NON-ORIENTED ELECTRICAL STEEL SHEET, CORE, COLD-ROLLED STEEL SHEET, METHOD FOR MANUFACTURING NON-ORIENTED ELECTRICAL STEEL SHEET, AND METHOD FOR MANUFACTURING COLD-ROLLED STEEL SHEET

Abstract

A non-oriented electrical steel sheet has a predetermined chemical composition. The chemical composition satisfies (2×[Mn]+2.5×[Ni]+[Cu])−([Si]+2×[sol.Al]+4×[P])≥1.50%. In a case where Ahkl-uvw represents the area ratio of crystal grains in an {hkl}<uvw> orientation to the entire visual field when a plane at a depth of ½ of a sheet thickness from a surface parallel to a rolled surface is measured by SEM-EBSD, A411-011 is 15.0% or more, and the average grain size is 50 μm to 150 μm.

Claims

1. A non-oriented electrical steel sheet comprising, as a chemical composition, by mass %: C: 0.0100% or less; Si: 1.50% to 4.00%; sol.Al: 0.0001% to 1.00%; S: 0.0100% or less; N: 0.0100% or less; one or more selected from the group consisting of Mn, Ni, and Cu: 2.5% to 5.0% in total; Co: 0% to 1.0%; Sn: 0% to 0.40%; Sb: 0% to 0.40%; P: 0% to 0.400%; one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0% to 0.010% in total; and a remainder of Fe and impurities, wherein the following Equation (1) is satisfied, where, by mass %, a Mn content is [Mn], a Ni content is [Ni], a Cu content is [Cu], a Si content is [Si], a sol.Al content is [sol.Al], and a P content is [P], in a case where Ahkl-uvw represents an area ratio of crystal grains in an {hkl}<uvw> orientation to an entire visual field when a plane at a depth of ½ of a sheet thickness from a surface parallel to a rolled surface is measured by SEM-EBSD, A411-011 is 15.0% or more, and an average grain size is 50 μm to 150 μm,
(2×[Mn]+2.5×[Ni]+[Cu])−([Si]+2×[sol.Al]+4×[P])≥1.50%  (1).

2. The non-oriented electrical steel sheet according to claim 1, wherein when the surface is measured by the SEM-EBSD to create an ODF at φ2=45°, the non-oriented electrical steel sheet has a maximum intensity at φ1=0° to 10° among φ1=0° to 90° and Φ=20°, and has a maximum intensity at Φ=5° to 35° among φ1=0° and Φ=0° to 90°.

3. The non-oriented electrical steel sheet according to claim 1 or 2, wherein an area ratio of a specific orientation to the entire visual field when the plane at the depth of ½ of the sheet thickness from the surface parallel to the rolled surface is measured by the SEM-EBSD satisfies both the following Equations (2) and (3),
A411-011/A411-148≥1.1  (2)
A411-011/A100-011≥2.0  (3)

4. A non-oriented electrical steel sheet comprising, as a chemical composition, by mass %: C: 0.0100% or less; Si: 1.50% to 4.00%; sol.Al: 0.0001% to 1.00%; S: 0.0100% or less; N: 0.0100% or less; one or more selected from the group consisting of Mn, Ni, and Cu: 2.5% to 5.0% in total; Co: 0% to 1.0%; Sn: 0% to 0.40%; Sb: 0% to 0.40%; P: 0% to 0.400%; one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0% to 0.010% in total; and a remainder of Fe and impurities, wherein the following Equation (1) is satisfied, where, by mass %, a Mn content is [Mn], a Ni content is [Ni], a Cu content is [Cu], a Si content is [Si], a sol.Al content is [sol.Al], and a P content is [P], an area ratio A.sub.sα of crystal grains having a crystal orientation of an α-fiber to an entire visual field when a plane at a depth of ½ of a sheet thickness from a surface parallel to a rolled surface is measured by SEM-EBSD is 20.0% or more, an ODF intensity in a {100}<011> orientation when the surface is measured by the SEM-EBSD to create an ODF is 15.0 or less, and when Gs is set as a number average value of GOS with respect to the entire visual field when the surface is measured by the SEM-EBSD, the Gs is 0.8 or more and 3.0 or less,
(2×[Mn]+2.5×[Ni]+[Cu])−([Si]+2×[sol.Al]+4×[P])≥1.50%  (1).

