US3908432A - Process for producing a high magnetic flux density grain-oriented electrical steel sheet - Google Patents

Process for producing a high magnetic flux density grain-oriented electrical steel sheet Download PDF

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Publication number
US3908432A
US3908432A US451231A US45123174A US3908432A US 3908432 A US3908432 A US 3908432A US 451231 A US451231 A US 451231A US 45123174 A US45123174 A US 45123174A US 3908432 A US3908432 A US 3908432A
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flux density
magnetic flux
cold rolling
steel sheet
electrical steel
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US451231A
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Tadashi Ichiyama
Takashi Sato
Tsuyoshi Kikuchi
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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
    • C21D8/1216—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
    • C21D8/1233—Cold rolling

Definitions

  • the present invention relates to commercial production of grain-oriented electrical steel sheets having a very high degree of integration of the so-called Goss structure having the magnetizable axis 100 along the rolling direction of the sheet and the (1 l) plane in the surface of the steel sheet.
  • Grain-oriented electrical steel sheet has been used mainly for iron cores for electrical appliances such as, transformers and other, wherein good excitation characteristics and good watt loss properties are required.
  • the excitation characteristic is expressed by the value of the magnetic flux density in a magnetic field of 800A/m, and the watt loss properties are expressed by the electricity loss at a magnetic flux density of 17 K Gauss.
  • the hot rolled steel sheet obtained from the ingot is subjected to a cold rolling process including a final cold rolling step of more than 80% reduction so as to produce a high magnetic flux density grain-oriented electrical steel sheet having B characteristics of more than 1.85 wb/m
  • the present invention relates to improvements of the above methods disclosed in the Japanese Patent Applications Sho 45-92277 and Sho 46-82442. Namely, the present invention defines additional conditions for the constituent elements added in the starting materials, and by these additional conditions, the present inventors have succeeded in improving the excitation and watt loss characteristics and in reducing fluctuation in the excitation characteristics of the final products.
  • FIG. I shows the relation between the sulfur contents and the excitation characteristics in a 3% silicon steel containing one of four elements from the group of arsenic, bismuth, lead and antimony, in addition to selenium in case of the reduction of not less than 70% in the final cold rolling step.
  • FIG. 2 shows similarly the relation between the sulfur contents and the B values when the final cold rolling step is performed at a reduction rate between 50 and 60%.
  • FIG. 1 the values of magnetic flux density B at a 'magnetic field of 800A/m are plotted against the sulfur than 0.01%, the B value becomes remarkably high and the fluctuation is also improved.
  • a special treatment is applied, a normal sulfur content in the steel ingot is usually between 0.015 and 0.025%. Therefore, in order to maintain the sulfur content to not more than 0.01% and obtain this remarkable improvement of the magnetic properties, it is necessary to lower the sulfur content by using special methods, such as, the rotary kiln method, the DM converter method and the shaking ladle method.
  • FIG. 2 the relation between the sulfur contents and the value of the magnetic flux density B when the reduction of the final cold rolling step is between 50 and 60% which is a normal reduction in the production of grain-oriented electrical steel sheets is shown. It is understood from FIG. 2 that the lowering of the sulfur content does not improve the magnetic flux density value, but rather increases the fluctuation of the value. This means that the new additionalcondition of the sulfur content among the constituent elements is effective when the reduction of the final cold rolling step is higher than the normal reduction of 50 to 60%.
  • the lowering of the sulfur content to not more than 0.01% improves the B characteristics of the magnetic flux density not only in the case of the combination addition of one of arsenic, bismuth, lead, and antimony with selenium, but also in the case of the combination addition of two or more of arsenic, bismuth, lead and antimony with selenium as disclosed in Japanese Patent Application Sho 46-82442.
  • Sulfur not more than 0.01% and Selenium 0.01 to 0.1%, with one element selected from the group of Arsenic 0.01% to 0.15%, Bithmus 0.02 to 0.3%, Lead 0.02 to 0.3%, and Antimony 0.02 to 0.2%.
  • the total amount should be between 0.02 and 0.5%, with the balance being iron and traces of impurities which are harmless to the magnetic properties.
  • the reasons for the above limitations of the various elements in the steel are as follows.
  • the silicon content is less than 2.5%, the a 'y transformation takes place irrespective of the carbon content whatsoever, so that growth of the secondary recrystallization grains take place during the final annealing which is normally done at a temperature not lower than 1000C.
  • silicon contents of more than 4.0% tend to cause crackings due to embrittlement during the cold rolling.
  • the silicon content is defined to 2.5 to 4.0% in the present invention.
  • Carbon is necessary for promoting the presence of a precipitated dispersion containing arsenic, bismuth, lead or antimony, and when the total amount of the elements constituting the precipitated dispersion is small, the carbon content may be in the higher side in the range and when the total amount is large, it may be in the lower side. 7
