EP0378131B1 - Procédé de fabrication d'une bande en acier électrique à grain orienté - Google Patents

Procédé de fabrication d'une bande en acier électrique à grain orienté Download PDF

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Publication number
EP0378131B1
EP0378131B1 EP90100231A EP90100231A EP0378131B1 EP 0378131 B1 EP0378131 B1 EP 0378131B1 EP 90100231 A EP90100231 A EP 90100231A EP 90100231 A EP90100231 A EP 90100231A EP 0378131 B1 EP0378131 B1 EP 0378131B1
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Prior art keywords
grain
annealing
decarburization
strip
diameter
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EP90100231A
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German (de)
English (en)
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EP0378131A3 (fr
EP0378131A2 (fr
Inventor
Nobuyuki C/O R & D Laboratories-Iii Takahashi
Yasunari C/O R & D Laboratories-Iii Yoshitomi
Tadashi C/O R & D Laboratories-Iii Nakayama
Yoshiyuki C/O R & D Laboratories-Iii Ushigami
Yozo C/O R & D Laboratories-Iii Suga
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Nippon Steel Corp
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Nippon Steel Corp
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Priority claimed from JP1001778A external-priority patent/JPH0832929B2/ja
Priority claimed from JP1086502A external-priority patent/JPH0684524B2/ja
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Publication of EP0378131A2 publication Critical patent/EP0378131A2/fr
Publication of EP0378131A3 publication Critical patent/EP0378131A3/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
    • C21D3/00—Diffusion processes for extraction of non-metals; Furnaces therefor
    • C21D3/02—Extraction of non-metals
    • C21D3/04—Decarburising
    • 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
    • C21D11/00—Process control or regulation for heat treatments
    • 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
    • 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
    • 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
    • C21D8/1272—Final recrystallisation annealing

