US3876476A - Continuously cast slabs for grain oriented electrical steel sheet and method for producing said steel sheet - Google Patents

Continuously cast slabs for grain oriented electrical steel sheet and method for producing said steel sheet Download PDF

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Publication number
US3876476A
US3876476A US310261A US31026172A US3876476A US 3876476 A US3876476 A US 3876476A US 310261 A US310261 A US 310261A US 31026172 A US31026172 A US 31026172A US 3876476 A US3876476 A US 3876476A
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steel sheet
grain oriented
oriented electrical
continuously cast
electrical steel
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US310261A
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Hideo Matsuoka
Minoru Motoyoshi
Masaru Makino
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Nippon Steel Corp
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Nippon Steel Corp
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • 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
    • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
    • C21D8/1205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties involving a particular fabrication or treatment of ingot or slab

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  • ABSTRACT A continuously cast slab for producing grain oriented electrical steel sheets, comprising 0.025 0.060% of carbon, not less than 0.030% of manganese, not less than 0.010% of sulfur, 2.0 4.0% of silicon, not more than 0.005% of sol.aluminum, with the balance being iron and unavoidable impurities, and the ratio of SiO. /Al O being not more than 1.1.
  • Multifier c1 CONTINUOUSLY CAST SLABS FOR GRAIN ORIENTED ELECTRICAL STEEL SHEET AND METHOD FOR PRODUCING SAID STEEL SHEET The present invention relates to production of a grain oriented electrical steel sheet having good magnetic properties from a continuously cast slab having a specially adjusted composition.
  • a silicon steel is composed of grains having bodycentered cubic lattice, and it is well known that the three l axes in the mutually perpendicular edge direction can be easily magnetized. Also, in a grain oriented electrical steel sheet, the easily magnetizable direction of the l00 axis is arranged in parallel to the rolling direction of the steel sheet, and the (110) plane is arranged in parallel to the rolled surface. ln crystallography this is designated as (110) [001] orientation by the Miller indices.
  • the composing grains have a specific selected orientation, and the formation of such grains is attained by the so-called secondary recrystallization caused by selective growth of the primary recrystallization grains having the (110) [001] orientation through the final annealing of the cold rolled steel sheet of final thickness.
  • the grain oriented electric steel sheet as a soft magnetic material, is used chiefly for transformers and iron cores of generators, and must have good magnetization characteristics (relationship between the magnetic field strength and the magnetic flux density) and iron loss characteristics (relationship between the magnetic flux density and the iron loss) as the magnetic properties.
  • the magnetization characteristics depend on the degree of the magnetic flux density (generally expressed by B value-wb/m caused within the iron core with respect to a given magnetic field.
  • B can be obtained by a grain oriented magnetic steel sheet containing grains having a l00 axis along the rolling direction in a high proportion.
  • lron loss (generally represented by the value of W /50-W/kg-) is the energy loss consumed as heat energy of the iron core in a certain alternating magnetic field.
  • thedegree of iron loss is influenced by the plate thickness of the grain oriented magnetic steel sheet which composes the iron core, the amount of impurities, the specific resistance, the residual stress, etc., and it is also known that the influence of the magnetization characteristics is predominant.
  • Advantages of continuous casting include shortening of the production day thanks to the shortening of the production process, improved productivity by savings of labour, and technical advantages, such as, uniform chemical composition among individual slabs by uniformity of chemical composition in the casting direction.
  • impurities mainly sulfides
  • black band appears near the central portion in the plate thickness direction and its grain structure contains many columnar grains elongated in the plate thickness direction.
  • the fine dispersed precipitate for the secondary recrystallization is formed by a fine precipitation of impurities contained in the steel caused by the control of cooling rate during the hot rolling or by the heat treatments after the hot rolling, but prior to this precipitation treatment, it is necessary to dissolve these impurities during the slab heating.
