which otherwise occur in the casting of steels having a low aluminium content by the continuous casting method, resulting from peripheral blow holes, are in this case entirely eliminated.
  • boron As a further feature of the method of this invention about 0.005% of boron is added to the steel after the removal of carbon and oxygen. It has been found that by adding boron it is possible to compensate for small unintentional fluctuations in the oxygen content, thereby reliably obtaining an optimum solidification structure without peripheral blow holes. In addition, the addition of boron improves the ability of the sheets to be pickled, so that only small quantities of iron have to be removed in order to obtain good adhesion of the enamel coating.
  • Example A steel refined in an oxygen blowing converter to a carbon content of 0.04% and an oxygen content of 0.10% is subjected after tapping to vacuum treatment.
  • the latter will be explained with the aid of a vacuum syphon process, which is the subject of British Patent No. 801,518.
  • the steel contained in a pouring ladle is drawn by suction, a part at a time into a degasification vessel situated above the pouring ladle and after degasification is returned to the latter, simultaneously being mixed with the steel contained in the ladle.
  • the result of this treatment is a steel having the following composition:
  • the steel is cast into slabs by top-pouring, a high pouring speed producing the best surface results.
  • the steel was then enameled by the single-coat method, excellent adhesion of the enamel coating being obtained by removal of only about 15 grams per square metre of surface instead-of the removal of 40 grams per square metre of surface which is otherwise customary in the pickling process.
  • a method of producing steel for sheets to be enamelled by the single-coat method which comprises the steps of (a) producing by a refining process a steel having a composition which has a relatively high oxygen content of about 0.10 to 1.12% with a carbon content of 0.03 to 0.06% thereafter (b) treating the steel melt to reduce its carbon content to below about 0.01%, (0) subjecting the steel to a deoxidation treatment in vacuo to reduce the oxygen content to a predetermined level, (d) vigorously mixing the steel in vacuo, (e) pouring the steel to produce slabs, and (f) rolling the slabs into sheets.
  • a method of producing steel for sheets to be enamelled by the single-coat method which comprises the steps of (a) producing by a refining process a steel having a composition which has a relatively high oxygen content of about 0.10% with a carbon content of 0.04% thereafter (1)) treating the steel melt to reduce its carbon content to below about 0.01%, (c) subjecting the steel to a deoxidation treatment in vacuo to reduce the oxygen content to a predetermined level, ((1) vigorously mixing the steel in vacuo, (e) pouring the steel to produce slabs, and (f) rolling the slabs into sheets.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
  • Treatment Of Steel In Its Molten State (AREA)

