Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/008—Ferrous alloys, e.g. steel alloys containing tin
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
• • 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
  • H01F1/16—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 in the form of sheets

Definitions

• the present invention relates to a non-oriented electrical steel sheet suitable for a rotor of a high-speed rotary machine.
• a non-oriented electrical steel sheet is used for a rotor of a rotary machine or the like, for example.
• centrifugal force acting on the rotor is in proportion to a rotation radius, and is in proportion to the square of a rotation speed.
• tensile strength of the non-oriented electrical steel sheet for a rotor is preferably high. That is, the non-oriented electrical steel sheet for a rotor preferably has high tension. As described above, high tensile strength (high tension) is required for the non-oriented electrical steel sheet for a rotor.
• a non-oriented electrical steel sheet used for not only a rotor of a rotary machine but also an iron core it is important that its core loss is low.
• the non-oriented electrical steel sheet for a rotor of a high-speed rotary machine it is important that its high-frequency core loss is low.
• a low high-frequency core loss is also required for the non-oriented electrical steel sheet for a rotor. That is, high efficiency when the rotary machine is used at a high frequency is also required.
• the high tension and the low high-frequency core loss are in a relationship such that they are contrary to each other physically, and it is extremely difficult to achieve both of them.
• the present invention has an object to provide a non-oriented electrical steel sheet capable of being manufactured easily and obtaining high tensile strength and a low high-frequency core loss.
• the present inventors have conducted earnest studies on a non-oriented electrical steel sheet from the viewpoint of obtaining favorable mechanical properties while suppressing a core loss low by solid solution strengthening, precipitation strengthening, work strengthening, grain refining strengthening, strengthening by transformation composition, and so on. Further, the present inventors have repeated researches and analyses with regard to what index a high-frequency core loss to be important in an actual high-speed rotary machine becomes, in other words, with regard to at what frequency a core loss is important to be reduced. Further, greater importance is also given to easiness of processes such as cold rolling in a manufacturing process and avoidance of process complication.
• a non-oriented electrical steel sheet according to the present invention contains: C: not less than 0.003 mass% nor more than 0.05 mass%; N: not less than 0.001 mass% nor more than 0.01 mass%; and Si: not less than 2.8 mass% nor more than 3.5 mass%.
• the non-oriented electrical steel sheet further contains at least one kind selected from a group consisting of Ni: 4.0 mass% or less and Mn: 2.0 mass% or less, in a total amount of 0.5 mass% or more, and further contains Ti, a value R Ti being not less than 1 nor more than 10, the value R Ti being expressed by [Ti]/(4x([C]+[N])) when a Ti content is expressed as [Ti] mass%, a C content is expressed as [C] mass%, and an N content is expressed as [N] mass%.
• An Al content is 3.0 mass% or less
• a P content is 0.2 mass% or less
• a balance is composed of Fe and inevitable impurities.
• contents of Si, Mn, Ni, and so on and a value R Ti are appropriate, and thus high tensile strength and a low high-frequency core loss can be obtained. Further, the contents of Si and so on are appropriate, and thus processes in a manufacturing process are easy to be performed, and addition of complex processes based on embrittlement and the like can also be avoided.
• Si has an effect of reducing a core loss such as a high-frequency core loss by increasing electrical resistance of the non-oriented electrical steel sheet to thereby reduce an eddy current loss. Further, Si has an effect of increasing tension of the non-oriented electrical steel sheet by solid solution strengthening. When a Si content is less than 2.8 mass%, these effects is insufficient. On the other hand, when the Si content exceeds 3.5 mass%, a reduction in a magnetic flux density, embrittlement, difficulty in performing processes of cold rolling and the like, and an increase in a material cost are caused. Thus, the Si content is set to not less than 2.8 mass% nor more than 3.5 mass%.
• Al similarly to Si, has an effect of reducing a core loss such as a high-frequency core loss by increasing the electrical resistance of the non-oriented electrical steel sheet to thereby reduce an eddy current loss.
• Al may also be contained as an aim to further reduce a high-frequency core loss.
• an Al content exceeds 3.0 mass%, a reduction in a magnetic flux density, embrittlement, difficulty in performing processes of cold rolling and the like, and an increase in a material cost are caused.
• an upper limit of the Al content is set to 3.0 mass%.
• the Al content is less than 0.1 mass%, fine precipitation of A1N is remarkably exhibited to increase a core loss, and thus the Al content is preferably 0.1 mass% or more.