Definitions

  • the present invention relates to a method of manufacturing a grain-oriented electrical steel strip adapted to be used as an iron core in a power supply transformer and a large size rotary machine.
  • the present invention relates to a method of manufacturing a grain-oriented electrical steel strip having an extremely high magnetic flux density by controlling the average value of grain sizes and the deviation cf primary recrystallization grain to desired values in a grain-oriented electrical steel strip manufacturing process as defined in claim 1.
  • a grain-oriented electrical steel strip is used as an iron core in a power supply transformer or a large size rotary machine, and is required to have excellent magnetic properties such as excitation property or a core loss property.
  • the magnetic property is generally exhibited by a magnetic flux density (B 8 value) at a magnetic field intensity of 800 A/m.
  • the core loss property is exhibited in general by a power loss W 17/50 (W/kg) per Kg of an iron core which is magnetized up to 1.7 tesla at a frequency of 50 Hz.
  • the magnetic flux density of the grain-oriented electrical steel strip is a very important property, that is, the higher the magnetic flux density the more satisfactory the core loss property becomes (the core loss value is decreased).
  • a grain-oriented electrical steel strip having a high magnetic flux density has in general a large grain size of secondary recrystallization grain so that the core loss thereof would be possibly unsatisfactory.
  • the core loss value of such a grain-oriented electrical steel strip can be decreased remarkable by a magnetic domain control technology disclosed in, for example, U.S. Patent No. 4,770,720.
  • a grain-oriented electrical steel strip has a magnetic easy axis of ⁇ 001> orientation in its rolling direction, and also has a ⁇ 110 ⁇ plane on its rolled surface.
  • the aggregation to ⁇ 110 ⁇ 001> orientation in electrical steel strip is achieved by utilizing a catastrophic phenomenon of grain growth called secondary recrystallization.
  • the control of secondary recrystallization essentially requires the control of a primary recrystallization texture and structure prior to the secondary recrystallization thereof and the control of an inhibitor, i.e. a fine precipitate, or an element of the intergranular segregation type.
  • the inhibitor inhibits the growth of any grains other than those having a ⁇ 110 ⁇ 001> orientation in the primary recrystallization texture and enables the selective growth of the grains having a ⁇ 110 ⁇ 001> orientation.
  • EP-A-0 321 695 relates to a method of producing grain-oriented electrical steel strip characterized by the addition of a prescribed amount of B or Ti.
  • EP-A-0 326 912 relates to a method of producing grain-oriented electrical steel strip characterized by the addition of a prescribed amount Ti.
  • EP-A-0 219 611 relates to a method of producing grain-oriented electrical steel strip characterized by the formation of (Si, Al) N prior to secondary recrystallization.
  • US-A-2 867 559 discloses a method of producing grain-oriented electrical steel strip characterized by controlling the average grain diameter of the intermediate-annealed strip prior to final cold rolling.
  • the present invention is devised in view of such a new finding by the inventors that the micro structure of a material after the step of annealing for decarburization but before the step of final annealing greatly affects upon the quality of secondary recrystallization and the magnetic properties of a product, and accordingly one object of the present invention is to provide a grain-oriented electrical steel strip having an extremely high magnetic flux density by controlling the primary recrystallization structure to a desired one.
  • a cold-rolled electrical steel strip is controlled so as to change the temperature and the time during the annealing step for decarburization so as to have a micro structure having an average grain size d ⁇ of greater than 15 ⁇ m, to 50 ⁇ m and a coefficient ⁇ * of deviation in grain size of not more than 0.6 (standard deviation of a distribution normalized by the average grain size d ⁇ ) between the annealing step for decarburization and the final annealing.
  • the material Prior to the annealing step for decarburization, the material might be subjected to a final high-reduction cold-rolling step for applying a reduction ratio of greater than 80%, thereby it is possible to obtain a grain-oriented electrical steel strip more excellent in the magnetic properties.
  • a grain-oriented electrical steel strip according to the present invention is obtained by a manufacturing process comprising the steps of: casting molten metal obtained by a conventionally used steel manufacturing process, into an ingot with the use of a continuously casting process or an ingot making process and then forming a slab, as necessary, through a blooming process; hot-rolling said ingot or slab so as to obtain a hot-rolled steel strip; annealing said hot-rolled steel strip as necessary; cold-rolling said hot-rolled steel strip by one time or by more than two times between which an intermediate annealing step is included, so as to form a cold-rolled steel strip having a final thickness; and annealing said cold-rolled steel strip for decarburization and then final annealing.
  • Preferred embodiments of the process defined in claim 1 are given in claim 2.
  • the present inventors paid attention to the micro structure of a material after the above-mentioned annealing step for decarburization so as to study the relationship between the recrystallization structure of a strip after the annealing step for decarburization (which strip will be hereinafter denoted as "decarburization-annealed strip”) and the magnetic properties (magnetic flux density) over a wide range with various kinds of view points, and found that the relationship therebetween is very close.
