Grain-oriented electrical steel sheet, stacked transformer core using the same, and method for producing stacked core

{
  "publication_number": "US11495378B2",
  "country": "US",
  "kind": "B2",
  "title": "Grain-oriented electrical steel sheet, stacked transformer core using the same, and method for producing stacked core",
  "abstract": "A grain-oriented electrical steel sheet for a stacked transformer core. The steel sheet having a sheet thickness t, where t and an iron loss deterioration ratio obtained by subjecting the steel sheet under elliptic magnetization satisfy the following relations: (i) when t≤0.20 mm, the iron loss deterioration ratio is 85% or less; (ii) when 0.20 mm<t<0.27 mm, the iron loss deterioration ratio is 80% or less; and (iii) when 0.27 mm≤t, the iron loss deterioration ratio is 75% or less. The iron loss deterioration ratio is calculated from ((W A −W B)/W B)×100, where W A is iron loss under 50 Hz elliptic magnetization of 1.7 T in a rolling direction and 1.0 T in a direction orthogonal to the rolling direction, and W B is iron loss under 50 Hz alternating magnetization of 1.7 T in the rolling direction.",
  "claims": [
    "1. A grain-oriented electrical steel sheet for a stacked core of a transformer, the steel sheet having a sheet thickness t and an iron loss deterioration ratio defined by formula (1): ((W A −W B)/ W B)×100 (1) where W A is iron loss of the steel sheet under 50 Hz elliptic magnetization of 1.7 T in a rolling direction and 1.0 T in a direction orthogonal to the rolling direction, and W B is iron loss of the steel sheet under 50 Hz alternating magnetization of 1.7 T in the rolling direction, wherein, when t≤0.20 mm, the iron loss deterioration ratio is 85% or less, when 0.20 mm<t<0.27 mm, the iron loss deterioration ratio is 80% or less, and when t≥0.27 mm, the iron loss deterioration ratio is 75% or less.",
    "2. The grain-oriented electrical steel sheet according to claim 1, wherein a plurality of linear strains extending in a direction intersecting the rolling direction are formed on a surface of the steel sheet, and a width w of closure domains formed by the strains, a diameter R of secondary recrystallized grains in the steel sheet, and an average β angle of the secondary recrystallized grains in the steel sheet satisfy formula (2): Sin β+4 t/R +(w/a/ √2)×10 −3 ≥0.080, (2) where β is the average β angle (°) of the secondary recrystallized grains, t is the thickness (mm) of the steel sheet, R is the diameter (mm) of the secondary recrystallized grains, w is the width (μm) of the closure domains, and a is intervals (mm) between the plurality of linear strains extending in the direction intersecting the rolling direction.",
    "3. The grain-oriented electrical steel sheet according to claim 2, wherein the steel sheet has a magnetic flux density B8 that is 1.94 T or more at a magnetizing force of 800 A/m, and the diameter R of the secondary recrystallized grains is 40 mm or more.",
    "4. The grain-oriented electrical steel sheet according to claim 1, wherein the steel sheet has a magnetic flux density B8 that is 1.94 T or more at a magnetizing force of 800 A/m, and the diameter R of the secondary recrystallized grains is 40 mm or more.",
    "5. A stacked core of a transformer, the stacked core being formed from the grain-oriented electrical steel sheet according to claim 1.",
    "6. A method for producing a stacked core of a stacked core transformer, the method allowing a building factor to be reduced, the building factor being obtained by dividing a value of iron loss of the stacked core transformer by a value of iron loss of grain-oriented electrical steel sheets used as a raw material of the stacked core, the method comprising: stacking the grain-oriented electrical steel sheets to form the stacked core, wherein a sheet thickness t of each of the grain-oriented electrical steel sheets and an iron loss deterioration ratio obtained when the grain-oriented electrical steel sheets are subjected to elliptic magnetization satisfy the following relationships: when t≤0.20 mm, the iron loss deterioration ratio is 85% or less; when 0.20 mm<t<0.27 mm, the iron loss deterioration ratio is 80% or less; and when 0.27 mm≤t, the iron loss deterioration ratio is 75% or less, and the iron loss deterioration ratio is defined by formula (1) below: ((W A −W B)/ W B)×100 (1) where, in formula (1): W A is iron loss under 50 Hz elliptic magnetization of 1.7 T in a rolling direction and 1.0 T in a direction orthogonal to the rolling direction, and W B is iron loss under 50 Hz alternating magnetization of 1.7 T in the rolling direction.",
    "7. The method for producing a stacked core according to claim 6, wherein each of the steel sheets includes: secondary recrystallized grains in each of the steel sheets, and a plurality of linear strains that is formed on a surface of each of the steel sheets, the plurality of linear strains extending in a direction intersecting the rolling direction, and a width w of closure domains formed by the strains, a diameter R of the secondary recrystallized grains, and an average β angle of the secondary recrystallized grains satisfy the relation represented by the following formula (2): Sin β+4 t/R +(w/a/ √2)×10 −3 ≥0.080, (2) where, in formula (2): β: the average β angle (°) of the secondary recrystallized grains, t: the thickness (mm) of each of the steel sheets, R: the diameter (mm) of the secondary recrystallized grains, w: the width (m) of the closure domains, and a: intervals (mm) between the plurality of linear strains extending in the direction intersecting the rolling direction.",
    "8. The method for producing a stacked core according to claim 7, wherein each of the steel sheets has a magnetic flux density B8 that is 1.94 T or more at a magnetizing force of 800 A/m, and the diameter R of the secondary recrystallized grains is 40 mm or more.",
    "9. The method for producing a stacked core according to claim 6, wherein each of the steel sheets has a magnetic flux density B8 that is 1.94 T or more at a magnetizing force of 800 A/m, and the diameter R of the secondary recrystallized grains is 40 mm or more.",
    "10. A stacked core of a transformer, the stacked core being formed from the grain-oriented electrical steel sheet according to claim 2.",
    "11. A stacked core of a transformer, the stacked core being formed from the grain-oriented electrical steel sheet according to claim 4.",
    "12. A stacked core of a transformer, the stacked core being formed from the grain-oriented electrical steel sheet according to claim 3."
  ],
  "cpc": [
    "H01F 1/16",
    "C21D 8/12",
    "C22C 2202/02",
    "C22C 38/002",
    "C22C 38/02",
    "C22C 38/04",
    "C22C 38/42",
    "C22C 38/44",
    "C22C 38/60",
    "H01F 1/147",
    "H01F 27/245",
    "H01F 41/02",
    "H01F 41/0233",
    "Y02P 10/20"
  ],
  "assignees": [
    "JFE STEEL CORP"
  ],
  "filing_date": "2019-01-31",
  "publication_date": "2022-11-08",
  "grant_date": "2022-11-08",
  "priority_date": "2018-01-31",
  "application_number": "US-201916966268-A",
  "family_id": "67479274",
  "citations": [
    "CN103827326A",
    "EP0892072A1",
    "EP2615189A1",
    "EP2762578A1",
    "EP3205738A1",
    "JP2005240079A",
    "JP2011084778A",
    "JP2012057232A",
    "JP2012126973A",
    "JP2013108149A",
    "JP2017145490A",
    "JP2757724B2",
    "JP5750820B2",
    "JPH01283912A",
    "JPH0572252B2",
    "JPH0672266B2",
    "JPS5484229A",
    "US2016133368A1",
    "US2017263357A1",
    "US2021043358A1",
    "US5296051A",
    "WO2013046716A1"
  ]
}