BR112020014943B1 - NON-ORIENTED ELECTRICAL STEEL SHEET - Google Patents

Abstract

The present invention relates to an unoriented electrical steel sheet including, as a chemical composition, in % by mass: C: 0.0030% or less; Si: 2.00% to 4.00%; Al: 0.01% to 3.00%; Mn: 0.10% to 2.00%; P: 0.005% to 0.200%; S: 0.0030% or less; Cu: more than 1.0% and 3.0% or less; Ni: 0.10% to 3.0%; one or more coarse precipitate-forming elements: more than 0.0005% and 0.0100% or less in total; a parameter Q (Q = [Si] +2 [Al] - [Mn]) where the Si content (% by mass) is defined as [Si], the Al content (% by mass) is defined as [Al ] and the Mn content (% by mass) is defined as [Mn]: 2.00 or more; Sn: 0.00% to 0.40%; Cr: 0.0% to 10.0% and the rest: Fe and impurities, in which the number of particles of a single Cu that have a diameter of less than 100 nm is 5 or more per 10 μm2, the orientation intensity of crystal {100} is 2.4 or more, the thickness is from 0.10 mm to 0.60 mm, and the average grain size is from 70 μm to 200 μm.

Description

Technical Field of the Invention

[0001] The present invention relates to an unoriented electrical steel sheet.

[0002] Priority is claimed by Japanese Patent Application No. 2018-058264 filed on March 26, 2018, the contents of which are incorporated herein by reference.

Related Technique

[0003] Unoriented electrical steel sheets are used, for example, for motor cores. Unoriented electrical steel sheets must have excellent magnetic characteristics in all directions parallel to the surface of the sheet (hereinafter, sometimes referred to as "all directions on the surface of the sheet"), such as low iron loss and high density. of magnetic flux. In particular, an unoriented electrical steel sheet used for a Hybrid Electric Vehicle (HEV) engine is required to perform well at an ultra-high rotational speed of about 10,000 rpm.

[0004] At this rotational speed, while a material is required that has a strength to withstand centrifugal force, excellent iron loss at high frequency and high magnetic flux density, it is also required elongation of the material to prevent the formation of chips during machining.

State of the Art Document Patent Document

[0005] Patent Document 1 Japanese Unexamined Patent Application, First Publication No. H3-126845

[0006] Patent Document 2 Japanese Unexamined Patent Application, First Publication No. 2006-124809

[0007] Patent Document 3 Japanese Unexamined Patent Application, First Publication No. S61-231120

[0008] Patent Document 4 Japanese Unexamined Patent Application, First Publication No. 2004-197217

[0009] Patent Document 5 Japanese Unexamined Patent Application, First Publication No. H5-140648

[0010] Patent Document 6 Japanese Unexamined Patent Application, First Publication No. 2008-132534

[0011] Patent Document 7 Japanese Unexamined Patent Application, First Publication No. 2004-323972

[0012] Patent Document 8 Japanese Unexamined Patent Application, First Publication No. S62-240714

[0013] Patent Document 9 Japanese Unexamined Patent Application, First Publication No. 2011-157603

[0014] Patent Document 10 Japanese Unexamined Patent Application, First Publication No. 2008-127659

Description of the Invention Problems to be Solved by the Invention

[0015] An object of the present invention is to provide an unoriented electrical steel sheet that has excellent magnetic characteristics and excellent strength and elongation.

Ways to Solve the Problem

[0016] The present inventors have intensively studied to solve the above problems. As a result, it became clear that it is important to make appropriate chemical composition, thickness and average grain size. It has also become clear that, in the manufacture of such unoriented electrical steel sheet, when a steel strip to be cold-rolled, such as a hot-rolled steel strip, has to be obtained, it is important to control the proportion of crystals columns and average grain size in casting or rapid solidification of molten steel to control the roll reduction of cold rolling and to control sheet pass stress and cooling rate during final annealing.

[0017] The present inventors conducted further intensive studies based on such findings and, as a result, arrived at the various aspects of the invention described below.

[0018] (1) An unoriented electrical steel sheet according to an aspect of the present invention includes, as a chemical composition, in wt%: C: 0.0030% or less; Si: 2.00% to 4.00%; Al: 0.01% to 3.00%; Mn: 0.10% to 2.00%; P: 0.005% to 0.200%; S: 0.0030% or less; Cu: more than 1.0% and 3.0% or less; Ni: 0.10% to 3.0%; one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd: more than 0.0005% and 0.0100% or less in total; a Q parameter represented by Formula 1 where the Si content (% by mass) is defined as [Si], the Al content (% by mass) is defined as [Al] and the Mn content (% by mass) is set to [Mn]: 2.00 or more; Sn: 0.00% to 0.40%; Cr: 0.0% to 10.0% and the remainder: Fe and impurities, where the number of particles of an elemental Cu that has a diameter of less than 100 nm is 5 or more per 10 μm2, the orientation intensity crystal grain size {100} is 2.4 or more, the thickness is 0.10 mm to 0.60 mm, and the average grain size is 70 μm to 200 μm. Q = [Si] +2 [Al] - [Mn] (Formula 1)

[0019] (2) The unoriented electrical steel sheet according to (1), wherein, in the chemical composition, Sn: 0.02% to 0.40% can be satisfied.

[0020] (3) The non-oriented electrical steel sheet according to (1) or (2), where, in the chemical composition, Cr: 0.2% to 10.0% can be satisfied.

Effects of the Invention

[0021] According to the present invention, once the chemical composition, thickness and average grain size are appropriate, it is possible to provide an unoriented electrical steel sheet that has excellent magnetic characteristics and excellent strength and elongation.

Brief Description of the Drawings

[0022] Figure 1 is a diagram showing the relationship between the Ni content and the EL in a case where the Cu content is 1.5%.

[0023] Figure 2 is a diagram showing the relationship between the Ni content and the EL in a case where the Cu content is 0.1%.

Modalities of the Invention

[0024] Hereinafter, embodiments of the present invention will be described in detail. It is obvious that the present invention is not to be construed as being limited to the following embodiments.

[0025] First, the chemical compositions of an unoriented electrical steel sheet according to an embodiment of the present invention and the cast steel used to manufacture the same will be described. Although details are described later, the unoriented electrical steel sheet according to the embodiment of the present invention is manufactured by casting and hot rolling the molten steel or fast solidifying the molten steel, cold rolling, final annealing and so on. against. Therefore, for the chemical compositions of unoriented electrical steel sheet and cast steel, not only the characteristics of unoriented electrical steel sheet but also these treatments are considered.

[0026] In the following description, "%", which is a unit of the amount of each element contained in the unoriented electrical steel sheet or cast steel, means "% by mass", unless otherwise specified .

[0027] In addition, the numerical limit range described below includes a minimum limit and a maximum limit. Numerical values that indicate "more than" or "less than" do not fall within the numerical range. "%", in relation to the amount of each element, means "% by mass".

[0028] The non-oriented electrical steel sheet according to the present embodiment includes, as a chemical composition: C: 0.0030% or less; Si: 2.00% to 4.00%; Al: 0.01% to 3.00%; Mn: 0.10%. 2.00%; P: 0.005% to 0.200%; S: 0.0030% or less; Cu: more than 1.0% and 3.0% or less; Ni: 0.10% to 3.0%; one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd: more than 0.0005% and 0.0100% or less in total; a Q parameter represented by Formula 1 where the Si content (% by mass) is defined as [Si], the Al content (% by mass) is defined as [Al] and the Mn content (% by mass) is set to [Mn]: 2.00 or more; Sn: 0.00% to 0.40%; Cr: 0.0% to 10.0%, and the rest: Fe and impurities. Q = [Si] +2 [Al] - [Mn] (Formula 1)

[0029] Examples of impurities include those contained in raw materials, such as ore and scrap metal, and those contained in manufacturing steps. (C: 0.0030% or less)

[0030] C increases iron loss and causes magnetic aging. Therefore, the lower the C content, the better. Such a phenomenon is noticeable when the C content is more than 0.0030%. For this reason, the C content is defined as 0.0030% or less. The reduction in C content also contributes to a uniform improvement in magnetic characteristics in all directions on the sheet surface.

[0031] The upper limit of the C content is more preferably 0.0020. The lower limit of the C content is preferably as low as possible, but is not particularly limited and is preferably 0.0005 or more taking into account the costs of removing C from the steel. (Si: 2.00% to 4.00%)

[0032] Si reduces iron loss by increasing electrical resistance and eddy current loss, and improves core drilling workability by increasing the throughput rate.

[0033] When the Si content is less than 2.00%, these action effects cannot be obtained sufficiently. Therefore, the Si content is defined as 2.00% or more. On the other hand, when the Si content is more than 4.00%, the magnetic flux density decreases, the drilling workability decreases due to an excessive increase in hardness, and cold rolling becomes difficult. Therefore, the Si content is defined as 4.00% or less.

[0034] The lower limit of the Si content is preferably 2.30% and more preferably 2.50%. The upper limit of the Si content is preferably 3.70% and more preferably 3.50%. (Al: 0.01% to 3.00%)

[0035] Al reduces iron loss by increasing electrical resistance and reducing eddy current loss.

[0036] Al also contributes to an improvement in the relative magnitude of the B50 magnetic flux density in relation to the saturation magnetic flux density. In this document, the B50 magnetic flux density is the magnetic flux density in a magnetic field of 5000 A/m. When the Al content is less than 0.01%, these action effects cannot be obtained sufficiently. Therefore, the Al content is defined as 0.01% or more. On the other hand, when the Al content is more than 3.00%, the magnetic flux density decreases, the throughput rate decreases, and the drilling work capacity decreases. Therefore, the Al content is defined as 3.00% or less.

