US2867558A - Method for producing grain-oriented silicon steel - Google Patents

Method for producing grain-oriented silicon steel Download PDF

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Publication number
US2867558A
US2867558A US631542A US63154256A US2867558A US 2867558 A US2867558 A US 2867558A US 631542 A US631542 A US 631542A US 63154256 A US63154256 A US 63154256A US 2867558 A US2867558 A US 2867558A
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percent
sheet
cold
temperature
grain size
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US631542A
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John E May
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General Electric Co
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General Electric Co
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Priority to BE563546D priority Critical patent/BE563546A/xx
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Priority to FR1192468D priority patent/FR1192468A/fr
Priority to FR754769A priority patent/FR72689E/fr
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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
    • C21D8/1244—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
    • C21D8/1272—Final recrystallisation annealing

Definitions

  • the sheet materials to which my invention is related are usually referred to in the art as electrical silicon steel or, more properly, silicon-iron, composed primarily of iron alloyed with about 2.5 to 4.0 percent silicon and containing relatively minor amounts of impurities,
  • Such alloys crystallize in the body-centered cubic crystallographic system at room temperature. As is well known, this refers to the symmetrical distribution or arrangement which the atoms forming the individual crystals or grains assume in such materials. In these materials, the smallest prism possessing the full symmetry of the crystal is termed the unit cell and is cubic in form.
  • This unit cube is composed of nine atoms, eight arranged at the corners of the unit cube with the remaining atom positioned at the geometric center of the cube.
  • Each unit cell in a given grain or crystal in these materials is substantially identical in shape and orientation with every other unit cell comprising the grain.
  • the unit cells or body-centered unit cubes comprising these materials each have a high degree of magnetic anisotropy with respect to the crystallographic planes and directions of the unit cube and hence, each grain or crystal comprising a plurality of such unit cells ex-' hibits a similar anisotropy.
  • crystals of the silicon-iron alloys to which this invention is directed are known to have their direction of easiest magnetization parallel to the unit cube edges, their next easiest direction of magnetization perpendicular to a plane passed through diagonally opposite parallel unit cube edges and their least easiest direction of magnetization perpendicular to a plane passed through a pair of diagonally opposite atoms in a first unit cube face and a single atom in the unit cube face which is parallel to the first face.
  • these crystallographic planes and directions are conventionally identified in terms of Miller Indices, a more complete discussion of which may be found in Structure of Metals, C. S. Barrett, McGraw-I-Iill Book Company, New York, New York, 2nd edition, 1952, pp. l-25 and will be referred to as, respectively, the (100) plane and the [100] direction, the (110) plane and the [110] direction, and the (111) plane and the [111] direction.
  • the silicon-iron alloys may be fabricated by unidirectional rolling and heat treatment to form sheet or strip material composed of a plurality of crystals or grains, a majority of which have 2 their atoms arranged so that their crystallographic planes have a similar or substantially identical orientation to the plane of the sheet or strip and to a single direction in said plane.
  • This material is usually referred to as oriented or grain-oriented silicon-iron sheet or strip and is characterized by having 50 percent or more of its component grains oriented so that four of the cube edges of the unit cells of such grains are substantially parallel to the plane of the sheet or strip and to the direction in which it was rolled and a (110) crystallographic plane substantially to the plane of the sheet.
  • the so-oriented grains have a direction of easiest magnetization in the plane of the sheet in the rolling direction and the next easiest direction of magnetization in the plane of the sheet in a transverse to rolling direction.
  • This is conventionally referred to as a cube on edge orientation or the' (110) [001] texture.
  • it is desirable to have as high a degree of grain orientation as attainable, preferably more than 70 percent, in order that the magnetic properties in the plane of the sheet and in the rolling direction may approach the maximum attained in single crystals in the [100] direction.
  • a principal object of my invention is the provision of a method of fabrication of such silicon-iron alloys to insure that the highest attainable degree of grain orientation may be consistently produced in the final sheet or strip material.
  • Other and specifically difierent objects of my invention will become apparent to those skilled in the art from the following detailed disclosure.
  • Fig. 1 is a graphical representation of the effect of'temperature and impurity composition on intermediate grain size
  • Fig. 2 is a graphical representation of the relationship between impurity and intermediate grain size'under an exemplary given annealing treatment.
  • the grain size of these materials at an intermediatestage'of'fabrication has an important and controllingrelationship*upon the final -degreeof'textu're attainable; More particularly; these mate rials'areconventionally produced-by hot reducing ingots to sheet or strip' like' bodies, usually 'less than 0.150" in thickness, called band, usually by rolling operations. These materialsiare then subjected to cold reduction by rolling'with appropriate intermediate heat treatmentto finalthickness, for example, about 0.01 to 0.015" thickness. This cold rolled material is then conventionally given a" decarburizing heat'treatment and a texture developing anneal.