  • decarburization-annealed strip the recrystallization structure of a strip after the annealing step for decarburization
  • magnetic properties magnetic flux density
  • Figs. 1 and 2 show affection upon the magnetic flux density (B 8 value) of a product by an average diameter ( d ⁇ ) of a primary recrystallization grain (d is the diameter of the circle with the same area as the grain has.) and a coefficient ⁇ * of deviation in the diameter of the recrystallization grain which were obtained by image-analyzing the micro structure of a decarburization-annealed strip that was observed by an optical microscope (over entire area in the strip-thicknesswise direction).
  • Fig. 3 shows micro structures (strip-thicknesswise direction) of decarburization-annealed strips having average diameter ( d ⁇ ) of recrystallization grains and coefficients ⁇ * of deviation in the diameter of the recrystallization grains, which are different variously.
  • a slab consisting of 0.020 to 0.090 % (by weight) of C, 3.2 to 3.3 % of Si, 0.010 to 0.045 % of acid-soluble Al, 0.0030 to 0.0100 % of N, 0.0030 to 0.0300 % of S, 0.070 to 0.500 % of Mn and the balance of Fe and impurities, was heated up to 1,150 to 1,400°C, and then was hot-rolled into a hot-rolled strip (hot strip) having a thickness of 2.3 mm.
  • the hot-rolled strip was further subjected to a final high reduction cold-rolling step for applying a reduction ratio of about 88 % thereto after annealing the hot-rolled strip at a temperature in a temperature range of 900 to 1,200°C so as to obtain a cold-rolled strip having a final thickness of 0.285 mm, and the thus obtained cold-rolled strip was annealed for decarburization at a temperature of a temperature range of 830 to 1,000°C, and then was annealed after an annealing separation agent containing MgO as a main component being coated thereon.
  • Figs. 1 and 2 show such a fact that a satisfactory recrystallization and a product having satisfactory magnetic properties can be obtained by setting the average diameter d ⁇ of grain in a decarburization-annealed strip and the coefficient ⁇ * of deviation in the diameter in suitable ranges.
  • the inventors have considered that causes affecting upon the relationship between the average diameter d ⁇ of grain as well as the coefficient ⁇ * of deviation in the diameter of grain and occurrence of inferior secondary recrystallization or the magnetic flux density B 8 of a product are as follows although these are not always sure:
  • micro structure average diameter of grain, and distribution of grain diameters
  • texture the texture
  • inhibitor strength the like as factors affecting upon the secondary recrystallization, including the orientation of secondary recrystallization.
  • the average diameter of the primary recrystallization grain indirectly exhibits the texture and the distribution of diameters of grain.
  • the average diameter of grain in the decarburization-annealed strip itself is a value reversely proportional to the sum total of grain boundary areas (per unit area), and the intergranular energy give a drive force to the growth of grain in secondary recrystallization. Accordingly, the average diameter of grain in decarburization-annealed strip is considered as a parameter which is simultaneously descriptive of the texture, the distribution of grain diameters and the sum total of grain boundary areas which affect upon the secondary recrystallization.
  • the texture exhibits qualitative rates of crystal orientation ( ⁇ 110 ⁇ 001> oriented grain or the like), oriented grain facilitating the grain growth of secondary recrystallization grain ( ⁇ 111 ⁇ 112> oriented grain or the like) and other orientated grains, and further, the distribution of grain diameters affects upon the nucleation of secondary recrystallization grain, the ease of the grain growth and the nonuniformity of the grain growth. Accordingly, it can be considered that the average diameter d ⁇ of grain in the decarburization-annealed strip which is a parameter simultaneously descriptive of the texture, the distribution of grain diameters and the sum total of grain boundary areas, has a strong correlation to the orientation of secondary recrystallization grain.
  • the coefficient ⁇ * of deviation in the diameter of grain in the decarburization-annealed strip exhibits the nonuniformity of grain diameter, that is, the larger the coefficient ⁇ * of deviation in the diameter of grain, the harder the nucleation of secondary recrystallization grain and the growth of the grain become, and inferior secondary recrystallization seems to occur.
  • the coefficient ⁇ * of deviation in the diameter of grain has a close relationship with occurrence of inferior secondary recrystallization
  • the average diameter d ⁇ of grain in the decarburization-annealed strip has a close relationship with magnetic flux density of a product in the case of satisfactory secondary recrystallization. Accordingly, products having a high magnetic flux density (B 8 ) at a high yield rate can be manufactured by controlling the above-mentioned parameters in predetermined ranges.
  • the components of a slab used in the present invention are very important in order to stabilize the magnetic properties of a product, and include preferably 0.025 to 0.100 % by weight of C and 2.5 to 4.5 % of Si. Further, Al, N, Mn, S, Se, Sb, B, Cu, Si, Nb, Cr, Sn, Ti and the like can be added as elements for forming an inhibitor.
  • the heated temperature of the slab is preferably less than 1,300°C in view of the energy cost although it should not be limited specifically to this temperature.
  • the heated slab is then hot-rolled into a hot-rolled strip.
