Non-directional electromagnetic steel plates, rotor cores, stator cores, and motors

Abstract

A non-directional electromagnetic steel sheet is provided that can achieve high strength, excellent magnetic flux density, and excellent iron loss. According to the non-directional electromagnetic steel sheet disclosed herein, it has the chemical composition described in the specification, the plate thickness t is 0.30 mm or less, F1 as defined by formula (1) is 10.0 or more, F2 as defined by formula (2) is 8.5 or less, F3 as defined by formula (3) is iron loss W5 / 1000 or less and the iron loss W5 / 1000 is the iron loss at a frequency of 1000 Hz and a magnetic flux density of 0.5 T, and F4 as defined by formula (4) is iron loss W10 / 400 or more and the iron loss W10 / 400 is the iron loss of the non-directional electromagnetic steel sheet at a frequency of 400 Hz and a magnetic flux density of 1.0 T after heat treatment at 800°C for 1 hour. F1=4Si+3Al+2Mn (1)F2=2Si+3Al+Mn (2)F3=45-12Si-5Al-2Mn+1000×t / (5+6Si+5Al+3Mn) (3)F4=4+800×t / (5+6Si+5Al+3Mn) (4)

Description

Technical Field

[0001] Invention Field This disclosure relates to non-directional electromagnetic steel sheets, rotor cores and stator cores manufactured from non-directional electromagnetic steel sheets, and motors having rotor cores and stator cores. Prior Technology

[0002] Background of the Invention Non-directional electromagnetic steel sheets are widely used as motor cores. A motor core consists of a rotor and a stator. The rotor and stator cores require different characteristics.

[0003] Specifically, the rotor core requires not only low iron losses to improve motor efficiency, but also high strength for reasons explained later. In motors used in electric and hybrid vehicles, the design increases motor output by increasing the motor's rotational speed. This increased output leads to a greater centrifugal force applied to the rotor core during operation. Therefore, the rotor core requires both low iron losses and high strength.

[0004] On the other hand, the stator core does not require the same high strength as the rotor core; instead, it requires excellent iron loss in order to improve motor efficiency.

[0005] As mentioned above, the required strength and iron loss grades for the rotor core and stator core are different. Furthermore, both the rotor and stator cores are manufactured using the same non-directional electromagnetic steel sheet as the raw material. Specifically, the rotor and stator cores are punched and machined from the same non-directional electromagnetic steel sheet.

[0006] The technology disclosed in Japanese Patent Application Publication No. 2008-050686 (Patent Document 1) is used to obtain a high-strength rotor core and a stator core with excellent iron loss from the same non-directional electromagnetic steel sheet.

[0007] Patent Document 1 describes the manufacture of a non-directional electromagnetic steel sheet having a high-alloy chemical composition, which, by mass percent, contains: C: 0.0050% or less, Si: 2.0% or more and 4.0% or less, Mn: 0.05% or more and 2.0% or less, Al: 3.0% or less, Ti: 0.0030% or less, S: 0.0030% or less, N: 0.0030% or less, V: 0.0050% or less, Nb: 0.0050% or less, Zr: 0.0050% or less, As: 0.0050% or less, with the remainder consisting of Fe and unavoidable impurities; it is a thin sheet with a thickness of 0.15 to 0.35 mm. Then, a rotor and a stator are punched from the same non-directional electromagnetic steel sheet. Only the punched stator is heat-treated, while the punched rotor is not heat-treated.

[0008] Patent Document 1 describes a method to achieve excellent iron loss and the required high strength for the rotor core by high alloying of non-directional electromagnetic steel sheets. Then, a stator core is manufactured by punching the high alloy and thin sheet of non-directional electromagnetic steel. The stator core is then heat-treated to further reduce its iron loss. This technique attempts to achieve both high strength for the rotor core and low iron loss for the stator using the same non-directional electromagnetic steel sheet.

[0009] [Previous Technical Documents] [Patent Literature] [Patent Document 1] Japanese Patent Application Publication No. 2008-050686 Summary of the Invention

[0010] Invention Summary The problem that the invention aims to solve As mentioned above, motors strive for high strength in the rotor core and low iron loss in the stator core. Motors also aim to increase torque. Magnetic flux density is the driving force behind torque. Therefore, non-directional electromagnetic steel sheets, as the material, also require excellent magnetic flux density.

[0011] In the aforementioned patent document 1, a thin sheet of non-directional electromagnetic steel is high-alloyed. This ensures strength while reducing iron loss. However, with high-alloy and thin sheets of non-directional electromagnetic steel, sufficient magnetic flux density may not always be achieved.

[0012] The purpose of this invention is to provide a non-directional electromagnetic steel plate, rotor core, stator core, and motor that can achieve high strength, excellent magnetic flux density, and excellent iron loss.

[0013] The means to solve the problem According to the non-directional electromagnetic steel sheet disclosed herein, its chemical composition, by mass%, contains: Si: 2.0~4.0%, Mn: 0.1~1.5%, P: less than 0.15%, S: less than 0.0030%, Al: 0.1~2.0%, C: less than 0.0050%, N: less than 0.0050%, O: less than 0.0500%, Cr: 0~0.50%, Ti: 0~0.0030%, Mo: 0~0.100%, Ni: 0~0.50%, Cu: 0~0.50%, Sn: 0~0.100%, Sb: 0~0.100%, Ca: 0 The composition is as follows: ~0.0050%, Mg: 0~0.0030%, rare earth elements: 0~0.0100%, B: 0~0.0030%, Zn: 0~0.0030%, Ge: 0~0.0030%, As: 0~0.0100%, Co: 0~0.0500%, V: 0~0.0030%, Se: 0~0.0030%, Zr: 0~0.0030%, Nb: 0~0.0030%, Pb: 0~0.0030%, and Ga: 0~0.0030%, with the remainder consisting of Fe and impurities; the plate thickness t is less than 0.30 mm. F1 as defined in formula (1) is 10.0 or more, and F2 as defined in formula (2) is 8.5 or less. Furthermore, F3 as defined in equation (3) is an iron loss W5 / 1000 or less, and the iron loss W5 / 1000 is the iron loss at a frequency of 1000Hz and a magnetic flux density of 0.5T. F4 as defined in equation (4) is an iron loss W10 / 400 or more, and the iron loss W10 / 400 is the iron loss at a frequency of 400Hz and a magnetic flux density of 1.0T after the non-directional electromagnetic steel plate has been heat-treated at 800℃ for 1 hour. F1 = 4Si + 3Al + 2Mn (1) F2=2Si+3Al+Mn (2) F3=45-12Si-5Al-2Mn+1000×t / (5+6Si+5Al+3Mn) (3) F4=4+800×t / (5+6Si+5Al+3Mn) (4) Here, the element symbols in equations (1) to (4) are the content of the corresponding element in terms of mass % and t is the plate thickness in terms of mm.

[0014] According to the rotor core disclosed herein, it comprises: several stacked rotor core materials. The rotor core materials are plate-shaped. Regarding the rotor core materials, their chemical composition, in mass percent, contains: Si: 2.0~4.0%, Mn: 0.1~1.5%, P: less than 0.15%, S: less than 0.0030%, Al: 0.1~2.0%, C: less than 0.0050%, N: less than 0.0050%, O: less than 0.0500%, Cr: 0~0.50%, Ti: 0~0.0030%, Mo: 0~0.100%, Ni: 0~0.50%, Cu: 0~0.50%, Sn: 0~0.100%, Sb: 0~0.100%, Ca: 0~0. 0.050%, Mg: 0~0.0030%, rare earth elements: 0~0.0100%, B: 0~0.0030%, Zn: 0~0.0030%, Ge: 0~0.0030%, As: 0~0.0100%, Co: 0~0.0500%, V: 0~0.0030%, Se: 0~0.0030%, Zr: 0~0.0030%, Nb: 0~0.0030%, Pb: 0~0.0030%, and Ga: 0~0.0030%, with the remainder consisting of Fe and impurities; its plate thickness t is less than 0.30 mm. F1 as defined in formula (1) is 10.0 or more, and F2 as defined in formula (2) is 8.5 or less. Furthermore, F3 as defined in equation (3) is an iron loss of less than W5 / 1000 and the iron loss W5 / 1000 is the iron loss at a frequency of 1000Hz and a magnetic flux density of 0.5T. F4 as defined in equation (4) is an iron loss of more than W10 / 400 and the iron loss W10 / 400 is the iron loss at a frequency of 400Hz and a magnetic flux density of 1.0T after the rotor core material has been heat-treated at 800℃ for 1 hour. F1 = 4Si + 3Al + 2Mn (1) F2=2Si+3Al+Mn (2) F3=45-12Si-5Al-2Mn+1000×t / (5+6Si+5Al+3Mn) (3) F4=4+800×t / (5+6Si+5Al+3Mn) (4) Here, the element symbols in equations (1) to (4) are the content of the corresponding element in terms of mass % and t is the plate thickness in terms of mm.

[0015] According to the stator core disclosed herein, it comprises: a plurality of stator core materials that are stacked on top of each other. The stator core materials are in the shape of annular plates; the stator core materials include: a plurality of teeth, which are arranged with gaps in the circumferential direction of the stator core materials and extend in the radial direction of the stator core materials. Regarding the stator core material, its chemical composition, by mass%, contains: Si: 2.0~4.0%, Mn: 0.1~1.5%, P: less than 0.15%, S: less than 0.0030%, Al: 0.1~2.0%, C: less than 0.0050%, N: less than 0.0050%, O: less than 0.0500%, Cr: 0~0.50%, Ti: 0~0.0030%, Mo: 0~0.100%, Ni: 0~0.50%, Cu: 0~0.50%, Sn: 0~0.100%, Sb: 0~0.100%, Ca: 0~0. 0.050%, Mg: 0~0.0030%, rare earth elements: 0~0.0100%, B: 0~0.0030%, Zn: 0~0.0030%, Ge: 0~0.0030%, As: 0~0.0100%, Co: 0~0.0500%, V: 0~0.0030%, Se: 0~0.0030%, Zr: 0~0.0030%, Nb: 0~0.0030%, Pb: 0~0.0030%, and Ga: 0~0.0030%, with the remainder consisting of Fe and impurities; its plate thickness t is less than 0.30 mm. F1 as defined in formula (1) is 10.0 or more, and F2 as defined in formula (2) is 8.5 or less. Furthermore, F4 as defined in equation (4) is an iron loss W10 / 400 or higher, and the iron loss W10 / 400 is the iron loss at a frequency of 400Hz and a magnetic flux density of 1.0T. F1 = 4Si + 3Al + 2Mn (1) F2=2Si+3Al+Mn (2) F4=4+800×t / (5+6Si+5Al+3Mn) (4) Here, the element symbols in equations (1), (2) and (4) are the content of the corresponding element in terms of mass % and t is the plate thickness in terms of mm.

[0016] The motor disclosed herein comprises: the aforementioned rotor core and the aforementioned stator core.

[0017] Invention Effects The non-directional electromagnetic steel sheet disclosed herein achieves high strength and excellent magnetic flux density, as well as excellent iron loss. The rotor core disclosed herein achieves high strength and excellent magnetic flux density. The stator core disclosed herein achieves excellent magnetic flux density and excellent iron loss. Simple Explanation of the Diagram

[0018] Figure 1A is a plan view showing an example of the rotor core of this embodiment. Figure 1B is a plan view showing an example where the rotor core of this embodiment differs from that in Figure 1A. Figure 1C is a plan view showing an example of a rotor core in this embodiment that differs from those in Figures 1A and 1B. Figure 2A is a cross-sectional view of line segment IIA-IIA of the convergence region in Figure 1A. Figure 2B is a cross-sectional view of line segment IIB-IIB at the convergence point in Figure 1A. Figure 3 is a plan view of the stator core of this embodiment. Implementation

[0019] Embodiments of the present invention Forms used to implement inventions The inventors of this case have reviewed a non-directional electromagnetic steel sheet that can achieve high strength, excellent magnetic flux density, and excellent iron loss. As mentioned above, in order to obtain excellent magnetic flux density, it is advisable to avoid increasing the content of alloying elements. Therefore, the inventors of this case, for the first time, have reviewed a non-directional electromagnetic steel sheet that can achieve high strength, excellent magnetic flux density, and excellent iron loss after heat treatment from the viewpoint of chemical composition. The results showed that the chemical composition of the non-directional electromagnetic steel sheet, by mass%, contained: Si: 2.0~4.0%, Mn: 0.1~1.5%, P: less than 0.15%, S: less than 0.0030%, Al: 0.1~2.0%, C: less than 0.0050%, N: less than 0.0050%, O: less than 0.0500%, Cr: 0~0.50%, Ti: 0~0.0030%, Mo: 0~0.100%, Ni: 0~0.50%, Cu: 0~0.50%, Sn: 0~0.100%, Sb: 0~0.100%, Ca: 0~0.0050%. Mg: 0~0.0030%, rare earth elements: 0~0.0100%, B: 0~0.0030%, Zn: 0~0.0030%, Ge: 0~0.0030%, As: 0~0.0100%, Co: 0~0.0500%, V: 0~0.0030%, Se: 0~0.0030%, Zr: 0~0.0030%, Nb: 0~0.0030%, Pb: 0~0.0030%, and Ga: 0~0.0030%, with the remainder consisting of Fe and impurities. This composition makes it possible to obtain high strength, excellent magnetic flux density, and excellent iron loss after heat treatment.

[0020] The inventors further examined methods for obtaining high strength, excellent magnetic flux density, and excellent iron loss for non-directional electromagnetic steel sheets that meet the above chemical composition.

[0021] In the above chemical composition, Si, Al, and Mn increase the resistivity of the steel sheet and reduce iron loss. On the other hand, Si, Al, and Mn reduce the magnetic flux density. Therefore, the relationship between Si content, Al content, Mn content, iron loss, and magnetic flux density was further investigated for steel sheets that meet the above chemical composition. As a result, the inventors of this case found that in non-directional electromagnetic steel sheets that meet the above chemical composition, if F1 as defined by equation (1) is 10.0 or more and F2 as defined by equation (2) is 8.5 or less, it is possible to have both excellent iron loss and excellent magnetic flux density. F1 = 4Si + 3Al + 2Mn (1) F2=2Si+3Al+Mn (2) Here, the element symbols in equations (1) and (2) represent the content of the corresponding element expressed as a percentage of mass.

[0022] The inventors of this case further examined methods to improve strength in addition to excellent iron loss and excellent magnetic flux density for non-directional electromagnetic steel sheets that meet the above chemical composition and have an F1 of 10.0 or higher and an F2 of 8.5 or lower. In the above chemical composition, it is not desirable to achieve high strength through alloying elements. Therefore, as a high-strength improvement method different from high alloying, the focus is on the strain introduced into the steel sheet and the strain distribution within the steel sheet. If the strain introduced into the steel sheet and the strain distribution are appropriate, the strength of the steel sheet can be improved without relying on alloying elements. On the other hand, the strain introduced into the steel sheet will degrade iron loss. However, if the strain can be removed through heat treatment and the strain can be used as a driving force to reduce the grain boundary area in the steel sheet, the iron loss can be further reduced.

[0023] It is extremely difficult to quantitatively demonstrate the strain and strain distribution in steel plates. Therefore, the inventors of this case reviewed the indicators related to strain and strain distribution. It was found that if F3 as defined by equation (3) is less than or equal to the iron loss W5 / 1000 and the iron loss W5 / 1000 is the iron loss at a frequency of 1000Hz and a magnetic flux density of 0.5T, and F4 as defined by equation (4) is greater than or equal to the iron loss W10 / 400 and the iron loss W10 / 400 is the iron loss at a frequency of 400Hz and a magnetic flux density of 1.0T after the non-directional electromagnetic steel plate has undergone stress-relaxation annealing, then high strength and excellent magnetic flux density can be obtained, and excellent iron loss can also be obtained after heat treatment. F3=45-12Si-5Al-2Mn+1000×t / (5+6Si+5Al+3Mn) (3) F4=4+800×t / (5+6Si+5Al+3Mn) (4) Here, the element symbols in equations (3) and (4) are the content of the corresponding element in terms of mass % and t is the plate thickness in terms of mm.

[0024] The non-directional electromagnetic steel plate, rotor core, stator core, and motor of this embodiment, based on the above insights, have the following configuration.