5. A core comprising the non-oriented electrical steel sheet according to claim 1 or 2.

6. A core comprising the non-oriented electrical steel sheet according to claim 4.

7. A cold-rolled steel sheet which is used for manufacturing the non-oriented electrical steel sheet according to claim 1 or 2, the cold-rolled steel sheet comprising, as a chemical composition, by mass %: C: 0.0100% or less; Si: 1.50% to 4.00%; sol.Al: 0.0001% to 1.00%; S: 0.0100% or less; N: 0.0100% or less; one or more selected from the group consisting of Mn, Ni, and Cu: 2.5% to 5.0% in total; Co: 0% to 1.0%; Sn: 0% to 0.40%; Sb: 0% to 0.40%; P: 0% to 0.400%; one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0% to 0.010% in total; and a remainder of Fe and impurities, wherein the following Equation (1) is satisfied, where, by mass %, a Mn content is [Mn], a Ni content is [Ni], a Cu content is [Cu], a Si content is [Si], a sol.Al content is [sol.Al], and a P content is [P], and an area ratio A.sub.sα of crystal grains having a crystal orientation of an α-fiber to an entire visual field when a plane at a depth of ½ of a sheet thickness from a surface parallel to a rolled surface is measured by SEM-EBSD is 15.0% or more,
(2×[Mn]+2.5×[Ni]+[Cu])−([Si]+2×[sol.Al]+4×[P])≥1.50%  (1).

8. A method for manufacturing a non-oriented electrical steel sheet, the method comprising: a hot rolling step of performing hot rolling on a steel material so that a final pass of finish rolling is performed at an Ar3 temperature or higher to obtain a hot-rolled steel sheet, the steel material including, as a chemical composition, by mass %: C: 0.0100% or less, Si: 1.50% to 4.00%, sol.Al: 0.0001% to 1.00%, S: 0.0100% or less, N: 0.0100% or less, one or more selected from the group consisting of Mn, Ni, and Cu: 2.5% to 5.0% in total, Co: 0% to 1.0%, Sn: 0% to 0.40%, Sb: 0% to 0.40%, P: 0% to 0.400%, one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0% to 0.010% in total, and a remainder of Fe and impurities, in which the following Equation (1) is satisfied, where, by mass %, a Mn content is [Mn], a Ni content is [Ni], a Cu content is [Cu], a Si content is [Si], a sol.Al content is [sol.Al], and a P content is [P]; a cooling step of cooling the hot-rolled steel sheet after the hot rolling step; a cold rolling step of performing cold rolling on the hot-rolled steel sheet after the cooling step to obtain a cold-rolled steel sheet; an intermediate annealing step of performing intermediate annealing on the cold-rolled steel sheet; a skin pass rolling step of performing skin pass rolling on the cold-rolled steel sheet after the intermediate annealing step to obtain the non-oriented electrical steel sheet; and a final annealing step of performing final annealing on the non-oriented electrical steel sheet after the skin pass rolling step at an annealing temperature of 750° C. or higher and an Ac1 temperature or lower and at an annealing time of 2 hours or longer, wherein in the cooling step, the cooling is started after 0.10 seconds or longer have elapsed from the final pass of the finish rolling, a temperature is set to 300° C. or higher and an Ar1 temperature or lower for transformation after 3 seconds, and a rolling reduction in the skin pass rolling step is 5% to 20%,
(2×[Mn]+2.5×[Ni]+[Cu])−([Si]+2×[sol.Al]+4×[P])≥1.50%  (1).

9. A method for manufacturing a non-oriented electrical steel sheet, the method comprising: a hot rolling step of performing hot rolling on a steel material so that a final pass of finish rolling is performed at an Ar3 temperature or higher to obtain a hot-rolled steel sheet, the steel material including, as a chemical composition, by mass %: C: 0.0100% or less, Si: 1.50% to 4.00%, sol.Al: 0.0001% to 1.00%, S: 0.0100% or less, N: 0.0100% or less, one or more selected from the group consisting of Mn, Ni, and Cu: 2.5% to 5.0% in total, Co: 0% to 1.0%, Sn: 0% to 0.40%, Sb: 0% to 0.40%, P: 0% to 0.400%, one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0% to 0.010% in total, and a remainder of Fe and impurities, in which the following Equation (1) is satisfied, where, by mass %, a Mn content is [Mn], a Ni content is [Ni], a Cu content is [Cu], a Si content is [Si], a sol.Al content is [sol.Al], and a P content is [P]; a cooling step of cooling the hot-rolled steel sheet after the hot rolling step; a cold rolling step of performing cold rolling on the hot-rolled steel sheet after the cooling step to obtain a cold-rolled steel sheet; an intermediate annealing step of performing intermediate annealing on the cold-rolled steel sheet; and a skin pass rolling step of performing skin pass rolling on the cold-rolled steel sheet after the intermediate annealing step to obtain the non-oriented electrical steel sheet, wherein in the cooling step, the cooling is started after 0.10 seconds or longer have elapsed from the final pass of the finish rolling, a temperature is set to 300° C. or higher and an Ar1 temperature or lower for transformation after 3 seconds, and a rolling reduction in the skin pass rolling step is 5% to 20%,
(2×[Mn]+2.5×[Ni]+[Cu])−([Si]+2×[sol.Al]+4×[P])≥1.50%  (1).