Description

United States Patent 3,417,463 METHOD OF PRODUCING STEEL FOR SHEETS TO BE ENAMELLED BY THE SINGLE-COAT METHOD Helmut Kniippel, Sulzbach-Rosenberg Hutte, and Karl Brotzmann, Amberg, Germany, assignors to Eisenwerke- Gesellschaft Maximiliansliutte m.b.H., Sulzbach-Rosenberg Hutte, Germany, a corporation of Germany No Drawing. Filed July 5, 1966, Ser. No. 562,506 Claims priority, application Germany, July 9, 1965, E 29,679 9 Claims. (Cl. 29-528) In recent years single-coat enamelling methods have been increasingly used in industry because of their simplicity and the quality of the enamel coating, but principally because of the substantially reduced sensitivity to deformation and impact stresses. However, they impose special requirements on the material to be enamelled, particularly in respect of its carbon content, which must be very low. Since hitherto it has not been possible by conventional metallurgical methods to produce steels having sufiiciently low carbon contents, the expedient has been adopted of reducing the carbon content of steel sheet by existing but expensive annealing processes. In addition to high cost, however, such methods of annealing have the disadvantage that undesirable variations occur in the technological properties of the material, which are caused mainly by the formation of coarse grains and partial scaling of the grain boundaries.
The present invention comprises a method by which the particular composition, particularly the carbon content of the steel, can be adjusted by metallurgical measures and sheets produced without any special annealing treatment.
The method of this invention makes use of conventional refining processes, preferably the oxygen blowing process, by which a steel is produced having a carbon content of about 0.03 to 0.06% and a comparatively high oxygen content of about 0.10 to 0.12%. By vacuum treatment the carbon content of the steel is thereupon reduced to below about 0.01%, whereupon the melt is brought to an oxygen content of about 0.08% by the known reaction C+O=CO. Deoxidation elements, preferably aluminium, are then added to the steel in vacuo. The addition of aluminium should be so calculated that the free aluminium content of the melt amounts to less than 0.015%. The desired low aluminium content may be reliably obtained by introducing a quantity of aluminium of about 1 kg. into the vacuum plant per ton of steel. After addition of the aluminium, the melt is advantageously vigorously mixed for a short period, so that, with a slight excess of aluminium, the soluble aluminium fraction is substantially reduced by reaction with the iron oxide absorbed from the refractory lining.
Steel produced in this manner is cast into slabs or ingots when it can be rolled in the usual way. It can be cast particularly satisfactorily in a continuous casting machine, since the dilficulties which otherwise occur in the casting of steels having a low aluminium content by the continuous casting method, resulting from peripheral blow holes, are in this case entirely eliminated.
For certain existing single-coat enamelling processes it is necessary to use sheets having an extremely low carbon content, that is to say those having a carbon content of less than 0.005%. In order to achieve such values it is advisable to assist the vacuum treatment by introducing an inert flushing gas. However, here again it is essential for removal of the carbon to be effected with a relatively high oxygen content of the steel (C+O=CO) and that the free oxygen content should ice be reduced only after the removal of carbon, by adding deoxidising agents, preferably aluminium.
As a further feature of the method of this invention about 0.005% of boron is added to the steel after the removal of carbon and oxygen. It has been found that by adding boron it is possible to compensate for small unintentional fluctuations in the oxygen content, thereby reliably obtaining an optimum solidification structure without peripheral blow holes. In addition, the addition of boron improves the ability of the sheets to be pickled, so that only small quantities of iron have to be removed in order to obtain good adhesion of the enamel coating.
Example A steel refined in an oxygen blowing converter to a carbon content of 0.04% and an oxygen content of 0.10% is subjected after tapping to vacuum treatment. The latter will be explained with the aid of a vacuum syphon process, which is the subject of British Patent No. 801,518. In this process the steel contained in a pouring ladle is drawn by suction, a part at a time into a degasification vessel situated above the pouring ladle and after degasification is returned to the latter, simultaneously being mixed with the steel contained in the ladle. In the present case a fraction of about 10 tons is drawn by suction into the degasification vessel from the total quantity of 60 tons of steel contained in the pouring ladle, and after degasification is returned to the ladle through variation in the difference in height between the latter and the degasification vessel. This partial treat ment lasts about 15 seconds. After about 1.5 minutes therefore the entire content of the ladle has passed once through the degasification vessel. This treatment is continued for about 10 minutes, at the end of which the steel contained in the ladle will have passed about 8 times through the degasification vessel. During this time nitrogen is additionally introduced as a flushing gas through the suction inlet of the degasification. vessel and after the adjustment of the carbon content to the required amount, aluminium is added in vacuo at the rate of 1 kg. per ton, followed after about two minutes by addition of boron in the form of 20% ferroboron at the rate of 50 g. per ton. Two further mixing operations complete the vacuum treatment.
The result of this treatment is a steel having the following composition:
C, 0.005%; 0 0.006%; soluble Al, 0.008%; B 0.004%.
The steel is cast into slabs by top-pouring, a high pouring speed producing the best surface results. After rolling in the usual manner into cold-rolled sheets of a thickness of 1 mm., the steel was then enameled by the single-coat method, excellent adhesion of the enamel coating being obtained by removal of only about 15 grams per square metre of surface instead-of the removal of 40 grams per square metre of surface which is otherwise customary in the pickling process.
What is claimed is:
1. A method of producing steel for sheets to be enamelled by the single-coat method, which comprises the steps of (a) producing by a refining process a steel having a composition which has a relatively high oxygen content of about 0.10 to 1.12% with a carbon content of 0.03 to 0.06% thereafter (b) treating the steel melt to reduce its carbon content to below about 0.01%, (0) subjecting the steel to a deoxidation treatment in vacuo to reduce the oxygen content to a predetermined level, (d) vigorously mixing the steel in vacuo, (e) pouring the steel to produce slabs, and (f) rolling the slabs into sheets.
2. The method claimed in claiml', in which the refining treatment is carried out by oxygen blowing.
3. The method claimed in claim 1 in which deoxidation of the steel is effected by the addition of aluminium to the melt.
4. The method claimed in claim 1 in which the refining process is carried out to a stage in which the steel has a carbon content of about 0.04% and an oxygen content of about 0.10%.
5. A method of producing steel for sheets to be enamelled by the single-coat method, which comprises the steps of (a) producing by a refining process a steel having a composition which has a relatively high oxygen content of about 0.10% with a carbon content of 0.04% thereafter (1)) treating the steel melt to reduce its carbon content to below about 0.01%, (c) subjecting the steel to a deoxidation treatment in vacuo to reduce the oxygen content to a predetermined level, ((1) vigorously mixing the steel in vacuo, (e) pouring the steel to produce slabs, and (f) rolling the slabs into sheets.
6. The method claimed in claim 5 in which following the refining process the steel is subjected to vacuum treatment by the syphon method in which a portion of the steel contained in a casting ladle is withdrawn by suction into a degasification vessel disposed above the casting ladle and after degasification returned to the ladle, the operation being continued until the carbon content has been reduced as required.
7. The method claimed in claim 6 in which about 1 kg. of aluminium per ton is added in vacuo to the steel after adjustment of the carbon content, and after repeated mixing the steel in the vacuum container by varying the distance between the latter and the pouring ladle, the charge is tapped into conventional steel works or continuous casting moulds.
8. The method claimed in claim 7 in which during degasification treatment of the steel, nitrogen is introduced into the vacuum container through the suction inlet.
9. The method claimed in claim 3 in which after deoxidation with aluminium the steel is alloyed in vacuo with boron, advantageously by adding grams of boron per ton in the form of 20% ferroboron.
References Cited UNITED STATES PATENTS 2,848,317 8/1958 Coupette et a1. 164-55 X 2,983,598 5/ 1961 Wheatley.
2,893,860 7/1959 Lorenz 164--61 X 3,071,458 1/1963 Finkl 164-56 X 3,084,038 4/ 1963 Finkl 164--56 X 3,182,359 5/1965 Gero 16455 X 3,215,567 11/ 1965 Yoshida.
3,240,588 3/1966 Finkl 164-61 X 3,306,731 2/1967 Messing 164-65 X CHARLIE T. MOON, Primary Examiner.
PAUL M. COHEN, Assistant Examiner.
US. Cl. X.R. 164-266, 61,