[0037] The lower limit of Al content is preferably 0.10% and more preferably 0.20%. The upper limit of Al content is preferably 2.50% and more preferably 2.00%. (Mn: 0.10% to 2.00%)

[0038] Mn reduces iron loss by increasing electrical resistance and reducing eddy current loss. When Mn is contained, in a texture obtained by means of primary recrystallization, a plane parallel to the plate surface tends to be a plane in which crystals of a {100} plane (hereinafter, sometimes called {100} crystal) are developed. Crystal {100} is a crystal suitable for uniform improvement in magnetic characteristics in all directions on the sheet surface.

[0039] Furthermore, the higher the Mn content, the higher the MnS precipitation temperature and the greater the MnS precipitation. For this reason, the higher the Mn content, the lower the probability of precipitation of fine MnS that has a particle size of about 100 nm, which inhibits recrystallization and grain growth in the final annealing.

[0040] When the Mn content is less than 0.10%, these action effects cannot be sufficiently obtained. Therefore, the Mn content is defined as 0.10% or more. On the other hand, when the Mn content is more than 2.00%, the grains do not grow sufficiently in the final annealing and the iron loss increases. Therefore, the Mn content is defined as 2.00% or less.

[0041] The lower limit of the Mn content is preferably 0.15% and more preferably 0.20%. The upper limit of the Mn content is preferably 1.50% and more preferably 1.00%. (P: 0.005% to 0.200%)

[0042] P has the effect of improving the strength of non-oriented electrical steel sheet. When the P content is less than 0.005%, the effect of increasing strength cannot be obtained. When the P content is more than 0.200%, the working capacity decreases, so the P content is set to 0.005% and 0.200%.

[0043] The lower limit of P content is preferably 0.008% and more preferably 0.010%. The upper limit of P content is preferably 0.180% and more preferably 0.150%. (S: 0.0030% or less)

[0044] S is not an essential element and is contained, for example, as an impurity in steel.

[0045] S inhibits recrystallization and grain growth in the final annealing due to the precipitation of fine MnS. Therefore, the lower the S content, the better. The increase in iron loss and decrease in magnetic flux density due to such inhibition of recrystallization and grain growth are noticeable when the S content is more than 0.0030%. Therefore, the S content is set to 0.0030% or less.

[0046] The upper limit of the S content is preferably 0.0025% and more preferably 0.0020%. Since the lower limit of S content is preferably as low as possible, there is no specific limitation. However, since the costs of removing S from steel are unnecessarily high, 0.0005 or more is desirable. (Cu: more than 1.0% and 3.0% or less)

[0047] Cu is an essential element for obtaining a non-oriented electrical steel sheet that has high strength.

[0048] When the Cu content is less than 1.0%, the strength becomes insufficient. On the other hand, when the Cu content is more than 3.0%, the hardness decreases significantly and fractures occur easily. Therefore, the Cu content is defined to be more than 1.0% and 3.0% or less.

[0049] The lower limit of the Cu content is preferably 1.2% and more preferably 1.5%. The upper limit of Cu content is preferably 2.5% and more preferably 2.0%. (Ni: 0.10% to 3.0%)

[0050] Ni is a necessary element to improve elongation.

[0051] Although details are described later, in particular, in a case where the crystal orientation intensity is 2.4 or more, Cu is contained in more than 1.0% and 3.0% or less and a or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd are contained in more than 0.0005% and 0.0100% or less, the effect of improving elongation is exhibited by addition of Ni in the range of 0.10% to 3.0%.

[0052] When Ni is contained in less than 0.10%, the effect cannot be obtained. On the other hand, when the Ni content is more than 3.0%, conversely, the elongation decreases. For this reason, the Ni content is set to 0.10% to 3.0%.

[0053] The lower limit of Ni content is preferably 0.15% and more preferably 0.20%. The upper limit of the Ni content is preferably 2.5% and most preferably 2.2%. (One or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd: more than 0.0005% and 0.0100% or less in total)

[0054] Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd react with S in molten steel during casting of molten steel or rapid solidification to form precipitates of sulfides, oxysulfides or both.

[0055] Hereinafter, Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd may be collectively referred to as a "coarse precipitate-forming element".

[0056] The particle size of precipitates containing the element forming coarse precipitates is about 1 μm to 2 μm, which is much larger than the particle size of fine precipitates such as MnS, TiN and AlN (about of 100 nm). For this reason, such fine precipitates formed at grain boundaries adhere to precipitates from the coarse precipitate-forming element and are less likely to inhibit recrystallization and grain growth during final annealing.

[0057] When the total amount of the coarse precipitate-forming element is 0.0005% or less, these effects cannot be sufficiently obtained. Therefore, the total amount of the coarse precipitate-forming element is set to more than 0.0005%. On the other hand, when the total amount of the coarse precipitate-forming element is more than 0.0100%, the total amount of sulfides or oxysulfides or both becomes excessive, and recrystallization and grain growth in the final annealing are inhibited. Therefore, the total amount of the coarse precipitate-forming element is set to 0.0100% or less.

[0058] The lower limit of the amount of the coarse precipitate-forming element is preferably 0.0010% and more preferably 0.0020%. The upper limit of the amount of the coarse precipitate-forming element is preferably 0.0090% and more preferably 0.0080%. (Q parameter: 2.00 or more)

[0059] To suppress the occurrence of ferrite-austenite transformation (α-Y transformation), the value of parameter Q is set to 2.00 or more.

[0060] When the Q parameter represented by Formula 1 is less than 2.00, ferrite-austenite transformation (α-Y transformation) may occur. Therefore, during casting of molten steel or rapid solidification, the columnar crystals formed are fractured by the α-Y transformation or the average grain size decreases. Furthermore, α-Y transformation can occur during final annealing. Therefore, when the Q parameter is less than 2.00, the desired magnetic characteristics cannot be obtained.

[0061] When the Q parameter is 2.00 or more, the α-Y transformation does not occur. Therefore, its maximum limit is not particularly defined, but naturally becomes 10 or less from the specified ranges of Si, Al and Mn.

[0062] The lower limit of the Q parameter is preferably 2.50.

[0063] Sn and Cr are not essential elements, but are optional elements that can be properly contained in the unoriented electrical steel sheet up to a predetermined amount. (Sn: 0.00% to 0.40%)

[0064] The Sn develops a crystal suitable for improving the magnetic characteristics through primary recrystallization. Therefore, when Sn is contained, the texture in which a {100} crystal suitable for a uniform improvement in the magnetic characteristics in all directions on the surface of the sheet is developed is easily obtained through primary recrystallization. Sn suppresses oxidation and nitriding of the steel sheet surface during final annealing and suppresses variation in grain size. Therefore, Sn can be contained.

[0065] To sufficiently obtain these action effects, the amount of Sn is preferably set to 0.02% or more. On the other hand, when the amount of Sn is more than 0.40%, the above-mentioned action effects are saturated and the costs increase unnecessarily or the grain growth in the final annealing is suppressed. Therefore, the Sn content is set to 0.40% or less.

[0066] The lower limit of the Sn content is more preferably 0.05%. The upper limit of the Sn content is preferably 0.30% and more preferably 0.20%. (Cr: 0.0% to 10.0%)

[0067] Cr reduces iron loss at high frequency. A reduction in iron loss at high frequency contributes to the high rotational speed of rotating machines and the high rotational speed contributes to a reduction in size and an increase in efficiency of rotating machines. Cr reduces iron loss, such as high frequency iron loss, by increasing electrical resistance and reducing eddy current loss. Cr reduces stress sensitivity and thus contributes to lessening the reduction in magnetic characteristics due to the compressive stress introduced when a core is formed and the reduction in magnetic characteristics due to the compressive stress acting during high-speed rotation. Therefore, Cr may be contained.

[0068] To get these action effects sufficiently, the amount of Cr is preferably set to 0.2% or more. On the other hand, when the Cr content is more than 10.0%, the magnetic flux density decreases and the costs increase. Therefore, the Cr content is set to 10.0% or less.

[0069] The lower limit of the Cr content is more preferably 0.4%. The upper limit of the Cr content is preferably 5.0% and more preferably 3.0%.

[0070] The impurities contained in the remainder indicate those that are incorporated from ore or scrap as a raw material or from the manufacturing environment when steel is manufactured industrially. These impurities are preferably restricted in order to sufficiently exhibit the effects of the present embodiment. Furthermore, since the amount of impurities is preferably small, it is not necessary to limit the lower limit, and the lower limit of the impurities can be 0%.

[0071] The aforementioned steel composition can be measured by means of a general steel analysis method. For example, the composition of steel can be measured using the method described in JIS G 12111258.

[0072] Next, the texture of the non-oriented electrical steel sheet will be described according to the embodiment of the present invention.

[0073] In the unoriented electrical steel sheet according to the present embodiment, the orientation intensity of crystal {100} is 2.4 or more. When the crystal orientation strength {100} is less than 2.4, there may be a decrease in magnetic flux density and an increase in iron loss or variations in magnetic characteristics between directions parallel to the sheet surface.

[0074] The higher the intensity, the better. Therefore, the upper limit is not particularly defined.

[0075] The intensity of crystal orientation {100} can be measured by means of an X-ray diffraction method or an Electron BackScatter Diffraction (EBSD) method. Since the reflection angles and so on of the sample's X-ray and electron beam are different for each crystal orientation, the crystal orientation intensity can be obtained from the reflection intensity and so on based on in a sample of random orientation.

[0076] Specifically, the {100} crystal orientation intensity can be obtained by the {100} crystal orientation reflection intensity (i(100)) of a target sample to the {100} crystal orientation reflection intensity (I(100)) of a randomly oriented sample, that is, i(100)/I(100).

[0077] Next, elementary Cu particles will be described in the non-oriented electrical steel sheet according to the embodiment of the present invention. In the unoriented electrical steel sheet according to the present embodiment, the number of elementary Cu particles having a diameter (particle size) of less than 100 nm is 5 or more per 10 µm 2 .

[0078] In the present document, among the elementary Cu particles, particles that have a particle size of less than 100 nm can increase the mechanical strength and have an action of not deteriorating the magnetic characteristics. On the other hand, among elementary Cu particles, particles having particle size equal to or greater than 100 nm have the effect of increasing the mechanical strength but deteriorating the magnetic characteristics.

