EP0345936A1 - Verfahren zur Veredelung der magnetischen Bereiche von elektrischen Stählen - Google Patents

Verfahren zur Veredelung der magnetischen Bereiche von elektrischen Stählen Download PDF

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Publication number
EP0345936A1
EP0345936A1 EP89304300A EP89304300A EP0345936A1 EP 0345936 A1 EP0345936 A1 EP 0345936A1 EP 89304300 A EP89304300 A EP 89304300A EP 89304300 A EP89304300 A EP 89304300A EP 0345936 A1 EP0345936 A1 EP 0345936A1
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Prior art keywords
steel
contaminant
coating
base coating
annealing
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EP89304300A
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French (fr)
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EP0345936B1 (de
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Stuart Leslie Ames
Jeffrey Michael Breznak
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Allegheny Ludlum Corp
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Allegheny Ludlum Corp
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Priority claimed from US07/205,711 external-priority patent/US4904313A/en
Priority claimed from US07/206,051 external-priority patent/US4904314A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
    • H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
    • H01F1/147—Alloys characterised by their composition
    • H01F1/14766—Fe-Si based alloys
    • H01F1/14775—Fe-Si based alloys in the form of sheets
    • H01F1/14783—Fe-Si based alloys in the form of sheets with insulating coating
    • 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
    • C21D8/1294—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties involving a localized treatment
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C10/00—Solid state diffusion of only metal elements or silicon into metallic material surfaces
    • C23C10/04—Diffusion into selected surface areas, e.g. using masks
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C26/00—Coating not provided for in groups C23C2/00 - C23C24/00