• Ni and Mn contribute to an improvement in tension of the non-oriented electrical steel sheet. That is, Ni has an effect of increasing the tension by solid solution strengthening, and Mn has an effect of increasing the tension by solid solution strengthening and grain refining strengthening. Further, Ni also has an effect of reducing a core loss such as a high-frequency core loss by increasing the electrical resistance of the non-oriented electrical steel sheet to thereby reduce an eddy current loss. Further, Ni also contributes to an improvement in a magnetic flux density in accordance with an increase in a saturated magnetic moment of the non-oriented electrical steel sheet. Mn has an effect of reducing a core loss such as a high-frequency core loss by increasing the electrical resistance of the non-oriented electrical steel sheet to thereby reduce an eddy current loss.
• Ni content and Mn content are less than 0.5 mass%, these effects are insufficient, resulting that tensile strength of 900 MPa or more cannot be obtained.
• Ni content exceeds 4.0 mass%, a reduction in a magnetic flux density ascribable to the reduction in a saturated magnetic moment occurs.
• Mn content exceeds 2.0 mass%, a magnetic flux density is reduced and further a material cost is increased.
• Ni of 4.0 mass% or less and/or Mn of 2.0 mass% or less are/is contained in a total amount of 0.5 mass% or more.
• P has an effect of greatly increasing the tension of the non-oriented electrical steel sheet.
• P may also be contained as an aim to further improve the tension.
• 0.001 mass% or more of P is preferably contained.
• P content exceeds 0.2 mass%, P segregates in crystal grain boundaries in a manufacturing process to embrittle a hot-rolled steel sheet, resulting that cold rolling thereafter becomes extremely difficult to be performed.
• an upper limit of the P content is set to 0.2 mass%.
• Ti has an effect of reacting with C and N to form a fine precipitate containing Ti carbonitride and increasing the tension of the non-oriented electrical steel sheet by precipitation strengthening and grain refining strengthening. Further,' Ti being solid-dissolved in the non-oriented electrical steel sheet has an effect of orienting crystal orientations of a surface of the non-oriented electrical steel sheet in ⁇ 111 ⁇ when cold rolling, finish annealing, and the like, and increasing the tension of the non-oriented electrical steel sheet. In order to exhibit these effects sufficiently, it is important that appropriate amounts of both Ti to be precipitated as Ti carbonitride and Ti being solid-dissolved in the non-oriented electrical steel sheet are contained.
• a Ti content is expressed as [Ti] mass%
• a C content is expressed as [C] mass%
• an N content is expressed as [N] mass%
• the value R Ti is set to 1 or more. In the case of the value R Ti being 1, all Ti is bonded to C and/or N theoretically, but practically, part of Ti is not bonded to either C or N to be contained in the non-oriented electrical steel sheet as solid solution Ti. Note that the value R Ti is preferably 2 or more, and more preferably 3 or more.
• the value R Ti exceeds 10, recrystallization is unlikely to occur and further embrittlement is likely to occur. Further, there is sometimes a case that in accordance with an increase in the solid solution Ti, the orientation to ⁇ 111 ⁇ is too intensified to increase a core loss.
• the value R Ti is set to 10 or less. Incidentally, the value R Ti is preferably 9 or less, and more preferably 7 or less.
• the value R Ti falls within a range as above, it is set in a manner that the C content is not less than 0.003 mass% nor more than 0.05 mass% and the N content is not less than 0.001 mass% nor more than 0.01 mass%.
• the C content exceeds 0.05 mass%, or the N content exceeds 0.01 mass%, core loss properties are remarkably reduced due to magnetic aging or the like.
• the Ti content is preferably not less than 0.1 mass% nor more than 0.3 mass%, and an upper limit of the Ti content is more preferably 0.25 mass%.
• the components of the non-oriented electrical steel sheet except the above-described components are Fe and inevitable impurities, for example.
• B may also be contained.
• a B content is preferably 0.001 mass% or more.
• the B content exceeds 0.007 mass%, a reduction in a magnetic flux density, embrittlement at the time of hot rolling, and the like are caused.
• the B content is preferably 0.007 mass% or less.