[0079] When the number of elementary Cu particles having a diameter of less than 100 nm as described above is less than 5 per 10 μm2, the mechanical strength is insufficiently improved or deterioration of the magnetic characteristics occurs. Therefore, the number of elementary Cu particles that have a diameter of less than 100 nm is set to 5 or more per 10 μm2. Since the greater the number of elemental Cu particles having a diameter of less than 100 nm the more the strength can be improved without adversely affecting the iron loss, the maximum limit thereof is not particularly specified.

[0080] It is more preferable that the number of elementary Cu particles having a diameter of less than 100 nm is 100 or more per 10 μm 2 .

[0081] Particles smaller than 100 nm can be observed, for example, with a Transmission Electron Microscope (TEM). With a Scanning Electron Microscope (SEM), it is difficult to observe particles smaller than 100 nm, depending on the model. For the point-of-observation sample fit in TEM, for example, an observation point reduction method or a replica method is used to transfer a precipitate onto an organic film. Since it is difficult to observe elemental Cu particles through the replication method, a sample fit reduction method is preferably used.

[0082] Specifically, the diameter of elemental Cu particles according to the present embodiment is obtained by observing a range of 10 μm2 or more by TEM, counting the number in the observation range, and averaging with the measurement area. The TEM observation range is more preferably 20 µm 2 or more and even more preferably 30 µm 2 or more. Particle composition is identified by a proxy in a TEM diffraction pattern.

[0083] Next, the average grain size of the non-oriented electrical steel sheet will be described according to the embodiment of the present invention.

[0084] The average grain size of the non-oriented electrical steel sheet according to the present embodiment is from 70 μm to 200 μm. When the average grain size is less than 70 μm, the W10/400 iron loss is high. In the present document, the W10/400 iron loss is an iron loss at a magnetic flux density of 1.0 T and a frequency of 400 Hz. On the other hand, when the average grain size is more than 200 μm, W10/400 iron loss is deteriorated and cracks are induced during machining.

[0085] In the present embodiment, the grain size means an equivalent circular diameter of the grain.

[0086] The average grain size means the grain size per grain. For example, EBSD measurement is performed, a 5 mm2 swath is observed and the average grain size in the observed visual field can be obtained by a program (eg OIM Analysis).

[0087] Next, the thickness of the non-oriented electrical steel sheet will be described according to the embodiment of the present invention.

[0088] The thickness of the unoriented electrical steel sheet according to the present embodiment is, for example, 0.10 mm or more and 0.60 mm or less. When the thickness of unoriented electrical steel sheet is more than 0.60mm, it is not possible to obtain excellent iron loss at high frequency. Therefore, the thickness of unoriented electrical steel sheet is set to 0.60 mm or less.

[0089] When the thickness of the unoriented electrical steel sheet is less than 0.10 mm, the magnetic characteristics on the surface of the unoriented electrical steel sheet that have low stability become more dominant than the magnetic characteristics inside that have high stability. When the thickness of unoriented electrical steel sheet is less than 0.10 mm, it becomes difficult to pass the sheets through a final annealing annealing line or the number of unoriented electrical steel sheets required for a core of a given size increases, which leads to a reduction in productivity and an increase in manufacturing costs due to an increase in the number of steps. Therefore, the thickness of unoriented electrical steel sheet is set to 0.10 mm or more.

[0090] The minimum limit of thickness of unoriented electrical steel sheet is more preferably 0.20 mm. The maximum thickness limit of unoriented electrical steel sheet is more preferably 0.50 mm.

[0091] Next, the magnetic characteristics and mechanical properties of the non-oriented electrical steel sheet will be described according to the embodiment of the present invention. Unoriented electrical steel sheet according to the present embodiment can exhibit magnetic characteristics represented by a B50 magnetic flux density in a ring magnetism measurement of 1.63 T or greater and a W10/400 iron loss of 11 x [0.45 + 0.55 x {0.5 x (t/0.20) + 0.5 x (t/0.20)2}] W/kg or less when the electrical steel sheet thickness is not oriented is t (mm).

[0092] In measuring ring magnetism, a ring-shaped sample collected from unoriented electrical steel sheet, for example, a ring-shaped sample that has an outside diameter of 5 inches (12.70 cm) and a 4 inch (10.16 cm) inside diameter is excited to cause a magnetic flux to flow around the entire circumference of the sample. The magnetic characteristics obtained by measuring the ring magnetism reflect the structure in all directions on the sheet surface.

[0093] In addition, the unoriented electrical steel sheet according to the present embodiment can obtain mechanical properties that have a strength (tensile strength TS) of 590 MPa or more and a total elongation (EL) of 10% or more .

[0094] In this document, the mechanical properties can be tested using the method described in the JIS Z 2241 standard. A test specimen to be used is a JIS specimen No. 5 described in the JIS Z 2201 standard, in which a parallel portion of the specimen is aligned with a rolling direction of a steel plate. Then, the tensile strength at the time of a tensile test can be described as TS and the total elongation can be described as EL.

[0095] Subsequently, the relationship between the chemical composition of the non-oriented electrical steel sheet according to the present embodiment and the magnetic characteristics and mechanical properties will be described. As described above, the unoriented electrical steel sheet according to the present embodiment needs to have the crystal orientation intensity {100} of 2.4 or more and reach a strength and elongation to obtain good magnetic characteristics. The greater the intensity of crystal orientation, the more desirable it is. Therefore, no specific maximum limit is specified.

[0096] To obtain a high-strength unoriented electrical steel sheet, the Cu content needs to be more than 1.0%. Furthermore, to reduce iron loss, it is necessary to include conditions under which the grains are likely to grow, ie, contain more than 0.0005% and 0.0100% or less of the coarse precipitate-forming element.

[0097] As shown in Figure 1, provided that the crystal orientation intensity {100} is 2.9, when a case where 0.004% of Mg, which is the aforementioned coarse precipitate-forming element, is contained (data from "♦" in the graph in Figure 1) is compared with a case where Mg is not contained (data from "◊" in the graph in Figure 1), it can be seen that the EL decreases in a case where Mg, which is the element forming coarse precipitates is contained when the Ni content is small.

[0098] On the other hand, as shown in Figure 2, in a case where the Cu content is small, such a tendency is not observed. That is, even in a case where the Ni content is changed, the presence or absence of Mg, which is the element forming coarse precipitates, and the crystal orientation intensity {100} do not affect the EL.

[0099] From the above results, it can be seen that, in a case where the Cu content is more than 1.0%, the relationship between the Cu content and Ni content changes when a precipitate-forming element coarse is contained.

[0100] As described above, in order to obtain strength and elongation and to obtain good magnetic characteristics, as can be seen from Figure 1, it is important to satisfy all conditions, including more than 0.0005% and 0.0100% or less of the coarse precipitate-forming element, more than 1.0% and 3.0% or less Cu, 0.10% to 3.0% Ni, and an {100} crystal orientation intensity of 2.4 or more.

[0101] The method of manufacturing the non-oriented electrical steel sheet according to the embodiment described above is not particularly limited, but the (1) method of hot coil annealing at high temperature + large reduction by cold rolling, ( 2) continuous thin slab casting method, (3) lubrication hot rolling method, and (4) strip casting method can be adopted.

[0102] In any of the methods, the chemical composition of the raw material, such as a board, is the chemical composition described in the item above. Afterwards, an embodiment of the method of manufacturing the non-oriented electrical steel sheet will be described.

(1) High temperature hot coil annealing method + cold rolling large reduction

[0103] First, a plate is manufactured in a steel fabrication step. After the slab is heated in a reheat furnace, rough rolling and finish rolling are performed continuously in a hot rolling step to obtain a hot rolled coil. Hot rolling conditions are not particularly limited.

[0104] A general manufacturing method, that is, a manufacturing method in which a plate heated to 1000°C to 1200°C is subjected to the finishing hot rolling completed at 700°C to 900°C and is then , rolled at 500°C to 700°C.

[0105] Then, hot coil annealing is performed on the hot rolled coil steel sheet. Through hot coil annealing, the grains are recrystallized and coarsely grown to a grain size of 300 to 500 μm.

[0106] Hot band annealing can be continuous annealing or batch annealing. From a cost point of view, hot strip annealing is preferably carried out by means of continuous annealing. To carry out continuous annealing, it is necessary to cultivate grains within a short period of time at a high temperature. By adjusting the amount of Si or the like so that the value of the Q parameter described above becomes 2.00 or more, a composition can be obtained with which ferrite-austenite transformation does not occur at a high temperature.

[0107] Then pickling is performed on the steel sheet before cold rolling.

[0108] Pickling is a necessary step to remove incrustations on the surface of the steel sheet. The pickling conditions are selected according to the scale removal situation. Encrustations can be removed with a grinder instead of pickling. In addition, washing with water can be carried out.

[0109] Then, cold rolling is performed on the steel sheet.

[0110] In the present document, in a high-quality electrical unoriented steel sheet that has a high Si content, when the grain size is too large, the steel sheet becomes embrittled and there is concern about brittle fractures in cold rolling. Therefore, the average grain size of steel sheet before cold rolling is generally limited to 200 μm or less. On the other hand, in the present manufacturing method, the average grain size before cold rolling is set to 300 to 500 μm and the subsequent cold rolling is carried out at a roll reduction of 90% to 97%. Roll reduction (%) can be calculated as "Roll reduction = (1 - (sheet thickness after cold rolling)/(sheet thickness before cold rolling)) x 100".

[0111] Instead of cold rolling, hot rolling can be performed at a temperature equal to or greater than the ductile-brittle transition temperature of the material from the point of view of avoiding brittle fractures.

[0112] Thereafter, when the final annealing is carried out, the recrystallized grains ND//<100> grow. Consequently, the intensity of the {100} plane increases and the probability of the presence of {100} oriented grains increases.

[0113] Then, the final annealing is performed on the steel sheet.