10. The method for manufacturing a non-oriented electrical steel sheet according to claims 8 or 9, wherein in the cooling step, an average grain size of the hot-rolled steel sheet after the cooling step is 3 to 10 μm.

11. The method for manufacturing a non-oriented electrical steel sheet according to claim 8 or 9, wherein a rolling reduction in the cold rolling step is 75% to 95%.

12. The method for manufacturing a non-oriented electrical steel sheet according to claim 8 or 9, wherein in the intermediate annealing step, an annealing temperature is set to the Ac1 temperature or lower.

13. A method for manufacturing a cold-rolled steel sheet, the method comprising: a hot rolling step of performing hot rolling on a steel material so that a final pass of finish rolling is performed at an Ar3 temperature or higher to obtain a hot-rolled steel sheet, the steel material including, as a chemical composition, by mass %: C: 0.0100% or less, Si: 1.50% to 4.00%, sol.Al: 0.0001% to 1.00%, S: 0.0100% or less, N: 0.0100% or less, one or more selected from the group consisting of Mn, Ni, and Cu: 2.5% to 5.0% in total, Co: 0% to 1.0%, Sn: 0% to 0.40%, Sb: 0% to 0.40%, P: 0% to 0.400%, one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0% to 0.010% in total, and a remainder of Fe and impurities, in which the following Equation (1) is satisfied, where, by mass %, a Mn content is [Mn], a Ni content is [Ni], a Cu content is [Cu], a Si content is [Si], a sol.Al content is [sol.Al], and a P content is [P]; a cooling step of cooling the hot-rolled steel sheet after the hot rolling step; a cold rolling step of performing cold rolling on the hot-rolled steel sheet after the cooling step to obtain a cold-rolled steel sheet; and an intermediate annealing step of performing intermediate annealing on the cold-rolled steel sheet, wherein in the cooling step, the cooling is started after 0.10 seconds or longer have elapsed from the final pass of the finish rolling, a temperature is set to 300° C. or higher and an Ar1 temperature or lower for transformation after 3 seconds,
(2×[Mn]+2.5×[Ni]+[Cu])−([Si]+2×[sol.Al]+4×[P])≥1.50%  (1).

14. The method for manufacturing a cold-rolled steel sheet according to claim 13, wherein in the cooling step, an average grain size of the hot-rolled steel sheet after the cooling step is 3 to 10 μm.

15. The method for manufacturing a cold-rolled steel sheet according to claims 13 or 14, wherein a rolling reduction in the cold rolling step is 75% to 95%.

16. The method for manufacturing a cold-rolled steel sheet according to claim 13 or 14, wherein in the intermediate annealing step, an annealing temperature is set to an Ac1 temperature or lower.

17. A core comprising the non-oriented electrical steel sheet according to claim 3.

18. A cold-rolled steel sheet which is used for manufacturing the non-oriented electrical steel sheet according to claim 3, the cold-rolled steel sheet comprising, as a chemical composition, by mass %: C: 0.0100% or less; Si: 1.50% to 4.00%; sol.Al: 0.0001% to 1.00%; S: 0.0100% or less; N: 0.0100% or less; one or more selected from the group consisting of Mn, Ni, and Cu: 2.5% to 5.0% in total; Co: 0% to 1.0%; Sn: 0% to 0.40%; Sb: 0% to 0.40%; P: 0% to 0.400%; one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0% to 0.010% in total; and a remainder of Fe and impurities, wherein the following Equation (1) is satisfied, where, by mass %, a Mn content is [Mn], a Ni content is [Ni], a Cu content is [Cu], a Si content is [Si], a sol.Al content is [sol.Al], and a P content is [P], and an area ratio A.sub.sα of crystal grains having a crystal orientation of an α-fiber to an entire visual field when a plane at a depth of ½ of a sheet thickness from a surface parallel to a rolled surface is measured by SEM-EBSD is 15.0% or more,
(2×[Mn]+2.5×[Ni]+[Cu])−([Si]+2×[sol.Al]+4×[P])≥1.50%  (1).