  • the hot-rolled strip after being annealed as necessary is then cold-rolled by one time or by more than two times between which an intermediate annealing is carried out, into a cold-rolled strip having a final thickness.
  • the reduction ratio in the final cold-rolling step is preferably greater than 80 %, although it should not be limited specifically to this value, in order to increase the magnetic flux density (B 8 ) of the product.
  • the cold-rolled strip is annealed for decarburization, and is coated with an annealing separation agent containing MgO as a main component before it is formed into a strip coil which is then annealed.
  • the average diameter d ⁇ of grain in the material before final annealing is set to greater than 15 ⁇ m, and the coefficient ⁇ * of deviation in the diameter of grain is set to less than 0.6.
  • a process of adjusting the number of primary recrystallization nucleuses by a reduction ratio in cold-rolling, grain diameters in a material to be cold-rolled and the like a process of controlling the grain growth during annealing for decarburization in which the strength of the inhibitor during annealing for decarburization is adjusted by manipulating the content amounts of elements forming the inhibitor, the heating temperature of the slab, the coiling temperature of the strip after hot-rolling, the temperature of annealing of the hot-rolled strip or the like, a process of controlling the grain growth by adjusting the temperature and time of the annealing for decarburization, and the like.
  • the average diameter d ⁇ of material grain before final annealing (primary recrystallization grain) to greater than 15 ⁇ m, and the coefficient ⁇ * of deviation in the diameter of grain to less than 0.6 by additionally annealing the material between the steps of annealing for decarburization and final annealing.
  • a core loss value is measured by passing the strip between primary and secondary core loss measuring coils, and then the diameter of primary recrystallization grain in the material is detected with the use of the relationship shown in Fig. 4.
  • the diameter of primary recrystallization grain is on-line measured, and then feed-back or feed-forward control for changing the temperature and time of annealing for decarburization are carried out so as to set the diameter of primary recrystallization grain to greater than 15 ⁇ m.
  • FIG. 5 shows the relationship between the temperature obtained during annealing for decarburization and the diameter of primary recrystallization grain.
  • the diameter of primary recrystallization grain is indicated with the use of a core loss value of a decarburization-annealed strip, the diameter of primary recrystallization grain can be known from Fig. 5 with the use of the relationship between the core loss value and the diameter of primary recrystallization grain in the decarburization-annealed strip, shown in Fig. 4.
  • Fig. 5 gives the diameters of primary recrystallization grain (Fig. 5 shows corresponding core loss values) which are obtained by variously changing the temperature of annealing while the time of annealing is fixed to 150 sec.
  • the diameter of primary recrystallization grain can be also controlled by changing the duration of annealing (strip feeding ratio) while fixing the annealing temperature to, for example, 850°C.
  • the material after primary recrystallization is preferably to nitrided in the atmosphere in which NH 3 having a concentration of higher than 1,000 ppm is mixed in mixture gas containing hydrogen gas and nitrogen gas while oxidation potential P H20 /P H2 being set to be equal to or less than 0.04 under a temperature range from 500 to 900°C and under, for example, such a condition that the strip is made to run, thereby to heighten the strength of the inhibitor during increase in temperature of final annealing, in view of stable manufacture of electrical steel strips.
  • Sulphurizing treatment can be also used for increasing the strength of the inhibitor.
  • the strength of the inhibitor should be lowered during annealing for decarburization in order to obtain a desired primary recrystallization structure by annealing for decarburization in a relative low temperature range (less than 800°C)
  • a relative low temperature range less than 800°C
  • the strength of the inhibitor is insufficient to stably carry out secondary recrystallization, it is required during final annealing to heighten the above-mentioned inhibitor strength.
  • inhibitor strengthening processes there has been known a process of setting the partial pressure of nitrogen in atmospheric gas for final annealing to a comparatively high value with steel containing Al.
  • the reason why the condition of primary recrystallization grain before final annealing is provided, is such that satisfactory magnetic properties can be obtained by additional heat-treatment after annealing for decarburization and before final annealing so as to adjust the average diameter d ⁇ of primary recrystallization grain to a value equal to or greater than 15 ⁇ m and the coefficient ⁇ * of deviation in the diameter of grain to a value equal to or less than 0.6.
  • a slab containing 0.054 wt.% of C, 3.25 wt.% of Si, 0.15 wt.% of Mn, 0.005 wt.% of S, 0.027 wt.% of acid-soluble Al and 0.0078 wt.% of N was heated up to 1,150°C, and was then hot-rolled into a hot-rolled strip having a thickness of 2.3 mm.
  • This hot-rolled strip was annealed at a temperature of 1,150°C and 900°C, and thereafter was cold-rolled at a cold-rolling reduction of about 88 % into a cold-rolled strip having a final thickness of 0.285 mm.
  • the cold-rolled strip was held at a temperature of 810°C for 150 sec.
