US3872704A - Method for manufacturing grain-oriented electrical steel sheet and strip in combination with continuous casting - Google Patents

Method for manufacturing grain-oriented electrical steel sheet and strip in combination with continuous casting Download PDF

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Publication number
US3872704A
US3872704A US314496A US31449672A US3872704A US 3872704 A US3872704 A US 3872704A US 314496 A US314496 A US 314496A US 31449672 A US31449672 A US 31449672A US 3872704 A US3872704 A US 3872704A
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United States
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percent
slab
strip
steel sheet
oriented electrical
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US314496A
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English (en)
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Tatsuo Ohya
Eizo Sakuma
Minoru Motoyoshi
Masafumi Okamoto
Kiyoshi Tanaka
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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
    • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
    • C21D8/1216—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the working step(s) being of interest
    • C21D8/1222—Hot rolling

Definitions

  • the magnetization characteristic (the relation between the magnetic field intensity and the magnetic flux density) and the iron loss characteristic (the relation between the magnetic flux density and the iron loss) are excellent. It' is re quired that the magnetic flux density as a magnetization characteristic (expressed generally by the B value) is high, and the iron loss (expressed generally by W value) is low.
  • the value can also be reduced by improving the magnetization characteristic, i.e., B Steel sheet and strip having high B value possess a favourable iron loss particularly in the high magnetic flux density region.
  • improving the magnetization characteris tic is effective not only for the reduction of iron loss, but also to minimize the size of various electrical instruments, such as, transformers, by lightening the weight of iron core used therefor.
  • the method for manufacturing steel has been changing rapidly from the conventional ingot making which has been replaced more and more in recent years to continuous casting.
  • the continuous casting method is advantageous since the yield is improved, and the blooming step is omitted.
  • the method is particularly useful in the manufacture of high class steels.
  • Steel plates manufactured by continuous casting have also possess superior surface shape and appearance in general and uniformity of the chemical composition in the casting direction.
  • the macrostructure of a continuously casted slab while the surface and core parts consist of granular grains, a greater part of the intermediate portion is formed of columnar grains, and moreover, a dense segregation zone of sulfur, called black band, exists at the central part in the direction of the slab thickness.
  • the columnar crystals in the continuously casted slab for use as grain-oriented electrical steel sheet and strip grow abnormally when the temperature is high (i.e., above 1350C) in heating the slab for hot rolling, give an abnormal structure in the stage of primary recrystallization annealing after the hot and cold rolling, and change to so called fibrous fine grains in the final secondary recrystallization annealing, thus deteriorating the magnetic characteristics.
  • the present inventors have succeeded in manufacturing grain-oriented electrical steel sheet and strip by utilizing continuous casting, in which MnS is utilized as effective fine dispersed particles for the development of the secondary recrystallization grain. This results in the production of grain-oriented electrical steel sheet and strip having consistently excellent magnetic characteristics by assuring that the MnS is dissolved in the steel as a solid solution sufficiently in the heating stage of the slab and is precipitated effectively in the hot rolling stage of the material.
  • the present invention provides a method for manufacturing grain-oriented electrical steel sheet and strip having stabilized high magnetic characteristics in the rolling direction, characterized in that a continuously cast slab containing 0.005 0.06 percent of C, not
  • more than 4.0 percent of Si, 0.030 0.090 percent of Mn and 0.010 0.030 percent of S is, after heating to a temperature from 1250C to l350C, hot rolled continuously under the condition that the material is kept for 30 200 seconds at a temperature between 11200C and 950C, and then the material is cold rolled and annealed.
  • the two prior arts relate to controlling MnS in the solidification of molten steel, and, as for the method of controlling MnS in the slab and other already solidified 3 materials, only the method of controlling the slab heating temperature is found in the prior art.
  • the present invention is to control the behavior of MnS by cooling the continuously cast slab slowly in the course of hot rolling, and this is a quite different technical idea from the conventional art.
  • the starting material for the manufacture of electrical steel sheet and strip in this invention is a steel slab, for whose manufacture, molten steel which is smelted by a known steel making method, for instance, in a converter or an electric furnace, is solidified by a continuous casting method.
  • Mn 0.030 0.090% and S decide the amount of MnS as fine dispersed particles which is important for the grain growth in the secondary crystallization.
  • fine dispersed particles in this invention consists chiefly of MnS, a proper amount of AlN and similar compounds containing Se, Te, B and the like may also be added as the constituents in the dispersed particles. 7
  • Si is effective to reduce the iron loss in electrical steel sheet and strip.
  • the amount of Si in the present invention is similar to the content thereof in usual grain-oriented electrical steel sheet and strip. As cracks are formed in the cold rolling when the amount is larger than 4.0 percent, the amount of Si is defined as less than 4.0percent.
  • the amount of C is defined as 0.0050 0.060percent. When the amount is larger than this range, much time is required for the decarburization in the subsequent stage and it is not economical. If below this range, the secondary recrystallization proceeds with difficulty, and fine crystal grains are apt to be formed in the final product.
  • MnS as the dispersed precipitate in this invention is already formed in the continuously cast slab before the slab is heated for the hot rolling, as MnS in this state is not uniform in its dispersion and has a relatively large size, it is necessary to dissolve the MnS in the matrix as a solid solution in the slab heating furnace.