Definitions

  • This invention relates to a method for improving core loss by refining the magnetic domain wall spacing of electrical steels, particularly electrical steel sheet or strip.
  • Grain-oriented silicon steel is conventionally used in electrical applications, such as power transformers, distribution transformers, generators, and the like.
  • the ability of the steel to permit cyclic reversals of the applied magnetic field with only limited energy loss is a most important property. Reductions of this loss, which is termed "core loss”, is desirable.
  • the Goss secondary recrystallization texture (110) [001] in terms of Miller's indices, results in improved magnetic properties, particularly permeability and core loss over nonoriented silicon steels.
  • the Goss texture refers to the body-centered cubic lattice comprising the grain or crystal being oriented in the cube-on-edge position.
  • the texture or grain orientation of this type has a cube edge parallel to the rolling direction and in the plane of rolling, with the (110) plane being in the sheet plane.
  • steels having this orientation are characterized by a relatively high permeability in the rolling direction and a relatively low permeability in a direction at right angles thereto.
  • typical steps include providing a melt having of the order of 2-4.5% silicon, casting the melt, hot rolling, cold rolling the steel to final gauge e.g., of 7 to 14 mils (0.178 to 0.356 mm), typically of 7 or 9 mils (0.178 or 0.229 mm), with an intermediate annealing when two or more cold rollings are used, decarburizing the steel, applying a refractory oxide base coating, such as a magnesium oxide coating, to the steel, and final texture annealing the steel at elevated temperatures in order to produce the desired secondary recrystallization and purification treatment to remove impurities such as nitrogen and sulfur.
  • the development of the cube-on-edge orientation is dependent upon the mechanism of secondary recrystallization wherein during recrystallization, secondary cube-on-edge oriented grains are preferentially grown at the expense of primary grains having a different and undesirable orientation.
  • sheet and “strip” are used interchangeably and mean the same unless otherwise specified.
  • first, regular or conventional grain-oriented silicon steel, and second, high permeability grain-oriented silicon steel are generally characterized by permeabilities of less than 1850 at 10 Oersted (796 A/m) with a core loss of greater than 0.400 watts per pound (WPP) (0.88 watts/kg)at 1.5 Tesla at 60 Hertz for nominally 9-mil (0.229mm) material.
  • WPP watts per pound
  • High permeability grain-oriented silicon steels are characterized by higher permeabilities which may be the result of compositional changes alone or together with process changes.
  • high permeability silicon steels may contain nitrides, sulfides, and/or borides which contribute to the precipitates and inclusions of the inhibition system which contributes to the properties of the final steel product.
  • high permeability silicon steels generally undergo cold reduction operations to final gauge wherein a final heavy cold reduction of the order of greater than 80% is made in order to facilitate the grain orientation. While such higher permeability materials are desirable, such materials tend to produce larger magnetic domains than conventional material. Generally, larger domains are deleterious to core loss.
  • domain size and thereby core loss values of electrical steels may be reduced is if the steel is subjected to any of various practices designed to induce localized strains in the surface of the steel.
  • Such practices may be generally referred to as "domain refining by scribing" and are performed after the final high temperature annealing operation. If the steel is scribed after the final texture annealing, then there is induced a localized stress state in the texture-annealed sheet so that the domain wall spacing is reduced.
  • These disturbances typically are relatively narrow, straight lines, or scribes, generally spaced at regular intervals. The scribe lines are substantially transverse to the rolling direction and typically are applied to only one side of the steel.
  • the method includes imparting a strain to the sheet, forming an intruder on the grain-oriented sheet, the intruder being of a different component or structure than the electrical sheet and doing so either prior to or after straining and thereafter annealing such as in a hydrogen reducing atmosphere to result in imparting the intruders into the steel body.
  • Numerous metals and nonmetals are identified as suitable intruder materials.
  • Japanese Patent Document 61-133321A discloses removing surface coatings from final texture annealed magnetic steel sheet, forming permeable material coating on the sheet and heat treating to form material having components or structure different than those of the steel matrix at intervals which provide heat resistant domain refinement.
  • Japanese Patent Document 61-139-679A discloses a process of coating final texture annealed oriented magnetic steel sheet in the form of linear or spot shapes, at intervals with at least one compound selected from the group of phosphoric acid, phosphates, boric acid, borates, sulfates, nitrates, and silicates, and thereafter baking at 300-1200°C, and forming a penetrated body different from that of the steel to refine the magnetic domains.
  • Japanese Patent Document 61-284529A discloses a method of removing the surface coatings from final texture annealed magnetic steel sheets at intervals, coating one or more of zinc, zinc alloys, and zincated alloy at specific coating weights, coating with one or more of metals having a lower vapor pressure than zinc, forming impregnated bodies different from the steel in composition or in structure at intervals by heat treatment or insulating film coating treatment to refine the magnetic domains.
  • Japanese Patent Document 62-51202 discloses a process for improving the core loss of silicon steel by removing the forsterite film formed after final finish annealing, and adhering different metal, such as copper, nickel, antimony by heating.