[0114] The final annealing conditions need to be determined to obtain a grain size with which the desired magnetic characteristics are obtained, but may be within the range of the final annealing conditions for common non-oriented electrical steel sheets.

[0115] The final annealing can be continuous annealing or batch annealing. From a cost point of view, the final annealing is preferably carried out by means of continuous annealing.

[0116] In the present manufacturing method, primary recrystallization and grain growth are caused by the final annealing, so that the average grain size can be from 70 μm to 200 μm. Through this final annealing, a texture in which a {100} crystal suitable for a uniform improvement in the magnetic characteristics in all directions on the sheet surface is obtained. In final annealing, for example, it is preferable that the hold temperature is set to 900°C or higher and 1000°C or lower and the hold time is set to 10 seconds or more and 60 seconds or less.

[0117] In the present manufacturing method, as a Cu precipitation treatment, annealing at 500°C to 700°C can be additionally performed. In this annealing, the amount of precipitation and the diameter of the precipitates can be changed by changing the annealing temperature and time.

[0118] Through the above steps, the non-oriented electrical steel sheet is obtained according to the embodiment of the present invention described above.

(2) Thin slab continuous casting method

[0119] In the thin slab continuous casting method, a slab having a thickness of 30 to 60 mm is manufactured in a steelmaking step, and the rough rolling in the hot rolling step is omitted. It is desirable that the columnar crystals are sufficiently developed with the thin plate and the {100} <011> orientation obtained by processing the columnar crystals by means of hot rolling is left on the hot rolled plate.

[0120] In this process, the columnar crystals grow so that the plane {100} is parallel to the surface of the steel sheet. For this purpose, it is desirable not to carry out electromagnetic stirring in the continuous casting. Furthermore, it is desirable to reduce fine inclusions in the molten steel that promote nucleation upon solidification as much as possible.

[0121] Then, the thin slab is heated in a reheat furnace, and then it is hot-rolled continuously in a hot-rolling step to obtain a hot-rolled coil.

[0122] Thereafter, the hot rolled coil steel sheet is subjected to hot coil annealing, pickling, cold rolling, final annealing and so on in the same manner as in "(1) Coil annealing method hot rolling at high temperature + large reduction by cold rolling". However, cold rolling can be performed with a rolling reduction of 80% to 97%.

[0123] Through the above steps, the non-oriented electrical steel sheet is obtained according to the embodiment of the present invention described above.

(3) Lubrication hot rolling method

[0124] First, a plate is manufactured in a steel fabrication step. After the slab is heated in a reheat furnace, rough rolling and finish rolling are performed continuously in a hot rolling step to obtain a hot rolled coil.

[0125] Normally, hot rolling is carried out without lubrication, however, in the method according to the present embodiment, hot rolling is carried out under appropriate lubrication conditions. When hot rolling is carried out under proper lubrication conditions, the shear strain introduced in the vicinity of the surface layer of the steel sheet is reduced. As a result, a machined structure having an RD//<011> orientation called the α fiber, which generally develops in the center of the steel sheet, can be developed in close proximity to the surface layer of the steel sheet.

[0126] For example, as described in the Japanese Unexamined Patent Application, First Publication No. H10-036912, the α fiber can be developed by mixing 0.5% to 20% of oil in the cooling water of the lamination roll at hot rolling as a lubricant during hot rolling and make the average coefficient of friction between a finishing hot rolling roll and steel plate 0.25 or less. The temperature conditions of hot rolling may not be particularly specified and may be the same as the temperature described in "(1) High Temperature Hot Coil Annealing Method + Large Reduction by Cold Rolling" above.

[0127] Then, the hot rolled coil steel sheet is subjected to hot coil annealing, pickling, cold rolling, final annealing and so on in the same manner as in "(2) Continuous slab casting method fine". According to the method described above, when the α-fiber is developed in the vicinity of the surface layer of the hot-rolled coil steel sheet, oriented grains {h11}<1/h 12>, particularly oriented grains {100}<012> to {411}<148>, are recrystallized in the subsequent hot coil annealing. When steel sheet is pickled and then subjected to cold rolling and final annealing, the oriented grains {100}<012> to {411}<148> are recrystallized. Consequently, the intensity of the {100} plane increases and the probability of the presence of {100} oriented grains increases.

[0128] Through the above steps, the non-oriented electrical steel sheet is obtained according to the embodiment of the present invention described above.

(4) Strip casting method

[0129] First, in a steelmaking step, a hot-rolled coil that has a thickness of 1 to 3.5 mm is manufactured by means of strip casting.

[0130] In strip casting, it is possible to obtain a steel plate that has a thickness equivalent to a directly hot-rolled coil by quickly cooling the molten steel between a pair of water-cooled rollers. At this point, by sufficiently increasing the temperature difference between the outermost surface of the steel sheet in contact with the water-cooled rollers and the molten steel, the solidified grains on the surface grow in the direction perpendicular to the steel sheet to form columnar crystals.

[0131] Through strip casting as described above, the molten steel having the above chemical composition can be quickly solidified on the surface of the cooling body that moves and renews. Consequently, a steel strip having a proportion of columnar crystals of 80% or more in terms of area fraction and an average grain size of 0.1 mm or more can be obtained.

[0132] When the proportion of columnar crystals is 80% or more, it is possible to obtain a texture in which a {100} crystal is developed by the final annealing. In the present manufacturing method, to make the proportion of columnar crystals 80% or more, for example, a condition can be adopted in which the temperature of the molten steel injected onto the surface of the cooling body which moves and renews is increased by 25°C or more from the solidification temperature. In particular, in a case where the temperature of the molten steel injected onto the surface of the moving and renewing cooling body is raised by 40°C or more from the solidification temperature, the proportion of columnar crystals can be made nearly 100%. , which is more preferable.

[0133] In the case where the molten steel is solidified under the condition that the proportion of these columnar crystals is 80% or more, sulfides or oxysulfides of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn or Cd, or both, are easily formed and the formation of fine sulfides such as MnS is suppressed, which is more preferable.

[0134] In a steel that has a BCC structure, the columnar crystals grow so that the {100} plane is parallel to the surface of the steel sheet. As the proportion of columnar crystals increases, the intensity of the {100} plane increases and the probability of the presence of oriented {100} grains increases. To increase the intensity of the {100} plane, it is important that the {100} plane is not changed as much as possible by transformation, machining or recrystallization. Specifically, by including Si, which is a ferrite-promoting element, and limiting the amount of Mn, which is an austenite-promoting element, it is important to form a single ferrite phase immediately after solidification to room temperature without forming a austenite phase at an elevated temperature.

[0135] Even if the austenite-ferrite transformation occurs, the plane {100} is partially maintained. However, by adjusting the amount of Si or the like so as to make the value of the Q parameter become 2.00 or more, a composition can be obtained with which the ferrite-austenite transformation does not take place at an elevated temperature. .

[0136] The smaller the average grain size of the steel strip, the greater the number of grains and the greater the area of the grain boundaries. In the final annealing recrystallization, crystals grow from the interior of the grains and from the grain boundaries.

[0137] The crystals that grow from the interior of the grains are {100} crystals desirable due to their magnetic characteristics, while the crystals that grow from the grain boundaries are crystals that are not desirable due to their magnetic characteristics, such as {111] crystals }<112>. Therefore, the larger the average grain size of the steel strip, the more easily the {100} crystals desirable for magnetic characteristics develop in the final annealing. Particularly, in a case where the average grain size of the steel strip is 0.1 mm or more, excellent magnetic characteristics are easily obtained. Therefore, it is preferable that the average grain size of the steel strip is 0.1 mm or more.

[0138] Then, the hot-rolled coil steel sheet obtained by strip casting is hot-rolled, and then the hot-rolled sheet obtained is annealed (hot coil annealing). A subsequent step can be performed directly without performing hot rolling. A subsequent step can also be carried out directly without performing hot coil annealing.

[0139] In the present document, in a case where a deformation of 30% or more is introduced into the steel sheet by hot rolling, when hot coil annealing is carried out at a temperature of 550°C or greater, recrystallization occurs at from the portion introduced by deformation and the crystal orientation can change. Therefore, in a case where a strain of 30% or more is introduced by hot rolling, hot coil annealing is not performed or is performed at a temperature at which recrystallization does not occur.

[0140] Then the steel sheet is subjected to pickling and so on and then subjected to cold rolling.

[0141] Cold rolling is an essential step to obtain the desired thickness of the product in this manufacturing method. However, when cold rolling reduction is excessive, it is not possible to obtain a desirable crystal orientation in a product. Therefore, the cold rolling reduction is preferably set to 90% or less, more preferably 85% or less, and even more preferably 80% or less. It is not necessary to particularly give the minimum limit of cold rolling rolling reduction, however, the minimum limit of rolling reduction is determined from the sheet thickness of the steel sheet before cold rolling and the desired thickness of the product.

[0142] In addition, in the present manufacturing method, when the cold rolling reduction is set to less than 40%, it may be difficult to ensure the accuracy of the thickness and flatness of the unoriented electrical steel sheet. Therefore, the cold rolling reduction is preferably set to 40% or more.

[0143] Even in a case where the surface properties and flatness required for a rolled steel sheet are not obtained, cold rolling is required. Therefore, cold rolling can be performed with minimal reduction per rolling for this purpose. Cold rolling can be performed by either a reversing mill or a reciprocating mill.

[0144] Instead of cold rolling, hot rolling can be performed at a temperature equal to or greater than the ductile-brittle transition temperature of the material from the point of view of avoiding brittle fractures.

[0145] In addition, instead of the aforementioned strip casting, when casting and hot rolling the molten steel, a steel strip is obtained in which the proportion of columnar crystals in the hot rolled crystal structure is 80% or more in terms of area fraction and the average grain size of 0.1 mm or more can be obtained, and this can be subjected to the same process of cold rolling, final annealing and so on as in the strip casting described above .