  • the cold rolling schedule employed is usually one in which the cold reduction is accomplished in'at'least two steps, separated by an annealing treatment. It is essential, as pointed out in my copending application, to control the grain size of the annealed strip before cold reducing the strip to final thickness. This grain size is referred to as the intermediate grain size, and should be maintained between an average measured grain size of about0.010 and.0.030 mm.
  • the amount of cold reduction necessary to produce this critical intermediate grain size is at least 40 percent in thickness during the penultimate cold rolling sequence and that a cold reduction of at least percent is necessary in the ultimate or final cold rolling sequence in order to develop the desired degree of orientation.
  • the material develops an equiaxed relatively uniform fine grain structure, usuallyreferred to as the primary recrystallization structure.
  • These grains have essentially a random orientation, in other words, a relatively few have the desired texture while the majority have other, specifically difierent oriencations.
  • .Asthe heat treatment continues,'tl1ese primary grains tend to grow somewhat, however, grains having the (110) [001] orientation grow at a much greater rate than'the primary matrix grains and consume their less favorably oriented neighboring grains.
  • These secondary' grains are easily identifiable since they become during their development, up to millions of times as large as the primary grains. It has been found that unless the secondary recrystallization phenomenon occurs during this heat treatment, well developed or strong (110) [001] textures are not developed.
  • alloys listed in the foregoing table were melted and cast as 6 pound ingots by melting the iron under vacuum, deoxidizing the melt with hydrogen for 30 minutes, adding the silicon and selected impurities, permitting the melt to solidify, pumping the hydrogenout, recreating a vacuum, andremeltingand casting thealloys under the vacuum. All the compositions listed in Table I are the result of chemical analyses performed upon the ingots.
  • the ingots resulting from casting these alloys were forged and drawn-at temperatures between 800 C. and 1000 C. to 2" x 1," cross-section bars. These bars were then hot-rolled to from O.2" to 0.4" in thickness and then cold-rolled to about 0.100" thick and annealed to obtain a characteristic equi-axed grain structure; These anealed bands were cold reduced from 0.100 to 0.028" intermediate thickness and separate portions were annealed at different temperatures for 15 minutes eachin a protective atmosphere. The grain size of each of the portions was determined, the grain size versus temperature plotted in Fig. 1, and the portionswerecold rolled to 0.014" thickness strip. Portions of each so-reduced strip were annealed in a protective atmosphere at diffen ent temperatures for 1 hour each and the primary grain size of each was measured and is reproduced in Table II.
  • GROUP III INTERMEDIATE ANNEAL AI 1,000 o.
  • each cold reduced strip was annealed in a temperature gradient furnace.
  • these strips were arranged in an annealing furnace-so thatthe temperature at one end of each strip was maintainedat 850 C. and the temperature gradually increasedalong the length of each'strip to 1145 C. at the other end of each strip.
  • these strips After these strips have beenannealed for a sufiicient' time to insurecomplete recrystallization, they were removed, etched, and subjected to macroscopic grain structure examination.
  • a temperature range for annealing alloys .5. l and 2 which contain 0.005 percent and no sulfur respectively, in order to produce intermediate grain sizes between 0.01 and 0.030 mm. is very narrow.
  • this critical range of grain size is obtainable over much wider temperature ranges.
  • alloy 7 with a sulfur content of 0.046 percent and a manganese content of 0.110 percent may be annealed under these conditions at temperatures as high as about 975 C. without causing excessive grain growth.
  • alloys 1 and 2 are incapable of developing any appreciable degree of the desired structure.
  • an alloy having a nominal 3.3 percent silicon content, 0.09 percent titanium, and 0.032 percent sulfur, balance substantially all electrolytic iron to which no manganese was added, and a substantially identical alloy containing 0.13 percent chromium instead of the titanium, and 0.033 percent sulfur, were prepared by the procedure disclosed for alloys 1-7. It was found that these alloys exhibited secondary recrystallization up to a final annealing temperature of about 1175 C. for the titanium alloy, and up to a final annealing temperature of about 1075 C. for the chromium alloy, providing the intermediate annealing temperature did not exceed 1000 C. and the intermediate grain size lay between about 0.010 and 0.030 mm.
  • Fig. 2 is plotted the effect of impurity concentration, expressed as percent sulfur, upon the intermediate grain size obtained by means of a 900 C. anneal for 15 minutes.
  • the alloys contain a sufficient amount of another material such as manganese, titanium, or chromium, for example, to combine with sulfur to form their respective sulfides. It will be seen that such alloys should contain at least about 0.015 percent sulfur in order that an intermediate grain size between 0.010 and 0.030 mm. may be readily achieved and which develop secondary recrystallized grain structure during the final annealing treatment.
  • the method of fabricating polycrystalline sheet-like bodies of metal comprising electrical grade silicon-iron alloy consisting essentially of from about 2.5 to 4.0 percent silicon, more than about 0.012 percent sulfur, a sutncient amount of an element selected from the group consisting of manganese, titanium and chromium to combine with the sulfur to form sulfide and the balance substantially all iron comprising the steps of cold reducing an at least partially recrystallized body of said alloy at least 40 percent to form a body of intermediate thickness, heat treating said cold reduced body at a temperature of between 700 C. to 1000 C. to produce a measured average grain size of from about 0.010 mm.