Claims (1)

1. A METHOD OF PRODUCING STEEL FOR SHEETS TO BE ENAMELLED BY THE SINGLE-COAT METHOD, WHICH COMPRISES THE STEPS OF (A) PRODUCING BY A REFINING PROCESS A STEEL HAVING A COMPOSITION WHICH HAS A RELATIVELY HIGH OXYGEN CONTENT OF ABOUT 0.10 TO 1.12% WITH A CARBON CONTENT OF 0.03 TO 0.06% THEREAFTER (B) TREATING THE STEEL MELT TO REDUCE ITS CARBON CONTENT TO BELOW ABOUT 0.01%, (C) SUBJECTING THE STEEL TO A DEOXIDATION TREATMENT IN VACUO TO REDUCE THE OXYGEN CONTENT TO A PREDETERMINED LEVEL, (D) VIGOROUSLY MIXING THE STEEL IN VACUO, (E) POURING THE STEEL TO PRODUCE SLABS, AND (F) ROLLING THE SLABS INTO SHEETS.
US562506A 1965-07-09 1966-07-05 Method of producing steel for sheets to be enamelled by the single-coat method Expired - Lifetime US3417463A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3607229A (en) * 1967-02-14 1971-09-21 Maximilianshuette Eisenwerk Process for the production of low carbon steel
US3792999A (en) * 1971-02-05 1974-02-19 Hoerder Huettenunion Ag Method of producing a drawing and deep drawing steel resistant to ageing, particularly for single-coat enamelling
US3950191A (en) * 1974-10-21 1976-04-13 Kawasaki Steel Corporation Cold rolled steel sheets having an excellent enamelability and a method for producing said cold rolled steel sheets
EP0663449A1 (en) * 1993-12-30 1995-07-19 LTV Steel Company, Inc. Method of making high nitrogen content steel