[0146] To make the proportion of columnar crystals be 80% or more, for example, it is preferable that the temperature difference between one surface and the other surface of a casting during solidification is 40°C or greater . This temperature difference can be controlled by the mold cooling structure, material, mold cone, mold flow and so on.

[0147] In the present manufacturing method, pickling, final annealing and so on can be carried out in the same manner as in "(1) High temperature hot coil annealing method + large reduction by cold rolling".

[0148] Through the above steps, the non-oriented electrical steel sheet is obtained according to the embodiment of the present invention described above.

[0149] In the unoriented electrical steel sheet according to the embodiment described above, the columnar crystals have a texture {100}<0vw> desirable for a uniform improvement in the magnetic characteristics of the unoriented electrical steel sheet, particularly the magnetic characteristics in all directions on the sheet surface.

[0150] Texture {100}<0vw> means a texture in which crystals are developed that have a plane parallel to the surface of the sheet that is a plane {100} and a rolling direction that is an orientation <0vw> (v and w are real numbers (excluding a case where v and w are 0)).

[0151] When the proportion of columnar crystals is 80% or more, a texture in which a {100} crystal is developed through final annealing can be obtained, which is preferable. The proportion of columnar crystals can be specified through microscopic observation.

[0152] In the case where molten steel is cast under the condition that the proportion of such columnar crystals is 80% or more, sulfides or oxysulfides of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn or Cd, or both, are easily formed and the formation of fine sulfides such as MnS is suppressed, which is more preferable.

[0153] The proportion of columnar crystals can be measured, for example, using the following procedure.

[0154] First, the cross section of a steel strip is polished and the cross section is chemically etched with a corrosive solution based on picric acid to reveal a solidifying structure. In the present document, the cross section of the steel strip can be an L section parallel to the longitudinal direction of the steel strip or a C section perpendicular to the longitudinal direction of the steel strip, however, the L section is generally used.

[0155] In this cross section, in a case where dendrites develop in the direction of the sheet thickness and penetrate into the overall sheet thickness, it is determined that the proportion of columnar crystals is 100%. In the case where a black granular structure (equiaxial grain) different from the dendrites can be observed in this cross section, a value obtained by dividing a value obtained by subtracting the thickness of this granular structure from the total thickness of the steel sheet by the total thickness of the steel sheet is used as the proportion of columnar crystals of steel sheet.

[0156] In addition, the non-oriented electrical steel sheet according to the embodiment described above can be manufactured, for example, by means of a manufacturing method for a non-oriented electrical steel sheet that includes: a manufacturing step of a board; a stage of performing rough rolling on the board; a step of obtaining a hot-rolled coil by performing finishing rolling on the steel plate that underwent rough rolling; a step of performing hot coil annealing on the hot rolled coil; a step of performing cold or hot rolling on the steel sheet that has undergone hot coil annealing; and a step of performing final annealing on the steel sheet that has undergone cold rolling or hot rolling.

[0157] In the step of obtaining the hot rolled coil, the rough rolling can be omitted or the hot rolled coil can be obtained by means of strip casting. Hot rolling by lubrication using the above lubricant can be performed on the hot rolled coil. In addition, the manufacturing method may further include a step of removing scale from the hot-rolled and annealed steel sheet.

[0158] In each of the manufacturing methods described above, it is preferable that the coarse precipitate-forming element is placed at the bottom of the final ladle before casting in the steelmaking step and a cast steel that contains an element other than the forming element of coarse precipitates is poured into the ladle to dissolve the coarse precipitate-forming element in the molten steel. Consequently, it is possible to hinder the dispersion of the coarse precipitate-forming element from the molten steel and to promote the reaction between the coarse precipitate-forming element and S.

[0159] The final ladle before casting in the steelmaking stage is, for example, a ladle directly above the intermediate ladle of a continuous casting machine.

Examples

[0160] Next, the unoriented electrical steel sheet according to the embodiment of the present invention will be specifically described with reference to examples. The examples shown below are merely examples of the unoriented electrical steel sheet according to the embodiment of the present invention, and the unoriented electrical steel sheet according to the present invention is not limited to the following examples.

First Test

[0161] In a first test, an unoriented electrical steel sheet was produced using the following method.

[0162] A 250 mm thick plate that has the chemical composition shown in Table 1 was prepared. Then, the board was subjected to hot rolling to produce hot rolled sheets having a thickness of 6.5 mm and a thickness of 2.0 mm, respectively.

[0163] The plate reheat temperature was 1200°C, the finishing temperature was 850°C and the winding temperature was 650°C.

[0164] After annealing the hot-rolled sheets obtained at 1050°C for 30 minutes, the encrustation in the surface layer was removed by pickling. Thereafter, the above hot-rolled sheets were cold-rolled to thicknesses of 0.65 mm and 0.20 mm, respectively. The roll reduction in cold rolling was set to 90% on any of the hot rolled sheets. In the final annealing, the steel strip was heated at a temperature increase rate of 20°C/s and, after 1000°C was reached, immersed for 15 seconds and cooled in air.

[0165] In tables 1 to 20, "---" indicates that the amount of the corresponding element is below the detection limit and the rest is Fe and impurities.

[0166] In addition, as a Cu precipitation treatment, the steel sheet was heated to 600 °C, immersed for 1 minute, and then cooled in air. In sample No. 12, the Cu precipitation treatment was omitted. For each of the unoriented electrical steel sheets, the number of elemental Cu particles that have a diameter of less than 100 nm per 10 μm2, the crystal orientation intensity I {100}, and the average grain size r were measured. . The results are shown in Table 2.

[0167] For each of the samples, the magnetic characteristics and mechanical properties of each of the unoriented electrical steel sheets were measured. For this measurement, a ring specimen having an outside diameter of 5 inches (12.70 cm) and an inside diameter of 4 inches (10.16 cm) was used. That is, a ring magnetism measurement was performed. The results are shown in Table 2.

[0168] A W10/400 iron loss equal to or less than an endpoint W0 (W/kg) represented by Formula 2 indicates an excellent value. That is, in the case where the thickness was 0.20 mm, an iron loss of 11.0 (W/kg) or less was rated as excellent, and in the case where the thickness was 0.65 mm, a loss iron of 46.7 (W/kg) or less was rated as excellent. A B50 magnetic flux density of 1.63 T or greater has been rated as excellent. W0 = 11 x [0.45 + 0.55 x {0.5 x (t/0.20) + 0.5 x (t/0.20)2}] (Formula 2)

[0169] Regarding the mechanical properties, since an unoriented electrical steel sheet used in an HEV motor needs to withstand an ultra-high rotational speed of almost 10,000 rpm, TS > 590 MPa and EL > 10% were considered as good criteria. Table 1 Table 2

[0170] As shown in Tables 1 and 2, in Samples Nos. 1 to 10, 14 to 16, 19 and 32 to 44, since the chemical composition was within the range of the present invention and the other conditions were within the ranges of present invention, good results were obtained in terms of magnetic characteristics and mechanical properties.

[0171] In Sample No. 11, since virtually no elements forming coarse precipitates were contained, the W10/400 iron loss was high.

[0172] In Sample No. 12, since the Cu content was very small, the tensile strength (TS) was insufficient.

[0173] In Sample No. 13, since the Cu content was very high, a fracture occurred during the test.

[0174] In Sample No. 17, since the plate thickness was very thick, the W10/400 iron loss was high.

[0175] In Sample No. 18, since Al was not contained in a specified amount and the Q parameter was less than 2.00, the tensile strength (TS) was low and the iron loss W10/400 was high.

[0176] In Sample No. 20, since the Si content was small, the W10/400 iron loss was high.

[0177] In Sample No. 21, since the Si content was large, a fracture occurred during the test.

[0178] In Sample No. 22, since the Mn content was small, the W10/400 iron loss was high.

[0179] In Sample No. 23, since the Mn content was large, the W10/400 iron loss was high and, as a result, the B50 magnetic flux density was lower.

[0180] In Sample No. 24, since the Al content was high, a fracture occurred during the test.

[0181] In Sample No. 25, since the P content was small, the tensile strength (TS) was low and, as a result, the B50 magnetic flux density was lower.

[0182] In Sample No. 26, since the P content was large, a fracture occurred during the test.

[0183] In Sample No. 27, since the S content was high, the W10/400 iron loss was high.

[0184] In Sample No. 28, since the Mg content was high, the W10/400 iron loss was high.

[0185] In Sample No. 29, since the Sn content was very high, a fracture occurred during the test.

[0186] In Sample No. 30, since the Cr content was very large, the total elongation EL was low, the iron loss W10/400 was high, and, as a result, the magnetic flux density B50 was lower .

[0187] In Sample No. 31, since the average grain size was large, the tensile strength (TS) and the total elongation EL were low and the W10/400 iron loss was high.

Second Test

[0188] In a second test, cast steel that has the chemical composition shown in Table 3 was cast to produce a plate and, in subsequent steps, an unoriented electrical steel plate was produced in the same way as in the first test. However, the thickness of the hot-rolled plate was limited to 2.0 mm and the thickness of the cold-rolled plate was limited to 0.20 mm. By changing manufacturing conditions in various ways, unoriented electrical steel sheets have been produced that have different strengths of crystal orientation. For each of the unoriented electrical steel sheets, the number of elemental Cu particles that have a diameter of less than 100 nm per 10 μm2, the crystal orientation intensity I {100}, and the average grain size r were measured. . The results are shown in Table 4.

[0189] In addition, the W10/400 iron loss, the B50 magnetic flux density, the tensile strength (TS) and the total elongation (EL) were also measured using the same procedure as in the first test. The results are shown in Table 4. Table 3 Table 4

[0190] As shown in Tables 3 and 4, in Samples 203 to 208 and 265 to 270, since the chemical composition was within the range of the present invention and the other conditions were within the range of the present invention, good results were obtained regarding magnetic characteristics and mechanical properties.

[0191] In samples Nos. 201 and 202, since the Ni content was very small, the total elongation (EL) was insufficient.

