Jfe Steel Corporation

Yoshiaki Zaizen

Yoshihiko Oda

Tomoyuki Okubo

Yukino Miyamoto

Hiroaki Toda

Masanori Uesaka

Tadashi Nakanishi

Takaaki Tanaka

Kunihiro Senda

Tatsuhiko Hiratani

Souichiro Yoshizaki

Hiroaki Nakajima

Takeshi Omura

Akira Fujita

Kazuhiro Hanazawa

Masaaki Kohno

Tadashi Nakanish

A non-oriented electrical steel sheet having a high magnetic flux density and a low iron loss at a high frequency is produced by subjecting a slab containing, in mass %, C: not more than 0.0050%, Si: 2.8 to 6.5%, Mn: 0.05 to 2.0%, P: not more than 0.10%, S: not more than 0.0050%, Al: 0.3 to 2.0%, N: not more than 0.0050% and Zn: 0.0005 to 0.0050% to a hot rolling, a hot-band annealing, a cold rolling and a finish annealing, a dew point in the hot-band annealing is set to 0 to 70° C. and an atmosphere of the finish annealing has a nitrogen content of not more than 30 vol % and a dew point of not higher than −20° C., and a ratio of the amount of nitrogen present as AlN in an entire sheet thickness to the amount of nitrogen present as AlN in a layer from one-side surface of steel sheet to a depth of 1/20 of sheet thickness is made to not less than 5.0.

Non-oriented electrical steel sheet and method for producing same

Provides is a non-oriented electrical steel sheet suitable for use in a rotor of an IPM motor that has excellent magnetic flux density Band high-frequency iron loss properties, high tensile strength and fatigue strength, and little variation in tensile strength. The non-oriented electrical steel sheet has a predetermined steel sheet chemical composition and a microstructure in which a ratio of non-recrystallized microstructure is 5% or more and 70% or less and the number of inclusion having a diameter of 5 μm or more is not more than 5 counts/mm.

Non-oriented electrical steel sheet and method for manufacturing the same

Provided is a non-oriented electrical steel sheet having excellent adhesion with an insulating coating even if the thickness of the insulating coating is reduced. The non-oriented electrical steel sheet of the present disclosure has an insulating coating on at least one surface of the steel sheet, where the insulating coating has a P-concentrated layer on both a surface side and an interface side with a steel substrate, and a P concentration of the P-concentrated layer is higher than a P concentration in the steel substrate.

Non-oriented electrical steel sheet and method for manufacturing same

In a production of a non-oriented electrical steel sheet comprising subjecting a slab containing a particular composition to a hot rolling, a hot-band annealing, a cold rolling to form a cold-rolled sheet and a finish annealing, a rolling reduction of a final finish rolling pass in the hot rolling is not less than 10%, and a coiling temperature is not higher than 620° C., and a soaking temperature in the finish annealing is 600 to 800° C. to achieve such properties that a recrystallization ratio is less than 100% as an area ratio, a strength C is not less than 2.0 and a strength difference C−D is not more than 2.0, where C is a strength at Φ=0° and φ=0° and D is a strength at Φ=20° and φ=0° in a section of φ=45° of ODF obtained in a central layer of a sheet thickness.

Provided is a laser machining method that causes no degradation in magnetic properties for thin electrical steel sheets. An electrical steel sheet machining method comprises machining an electrical steel sheet to a predetermined shape by melt-cutting the electrical steel sheet using a laser, wherein a scanning rate of the laser in the melt-cutting is 10000 mm/min or more.

Electrical steel sheet machining method, motor, and motor core production method

A method for manufacturing a motor core includes a step of manufacturing a motor core by performing melt-cutting on an electrical steel sheet using heat input from a surface, the electrical steel sheet having an average thermal conductivity in depth positions from the surface to one-third depth of a sheet thickness lower than a thermal conductivity in a middle position in a sheet thickness direction by 30% or greater.

Method for manufacturing motor core

A non-oriented electrical steel sheet having: low high-frequency iron loss and high magnetic flux density; an inner layer and surface layers provided on both sides of the inner layer, the surface layers and the inner layer having specific chemical compositions; the thickness t of 0.01 mm to 0.35 mm; a multilayer ratio of tto t of 0.10 to 0.70, tdenoting a total thickness of the surface layers; a difference between [Si]and [Si]of 1.0 mass % to 4.5 mass % or less, [Si]denoting a Si content in each of the surface layers and [Si]denoting a Si content in the inner layer; and a difference between [Mn]and [Mn]of 0.01 mass % to 0.40 mass %, [Mn]denoting a Mn content at a mid-thickness position t/2 and [Mn]denoting an average Mn content in a region from a surface to a position at a depth of ( 1/10)t.

Non-oriented electrical steel sheet

Disclosed is a non-oriented electrical steel sheet having low iron loss in a frequency range of about 400 Hz. The non-oriented electrical steel sheet comprises an inner layer and surface layers, wherein the inner layer and surface layers have specific chemical compositions, each of the surface layers has an in-plane tensile stress of 5 MPa to 50 MPa, the non-oriented electrical steel sheet has a sheet thickness t of 0.01 mm to 0.35 mm, the surface layers have a total thickness twith a ratio t/t of the total thickness tto the sheet thickness t being 0.10 to 0.70, the non-oriented electrical steel sheet has an average N content [N] in the total sheet thickness of 40 ppm or less, and an iron loss Wand the sheet thickness t satisfy the following formula (1):W≤8+30  (1).