  • decarburization-annealed strip was coated thereover with annealing separation agent having MgO as a main component, and was heated up to 1,200°C at a rate of 10°C/hour in the atmospheric gas containing 25 % of N 2 and 75 % of H 2 , and was then held at a temperature of 1,200°C for 20 hours in the atmospheric gas containing 100 % of H 2 in order to carry out final annealing.
  • annealing separation agent having MgO as a main component
  • a slab containing 0.058 wt.% of C, 3.28 wt.% of Si, 0.14 wt.% of Mn, 0.007 wt.% of S, 0.025 wt.% of acid-soluble Al and 0.0075 wt.% of N was heated up to a temperature of 1,150°C or 1,250°C, and then was hot-rolled into a hot-rolled strip having a thickness of 2.3 mm. This hot-rolled strip was held at a temperature of 1,150°C for 30 sec., and was then held at a temperature of 900°C for 30 sec. in order to be annealed.
  • the hot-rolled strip was cold-rolled at a reduction ratio of about 88% into a cold-rolled strip having a final thickness of 0.285 mm, which was then annealed for decarburization by being held at a temperature of 850°C for 150 sec.
  • decarburization-annealed strip is coated thereover with annealing separation agent containing MgO as a main component, heated up to 1,200°C at a rate of 10°C/hour in the atmospheric gas containing 25 % of N 2 and 75 % of H 2 , and was then held at a temperature of 1,200°C for 20 hours in the atmospheric gas containing 100 % of H 2 for final annealing.
  • annealing separation agent containing MgO as a main component
  • Table 3 shows the average diameter d ⁇ and diameter deviation coefficient ⁇ * of the steel strip (entire thickness in cross-section) together with the magnetic flux density B 8 of the product. TABLE 3 Presence of Additional Heat-Treat. Average Dia. d ⁇ ( ⁇ m) Deviat. Coeffi. in Dia. ⁇ * Magnetic Flux Density B 8 (T) Secondary Recryst. Rate (%) Remarks No 14 0.45 1.87 100 C.E. Yes 18 0.49 1.92 100 P.I.
  • a slab containing 0.056 wt.% of C, 3.27 wt.% of Si, 0.14 wt.% of Mn, 0.006 wt.% of S, 0.027 wt.% of acid-soluble Al and 0.0078 wt.% of N was heated up to a temperature of 1,150°C and then was hot-rolled into a hot-rolled strip having a thickness of 2.0 mm.
  • the hot-rolled strip was held at 1,120°C for 30 sec., then held at 900°C for 30 sec., for annealing, and was then cold-rolled at a reduction ratio of about 89 % into a cold-rolled strip having a final thickness of 0.220 mm, which was held at 830°C for 90 sec.
  • decarburization-annealed strip was coated thereover with annealing separation agent containing MgO as a main component, heated up to 880°C in the atmospheric gas containing 25 % of N 2 and 75 % of H 2 , and then heated up to 1,200°C from 880°C in the atmospheric gas containing 75 % of N 2 and 25 % of H 2 , and was then held at 1,200°C for 20 hours in the atmospheric gas containing 100 % of H 2 for final annealing. At this time, the rate of temperature rise up to 1,200°C was set to 10°C/hour and 25°C/hour.
  • the decarburization-annealed strip obtained under the conditions mentioned in the reference example 4 was coated thereover with annealing separation agent containing MgO as a main component, heated up to 1,200°C at a heating rate of 15°C/hour in the atmospheric gas of containing 25 % of N 2 and 75 % of H 2 and in the atmospheric gas containing 50 % of N 2 and 50 % of H 2 , and was then held at 1,200°C for 20 hours in the atmospheric gas containing 100 % of H 2 for final annealing.
  • annealing separation agent containing MgO as a main component
  • a slab containing 0.045 wt.% of C, 3.20 wt.% of Si, 0.065 wt.% of Mn, 0.023 wt.% of S, 0.08 wt.% of Cu and 0.018 wt.% of Sb was heated up to 1,300°C, and was thereafter hot-rolled into a hot-rolled strip having a thickness of 2.6 mm.
  • This hot-rolled strip was held at 900°C for three minutes for annealing, and was then cold-rolled at a reduction ratio of about 63 % into a cold-rolled strip having a thickness of 0.95 mm, and was held at 950°C for three minutes for intermediate annealing.
  • the cold-rolled strip was cold-rolled at a reduction ratio of 70 % so as to have a final thickness of 0.285 mm, and was held 810°C, 850°C and 890°C for 200 sec., respectively, in order to be annealed for decarburization.
  • the thus obtained decarburization-annealed strip was coated thereover with annealing separation agent containing MgO as a main component, was heated up to 1,200°C at a rate of 5°C/hour in the atmospheric gas containing 25 % of N 2 and 75 % of H 2 , and then was held at 1,200°C for 20 hours in the atmospheric gas containing 100 % of H 2 for final annealing.
  • a slab containing 0.05 % by weight of C, 3.25 % of Si, 0.028 % of acid-soluble Al, 0.0075 % of N, 0.007 % of S and 0.014 % of Mn was heated up to 1,150°C, and was hot-rolled in a conventional manner so as to obtain a hot-rolled strip having a thickness of 1.8 mm.
  • the hot-rolled strip was annealed at 1,150°C, and was cold-rolled into a cold-rolled strip having a thickness of 0.19 mm after pickling, which was then slitted into test pieces having a width of 60 mm, and core loss thereof were on-line measured in an experimental continuous annealing furnace.
  • the annealing was carried out by changing the annealing temperature in a range from 810 to 870°C and the annealing duration in a range from 90 to 150 sec. in the atmosphere of 75 % of H 2 and 25 % of N 2 having a dew point of 55°C.
  • the average grain diameter d ⁇ and diameter deviation coefficient ⁇ * of primary recrystallization grain before final annealing are controlled so as to stably manufacture a grain-oriented electrical steel strip having excellent magnetic properties.
  • the average diameter d ⁇ and the diameter deviation coefficient ⁇ * can be used as parameters for forecasting the magnetic flux density of the product, and therefore, the magnetic flux density of the product can be set to a desired value by adjusting, for example, the conditions of final annealing.