[0192] In Sample No. 209, since the Ni content was too large, the total elongation (EL) was insufficient.

[0193] In Samples Nos. 210 to 218, since the crystal orientation intensity I {100} was too low, the magnetic flux density B50 was insufficient.

[0194] In samples Nos. 219 to 227, since substantially no coarse precipitate-forming elements were contained, the W10/400 iron loss was deteriorated.

[0195] In Sample No. 228 to 236, since the Cu content was very small, the tensile strength (TS) was insufficient.

[0196] In Samples Nos 237 to 245, since the Cu content was very small and the crystal orientation intensity I {100} was very low, the tensile strength (TS) and magnetic flux density B50 were insufficient.

[0197] In Samples Nos. 246 to 254, since substantially no elements forming coarse precipitates were contained and the Cu content was very small, the W10/400 iron loss was deteriorated and the tensile strength (TS) was insufficient .

[0198] In Sample No. 255, since the Si content was small, the W10/400 iron loss was high.

[0199] In Sample No. 256, since the Si content was high, a fracture occurred during the test.

[0200] In Sample No. 257, since the Mn content was small, the W10/400 iron loss was high.

[0201] In Sample No. 258, since the Mn content was large, the W10/400 iron loss was high and, as a result, the B50 magnetic flux density was lower.

[0202] In Sample No. 259, since the Al content was high, a fracture occurred during the test.

[0203] In Sample No. 260, since the P content was small, the tensile strength (TS) was low and, as a result, the B50 magnetic flux density was lower.

[0204] In Sample No. 261, since the P content was high, a fracture occurred during the test.

[0205] In Sample No. 262, since the S content was high, the W10/400 iron loss was high.

[0206] In Sample No. 263, since the Mg content was high, the W10/400 iron loss was high.

[0207] In Sample No. 264, since the average grain size was large, the tensile strength (TS) and the total elongation EL were low and the W10/400 iron loss was high.

Third Test

[0208] A 30 mm thick plate was prepared, which has the chemical composition shown in Table 5.

[0209] Then the board was subjected to hot rolling to produce hot rolled sheets that have a thickness of 6.5 mm and a thickness of 2.0 mm. The plate reheat temperature was 1200°C, the finishing temperature was 850°C and the winding temperature was 650°C. Thereafter, the fouling on the surface layer was removed by pickling. Then, the hot-rolled sheets were cold-rolled to a thickness of 0.20 mm or 0.65 mm. In the final annealing, the steel strip was heated at a temperature increase rate of 20°C/s, and after 1000°C was reached, immersed for 15 seconds and cooled in air. Furthermore, as a Cu precipitation treatment, the steel sheet was heated to 600°C, immersed for 1 minute and then cooled in air.

[0210] In Sample No. 312, the Cu precipitation treatment was omitted. For each of the unoriented electrical steel sheets, the number of elemental Cu particles that have a diameter of less than 100 nm per 10 μm2, the crystal orientation intensity I {100}, and the average grain size r were measured. . The results are shown in Table 6. In addition, W10/400 iron loss, magnetic flux density, tensile strength (TS) and total elongation (EL) were also measured using the same procedure as in the first rehearsal. The results are shown in Table 6. Table 5 Table 6

[0211] As shown in Tables 5 and 6, in Samples Nos. 301 to 310, 314 to 316, 319 and 332 to 344, since the chemical composition was within the range of the present invention and the other conditions were within the ranges of present invention, good results were obtained in terms of magnetic characteristics and mechanical properties.

[0212] In Sample No. 311, since practically no element forming coarse precipitates was contained, the loss of iron W10/400 was high.

[0213] In Sample No. 312, since the Cu content was very small, the tensile strength (TS) was insufficient.

[0214] In Sample No. 313, since the Cu content was very high, a fracture occurred during the test.

[0215] In Sample No. 317, since the plate thickness was very thick, the W10/400 iron loss was high.

[0216] In Sample No. 318, since Al was not contained in a specified amount and the Q parameter was less than 2.00, the tensile strength (TS) was low and the iron loss W10/400 was high.

[0217] In Sample No. 320, since the Si content was small, the W10/400 iron loss was high.

[0218] In Sample No. 321, since the Si content was large, a fracture occurred during the test.

[0219] In Sample No. 322, since the Mn content was small, the W10/400 iron loss was high.

[0220] In Sample No. 323, since the Mn content was large, the W10/400 iron loss was high and, as a result, the B50 magnetic flux density was lower.

[0221] In Sample No. 324, since the Al content was high, a fracture occurred during the test.

[0222] In Sample No. 325, since the P content was small, the tensile strength (TS) was low and, as a result, the B50 magnetic flux density was lower.

[0223] In Sample No. 326, since the P content was large, a fracture occurred during the test.

[0224] In Sample No. 327, since the S content was high, the W10/400 iron loss was high.

[0225] In Sample No. 328, since the Mg content was high, the W10/400 iron loss was high.

[0226] In Sample No. 329, since the Sn content was very high, a fracture occurred during the test.

[0227] In Sample No. 330, since the Cr content was very large, the total elongation EL was low, the iron loss W10/400 was high and, as a result, the magnetic flux density B50 was lower .

[0228] In Sample No. 331, since the average grain size was large, the tensile strength (TS) and the total elongation EL were low and the W10/400 iron loss was high.

Fourth Test

[0229] In a fourth test, a 30 mm thick plate was prepared that has the chemical composition shown in Table 7.

[0230] Then, the plate was subjected to hot rolling to produce a hot rolled plate that has a thickness of 2.0 mm. The plate reheat temperature was 1200°C, the finishing temperature was 850°C and the winding temperature was 650°C. Thereafter, the fouling on the surface layer was removed by pickling. Thereafter, the hot-rolled sheet was cold-rolled to 0.20 mm.

[0231] By changing the manufacturing conditions in various ways, unoriented electrical steel sheets were produced that have different intensities of crystal orientation. For each of the unoriented electrical steel sheets, the number of elemental Cu particles that have a diameter of less than 100 nm per 10 μm2, the crystal orientation intensity I {100}, and the average grain size r were measured. . The results are shown in Table 8.

[0232] In addition, W10/400 iron loss, magnetic flux density, tensile strength (TS) and total elongation (EL) were also measured using the same procedure as in the first test. The results are shown in Table 8. Table 7 Table 8

[0233] As shown in Tables 7 and 8, in Samples Nos. 403 to 408 and 465 to 470, since the chemical composition was within the limits of the present invention and the other conditions were within the limits of the present invention, good results regarding magnetic characteristics and mechanical properties.

[0234] In Samples Nos. 401 and 402, since the Ni content was very small, the total elongation (EL) was insufficient.

[0235] In Sample No. 409, since the Ni content was too large, the total elongation (EL) was insufficient.

[0236] In Samples Nos. 410 to 418, since the crystal orientation intensity I {100} was too low, the magnetic flux density B50 was insufficient.

[0237] In Samples Nos. 419 to 427, since practically no element forming coarse precipitates was contained, the W10/400 iron loss was deteriorated.

[0238] In Samples Nos 428 to 436, since the Cu content was very small and the crystal orientation intensity I {100} was very low, the tensile strength (TS) and magnetic flux density B50 were insufficient.

[0239] In Samples Nos. 437 to 445, since the Cu content was very small, the tensile strength (TS) was insufficient.

[0240] In Samples Nos. 446 to 454, since substantially no elements forming coarse precipitates were contained and the Cu content was very small, the W10/400 iron loss was deteriorated and the tensile strength (TS) and B50 magnetic flux density were insufficient.

[0241] In Sample No. 455, since the Si content was small, the W10/400 iron loss was high.

[0242] In Sample No. 456, since the Si content was large, a fracture occurred during the test.

[0243] In Sample No. 457, since the Mn content was small, the W10/400 iron loss was high.

[0244] In Sample No. 458, since the Mn content was large, the W10/400 iron loss was high, and as a result, the B50 magnetic flux density was lower.

[0245] In Sample No. 459, since the Al content was high, a fracture occurred during the test.

[0246] In Sample No. 460, since the P content was small, the tensile strength (TS) was low and, as a result, the B50 magnetic flux density was lower.

[0247] In Sample No. 461, since the P content was large, a fracture occurred during the test.

[0248] In Sample No. 462, since the S content was high, the W10/400 iron loss was high.

[0249] In Sample No. 463, since the Mg content was high, the W10/400 iron loss was high.

[0250] In Sample No. 464, since the average grain size was large, the tensile strength (TS) and the total elongation EL were low and the W10/400 iron loss was high.

Fifth Test

[0251] A 250 mm thick plate was prepared that has the chemical composition shown in Table 9. Then, the plate was subjected to hot rolling to produce hot rolled sheets that have a thickness of 6.5 mm and a thickness of 2.0 mm, respectively.

[0252] The plate reheat temperature was 1200°C, the finishing temperature was 850°C and the winding temperature was 650°C. During hot rolling, lubrication rolling was performed by adding 10% oil to the cooling water. After annealing the hot-rolled sheets at 950°C for 1 minute, the fouling in the surface layer was removed by pickling.

[0253] Thereafter, the hot-rolled sheets were cold-rolled to 0.65 mm and 0.20 mm, respectively. The cold rolling reduction was set to 90% for any of the hot rolled sheets. In the final annealing, the steel strip was heated at a temperature increase rate of 20°C/s, and after 1000°C was reached, immersed for 15 seconds and cooled in air. Furthermore, as a Cu precipitation treatment, the steel sheet was heated to 600°C, immersed for 1 minute and then cooled in air.

[0254] In Sample No. 512, the Cu precipitation treatment was omitted.

[0255] For each of the unoriented electrical steel sheets, the number of elementary Cu particles that have a diameter of less than 100 nm per 10 μm2, the intensity of crystal orientation I {100} and the average size were measured of grain r. The results are shown in Table 10. In addition, W10/400 iron loss, magnetic flux density, tensile strength (TS) and total elongation (EL) were also measured using the same procedure as in the first rehearsal. The results are shown in Table 10. Table 9 Table 10

[0256] As shown in Tables 9 and 10, in Samples Nos. 501 to 510, 514 to 516, 519 and 532 to 544, since the chemical composition was within the range of the present invention and the other conditions were within the ranges of present invention, good results were obtained in terms of magnetic characteristics and mechanical properties.

