US3923560A - Low-carbon steel sheets temper-rolled after the final anneal to improve magnetic properties - Google Patents

Low-carbon steel sheets temper-rolled after the final anneal to improve magnetic properties Download PDF

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Publication number
US3923560A
US3923560A US372432*[A US37243275A US3923560A US 3923560 A US3923560 A US 3923560A US 37243275 A US37243275 A US 37243275A US 3923560 A US3923560 A US 3923560A
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steel
percent
kilogauss
permeability
exhibit
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US372432*[A
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Lester J Regitz
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United States Steel Corp
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United States 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
    • C21D8/1233—Cold rolling
    • 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

  • silicon sheet steels are widely used in the production of magnetic core components in electrical equipment such as motors, generators, transformers, and the like. These favorable magnetic properties, namely high magnetic permeability, high electrical resistance and low hysteresis losses, will minimize wasteful conversion of electrical energy into heat, and will therefore permit manufacture of electrical equipment having greater power and efficiency.
  • the silicon sheet steels In order to effect and optimize the desired magnetic properties, however, the silicon sheet steels must be produced under carefully controlled and exacting processing parameters. Silicon sheet steels are therefore substantially more expensive than other more conventional fiat rolled steel products.
  • low-carbon sheet steels for magnetic applications are produced from conventional low-carbon steel heats having less than 0.1 percent carbon and the usual residual elements at normal levels for coldrolled products.
  • the rolling procedures are similar to those used for other cold-rolled products. Specifically, the production steps are usually limited to hot rolling a low-carbon ingot to slab form; hot rolling the slab to sheet form; pickling the hot rolled sheet, cold rolling the pickled sheet for areduction of 40 to 80 percent;
  • temper rolling elongations are minimized at A to 2 percent.
  • the commercially produced low-carbon sheet steels for magnetic applications when rolled to 18.5 mils thickness, typically exhibit permeabilities in the rolled direction of from 5000 to 6000 at l0 kilogauss, with core losses of from 1.3 to 1.6 watts/lb.
  • permeabilities in the rolled direction typically range from 2000 to 4000 with core losses of 3.0 to 4.0 watts/lb.
  • Sheets rolled to 25 mils typically exhibit permeabilities in the rolled direction of from 4200 to 4800, with core losses of 1.8 to 2.0 watts/lb. at 10 kilogauss; and permeabilities in the rolled direction of from 2000 to 3000 with core losses of 4.2 to 4.8 watts/lb. at 15 kilogauss.
  • FIGS. 1 through 4 are graphs showing test results of one experimental heat described :at the end of this specification. The graphs show permeabilities and core losses at 10 and I5 kilogauss as a function of percent temperrolling elongation.
  • the starting steel- should have a composition substantially the same as those low-carbon sheet steels presently produced commercially.
  • the composition of the steel is usually as follows: 0.02 to 0.10 percent carbon; 0.40-0.60 percent max. manganese; 0.02-0.09 percent max. phosphorus; 0.025 percent max. sulfur;
  • a steel heat having the above composition, is cast into ingot form and then hot rolled to slab form in accordance with conventional slabbing mill practices, or continuously cast into slab form in accordance with conventional continuous casting practice.
  • the slab is then reheated and hot rolled to sheet having a thickness of about 0.06 inch or between 0.05 and 0.100 inch, such that the finishing temperature upon exit from the finishing roll train is within the range l430 to 1620F.
  • the sheet is thereafter cooled with water sprays so that it is coiled at a temperature of from 900 to 1200F.
  • the preferred hot rolling practice is to attain a temperature within the range 1900 to 1950F when the steel is about 1 inch thick, and 1460 to 1600F when the steel is finished.
  • the steel is suitably pickled to remove mill scale and then cold rolled to effect a thickness reduction of from 40 to 80 percent. Thereafter, the sheet is suitably annealed to effect recrystallization.
  • the annealing is preferably performed in a box annealing furnace at a temperature of from 1 125 to 1300F for 3 to 30 hours.
  • the annealing of the cold rolled sheet steel completes the process and the steel is sold thereafter.
  • the most common commercial practice has been to temper roll the annealed sheet effecting plastic elongations no greater than 2 percent for the purpose of improving the sheets flatness and thus enhance its slitting and punching characteristics and render it more suitable for laminated end products. Elongations in excess of 2 percent are avoided because such elongations will usually result in distortions of sheet flatness and variations in gage, or thickness, across the sheet width.
  • the crux of this invention resides in the unexpected discovery that sheet steel produced in accordance with the above process can be provided with very substantially improved magnetic properties if the final temper roll is sufficient to provide a plastic elongation within the critial range of from 6 to percent, and preferably between 7 and 9 percent.
  • the prior art low-carbon sheet steel rolled to a thickness of 18.5 mils and tested at 10 kilogauss typically exhibit permeabilities of 5000 to 6000, with core losses of from 1.3 to 1.6 watts/lb.
  • sheet steels produced in accordance with this invention will exhibit optimum permeabilities of about 7200 and core losses of about 1.1 watts/lb.
  • Table 1 below contrasts the optimum magnetic properties achieved by the practice of this invention with the magnetic properties obtainable in prior
  • Table 1 below contrasts the optimum magnetic properties achieved by the practice of this invention with the magnetic properties obtainable in prior
  • This heat was cast into ingot form and hot-rolled first to slab form and then to 0.060 inch thick sheet. Hot rolling was controlled such that the sheet was at a temperature of 1950F at 1 inch thickness. and exited the final rolls at 1440F. Prior to coiling, the hot rolled sheet was cooled to l 180F with water sprays.
  • the hot rolled sheet was then segmented into five portions, and cold rolled to various gages, such that the final or temper rolling following annealing, various degrees of deformation could be imposed in reducing the sheets to one of two final thicknesses.
  • the intermediate thicknesses, final thicknesses and degree of temper rolling are shown in Table 11 below.
  • the sheets were then temper rolled as indicated in the above table and sheared into test strips.
  • the longitudinal test strips were annealed for one hour at 1450 in the above atmosphere to relieve shearing strains, and the magnetic properties thereafter measured at 60 Hertz.
  • the resulting properties are tabulated in the above table and shown graphically in FIG 1-4, which are plots of permeability and core losses as a function of percent plastic elongation at 10 and 15 kilogauss. The superior effect of temper rolling between 6 and 10 percent elongation is clearly demonstrated.
  • a process for producing low-carbon sheet steel for magnetic applications consisting of; forming a steel slab consisting of 0.02 to 0.10 percent carbon, 0.40 to 0.60 percent manganese, 0.02 to 0.09 percent phosphorus, 0.025 maximum percent sulfur, 0.010 maximum percent silicon and the balance iron and residual impurities; hot rolling said slab to a thickness of 0.050 to 0.100 inch with a finishing temperature within the range 1430 to 1620F; coiling the hot rolled steel at a temperature of 900 to 1200F; cooling the coiled steel to ambient temperature; cleaning the steel to remove mill scale; cold rolling the cleaned steel to effect a thickness reduction of 40 to 80 percent; annealing the cold rolled steel at a temperature of 1 125 to 1300F to effect recrystallization thereof; and finally temper rolling the annealed steel sufficient to effect a plastic elongation of 6 to 10 percent to improve the steels magnetic properties such that at 18.5 mils the steel will exhibit a permeability in excess of 6000 with core losses of less than 1.3 watts
  • a low-carbon sheet steel for magnetic applications produced by the'process consisting of hot rolling a steel slab consisting of 0.02 to 0.10 percent carbon, 0.40 to 0.60 percent manganese, 0.02 to 0.09 percent phosphorus, 0.025 maximum percent sulfur, 0.010 maximum percent silicon and the balance iron and residual impurities to a thickness of 0.050 to 0.100 inch with a finishing temperature within the range 1430 to 1620F, coiling the hot rolled steel at a temperature of 900-1200F, cooling the coil, cleaning the coil to remove mill scale, cold rolling the cleaned hot rolled steel to effect a thickness reduction of 40 to percent, annealing the cold.