[0025] In the first type of non-directional electromagnetic steel sheet, its chemical composition (by mass%) is as follows: Si: 2.0~4.0%, Mn: 0.1~1.5%, P: less than 0.15%, S: less than 0.0030%, Al: 0.1~2.0%, C: less than 0.0050%, N: less than 0.0050%, O: less than 0.0500%, Cr: 0~0.50%, Ti: 0~0.0030%, Mo: 0~0.100%, Ni: 0~0.50%, Cu: 0~0.50%, Sn: 0~0.100%, Sb: 0~0.100%, Ca: 0~ 0.0050%, Mg: 0~0.0030%, rare earth elements: 0~0.0100%, B: 0~0.0030%, Zn: 0~0.0030%, Ge: 0~0.0030%, As: 0~0.0100%, Co: 0~0.0500%, V: 0~0.0030%, Se: 0~0.0030%, Zr: 0~0.0030%, Nb: 0~0.0030%, Pb: 0~0.0030%, Ga: 0~0.0030%, and the remainder is composed of Fe and impurities; its plate thickness t is less than 0.30 mm. F1 as defined in formula (1) is 10.0 or more, and F2 as defined in formula (2) is 8.5 or less. Furthermore, F3 as defined in equation (3) is an iron loss W5 / 1000 or less, and the iron loss W5 / 1000 is the iron loss at a frequency of 1000Hz and a magnetic flux density of 0.5T. F4 as defined in equation (4) is an iron loss W10 / 400 or more, and the iron loss W10 / 400 is the iron loss at a frequency of 400Hz and a magnetic flux density of 1.0T after the non-directional electromagnetic steel plate has been heat-treated at 800℃ for 1 hour. F1 = 4Si + 3Al + 2Mn (1) F2=2Si+3Al+Mn (2) F3=45-12Si-5Al-2Mn+1000×t / (5+6Si+5Al+3Mn) (3) F4=4+800×t / (5+6Si+5Al+3Mn) (4) Here, the element symbols in equations (1) to (4) are the content of the corresponding element in terms of mass % and t is the plate thickness in terms of mm.

[0026] Regarding the second type of non-directional electromagnetic steel sheet, it is the first type of non-directional electromagnetic steel sheet, and its chemical composition contains one or more elements selected from the following groups: Cr: 0.01~0.50%, Ti: 0.0001~0.0030%, Mo: 0.001~0.100%, Ni: 0.01~0.50%, Cu: 0.01~0.50%, Sn: 0.001~0.100%, Sb: 0.001~0.100%, Ca: 0.0001~0.0050%, Mg: 0.0001~0.0030%, rare earth elements: 0. 0001~0.0100%, B:0.0001~0.0030%, Zn:0.0001~0.0030%, Ge:0.0001~0.0030%, As:0.0001~0.0100%, Co:0.0001~0.0500%, V:0 .0001~0.0030%, Se: 0.0001~0.0030%, Zr: 0.0001~0.0030%, Nb: 0.0001~0.0030%, Pb: 0.0001~0.0030%, and Ga: 0.0001~0.0030%.

[0027] Regarding the third type of non-directional electromagnetic steel sheet, it is the first or second type of non-directional electromagnetic steel sheet, and its yield stress is above 450MPa and its tensile strength at break is above 20%.

[0028] Regarding the fourth type of non-directional electromagnetic steel sheet, which is any one of the first to third types of non-directional electromagnetic steel sheet, and with the rolling direction as the reference 0°, the magnetic flux density B50 in each angular direction with a spacing of 22.5° is defined as: B50(0°), B50(22.5°), B50(45°), B50(67.5°) and B50(90°). At this time, the average magnetic flux density B50ave defined by formula (5) is 1.65T or more. B50ave=(B50(0°)+2×B50(22.5°)+2×B50(45°)+2×B50(67.5°)+B50(90°)) / 8 (5)

[0029] Regarding the fifth type of non-directional electromagnetic steel sheet, which is any one of the first to fourth types of non-directional electromagnetic steel sheet, and after the non-directional electromagnetic steel sheet is heat-treated at 800°C for 1 hour, the iron loss W10 / 400 is F4 or less. Further, with the rolling direction as the reference 0°, the magnetic flux density B1 in each angular direction with a 22.5° interval is defined as: B1(0°), B1(22.5°), B1(45°), B1(67.5°) and B1(90°). At this time, the average magnetic flux density B1ave defined by formula (6) is 0.70T or more. Furthermore, with the direction of the maximum value of magnetic flux density B500 as the reference 0°, the magnetic flux density B500 in each angular direction at a 22.5° interval is defined as: B500(0°), B500(22.5°), B500(45°), B500(67.5°) and B500(90°). At this time, the average magnetic flux density B500ave defined by equation (7) is 1.98T or more. B1ave=(B1(0°)+2×B1(22.5°)+2×B1(45°)+2×B1(67.5°)+B1(90°)) / 8 (6) B500ave=(B500(0°)+2×B500(22.5°)+2×B500(45°)+2×B500(67.5°)+B500(90°)) / 8 (7)

[0030] Regarding the sixth type of non-directional electromagnetic steel sheet, it is any one of the first to fifth types of non-directional electromagnetic steel sheet, and its thermal conductivity at 20°C is 20 W / mK or higher, and its thermal conductivity at 150°C is 23 W / mK or higher.

[0031] The first type of rotor core comprises: several laminated rotor core materials. The rotor core materials are plate-shaped. The chemical composition of the rotor core materials, in mass percent, is as follows: Si: 2.0~4.0%, Mn: 0.1~1.5%, P: less than 0.15%, S: less than 0.0030%, Al: 0.1~2.0%, C: less than 0.0050%, N: less than 0.0050%, O: less than 0.0500%, Cr: 0~0.50%, Ti: 0~0.0030%, Mo: 0~0.100%, Ni: 0~0.50%, Cu: 0~0.50%, Sn: 0~0.100%, Sb: 0~0.100%, Ca: 0~0.0 0.50%, Mg: 0~0.0030%, rare earth elements: 0~0.0100%, B: 0~0.0030%, Zn: 0~0.0030%, Ge: 0~0.0030%, As: 0~0.0100%, Co: 0~0.0500%, V: 0~0.0030%, Se: 0~0.0030%, Zr: 0~0.0030%, Nb: 0~0.0030%, Pb: 0~0.0030%, Ga: 0~0.0030%, and the remainder is composed of Fe and impurities; its plate thickness t is less than 0.30 mm. F1 as defined in formula (1) is 10.0 or more, and F2 as defined in formula (2) is 8.5 or less. Furthermore, F3 as defined in equation (3) is an iron loss of less than W5 / 1000 and the iron loss W5 / 1000 is the iron loss at a frequency of 1000Hz and a magnetic flux density of 0.5T. F4 as defined in equation (4) is an iron loss of more than W10 / 400 and the iron loss W10 / 400 is the iron loss at a frequency of 400Hz and a magnetic flux density of 1.0T after the rotor core material has been heat-treated at 800℃ for 1 hour. F1 = 4Si + 3Al + 2Mn (1) F2=2Si+3Al+Mn (2) F3=45-12Si-5Al-2Mn+1000×t / (5+6Si+5Al+3Mn) (3) F4=4+800×t / (5+6Si+5Al+3Mn) (4) Here, the element symbols in equations (1) to (4) are the content of the corresponding element in terms of mass % and t is the thickness of the plate mentioned above in mm.

[0032] Regarding the rotor core of the second type, it is the rotor core of the first type, and its rotor core material further includes: a convergent portion and a flat portion having a flat area. The convergent portion includes an inclined portion formed relative to the flat portion. The thickness of the inclined portion is less than 85% of the thickness of the flat portion.

[0033] Regarding the rotor core of the third type, it is the rotor core of the second type, and in the cross section including the central axis of the rotor core material, the Vickers hardness H14 at the center of the plate thickness in the flat part is 180HV or higher, and the Vickers hardness H121 at the center of the plate thickness in the inclined part is H14+40HV or higher.

[0034] The first type of stator core comprises: several stator core materials stacked on top of each other. The stator core materials are in the shape of a circular ring plate. The stator core materials include: several teeth, which are arranged with gaps in the circumferential direction of the stator core materials and extend in the radial direction of the stator core materials. Regarding the stator core material, its chemical composition, by mass%, contains: Si: 2.0~4.0%, Mn: 0.1~1.5%, P: less than 0.15%, S: less than 0.0030%, Al: 0.1~2.0%, C: less than 0.0050%, N: less than 0.0050%, O: less than 0.0500%, Cr: 0~0.50%, Ti: 0~0.0030%, Mo: 0~0.100%, Ni: 0~0.50%, Cu: 0~0.50%, Sn: 0~0.100%, Sb: 0~0.100%, Ca: 0~0. 0.050%, Mg: 0~0.0030%, rare earth elements: 0~0.0100%, B: 0~0.0030%, Zn: 0~0.0030%, Ge: 0~0.0030%, As: 0~0.0100%, Co: 0~0.0500%, V: 0~0.0030%, Se: 0~0.0030%, Zr: 0~0.0030%, Nb: 0~0.0030%, Pb: 0~0.0030%, and Ga: 0~0.0030%, with the remainder consisting of Fe and impurities; its plate thickness t is less than 0.30 mm. F1 as defined in formula (1) is 10.0 or more, and F2 as defined in formula (2) is 8.5 or less. Furthermore, F4 as defined in equation (4) is an iron loss W10 / 400 or higher, and the iron loss W10 / 400 is the iron loss at a frequency of 400Hz and a magnetic flux density of 1.0T. F1 = 4Si + 3Al + 2Mn (1) F2=2Si+3Al+Mn (2) F4=4+800×t / (5+6Si+5Al+3Mn) (4) Here, the element symbols in equations (1), (2) and (4) are the content of the corresponding element in terms of mass % and t is the plate thickness in terms of mm.

[0035] Regarding the stator core of the second type, it is the stator core of the first type, and its stator core material further includes: a convergent portion and a flat portion having a flat area. The convergent portion includes an inclined portion formed relative to the flat portion. The thickness of the inclined portion is less than 85% of the thickness of the flat portion.

[0036] Regarding the third type of stator core, it is the second type of stator core, and in the cross section including the central axis of the stator core material, the Vickers hardness H24 at the center of the plate thickness in the flat part is 175HV or higher, and the Vickers hardness H221 at the center of the plate thickness in the inclined part is the aforementioned Vickers hardness H24±10HV or lower.

[0037] The motor of the first type has: a rotor core of any one of the first to third types, and a stator core of any one of the first to third types.

[0038] The following describes the non-directional electromagnetic steel plate, rotor core, stator core, and motor of this embodiment. Additionally, the percentage of element content (%) generally refers to mass percentage unless otherwise specified.

[0039] [Features of the non-directional electromagnetic steel sheet in this embodiment] The non-directional electromagnetic steel plate of this embodiment satisfies the following characteristics 1 to 5. (Feature 1) The chemical composition, by mass%, contains: Si: 2.0~4.0%, Mn: 0.1~1.5%, P: less than 0.15%, S: less than 0.0030%, Al: 0.1~2.0%, C: less than 0.0050%, N: less than 0.0050%, O: less than 0.0500%, Cr: 0~0.50%, Ti: 0~0.0030%, Mo: 0~0.100%, Ni: 0~0.50%, Cu: 0~0.50%, Sn: 0~0.100%, Sb: 0~0.100%, Ca: 0~0. 0.0050%, Mg: 0~0.0030%, rare earth elements: 0~0.0100%, and, B: 0~0.0030%, Zn: 0~0.0030%, Ge: 0~0.0030%, As: 0~0.0100%, Co: 0~0.0500%, V: 0~0.0030%, Se: 0~0.0030%, Zr: 0~0.0030%, Nb: 0~0.0030%, Pb: 0~0.0030%, and Ga: 0~0.0030%, with the remainder consisting of Fe and impurities. (Feature 2) The plate thickness t is less than 0.30mm. (Feature 3) The F1 defined by equation (1) is 10.0 or higher. F1 = 4Si + 3Al + 2Mn (1) Here, the symbols of each element in equation (1) represent the content of the corresponding element expressed as a percentage of mass. (Feature 4) The F2 defined by equation (2) is 8.5 or less. F2=2Si+3Al+Mn (2) Here, the symbols of each element in equation (2) represent the content of the corresponding element expressed as a percentage of mass. (Feature 5) The F3 defined in equation (3) is the iron loss W5 / 1000 or less, and this iron loss W5 / 1000 is the iron loss at a frequency of 1000Hz and a magnetic flux density of 0.5T. F4 as defined in Equation (4) is an iron loss W10 / 400 or higher, and the iron loss W10 / 400 is the iron loss of a non-directional electromagnetic steel plate at a frequency of 400Hz and a magnetic flux density of 1.0T after heat treatment at 800℃ for 1 hour. F3=45-12Si-5Al-2Mn+1000×t / (5+6Si+5Al+3Mn) (3) F4=4+800×t / (5+6Si+5Al+3Mn) (4) Here, the element symbols in equations (3) and (4) are the content of the corresponding element in terms of mass % and t is the thickness of the plate mentioned above in mm. The following explanation addresses features 1 through 5.

[0040] [Regarding (Characteristic 1) Chemical Composition] The chemical composition of the non-directional electromagnetic steel sheet of this embodiment contains the following elements. Furthermore, unless otherwise specified, "%" in the chemical composition of the non-directional electromagnetic steel sheet refers to mass.

[0041] Si: 2.0~4.0% Silicon (Si) increases the resistivity of the steel sheet and reduces eddy current losses. As a result, the iron loss of the steel sheet is reduced. Si also dissolves in the steel sheet, thereby increasing its strength. If the Si content is less than 2.0%, the above effects cannot be fully achieved even if the contents of other elements are within the range of this embodiment. On the other hand, if the Si content is greater than 4.0%, the punching processability of the non-directional electromagnetic steel sheet will still be reduced even if the contents of other elements are within the range of this embodiment. Therefore, the Si content is 2.0~4.0%. The suitable lower limit for Si content is 2.1%, more preferably 2.2%, more preferably 2.3%, more preferably 2.5%, and more preferably 2.8%. The suitable upper limit for Si content is 3.7%, more preferably 3.6%, more preferably 3.5%, and more preferably 3.2%.

[0042] Mn: 0.1~1.5% Manganese (Mn) increases the resistivity of steel sheets and reduces eddy current losses. As a result, the iron loss of the steel sheet is reduced. If the Mn content is less than 0.1%, the above-mentioned effects cannot be fully obtained even if the contents of other elements are within the range of this embodiment. On the other hand, if the Mn content is greater than 1.5%, the magnetic flux density of the steel plate will still decrease even if the contents of other elements are within the range of this embodiment. Therefore, the Mn content is 0.1~1.5%. The appropriate lower limit for Mn content is 0.2%, more preferably 0.3%, and even more preferably 0.4%. The appropriate upper limit for Mn content is 1.0%, preferably 0.8%, preferably 0.7%, and preferably 0.6%.

[0043] P: below 0.15% Phosphorus (P) is unavoidable; that is, the P content is greater than 0%. P increases the strength of steel plates through solid solution strengthening. Even if the P content is low, a certain degree of the above-mentioned effect can still be obtained if P is present. However, if the phosphorus (P) content is greater than 0.15%, even if the contents of other elements are within the range of this embodiment, the steel sheet will still become brittle and its workability will decrease, and sometimes cracks will occur in the steel sheet during cold rolling. Therefore, the P content is 0.15% or less. The appropriate lower limit for phosphorus content is 0.01%, and more preferably 0.03%. The appropriate upper limit for phosphorus content is 0.12%, more preferably 0.10%, and even more preferably 0.08%.

[0044] S: below 0.0030% Sulfur (S) is an unavoidable impurity. That is, the S content is greater than 0%. If the S content is greater than 0.0030%, even if the contents of other elements are within the range of this embodiment, S will still excessively generate sulfides such as MnS. These sulfides will degrade the iron loss and magnetic flux density of the steel plate. Therefore, the S content is 0.0030% or less. The lower the sulfur content, the better. However, if the sulfur content is reduced excessively, the manufacturing cost will increase. Therefore, from an industrial productivity point of view, the appropriate lower limit for sulfur content is greater than 0.0001%, more preferably 0.0003%, more preferably 0.0004%, and more preferably 0.0005%. The appropriate upper limit for sulfur content is 0.0020%, more preferably 0.0018%, more preferably 0.0017%, more preferably 0.0015%, more preferably 0.0010%, and more preferably 0.0008%.

[0045] Al: 0.1~2.0% Aluminum (Al) increases the resistivity of steel sheets and reduces eddy current losses. As a result, the iron loss of the steel sheet is reduced. If the Al content is less than 0.1%, the above-mentioned effects cannot be fully obtained even if the contents of other elements are within the range of this embodiment. On the other hand, if the Al content is greater than 2.0%, the magnetic flux density of the steel will still decrease even if the contents of other elements are within the range of this embodiment. Therefore, the Al content is 0.1~2.0%. The suitable lower limit for Al content is 0.2%, more preferably 0.3%, and even more preferably 0.4%. The appropriate upper limit for Al content is 1.8%, with 1.6% being more suitable and 1.4% even better. In this specification, the Al content in the chemical composition of non-directional electromagnetic steel sheet refers to the content of acid-soluble Al (sol.Al).

[0046] C: Below 0.0050% Carbon (C) adheres tightly to the steel sheet, increasing its strength. Even small amounts of C can achieve some degree of this effect. However, if the C content is greater than 0.0050%, even if the contents of other elements are within the range of this embodiment, excessive carbides will still be generated, which will degrade the iron loss and magnetic flux density of the steel plate. Therefore, the C content is below 0.0050%. The appropriate lower limit for C content is greater than 0%, more preferably 0.0001%; ​​greater than 0.0001%, more preferably 0.0005%; more preferably 0.0008%; more preferably 0.0010%. The appropriate upper limit for C content is 0.0040%, more preferably 0.0036%, more preferably 0.0030%, more preferably 0.0025%, and more preferably 0.0020%.