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2723964B1 (en) * 1994-08-29 1997-03-14 Lorraine Laminage PROCESS FOR PREPARING STEEL FOR PACKAGING SUITABLE FOR DEEP STAMPING AND STEEL OBTAINED BY THIS PROCESS
FR2738259B1 (en) * 1995-09-06 1997-10-03 Lorraine Laminage METHOD FOR MANUFACTURING A STEEL STRIP FOR PACKAGING

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2848317A (en) * 1955-01-13 1958-08-19 Bochumer Ver Fur Gussstahlfabr Desulfurizing of steel
US2893860A (en) * 1957-02-21 1959-07-07 Heraeus Gmbh W C Method and apparatus for continuously degassing molten metals, particularly steel, by evacuation
US2983598A (en) * 1958-12-15 1961-05-09 Smith Corp A O Method of making corrosion-resistant steel
US3071458A (en) * 1960-05-09 1963-01-01 Finkl & Sons Co Method of adding charge material to molten metal under vacuum
US3084038A (en) * 1959-11-25 1963-04-02 Finkl & Sons Co Method and apparatus for combined stream and ladle degassing
US3182359A (en) * 1961-12-27 1965-05-11 Gero Metallurg Corp Vacuum casting apparatus
US3215567A (en) * 1961-09-16 1965-11-02 Kawasaki Steel Co Deep drawing non-aging cold rolled steel sheet and a method of producing the same
US3240588A (en) * 1961-01-09 1966-03-15 Finkl & Sons Co Method and apparatus for treating molten metal
US3306731A (en) * 1963-11-20 1967-02-28 Standard Messo Ges Fur Chemiet Method of degassing steel

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2848317A (en) * 1955-01-13 1958-08-19 Bochumer Ver Fur Gussstahlfabr Desulfurizing of steel
US2893860A (en) * 1957-02-21 1959-07-07 Heraeus Gmbh W C Method and apparatus for continuously degassing molten metals, particularly steel, by evacuation
US2983598A (en) * 1958-12-15 1961-05-09 Smith Corp A O Method of making corrosion-resistant steel
US3084038A (en) * 1959-11-25 1963-04-02 Finkl & Sons Co Method and apparatus for combined stream and ladle degassing
US3071458A (en) * 1960-05-09 1963-01-01 Finkl & Sons Co Method of adding charge material to molten metal under vacuum
US3240588A (en) * 1961-01-09 1966-03-15 Finkl & Sons Co Method and apparatus for treating molten metal
US3215567A (en) * 1961-09-16 1965-11-02 Kawasaki Steel Co Deep drawing non-aging cold rolled steel sheet and a method of producing the same
US3182359A (en) * 1961-12-27 1965-05-11 Gero Metallurg Corp Vacuum casting apparatus
US3306731A (en) * 1963-11-20 1967-02-28 Standard Messo Ges Fur Chemiet Method of degassing steel

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3607229A (en) * 1967-02-14 1971-09-21 Maximilianshuette Eisenwerk Process for the production of low carbon steel
US3792999A (en) * 1971-02-05 1974-02-19 Hoerder Huettenunion Ag Method of producing a drawing and deep drawing steel resistant to ageing, particularly for single-coat enamelling
US3950191A (en) * 1974-10-21 1976-04-13 Kawasaki Steel Corporation Cold rolled steel sheets having an excellent enamelability and a method for producing said cold rolled steel sheets
EP0663449A1 (en) * 1993-12-30 1995-07-19 LTV Steel Company, Inc. Method of making high nitrogen content steel

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