Classifications

• • 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
  • C21D8/1244—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest
  • C21D8/1266—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest between cold rolling steps
• • 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
  • C21D8/1244—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest
  • C21D8/1261—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest following hot rolling

Definitions

• Dropkin 5 7 ABSTRACT A process for producing silicon steel having a cubeon-edge orientation and a permeability of at least 1850 (G/O,,) at 10 oersteds, which includes the steps of: cold rolling silicon steel; annealing the cold rolled steel prior to a final cold roll, at a temperature of from 1400 to 1700F for a period of from 15 seconds to 2 hours; cooling the annealed steel at a rate substantially equivalent to a still air cool; and cold rolling the cooled steel at a reduction of at least 80 percent.
• the present invention relates to a process for producing electromagnetic silicon steel having a cube-on-edge orientation and a permeability of at least 1850 (G/O at 10 oersteds.
• Oriented silicon steels containing 2.60 to 4.0 percent silicon are generally produced by processes which involve hot rolling, a double cold reduction, an anneal before each cold roll and a high temperature texture anneal. Characterizing these steels are permeabilities at 10 oersteds of from 1790 to 1840 (6/0). In recent years a number of patents have disclosed silicon steels with permeabilities in excess of 1850 (6/0,) at 10 oersteds. Of these, US. Pat. Nos. 3,287,183, 3,632,456 and 3,636,579 appear to be the most interesting from a processing standpoint. US. Pat. No. 3,287,183 which issued on Nov.
• 3,632,456 anneals a hot rolled band at a temperature of from 1382 to 2192F depending upon its silicon content, rapidly cools the annealed band and then proceeds to subject it to at least two cold rollings.
• Described herein is another, and improved method for producing silicon steel having a cube-on-edge orientation and a permeability of at least 1850 (6/0 at 10 oersteds from steel of a particular chemistry.
• the method includes the steps of: cold rolling silicon steel; annealing the cold rolled steel prior to a final cold roll, at a temperature of from 1400 to 1700F for a periiod of from seconds to 2 hours; cooling the annealed steel at a rate substantially equivalent to a still air cool; and cold rolling the cooled steel at a reduction of at least 80 percent. It differs and is contradictory to the methods of heretofore referred to U.S. Pat. Nos.
• the present invention provides a method for producing silicon steel having a cube-on-edge orientation and a permeability of at least 1850 (G/O and preferably at least 1900 (G/O at 10 oersteds.
• Involved therein are the steps of: preparing a melt of silicon steel having, by weight, up to 0.07% carbon, from 2.60 to 4.0% silicon, from 0.03 to 0.24% manganese, from 0.01 to 0.07% sulfur, from 0.015 to 0.04% aluminum, up to 0.02% nitrogen, and from 0.1 to 0.5% copper; casting the steel; hot rolling the steel into a hot rolled band, cold rolling the hot rolled band with or without an intermediate anneal between the hot rolling and the cold rolling, the intermediate anneal being at a maximum temperature of 1700F; subjecting the steel to at least one additional cold rolling; subjecting the steel to a final annealing prior to the final cold rolling; decarburizing the steel; and final texture annealing the steel.
• Preferred conditions include annealing at a temperature of from 1450 to 1650F and cold rolling at a reduction of at least percent.
• still air cools include those wherein the steel is cooled in a static atmosphere as well as those wherein there is relative motion between the atmosphere and the steel, as in a continuous processing line, so long as there is no deliverate intention to cause the motion for cooling purposes.
• Annealing at a temperature of from l400 to 1700F for the final anneal prior to the final cold roll is, however, believed to be particularly beneficial in that it conditions the steel for cold rolling, provides an operation during which inhibitors can form, and most importantly, increases the uniformity in which the inhibitors are distributed as essentially only ferrite phase is present in the steel at temperatures below 1700F, contrasted to the presence of austenite and ferrite phases and different solubilities for the inhibiting elements in each phase at somewhat higher temperatures.
• the invention primarily pertains to aluminum nitride, and manganese sulfide and/or manganese copper sulfide, which are discussed in greater detail hereinbelow.
• Illustrative atmospheres therefore include nitrogen; reducing gases such as hydrogen; inert gases such as argon; air; and mixtures thereof.
• nitrogen nitrogen
• reducing gases such as hydrogen
• inert gases such as argon