[0047] N: below 0.0050% Nitrogen (N) is an unavoidable impurity. That is, the N content is greater than 0%. If the N content is greater than 0.0050%, even if the contents of other elements are within the range of this embodiment, N will still form excessive nitrides in the steel plate, which will degrade the iron loss and magnetic flux density of the steel plate. Therefore, the nitrogen content is below 0.0050%. The lower the nitrogen content, the better. However, if the nitrogen content is reduced excessively, the manufacturing cost will increase. Therefore, from an industrial production point of view, the appropriate lower limit for nitrogen content is 0.0001%, more preferably 0.0005%, more preferably 0.0010%, more preferably 0.0013%, and more preferably 0.0015%. The appropriate upper limit for nitrogen content is 0.0040%, more preferably 0.0030%, and even more preferably 0.0025%.

[0048] O: Below 0.0500% Oxygen (O) is an unavoidable impurity. That is, the O content is greater than 0%. If the O content is greater than 0.0500%, even if the contents of other elements are within the range of this embodiment, O will still form excessive oxides in the steel plate, which will degrade the iron loss and magnetic flux density of the steel plate. Therefore, the O content is below 0.0500%. The lower the O content, the better. However, if the O content is reduced excessively, the manufacturing cost will increase. Therefore, from an industrial production point of view, the appropriate lower limit for O content is 0.0001%, more preferably 0.0005%, more preferably 0.0010%, and more preferably 0.0015%. The appropriate upper limit for O content is 0.0200%, more preferably 0.0100%, more preferably 0.0050%, and more preferably 0.0030%.

[0049] The remaining chemical composition of the non-directional electromagnetic steel sheet of this embodiment consists of Fe and impurities. Impurities here refer to components that are unintentionally introduced during the industrial manufacturing of the non-directional electromagnetic steel sheet from raw materials such as ore or waste, or from the manufacturing environment. The content of these impurities is permissible as long as they do not adversely affect the non-directional electromagnetic steel sheet of this embodiment.

[0050] [Optional Elements] The chemical composition of the non-directional electromagnetic steel sheet of this embodiment may also contain one or more elements selected from the following group to replace a portion of Fe: Cr: 0~0.50%, Ti: 0~0.0030%, Mo: 0~0.100%, Ni: 0~0.50%, Cu: 0~0.50%, Sn: 0~0.100%, Sb: 0~0.100%, Ca: 0~0.0050%, Mg: 0~0.0030%. Rare earth elements: 0~0.0100%, B: 0~0.0030%, Zn: 0~0.0030%, Ge: 0~0.0030%, As: 0~0.0100%, Co: 0~0.0500%, V: 0~0.0030%, Se: 0~0.0030%, Zr: 0~0.0030%, Nb: 0~0.0030%, Pb: 0~0.0030%, and Ga: 0~0.0030%. The following descriptions will focus on any of these elements.

[0051] [Group 1: Cr] The chemical composition of the non-directional electromagnetic steel sheet in this embodiment may also contain Cr to replace a portion of Fe.

[0052] Cr: 0~0.50% Chromium (Cr) can be any element, or it can be absent. That is, the Cr content can be 0%. If Cr is present, that is, when the Cr content is greater than 0%, Cr, like Si, will increase the resistivity of the steel sheet and reduce eddy current losses. As a result, the iron loss of the steel sheet will decrease. Even a small amount of Cr can achieve the above-mentioned effects to some extent. However, if the Cr content is greater than 0.50%, the magnetic flux density of the steel plate will decrease. Therefore, the Cr content is 0~0.50%. The appropriate lower limit for Cr content is 0.01%, more preferably 0.02%, and even more preferably 0.03%. The appropriate upper limit for Cr content is 0.40%, more preferably 0.35%, more preferably 0.30%, and more preferably 0.10%.

[0053] [Group 2: Ti, Mo, Ni, and Cu] The chemical composition of the non-directional electromagnetic steel sheet of this embodiment may also contain one or more elements selected from the group consisting of Ti, Mo, Ni, and Cu to replace a portion of the Fe. These elements are arbitrary and will all increase the strength of the steel sheet. The following is an explanation of each element.

[0054] Ti: 0~0.0030% Titanium (Ti) can be any element, or it can be absent. That is, the Ti content can be 0%. If Ti is present, that is, if the Ti content is greater than 0%, Ti will form carbonitrides and increase the strength of the non-directional electromagnetic steel sheet through precipitation strengthening. Even a small amount of Ti can achieve the above-mentioned effect to some extent. However, if the Ti content is greater than 0.0030%, even if the contents of other elements are within the range of this embodiment, carbonitrides will still be generated in excess and the magnetic properties will deteriorate. Therefore, the Ti content is 0~0.0030%. The appropriate lower limit for Ti content is 0.0001%, more preferably 0.0005%, and even more preferably 0.0010%. The appropriate upper limit for Ti content is 0.0025%, more preferably 0.0020%, and even more preferably 0.0017%.

[0055] Mo: 0~0.100% Molybdenum (Mo) can be any element, or it can be absent. That is, the Mo content can be 0%. If the material contains Mo, that is, when the Mo content is greater than 0%, Mo will form carbonitrides and increase the strength of the non-directional electromagnetic steel sheet through precipitation strengthening. Even a small amount of Mo can achieve the above-mentioned effect to some extent. However, if the Mo content is greater than 0.100%, even if the contents of other elements are within the range of this embodiment, carbides will still be generated in excess and the magnetic properties will deteriorate. Therefore, the Mo content is 0~0.100%. The appropriate lower limit for Mo content is 0.001%, more preferably 0.005%, more preferably 0.010%, and more preferably 0.015%. The appropriate upper limit for Mo content is 0.090%, more preferably 0.080%, more preferably 0.075%, and more preferably 0.070%.

[0056] Ni: 0~0.50% Nickel (Ni) can be any element, or it can be absent. That is, the Ni content can be 0%. If Ni is present, that is, when the Ni content is greater than 0%, Ni will increase the strength of the steel plate through solid solution strengthening. Even a small amount of Ni can achieve the above-mentioned effect to some extent. However, if the Ni content is greater than 0.50%, the steel plate will still become brittle and its workability will be reduced, even if the contents of other elements are within the range of this embodiment. Therefore, the Ni content is 0~0.50%. The appropriate lower limit for Ni content is 0.01%, more preferably 0.02%, and even more preferably 0.03%. The appropriate upper limit for Ni content is 0.35%, more preferably 0.20%, and even more preferably 0.10%.

[0057] Cu: 0~0.50% Copper (Cu) can be any element, or it can be absent. That is, the Cu content can be 0%. If it is present, Cu will increase the strength of the non-directional electromagnetic steel sheet. Even a small amount of Cu can achieve the above-mentioned effect to some extent. However, if the Cu content is greater than 0.50%, the steel sheet will become brittle and its workability will decrease. Therefore, the Cu content is 0~0.50%. The appropriate lower limit for Cu content is 0.01%, more preferably 0.02%, and even more preferably 0.03%. The appropriate upper limit for Cu content is 0.30%, more preferably 0.20%, more preferably 0.15%, and more preferably 0.10%.

[0058] [Group 3: Sn, Sb, Ca, Mg and Rare Earth Elements (REM)] The chemical composition of the non-directional electromagnetic steel sheet of this embodiment may also contain one or more elements selected from the group consisting of Sn, Sb, Ca, Mg, and rare earth elements (REM) to replace a portion of the Fe. These elements are arbitrary and will all improve the magnetic properties of the steel sheet. The following is an explanation of each element.

[0059] Sn: 0~0.100% Tin (Sn) can be any element, or it can be absent. That is, the Sn content can be 0%. If Sn is present, that is, when the Sn content is greater than 0%, Sn will segregate on the surface of the steel sheet, inhibiting oxidation and nitriding during finishing annealing. This reduces the iron loss of the non-directional electromagnetic steel sheet. Sn also improves the aggregate structure of the steel sheet, thereby increasing the magnetic flux density. Even a small amount of Sn can achieve these effects to some extent. However, if the Sn content is greater than 0.100%, the steel plate will still become brittle and its workability will be reduced, even if the contents of other elements are within the range of this embodiment. Therefore, the Sn content is 0~0.100%. The suitable lower limit for Sn content is 0.001%, more preferably 0.005%, and even more preferably 0.010%. The suitable upper limit for Sn content is 0.080%, more preferably 0.070%, and even more preferably 0.060%.

[0060] Sb: 0~0.100% Antimony (Sb) can be any element, or it can be absent. That is, the Sb content can be 0%. If Sb is present, that is, when the Sb content is greater than 0%, Sb will segregate on the surface of the steel sheet, inhibiting oxidation and nitriding during finishing annealing. This reduces the iron loss of the non-directional electromagnetic steel sheet. Sb also improves the aggregate structure of the steel sheet, thereby increasing the magnetic flux density. Even a small amount of Sb can achieve these effects to some extent. However, if the Sb content is greater than 0.100%, the steel plate will still become brittle and its workability will be reduced, even if the contents of other elements are within the range of this embodiment. Therefore, the Sb content is 0~0.100%. The appropriate lower limit for Sb content is 0.001%, more preferably 0.003%, more preferably 0.005%, and more preferably 0.010%. The appropriate upper limit for Sb content is 0.080%, more preferably 0.070%, more preferably 0.060%, more preferably 0.040%, more preferably 0.030%, and more preferably 0.020%.

[0061] Ca: 0~0.0050% Calcium (Ca) can be any element, or it can be absent. That is, the Ca content can be 0%. If the material contains more than 0% Ca, Ca will bond with S during casting to form coarse sulfides and / or coarse oxysulfides, resulting in coarse precipitates. These coarse sulfides will adsorb inhibitory substances in subsequent manufacturing steps, such as fine MnS, TiN, and AlN particles with a diameter of approximately 100 nm that form in the steel sheet. This inhibits grain growth during finishing annealing, thus promoting grain growth. Consequently, the magnetic properties of the non-directional electromagnetic steel sheet are improved. Even a small amount of Ca can achieve this effect to some extent. However, if the Ca content is greater than 0.0050%, coarse precipitates will still be generated excessively, even if the contents of other elements are within the range of this embodiment. In this case, recrystallization and grain growth in the finishing annealing step will be hindered. Therefore, the Ca content is 0~0.0050%. The appropriate lower limit for Ca content is 0.0001%, more preferably 0.0005%, and even more preferably 0.0010%. The appropriate upper limit for Ca content is 0.0040%, more preferably 0.0035%, more preferably 0.0030%, and more preferably 0.0025%.

[0062] Mg: 0~0.0030% Magnesium (Mg) can be any element, or it can be absent. That is, the Mg content can be 0%. If Mg is present, meaning the Mg content is greater than 0%, Mg, like Ca, will form coarse precipitates. Furthermore, during finishing annealing, the inhibition of grain growth by these inhibitory substances will be suppressed. Therefore, grain growth will be promoted during finishing annealing. As a result, the magnetic properties of the non-directional electromagnetic steel sheet will be improved. Even a small amount of Mg can achieve the above-mentioned effects to some extent. However, if the Mg content is greater than 0.0030%, coarse precipitates will still be generated excessively, even if the contents of other elements are within the range of this embodiment. In this case, recrystallization and grain growth in the finishing annealing step will be hindered. Therefore, the Mg content is 0~0.0030%. The suitable lower limit for Mg content is 0.0001%, more preferably 0.0002%, and even more preferably 0.0003%. The upper limit of the suitable Mg content is 0.0020%, more preferably 0.0015%, and even more preferably 0.0010%.

[0063] Rare Earth Elements (REM): 0~0.0100% Rare earth elements (REM) are any element, or they may not be present. That is, the REM content can be 0%. If REM is present, that is, when the REM content is greater than 0%, REM, like Ca, will form coarse precipitates. Furthermore, during finishing annealing, the inhibition of grain growth by this inhibitory substance will be suppressed. Therefore, grain growth will be promoted during finishing annealing. As a result, the magnetic properties of the non-directional electromagnetic steel sheet will be improved. Even a small amount of REM can achieve the above-mentioned effects to some extent. However, if the REM content is greater than 0.0100%, coarse precipitates will still be generated excessively, even if the contents of other elements are within the range of this embodiment. In this case, recrystallization and grain growth in the finishing annealing step will be hindered. Therefore, the REM content is 0~0.0100%. The appropriate lower limit for REM content is 0.0001%, more preferably 0.0005%, and even more preferably 0.0010%. The appropriate upper limit for REM content is 0.0050%, more preferably 0.0045%, more preferably 0.0040%, and more preferably 0.0030%.

[0064] Furthermore, in this specification, REM refers to one or more elements selected from the group consisting of scandium (Sc) atomic number 21, yttrium (Y) atomic number 39, and the lanthanides, namely lanthanum (La) atomic number 57 to illuminum (Lu) atomic number 71. Also, in this specification, REM content refers to the total content of these elements.

[0065] [Group 4:B] The chemical composition of the non-directional electromagnetic steel sheet in this embodiment may also contain B to replace a portion of Fe.

[0066] B: 0~0.0030% Boron (B) can be any element, or it can be absent. That is, the B content can be 0%. If it contains B, that is, when the B content is greater than 0%, B will form nitrides and hinder recrystallization during finishing annealing. Therefore, the content of B is 0~0.0030%. Excessively reducing the B content will increase manufacturing costs. Therefore, from an industrial productivity point of view, the appropriate lower limit for the B content is 0.0001%, more preferably 0.0002%, and even more preferably 0.0003%. The appropriate upper limit for B content is 0.0020%, more preferably 0.0015%, more preferably 0.0010%, and more preferably 0.0007%.

[0067] [Group 5: Zn, Ge, As, and Co] The chemical composition of the non-directional electromagnetic steel sheet in this embodiment may also contain one or more elements selected from the group consisting of Zn, Ge, As, and Co, to replace a portion of the Fe. These elements are arbitrary and will all reduce the iron loss of the non-directional electromagnetic steel sheet. The following is an explanation of each element.

[0068] Zn: 0~0.0030% Zinc (Zn) can be any element, or it can be absent. That is, the Zn content can be 0%. If Zn is present, that is, when the Zn content is greater than 0%, Zn will inhibit the formation of oxides and sulfides and reduce the iron loss of non-directional electromagnetic steel sheets. Even a small amount of Zn can still achieve the above-mentioned effects to some extent. However, if the Zn content is greater than 0.0030%, the above effect will still be saturated even if the contents of other elements are within the range of this embodiment. Therefore, the Zn content is 0~0.0030%. The appropriate lower limit for Zn content is 0.0001%, more preferably 0.0003%, and even more preferably 0.0005%. The appropriate upper limit for Zn content is 0.0025%, more preferably 0.0020%, and even more preferably 0.0015%.

[0069] Ge: 0~0.0030% Germanium (Ge) can be any element, or it can be absent. That is, the Ge content can be 0%. If the material contains Ge (Ge), meaning the Ge content is greater than 0%, Ge will reduce the iron loss of the non-directional electromagnetic steel sheet. Ge will also increase the magnetic flux density. Even a small amount of Ge can achieve these effects to some extent. However, if the Ge content is greater than 0.0030%, the above effect will still be saturated even if the contents of other elements are within the range of this embodiment. Therefore, the Ge content is 0~0.0030%. The appropriate lower limit for Ge content is 0.0001%, more preferably 0.0003%, and even more preferably 0.0005%. The appropriate upper limit for Ge content is 0.0025%, more preferably 0.0020%, and even more preferably 0.0015%.

[0070] As: 0~0.0100% Arsenic (As) can be any element, or it can be absent. That is, the As content can be 0%. If As is present, that is, when the As content is greater than 0%, As will reduce the iron loss of the non-directional electromagnetic steel sheet. As will also increase the magnetic flux density. Even a small amount of As can still achieve the above effects to some extent. However, if the As content is greater than 0.0100%, the above effect will still be saturated even if the contents of other elements are within the range of this embodiment. Therefore, the As content is 0~0.0100%. The appropriate lower limit for As content is 0.0001%, more preferably 0.0005%, and even more preferably 0.0010%. The appropriate upper limit for As content is 0.0080%, with 0.0060% and 0.0045% being more suitable, and 0.0040% being even more suitable.

[0071] Co: 0~0.0500% Cobalt (Co) can be any element, or it can be absent. That is, the Co content can be 0%. If the Co content is greater than 0%, it will reduce the iron loss of the non-directional electromagnetic steel sheet. Co will also increase the magnetic flux density. Even a small amount of Co can achieve these effects to some extent. However, if the Co content is greater than 0.0500%, the above effect will still be saturated even if the contents of other elements are within the range of this embodiment. Therefore, the Co content is 0~0.0500%. The appropriate lower limit for Co content is 0.0001%, and more preferably 0.0010%. The appropriate upper limit for Co content is 0.0400%, more preferably 0.0300%, more preferably 0.0200%, more preferably 0.0100%, and more preferably 0.0065%.

[0072] [Group 6: V, Se, Zr, Nb, Pb, and Ga] The chemical composition of the non-directional electromagnetic steel sheet in this embodiment may also contain one or more elements selected from the group consisting of V, Se, Zr, Nb, Pb, and Ga, to replace a portion of the Fe. These elements are impurities and will degrade iron loss. The following is a description of each element.