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Claims (2)

  1. Procédé de fabrication d'une bande en acier électrique à grain orienté présentant une densité de flux magnétique B8 ≥ 1,88 , comprenant les étapes consistant à :
    fournir une brame contenant 0,025 à 0,100 % en poids de C , 2,5 à 4,5 % de Si , si nécessaire un élément ou plus de deux éléments qui forment un inhibiteur et le reste étant du Fe plus les inévitables impuretés,
    laminer à chaud et laminer à froid en une seule fois ou en plus de deux fois entre lesquelles une étape de recuit intermédiaire est réalisée , en une bande laminée à froid présentant une épaisseur finale,
    effectuer un recuit pour décarburation de ladite bande laminée à froid pour une recristallisation primaire suivie d'un revêtement de ladite bande laminée à froid par un agent de séparation de recuit et
    effectuer un recuit final de la bande en acier ,
    caractérisé en ce que
    le diamètre de grain de recristallisation primaire du matériau (bande) est mesuré après achèvement de la recristallisation primaire pendant ladite étape de recuit pour décarburation et une commande automatique ou en direct pour modifier la température et la durée de recuit pendant ladite étape de recuit pour décarburation est réalisée selon le résultat de la mesure ; et
    le diamètre moyen d de grain de recristallisation primaire du matériau avant recuit final est établi à une valeur supérieure à 15 µm jusqu'à 50 µm et le coefficient σ* de variation du diamètre de grain est établi à une valeur qui n'est pas supérieure à 0,6 en utilisant au moins l'une des étapes consistant à :
    ajuster le nombre de noyaux de recristallisation primaire en commandant le taux de réduction du laminage à froid ou le diamètre de grain du matériau à laminer à froid; ajuster la résistance de l'inhibiteur en commandant au moins l'une des teneurs en éléments qui constituent ledit inhibiteur , la température de chauffage de ladite brame , la température de bobinage de la bande après laminage à chaud, et la température de recuit de la bande laminée à chaud ; ajuster la température et la durée de recuit pour décarburation ; et effectuer un recuit supplémentaire du matériau entre le recuit pour décarburation et le recuit final.
  2. Procédé selon la revendication 1, caractérisé en ce que le diamètre de grain du matériau (bande) est mesuré en direct après achèvement de la recristallisation primaire pendant ladite étape de recuit pour décarburation, la commande automatique ou en direct pour modifier la température et la durée de recuit pendant ladite étape de recuit pour décarburation étant réalisée suivant le résultat de la mesure.
EP90100231A 1989-01-07 1990-01-05 Procédé de fabrication d'une bande en acier électrique à grain orienté Expired - Lifetime EP0378131B1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP1778/89 1989-01-07
JP1001778A JPH0832929B2 (ja) 1989-01-07 1989-01-07 磁気特性の優れた一方向性電磁鋼板の製造方法
JP1086502A JPH0684524B2 (ja) 1989-04-05 1989-04-05 方向性電磁鋼板の１次再結晶焼鈍方法
JP86502/89 1989-04-05