  • the problem of columnar grains exists in the continuously cast slab as above-mentioned, and, when such a slab is heated at a higher temperature (above l350C), the grains grow abnormally to deteriorate the magnetic characteristics of the final product. Therefore, the slab heating should be carried out at a relatively low temperature.
  • the amounts of Mn and S are defined as abovementioned in this invention in order to dissolve the MnS in matrix as a solid solution sufficiently in the temperature range where the abnormal growth of columnar grains does not take place.
  • the slab heating temperature necessary to satisfy the condition depends on the amounts of Mn and S, and there exists a suitable temperature range defined in general by [Mn%] X [8%].
  • the temperature range corresponding to the amounts of Mn and S in the present invention lies between l250 l350C, where MnS can be dissolved sufficiently in the steel as a solid solution without the ab normal growth of columnar grains.
  • MnS once dissolved in the steel as a solid solution, is precipitated at a definite temperature range, differing somewhat depending on the amounts of Mn and S, in the course of the continuous hot rolling.
  • the dispersed particles As effective fine dispersed particles for the development of secondary recrystallization grains having (1 10)[00l] orientation, it is necessary that the dispersed particles be of a size less than 0.1;1. and are dispersed uniformly with a high distribution density. It is the feature of this invention that the precipitation of MnS as above-mentioned, having a fine in particle size and dispersed uniformly with a high distribution density, is performed by utilizing the continuous hot rolling process.
  • the temperature range of precipitating effective MnS is 1200 930C, and the object is attained by keeping the material for 30 200 seconds at this temperature range.
  • FIG. 1 is a graph showing the relation between the average holding temperature of the material in the continuous hot rolling process and B
  • FIG. 2 is a graph showing the relation between the holding period from l200to 950C and B
  • FIG. 3 is a graph showing some examples of the cooling patterns.
  • FIG. 1 shows the relation between the average holding temperature of the material and the magnetic flux density B when the material is kept for a definite period in the range before the (45 sec.) finish rolling in the continuous hot rolling process of a slab after heating the slab at a temperature 1250 1350C.
  • a high magnetic flux density B is obtained when the holding temperature is in the range of 1200 950C. This is because the effective MnS is precipitated only when the holding temperature lies in the range of 1200 950C.
  • FIG. 2 shows the relation between the holding period of the material in the temperature range from l200 to 980C when the slab heated at a temperature 1250 1350C is cooled slowly in said temperature range before the finish rolling in the continuous hot rolling.
  • a high magnetic flux density 8 can be obtained when the holding period is 30 200 seconds.
  • the holding period is less than 30 seconds, the precipitation of effective MnS is insufficient, and on the other hand, when the holding period exceeds 200 seconds, the MnS precipitate grows coarse and begins to aggregate. In both cases, the precipitation of MnS effective for the development of the secondary recrystallization grains having (110)[001] orientation can not be obtained.
  • the condition of continuous hot rolling process in this invention is defined as keeping the slab for 30 200 seconds in the temperature range l200 -950C in the continuous hot rolling.
  • the slow cooling may be extended to the hot finish rolling process when a sufficiently slow cooling can also be performed in the hot finish rolling.
  • a sufficiently slow cooling can also be performed in the hot finish rolling.
  • FIG. 3 shows some examples of the cooling pattern in such a hot rolling line.
  • a distinct bend point (a) in each of the curves represent the state before the finish rolling stand.
  • the finish rolling is done from about 1200C
  • the material is cooled slowly from 1200to 950C and the finish rolling is done from 950C
  • the material is kept at a constant temperature in the range 1200 950C and the finish rolling is done above 950C
  • the finish rolling is done from about 950C without any slow cooling or a constant temperature treatment.
  • curve (D) while a temperature range 1200 950C exists before the finish rolling, as the holding period is short, the object of the present invention can not be achieved.
  • the curve (D) shows a typical cooling pattern heretofore.
  • such means for instance, as controlling the water amount in descaling or in roll cooling, the revolution number of the roll or the number of pass times in the course of rough rolling of the slab taken out from the heating furnace, reducing the reduction of the rolling material in said stage, and increasing the thickness of the slab manufactured by the continuous casting, or the combination of these means may be adopted.
  • a hot rolled steel sheet containing proper MnS obtained in this way is cold rolled more than once, and subjected to a primary recrystallization-decarburization annealing and finally a finish annealing to obtain the final product.
  • Example 2 The slow cooling was done in a similar way as in Example 1. These hot rolled sheets were cold rolled two times (the reduction in the secondary rolling was percent) inserting an intermediate annealing for 3 minutes at 840C to obtain final products 0.30'mm in thickness, decarburization annealed for 3 minutes at 850C in moist H and finally annealed for 20 hours at 1170C in H Magnetic characteristics of the product in the rolling direction were as shown in Table 2.
  • grain-oriented electrical steel sheet and strip having quite excellent magnetic characteristics can be manufactured by utilizing a continuous casting method according to the present invention, and possess great industrial merit.
  • a method for manufacturing grain-oriented electrical steel and strip having excellent and stabilized magnetic characteristics in the rolling direction by continuous casting comprising heating a continuous cast steel slab containing 0.005 0.060 percent of carbon, not more than 4.0 percent of silicon, 0.030 0.090 percent of manganese and 0.010 0.030 percent of sulfur to a temperature from l250 to 1350C, hot rolling the slab continuously under the condition that the material is kept for 30 200 seconds in the temperature range between 1200 and 950C, and then cold rolling and annealing the sheet.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Thermal Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Electromagnetism (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing Of Steel Electrode Plates (AREA)
  • Continuous Casting (AREA)
  • Soft Magnetic Materials (AREA)
  • Metal Rolling (AREA)
US314496A 1971-12-24 1972-12-12 Method for manufacturing grain-oriented electrical steel sheet and strip in combination with continuous casting Expired - Lifetime US3872704A (en)