  • the present invention has overcome the above difficulties in the production of grain oriented electrical steel sheet using solely MnS as the fine dispersed precipitate for the secondary recrystallization by continuous casting.
  • One of the objects of the present invention is to provide continuously cast slabs for grain oriented electrical steel sheets having excellent magnetic properties and to provide a method for producing the grain oriented electrical steel sheets from the continuously cast slab.
  • Another object of the present invention is to obtain grain oriented electrical steel sheets having excellent magnetic properties consistently using the continuously cast slabs.
  • the features of the present invention lie in a continuously cast slab for grain oriented electrical steel sheets, comprising 0.025 0.060% of carbon, not less than 0.030% of manganese, not less than 0.010% of sulfur,
  • the magnetic flux density (B,,) in the rolling direction after the final annealing reaches more than l.83 wb/m which is equal or better than the magnetic properties obtained by the ordinary ingot-making method.
  • FIGS. 1 and 2 are photographs showing continuously cast slabs.
  • FIG. 3 is a graph showing the relation between the oxygen contents in molten steel for continuous casting before deoxidization and the magnetic flux density (8 of the final product.
  • FIG. 4 is a graph showing the multiplier of Al use correlated to the oxygen contents in molten steel for continuous casting before deoxidization and the magnetic flux density of the final product
  • FIG. 5 is a graph showing the relation between the amount of Al used and the ratio of Si- O /AI O
  • the carbon content is limited to 0.025 to 0.060% for the following reasons.
  • silicon is contained in a similer level as in an ordinary grain oriented electrical steel sheet, and less than 2% of silicon increases iron loss while more than 4% of silicon embrittles the steel, thus causing difficulties in the cold rolling. Thus the silicon content is limited to 2 4%.
  • Manganese is defined as not less than 0.030% and sulfur is defined as not less than 0.010%.
  • the amount of MnS is not enough for forming the fine dispersed precipitate for the secondary recrystallization, and thus it is difficult to fully effect the secondary recrystallization.
  • manganese and sulfur are contained in too large amounts, dissolution of MnS which has precipitated in previous steps becomes difficult.
  • manganese is limited to not more than 0.075% and sulfur is limited to not more than 0.025%.
  • the improvement of the magnetization characteristics (B,,) can be attained by restricting the secondary recrystallization selectively grown from the primary recrystallization having the (110)[00l] orientation (so-called Goss orientation) at the time of final annealing and increasing the proportion of the grains having the (110)[00l] orientation.
  • the slabs obtained by the continuous casting method have a peculiar interior nature and have inferior uniformity in the chemical composition and the grain structure so that the magnetic properties of the final products often are inferior.
  • the materials produced by continuous casting are subjected to rapid cooling in an exceedingly flat mold having its width several times of its thickness so that columnar grains elongated from the slab surface in the thickness direction are predominant as shown in FIG. 1 and moreover the chemical components segregate in the thickness direction as shown in FIG. 2 so that a concentrated segregation portion commonly called as black band appears near the central portion in the thickness direction.
  • the columnar grains in the continuously cast slab as shown in FIG. I develop further in the slab heating step before the hot rolling, and this is more remarkable as the slab heating temperature reaches a high temperature more than l,350C for example.
  • the segregation portion near the center in the thickness of the continuously cast slab makes it difficult to dissolve MnS in the subsequent slab reheating step, which MnS is used in the present invention as the fine dispersed precipitate for the secondary recrystallization, and also makes it very difficult to obtain uniform distribution of [Mn] and [S].
  • the slab heating temperature may be increased (for example more than l,350C),
  • MnS precipitate in a form effective for the secondary recrystallization in the hot rolling stage or the heat treating step of the hot rolled sheet, because it is very difficult to obtain uniform distribution of [Mn] and [S] due to unsatisfactory dissolution of MnS of the concentrated segregation portion in case of the material produced by continuous casting.