  • the excitation and watt loss characteristics of a grain-oriented electrical steel sheet depend mainly on the integration degree of the Goss structure formed by the secondary recrystallization which takes place during the final annealing.
  • a higher degree of the Goss structure assures better excitation and watt loss characteristics.
  • the reduction in the final cold rolling step is higher than the normal reduction of 50 to 60% and that the dispersion which shows special thermal behavior near the recrystallization temperature is utilized.
  • the combined addition of arsenic, bismuth, lead and antimony with selenium is effective as disclosed in Japanese Patent Applications Sho 45-92277 and Sho 46-82442. But in this case, sulfur, such as, MnS, which forms dispersion showing a different thermal behavior is harmful.
  • silicon steel ingots having a chemical composition falling within the above defined range are produced by a conventional method and hot rolledinto hot rolled steel sheets of 1.5 to 5.0 mm thickness.
  • the magnetic properties of the final products are considerably improved when the steel material is retained for 60 to 360 seconds within a temperature range of l200 to 850C in the course of the continuous hot rolling step.
  • the hot rolled steel sheet, after acid pickling, is subjected one time or more than two times to the cold rolling step in such a-manner that the reduction of the final cold rolling is not less than 70%.
  • the sheet when the sheet is subjected more than two times to the cold rolling step, the sheet is subjected to an intermediate annealing for l to 30 minutes at a temperature between 750 and 1200C in a neutral or reducing gas between the cold rollings.
  • the final sheet thickness is to be obtained by a single cold rolling step, it is desirable to subject the hot rolled steel sheet to a preliminary annealing for l to 30 minutes at a temperature between 750 and l200C in a neutral or reducing gas prior to the cold rolling.
  • the reason for defining the reduction of the final cold rolling as not less than 70% is to obtain a high magnetic flux density B of more than 1.85 wb/m
  • a reduction rate of not less than 60% is enough due to the considerably improved level of the magnetic properties by the improvement of the hot rolling conditions as described above.
  • the steel sheet which has been reduced into the final thickness by the cold rolling is subjected to a short-time annealing by a conventional method for the purpose of decarburization and primary recrystallization.
  • the sheet is annealed in a gas mixture of wet hydrogen and nitrogen at a temperature between 800 and 850C for a few minutes.
  • the sheet is annealed in a reducing gas at a temperature of more than 1000C, preferably more than ll00C, for more five hours.
  • elements harmful to the watt loss characteristics, such as, carbon, selenium, and the remaining sulfur are removed and the secondary recrystallization proceeds so that a grain-oriented electrical steel sheet having very high magnetic flux density is obtained in a consistent and stable manner.
  • EXAMPLE 1 A silicon steel ingot containing 0.038% of carbon, 2.98% of silicon, 0.006% of sulfur, 0.03% of selenium, and 0.1% of arsenic was broken down into 200 mm thick slabs. The slabs were heated to l250-"-C and then subjected to continuous hot rolling to obtain hot rolled steel coils of 2.3 mm thickness. During the cooling step of the above hot rolling, adjustments were made so as to maintain the steel coils in a temperature range of l200 to 850C for 200 seconds. The hot rolled steel coils were acid pickled and some of them was subjected to preliminary annealing at 900C for 5 minutes and the remainder were not subjected to the preliminary annealing. Then all of the coils were reduced to 0.30 mm thickness by a single-step cold rolling and subjected to decarburization annealing and finishing high temperature annealing.
  • the magnetic properties along the rolling direction of the products thus obtained are as follows.
  • EXAMPLE 2 Silicon steel ingot containing 0.045% of carbon, 3.01% of silicon, 0.004% of sulfur, 0.05% of selenium and 0.05% of arsenic was broken down into slabs of 200 mm thickness. The slabs were heated to 1300C and subjected to continuous hot rolling to obtain hot rolled steel coils of 2.3 mm thickness. During the cooling step, the hot rolling adjustments were made so as to maintain the steel coils in a temperature range of l200 to 850C for 300 seconds. The thus obtained steel coils were acid pickled, cold rolled to an intermediate thickness of 1 mm, subjected to intermediate annealing at 850C for 5 minutes in hydrogen stream and then secondary cold rolling to obtain the final thickness of 0.30
  • the cold rolled steel sheet thus obtained was subjected to decarburization annealing and finishing high temperature annealing.
  • the magnetic properties along the rolling direction of the product are as follows.
  • u w l'llbll carbon 2.5 to 4.0% of silicon, 0.01 to 0.10% of selenium and one of an element selected from the group consisting of 0.01 to 0.15% of arsenic, 0.02 to 0.3% of bismuth, 0.02 to 0.3% of lead, and 0.02 to 0.2% of antimony with a sulfur content not more than 0.01% to cold rolling in which the reduction of the final cold rolling step is not less than then decarburization and final annealing.
  • the silicon steel ingot contains two or more than two of an element selected from the group consisting of arsenic, bismuth, lead and antimony in a total amount of 0.02 to 0.5%.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Manufacturing & Machinery (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Manufacturing Of Steel Electrode Plates (AREA)
  • Soft Magnetic Materials (AREA)
US451231A 1973-03-20 1974-03-14 Process for producing a high magnetic flux density grain-oriented electrical steel sheet Expired - Lifetime US3908432A (en)