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JP47001413A JPS5032059B2 (de) 1971-12-24 1971-12-24

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US (1) US3872704A (de)
JP (1) JPS5032059B2 (de)
BR (1) BR7209022D0 (de)
DE (1) DE2262869B2 (de)
IT (1) IT972779B (de)

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3930906A (en) * 1974-02-28 1976-01-06 Kawasaki Steel Corporation Method for forming an insulating glass film on a grain-oriented silicon steel sheet having a high magnetic induction
US3976517A (en) * 1975-07-15 1976-08-24 Allegheny Ludlum Industries, Inc. Processing for grain-oriented silicon steel
US4014717A (en) * 1974-10-09 1977-03-29 Centro Sperimentale, Metallurgico S.P.A. Method for the production of high-permeability magnetic steel
FR2361182A1 (fr) * 1976-08-10 1978-03-10 Nippon Steel Corp Brame obtenue par coulee continue pour produire des toles d'acier de qualite electrique a grains orientes ayant d'excellentes proprietes magnetiques
US4116729A (en) * 1977-09-09 1978-09-26 Nippon Steel Corporation Method for treating continuously cast steel slabs
US4118255A (en) * 1975-08-01 1978-10-03 Centro Sperimentale Metallurgico S.P.A Process for the production of a silicon steel strip with high magnetic characteristics
US4302257A (en) * 1978-03-11 1981-11-24 Nippon Steel Corporation Process for producing a grain-oriented silicon steel sheet
US4372719A (en) * 1981-01-21 1983-02-08 The Continental Group, Inc. Annealing of end rim
FR2511046A1 (fr) * 1981-08-05 1983-02-11 Nippon Steel Corp Procede pour la production de tole ou de bande en acier electromagnetique a grain oriente et tole ou bande ainsi obtenue
US4478653A (en) * 1983-03-10 1984-10-23 Armco Inc. Process for producing grain-oriented silicon steel
US4702780A (en) * 1983-06-20 1987-10-27 Kawasaki Steel Corporation Process for producing a grain oriented silicon steel sheet excellent in surface properties and magnetic characteristics
WO1998028452A1 (en) * 1996-12-24 1998-07-02 Acciai Speciali Terni S.P.A. Process for the production of oriented-grain electrical steel sheet with high magnetic characteristics
WO1998028451A1 (en) * 1996-12-24 1998-07-02 Acciai Speciali Terni S.P.A. Process for the production of grain oriented silicon steel sheet
WO1998041660A1 (en) * 1997-03-14 1998-09-24 Acciai Speciali Terni S.P.A. Process for the inhibition control in the production of grain-oriented electrical sheets
US20090301151A1 (en) * 2006-04-24 2009-12-10 Sumitomo Metal Industries, Ltd. lubricant composition for hot metal working and method of hot metal working using the same
US20090301157A1 (en) * 2006-06-26 2009-12-10 Ingo Schuster Method of and apparatus for hot rolling a thin silicon-steel workpiece into sheet steel