Non-oriented electrical steel sheet and method of producing same

In the production of a non-oriented electrical steel sheet by subjecting a steel slab having a certain component composition to a hot rolling, a hot-band annealing, a cold rolling and a finish annealing, the conditions of the finish annealing are controlled such that a yield stress of the steel sheet after the finish annealing is not less than 480 MPa. Also, when a motor core is produced by using the above steel sheet, there can be provided a non-oriented electrical steel sheet capable of producing a rotor core and a stator core as the same raw material where the stator core is subjected to a stress relief annealing at a soaking temperature of 780 to 950° C. in an atmosphere having a nitrogen content of not more than 30 vol % and a dew point of not higher than −20° C., while a motor core is produced with such a steel sheet.

Method for producing non-oriented electrical steel sheet, method for producing motor core, and motor core

Provided is a method of easily producing a non-oriented electrical steel sheet that contains substantially no Al and contains large amounts of Si and Mn and has low iron loss, comprising hot rolling a slab having a specified chemical composition to obtain a hot-rolled sheet; coiling the hot-rolled sheet; cold rolling the hot-rolled sheet once or twice with intermediate annealing being performed therebetween, to obtain a cold-rolled sheet; and subjecting the cold-rolled sheet to final annealing, wherein the hot-rolled sheet after the hot rolling is cooled at an average cooling rate from 800° C. to 650° C. of 30° C./s or more, and thereafter the coiling is performed at 650° C. or less.

Method of producing a non-oriented electrical steel sheet

Proposed is a non-oriented electrical steel sheet being low in iron loss and excellent in tensile strength and fatigue strength, which has a chemical composition comprising C: not more than 0.005 mass %, Si: 3 to 5 mass %, Mn: not more than 5 mass %, P: not more than 0.1 mass %, S: not more than 0.01 mass %, Al: not more than 3 mass %, N: not more than 0.005 mass %, Zn: 0.0005 mass % to 0.003 mass %, and the remainder being Fe and inevitable impurities, an average crystal grain size being not more than 40 &#x3bc;m, the number of the inclusions having a diameter of not less than 5 &#x3bc;m being not more than 5/mm, a tensile strength being not less than 600 MPa, and the fatigue strength being not less than 450 MPa.

A non-oriented electrical steel sheet with an average magnetostriction &#x3bb;at 400 Hz and 1.0 T of not more than 4.5&#xd7;10, and area ratio of recrystallized grains at a section in rolling direction of steel sheet of 40 to 95% and an average grain size of 10 to 40 &#x3bc;m is obtained by subjecting a steel slab containing, in mass %, C: not more than 0.005%, Si: 2.8 to 6.5%, Mn: 0.05 to 2.0%, Al: not more than 3.0%, P: not more than 0.20%, S: not more than 0.005%, N: not more than 0.005%, Ti: not more than 0.003%, V: not more than 0.005% and Nb: not more than 0.005% and satisfying Si-2Al&#x2014;Mn&#x2265;0 to hot rolling, hot-band annealing, cold rolling and finish annealing under adequate cold rolling and finish annealing conditions, and a motor core is manufactured by such a steel sheet.

Non-oriented electrical steel sheet and method for producing same, and motor core and method for producing same

Provided is a non-oriented electrical steel sheet that contains substantially no Al and contains large amounts of Si and Mn and has low iron loss, comprising a chemical composition containing C: 0.0050% or less, Si: 2.0% or more and 6.0% or less, Mn: 1.0% or more and 3.0% or less, P: 0.20% or less, S: 0.0050% or less, N: 0.0050% or less, Al: 0.0050% or less, and one or more selected from B: 0.0001% or more and 0.0050% or less, Nb: 0.0001% or more and 0.0050% or less, and V: 0.0005% or more and 0.0500% or less, with a balance consisting of Fe and inevitable impurities, wherein a number density of Si&#x2014;Mn nitrides with an average diameter of 50 nm or more and 500 nm or less is 1 or less per &#x3bc;m.

A motor comprising a steel sheet used as a core material of the motor, wherein the steel sheet includes a composition including: by mass %, 0.010% or less of C; 2.0% to 7.0% of Si; 2.0% or less of Al; 0.05% to 1.0% of Mn; 0.005% or less of S; 0.005% or less of N; and balance Fe and inevitable impurities; the steel sheet includes a magnetic flux density changing area where a change &#x394;B in magnetic flux density to a change &#x394;H=50 A/m in a magnetic field, is equal to or higher than 0.50 T; a thickness of the steel sheet is 0.05 mm to 0.20 mm; and an eddy-current loss of the steel sheet, at 1000 Hz&#x2212;1.0 T, is equal to or less than 0.55 of a total iron loss.

Motor

A non-oriented electrical steel sheet with an average magnetostriction &#x3bb;at 400 Hz and 1.0 T of not more than 4.5&#xd7;10, and area ratio of recrystallized grains at a section in rolling direction of steel sheet of 40 to 95% and an average grain size of 10 to 40 &#x3bc;m is obtained by subjecting a steel slab containing, in mass %, C: not more than 0.005%, Si: 2.8 to 6.5%, Mn: 0.05 to 2.0%, Al: not more than 3.0%, P: not more than 0.20%, S: not more than 0.005%, N: not more than 0.005%, Ti: not more than 0.003%, V: not more than 0.005% and Nb: not more than 0.005% and satisfying Si&#x2014;2Al&#x2014;Mn&#x2265;0 to hot rolling, hot-band annealing, cold rolling and finish annealing under adequate cold rolling and finish annealing conditions, and a motor core is manufactured by such a steel sheet.

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Tokyo, Japan

Yoshiaki Zaizen