  • What is needed is a method for refining the magnetic domain wall spacing of grain-oriented silicon steel, having a base coating e.g., of forsterite, thereon, which is heat resistant.
  • the method should be compatible with conventional processing of regular and high permeability silicon steels and should use the thermally insulative coating, e.g., the forsterite base coating, on the sheet to facilitate the domain refinement. Still further, the method should be useful with numerous techniques including conventional methods for removing the base coating in selected patterns
  • the invention provides a method and a semi-finished steel sheet or strip product as defined in the appended claims.
  • a method for refining the magnetic domain wall spacing of grain-oriented silicon steel sheet or strip having an insulation base coating including removing portions of the base coating to expose a line pattern of the underlying silicon steel, and applying a metallic contaminant to the silicon steel.
  • the metallic contaminant may be copper, tin, nickel, zinc or antimony, or combinations or compounds thereof.
  • the exposed steel is free of thermal and plastic stresses and is not dependent on such stresses to be effectively domain refined.
  • the steel and contaminant thereon are annealed at time and temperature of 1400 °F (760°C) or more in a protective atmosphere to diffuse sufficient and controlled amounts of contaminant into the exposed steel to produce lines of permanent pores to effect heat resistant domain refinement and reduced core loss in substantially stress-free steel.
  • a barrier coating of phosphorus or silicate, or combinations or compounds thereof, is applied to the steel sheet for sealing the base coating prior to applying said metallic contaminant.
  • the method of the present invention relates to a method for refinement of the domain structure of grain-oriented silicon steel sheet having relatively large grain sizes by controlled surface chemical contamination.
  • the method takes final textured annealed silicon steel as the starting sheet material, having the electrically and thermally insulating base coating in place, and then by any of numerous techniques, locally removes the coating to expose the bare metal. No plastic strain or stress of any sort needs to be imposed on the metal and thereafter the exposed bare metal is contaminated by other materials on the areas of the exposed metal pattern.
  • the steel is then annealed to diffuse or alloy the contaminant into the iron-silicon steel sheet product.
  • the resulting domain refinement is heat resistant as it survives stress relief annealing.
  • the starting material for the chemical striping process of the present invention is final textured annealed grain-oriented silicon steel having an insulative coating in place.
  • Such an insulative coating can be the conventional base coating, also called forsterite or mill glass coating.
  • the as-­scrubbed final texture annealed grain-oriented silicon steels may be used.
  • Such steels may be of the regular or conventional grain-oriented silicon steels or of high permeability grain-oriented silicon steels.
  • the particular compositions of such steels are not critical to the present invention and they may be conventional compositions.
  • the steel melts initially contained the nominal composition as follows: C N Mn S Si Cu B Fe Steel 1 .030 ⁇ 50ppm .038 .017 3.15 .30 10ppm Bal. Steel 2 .030 50ppm .07 .022 3.15 .22 -- Bal. Steel 3 .038 45ppm .078 .026 3.25 .25 5-6ppm Bal.
  • Steel 1 is a high permeability grain-oriented silicon steel and Steel 2 is a conventional grain-­oriented silicon steel and Steel 3 is a modified conventional grain-oriented silicon steel. As used herein, all compositions are by weight percent, unless otherwise specified.
  • Steels 1, 2 and 3 were produced by casting, hot rolling, normalizing, cold rolling to final gauge with an intermediate annealing when two or more cold rolling stages were used, decarburizing, coating with MgO, and final texture annealing to achieve the desired secondary recrystallization of cube-on-edge orientation.
  • a refractory oxide base coating containing primarily magnesium oxide was applied before final texture annealing at elevated temperature; such annealing caused a reaction at the steel surface to create a forsterite base coating.
  • the steel melts of Steels 1, 2, and 3 initially contained the nominal compositions recited above, after final texture annealing, the C, N and S were reduced to trace levels of less than about 0.001% by weight.
  • the coating it is important that portions of the coating be removed to expose a line or stripe pattern in the underlying silicon steel. How the coating is removed is not critical to the present invention except that the underlying steel need not be subjected to any mechanical, thermal, or other stresses and strains as a result of the coating removal operation. In other words, the exposed steel must be free of any thermal and plastic stresses prior to any subsequent steps of applying the metallic contaminant.
  • An advantage of the present invention is that any of various techniques may be used to remove the selected portions of the base coating. For example, conventional mechanical scribing or laser means may be used to develop a controlled pattern of markings on the strip surface.
  • the line or stripe pattern selected for the removed base coating may be conventional patterns used in prior art scribing techniques.
  • the pattern may comprise removing the coating in generally parallel lines substantially transverse to the rolling direction of the steel having a line width and spacing as may be conventional.
  • Other patterns may also be useful, depending on whether the grain-oriented silicon steel is of the cube-on-edge, cube-on-face, or other orientation.
  • the exposed silicon steel would be plated or coated by selected metals and metal alloys.
  • the metals are selected such that they have a diffusion rate slower than iron in silicon steels.
  • the metals and metal alloys suitable for the present invention are referred to as contaminant or diffuser materials.