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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)
US631542A 1956-12-31 1956-12-31 Method for producing grain-oriented silicon steel Expired - Lifetime US2867558A (en)

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Application Number Priority Date Filing Date Title
BE563546D BE563546A (enrdf_load_html_response) 1956-12-31
US631542A US2867558A (en) 1956-12-31 1956-12-31 Method for producing grain-oriented silicon steel
FR1192468D FR1192468A (fr) 1956-12-31 1957-12-26 Alliages ferreux magnétiques, à cristallites orientés
FR754769A FR72689E (fr) 1956-12-31 1957-12-27 Alliages ferreux magnétiques à cristallites orientés

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Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2939810A (en) * 1956-12-31 1960-06-07 Gen Electric Method for heat treating cube-on-edge silicon steel
US3042556A (en) * 1960-02-02 1962-07-03 Gen Electric Process for treating steel
US3069299A (en) * 1956-12-31 1962-12-18 Gen Electric Process for producing magnetic material
US3090711A (en) * 1959-07-06 1963-05-21 Armco Steel Corp Procedure for secondary recrystallization
US3124491A (en) * 1960-05-23 1964-03-10 Heavy gauge double oriented magnetic sheet material
US3130092A (en) * 1959-05-29 1964-04-21 Armco Steel Corp Process of making cubic texture silicon-iron
US3147158A (en) * 1961-11-22 1964-09-01 Gen Electric Process for producing cube-on-edge oriented silicon iron
US3152929A (en) * 1959-08-17 1964-10-13 Westinghouse Electric Corp Process for producing silicon steel with preferred orientation
US3157538A (en) * 1960-05-17 1964-11-17 Kawasaki Steel Co Grain oriented silicon steel containing selenium and method of making the same
US3239332A (en) * 1962-03-09 1966-03-08 Fuji Iron & Steel Co Ltd Electric alloy steel containing vanadium and copper
US3278348A (en) * 1965-01-28 1966-10-11 Westinghouse Electric Corp Process for producing doubly oriented cube-on-face magnetic sheet material
US3333992A (en) * 1964-06-29 1967-08-01 Armco Steel Corp Production of oriented silicon-iron using grain growth inhibitor during primary recrystallization heat treatment
US3333993A (en) * 1965-04-02 1967-08-01 Armco Steel Corp Production of thin, oriented siliconiron wherein grain growth inhibitor is added to primary recrystallization heat treatment atmosphere as function of mn content and final thickness
US3855019A (en) * 1973-05-07 1974-12-17 Allegheny Ludlum Ind Inc Processing for high permeability silicon steel comprising copper
US3855018A (en) * 1972-09-28 1974-12-17 Allegheny Ludlum Ind Inc Method for producing grain oriented silicon steel comprising copper
US4202711A (en) * 1978-10-18 1980-05-13 Armco, Incl. Process for producing oriented silicon iron from strand cast slabs
US4306922A (en) * 1979-09-07 1981-12-22 British Steel Corporation Electro magnetic steels
US4478653A (en) * 1983-03-10 1984-10-23 Armco Inc. Process for producing grain-oriented silicon steel
US7736444B1 (en) 2006-04-19 2010-06-15 Silicon Steel Technology, Inc. Method and system for manufacturing electrical silicon steel
US9997283B2 (en) * 2010-12-23 2018-06-12 Posco Grain-oriented electric steel sheet having superior magnetic property