[0073] V: 0~0.0030% Vanadium (V) is an impurity, but it may also be absent. That is, the V content can be 0%. If V is present, that is, if the V content is greater than 0%, V will form fine precipitates, which will degrade the iron loss of the non-directional electromagnetic steel sheet. If the V content is greater than 0.0030%, the iron loss of the non-directional electromagnetic steel sheet will still be significantly degraded even if the contents of other elements are within the range of this embodiment. Therefore, the V content is 0~0.0030%. The lower the vitamin C content, the better. However, excessively reducing the vitamin C content will increase manufacturing costs. Therefore, considering general industrial production, the appropriate lower limit for vitamin C content is 0.0001%, more preferably 0.0003%, and even more preferably 0.0005%. The appropriate upper limit for vitamin V content is 0.0025%, more preferably 0.0020%, and even more preferably 0.0015%.

[0074] Se: 0~0.0030% Selenium (Se) is an impurity, but it can also be absent. That is, the Se content can be 0%. If the Se content is greater than 0%, it will form fine precipitates, which will degrade the iron loss of the non-directional electromagnetic steel sheet. If the Se content is greater than 0.0030%, the iron loss of the non-directional electromagnetic steel sheet will still be significantly degraded even if the contents of other elements are within the range of this embodiment. Therefore, the Se content is 0~0.0030%. The lower the selenium (Se) content, the better. However, excessively reducing the Se content will increase manufacturing costs. Therefore, considering general industrial production, the appropriate lower limit for the Se content is 0.0001%, more preferably 0.0003%, and even more preferably 0.0005%. The appropriate upper limit for Se content is 0.0025%, more preferably 0.0020%, and even more preferably 0.0015%.

[0075] Zr: 0~0.0030% Zirconium (Zr) is an impurity, but it may also be absent. That is, the Zr content can be 0%. If Zr is present, that is, when the Zr content is greater than 0%, Zr will form fine precipitates, which will degrade the iron loss of the non-directional electromagnetic steel sheet. If the Zr content is greater than 0.0030%, the iron loss of the non-directional electromagnetic steel sheet will still be significantly degraded even if the contents of other elements are within the range of this embodiment. Therefore, the Zr content is 0~0.0030%. The lower the Zr content, the better. However, excessively reducing the Zr content will increase manufacturing costs. Therefore, considering general industrial production, the appropriate lower limit for Zr content is 0.0001%, more preferably 0.0003%, and even more preferably 0.0005%. The appropriate upper limit for Zr content is 0.0025%, more preferably 0.0020%, and even more preferably 0.0015%.

[0076] Nb: 0~0.0030% Niobium (Nb) is an impurity, but it may also be absent. That is, the Nb content can be 0%. If Nb is present, that is, when the Nb content is greater than 0%, Nb will form fine precipitates, which will degrade the iron loss of the non-directional electromagnetic steel sheet. If the Nb content is greater than 0.0030%, the iron loss of the non-directional electromagnetic steel sheet will still be significantly degraded even if the contents of other elements are within the range of this embodiment. Therefore, the Nb content is 0~0.0030%. The lower the Nb content, the better. However, excessively reducing the Nb content will increase manufacturing costs. Therefore, considering general industrial production, the appropriate lower limit for Nb content is 0.0001%, more preferably 0.0003%, and even more preferably 0.0005%. The appropriate upper limit for Nb content is 0.0025%, more preferably 0.0020%, and even more preferably 0.0015%.

[0077] Pb: 0~0.0030% Lead (Pb) is an impurity, but it can also be absent. That is, the Pb content can be 0%. If Pb is present, that is, when the Pb content is greater than 0%, Pb will form fine Pb particles, which will degrade the iron loss of the non-directional electromagnetic steel sheet. If the Pb content is greater than 0.0030%, the iron loss of the non-directional electromagnetic steel sheet will still be significantly degraded even if the contents of other elements are within the range of this embodiment. Therefore, the Pb content is 0~0.0030%. The lower the Pb content, the better. However, excessively reducing the Pb content will increase manufacturing costs. Therefore, considering general industrial production, the appropriate lower limit for Pb content is 0.0001%, more preferably 0.0003%, and even more preferably 0.0005%. The appropriate upper limit for Pb content is 0.0025%, more preferably 0.0020%, and even more preferably 0.0015%.

[0078] Ga: 0~0.0030% Gallium (Ga) is an impurity, but it can also be absent. That is, the Ga content can be 0%. If Ga is present, that is, if the Ga content is greater than 0%, Ga will form fine precipitates, which will degrade the iron loss of the non-directional electromagnetic steel sheet. If the Ga content is greater than 0.0030%, the iron loss of the non-directional electromagnetic steel sheet will still be significantly degraded even if the contents of other elements are within the range of this embodiment. Therefore, the Ga content is 0~0.0030%. The lower the Ga content, the better. However, excessively reducing the Ga content will increase manufacturing costs. Therefore, considering general industrial production, the appropriate lower limit for Ga content is 0.0001%, more preferably 0.0003%, and even more preferably 0.0005%. The appropriate upper limit for Ga content is 0.0025%, more preferably 0.0020%, and even more preferably 0.0015%.

[0079] [Method for determining the chemical composition of non-directional electromagnetic steel sheets] The chemical composition of the non-directional electromagnetic steel sheet of this embodiment can be determined using known composition analysis methods according to JIS G0321:2017. Specifically, shavings are taken from the steel sheet using a drill. The shavings are dissolved in acid to obtain a solution. Elemental analysis of the chemical composition is performed on the solution using ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrometry). The C, S, and O contents are determined using a known high-frequency combustion method (combustion-infrared absorption method). The N content is determined using a known inert gas melt-thermal conductivity method.

[0080] [Regarding (Special Feature 2) Plate Thickness t] In this embodiment of the non-directional electromagnetic steel sheet, the sheet thickness t is 0.30 mm or less. Because the sheet thickness t is 0.30 mm or less, eddy current losses are reduced. The suitable lower limit for plate thickness t is 0.14mm, more suitable is 0.15mm, more suitable is 0.19mm, more suitable is 0.20mm, more suitable is 0.21mm, and more suitable is 0.24mm. The suitable upper limit for plate thickness t is 0.29mm, more preferably 0.27mm, and even more preferably 0.25mm.

[0081] [Method for determining the thickness t of non-directional electromagnetic steel sheet] The thickness t of the non-directional electromagnetic steel sheet is obtained by the following method: The sheet thickness is measured at 10 measurement positions on the non-directional electromagnetic steel sheet. Each measurement position is located on a line segment inclined at 45° from the rolling direction, with a distance of 1.0 mm between adjacent measurement points. The arithmetic mean of the 10 measured thicknesses is taken as the sheet thickness t (mm) of the non-directional electromagnetic steel sheet. The thickness is a value up to two decimal places, obtained by rounding the arithmetic mean to the third decimal place. A micrometer is used for measurement.

[0082] [About (Special Feature 3) F1] In the non-directional electromagnetic steel sheet of this embodiment, F1 as defined in equation (1) is 10.0 or higher. F1 = 4Si + 3Al + 2Mn (1) Here, the symbols of each element in equation (1) represent the content of the corresponding element expressed as a percentage of mass.

[0083] F1 is the resistivity index of a non-directional electromagnetic steel sheet that satisfies characteristic 1. If F1 is less than 10.0, even if the non-directional electromagnetic steel sheet meets other characteristics, it is impossible to obtain a sufficiently high resistivity. As a result, low iron loss cannot be sufficiently obtained in non-directional electromagnetic steel sheets. If F1 is 10.0 or higher, then, provided that other characteristics are met, a sufficiently high resistivity can be obtained in non-directional electromagnetic steel sheets. As a result, excellent iron loss can be obtained in non-directional electromagnetic steel sheets.

[0084] The appropriate lower limit for F1 is 10.3, more appropriate is 10.5, more appropriate is 11.5, more appropriate is 12.0, and more appropriate is 12.5. There is no specific upper limit for F1. However, if F1 is too high, the thermal conductivity of the non-directional electromagnetic steel sheet will decrease. Accordingly, the suitable upper limit for F1 is 17.0, more preferably 16.0, more preferably 15.5, more preferably 15.0, more preferably 14.5, and more preferably 14.0.

[0085] [Regarding (Special Feature 4) F2] In the non-directional electromagnetic steel sheet of this embodiment, F2 as defined in equation (2) is 8.5 or less. F2=2Si+3Al+Mn (2) Here, the symbols of each element in equation (2) represent the content of the corresponding element expressed as a percentage of mass.

[0086] F2 is the saturation magnetic flux density of a non-directional electromagnetic steel sheet that satisfies characteristic 1. If F2 is greater than 8.5, even if the non-directional electromagnetic steel sheet satisfies other characteristics, a sufficiently high magnetic flux density cannot be obtained. Furthermore, if F2 is greater than 8.5, the thermal conductivity may sometimes decrease. If F2 is less than 8.5, a sufficiently high magnetic flux density can be obtained in a non-directional electromagnetic steel sheet, provided that other characteristics are satisfied.

[0087] The appropriate lower limit for F2 is 5.0, with 5.5 being more suitable, 5.8 being more suitable, and 6.0 being more suitable. The optimal upper limit for F2 is 8.3, with 8.2 being more suitable, 8.0 being more suitable, 7.8 being more suitable, 7.6 being more suitable, and 7.5 being more suitable.

[0088] [Regarding (Special Feature 5) F3 and F4] In the non-directional electromagnetic steel sheet of this embodiment, further, F3 as defined by formula (3) is an iron loss W5 / 1000 or less and the iron loss W5 / 1000 is the iron loss at a frequency of 1000Hz and a magnetic flux density of 0.5T, and F4 as defined by formula (4) is an iron loss W10 / 400 or more and the iron loss W10 / 400 is the iron loss at a frequency of 400Hz and a magnetic flux density of 1.0T after the non-directional electromagnetic steel sheet has been heat-treated at 800°C for 1 hour. F3=45-12Si-5Al-2Mn+1000×t / (5+6Si+5Al+3Mn) (3) F4=4+800×t / (5+6Si+5Al+3Mn) (4) Here, the element symbols in equations (3) and (4) are the content of the corresponding element in terms of mass % and t is the plate thickness in terms of mm. The following explanation addresses F3 and F4.

[0089] F3 and F4 are indices regarding the strain and strain distribution in the microstructure of the non-directional electromagnetic steel sheet. As described above, in the non-directional electromagnetic steel sheet of this embodiment, in order to obtain high strength, high magnetic flux density, and excellent iron loss after relaxation annealing, the alloy element content in the steel sheet is deliberately reduced, and specific strain and strain distributions are introduced into the steel sheet. As a result, for non-directional electromagnetic steel sheets used as rotor cores, they can be used as rotor core materials without relaxation annealing, thereby producing rotor cores with high strength and excellent magnetic flux density. Furthermore, for non-directional electromagnetic steel sheets used as stator cores, they can be used as stator core materials after relaxation annealing, thereby producing stator cores with excellent iron loss and excellent magnetic flux density.

[0090] It is extremely difficult to quantitatively demonstrate the strain and strain distribution in a steel plate. Therefore, in this embodiment, F3 and F4 are used as indicators of the strain and strain distribution in the steel plate.

[0091] [About F3] If F3 is greater than the iron loss W5 / 1000, and this iron loss W5 / 1000 is the iron loss at a frequency of 1000Hz and a magnetic flux density of 0.5T, then the strain introduced into the steel plate is too small, or the strain distribution in the steel plate is inappropriate. Therefore, high strength cannot be sufficiently obtained in non-directional electromagnetic steel plates. If F3 is less than or equal to the iron loss W5 / 1000, then a sufficient amount of strain is introduced into the steel plate, and the distribution of the introduced strain is also appropriate. Therefore, in non-directional electromagnetic steel plates, a high magnetic flux density can be obtained under the premise that characteristics 1 to 4 are satisfied, F4 is greater than or equal to the iron loss W10 / 400, and that the iron loss W10 / 400 is the iron loss after heat treatment at 800°C for 1 hour.

[0092] The appropriate lower limit for F3 is 0.40 times the iron loss W5 / 1000, more preferably 0.50 times the iron loss W5 / 1000, and even more preferably 0.60 times the iron loss W5 / 1000. The appropriate upper limit for F3 is 0.90 times the iron loss W5 / 1000, more preferably 0.87 times the iron loss W5 / 1000, and even more preferably 0.85 times the iron loss W5 / 1000.

[0093] [About F4] If F4 is less than the iron loss W10 / 400, and this iron loss W10 / 400 is the iron loss of a non-directional electromagnetic steel sheet after heat treatment at 800°C for 1 hour at a frequency of 400Hz and a magnetic flux density of 1.0T, then the strain introduced into the steel sheet before relaxation annealing is not sufficiently reduced. Alternatively, the strain distribution in the steel sheet may be inappropriate. In this case, using it as a stator will not result in sufficiently low iron loss. Furthermore, strain will hinder magnetization, thus reducing the magnetic flux density B1, especially in a magnetic field of 100 A / m.

[0094] If F4 is an iron loss W10 / 400 or higher, and this iron loss W10 / 400 is the iron loss after heat treatment at 800°C for 1 hour, then a sufficient amount of strain can be reduced from the steel sheet, and the distribution of the introduced strain is also appropriate. Therefore, in non-directional electromagnetic steel sheets, under the premise of satisfying characteristics 1 to 4 and F3 being an iron loss W5 / 1000 or lower, excellent iron loss and excellent magnetic flux density can be obtained in non-directional electromagnetic steel sheets after stress-relaxation annealing.

[0095] The appropriate lower limit for F4 is 1.01 times the iron loss W10 / 400, more preferably 1.02 times the iron loss W10 / 400, and even more preferably 1.05 times the iron loss W10 / 400. The appropriate upper limit for F4 is 1.50 times the iron loss W10 / 400, more preferably 1.40 times the iron loss W10 / 400, and even more preferably 1.30 times the iron loss W10 / 400.

[0096] [Method for determining the iron loss W5 / 1000 of non-directional electromagnetic steel sheets] The iron loss W5 / 1000 of the non-directional electromagnetic steel sheet in this embodiment is obtained by the Epstein test method shown below. According to JIS C 2550-1:2011 and 2550-3:2019, several Epstein test pieces were cut from non-directional electromagnetic steel sheets. The dimensions of the Epstein test pieces were set at 30 mm wide and 280 mm long. Several L-direction test pieces with the length direction of the non-directional electromagnetic steel sheet rolling direction and several C-direction test pieces with the length direction perpendicular to the non-directional electromagnetic steel sheet rolling direction were cut as Epstein test pieces. The number of L-direction test pieces and C-direction test pieces were the same, with a total of 16 test pieces (8 L-direction test pieces and 8 C-direction test pieces).

[0097] Test pieces in the L-direction and C-direction directions are arranged within an Epstein frame. With the four sides of the Epstein frame parallel to the X or Y direction, four L-direction test pieces are placed on each pair of sides parallel to the X direction. Four C-direction test pieces are placed on each pair of sides parallel to the Y direction. The ends of the L-direction and C-direction test pieces are stacked in an alternating overlapping manner. This forms a square. For the squared Epstein test pieces, the iron loss W5 / 1000 (W / kg) at 1000Hz and 0.5T is measured according to the electromagnetic steel strip test methods of JIS C 2550-1:2011 and 2550-3:2019.

[0098] [Method for determining the iron loss W10 / 400 of non-directional electromagnetic steel sheets after stress-relaxation annealing] The iron loss W10 / 400 of the non-directional electromagnetic steel sheet after relaxation annealing in this embodiment is obtained by the following method: Several Epstein test pieces (8 L-direction test pieces and 8 C-direction test pieces) are cut from the non-directional electromagnetic steel sheet according to the method described in [Method for Determining Iron Loss W5 / 1000 of Non-directional Electromagnetic Steel Sheets]. The cut Epstein test pieces (L-direction test pieces and C-direction test pieces) are subjected to heat treatment (relaxation annealing). During heat treatment, the heat treatment temperature is set to 800°C, and the holding time at the heat treatment temperature is set to 1 hour. Furthermore, the temperature and time are based on the temperature of the Epstein test pieces themselves, not the temperature of the annealing furnace (furnace temperature). Relaxation annealing is performed in the state after the Epstein test pieces are stacked. The temperature of the Epstein test pieces is measured using thermocouples.

[0099] In temperature measurement, test Epstein test pieces and an equal number of temperature measuring Epstein test pieces are placed in the same heat treatment furnace and heat-treated simultaneously. Specifically, the following is prepared: a test Epstein test piece group consisting of several stacked test Epstein test pieces, and a temperature measuring Epstein test piece group consisting of several stacked temperature measuring Epstein test pieces. The insulating coating of the Epstein test piece (steel plate) positioned at the center of the stacking direction of the temperature measuring Epstein test piece group is removed with sandpaper (#240). A thermocouple is fused to the area where the insulating coating has been removed. The temperature measuring Epstein test piece group with the fused thermocouples and the test Epstein test piece group are heat-treated simultaneously. At this time, the temperature obtained by the thermocouple of the temperature measuring Epstein test piece group is considered the temperature of the test Epstein test piece group.

[0100] Furthermore, during heat treatment, the Epstein test pieces within the test piece assembly do not need to be fixed together, nor do the Epstein test pieces within the temperature measurement piece assembly. In the temperature measurement piece assembly, if the stacking of several temperature measurement Epstein test pieces becomes unstable due to the insertion of thermocouples, the ends of the temperature measurement Epstein test piece assembly along its length can be secured using stainless steel wire of approximately 0.3 mm in diameter.

