US3912549A - Method for manufacturing a steel for enameling - Google Patents

Method for manufacturing a steel for enameling Download PDF

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Publication number
US3912549A
US3912549A US374390A US37439073A US3912549A US 3912549 A US3912549 A US 3912549A US 374390 A US374390 A US 374390A US 37439073 A US37439073 A US 37439073A US 3912549 A US3912549 A US 3912549A
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Prior art keywords
steel
annealing
enameling
steel sheet
cold
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Expired - Lifetime
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US374390A
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English (en)
Inventor
Hisashi Gondo
Hiroshi Takechi
Mitsunobu Abe
Kazuo Namba
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Nippon Steel Corp
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Nippon Steel Corp
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
    • C21D8/0426—Hot rolling

Definitions

  • the material is a low-carbon steel having not more than 0.25% by weight of Mn, with the particular relation of Mn, S and 0 content. It is hot rolled and coiled at 600C to 800C. It is then cold rolled and annealed for recrystalization. A product having excellent press formability and availability for enameling is thus obtained.
  • the availability for enameling can be judged as fish scaling, bubbling, sagging, boiling, which may be caused after enameling.
  • the fish scaling is caused by the hydrogen entrained in the steel sheet during enameling which is diffused over the surface of the sheet as the time elapses, then breaks the film of the enamel and escapes in the air. In this connection, it has been reported that if there are more voids present inside the steel sheet, the fish scaling less occurs since there are more rooms for the hydrogen to remain.
  • the most common method to form such voids is to deteriorate the purity of the sheet itself. In other words, it is to increase the non-metallic inclusions therein ,so as to utilize the voids occuring in the cold rolling of the steel sheet due to the difference in deformability between the inclusions and the others.
  • the bubbling and the sagging are both the phenomena resulting from the amount of carbon in the steel sheet.
  • the CO or CO gases are generated therefrom, while in the latter case, it is considered to be caused by the fact that due to the lowering of the transformation temperature, the transformation may easily be generated, which results in expansion or contraction of the volume of the material. Accordingly, it is more preferable to have smaller amount of carbon in the material, although it has been reported that it does not raise much problem in a two-coat enameling process.
  • This invention relates to a method for manufacturing a steel for enameling.
  • a method for the manufacture of a cold-rolled lowcarbon steel sheet used for porcelain enamel having excellent press formability and availability for enameling comprising; providing a low carbon steel material having not more than 0.25% by weight of manganese; said steel material containing Mn, 0, and S in the relation of where AW atomic weight; subjecting said steel material to hot rolling followed by coiling the same at 600C to 800C; subjecting said coiled hot rolled strip to cold rolling to thereby obtain a cold rolled strip; and thereafter subjecting said cold rolled strip to recrystalization annealing such as box annealing with over-aging treatment.
  • the starting material used in this invention is a lowcarbon steel having low Mn content.
  • the thin steel sheet to be subjected to press working usually contains more than about 0.30% Mn.
  • an excess amount of Mn exerts an effect upon the mechanical properties of the steel sheet, and in case of the rimmed steel sheet having low-carbon content, it is a common practice to maintain the Mn content as low as possible so as to obtain good surface qualities.
  • the inventors have now found that an appropriate amount of MnS and MnO which is assured by a low Mn content is useful for a continuous annealing treatment.
  • the amount of Mn required in this invention is that necessary to fully fix the harmful S and O which exists as impurities due to the high-temperature coiling of the hot rolled sheet described later.
  • the amount by weight of Mn in the steel may be the chemical equivalent to combine with S and O, or slightly more than that, and it should be not more than 0.25% and preferably 0.20% or less.
  • K of the following equation lies in the range of 0.20 5 K S 0.2, and preferably 0.15 5 K S 0.15 particularly when the prominent effect of this invention is required. It has further been found that the optimum range of K should be 0. 15 to 0 when the excellent enameling characteristic is particularly required.
  • Mn exists in an amount of 0.3% or more as in the conventional steel sheet, it forms an excessive MnS and MnO even if the equation 0.20 i K 5 0.20 is satisfied with respect to S% and 0%, and exerts an adverse effect upon the properties of the steel sheet.
  • This invention has a feature that the relation of Mn, S and O is within the particular range as mentioned above, but it also has a feature that after hot rolling, the hot rolled steel sheet is coiled at high temperature for the purpose of converting the harmful S and 0 into the innocent inclusion in the steel having the particular component range as defined above.
  • the existence ofS and O in the steel gives rise to red shortness as well as restriction of growth of crystal when the annealing for recrystalization is conducted.