  • the present inventors have succeeded in obtaining a grain oriented electrical steel sheet having excellent magnetic properties by subjecting molten steel to a special deoxidization treatment with Al before continuous casting so as to convert the precipitation form of MnS into a form effective for the secondary recrystallization and in the present invention MnS is used solely as the fine dispersed precipitate for the secondary recrystallization.
  • MnS is solely used as the fine dispersed precipitate so that it is not necessary to intentionally add Al which forms a nitride (AlN), and Al is not added as deoxidizer because if Al is used as deoxidizer it is nec essary to severely control the Al addition in order to control the amount of sol.Al after deoxidization by Al and Si in combination.
  • AlN nitride
  • the oxygen content in the molten steel before deoxidization is restricted and Al is intentionally added to the molten steel for deoxidization in a range which is not enough for forming AlN and for it to form a combined dispersed precipitate with MnS.
  • FIG. 3 shows the relation between the oxygen content in the continuous casting molten steel containing about 3% Si before deoxidization and the magnetic flux density (B of the final products (0.30 mm and 0.35 mm thickness).
  • the amount of Al used for the deoxidization is [oxygen(%) 8-15] kg /ton (molten steel).
  • FIG. 4 shows the relation between the multiplier (a) for Al use correlated with the oxygen content (0.05 0.10%) in the continuous casting molten steel before deoxidization and the magnetic flux density (B of the final products (0.30 mm and 0.35 mm thickness).
  • Al is used in an amount not less than [oxygen(%) X 8]kg/ton, and its upper limit is limited to such .an amount that sol.Al is contained less than 0.005%.
  • the upper limit of Al to be used is about [oxygen(%) X 15 ]kg/ton.
  • the most preferable range is one which corresponds to the so
  • the present inventors investigated the relation between the amount of Al used and impurities contained in steel materials produced by continuous casting in order to determine the effects of Al deoxidization on improvement of the magnetic flux density.
  • the results are shown in FIG. 5. It is understood from the results that as the amount of Al used increases, the ratio of Si- O /AI O tends to decrease, and that desired results are obtained in the present invention when the ratio of Si- O /Al O is not more than 1.1. Thus it is also understood from the results shown in FIG. 5 that the ratio of SiO /AI O and therefore the precipitation form of MnS have a large influence on the magnetic properties (particularly the magnetization characteristics which is are related to the secondary recrystallization).
  • the deoxidization method of the present invention enhances the effect of the-MnS which is used as the fine dispersed precipitate for the secondary recrystallization. It has thereby become possible to produce a grain oriented electrical steel sheet having excellent magnetic properties by continuous casting.
  • the slabs A and E produced according to the present invention the slab B has an oxygen content before deoxidation outside the range of the present invention, the slab C has an aluminum content outside the range of the present invention, the slab D is one obtained by a conventional method using almost no Al, and the slab F has a carbon content outside the range of the present invention.
  • the materials A and E of the present invention give magnetic properties with higher stability as compared with the materials B, C, D and F.
  • the slabs A, B, C. D. E and F were heated at 1.300C for 3 hours. hot rolled to a thickness of 2.3 mm and then cold rolled to a thickness of 0.30 mm by an ordinary two-pass cold rolling method to obtain the final products.
  • a continuously cast slab for producing grain oriented electrical steel sheets consisting essentially of 0.025 to 0.060 carbon, not less than 0.030% manganese, not less than 0.010% sulfur, 2.0 to 4.0% silicon, not more than 0.12% oxygen, not more than 0.005% sol. aluminum, said slab having been deoxidized by adding aluminum in an amount of not less than (oxygen 8-15) kg/ton, with the balance being iron and unavoidable impurities and the ratio of SiO /Al- O being not more than 1.1.
  • sol.aluminum is 0.002 0.005%.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Metallurgy (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Thermal Sciences (AREA)
  • Electromagnetism (AREA)
  • Manufacturing Of Steel Electrode Plates (AREA)
  • Soft Magnetic Materials (AREA)
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US310261A 1971-12-03 1972-11-29 Continuously cast slabs for grain oriented electrical steel sheet and method for producing said steel sheet Expired - Lifetime US3876476A (en)