[0101] Test Epstein strips (L-direction and C-direction strips), heated to 800°C, were placed in an Epstein square. Following the method described in [Method for Determining Iron Loss W5 / 1000 of Non-directional Electromagnetic Steel Sheets], four L-direction strips were placed on each pair of sides parallel to the X-direction of the Epstein square. Four C-direction strips were placed on each pair of sides parallel to the Y-direction. The ends of the L-direction and C-direction strips were stacked in an alternating overlapping manner. This formed a square. The square Epstein strips were then tested according to the electromagnetic steel strip test methods of JIS C 2550-1:2011 and 2550-3:2019, and the iron loss W10 / 400 at 400Hz and 1.0T was measured.

[0102] [The effect of the non-directional electromagnetic steel sheet in this embodiment] The non-directional electromagnetic steel sheet of this embodiment satisfies Features 1 to 5. Therefore, high strength and excellent magnetic flux density can be obtained in the non-directional electromagnetic steel sheet of this embodiment. Furthermore, excellent iron loss can be obtained in the non-directional electromagnetic steel sheet of this embodiment after stress annealing.

[0103] [Regarding strength] In this embodiment of the non-directional electromagnetic steel sheet, even higher strength can be obtained. Specifically, in this embodiment of the non-directional electromagnetic steel sheet, the yield stress is 450 MPa or higher. The appropriate lower limit for yield stress is 460 MPa, more preferably 470 MPa, and even more preferably 480 MPa. The upper limit of the yield stress is not specifically limited. However, in the non-directional electromagnetic steel sheet of this embodiment, the upper limit of the yield stress is, for example, 530 MPa.

[0104] [Methods for measuring yield stress] The yield stress of the non-directional electromagnetic steel sheet in this embodiment is measured by the following method. Tensile test specimens of JIS No. 5 as specified in JIS Z 2241:2011 were taken from non-directional electromagnetic steel sheets. Using the taken tensile test specimens, tensile tests were conducted at room temperature and atmospheric pressure according to JIS Z 2241:2011 to obtain the yield stress (MPa). Regarding the yield stress, if an upper yield point appears in the stress-strain curve obtained through the tensile test, it is defined as the upper yield point (MPa). If no upper yield point appears in the obtained stress-strain curve, it is defined as the 0.2% offset yield strength (MPa).

[0105] [Regarding magnetic flux density] In the non-directional electromagnetic steel sheet of this embodiment, an excellent magnetic flux density can be obtained. Specifically, with the rolling direction as the reference 0°, the magnetic flux density B50 in each angular direction with a spacing of 22.5° is defined as: B50(0°), B50(22.5°), B50(45°), B50(67.5°) and B50(90°). At this time, the average magnetic flux density B50ave defined by equation (5) is 1.65T or more. B50ave=(B50(0°)+2×B50(22.5°)+2×B50(45°)+2×B50(67.5°)+B50(90°)) / 8 (5)

[0106] [Method for determining the average magnetic flux density B50ave] The average magnetic flux density B50ave is obtained by the following method. In non-directional electromagnetic steel sheets, Epstein test pieces were prepared in the rolling direction (L direction), 22.5°, 45°, 67.5° directions (from the rolling direction), and a direction perpendicular to the rolling direction (90° direction, i.e., C direction), and the magnetic flux density B50 in each direction was measured using these pieces. The test method was basically based on JIS C 2550-1 (2011). One set of Epstein test pieces extending in the L, 22.5°, 45°, 67.5°, and C directions was cut out in each direction. For each set of Epstein test pieces cut out in the same direction, the electromagnetic steel strip test method according to JIS C 2550-1 (2011) and 2550-3 (2011) was performed, and the magnetic flux density B50 in each direction at 5000 A / m was measured. Substituting the obtained magnetic flux density B50 in each direction into equation (5), the average magnetic flux density B50ave(T) is obtained.

[0107] Suitablely, in the non-directional electromagnetic steel sheet of this embodiment, after the non-directional electromagnetic steel sheet is heat-treated at 800° for 1 hour, the magnetic flux density B1 in each angular direction with a 22.5° interval is defined as follows when the rolling direction is 0°: B1(0°), B1(22.5°), B1(45°), B1(67.5°) and B1(90°). At this time, the average magnetic flux density B1ave defined by Equation (6) is 0.70T or more. When the direction of the maximum value of magnetic flux density B500 is 0°, the magnetic flux density B500 in each angular direction with a 22.5° interval is defined as follows: B500(0°), B500(22.5°), B500(45°), B500(67.5°) and B500(90°). At this time, the average magnetic flux density B500ave defined by Equation (7) is 1.98T or more. B1ave=(B1(0°)+2×B1(22.5°)+2×B1(45°)+2×B1(67.5°)+B1(90°)) / 8 (6) B500ave=(B500(0°)+2×B500(22.5°)+2×B500(45°)+2×B500(67.5°)+B500(90°)) / 8 (7)

[0108] If the average magnetic flux density B1ave of the non-directional electromagnetic steel sheet after heat treatment at 800°C for 1 hour is 0.70T or more and the average magnetic flux density B500ave is 1.98T or more, then in an electric vehicle, sufficient magnetic flux density can be obtained in any of the following situations: when the magnetic field applied to the motor is at its lowest speed, when the magnetic field applied to the motor is higher than that when driving on the street but lower than that when climbing a hill, and when the magnetic field applied to the motor is at its highest when climbing a hill.

[0109] [Method for determining the average magnetic flux density B1ave] The average magnetic flux density B1ave is obtained by the following method. In non-directional electromagnetic steel sheets, Epstein test pieces were prepared in the rolling direction (L direction), 22.5°, 45°, 67.5° directions (from the rolling direction), and a direction perpendicular to the rolling direction (90° direction, i.e., C direction). The non-directional electromagnetic steel sheets were heat-treated at 800°C for 1 hour (relaxation annealing). Using the heat-treated Epstein test pieces, the magnetic flux density B1 in each direction was measured. The test method was basically based on JIS C 2550-1 (2011). For Epstein test pieces extending in the L, 22.5°, 45°, 67.5°, and C directions, for each group of Epstein test pieces in the same direction, the electromagnetic steel strip test methods according to JIS C 2550-1 (2011) and 2550-3 (2011) were implemented, and the magnetic flux density B1 in each direction at 100 A / m was measured. Substituting the obtained magnetic flux density B1 in each direction into equation (6), the average magnetic flux density B1ave(T) is obtained.

[0110] [Method for measuring average magnetic flux density B500ave] The average magnetic flux density B500ave is obtained by the following method. In non-directional electromagnetic steel sheets, Epstein test pieces were prepared in the rolling direction (L direction), 22.5°, 45°, 67.5° directions (from the rolling direction), and a direction perpendicular to the rolling direction (90° direction, i.e., C direction). The non-directional electromagnetic steel sheets were heat-treated at 800°C for 1 hour (relaxation annealing). Using the heat-treated Epstein test pieces, the magnetic flux density B500 in each direction was measured. The test method was basically based on JIS C 2550-1 (2011). For Epstein test pieces extending in the L, 22.5°, 45°, 67.5°, and C directions, for each group of Epstein test pieces in the same direction, the electromagnetic steel strip test method according to JIS C 2550-1 (2011) and 2550-3 (2011) was implemented, and the magnetic flux density B500 in each direction at 50000 A / m was measured. Substituting the obtained magnetic flux density B500 in each direction into equation (7), the average magnetic flux density B500ave(T) is obtained.

[0111] [Regarding iron loss] In the non-directional electromagnetic steel sheet of this embodiment, excellent iron loss can be obtained after stress annealing. Specifically, the iron loss W10 / 400 of the non-directional electromagnetic steel sheet after heat treatment at 800°C for 1 hour is less than F4W / kg.

[0112] [Regarding other features] [Regarding thermal conductivity] Furthermore, the non-directional electromagnetic steel sheet of this embodiment has a high thermal conductivity. Specifically, the non-directional electromagnetic steel sheet of this embodiment has a thermal conductivity of 20 W / mK or higher at 20°C and a thermal conductivity of 23 W / mK or higher at 150°C.

[0113] At this point, the rotor and stator cores manufactured using the non-directional electromagnetic steel sheet of this embodiment have high thermal conductivity. Therefore, excessive heat accumulation in the motor core can be suppressed during operation. Consequently, demagnetization of the magnets in the motor core can be suppressed.

[0114] [Methods for measuring thermal conductivity] The thermal conductivity of non-directional electromagnetic steel sheets can be determined by the following methods. The thermal conductivity of non-directional electromagnetic steel sheets can be determined by the product of thermal diffusivity, density, and specific heat. Here, the thermal diffusivity, density, and specific heat of non-directional electromagnetic steel sheets are calculated using the following method. The thermal diffusivity of a non-directional electromagnetic steel sheet was determined using a laser flash analyzer. Specifically, a test piece measuring 6 mm φ × sheet thickness was taken from the center of the non-directional electromagnetic steel sheet. One surface of the test piece was irradiated with laser pulses using the laser flash analyzer. Meanwhile, the temperature change on the other surface was detected using an infrared detector. The time-series temperature changes were obtained. The thermal diffusivity (m² / s) was then calculated using the thermal diffusivity equation.

[0115] Furthermore, based on Archimedes' method, the density of the non-directional electromagnetic steel sheet was determined. Specifically, a test piece measuring 100mm × 100mm × sheet thickness was taken from the center of the width of the non-directional electromagnetic steel sheet. The mass of the test piece when dry was determined. Next, the test piece was immersed in a water tank. The mass of the test piece in the immersed state (i.e., under the buoyancy of water) was determined. Using these results and the specific gravity of water, the specific gravity of the test piece (non-directional electromagnetic steel sheet) was determined.

[0116] Furthermore, the specific heat of the non-directional electromagnetic steel sheet was determined using a differential scanning calorimeter. Specifically, a test piece measuring 6 mm in diameter (φ × thickness) was taken from the center of the non-directional electromagnetic steel sheet. The test piece was placed on the sample pan of the differential scanning calorimeter. A substance with a known specific heat was used as a control sample. The temperature of the test piece and the control sample were changed at a certain rate, and the specific heat of the test piece (non-directional electromagnetic steel sheet) was determined based on the difference in temperature changes between the two. Based on the obtained thermal diffusivity, specific gravity, and specific heat of the non-directional electromagnetic steel sheet, the thermal conductivity (W / mK) of the non-directional electromagnetic steel sheet at 20℃ and at 150℃ is calculated.

[0117] [Regarding the tensile strength at break] Furthermore, the non-directional electromagnetic steel sheet of this embodiment exhibits excellent tensile strength at break. Specifically, the non-directional electromagnetic steel sheet of this embodiment has a tensile strength at break of 20% or more. Therefore, when manufacturing a motor core by stacking several motor core materials (rotor core materials or stator core materials described below) obtained from the non-directional electromagnetic steel sheet, the stacked motor core materials can be fixed by bonding without using an adhesive.

[0118] In the non-directional electromagnetic steel sheet of this embodiment, as described above, excellent tensile strength at break can be obtained. Therefore, when manufacturing motor core material using the non-directional electromagnetic steel sheet of this embodiment as material, convergence can be achieved even when the sheet thickness is 0.30 mm or less. In the motor core formed by the accumulation of motor core material layers, excellent iron loss can be obtained.

[0119] Regarding the tensile strength at break, a tensile test can be performed based on the method described above in [Method for Determining Yield Stress], and the result can be calculated based on the obtained stress-strain curve.

[0120] [Manufacturing method of non-directional electromagnetic steel sheet] This section describes one example of a method for manufacturing a non-directional electromagnetic steel sheet according to this embodiment. One example of a method for manufacturing a non-directional electromagnetic steel sheet according to this embodiment includes the following steps. (Step 1) Hot Rolling Step (Step 2) Annealing of hot-rolled sheet (Step 3) Cold rolling process (Step 4) Finishing and annealing steps Furthermore, the hot-rolled plate annealing step in step 2 is optional and can be performed or omitted. The following is a description of each step.

[0121] [(Step 1) Hot Rolling Step] In the hot rolling step, a billet is hot-rolled to produce a hot-rolled steel sheet. The billet has the following characteristics: the chemical composition of the resulting non-directional electromagnetic steel sheet satisfies characteristic 1. The billet can be manufactured by known methods. For example, the billet can be manufactured using molten steel with the above-mentioned chemical composition by continuous casting.

[0122] For the prepared blank, hot rolling is performed. It is suitable that the conditions of the hot rolling step are adjusted according to whether a subsequent hot-rolled sheet annealing step is performed. For example, when the hot-rolled sheet annealing step is not performed (i.e., self-annealing is used), the suitable blank heating temperature in the hot rolling step is 1200°C to 1250°C, the suitable finishing rolling temperature is above 1050°C, and the suitable coiling temperature is below 750°C. For example, when the hot-rolled sheet annealing is performed, the suitable blank heating temperature in the hot rolling step is 1100°C to 1150°C, the suitable finishing rolling temperature is below 850°C, and the suitable coiling temperature is below 700°C.

[0123] [(Step 2) Annealing of hot-rolled sheet] The annealing step for hot-rolled steel sheets is optional. That is, the annealing step for hot-rolled steel sheets may or may not be performed. When performing a hot-rolled sheet annealing step and using box annealing as the annealing process, the suitable heat treatment temperature is 800°C or higher, and the suitable soaking time at the heat treatment temperature is 10 hours or higher. When performing continuous annealing as the annealing process, the suitable heat treatment temperature is 950°C or higher, and the suitable soaking time at the heat treatment temperature is 30 seconds or higher. Furthermore, for the steel sheet before and / or after annealing in the hot-rolled sheet annealing step, known pickling treatments may also be performed as needed.

[0124] [(Step 3) Cold Rolling Step] In the cold rolling step, cold rolling is performed on hot-rolled steel sheets produced in the hot rolling step or hot-rolled steel sheets after the annealing step to produce cold-rolled steel sheets. Cold rolling can be performed once or several times. When performing several cold rolling steps, known intermediate annealing can also be performed after cold rolling and before the next cold rolling step.

[0125] [(Step 4) Finishing and annealing step] For cold-rolled steel sheets produced by the cold rolling process, a finishing annealing process is performed to manufacture non-directional electromagnetic steel sheets. In the finishing annealing process, the cold-rolled steel sheet, finished to its final thickness, is annealed to allow recrystallization and grain growth. The finishing annealing process includes: a heating step, a homogenization step to homogenize the steel sheet at the highest reached temperature T1 (°C), and a cooling step to cool the steel sheet after the homogenization step. Conditions 1 to 3 are satisfied in the finishing annealing process. (Condition 1) Annealing is performed at the highest reaching temperature T1 below 900℃. (Condition 2) The temperature lower between the highest reached temperature T1 (°C) and 800°C is called the highest strain-affected temperature T2 (°C). Furthermore, during the cooling process, the temperature range from the highest strain-affected temperature T2 to 500°C is called the strain-imposed temperature range. During the strain-imposed temperature range in the cooling process, the tension TE (kgf / mm²) applied to the steel plate satisfies the following equation (A). 1.0≧TE≧1.2-T2 / 1000 (A) Here, TE in equation (A) is the tension (kgf / mm2) applied to the steel plate in the strain-imposing temperature region. When the tension changes in the strain-imposing temperature region, the maximum tension in the strain-imposing temperature region is substituted into TE in equation (A). Furthermore, when tension is applied to the steel plate during the cooling process to introduce strain, the strain is easily eliminated due to recovery in the temperature range above 800°C. Therefore, the temperature T2 at which the strain effect reaches its maximum is defined as the lower of the maximum temperature T1 and 800°C. (Condition 3) The highest temperature reached T1, tension TE, strain-affected highest temperature T2, and the average cooling rate CR (°C / sec) from the strain-affected highest temperature T2 to 500°C through the cooling process satisfy Equation (B). LOG{(T2-500) / CR-5}×TE≧0.02 (B) Here, in Equation (B), T2 is the temperature T2 (°C) at which the strain influence is highest. CR is the average cooling rate CR (°C / second). TE is the tension (kgf / mm2) applied to the steel plate in the strain-imposed temperature region. When the tension changes in the strain-imposed temperature region, TE in Equation (B) is the maximum tension in the strain-imposed temperature region. The following is an explanation of each condition.

[0126] [Regarding (Condition 1) the highest reached temperature T1] The maximum temperature reached, T1, is set to below 900℃. If the maximum temperature reached, T1, is greater than 900°C, the strain and strain distribution in the manufactured non-directional electromagnetic steel sheet will not become appropriate. As a result, F3 will be greater than W5 / 1000, or F4 will be less than the iron loss W10 / 400 after heat treatment at 800°C for 1 hour. If the maximum temperature reached, T1, is below 900°C, the strain and strain distribution in the manufactured non-directional electromagnetic steel sheet will become appropriate. As a result, F3 will be below W5 / 1000, and F4 will be above W10 / 400 after heat treatment at 800°C for 1 hour. In addition, the lower limit of the maximum reachable temperature T1 is, for example, 700°C.

[0127] [Regarding Equation (A) of Condition 2] During the cooling process, in the strain temperature region, the tension TE applied to the steel plate is adjusted to satisfy the following equation (A). 1.0≧TE≧1.2-T2 / 1000 (A)

[0128] The tension TE applied to the steel sheet in the strain temperature region affects the strain and strain distribution of the produced non-directional electromagnetic steel sheet.