  • this invention is intended to convert the harmful S and O to the harmless MnS and MnO by means of coiling the hot rolled steel sheet at high temperature, which will make it possible to suppress the occurrence of the nuclei at the recrystalization annealing so that the circumstances which are favorable for growth of crystal may be obtained; to accelerate the growth of the crystal grains by means of the self-annealing action of the hot rolled coil during the cooling course; and thereby to lessen the strain energy after cold rolling and preferentially enlarge the crystal having orientation capable of increasing the Tvalue at the recrystalization annealing. This is not described in this specification but can be confirmed by measurement by X-ray of the texture.
  • the coiling temperature as mentioned above should be at least 600C, and preferably at least 650C.
  • the difference in temperatures of the hot rolled sheet itself is so severe that the control thereof may become difficult.
  • it should be 800 C or less and the preferable range is between 650C and 800C.
  • the MnS, MnO carbides thus formed may offer an optimum room for making voids at the time of cold rolling, whereby the fish scaling of the steel sheet is considered to be prevented.
  • the occurrence ratio of the fish scaling depends strongly upon the K and the coiling temperature. If the coiling temperature is at least 670C and the K is within the range between 0.2 and 0.2, the occurrence ratio of the fish scaling can be made zero.
  • the K within this range accords with the range in which theTvalue is at least 1.4, which shows that it is the preferable range both for press formability and for availability to enameling.
  • the occurrence ratio of the fish scaling in the drawing is obtained by enameling 50 specimens each having a size of 10cm X 10cm, subjecting the same again to the heat treatment at 400C for 30 minutes and comparing the number of the specimens in which the fish scaling has occurred with others. Even in case of the steel having K of the range in which the occurrence ratio of fish scaling is zero in drawing, the fish scaling properties become much better or occur less often as the K becomes smaller when another more rigid test for juding the fish scaling properties is conducted.
  • the hydrogen pass time the time for the hydrogen gas to reach the reverse side of the sheet
  • the fish scaling properties become remarkably better particularly in the range of K being minus may be that the amount of MnS and MnO is in creased within the range that they do not harm the properties of the material, which result in prominent generation of voids due to the cold rolling.
  • the resulting steel sheet is subjected to the continuous annealing treatment for 700C X 1.5 minutes and then to the overaging treatment for 350C X 5 minutes.
  • the advantage of the present invention can also be confirmed by using the box annealing (700C X 4 hours) after cold rolling and similar preferable results can be obtained.
  • the steel material to which the present invention may be applied is generally one which is produced by converter or other steel manufacturing furnaces, and subjected to the steps of casting, blooming, hot-rolling, etc. and further, cold rolling, continuous annealing including over-aging or box annealing and, if desired, the temper rolling treatment.
  • the conditions for those steps may vary as desired in so far as the requirements such as component of the material or the coiling temperature for the hot rolled sheet, etc., are observed.
  • the amount of C for the present invention may be that contained in the ordinary low carbon cold rolled steel sheet. If it is desired to obtain lower carbon content for pursuing more excellent press formability, or lower bubbling or sagging, the molten steel may be degassed under vacuum conditionsor the material may be subjected to decarburization treatment at the time of annealing, whereby the above object can easily be accomplished.
  • the present invention it is advantageous to keep the N content in the sheet as low as possible, whereby the stabilization of the r value, the decrease of the strain aging property as well as the excellent press formability can be obtained.
  • the strain aging property it is possible to add such N-fixing elements as A], B, V and the like.
  • a steel sheet obtained by converter and subjected to the usual steps of casting, blooming and hot rolling was coiled at 700C to 730C to obtain a hot rolled coil, which was then allowed to stand in the air to the ordinary temperature.
  • This hot rolled sheet was further subjected to the cold rolling step to obtain the final thickness of 0.7mm.
  • the recrystalization annealing for 700C X 1 minute and the subsequent overaging treatment for 350C X 2 minutes were effected in the continuous annealing system and further the temper rolling was effected to the extent of 1 to 1.5%.
  • the table below shows the chemical compositions of the materials (a) and (b) of the invention (analysis of the product) and the properties of the steel sheet obtained. By way of comparison, the data of the steel plate having a large K value are also shown in the table.
  • the material of this invention to be com- (0.7mm thick) pared (a) (b) (0.7mm thick) C 0.04 0.04 0.04 Mn 0.18 0.17 0.33 Composition S 0.010 0.015 0.010 O 0.042 0.075 0.028 K 0.02 0.1 l 0.22 Coiling temperature C 700 to 720 670 to 680 530 to 550 Annealing (Contin- 700CX1min. 700CX1min. 700CXlm
  • Temper rolling(%) 1.0 to 1.5 1.0 to 1.5 1.0 to 1.5 1.0 to 1.5 a)
  • Yield point (kglmm 19.1 19.5 22.1
  • Elongation 44 42 r 1.60 1.5 1.12 C
  • C V 26.02 26.25 27.21
  • Erichsen test (mm) 10.8 10.8 10.3
  • box annealing with over-aging should read --box annealing or continuous annealing with overaging.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
US374390A 1972-06-30 1973-06-28 Method for manufacturing a steel for enameling Expired - Lifetime US3912549A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP6575272A JPS5319967B2 (enrdf_load_stackoverflow) 1972-06-30 1972-06-30