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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)
  • Soft Magnetic Materials (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
US372432*[A 1971-04-23 1975-12-02 Low-carbon steel sheets temper-rolled after the final anneal to improve magnetic properties Expired - Lifetime US3923560A (en)

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US13680571A 1971-04-23 1971-04-23

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US (1) US3923560A (xx)
JP (1) JPS558567B1 (xx)
BE (1) BE782069A (xx)
BR (1) BR7202339D0 (xx)
CA (1) CA954020A (xx)
CS (1) CS197209B2 (xx)
DE (1) DE2219059A1 (xx)
FR (1) FR2133742B1 (xx)
GB (1) GB1393175A (xx)
IT (1) IT954752B (xx)
NL (1) NL7205206A (xx)
PL (1) PL71048B1 (xx)
RO (1) RO56972A (xx)
SU (1) SU623527A3 (xx)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0002929A1 (en) * 1977-12-22 1979-07-11 Uss Engineers And Consultants, Inc. Use of plain low carbon steels for electrical applications
US4309228A (en) * 1980-03-24 1982-01-05 British Steel Corporation Electro magnetic steels
US5769974A (en) * 1997-02-03 1998-06-23 Crs Holdings, Inc. Process for improving magnetic performance in a free-machining ferritic stainless steel
USRE35967E (en) * 1994-04-26 1998-11-24 Ltv Steel Company, Inc. Process of making electrical steels
US6068708A (en) * 1998-03-10 2000-05-30 Ltv Steel Company, Inc. Process of making electrical steels having good cleanliness and magnetic properties
US6217673B1 (en) 1994-04-26 2001-04-17 Ltv Steel Company, Inc. Process of making electrical steels
US10808293B2 (en) 2015-07-15 2020-10-20 Ak Steel Properties, Inc. High formability dual phase steel