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JP48031452A JPS49119817A (enrdf_load_stackoverflow) 1973-03-20 1973-03-20

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US (1) US3908432A (enrdf_load_stackoverflow)
JP (1) JPS49119817A (enrdf_load_stackoverflow)
BE (1) BE812533A (enrdf_load_stackoverflow)
FR (1) FR2222442B1 (enrdf_load_stackoverflow)
GB (1) GB1456445A (enrdf_load_stackoverflow)
IT (1) IT1009683B (enrdf_load_stackoverflow)
SE (1) SE409472B (enrdf_load_stackoverflow)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4204890A (en) * 1977-11-11 1980-05-27 Kawasaki Steel Corporation Method of producing non-oriented silicon steel sheets having an excellent electromagnetic property
US4280856A (en) * 1980-01-04 1981-07-28 Kawasaki Steel Corporation Method for producing grain-oriented silicon steel sheets having a very high magnetic induction and a low iron loss
EP0047129A1 (en) * 1980-08-27 1982-03-10 Kawasaki Steel Corporation Grain-oriented silicon steel sheets having a very low iron loss and methods for producing the same
US4421574A (en) * 1981-09-08 1983-12-20 Inland Steel Company Method for suppressing internal oxidation in steel with antimony addition
US4439252A (en) * 1981-09-26 1984-03-27 Kawasaki Steel Corporation Method of producing grain-oriented silicon steel sheets having excellent magnetic properties
US4592789A (en) * 1981-12-11 1986-06-03 Nippon Steel Corporation Process for producing a grain-oriented electromagnetic steel sheet or strip
US6280534B1 (en) * 1998-05-15 2001-08-28 Kawasaki Steel Corporation Grain oriented electromagnetic steel sheet and manufacturing thereof
US20120304721A1 (en) * 2010-11-26 2012-12-06 Baoshan Iron & Steel Co., Ltd. Cold-rolling method for preventing fracture of high-silicon strip steel

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61117215A (ja) * 1984-10-31 1986-06-04 Nippon Steel Corp 鉄損の少ない一方向性電磁鋼板の製造方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3345219A (en) * 1960-05-04 1967-10-03 Vacuumschmelze Ag Method for producing magnetic sheets of silicon-iron alloys
US3802936A (en) * 1969-04-14 1974-04-09 Kawasaki Steel Co Method of making grain oriented electrical steel sheet

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3632456A (en) * 1968-04-27 1972-01-04 Nippon Steel Corp Method for producing an electromagnetic steel sheet of a thin sheet thickness having a high-magnetic induction

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3345219A (en) * 1960-05-04 1967-10-03 Vacuumschmelze Ag Method for producing magnetic sheets of silicon-iron alloys
US3802936A (en) * 1969-04-14 1974-04-09 Kawasaki Steel Co Method of making grain oriented electrical steel sheet

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4204890A (en) * 1977-11-11 1980-05-27 Kawasaki Steel Corporation Method of producing non-oriented silicon steel sheets having an excellent electromagnetic property
US4280856A (en) * 1980-01-04 1981-07-28 Kawasaki Steel Corporation Method for producing grain-oriented silicon steel sheets having a very high magnetic induction and a low iron loss
EP0047129A1 (en) * 1980-08-27 1982-03-10 Kawasaki Steel Corporation Grain-oriented silicon steel sheets having a very low iron loss and methods for producing the same
US4421574A (en) * 1981-09-08 1983-12-20 Inland Steel Company Method for suppressing internal oxidation in steel with antimony addition
US4483723A (en) * 1981-09-08 1984-11-20 Inland Steel Company Steel with antimony addition
US4439252A (en) * 1981-09-26 1984-03-27 Kawasaki Steel Corporation Method of producing grain-oriented silicon steel sheets having excellent magnetic properties
US4592789A (en) * 1981-12-11 1986-06-03 Nippon Steel Corporation Process for producing a grain-oriented electromagnetic steel sheet or strip
US6280534B1 (en) * 1998-05-15 2001-08-28 Kawasaki Steel Corporation Grain oriented electromagnetic steel sheet and manufacturing thereof
US20120304721A1 (en) * 2010-11-26 2012-12-06 Baoshan Iron & Steel Co., Ltd. Cold-rolling method for preventing fracture of high-silicon strip steel
US9056343B2 (en) * 2010-11-26 2015-06-16 Baoshan Iron & Steel Co., Ltd. Cold-rolling method for preventing fracture of high-silicon strip steel

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GB1456445A (en) 1976-11-24
IT1009683B (it) 1976-12-20
JPS49119817A (enrdf_load_stackoverflow) 1974-11-15
BE812533A (fr) 1974-07-15
FR2222442B1 (enrdf_load_stackoverflow) 1978-07-28
FR2222442A1 (enrdf_load_stackoverflow) 1974-10-18
SE409472B (sv) 1979-08-20

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