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2158065A (en) * 1935-01-09 1939-05-16 American Rolling Mill Co Art of producing magnetic materials

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2158065A (en) * 1935-01-09 1939-05-16 American Rolling Mill Co Art of producing magnetic materials

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3069299A (en) * 1956-12-31 1962-12-18 Gen Electric Process for producing magnetic material
US2939810A (en) * 1956-12-31 1960-06-07 Gen Electric Method for heat treating cube-on-edge silicon steel
US3130092A (en) * 1959-05-29 1964-04-21 Armco Steel Corp Process of making cubic texture silicon-iron
US3090711A (en) * 1959-07-06 1963-05-21 Armco Steel Corp Procedure for secondary recrystallization
US3152929A (en) * 1959-08-17 1964-10-13 Westinghouse Electric Corp Process for producing silicon steel with preferred orientation
US3042556A (en) * 1960-02-02 1962-07-03 Gen Electric Process for treating steel
US3157538A (en) * 1960-05-17 1964-11-17 Kawasaki Steel Co Grain oriented silicon steel containing selenium and method of making the same
US3124491A (en) * 1960-05-23 1964-03-10 Heavy gauge double oriented magnetic sheet material
US3147158A (en) * 1961-11-22 1964-09-01 Gen Electric Process for producing cube-on-edge oriented silicon iron
US3239332A (en) * 1962-03-09 1966-03-08 Fuji Iron & Steel Co Ltd Electric alloy steel containing vanadium and copper
US3333992A (en) * 1964-06-29 1967-08-01 Armco Steel Corp Production of oriented silicon-iron using grain growth inhibitor during primary recrystallization heat treatment
US3278348A (en) * 1965-01-28 1966-10-11 Westinghouse Electric Corp Process for producing doubly oriented cube-on-face magnetic sheet material
US3333993A (en) * 1965-04-02 1967-08-01 Armco Steel Corp Production of thin, oriented siliconiron wherein grain growth inhibitor is added to primary recrystallization heat treatment atmosphere as function of mn content and final thickness
US3855018A (en) * 1972-09-28 1974-12-17 Allegheny Ludlum Ind Inc Method for producing grain oriented silicon steel comprising copper
US3855019A (en) * 1973-05-07 1974-12-17 Allegheny Ludlum Ind Inc Processing for high permeability silicon steel comprising copper
US4202711A (en) * 1978-10-18 1980-05-13 Armco, Incl. Process for producing oriented silicon iron from strand cast slabs
US4306922A (en) * 1979-09-07 1981-12-22 British Steel Corporation Electro magnetic steels
US4478653A (en) * 1983-03-10 1984-10-23 Armco Inc. Process for producing grain-oriented silicon steel
EP0124964A1 (en) * 1983-03-10 1984-11-14 Armco Advanced Materials Corporation Process for producing grain-oriented silicon steel
US7736444B1 (en) 2006-04-19 2010-06-15 Silicon Steel Technology, Inc. Method and system for manufacturing electrical silicon steel
US9997283B2 (en) * 2010-12-23 2018-06-12 Posco Grain-oriented electric steel sheet having superior magnetic property

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FR1192468A (fr) 1959-10-27

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