[0129] The FA is defined as follows. FA = 1.2 - T2 / 1000 If the tension TE (kgf / mm2) is less than FA, the strain and strain distribution imposed on the steel plate in the strain-imposing temperature region will become inappropriate. Therefore, F3 will be greater than W5 / 1000, or F4 will be less than the iron loss W10 / 400 after heat treatment at 800°C for 1 hour. If the tension TE (kgf / mm2) is FA or higher, then the strain and strain distribution imposed on the steel plate in the strain-imposing temperature range will be within the appropriate range. Therefore, F3 will be W5 / 1000 or lower, and F4 will be W10 / 400 or higher after heat treatment at 800°C for 1 hour.

[0130] On the other hand, if the tension TE is greater than 1.0 kgf / mm², excessive strain will be introduced in the strain-imposed temperature region, resulting in a large amount of pair annihilation. In this case, the strain will be insufficient, and an appropriate strain distribution cannot be formed. Therefore, F3 will be greater than W5 / 1000, or F4 will be less than the iron loss W10 / 400 after heat treatment at 800°C for 1 hour.

[0131] [Regarding equation (B) of condition 3] To introduce a suitable amount of strain and form a suitable strain distribution in a non-directional electromagnetic steel sheet, a suitable tension TE must be applied for a suitable time within the strain-imposing temperature region. Here, RS is defined as follows. RS=LOG{(T2-500) / CR-5}×TE≧0.02 (B) Here, in Equation (B), T2 is substituted into the temperature T2 (°C) where the strain influence is highest. CR is substituted into the average cooling rate CR (°C / sec). TE is substituted into the tension (kgf / mm2) imposed on the steel plate in the strain-imposing temperature region.

[0132] When RS is less than 0.02, the tension application time for condition 2 is too short in the strain application temperature range. At this time, the strain accumulated in the non-directional electromagnetic steel sheet is insufficient to form a suitable strain distribution. Therefore, F3 will be greater than W5 / 1000, or F4 will be less than the iron loss W10 / 400 after heat treatment at 800℃ for 1 hour. If RS is above 0.02, then, assuming other conditions are met, the strain accumulated in the non-directional electromagnetic steel sheet is appropriate and will form an appropriate strain distribution. As a result, F3 will be below W5 / 1000, and F4 will be above W10 / 400 after heat treatment at 800℃ for 1 hour.

[0133] [Other steps] In the above manufacturing method, a coating step can also be performed after the finishing annealing step. In the coating step, an insulating coating is applied to the surface of the non-directional electromagnetic steel sheet after finishing annealing. The type of insulating coating is not particularly limited. The insulating coating can be organic, inorganic, or a mixture of organic and inorganic components.

[0134] The non-directional electromagnetic steel sheet of this embodiment can be manufactured using the above manufacturing method. In addition, if the non-directional electromagnetic steel sheet of this embodiment satisfies features 1 to 5, the manufacturing method is not particularly limited.

[0135] [About the rotor core] The rotor core of this embodiment is manufactured using the non-directional electromagnetic steel plate of this embodiment as the material. Figure 1A is a plan view showing an example of a rotor core 1. Referring to Figure 1A, the rotor core 1 includes: a plurality of rotor core materials 10. The rotor core materials 10 are plate-shaped. The rotor core 1 is composed of layers of a plurality of rotor core materials 10.

[0136] The shape of the rotor core is not particularly limited if it is plate-shaped. Figure 1A shows an example of a rotor core for a permanent magnet synchronous motor. In Figure 1A, the rotor core material 10 is a circular plate and contains several through holes 11 arranged in the circumferential direction. Permanent magnets (not shown) can be placed in the through holes 11. The rotor core material 10 also includes a through hole 13 in the center. A motor shaft (not shown) can be inserted into the through hole 13.

[0137] Furthermore, although Figure 1A shows the rotor core of a permanent magnet synchronous motor, it can also be other shapes if the rotor core is plate-shaped. For example, when the motor is a reluctance motor, the rotor core can be plate-shaped with several protruding poles 15 as shown in Figure 1B, or it can be circular plate-shaped with several through holes 16 that can form a flux barrier as shown in Figure 1C. Also, when the motor is an induction motor, the rotor core can also have several through holes, and these through holes are provided with paths for induced current to pass through copper or aluminum die-cast parts, etc.

[0138] Regarding the rotor core material 10, it can be manufactured by punching a non-directional electromagnetic steel sheet of this embodiment. Therefore, the rotor core material 10 will satisfy characteristics 1 to 5. Therefore, the rotor core 1 has high strength. The rotor core 1 also has excellent magnetic flux density. The rotor core material 10 has excellent tensile strength at break. Specifically, the tensile strength at break of the rotor core material 10 is 20% or more.

[0139] [Methods for Determining the Magnetic Properties of Rotor Core Materials] The magnetic flux density and iron loss of the rotor core material can be determined based on the Single Sheet Tester (SST) specified in JIS C 2556:2015.

[0140] Specifically, the rotor core material is separated from the rotor core. If the rotor core materials are fixed together by an adhesive, the rotor core materials can also be heated to a temperature range of 300~450°C to soften the adhesive before separating the rotor core materials from the rotor core.

[0141] SST test pieces are taken from the separated rotor core material. Furthermore, wire cutting is used to obtain the SST test pieces to avoid processing strain. The SST test pieces are, for example, 55mm × 55mm × plate thickness.

[0142] Additionally, when it is not possible to obtain 55mm × 55mm × plate thickness SST test pieces from the rotor core material, two L-direction (rolling direction) SST test pieces measuring 16mm × 8mm × plate thickness are used, and two C-direction (perpendicular to the rolling direction) SST test pieces measuring 16mm × 8mm × plate thickness are used. In the L-direction iron loss measurement, the two L-direction SST test pieces are arranged in a 16mm × 16mm square for the test. In the C-direction iron loss measurement, the two C-direction SST test pieces are arranged in a 16mm × 16mm square for the test.

[0143] Using the SST test piece and through the above-mentioned single-plate magnetic property test (SST test), the iron loss W5 / 1000 (L) (W / kg) in the L direction and the iron loss W5 / 1000 (C) (W / kg) in the C direction are determined. The arithmetic mean of the iron loss W5 / 1000 (L) (W / kg) in the L direction and the iron loss W5 / 1000 (C) (W / kg) in the C direction is defined as the iron loss W5 / 1000(L+C) (W / kg). The obtained iron loss W5 / 1000(L+C) is converted into the measured value in the Epstein test apparatus specified in JIS C 2550-1:2011 and JIS C 2550-3:2019, and is taken as the Epstein equivalent value.

[0144] The Epstein equivalent value can be obtained by the following method. Epstein test pieces and SST test pieces are taken from the same non-directional electromagnetic steel sheet. For the Epstein test piece, the iron loss W5 / 1000 (EP) (W / kg) is determined using the method described above in [Method for Determining Iron Loss W5 / 1000 of Non-directional Electromagnetic Steel Sheets]. For the SST test piece, the above SST test is performed, and the iron loss W5 / 1000 (L+C) (W / kg) is determined. Based on the obtained iron loss W5 / 1000 (EP) (W / kg) in the Epstein test piece and the iron loss W5 / 1000 (L+C) (W / kg) in the SST test piece, the conversion factor K is calculated using the following formula. K = (Iron loss W5 / 1000(EP) in the Epstein test piece) / (Iron loss W5 / 1000(L+C) in the SST test piece)

[0145] The measured value of the rotor core obtained from the SST test (iron loss W5 / 1000(L+C)) is multiplied by the above K to calculate the Epstein equivalent value of iron loss W5 / 1000 (W / kg). This Epstein equivalent value is defined as the rotor core iron loss W5 / 1000 (W / kg).

[0146] In addition, when it is not possible to obtain Epstein test pieces from the rotor core material, a non-directional electromagnetic steel plate is prepared, the density, magnetic flux density B50, and iron loss W5 / 1000(L+C) of which are substantially equivalent to the density of the rotor core material, the magnetic flux density B50 in the SST test, and the iron loss W5 / 1000(L+C). Specifically, in the prepared non-directional electromagnetic steel plate, the density is defined as: within ±1% of the density of the rotor core material; the iron loss W5 / 1000(L+C) obtained from the SST test piece is defined as: within ±5% of the iron loss W5 / 1000(L+C) obtained from the SST test piece of the rotor core material; and the magnetic flux density B50 obtained from the SST test piece is defined as: within ±2% of the magnetic flux density B50 obtained from the SST test piece of the rotor core material. Using the prepared non-directional electromagnetic steel sheet and following the method described in "[Method for Determining Iron Loss W5 / 1000 of Non-directional Electromagnetic Steel Sheet]", the iron loss W5 / 1000 (EP) was determined using an Epstein test piece. The obtained iron loss W5 / 1000 (EP) (W / kg) was defined as the Epstein equivalent value.

[0147] Suitablely, as shown in Figures 1A-1C, the rotor core material 10 may also include a convergent portion 12 and a flat portion 14. The convergent portion 12 is a recess formed in the rotor core material 10. When several rotor core materials 10 are stacked, the convergent portions 12 of the stacked rotor core materials 10 will interlock and fix each other. The flat portion 14 is different from the convergent portion 12 and is a flat area. The flat portion 14 is the part that forms the base material of the rotor core material 10, and the thickness of the flat portion 14 is equivalent to the thickness of the non-directional electromagnetic steel plate used as the material.

[0148] When the rotor core 1 is formed using the convergence portion 12, it is not necessary to use an adhesive to fix the rotor core materials 10 together. When the rotor core materials 10 are fixed together using an adhesive, the volume shrinkage during adhesive solidification will cause compressive stress on the rotor core materials 10. The iron loss of the rotor core 1 will deteriorate due to this compressive stress. On the other hand, when the convergence portion 12 is used to fix the rotor core materials 10 together, no compressive stress as with an adhesive is imposed.

[0149] Figure 2A is a cross-sectional view of line segment IIA-IIA (X direction) of the convergence portion 12 in Figure 1A. Figure 2B is a cross-sectional view of line segment IIB-IIB (Y direction) of the convergence portion 12 in Figure 1A. Referring to Figures 2A and 2B, the convergence portion 12 includes a pair of inclined portions 121. The inclined portions 121 are formed inclined relative to the flat portion 14 of the rotor core material 10. The convergence portion 12 may also include a bottom 122 between the pair of inclined portions 121. Alternatively, the convergence portion 12 may not include a bottom 122, but the lower ends of the pair of inclined portions 121 are connected to each other, which is called V-convergence. The presence of inclined portions 121 in the convergence portion 12 increases the fixing force brought about by the engagement.

[0150] Furthermore, the cross-sectional shape of the convergent portion 12 is not limited to the shape shown in Figure 2B or the V-shaped convergence. For example, it can be U-shaped or W-shaped. The convergent portion 12 can also be N-shaped. If the convergent portion 12 contains an inclined portion 121, the cross-sectional shape of the convergent portion 12 is not particularly limited.

[0151] The inclined portion 121 of the convergent portion 12 corresponds to the thinnest part of the rotor core material 10. The plate thickness PT121 of the inclined portion 121 is less than 85% of the plate thickness PT14 of the flat portion 14 of the rotor core material 10. In addition, the plate thickness PT14 of the flat portion 14 is equivalent to the plate thickness t of the non-directional electromagnetic steel plate used as material.

[0152] As described above, in this embodiment, the plate thickness PT121 of the inclined portion 121 of the convergent portion 12 is thinner than the plate thickness PT14 of the flat portion 14. Therefore, the inclination angle of the inclined portion 121 relative to the flat portion 14 can be made steeper. As a result, the size of the inclined portion 12 when viewed from above the rotor core material 10 can be kept small. Furthermore, the steep inclination angle of the inclined portion 121 relative to the flat portion 14 increases the fixing force during engagement.

[0153] When forming the convergent portion 12 containing the inclined portion 121, the plate thickness of the inclined portion 121 becomes thinner. Therefore, the rotor core material 10 must have sufficient ductility to form the inclined portion 121. As described above, the rotor core material 10, satisfying characteristics 1 to 5, exhibits excellent tensile strength at break. Thus, a convergent portion 12 can be formed in which the plate thickness PT121 of the inclined portion 121 is 85% or less of the plate thickness PT14 of the flat portion 14.

[0154] Preferably, the thickness PT121 of the inclined portion 121 is 83% or less, more preferably 80% or less, of the thickness PT14 of the flat portion 14. Preferably, the thickness PT121 is 50% or more, more preferably 60% or more, and more preferably 70% or more.

[0155] Suitable for the rotor core material 10, the flat portion 14 has a Vickers hardness H14 of 180 HV or higher at the center of the plate thickness. The inclined portion 121 of the convergent portion 12 of the rotor core material 10 has a Vickers hardness H121 of H14+40 HV or higher at the center of the plate thickness. As described above, the rotor core material 10 satisfies properties 1 to 5. Therefore, it has excellent strength. As a result, the Vickers hardness of the convergent portion 12 and the Vickers hardness of the flat portion 14 also increase.

[0156] [Methods for measuring the thickness PT14 of the flat portion 14 and the thickness PT121 of the inclined portion 121] The plate thickness PT14 of the flat portion 14 and the plate thickness PT121 of the inclined portion 121 are determined by the following method: A test piece covering the cross-section shown in Figure 2B is taken from one rotor core material 10. The plate thickness of the flat portion 14 is measured at any five locations, and the arithmetic mean of the five obtained values ​​is taken as the plate thickness PT14 (mm) of the flat portion 14. The plate thickness PT14 (mm) is a value rounded to the third decimal place, which is obtained by rounding the fourth decimal place of the obtained arithmetic mean. Further, the plate thickness is measured at any five locations of the inclined portion 121, and the arithmetic mean of the five obtained values ​​is taken as the plate thickness PT121 (mm) of the inclined portion 121. The plate thickness PT121 (mm) is a value rounded to the third decimal place, which is obtained by rounding the fourth decimal place of the obtained arithmetic mean. The measurement can be performed using a micrometer or a non-contact measuring device such as a plate thickness measuring instrument using laser triangulation.

[0157] [Methods for determining the Vickers hardness H14 of the flat portion 14 and the Vickers hardness H121 of the inclined portion 121] The Vickers hardness H14 of the flat portion 14 and the Vickers hardness H121 of the inclined portion 121 are determined by the following method. A test piece covering the cross-section shown in Figure 2B is taken from the rotor core material 10. At five locations at the center of any thickness of the inclined portion 121 within this cross-section, a Vickers hardness test prepared according to JIS Z 2244-1:2020 is performed. The test force is set to 1 N. Alternatively, if the Vickers hardness testing machine can only control the test force in kgf units, the test force is set to 0.1 kgf. The arithmetic mean of the obtained Vickers hardness is defined as the Vickers hardness H121 (HV) of the inclined portion 121. The Vickers hardness H121 (HV) is defined as the integer value obtained by rounding the first decimal place of the obtained arithmetic mean.

[0158] Similarly, in this cross-section of the test piece, at five locations at the center of any thickness of the flat portion 14, a Vickers hardness test prepared according to JIS Z 2244-1:2020 is performed. The test force is set to 1 N. Alternatively, if the Vickers hardness testing machine can only control the test force in kgf units, the test force is set to 0.1 kgf. The arithmetic mean of the obtained Vickers hardness is defined as the Vickers hardness (HV) of the flat portion 14, which is H14. The Vickers hardness H14 (HV) is defined as the integer value obtained by rounding the first decimal place of the obtained arithmetic mean.

[0159] [About the stator core] The stator core of this embodiment is manufactured using the non-directional electromagnetic steel plate of this embodiment as the material. Figure 3 is a plan view of the stator core 2. Referring to Figure 3, the stator core 2 comprises several stator core materials 20. The stator core materials 20 are in the shape of circular ring plates. The stator core 2 is composed of layers of several stator core materials 20. The stator core material 20 includes a plurality of teeth 21. The plurality of teeth 21 are arranged with gaps in the circumferential direction of the stator core material 20. Then, the teeth 21 extend in the radial direction of the stator core material 20.

[0160] Regarding the stator core material 20, it can be manufactured by punching and then subjecting the non-directional electromagnetic steel sheet of this embodiment to stress annealing. Therefore, the stator core material 20 will satisfy characteristics 1 to 4, and further, F4 as defined in equation (4) is an iron loss W10 / 400 or higher. Therefore, the stator core 2 has excellent magnetic flux density and excellent iron loss. Even before stress annealing and after punching, the stator core material 20 has an excellent tensile strength at break, just like the rotor core material 10. Specifically, the tensile strength at break of the stator core material 20 is 20% or higher.

[0161] [Methods for Determining the Magnetic Properties of Stator Core Materials] The magnetic flux density and iron loss of the stator core material can be determined based on the Single Sheet Tester (SST) specified in JIS C 2556:2015. Specifically, the stator core material is separated from the stator core. If the stator core materials are fixed together by an adhesive, the stator core materials can also be heated to a temperature range of 300~450°C to soften the adhesive before separating the stator materials from the stator core. SST test pieces were taken from the separated stator core material. Furthermore, wire cutting was used to obtain the SST test pieces to avoid processing strain. The SST test pieces were, for example, 55mm × 55mm × plate thickness.