  • contaminant refers to those certain suitable metal and metal alloys selectively applied to the exposed areas of steel sheet in accordance with this invention. It has been found that various metallic contaminants may be used selected from copper, tin, nickel, zinc or antimony, or combinations or compounds thereof. The metallic contaminants may be applied as a coating to the silicon steel using various conventional means such as electroless deposition or electrolytic plating.
  • the metallic contaminant can only be applied in the selected line pattern or stripes which conform to the pattern of base coating removal. What is important at this point is that the base glass insulation on the silicon steel facilitates selective deposition of the metallic contaminant in the predetermined or preselected pattern.
  • the silicon steel having the selected portions of base coating removed and having the metallic contaminant applied is thereafter annealed at a time and temperature in a protective atmosphere to diffuse sufficient and controlled amounts of contaminant into the exposed steel to produce permanent pores to effect heat resistant domain refinement and reduced core loss.
  • the annealing has the effect of a diffusion anneal to cause minor alloying of the metallic contaminant with the iron-­silicon steel sheet to effect heat resistant domain refinement.
  • the annealing temperature ranges from about 1400°F (760°C) or more and may range up to 2100°F (1150°C). Preferably, the temperatures range up to 1800°F (982°C) and more preferably, from about 1400 to 1700°F (760 to 927°C).
  • the anneal temperature be at least equal to or greater than the temperature that would normally be used for a stress relief anneal in order that the property effects developed would be stable with respect to any subsequent lower temperature treatment such as a stress relief anneal (SRA).
  • SRA stress relief anneal
  • the time for the anneal may range up to 20 hours and preferably may range from 30 minutes to 5 hours at a temperature sufficient to produce the magnetic domain refining.
  • the diffusion anneal should be higher than a conventional stress relief anneal of about 1425°F (774°C) which may be used by transformer manufacturers following fabrication.
  • Temperatures of the order of up to 1650°F (899°C) are sufficient to effect the heat resistant domain refinement without requiring an additional separator coating to prevent adjacent coil laps from thermally welding together during the annealing. Lower temperature anneals may also be successful.
  • substantially complete homogeneity is a highly desirable condition for soft magnetic materials. It has been found that proper time and temperature develops and stabilizes the permanent pores and further diffuses the contaminants into the steel to provide a substantially homogeneous steel sheet throughout the steel thickness. Generally, annealing at the higher temperatures facilitates homogeneity.
  • the strip may be annealed either in coil form or as a strand anneal of the continuously moving strip following the application of the metallic contaminant.
  • Epstein packs of nominally 8-mil (0.2mm) high permeability grain-oriented silicon steel sheet having the composition of steel 1 were mechanically scribed in the as-scrubbed condition.
  • the scribing effectively removed portions of the base coating in a pattern of substantially parallel lines substantially transverse to the rolling direction of the steel strip.
  • Each Epstein pack had twelve (12) strips, and each strip was 3 cm wide and had the scribe lines spaced at about 5 mm intervals.
  • a stress relief anneal at 1500°F (816°C) for two hours was performed.
  • the samples were then electrolytically plated with copper using the copper solution described in Table I and subsequently annealed at 1650°F (899°C) for 5 hours in a protective atmosphere to diffuse the metallic contaminant into the silicon steel sheet body. Percentages in parentheses indicate change compared to initial properties.
  • the magnetic properties were determined in a conventional manner for Epstein packs. TABLE II Epstein Pack Initial As-Scrubbed Mechanically Scribed 2 hr. at 1500°F Stress-Relief Anneal Chemically-Striped (Copper) + 1650°/5 hr.
  • the samples demonstrate a permanent core loss improvement indicating a heat-resistant domain refinement in each sample.
  • Such samples confirm that thermal or plastic deformation of the exposed silicon steel plays no role in heat resistant domain refinement.
  • Figure 1 is a Scanning Electron Microscope photomicrograph of a groove, i.e. the silicon steel exposed through the base coating, filled with copper after plating the sample with copper.
  • Figure 2 is a 150X photograph of an x-ray map showing copper in the line pattern of the silicon steel sample.
  • Single-strip Epstein samples 8 mils (0.2mm) thick by 3 cm wide of the steel composition of Example I were subjected to a chemical pickling in HCl-1% HF acid to remove all of the insulative base coating from the texture annealed strips.
  • a plastic stencil with slits was attached to the steel surface, such that the pattern of slits formed substantially parallel lines substantially transverse to the rolling direction of the steel strip as in Example I.
  • Each sample with the stencil thereon was electroplated with copper as described in Example I, and then annealed at 1650°F (899°C) for 2 hours (with the stencil removed) to diffuse the metallic contaminant into the silicon steel body. Percentages in parentheses indicate changes compared to original properties.
  • Results shown in Table III show considerably improved properties of core loss after the diffusion anneal although the samples at no stage were subjected to a plastic deformation or stress.
  • the improved properties demonstrate unequivocally that plastic deformation plays no role in domain refining by chemical striping in accordance with the present invention.
  • Single strips of a high permeability grain-oriented silicon steel of the steel described in Examples I and II were mechanically scribed or in some cases electrically discharge scribed in the as-scrubbed condition.
  • the scribing effectively removed portions of the base coating in a pattern of substantially parallel lines substantially transverse to the rolling direction of the steel strip.