Publications (3)

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EP0378131A2 EP0378131A2 (fr) 1990-07-18
EP0378131A3 EP0378131A3 (fr) 1992-09-30
EP0378131B1 true EP0378131B1 (fr) 1997-05-28

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EP (1) EP0378131B1 (fr)
DE (1) DE69030771T2 (fr)

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WO2013004747A1 (fr) 2011-07-06 2013-01-10 Thyssenkrupp Electrical Steel Gmbh Procédé de fabrication d'un produit plat en acier électrique à grains orientés destiné à des applications électrotechniques

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US5472521A (en) * 1933-10-19 1995-12-05 Nippon Steel Corporation Production method of grain oriented electrical steel sheet having excellent magnetic characteristics
JP2519615B2 (ja) * 1991-09-26 1996-07-31 新日本製鐵株式会社 磁気特性の優れた方向性電磁鋼板の製造方法
JP2620438B2 (ja) * 1991-10-28 1997-06-11 新日本製鐵株式会社 磁束密度の高い一方向性電磁鋼板の製造方法
JP2659655B2 (ja) * 1992-09-04 1997-09-30 新日本製鐵株式会社 磁気特性の優れた厚い板厚の方向性電磁鋼板
US6858095B2 (en) 1992-09-04 2005-02-22 Nippon Steel Corporation Thick grain-oriented electrical steel sheet exhibiting excellent magnetic properties
US5665178A (en) * 1995-02-13 1997-09-09 Kawasaki Steel Corporation Method of manufacturing grain-oriented silicon steel sheet having excellent magnetic characteristics
KR100241167B1 (ko) * 1995-04-18 2000-03-02 에모토 간지 연속열간압연에 있어서의 강편접합부의 압연방법
EP0947597B2 (fr) * 1998-03-30 2015-06-10 Nippon Steel & Sumitomo Metal Corporation Procédé de fabrication d'une tôle d'acier à grains orientés presentant d'excellentes caracteristiques magnétiques
KR100501002B1 (ko) * 2000-05-24 2005-07-18 주식회사 포스코 방향성 전기강판의 제조방법
KR100501003B1 (ko) * 2000-06-16 2005-07-18 주식회사 포스코 방향성 전기강판의 제조방법
CN110457729B (zh) * 2019-05-17 2023-04-14 陕西飞机工业（集团）有限公司 半封闭结构钢热处理零件的优化方法、装置及轴类零件

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EP0321695A2 (fr) * 1987-11-20 1989-06-28 Nippon Steel Corporation Procédé pour la fabrication de tôles d'acier électrique à grains orientés et à densité de flux élevée
EP0326912A2 (fr) * 1988-02-03 1989-08-09 Nippon Steel Corporation Procédé de fabrication d'une tôle en acier électrique à grain orienté présentant une haute densité de flux

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EP0321695A2 (fr) * 1987-11-20 1989-06-28 Nippon Steel Corporation Procédé pour la fabrication de tôles d'acier électrique à grains orientés et à densité de flux élevée
EP0326912A2 (fr) * 1988-02-03 1989-08-09 Nippon Steel Corporation Procédé de fabrication d'une tôle en acier électrique à grain orienté présentant une haute densité de flux

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013004747A1 (fr) 2011-07-06 2013-01-10 Thyssenkrupp Electrical Steel Gmbh Procédé de fabrication d'un produit plat en acier électrique à grains orientés destiné à des applications électrotechniques
DE102011107304A1 (de) 2011-07-06 2013-01-10 Thyssenkrupp Electrical Steel Gmbh Verfahren zum Herstellen eines kornorientierten, für elektrotechnische Anwendungen bestimmten Elektrostahlflachprodukts

Also Published As

Publication number Publication date
DE69030771D1 (de) 1997-07-03
EP0378131A3 (fr) 1992-09-30
DE69030771T2 (de) 1997-09-11
EP0378131A2 (fr) 1990-07-18

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