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JP46097704A JPS5218647B2 (pt) 1971-12-03 1971-12-03

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JP (1) JPS5218647B2 (pt)
BE (1) BE792173A (pt)
BR (1) BR7208494D0 (pt)
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IT (1) IT971507B (pt)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4014717A (en) * 1974-10-09 1977-03-29 Centro Sperimentale, Metallurgico S.P.A. Method for the production of high-permeability magnetic steel
US4092178A (en) * 1974-12-11 1978-05-30 Nippon Steel Corporation Process for producing a steel having excellent strength and toughness
US4115160A (en) * 1977-06-16 1978-09-19 Allegheny Ludlum Industries, Inc. Electromagnetic silicon steel from thin castings
US4116729A (en) * 1977-09-09 1978-09-26 Nippon Steel Corporation Method for treating continuously cast steel slabs
US4202711A (en) * 1978-10-18 1980-05-13 Armco, Incl. Process for producing oriented silicon iron from strand cast slabs
US4280837A (en) * 1979-10-31 1981-07-28 Nippon Steel Corporation Method for continuously casting slab for manufacturing grain-oriented electrical steel sheet and strip
WO1993013236A1 (en) * 1991-12-26 1993-07-08 Pohang Iron & Steel Co., Ltd. Process for manufacturing high magnetic flux density grain oriented electrical steel sheet having superior magnetic properties

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS585970B2 (ja) * 1979-05-16 1983-02-02 新日本製鐵株式会社 線状細粒のない一方向性珪素鋼板の製造方法
JPH0453066Y2 (pt) * 1986-12-24 1992-12-14

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3671337A (en) * 1969-02-21 1972-06-20 Nippon Steel Corp Process for producing grain oriented electromagnetic steel sheets having excellent magnetic characteristics

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB945581A (en) * 1961-01-27 1964-01-02 Westinghouse Electric Corp Cube textured iron silicon magnetic alloy sheets and process for making the same
AU1221270A (en) * 1969-03-14 1971-09-09 Armco Steel Corporation Process forthe production of oriented silicon iron by vacuum degassing and continuous casting

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3671337A (en) * 1969-02-21 1972-06-20 Nippon Steel Corp Process for producing grain oriented electromagnetic steel sheets having excellent magnetic characteristics

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4014717A (en) * 1974-10-09 1977-03-29 Centro Sperimentale, Metallurgico S.P.A. Method for the production of high-permeability magnetic steel
US4092178A (en) * 1974-12-11 1978-05-30 Nippon Steel Corporation Process for producing a steel having excellent strength and toughness
US4115160A (en) * 1977-06-16 1978-09-19 Allegheny Ludlum Industries, Inc. Electromagnetic silicon steel from thin castings
US4116729A (en) * 1977-09-09 1978-09-26 Nippon Steel Corporation Method for treating continuously cast steel slabs
US4202711A (en) * 1978-10-18 1980-05-13 Armco, Incl. Process for producing oriented silicon iron from strand cast slabs
US4280837A (en) * 1979-10-31 1981-07-28 Nippon Steel Corporation Method for continuously casting slab for manufacturing grain-oriented electrical steel sheet and strip
WO1993013236A1 (en) * 1991-12-26 1993-07-08 Pohang Iron & Steel Co., Ltd. Process for manufacturing high magnetic flux density grain oriented electrical steel sheet having superior magnetic properties

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BR7208494D0 (pt) 1973-08-30
DE2259199C3 (de) 1982-07-22
IT971507B (it) 1974-05-10
JPS4861319A (pt) 1973-08-28
JPS5218647B2 (pt) 1977-05-23
DE2259199A1 (de) 1973-06-14
BE792173A (fr) 1973-03-30
DE2259199B2 (de) 1978-05-03

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