[0257] In Sample No. 511, since practically no element forming coarse precipitates was contained, the loss of iron W10/400 was high.

[0258] In Sample No. 512, since the Cu content was very small, the tensile strength (TS) was insufficient.

[0259] In Sample No. 513, since the Cu content was very high, a fracture occurred during the test.

[0260] In Sample No. 517, since the plate thickness was very thick, the W10/400 iron loss was high.

[0261] In Sample No. 518, since Al was not contained in a specified amount and the Q parameter was less than 2.00, the tensile strength (TS) was low and the iron loss W10/400 was high.

[0262] In Sample No. 520, since the Si content was small, the W10/400 iron loss was high.

[0263] In Sample No. 521, since the Si content was large, a fracture occurred during the test.

[0264] In Sample No. 522, since the Mn content was small, the W10/400 iron loss was high.

[0265] In Sample No. 523, since the Mn content was large, the W10/400 iron loss was high, and as a result, the B50 magnetic flux density was lower.

[0266] In Sample No. 524, since the Al content was high, a fracture occurred during the test.

[0267] In Sample No. 525, since the P content was small, the tensile strength (TS) was low and, as a result, the B50 magnetic flux density was lower.

[0268] In Sample No. 526, since the P content was large, a fracture occurred during the test.

[0269] In Sample No. 527, since the S content was high, the W10/400 iron loss was high.

[0270] In Sample No. 528, since the Mg content was high, the W10/400 iron loss was high.

[0271] In Sample No. 529, since the Sn content was very high, a fracture occurred during the test.

[0272] In Sample No. 530, since the Cr content was very large, the total elongation EL was low, the iron loss W10/400 was high, and, as a result, the magnetic flux density B50 was lower .

[0273] In Sample No. 531, since the average grain size was large, the tensile strength (TS) and the total elongation EL were low and the W10/400 iron loss was high.

Sixth Test

[0274] In a sixth test, a 250 mm thick plate having the chemical composition shown in Table 11 was prepared. Then, the board was subjected to hot rolling to produce a hot rolled sheet having a thickness of 2.0 mm. The plate reheat temperature was 1200°C, the finishing temperature was 850°C and the winding temperature was 650°C.

[0275] During hot rolling, rolling with lubrication was performed by adding 10% oil to the cooling water. After annealing the hot-rolled sheet at 950°C for 1 minute, the fouling in the surface layer was removed by pickling.

[0276] Thereafter, the hot-rolled sheet was cold-rolled to 0.20 mm. The cold rolling reduction at this point was set to 90% on any of the hot rolled sheets. In the final annealing, the steel strip was heated at a temperature increase rate of 20°C/s, and after 1000°C was reached, immersed for 15 seconds and cooled in air. Furthermore, as a Cu precipitation treatment, the steel sheet was heated to 600°C, immersed for 1 minute and then cooled in air.

[0277] At this point, by changing the manufacturing conditions in various ways, unoriented electrical steel sheets were produced that have different intensities of crystal orientation. For each of the unoriented electrical steel sheets, the number of elemental Cu particles that have a diameter of less than 100 nm per 10 μm2, the crystal orientation intensity I {100}, and the average grain size r were measured. . The results are shown in Table 12.

[0278] In addition, the W10/400 iron loss, magnetic flux density, tensile strength (TS) and total elongation (EL) were also measured using the same procedure as in the first test. The results are shown in Table 12. Table 11 Table 12

[0279] As shown in Tables 11 and 12, in Samples Nos. 603 to 608 and Nos. 665 to 670, since the chemical composition was within the limits of the present invention and the other conditions were within the limits of the present invention, were obtained good results regarding magnetic characteristics and mechanical properties.

[0280] In Samples Nos. 601 and 602, since the Ni content was very small, the total elongation (EL) was insufficient.

[0281] In Sample No. 609, since the Ni content was too large, the total elongation (EL) was insufficient.

[0282] In Samples Nos. 610 and 618, since the crystal orientation intensity I {100} was too low, the magnetic flux density B50 was insufficient.

[0283] In Samples Nos. 619 to 627, since practically no element forming coarse precipitates was contained, the W10/400 iron loss was deteriorated.

[0284] In Samples Nos. 628 to 636, since the Cu content was very small and the crystal orientation intensity I {100} was very low, the tensile strength (TS) and magnetic flux density B50 were insufficient.

[0285] In Samples Nos. 637 to 645, since the Cu content was very small, the tensile strength (TS) was insufficient.

[0286] In Samples Nos. 646 to 654, since practically no elements forming coarse precipitates were contained, the Cu content was very small and the crystal orientation intensity I {100} was very low, the iron loss W10 /400 was deteriorated and the tensile strength TS and magnetic flux density B50 were insufficient.

[0287] In Sample No. 655, since the Si content was small, the W10/400 iron loss was high.

[0288] In Sample No. 656, since the Si content was large, a fracture occurred during the test.

[0289] In Sample No. 657, since the Mn content was small, the W10/400 iron loss was high.

[0290] In Sample No. 658, since the Mn content was large, the W10/400 iron loss was high and, as a result, the B50 magnetic flux density was lower.

[0291] In Sample No. 659, since the Al content was high, a fracture occurred during the test.

[0292] In Sample No. 660, since the P content was small, the tensile strength (TS) was low and, as a result, the B50 magnetic flux density was lower.

[0293] In Sample No. 661, since the P content was large, a fracture occurred during the test.

[0294] In Sample No. 662, since the S content was high, the W10/400 iron loss was high.

[0295] In Sample No. 663, since the Mg content was high, the W10/400 iron loss was high.

[0296] In Sample No. 664, since the average grain size was large, the tensile strength (TS) and the total elongation EL were low and the W10/400 iron loss was high.

Seventh Test

[0297] Hot-rolled coils of 1.0 mm thick and 3.25 mm thick were prepared, which have the chemical compositions shown in Table 13 below. This hot rolled coil was produced by flowing molten steel between a pair of rollers and solidifying a steel strip that has a columnar crystal ratio of 80% or more in terms of area fraction and an average grain size of 0. 1 mm or more was obtained. Then, for hot-rolled coils, fouling in the surface layer was removed by means of pickling.

[0298] After that, the hot rolled coils were cold rolled to 0.20mm and 0.65mm. In the final annealing, the steel strip was heated at a temperature increase rate of 20°C/s, and after 1000°C was reached, immersed for 15 seconds and cooled in air. Furthermore, as a Cu precipitation treatment, the steel sheet was heated to 600°C, immersed for 1 minute and then cooled in air. In Sample No. 712, the Cu precipitation treatment was omitted.

[0299] For each of the unoriented electrical steel sheets, the number of elementary Cu particles that have a diameter of less than 100 nm per 10 μm2, the crystal orientation intensity I {100} and the average size were measured of grain r. The results are shown in Table 14. In addition, W10/400 iron loss, magnetic flux density, tensile strength (TS) and total elongation (EL) were also measured using the same procedure as in the first rehearsal. The results are shown in Table 14. Table 13 Table 14

[0300] As shown in Tables 13 and 14, in Samples Nos. 701 to 710, 714 to 716, 719 and 732 to 744, since the chemical composition was within the range of the present invention and the other conditions were within the ranges of present invention, good results were obtained in terms of magnetic characteristics and mechanical properties.

[0301] In Sample No. 711, since practically no element forming coarse precipitates was contained, the loss of W10/400 iron was high.

[0302] In Sample No. 712, since the Cu content was very small, the tensile strength (TS) was insufficient.

[0303] In Sample No. 713, since the Cu content was very high, a fracture occurred during the test.

[0304] In Sample No. 717, since the plate thickness was very thick, the W10/400 iron loss was high.

[0305] In Sample No. 718, since Al was not contained in a specified amount and the Q parameter was less than 2.00, the tensile strength (TS) was low and the iron loss W10/400 was high.

[0306] In Sample No. 720, since the Si content was small, the W10/400 iron loss was high.

[0307] In Sample No. 721, since the Si content was high, a fracture occurred during the test.

[0308] In Sample No. 722, since the Mn content was small, the W10/400 iron loss was high.

[0309] In Sample No. 723, since the Mn content was large, the W10/400 iron loss was high and, as a result, the B50 magnetic flux density was lower.

[0310] In Sample No. 724, since the Al content was high, a fracture occurred during the test.

[0311] In Sample No. 725, since the P content was small, the tensile strength (TS) was low and, as a result, the B50 magnetic flux density was lower.

[0312] In Sample No. 726, since the P content was high, a fracture occurred during the test.

[0313] In Sample No. 727, since the S content was high, the W10/400 iron loss was high.

[0314] In Sample No. 728, since the Mg content was high, the W10/400 iron loss was high.

[0315] In Sample No. 729, since the Sn content was very high, a fracture occurred during the test.

[0316] In Sample No. 730, since the Cr content was very large, the total elongation EL was low, the iron loss W10/400 was high and, as a result, the magnetic flux density B50 was lower .

[0317] In Sample No. 731, since the average grain size was large, the tensile strength (TS) and the total elongation EL were low and the W10/400 iron loss was high.

Eighth Test

[0318] In an eighth test, a 1.0 mm thick hot-rolled coil having the chemical composition shown in Table 15 was prepared. Regarding this hot-rolled coil, molten steel was allowed to flow between a pair of rollers and solidified, and a steel strip that has a proportion of columnar crystals of 80% or more in terms of area fraction and an average size of grain of 0.1 mm or more was obtained. Then, for the hot rolled coil, the fouling in the surface layer was removed by pickling.