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4828001A (xx) * 1971-08-15 1973-04-13
US4548655A (en) * 1982-07-19 1985-10-22 Allegheny Ludlum Steel Corporation Method for producing cube-on-edge oriented silicon steel
JPS60175287U (ja) * 1984-04-26 1985-11-20 オ−・エスプロジエクト株式会社 自動麻雀卓
JPS60175288U (ja) * 1984-09-06 1985-11-20 オ−・エスプロジエクト株式会社 自動麻雀卓
JPS6362194U (xx) * 1986-10-09 1988-04-25
DE69025417T3 (de) * 1989-04-04 2000-03-30 Nippon Steel Corp Verfahren zum Herstellen von kornorientierten Elektrostahlblechen mit hervorragenden magnetischen Eigenschaften

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2242234A (en) * 1936-01-22 1941-05-20 American Rolling Mill Co Producing silicon steel sheets or strips
US2606848A (en) * 1949-10-19 1952-08-12 Republic Steel Corp Method of making sheet steel
US3180767A (en) * 1962-10-08 1965-04-27 Armco Steel Corp Process for making a decarburized low carbon, low alloy ferrous material for magnetic uses
US3188250A (en) * 1963-02-26 1965-06-08 United States Steel Corp Use of a particular coiling temperature in the production of electrical steel sheet
US3347718A (en) * 1964-01-20 1967-10-17 Armco Steel Corp Method for improving the magnetic properties of ferrous sheets
US3537918A (en) * 1968-04-25 1970-11-03 Westinghouse Electric Corp Method for producing cube-on-face oriented structure in a plain carbon iron
US3819426A (en) * 1972-07-31 1974-06-25 Nat Steel Corp Process for producing non-silicon bearing electrical steel

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1382885A (fr) * 1963-02-26 1964-12-18 United States Steel Corp Procédé de production d'une tôle d'acier pour la construction électrique

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2242234A (en) * 1936-01-22 1941-05-20 American Rolling Mill Co Producing silicon steel sheets or strips
US2606848A (en) * 1949-10-19 1952-08-12 Republic Steel Corp Method of making sheet steel
US3180767A (en) * 1962-10-08 1965-04-27 Armco Steel Corp Process for making a decarburized low carbon, low alloy ferrous material for magnetic uses
US3188250A (en) * 1963-02-26 1965-06-08 United States Steel Corp Use of a particular coiling temperature in the production of electrical steel sheet
US3347718A (en) * 1964-01-20 1967-10-17 Armco Steel Corp Method for improving the magnetic properties of ferrous sheets
US3537918A (en) * 1968-04-25 1970-11-03 Westinghouse Electric Corp Method for producing cube-on-face oriented structure in a plain carbon iron
US3819426A (en) * 1972-07-31 1974-06-25 Nat Steel Corp Process for producing non-silicon bearing electrical steel

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0002929A1 (en) * 1977-12-22 1979-07-11 Uss Engineers And Consultants, Inc. Use of plain low carbon steels for electrical applications
US4309228A (en) * 1980-03-24 1982-01-05 British Steel Corporation Electro magnetic steels
USRE35967E (en) * 1994-04-26 1998-11-24 Ltv Steel Company, Inc. Process of making electrical steels
US6217673B1 (en) 1994-04-26 2001-04-17 Ltv Steel Company, Inc. Process of making electrical steels
US5769974A (en) * 1997-02-03 1998-06-23 Crs Holdings, Inc. Process for improving magnetic performance in a free-machining ferritic stainless steel
US6068708A (en) * 1998-03-10 2000-05-30 Ltv Steel Company, Inc. Process of making electrical steels having good cleanliness and magnetic properties
US10808293B2 (en) 2015-07-15 2020-10-20 Ak Steel Properties, Inc. High formability dual phase steel

Also Published As

Publication number Publication date
PL71048B1 (xx) 1976-07-31
FR2133742B1 (xx) 1976-06-11
BR7202339D0 (pt) 1973-05-03
JPS558567B1 (xx) 1980-03-05
CS197209B2 (en) 1980-04-30
BE782069A (fr) 1972-10-13
GB1393175A (en) 1975-05-07
IT954752B (it) 1973-09-15
FR2133742A1 (xx) 1972-12-01
DE2219059A1 (de) 1972-11-02
NL7205206A (xx) 1972-10-25
CA954020A (en) 1974-09-03
RO56972A (xx) 1974-09-01
SU623527A3 (ru) 1978-09-05

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