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5483467U (de) * 1977-11-22 1979-06-13
JPS59208020A (ja) * 1983-05-12 1984-11-26 Nippon Steel Corp 低鉄損一方向性電磁鋼板の製造方法
WO1986003784A1 (en) * 1983-06-20 1986-07-03 Kawasaki Steel Corporation Method of manufacturing unidirectional silicon steel slab having excellent surface and magnetic properties
US4950336A (en) * 1988-06-24 1990-08-21 Nippon Steel Corporation Method of producing non-oriented magnetic steel heavy plate having high magnetic flux density
CN108393455A (zh) * 2018-01-25 2018-08-14 石家庄钢铁有限责任公司 控制合金钢大方坯中MnS夹杂物尺寸的连铸方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2867557A (en) * 1956-08-02 1959-01-06 Allegheny Ludlum Steel Method of producing silicon steel strip
US3061486A (en) * 1957-12-30 1962-10-30 Armco Steel Corp Non-directional oriented silicon-iron
US3069299A (en) * 1956-12-31 1962-12-18 Gen Electric Process for producing magnetic material

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2867557A (en) * 1956-08-02 1959-01-06 Allegheny Ludlum Steel Method of producing silicon steel strip
US3069299A (en) * 1956-12-31 1962-12-18 Gen Electric Process for producing magnetic material
US3061486A (en) * 1957-12-30 1962-10-30 Armco Steel Corp Non-directional oriented silicon-iron

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3930906A (en) * 1974-02-28 1976-01-06 Kawasaki Steel Corporation Method for forming an insulating glass film on a grain-oriented silicon steel sheet having a high magnetic induction
US4014717A (en) * 1974-10-09 1977-03-29 Centro Sperimentale, Metallurgico S.P.A. Method for the production of high-permeability magnetic steel
US3976517A (en) * 1975-07-15 1976-08-24 Allegheny Ludlum Industries, Inc. Processing for grain-oriented silicon steel
US4118255A (en) * 1975-08-01 1978-10-03 Centro Sperimentale Metallurgico S.P.A Process for the production of a silicon steel strip with high magnetic characteristics
FR2361182A1 (fr) * 1976-08-10 1978-03-10 Nippon Steel Corp Brame obtenue par coulee continue pour produire des toles d'acier de qualite electrique a grains orientes ayant d'excellentes proprietes magnetiques
US4116729A (en) * 1977-09-09 1978-09-26 Nippon Steel Corporation Method for treating continuously cast steel slabs
US4302257A (en) * 1978-03-11 1981-11-24 Nippon Steel Corporation Process for producing a grain-oriented silicon steel sheet
US4372719A (en) * 1981-01-21 1983-02-08 The Continental Group, Inc. Annealing of end rim
FR2511046A1 (fr) * 1981-08-05 1983-02-11 Nippon Steel Corp Procede pour la production de tole ou de bande en acier electromagnetique a grain oriente et tole ou bande ainsi obtenue
US4493739A (en) * 1981-08-05 1985-01-15 Nippon Steel Corporation Process for producing a grain-oriented electromagnetic steel sheet or strip having a low watt loss and a grain-oriented electromagnetic steel strip having uniform magnetic properties
US4478653A (en) * 1983-03-10 1984-10-23 Armco Inc. Process for producing grain-oriented silicon steel
US4702780A (en) * 1983-06-20 1987-10-27 Kawasaki Steel Corporation Process for producing a grain oriented silicon steel sheet excellent in surface properties and magnetic characteristics
WO1998028452A1 (en) * 1996-12-24 1998-07-02 Acciai Speciali Terni S.P.A. Process for the production of oriented-grain electrical steel sheet with high magnetic characteristics
WO1998028451A1 (en) * 1996-12-24 1998-07-02 Acciai Speciali Terni S.P.A. Process for the production of grain oriented silicon steel sheet
WO1998041660A1 (en) * 1997-03-14 1998-09-24 Acciai Speciali Terni S.P.A. Process for the inhibition control in the production of grain-oriented electrical sheets
US20090301151A1 (en) * 2006-04-24 2009-12-10 Sumitomo Metal Industries, Ltd. lubricant composition for hot metal working and method of hot metal working using the same
US8863564B2 (en) * 2006-04-24 2014-10-21 Sumitomo Metal Industries, Ltd. Lubricant composition for hot metal working and method of hot metal working using the same
US20090301157A1 (en) * 2006-06-26 2009-12-10 Ingo Schuster Method of and apparatus for hot rolling a thin silicon-steel workpiece into sheet steel
US8408035B2 (en) * 2006-06-26 2013-04-02 Sms Siemag Ag Method of and apparatus for hot rolling a thin silicon-steel workpiece into sheet steel

Also Published As

Publication number Publication date
BR7209022D0 (pt) 1973-08-30
IT972779B (it) 1974-05-31
DE2262869B2 (de) 1975-08-28
JPS5032059B2 (de) 1975-10-17
JPS4869720A (de) 1973-09-21
DE2262869A1 (de) 1973-07-12

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