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US3912549A true US3912549A (en) 1975-10-14

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US (1) US3912549A (enrdf_load_stackoverflow)
JP (1) JPS5319967B2 (enrdf_load_stackoverflow)
DE (1) DE2333467A1 (enrdf_load_stackoverflow)
FR (1) FR2190924B2 (enrdf_load_stackoverflow)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4019929A (en) * 1974-06-24 1977-04-26 Nippon Kokan Kabushiki Kaisha Enameling cold rolled steel sheet with a high enamel adhesive property
US4062700A (en) * 1974-12-30 1977-12-13 Nippon Steel Corporation Method for producing a steel sheet with dual-phase structure composed of ferrite- and rapidly-cooled-transformed phases
US4313770A (en) * 1979-06-28 1982-02-02 Sumitomo Metal Industries, Ltd. Method of producing cold rolled steel strip having improved press formability and bake-hardenability
US4397699A (en) * 1980-05-27 1983-08-09 Nippon Steel Corporation Process for producing deep-drawing cold rolled steel strip by continuous annealing
US11236427B2 (en) 2017-12-06 2022-02-01 Polyvision Corporation Systems and methods for in-line thermal flattening and enameling of steel sheets

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60155386A (ja) * 1984-01-25 1985-08-15 大同特殊鋼株式会社 搬送移載装置
US4751850A (en) * 1984-04-03 1988-06-21 Shimano Industrial Company, Limited Speed change operating device for a bicycle

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2878151A (en) * 1954-11-19 1959-03-17 Armco Steel Corp Method for producing single-fire enameling stock devoid of fish-scaling and product thereof
US3183078A (en) * 1961-09-29 1965-05-11 Yawata Iron & Steel Co Vacuum process for producing a steel for nonageing enameling iron sheets
US3806376A (en) * 1969-12-30 1974-04-23 Nippon Steel Corp Method for producing low-carbon cold rolled steel sheet having excellent cold working properties and an apparatus for continuous treatment thereof

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2104987A1 (en) * 1970-09-14 1972-04-28 Nippon Kokan Kk Decarburisation annealed rimmed steel prodnimprovement
JPS559393B2 (enrdf_load_stackoverflow) * 1974-06-05 1980-03-10

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2878151A (en) * 1954-11-19 1959-03-17 Armco Steel Corp Method for producing single-fire enameling stock devoid of fish-scaling and product thereof
US3183078A (en) * 1961-09-29 1965-05-11 Yawata Iron & Steel Co Vacuum process for producing a steel for nonageing enameling iron sheets
US3806376A (en) * 1969-12-30 1974-04-23 Nippon Steel Corp Method for producing low-carbon cold rolled steel sheet having excellent cold working properties and an apparatus for continuous treatment thereof

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4019929A (en) * 1974-06-24 1977-04-26 Nippon Kokan Kabushiki Kaisha Enameling cold rolled steel sheet with a high enamel adhesive property
US4062700A (en) * 1974-12-30 1977-12-13 Nippon Steel Corporation Method for producing a steel sheet with dual-phase structure composed of ferrite- and rapidly-cooled-transformed phases
US4313770A (en) * 1979-06-28 1982-02-02 Sumitomo Metal Industries, Ltd. Method of producing cold rolled steel strip having improved press formability and bake-hardenability
US4397699A (en) * 1980-05-27 1983-08-09 Nippon Steel Corporation Process for producing deep-drawing cold rolled steel strip by continuous annealing
US11236427B2 (en) 2017-12-06 2022-02-01 Polyvision Corporation Systems and methods for in-line thermal flattening and enameling of steel sheets

Also Published As

Publication number Publication date
JPS4924829A (enrdf_load_stackoverflow) 1974-03-05
JPS5319967B2 (enrdf_load_stackoverflow) 1978-06-23
FR2190924A2 (enrdf_load_stackoverflow) 1974-02-01
FR2190924B2 (enrdf_load_stackoverflow) 1977-05-13
DE2333467A1 (de) 1974-01-31

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