[0162] Additionally, when it is not possible to obtain a 55mm × 55mm × plate thickness SST test piece from the stator core material, two L-direction (rolling direction) SST test pieces measuring 16mm × 8mm × plate thickness are used, and two C-direction (perpendicular to the rolling direction) SST test pieces measuring 16mm × 8mm × plate thickness are used. In the L-direction iron loss measurement, the two L-direction SST test pieces are arranged in a 16mm × 16mm square for the test. In the C-direction iron loss measurement, the two C-direction SST test pieces are arranged in a 16mm × 16mm square for the test.

[0163] Using the SST test piece and through the above-mentioned single-plate magnetic property test (SST test), the iron loss W5 / 1000(L)(W / kg) in the L direction and the iron loss W5 / 1000(C)(W / kg) in the C direction are determined. The arithmetic mean of the iron loss W5 / 1000(L)(W / kg) in the L direction and the iron loss W5 / 1000(C)(W / kg) in the C direction is defined as the iron loss W5 / 1000(L+C)(W / kg). The obtained iron loss W5 / 1000(L+C) is converted into the measured value in the Epstein test apparatus specified in JIS C 2550-1:2011 and JIS C 2550-3:2019, and is taken as the Epstein equivalent value.

[0164] The Epstein equivalent value can be obtained by the following method. Epstein test pieces and SST test pieces are taken from the same non-directional electromagnetic steel sheet. For the Epstein test piece, the iron loss W5 / 1000 (EP) (W / kg) is determined using the method described above in [Method for Determining Iron Loss W5 / 1000 of Non-directional Electromagnetic Steel Sheets]. For the SST test piece, the above SST test is performed, and the iron loss W5 / 1000 (L+C) (W / kg) is determined. Based on the obtained iron loss W5 / 1000 (EP) (W / kg) in the Epstein test piece and the iron loss W5 / 1000 (L+C) (W / kg) in the SST test piece, the conversion factor K is calculated using the following formula. K = (Iron loss W5 / 1000(EP) in the Epstein test piece) / (Iron loss W5 / 1000(L+C) in the SST test piece)

[0165] The iron loss W5 / 1000 (W / kg) of the stator obtained from the SST test is multiplied by the aforementioned K to calculate the Epstein equivalent value. This Epstein equivalent value is defined as the iron loss W5 / 1000 (W / kg) of the stator core.

[0166] In addition, when it is not possible to obtain Epstein test pieces from the stator core material, a non-directional electromagnetic steel plate is prepared, the density, magnetic flux density B50, and iron loss W5 / 1000(L+C) of which are substantially equivalent to the density of the stator core material, the magnetic flux density B50 in the SST test, and the iron loss W5 / 1000(L+C). Specifically, in the prepared non-directional electromagnetic steel plate, the density is defined as: within ±1% of the density of the rotor core material; the iron loss W5 / 1000(L+C) obtained from the SST test piece is defined as: within ±5% of the iron loss W5 / 1000(L+C) obtained from the SST test piece of the rotor core material; and the magnetic flux density B50 obtained from the SST test piece is defined as: within ±2% of the magnetic flux density B50 obtained from the SST test piece of the rotor core material. Using the prepared non-directional electromagnetic steel sheet and following the method described in "[Method for Determining Iron Loss W5 / 1000 of Non-directional Electromagnetic Steel Sheet]", the iron loss W5 / 1000 (EP) was determined using an Epstein test piece. The obtained iron loss W5 / 1000 (EP) (W / kg) was defined as the Epstein equivalent value.

[0167] Suitablely, as shown in Figure 3, the stator core material 20 may also include a flat portion 24 and a convergent portion 22. The convergent portion 22 is a recess formed in the stator core material 20. When several stator core materials 20 are stacked, the convergent portions 22 of the stacked stator core materials 20 will interlock and fix each other. That is, the convergent portion 22 plays the same role as the convergent portion 12. The flat portion 24 is different from the convergent portion 22 and is a flat area. The flat portion 24 is the part that forms the base material of the stator core material 20, and the thickness of the flat portion 24 is equivalent to the thickness of the non-directional electromagnetic steel plate used as the material.

[0168] When the stator core 2 is formed using the convergence portion 22, it is not necessary to use an adhesive to fix the stator core materials 20 together. Therefore, when using the convergence portion 22 to fix the stator core materials 20 together, no compressive stress as with an adhesive is introduced. In the case of the stator core 2, after fixing several stator core materials 20 with the convergence portion 22, further stress-relaxation annealing is performed. Therefore, the strain introduced into the convergence portion 22 during its formation is also removed. As a result, in the stator core 2, not only is no compressive stress as with adhesive not introduced, but the strain effect during the formation of the convergence portion 22 is also sufficiently suppressed. Therefore, the stator core 2 has excellent iron loss.

[0169] The configuration of the convergence portion 22 is the same as that of the convergence portion 12. Referring to Figures 2A and 2B, the convergence portion 22 includes a pair of inclined portions 221. The inclined portions 221 are formed by tilting relative to the portion of the stator core material 20 other than the convergence portion 22. The convergence portion 22 may also include a bottom 222 between the pair of inclined portions 221. Alternatively, the convergence portion 22 may not include a bottom 222, in which case the lower ends of the pair of inclined portions 221 are connected, which is called V-convexity. The presence of inclined portions 221 in the convergence portion 22 increases the fixing force brought about by the engagement.

[0170] Furthermore, the converging portion 22, like the converging portion 12, can be U-shaped or W-shaped. The converging portion 22 can also be N-shaped. If the converging portion 22 contains an inclined portion 221, the cross-sectional shape of the converging portion 22 is not particularly limited.

[0171] The inclined portion 221 of the convergent portion 22 corresponds to the thinnest part of the stator core material 20. The plate thickness PT221 of the inclined portion 221 is less than 85% of the plate thickness PT24 of the flat portion 24, which is the portion of the stator core material 20 excluding the convergent portion 22. Furthermore, the plate thickness PT24 of the flat portion 24 corresponds to the plate thickness t of the non-directional electromagnetic steel plate used as the material.

[0172] As described above, in this embodiment, the plate thickness PT221 of the inclined portion 221 of the convergent portion 22 is thinner than the plate thickness PT24 of the flat portion 24. Therefore, the inclination angle of the inclined portion 221 relative to the flat portion 24 can be made steeper. As a result, the size of the inclined portion 22 when viewed from above the stator core material 20 can be kept small. Furthermore, the steep inclination angle of the inclined portion 221 relative to the flat portion 24 increases the fixing force during engagement.

[0173] When forming the convergent portion 22 containing the inclined portion 221, the plate thickness of the inclined portion 221 becomes thinner. Accordingly, the stator core material 20 must have ductility sufficient to form the inclined portion 221. As described above, the stator core material 20 satisfies features 1 to 4, and further, F4 as defined in equation (4) is an iron loss W10 / 400 or higher. Therefore, the tensile strength at break is excellent. Thus, a convergent portion 22 can be formed in which the plate thickness PT221 of the inclined portion 221 is less than 85% of the plate thickness PT24 of the flat portion 24.

[0174] Preferably, the thickness PT221 of the inclined portion 221 is 83% or less, more preferably 80% or less, of the thickness PT24 of the flat portion 24. Preferably, the thickness PT221 is 50% or more, more preferably 60% or more, and more preferably 70% or more.

[0175] Suitable for the stator core material 20, the flat portion 24 at the center of the plate thickness has a Vickers hardness H24 of 175 Hv or higher, and the inclined portion 221 of the converging portion 22 at the center of the plate thickness has a Vickers hardness H221 of less than or equal to the flat portion 24's Vickers hardness H24 ± 10 Hv. Because the stator core material 20 undergoes stress-relaxation annealing, strain is eliminated, resulting in lower hardness.

[0176] [Methods for measuring the thickness PT24 of the flat portion 24 and the thickness PT221 of the inclined portion 221] The plate thickness PT24 of the flat portion 24 and the plate thickness PT221 of the inclined portion 221 are determined by the following method: A test piece covering the cross-section shown in Figure 2B is taken from one rotor core material 10. The plate thickness of the flat portion 24 is measured at any five locations, and the arithmetic mean of the five obtained values ​​is taken as the plate thickness PT24 (mm) of the flat portion 24. The plate thickness PT24 (mm) is an integer value obtained by rounding the first decimal place of the obtained arithmetic mean. Further, the plate thickness is measured at any five locations of the inclined portion 221, and the arithmetic mean of the five obtained values ​​is taken as the plate thickness PT221 (mm) of the inclined portion 221. The plate thickness PT221 (mm) is an integer value obtained by rounding the first decimal place of the obtained arithmetic mean. Measurements can be taken using a micrometer or a non-contact measuring device such as a plate thickness measuring instrument using the laser triangulation method.

[0177] [Methods for determining the Vickers hardness H24 of the flat portion 24 and the Vickers hardness H221 of the inclined portion 221] The Vickers hardness H24 of the flat portion 24 and the Vickers hardness H221 of the inclined portion 221 are determined by the following method: A test piece covering the cross-section shown in Figure 2B is taken from the stator core material 20. At five locations at the center of any thickness of the inclined portion 221 within this cross-section, a Vickers hardness test prepared according to JIS Z 2244-1:2020 is performed. The test force is set to 1 N. Alternatively, if the Vickers hardness testing machine can only control the test force in kgf units, the test force is set to 0.1 kgf. The arithmetic mean of the obtained Vickers hardness is defined as the Vickers hardness H221 (HV) of the inclined portion 221. The Vickers hardness H221 (HV) is the integer value obtained by rounding the first decimal place of the obtained arithmetic mean.

[0178] Similarly, in this cross-section of the test piece, at five locations at the center of any thickness of the flat portion 24, a Vickers hardness test prepared according to JIS Z 2244-1:2020 was performed. The test force was set to 1 N. The arithmetic mean of the obtained Vickers hardness was defined as the Vickers hardness H24 (HV) of the flat portion 24. The Vickers hardness H24 (HV) is defined as the integer value obtained by rounding the first decimal place of the obtained arithmetic mean.

[0179] [Manufacturing method of rotor core 1 and stator core 2] The rotor core 1 and stator core 2 are manufactured by the following method. From the non-directional electromagnetic steel sheet of this embodiment, rotor core material 10 and stator core material 20 are manufactured by punching. Before performing the punching process, a convergent portion 12 is formed in the area that will become rotor core material 10 by pressing. Similarly, a convergent portion 22 is formed in the area that will become stator core material 20 by pressing.

[0180] After the convergence portion 12 is formed, the rotor core material 10 is continuously punched. At this time, newly punched rotor core material 10 is stacked on the punched rotor core material 10, and the convergence portions 12 are interlocked. That is, the stacking and interlocking operations of the rotor core material 10 are performed simultaneously with the punching process. The rotor core 1 is manufactured through the above steps.

[0181] Similarly, after the convergence portion 22 is formed, the stator core material 20 is continuously punched. At this time, newly punched stator core material 20 is stacked on the punched stator core material 20, and the convergence portions 22 are interlocked. That is, the stacking and interlocking operations of the stator core material 20 are performed simultaneously with the punching process. For the stacked stator core materials 20, a relaxation annealing process is performed. This relaxation annealing is, for example, carried out at 800-850°C for 1-10 hours. The stator core 2 is manufactured through these steps.

[0182] [About the motor] The motor of this embodiment includes the aforementioned rotor core and stator core. Because the motor of this embodiment includes the rotor core and stator core of this embodiment, high strength can be obtained in the rotor core. Furthermore, the motor of this embodiment achieves excellent magnetic flux density and iron loss. [Example 1]

[0183] Non-directional electromagnetic steel sheets with the chemical compositions shown in Table 1 (Table 1A, Table 1B, and Table 1C) are manufactured by the following method.

[0184] [Table 1A]

[0185] [Table 1B]

[0186] [Table 1C]

[0187] Hot rolling is performed on flat billets (steel sheets) to produce hot-rolled steel sheets with a thickness of 2.0 mm. The billet heating temperature is 1100℃~1150℃. The finishing rolling temperature is above 800℃ and below 850℃. The coiling temperature is below 700℃. For the hot-rolled steel sheets, hot-rolled annealing is performed at 1000℃ for 1 minute. The annealed hot-rolled steel sheets are then cold-rolled to produce cold-rolled steel sheets of various thicknesses.

[0188] The produced cold-rolled steel sheets are subjected to finishing annealing. The highest temperature reached T1 (°C), tension TE (kgf / mm2), average cooling rate CR (°C / sec), and RS during finishing annealing are listed in Table 2. Additionally, in the column "1.0 ≧ TE ≧ FA" in Table 2, "T" indicates that equation (A) is satisfied, and "F" indicates that equation (A) is not satisfied. Through the above manufacturing steps, non-directional electromagnetic steel sheets for each test number were manufactured. The sheet thickness (mm) for each test number is listed in the "Sheet Thickness t (mm)" column of Table 2. Furthermore, test numbers F1 to F4 are listed in the "F1", "F2", "F3", and "F4" columns of Table 2, respectively. In Table 2, in the "F3≦W5 / 1000" column, "T" means: F3 has an iron loss W5 / 1000 or less. "F" means: F3 has an iron loss greater than W5 / 1000. In the "W10 / 400≦F4" column, "T" means: F4 has a W10 / 400 or greater after heat treatment at 800°C for 1 hour. "F" means: F4 has a W10 / 400 less than after heat treatment at 800°C for 1 hour.

[0189] [Table 2]

[0190] [Evaluation Test] For the non-directional electromagnetic steel plates of each test number, the following evaluation tests were conducted. (Experiment 1) Chemical Composition Determination Experiment (Experiment 2) Plate Thickness Measurement Test (Experiment 3) Iron Loss Measurement Test (Experiment 4) Test for determination of yield stress and tensile strength at break (Experiment 5) Magnetic Flux Density Measurement Experiment (Experiment 6) Thermal conductivity measurement test The following describes Experiments 1 through 6.

[0191] [(Experiment 1) Chemical Composition Determination Test] Based on the method described above in "[Method for Determining the Chemical Composition of Non-directional Electromagnetic Steel Sheets]", the chemical composition of non-directional electromagnetic steel sheets for each test number was measured. The results are shown in Table 1.

[0192] [(Experiment 2) Plate Thickness Measurement Test] Based on the method described above in "[Method for Determining the Thickness t of Non-directional Electromagnetic Steel Sheets]", the thickness of the non-directional electromagnetic steel sheets for each test number was measured. The measurement results are listed in the "Thickness t (mm)" column of Table 2.

[0193] [(Experiment 3) Iron Loss Measurement Test] Based on the above method for determining the iron loss W5 / 1000 of non-directional electromagnetic steel sheets, the iron loss W5 / 1000 (W / kg) of each test number of the non-directional electromagnetic steel sheet was calculated. The obtained iron loss W5 / 1000 is listed in the "Iron Loss W5 / 1000 (W / kg)" column of Table 3. Based on the above method for determining the iron loss W10 / 400 of non-directional electromagnetic steel sheets after relaxation annealing, the iron loss W10 / 400 at a frequency of 400 Hz and a magnetic flux density of 1.0 T after heat treatment at 800℃ for 1 hour was calculated for each test number of non-directional electromagnetic steel sheet. The obtained iron loss W10 / 400 is listed in the "Iron loss W10 / 400 (W / kg) after relaxation annealing" column of Table 3.

[0194] [Table 3]

[0195] [(Experiment 4) Test for determination of yield stress and tensile strength at break] Based on the above-described method for determining yield stress, the yield stress (MPa) of the non-directional electromagnetic steel sheet for each test number was calculated. The obtained yield stresses are listed in the "Yield Stress (MPa)" column of Table 3. Furthermore, from the stress-strain curves obtained from the method for determining yield stress, the tensile strength at break (%) of the non-directional electromagnetic steel sheet for each test number was calculated. The obtained tensile strength at break is listed in the "Tensile Strength at Break (%)" column of Table 3.

[0196] [(Experiment 5) Magnetic Flux Density Measurement Experiment] Based on the above [method for determining the average magnetic flux density B50ave], the average magnetic flux density B50ave(T) of the non-directional electromagnetic steel plate for each test number was obtained. The obtained average magnetic flux density B50ave(T) is listed in the "B50ave(T)" column of Table 3. Based on the above [method for measuring average magnetic flux density B1ave], the average magnetic flux density B1ave(T) of the non-directional electromagnetic steel plate for each test number was obtained. The obtained average magnetic flux density B1ave(T) is listed in the "B1ave(T)" column of Table 3. Based on the above-mentioned method for measuring the average magnetic flux density B500ave, the average magnetic flux density B500ave(T) of the non-directional electromagnetic steel plate for each test number was obtained. The obtained average magnetic flux density B500ave(T) is listed in the "B500ave(T)" column of Table 3.

[0197] [(Experiment 6) Thermal conductivity measurement test] Based on the above [method for determining thermal conductivity], the thermal conductivity (W / mK) at 20℃ and at 150℃ for each test number of the non-directional electromagnetic steel plate was determined. The obtained thermal conductivity at 20℃ and 150℃ are listed in the "20℃ thermal conductivity (W / mK)" and "150℃ thermal conductivity (W / mK)" columns of Table 3.