  • the lines were about 3 mm wide on single strip 8-mil (0.2 mm) Epstein samples and spaced at about 5 mm intervals
  • the samples were then electrolytically plated with various metallic contaminants from the plating solutions listed in Table I. the plating resulted in the grooves in the base coating being at least half filled with the metallic contaminant, as judged under a microscope. After plating, the samples were diffusion annealed as indicated in a substantially hydrogen atmosphere.
  • the steels exhibited improvement in core loss properties at both 1.5 and 1.7 Tesla with little or no loss in permeability. Since the samples were heated at temperature above typical 1425°F (774°C) stress relief annealing, the core loss improvements were permanent with respect to heating at that temperature. In other words, the improvements were "heat proof".
  • Epstein packs were then subjected to a further anneal at 2100°F (1150°C) for 2 hours or 10 hours as indicated. Percentages in parentheses indicate change compared to initial properties. TABLE V Sample No. Initial Properties Chemically-Striped with 1650°F/5 hr.
  • the metal contaminants chosen will perform as expected if the diffusion rates are slower than the self-diffusion rate of iron in the ferrous base alloy. Furthermore, the slower the rate of the diffusion through iron, the more suitable the metal may be as a contaminant to produce the permanent porosity. For example, copper is of the order of 4 times slower than iron in diffusion through iron. Nickel is of the order of 500 times slower. Such metallic elements having slower diffusion rates in iron should result in the Kirkendall porosity phenomenon and the benefits of the present invention.
  • the use of an additional sealant coating or barrier coating applied to the forsterite before applying the metallic contaminant to the exposed silicon steel stripes results in a striking improvement in consistency and reproduceability to effect heat resistant domain refinement
  • the main purpose of introducing the barrier coating in the process is to seal the pores and cracks in the forsterite coating.
  • Table VI identifies several coatings which are believed to be useful in acting as a barrier coating in accordance with the present invention. The similarity between all of these coatings is that they are all water soluble and cure at relatively low temperatures.
  • these barriers coatings contain phosphorus or silicates, or combinations or compounds thereof as the primary constituent of the coating.
  • the coating primary constituent is a metal phosphate or metal silicate, and more preferably, the coating should be one that when cured sets up essentially as a magnesium phosphate layer.
  • TABLE VI Designation Barrier Coating and Conditions Concentration SC Phosphoric Acid (85%) 202 gm/l Magnesium Oxide 22 gm/l Nalcoag (1050) 318 ml/l Chromic Trioxide 46 gm/l Water Balance Cured: 1000°F (538 o C) - 1 min.(air) CS Sodium Silicate (40-42 Be) 500 ml/l Water Balance Cured: 800°F (427 o C) - 1 min.(air) PS Phosphoric Acid (85%) 120 gm/l Magnesium Oxide 18 gm/l Kasil #1 22 gm/l Ammonium Hydroxide (58%) 21 ml/l Chromic Trioxide .34 gm/l Kunol (2%) 1.0 ml/l Water Balance
  • Tests were performed to demonstrate the effect of the barrier coating on enhancing the heat resistant domain refinement process. All of the samples were obtained from various heats of nominally 8-mil (0.2mm) gauge silicon steel having the typical composition of Steel 1. Single strips of Steel 1 were mechanically scribed into the as-scribed condition. The scribing effectively removed portions of the base coating in a pattern of substantially parallel lines substantially transverse to the rolling direction of the steel strip. The lines were about 0.25 mm wide and spaced at about 5 mm intervals. Each sample was then coated with barrier coating "P" from Table VI after the step of removing the base coating. All of the samples were thereafter electroplated with either zinc or copper from the plating solution listed in Table I. The magnetic properties are Epstein single strip results from strips of 30 x 3 cm.
  • Table VII presents data which shows that most of the samples had an attractive improvement in core loss averaging of the order of 10 to 12%.
  • samples from the same batches of material were capable of providing 15-20% improvement in core losses by conventional mechanical scribing techniques.
  • a further advantage of the present invention is that such improvement in core loss may be the result of heat resistant domain refinement.
  • the data of Table VIII show that the domain refining process of the present invention can reduce the core loss in 8-mil (0.2mm) gauge material of Steel 1 by up to 11% when compared to initial properties. The best improvement was obtained with the contaminant copper.
  • the core loss is 7-mil [0.18mm) 1 material of Steel 2 was reduced by about 5° at 1.5T and by 5% at 1.7T.
  • the core loss in 7-mil (0.18mm) material of Steel 3 was reduced by about 7% at 1.5T and by about 4% at 1.7T.
  • the magnetic properties are Epstein single strip results of nominally 8-mil (0.2 mm) strip of 30 x 3 cm. Percentages in parentheses indicate change compared to original properties.
  • the barrier coating not only seals the pores and cracks in the base coating of the grain-oriented silicon steel, but it also acts synergistically with the major contaminant in the striped area of the steel during and after the diffusion anneal.
  • zinc or nickel-tin as the major contaminant phosphorus was evident in the permanent defect produced in the steel.
  • a further advantage of the method of the present invention is the ability to remove portions of the base coating to expose a pattern of the underlying silicon steel such as in lines substantially transverse to the rolling direction by any conventional or unconventional means provided that the steel exposed through the base coating is free from thermal and plastic stresses.
  • the barrier coating enhances the core loss improvements and the reproduceability of such improvements.
  • An advantage of the present invention is that a semifinished sheet product having a barrier coating and metallic contaminant can be produced for subsequent annealing by the customer before or after fabricating into transformer cores.