• air air
• mixtures thereof for similar reasons, as with the final anneal prior to the final cold roll the hot rolled band should not be annealed at temperatures in excess of 1700F; and when a hot rolled band anneal is desired it is preferred to carry it out at a temperature of from 1400 to 1700F.
• the annealed hot rolled band is generally cooled at a rate substantially equivalent to a still air cool.
• the cold rolling it should be pointed out that several roll passes can constitute a single cold rolling operation, and that plural cold rolling operations exist only when cold rolling passes are separated by. an anneal.
• the steel melt must include a silicon, aluminum, manganese, sulfur and copper. Silicon is necessary as it increases the steels resistivity, decreases it magnetostriction, decreases its magnetocrystalline anisotropy and hence decreases its core loss. Aluminum, manganese and sulfur are necessary as they form inhibitors which are essential to controlling the steels orientation and its properties which are dependent thereon.
• aluminum combines with nitrogen, in the steel or from the atmosphere, to form aluminum nitride
• manganese combines with sulfur to form manganese sulfide and/or manganese copper sulfide; and these compounds act so as to inhibit normal grain growth during the final texture anneal, while at the same time, aiding in the development of secondary recrystallized grains having the desired cube-on-edge orientation.
• Copper in addition to possibly forming manganese copper sulfide, is believed to be beneficial in that it is hypothesized that copper can lower the annealing temperature, improve rollability, simplify melting and relax annealing atmosphere requirements.
• a steel in which the process of the present invention is particularly adaptable to consists essentially of, by weight, from 0.02 to 0.07% carbon, from 2.60 to 3.5% silicon, a manganese equivalent of from 0.05 to 0.24% as expressed by an equivalency equation of %Mn (0.1 to 0.25) X %Cu, from 0.01 to 0.05% sulfur, from 0.015 to 0.04% aluminum, from 0.0030 to 0.0090% ni trogen, from 0.1 to 0.3% copper, balance iron and residuals; and wherein the ratio of manganese equivalent to sulfur'is in the range of from 2.0 to 4.75.
• the steel has its chemistry balanced so as to produce a highly beneficial structure when processed according to the present invention.
• Samples 1 of silicon steel were cast and processed into silicon steel having a cube-onedge orientation from 5 different heats of BOF silicon steel.
• the chemistry of the samples appears hereinbelow in Table l.
• a process for producing electromagnetic silicon steel having a cube-on-edge, orientation and a permeability of at least 1850 6/0 at 10 oersteds which process includes the steps of: preparing a melt of silicon steel consisting essentially of, by weight, up to 0.07% carbon, from 2.60 to 4.0% silicon, from 0.03 to 0.24% manganese, from 0.01 to 0.07% sulfur, from 0.015 to 0.04% aluminum, up to 0.02% nitrogen, from 0.1 to 0.5% copper and the balance iron; casting said steel; hot rolling said steel into a hot rolled band; cold rolling said hot rolled band with or without an intermediate anneal between said hot rolling and said cold rolling, said intermediate anneal being at a maximum temperature of 1700F; subjecting said band to at least one ad- Processing for the five samples involved soaking at an elevated temperature for several hours, blooming, hot
• said steel consists essentially of, by weight, from 0.02 to 0.07% carbon, from 2.60 to 3.5% silicon, a manganese equivalent of from 0.05 to 0.24%, as expressed by an equivalency equation of %Mn (0.1 to 0.25) X %CU, from 0.01 to 0.05% sulfur, from 0.015 to 0.04% aluminum, from 0.0030 to 0.0090% nitrogen, from 0.1 to 0.3% copper, balance iron and residuals; and wherein the ratio of manganese equivalent to sulfur is in the range of from 2.0 to 4.75.
• hot rolled band is cold rolled without an intermediate anneal between hot rolling and cold rolling.

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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)
• Metal Rolling (AREA)

Priority Applications (13)

Applications Claiming Priority (1)

Publications (1)

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Cited By (10)

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Citations (5)

• 1973
  • 1973-05-07 US US00358238A patent/US3855021A/en not_active Expired - Lifetime
• 1974
  • 1974-04-18 CA CA198,058A patent/CA1010761A/en not_active Expired
  • 1974-05-03 IT IT50772/74A patent/IT1011368B/it active
  • 1974-05-06 GB GB1980574A patent/GB1422766A/en not_active Expired
  • 1974-05-06 ES ES426018A patent/ES426018A1/es not_active Expired
  • 1974-05-07 JP JP49049841A patent/JPS6025495B2/ja not_active Expired
  • 1974-05-07 DE DE19742422074 patent/DE2422074B2/de not_active Ceased

Patent Citations (5)

Non-Patent Citations (2)

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