[0319] After that, the hot rolled coil was cold rolled to 0.20mm. In the final annealing, the steel strip was heated at a temperature increase rate of 20°C/s, and after 1000°C was reached, immersed for 15 seconds and cooled in air. Furthermore, as a Cu precipitation treatment, the steel sheet was heated to 600°C, immersed for 1 minute and then cooled in air.

[0320] At this point, by changing the manufacturing conditions in various ways, unoriented electrical steel sheets were produced that have different intensities of crystal orientation. For each of the unoriented electrical steel sheets, the number of elemental Cu particles that have a diameter of less than 100 nm per 10 μm2, the crystal orientation intensity I {100}, and the average grain size r were measured. . The results are shown in Table 16.

[0321] In addition, W10/400 iron loss, magnetic flux density, tensile strength (TS) and total elongation (EL) were also measured using the same procedure as in the first test. The results are shown in Table 16. Table 15 Table 16

[0322] As shown in Tables 15 and 16, in Samples Nos. 803 to 808 and 865 to 870, since the chemical composition was within the limits of the present invention and the other conditions were within the limits of the present invention, good results regarding magnetic characteristics and mechanical properties.

[0323] In Samples Nos. 801 and 802, since the Ni content was very small, the total elongation (EL) was insufficient.

[0324] In Sample No. 809, since the Ni content was too large, the total elongation (EL) was insufficient.

[0325] In Samples Nos. 810 to 818, since the orientation intensity of crystal {100} I was too low, the magnetic flux density B50 was insufficient.

[0326] In Samples Nos. 819 to 827, since practically no element forming coarse precipitates was contained, the W10/400 iron loss was deteriorated.

[0327] In Samples Nos. 828 to 836, since the Cu content was very small, the tensile strength (TS) was insufficient.

[0328] In Samples Nos. 837 to 845, since the Cu content was very small and the crystal orientation intensity I {100} was very low, the tensile strength (TS) and magnetic flux density B50 were insufficient.

[0329] In Samples Nos. 846 to 854, since virtually no elements forming coarse precipitates were contained and the Cu content was very small, the W10/400 iron loss was deteriorated and the TS tensile strength was insufficient.

[0330] In Sample No. 855, since the Si content was small, the W10/400 iron loss was high.

[0331] In Sample No. 856, since the Si content was large, a fracture occurred during the test.

[0332] In Sample No. 857, since the Mn content was small, the W10/400 iron loss was high.

[0333] In Sample No. 858, since the Mn content was large, the W10/400 iron loss was high and, as a result, the B50 magnetic flux density was lower.

[0334] In Sample No. 859, since the Al content was high, a fracture occurred during the test.

[0335] In Sample No. 860, since the P content was small, the tensile strength (TS) was low and, as a result, the B50 magnetic flux density was lower.

[0336] In Sample No. 861, since the P content was high, a fracture occurred during the test.

[0337] In Sample No. 862, since the S content was high, the W10/400 iron loss was high.

[0338] In Sample No. 863, since the Mg content was high, the W10/400 iron loss was high.

[0339] In Sample No. 864, since the average grain size was large, the tensile strength (TS) and the total elongation EL were low and the W10/400 iron loss was high.

Ninth Test

[0340] In a ninth test, cast steel having the chemical composition shown in Table 17 was cast to produce a plate, and the plate was hot-rolled to obtain a steel strip having a proportion of columnar crystals of 80% or more in terms of area fraction and an average grain size of 0.1 mm or more.

[0341] Then, the steel strip was subjected to cold rolling, final annealing and Cu precipitation treatment, through which several non-oriented electrical steel sheets were produced that have thicknesses of 0.20 mm and 0.65 mm mm. Cold rolling was carried out at a cold rolling temperature of 50°C with a cold rolling reduction of 80%, and in the final annealing, the steel strip was heated at a temperature rise rate of 20°C /s and, after 1000°C is reached, immersed for 15 seconds and cooled in air. Furthermore, as a Cu precipitation treatment, the steel sheet was heated to 600°C, immersed for 1 minute and then cooled in air. In Sample No. 912, the Cu precipitation treatment was omitted. For each of the unoriented electrical steel sheets, the number of elemental Cu particles of less than 100 nm per 10 μm2, the crystal orientation intensity I {100} and the average grain size r were measured. The results are shown in Table 18.

[0342] Then, the magnetic characteristics and mechanical properties of each of the unoriented electrical steel sheets were measured. For this measurement, a ring specimen having an outside diameter of 5 inches (12.70 cm) and an inside diameter of 4 inches (10.16 cm) was used. That is, a ring magnetism measurement was taken. The results are shown in Table 18. A W10/400 iron loss equal to or less than an endpoint W0 (W/kg) represented by Formula 2 indicates an excellent value. That is, in the case where the thickness was 0.20 mm, an iron loss of 11.0 (W/kg) or less was rated as excellent, and in the case where the thickness was 0.65 mm, a loss iron of 46.7 (W/kg) or less was rated as excellent. A B50 magnetic flux density of 1.63 T or greater has been rated as excellent. W0 = 11 x [0.45 + 0.55 x {0.5 x (t/0.20) + 0.5 x (t/0.20)2}] (Formula 2)

[0343] In this document, the mechanical properties were tested using the method described in the JIS standard. The specimen used was a JIS No. 5 specimen, in which a parallel portion of the specimen was aligned with the rolling direction of the steel sheet.

[0344] In particular, for an unoriented electrical steel sheet used in an HEV motor to withstand a u-high rotational speed of nearly 10,000 rpm, TS > 590 MPa and EL > 10% were considered good criteria. Table 17 Table 18

[0345] As shown in Tables 17 and 18, in Samples Nos. 901 to 910 and 914 to 916, since the chemical composition was within the range of the present invention and the other conditions were within the range of the present invention, good results were obtained for magnetic characteristics and mechanical properties.

[0346] In Sample No. 911, since practically no element forming coarse precipitates was contained, the loss of iron W10/400 was high.

[0347] In Sample No. 912, since the Cu content was very small, the tensile strength (TS) was insufficient.

[0348] In Sample No. 913, since the Cu content was very high, a fracture occurred during the test.

[0349] In Sample No. 917, since the plate thickness was very thick, the W10/400 iron loss was high.

Tenth Test

[0350] In a tenth test, molten steel having the chemical composition shown in Table 19 was melted to produce a plate, and the plate was hot-rolled to obtain a steel strip having a proportion of columnar crystals of 80% or more in terms of area fraction and an average grain size of 0.1 mm or more. The remainder is Fe and impurities. Then, the steel strip was subjected to cold rolling, final annealing and Cu precipitation treatment, whereby various unoriented electrical steel sheets having a thickness of 0.20 mm were produced. At this point, by changing the manufacturing conditions in various ways, unoriented electrical steel sheets have been produced that have different strengths of crystal orientation. For each of the unoriented electrical steel sheets, the number of elemental Cu particles of less than 100 nm per 10 μm2, the crystal orientation intensity I {100} and the average grain size r were measured. The results are shown in Table 20.

[0351] In addition, the W10/400 iron loss, the B50 magnetic flux density, the tensile strength (TS) and the total elongation (EL) were also measured using the same procedure as in the ninth test. The results are shown in Table 20. Table 19 Table 20

[0352] As shown in Tables 19 and 20, in Samples Nos. 923 to 928, since the chemical composition was within the range of the present invention and the other conditions were within the range of the present invention, good results were obtained for the characteristics magnetic and mechanical properties.

[0353] In Samples Nos. 921 and 922, since the Ni content was very small, the total elongation (EL) was insufficient.

[0354] In Sample No. 929, since the Ni content was too large, the total elongation (EL) was insufficient.

[0355] In Samples Nos. 930 to 938, since the orientation intensity of crystal {100} I was too low, the magnetic flux density B50 was insufficient.

[0356] In Samples Nos. 939 to 947, since substantially no coarse precipitate-forming elements were contained, the iron loss W10/400 was deteriorated.

[0357] In Samples Nos. 948 to 956, since the Cu content was very small, the tensile strength (TS) was insufficient.

[0358] In Samples Nos 957 to 965, since the Cu content was very small and the crystal orientation intensity I {100} was very low, the tensile strength (TS) and magnetic flux density B50 were insufficient.

[0359] In Samples Nos. 966 to 974, since practically no elements forming coarse precipitates were contained and the Cu content was very small, the W10/400 iron loss was deteriorated and the tensile strength (TS) was insufficient .

Industrial Applicability

[0360] According to the present invention, it is possible to provide an unoriented electrical steel sheet that has excellent magnetic characteristics and excellent strength and elongation. Therefore, the present invention has high industrial utility value. v

Claims (3)

1. Unoriented electrical steel sheet comprising, as a chemical composition, by weight %: C: 0.0030% or less; Si: 2.00% to 4.00%; Al: 0.01% to 3.00%; Mn: 0.10% to 2.00%; P: 0.005% to 0.200%; S: 0.0030% or less; Cu: more than 1.0% and 3.0% or less; Ni: 0.10% to 3.0%; one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd: more than 0.0005% and 0.0100% or less in total; a Q parameter represented by Formula 1 where the Si content (% by mass) is defined as [Si], the Al content (% by mass) is defined as [Al] and the Mn content (% by mass) is set to [Mn]: 2.00 or more; Sn: 0.00% to 0.40%; Cr: 0.0% to 10.0% and the rest: Fe and impurities, characterized by the fact that the number of particles of an elemental Cu that have a diameter of less than 100 nm is 5 or more per 10 μm2, the crystal orientation intensity {100} is 2.4 or more, the thickness is 0.10 mm to 0.60 mm, and the average grain size is 70 μm to 200 μm Q = [Si] +2 [ Al] - [Mn] (Formula 1). 2. Non-oriented electrical steel sheet, according to claim 1, characterized by the fact that, in the chemical composition, Sn: 0.02% to 0.40% is satisfied. 3. Non-oriented electrical steel sheet, according to claim 1 or 2, characterized by the fact that, in the chemical composition, Cr: 0.2% to 10.0% is satisfied.