• Cu not less than 0.02 mass% nor more than 1.0 mass%
• Sn not less than 0.02 mass% nor more than 0.5 mass%
• Sb not less than 0.02 mass% nor more than 0.5 mass%
• Cr not less than 0.02 mass% nor more than 3.0 mass%
• rare earth metal REM: rare earth metal
• the tensile strength of the non-oriented electrical steel sheet composed of these components becomes, for example, 900 MPa or more. Therefore, a rotor of a high-speed rotary machine manufactured by using the above non-oriented electrical steel sheet can achieve sufficient high-speed rotation.
• a high-frequency core loss W 10/1000 of the non-oriented electrical steel sheet composed of these components becomes, for example, 100 W/kg or less. Therefore, a rotor of a high-speed rotary machine manufactured by using the above non-oriented electrical steel sheet can contribute to high-efficiency and miniaturization of the rotary machine. That is, energy loss caused by converting from electric energy into mechanical energy and heat generation incidental to the conversion can be suppressed. Then, in order to reduce an eddy current loss to thereby make the high-frequency core loss W 10/1000 become 100 W/kg or less, a thickness of the non-oriented electrical steel sheet is preferably 0.30 mm or less.
• the present inventors confirmed these effects by the following experiments.
• a slab containing C: 0.017 mass%, Si: 3.12 mass%, Al: 0.65 mass%, Ni: 2.54 mass%, P: 0.02 mass%, N: 0.003 mass%, and Ti: 0.18 mass% was hot-rolled, and a hot-rolled steel sheet was obtained.
• the value R Ti of the above hot-rolled steel sheet is 2.3.
• the hot-rolled steel sheet was cold-rolled to have four types of thicknesses shown in Table 1, and a cold-rolled steel sheet was obtained. Thereafter, continuous finish annealing at 780°C for 20 seconds was applied to the cold-rolled steel sheet, and a non-oriented electrical steel sheet was obtained.
• the thickness of the non-oriented electrical steel sheet is preferably 0.30 mm or less.
• the non-oriented electrical steel sheet according to the present invention can be manufactured in the following manner, for example. First, a slab having the above-described composition is melted, and the above slab is heated and hot rolled to obtain a hot-rolled steel sheet. Next, the above hot-rolled steel sheet is cold rolled to obtain a cold-rolled steel sheet. Thereafter, finish annealing is performed. Incidentally, in order to avoid a reduction in strength and embrittlement accompanying growth of crystal grains, hot-rolled sheet annealing is preferably not performed, and intermediate annealing during cold rolling is also preferably not performed.
• the hot-rolled steel sheet having the above-described composition As long as the hot-rolled steel sheet having the above-described composition is used, the effects of the improvement in tension and the reduction in a high-frequency core loss can be obtained without performing hot-rolled sheet annealing and intermediate annealing. Further, hot-rolled sheet annealing is omitted, thereby also enabling bending workability to be improved. That is, since the non-oriented electrical steel sheet according to the present invention has the above-described composition, the improvement in tension and the reduction in a high-frequency core loss can be achieved by the relatively simple processes.
• Epstein samples and tensile test pieces were cut out from the non-oriented electrical steel sheets.
• magnetic properties were measured by using the Epstein samples, and mechanical properties were measured by using the tensile test pieces. Results thereof are shown in Table 3.
• Epstein samples and tensile test pieces were cut out from the non-oriented electrical steel sheets.
• magnetic properties were measured by using the Epstein samples, and mechanical properties were measured by using the tensile test pieces. Results thereof are shown in Table 5.
• the present invention can be utilized in, for example, the electrical steel sheet manufacturing industry and the electrical steel sheet utilizing industry.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
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• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Dispersion Chemistry (AREA)
• Power Engineering (AREA)
• Soft Magnetic Materials (AREA)
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• 2010
  • 2010-01-19 PL PL10733454T patent/PL2390376T3/pl unknown
  • 2010-01-19 EP EP10733454.2A patent/EP2390376B1/fr active Active
  • 2010-01-19 WO PCT/JP2010/050520 patent/WO2010084847A1/fr not_active Ceased
  • 2010-01-19 CN CN2010800053348A patent/CN102292462A/zh active Pending
  • 2010-01-19 JP JP2010522041A patent/JP4681687B2/ja active Active
  • 2010-01-19 KR KR1020117017427A patent/KR101325369B1/ko active Active
  • 2010-01-19 US US13/132,270 patent/US20110229362A1/en not_active Abandoned
  • 2010-01-19 BR BRPI1007193-8A patent/BRPI1007193B1/pt active IP Right Grant
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