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EP89304300A 1988-06-10 1989-04-28 Verfahren zur Veredelung der magnetischen Bereiche von elektrischen Stählen Expired - Lifetime EP0345936B1 (de)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US07/205,711 US4904313A (en) 1988-06-10 1988-06-10 Method of producing stable magnetic domain refinement of electrical steels by metallic contaminants
US07/206,051 US4904314A (en) 1988-06-10 1988-06-10 Method of refining magnetic domains of barrier-coated electrical steels using metallic contaminants
US206051 1988-06-10
US205711 1988-06-10

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EP0345936A1 true EP0345936A1 (de) 1989-12-13
EP0345936B1 EP0345936B1 (de) 1995-08-30

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EP (1) EP0345936B1 (de)
JP (1) JPH02118023A (de)
BR (1) BR8902713A (de)
DE (1) DE68924000T2 (de)
MX (1) MX166083B (de)

Cited By (4)

* Cited by examiner, † Cited by third party
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EP0869190A1 (de) * 1997-03-26 1998-10-07 Kawasaki Steel Corporation Kornorientiertes Elektrostahlblech mit sehr niedrigen Eisenverlusten und dessen Herstellung
GB2533446A (en) * 2014-07-18 2016-06-22 Gm Global Tech Operations Llc Metal sheet and method for its treatment
US10297384B2 (en) 2015-11-10 2019-05-21 GM Global Technology Operations LLC Method for processing a plate workpiece
US10344349B2 (en) 2013-07-24 2019-07-09 GM Global Technology Operations LLC Method for treating sheet metal

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US3932235A (en) * 1973-07-24 1976-01-13 Westinghouse Electric Corporation Method of improving the core-loss characteristics of cube-on-edge oriented silicon-iron
US3990923A (en) * 1974-04-25 1976-11-09 Nippon Steel Corporation Method of producing grain oriented electromagnetic steel sheet
EP0193324A2 (de) * 1985-02-22 1986-09-03 Kawasaki Steel Corporation Kornorientierte Siliciumstahlbleche mit ganz niedrigen Eisenverlusten

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IT1182608B (it) * 1984-10-15 1987-10-05 Nippon Steel Corp Lamiera di acciaio elettrico a grana orientata avente una bassa perdita di potenza e metodo per la sua fabbricazione
JPS61133321A (ja) * 1984-11-30 1986-06-20 Nippon Steel Corp 超低鉄損方向性電磁鋼板の製造方法
JPS6319572A (ja) * 1986-07-12 1988-01-27 Fujikura Ltd 磁気センサ

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Cited By (7)

* Cited by examiner, † Cited by third party
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EP0869190A1 (de) * 1997-03-26 1998-10-07 Kawasaki Steel Corporation Kornorientiertes Elektrostahlblech mit sehr niedrigen Eisenverlusten und dessen Herstellung
US6103022A (en) * 1997-03-26 2000-08-15 Kawasaki Steel Corporation Grain oriented electrical steel sheet having very low iron loss and production process for same
US6364963B1 (en) 1997-03-26 2002-04-02 Kawasaki Steel Corporation Grain oriented electrical steel sheet having very low iron loss and production process for same
US10344349B2 (en) 2013-07-24 2019-07-09 GM Global Technology Operations LLC Method for treating sheet metal
GB2533446A (en) * 2014-07-18 2016-06-22 Gm Global Tech Operations Llc Metal sheet and method for its treatment
US10309004B2 (en) 2014-07-18 2019-06-04 GM Global Technology Operations LLC Metal sheet and method for its treatment
US10297384B2 (en) 2015-11-10 2019-05-21 GM Global Technology Operations LLC Method for processing a plate workpiece

Also Published As

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JPH02118023A (ja) 1990-05-02
EP0345936B1 (de) 1995-08-30
MX166083B (es) 1992-12-17
DE68924000T2 (de) 1996-03-14
BR8902713A (pt) 1990-01-23
DE68924000D1 (de) 1995-10-05

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