[0198] [Evaluation Results] Referring to Tables 1-3, test numbers 1-29 satisfy characteristics 1-5. Therefore, a high strength is obtained with a yield strength of 450 MPa or higher. Furthermore, an excellent magnetic flux density is obtained with an average magnetic flux density B50ave of 1.65 T or higher. Furthermore, the iron loss W10 / 400 after relaxation annealing is less than F4W / kg, indicating excellent iron loss after relaxation annealing.

[0199] Furthermore, in these tests numbered 1 to 29, the average magnetic flux density B1ave after relaxation annealing was 0.70 T or higher, and the average magnetic flux density B500ave was 1.98 T or higher. Furthermore, the thermal conductivity at 20°C was 20 W / mK or higher, and the thermal conductivity at 150°C was 23 W / mK or higher, achieving excellent thermal conductivity.

[0200] On the other hand, in tests 30 and 31, F1 does not satisfy equation (1). Therefore, sufficient iron loss cannot be obtained after stress annealing.

[0201] In experiments 32 and 33, F2 does not satisfy equation (2). Therefore, a sufficient magnetic flux density cannot be obtained. Furthermore, in experiment 33, the thermal conductivity is low at 20°C and 150°C. This can be attributed to the high F1.

[0202] In tests 34 and 35, the highest temperature reached during the finishing annealing step, T1, exceeded 900°C. Therefore, F3 exceeded W5 / 1000. Consequently, sufficient yield strength and sufficient tensile strength at break could not be obtained.

[0203] In experiments 36 and 37, the tension TE during the finishing annealing step was less than FA. Therefore, F3 did not satisfy equation (3) and F4 did not satisfy equation (4). As a result, sufficient yield strength could not be obtained. Furthermore, the average magnetic flux density B1ave after relaxation annealing was less than 0.70T, and sufficient magnetic flux density could not be obtained.

[0204] In experiments 38 and 39, the tension TE during the finishing annealing step was greater than 1.0 kgf / mm². Therefore, F3 does not satisfy equation (3) and F4 does not satisfy equation (4). As a result, sufficient yield strength cannot be obtained. Furthermore, the average magnetic flux density B1ave after relaxation annealing is less than 0.70 T, and sufficient magnetic flux density cannot be obtained.

[0205] In tests 40 and 41, RS does not satisfy equation (B). Therefore, F3 does not satisfy equation (3) and F4 does not satisfy equation (4). As a result, sufficient yield strength cannot be obtained. Furthermore, the average magnetic flux density B1ave after relaxation annealing is less than 0.70T, and sufficient magnetic flux density cannot be obtained. [Example 2]

[0206] Using the non-directional electromagnetic steel sheets of each test number in Table 1, rotor core materials of the shape shown in Figure 1A and stator core materials of the shape shown in Figure 3 were manufactured. Specifically, the rotor core materials were manufactured by punching the non-directional electromagnetic steel sheets of each test number. Furthermore, intermediate materials for the stator core materials were manufactured by punching the non-directional electromagnetic steel sheets of each test number. The intermediate materials were then subjected to a relaxation annealing process at 800°C for 1 hour to manufacture the stator core materials.

[0207] The following evaluation tests were conducted on the rotor core materials and stator core materials for each test number. (Experiment 7) Magnetic property evaluation test (Experiment 8) Test on the thickness of the joint and the flat section. (Experiment 9) Hardness test of the inclined portion and the flat portion of the convergent part. The following will explain Experiments 7 through 9.

[0208] [(Experiment 7) Magnetic property evaluation test] Based on the method described above in [Method for Determining the Magnetic Properties of Rotor Core Material], the iron loss W5 / 1000 (W / kg) of the rotor core material for each test number was calculated. Furthermore, the dimensions of the test piece were set to 16mm × 8mm width × plate thickness. The obtained iron loss W5 / 1000 (W / kg) is listed in Table 4A. Based on the method described in [Method for Determining the Magnetic Properties of Stator Core Materials], the iron loss W10 / 400 (W / kg) of the stator core material for each test number was calculated. Furthermore, the dimensions of the test piece were set to 16mm × 8mm wide × plate thickness. The obtained iron loss W10 / 400 (W / kg) is listed in Table 4B.

[0209] [Table 4A]

[0210] [Table 4B]

[0211] [(Experiment 8) Test on the thickness of the inclined portion and the flat portion of the joint] Based on the method described above [Method for measuring the plate thickness PT14 of the flat portion 14 and the plate thickness PT121 of the inclined portion 121], the plate thickness PT14 of the flat portion 14 and the plate thickness PT121 of the inclined portion 121 of the rotor core material are determined. Furthermore, based on the method described above [Method for measuring the plate thickness PT24 of the flat portion 24 and the plate thickness PT221 of the inclined portion 221], the plate thickness PT24 of the flat portion 24 and the plate thickness PT221 of the inclined portion 221 of the stator core material are determined. The obtained plate thicknesses PT14 (mm), PT121 (mm), PT24 (mm), and PT221 (mm) are listed in Table 4 (Table 4A and Table 4B).

[0212] [(Experiment 9) Hardness test of the inclined portion and the flat portion of the convergent part] Based on the method described above [Method for determining Vickers hardness H14 of flat portion 14 and Vickers hardness H121 of inclined portion 121], the Vickers hardness H14 of flat portion 14 and the Vickers hardness H121 of inclined portion 121 of rotor core material are determined. Furthermore, based on the method described above [Method for determining Vickers hardness H24 of flat portion 24 and Vickers hardness H221 of inclined portion 221], the Vickers hardness H24 of flat portion 24 and the Vickers hardness H221 of inclined portion 221 of stator core material are determined. The obtained Vickers hardness H14 (HV), Vickers hardness H121 (HV), Vickers hardness H24 (HV), and Vickers hardness H221 (HV) are listed in Table 4.

[0213] [Evaluation Results] Referring to Table 4 (Table 4A and Table 4B), in the rotor core materials of the present invention, namely test numbers 1 to 29, the thickness of the inclined portion is 85% or less of the thickness of the flat portion, the Vickers hardness H14 of the flat portion is 180 HV or more, and the Vickers hardness H121 of the inclined portion is H14 + 40 HV or more. Furthermore, in the stator core materials of the present invention, namely test numbers 1 to 29, the thickness of the inclined portion is 85% or less of the thickness of the flat portion, the Vickers hardness H24 of the flat portion is 175 HV or more, and the Vickers hardness H221 of the inclined portion is the aforementioned Vickers hardness H24 ± 10 HV or less.

[0214] The above describes the embodiments of this disclosure. However, the above embodiments are merely examples for implementing this disclosure. Accordingly, this disclosure is not limited to the above embodiments, and the above embodiments may be appropriately modified for implementation without departing from its purpose.

[0215] 1: Rotor core 2: Stator core 10: Rotor core material 11: Through hole 12: Convergence 121: Inclined section 122: Bottom 13: Through hole 14: Flat area 15: Sudden pole 16: Through hole 20: Stator core material 21: Teeth 22: Convergence 221: Inclined section 222: Bottom 24: Flat area IIA-IIA: Line Segment IIB-IIB: Line Segment X: Direction Y: direction Z: Direction PT121: Plate thickness PT14: Plate thickness PT221: Plate Thickness PT24: Plate thickness

Claims

1. A non-directional electromagnetic steel sheet, the chemical composition of which, by mass%, contains: Si: 2.0~4.0%, Mn: 0.1~1.5%, P: less than 0.15%, S: less than 0.0030%, Al: 0.1~2.0%, C: less than 0.0050%, N: less than 0.0050%, O: less than 0.0500%, Cr: 0~0.50%, Ti: 0~0.0030%, Mo: 0~0.100%, Ni: 0~0.50%, Cu: 0~0.50%, Sn: 0~0.100%, Sb: 0~0.100%, Ca: 0~0.0050%, Mg: 0~0.0030%, Rare earth elements: 0~0.0100%, B: 0~0.0030%, Zn: 0~0.0030%, Ge: 0~0.0030%. As: 0~0.0100%, Co: 0~0.0500%, V: 0~0.0030%, Se: 0~0.0030%, Zr: 0~0.0030%, Nb: 0~0.0030%, Pb: 0~0.0030%, and Ga: 0~0.0030%, with the remainder consisting of Fe and impurities; its plate thickness t is less than 0.30 mm, and F1 as defined in formula (1) is 10.0 or more, F2 as defined in formula (2) is 8.5 or less, and F3 as defined in formula (3) is iron loss W5 / 1000 or less, and this iron loss W5 / 1000 is the iron loss at a frequency of 1000 Hz and a magnetic flux density of 0.5 T. F4 as defined in equation (4) is an iron loss W10 / 400 or more, and the iron loss W10 / 400 is the iron loss of the aforementioned non-directional electromagnetic steel plate at a frequency of 400Hz and a magnetic flux density of 1.0T after heat treatment at 800℃ for 1 hour; F1=4Si+3Al+2Mn (1) F2=2Si+3Al+Mn (2) F3=45-12Si-5Al-2Mn+1000×t / (5+6Si+5Al+3Mn) (3) F4=4+800×t / (5+6Si+5Al+3Mn) (4) Here, the symbols of each element in equations (1) to (4) are the content of the corresponding element in terms of mass % and t is the thickness of the aforementioned plate in mm.

2. As in request item 1, the non-directional electromagnetic steel plate, wherein, The aforementioned chemical composition contains one or more elements selected from the following groups: Cr: 0.01~0.50%, Ti: 0.0001~0.0030%, Mo: 0.001~0.100%, Ni: 0.01~0.50%, Cu: 0.01~0.50%, Sn: 0.001~0.100%, Sb: 0.001~0.100%, Ca: 0.0001~0.0050%, Mg: 0.0001~0.0030%, Rare Earth elements: 0.0001~0.0100%, B: 0.0001~0.0030%, Zn: 0.0001~0.0030%, Ge: 0.0001~0.0030%, As: 0.0001~0.0100%. Co: 0.0001~0.0500%, V: 0.0001~0.0030%, Se: 0.0001~0.0030%, Zr: 0.0001~0.0030%, Nb: 0.0001~0.0030%, Pb: 0.0001~0.0030%, and Ga: 0.0001~0.0030%.

3. For the non-directional electromagnetic steel sheet of Request 1, the yield stress is above 450MPa and the tensile strength at break is above 20%.

4. As in request item 1, the non-directional electromagnetic steel sheet, wherein, When the rolling direction is taken as the reference 0°, the magnetic flux density B50 of each angle direction with a 22.5° interval is defined as: B50(0°), B50(22.5°), B50(45°), B50(67.5°) and B50(90°). At this time, the average magnetic flux density B50ave defined by equation (5) is 1.65T or more; B50ave=(B50(0°)+2×B50(22.5°)+2×B50(45°)+2×B50(67.5°)+B50(90°)) / 8 (5).

5. As in request item 1, the non-directional electromagnetic steel sheet, wherein, After the aforementioned non-directional electromagnetic steel plate is heat-treated at 800°C for 1 hour, the iron loss W10 / 400 is below F4. Taking the rolling direction as the reference 0°, the magnetic flux density B1 in each angular direction with a 22.5° interval is defined as: B1(0°), B1(22.5°), B1(45°), B1(67.5°) and B1(90°). At this time, the average magnetic flux density B1ave defined by formula (6) is above 0.70T. When the direction of the maximum value of magnetic flux density B500 is taken as the reference 0°, the aforementioned magnetic flux density B500 in each angular direction at a 22.5° interval is defined as: B500(0°), B500(22.5°), B500(45°), B500(67.5°) and B500(90°). At this time, the average magnetic flux density B500ave defined by equation (7) is 1.98T or more; B1ave=(B1(0°)+2×B1(22.5°)+2×B1(45°)+2×B1(67.5°)+B1(90°)) / 8 (6) B500ave=(B500(0°)+2×B500(22.5°)+2×B500(45°)+2×B500(67.5°)+B500(90°)) / 8 (7).

6. The non-directional electromagnetic steel sheet of claim 1 has a thermal conductivity of 20 W / mK or higher at 20°C and a thermal conductivity of 23 W / mK or higher at 150°C.

7. A rotor core comprising: a plurality of stacked rotor core materials; wherein the rotor core materials are plate-shaped, and the chemical composition of the rotor core materials, in mass percent, contains: Si: 2.0~4.0%, Mn: 0.1~1.5%, P: less than 0.15%, S: less than 0.0030%, Al: 0.1~2.0%, C: less than 0.0050%, N: less than 0.0050%, O: less than 0.0500%, Cr: 0~0.50%, Ti: 0~0.0030%, Mo: 0~0.100%, Ni: 0~0.50%, Cu: 0~0.50%, Sn: 0~0.100%, Sb: 0~0.100%, Ca: 0~0.0050%, Mg: 0~0.0030%, rare earth elements: 0~0.0100%. B: 0~0.0030%, Zn: 0~0.0030%, Ge: 0~0.0030%, As: 0~0.0100%, Co: 0~0.0500%, V: 0~0.0030%, Se: 0~0.0030%, Zr: 0~0.0030%, Nb: 0~0.0030%, Pb: 0~0.0030%, and Ga: 0~0.0030%, with the remainder consisting of Fe and impurities; its plate thickness t is less than 0.30 mm, F1 as defined in formula (1) is 10.0 or more, F2 as defined in formula (2) is 8.5 or less, and F3 as defined in formula (3) is iron loss W5 / 1000 or less, and this iron loss W5 / 1000 is the iron loss at a frequency of 1000 Hz and a magnetic flux density of 0.5 T. F4 as defined in equation (4) is an iron loss W10 / 400 or more, and the iron loss W10 / 400 is the iron loss of the aforementioned rotor core material after heat treatment at 800℃ for 1 hour at a frequency of 400Hz and a magnetic flux density of 1.0T; F1=4Si+3Al+2Mn (1) F2=2Si+3Al+Mn (2) F3=45-12Si-5Al-2Mn+1000×t / (5+6Si+5Al+3Mn) (3) F4=4+800×t / (5+6Si+5Al+3Mn) (4) Here, the symbols of each element in equations (1) to (4) are the content of the corresponding element in terms of mass % and t is the thickness of the aforementioned plate in mm.

8. The rotor core as requested in item 7, wherein, The aforementioned rotor core material further includes: a convergent portion and a flat portion having a flat area; the aforementioned convergent portion includes: an inclined portion formed relative to the aforementioned flat portion; the thickness of the aforementioned inclined portion is less than 85% of the thickness of the aforementioned flat portion.

9. The rotor core as requested in item 8, wherein, In the cross-section covering the central axis of the aforementioned rotor core material, the Vickers hardness H14 at the center of the plate thickness in the aforementioned flat portion is 180HV or higher, and the Vickers hardness H121 at the center of the plate thickness in the aforementioned inclined portion is H14+40HV or higher.

10. A stator core comprising: a plurality of stator core materials stacked together; the stator core materials being in the shape of annular plates; the stator core materials including: a plurality of teeth arranged with gaps in the circumferential direction of the stator core materials and extending in the radial direction of the stator core materials; the chemical composition of the stator core materials, in mass percent, comprising: Si: 2.0~4.0%, Mn: 0.1~1.5%, P: less than 0.15%, S: less than 0.0030%, Al: 0.1~2.0%, C: less than 0.0050%, N: less than 0.0050%, O: less than 0.0500%, Cr: 0~0.50%, Ti: 0~0.0030%, Mo: 0~0.100%, Ni: 0~0.50%, Cu: 0~0.50%, Sn: 0~0.100%. Sb: 0~0.100%, Ca: 0~0.0050%, Mg: 0~0.0030%, Rare Earth Elements: 0~0.0100%, B: 0~0.0030%, Zn: 0~0.0030%, Ge: 0~0.0030%, As: 0~0.0100%, Co: 0~0.0500%, V: 0~0.0030%, Se: 0~0.0030%, Zr: 0~0.0030%, Nb: 0~0.0030%, Pb: 0~0.0030%, and Ga: 0~0.0030%, with the remainder consisting of Fe and impurities; its plate thickness t is less than 0.30 mm, F1 as defined in formula (1) is 10.0 or more, and F2 as defined in formula (2) is 8.5 or less. F4 as defined in Equation (4) is an iron loss W10 / 400 or higher and the iron loss W10 / 400 is an iron loss at a frequency of 400Hz and a magnetic flux density of 1.0T; In the cross section covering the central axis of the aforementioned stator core material, the Vickers hardness H24 at the center of the plate thickness of the aforementioned flat portion is 175HV or higher, and the Vickers hardness H221 at the center of the plate thickness of the aforementioned inclined portion is less than or equal to the aforementioned Vickers hardness H24 ± 10HV; F1=4Si+3Al+2Mn (1) F2=2Si+3Al+Mn (2) F4=4+800×t / (5+6Si+5Al+3Mn) (4) Here, the element symbols in Equations (1), (2) and (4) are the content of the corresponding element in terms of mass % and t is the aforementioned plate thickness in terms of mm.

11. The stator core of request item 10, wherein, The aforementioned stator core material further includes: a convergent portion and a flat portion having a flat area; the aforementioned convergent portion includes: an inclined portion formed relative to the aforementioned flat portion; the thickness of the aforementioned inclined portion is less than 85% of the thickness of the aforementioned flat portion.

12. A motor comprising: a rotor core as claimed in any one of claims 7 to 9, and a stator core as claimed in claim 10 or claim 11.

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