19. A cold-rolled steel sheet which is used for manufacturing the non-oriented electrical steel sheet according to claim 4, the cold-rolled steel sheet comprising, as a chemical composition, by mass %: C: 0.0100% or less; Si: 1.50% to 4.00%; sol.Al: 0.0001% to 1.00%; S: 0.0100% or less; N: 0.0100% or less; one or more selected from the group consisting of Mn, Ni, and Cu: 2.5% to 5.0% in total; Co: 0% to 1.0%; Sn: 0% to 0.40%; Sb: 0% to 0.40%; P: 0% to 0.400%; one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0% to 0.010% in total; and a remainder of Fe and impurities, wherein the following Equation (1) is satisfied, where, by mass %, a Mn content is [Mn], a Ni content is [Ni], a Cu content is [Cu], a Si content is [Si], a sol.Al content is [sol.Al], and a P content is [P], and an area ratio A.sub.sα of crystal grains having a crystal orientation of an α-fiber to an entire visual field when a plane at a depth of ½ of a sheet thickness from a surface parallel to a rolled surface is measured by SEM-EBSD is 15.0% or more,
(2×[Mn]+2.5×[Ni]+[Cu])−([Si]+2×[sol.Al]+4×[P])≥1.50%  (1).

20. The method for manufacturing a non-oriented electrical steel sheet according to claim 10.

21. The method for manufacturing a non-oriented electrical steel sheet according to claim 10, wherein in the intermediate annealing step, an annealing temperature is set to the Ac1 temperature or lower.

22. The method for manufacturing a non-oriented electrical steel sheet according to claim 11, wherein in the intermediate annealing step, an annealing temperature is set to the Ac1 temperature or lower.

23. The method for manufacturing a non-oriented electrical steel sheet according to claim 20, wherein in the intermediate annealing step, an annealing temperature is set to the Ac1 temperature or lower.

24. The method for manufacturing a cold-rolled steel sheet according to claim 15, wherein in the intermediate annealing step, an annealing temperature is set to an Ac1 temperature or lower.

Description

EXAMPLES

[0188] Next, the non-oriented electrical steel sheet to the embodiment of the present invention will be specifically described with reference to Examples. Examples shown below are merely examples of the non-oriented electrical steel sheet according to the embodiment of the present invention, and the non-oriented electrical steel sheet according to the present invention is not limited to the following examples.

Example 1

[0189] A molten steel was cast to produce an ingot having a chemical composition shown in Table 1-1. Here, the left side of the equation represents a value on the left side in Equation (1). In addition, Mg and the like represents the total of one or more selected from the group consisting of Mg, Ca, Sr, Ba. Ce, La, Nd, Pr, Zn, and Cd. Thereafter, the produced ingot was heated to 1,150° C. hot-rolled, and finish-rolled at a finish rolling temperature FT shown in Table 1-2. Cooling was then performed under cooling conditions shown in Table 1-2 after the steel sheet has passed through the final pass (a time from when the steel sheet passes through the final pass in the finish rolling to when the cooling is started, and a temperature of the steel sheet 3 seconds later after the steel sheet has passed through the final pass).

[0190] Here, in order to examine a texture after cooling, a part of the steel sheet is cut off, and the average grain size was measured by an intercept method on a plane parallel to a rolled surface at a depth of ½ of a sheet thickness from the surface. The measurement results are shown in Table 1-2.

[0191] Next, the hot-rolled steel sheet was not annealed, and the scales were removed by pickling, and cold rolling was performed at a rolling reduction RR1 shown in Table 1-2. The intermediate annealing was then performed to be held for 30 seconds by controlling a temperature rising rate to 15.0° C./sec and controlling the intermediate annealing temperature T1 to a temperature shown in Table 1-2, in the atmosphere containing 20% hydrogen and 80% nitrogen by a volume percentage.

[0192] Here, in order to examine a texture of the cold-rolled steel sheet before the skin pass rolling, a part of the steel sheet was cut off, and a test piece of the cut steel sheet was reduced to a thickness of ½. An {hkl}<011> orientation was extracted (within a tolerance of 10°) in a measurement region of the processed surface by SEM-EBSD using OIM Analysis 7.3, and an area of the extracted orientation was divided by an area of the measurement region to obtain an α-fiber ratio A.sub.sα. The results are shown in Table 2-1.

[0193] Next, skin pass rolling was performed at a rolling reduction RR2 shown in Table 1-2.

[0194] Before the final annealing, in order to examine a texture after the skin pass rolling, a part of the steel sheet was cut off, and a test piece of the cut steel sheet was reduced to a thickness of ½. An α-fiber ratio A.sub.sα of the processed surface was obtained in the same manner as in the procedure described above. In addition, as for the ODF intensity of the {100}<011> orientation, an ODF value of the {100}<011> orientation obtained by creating an ODF under the above-described conditions using OIM Analysis 7.3 in the measurement region of the processed surface by the SEM-EBSD, and outputting data of the created ODF, was set as the ODF intensity. Furthermore, as for Gs, the number average value of the GOS value obtained by Analysis with OIM Analysis 7.3 using SEM-EBSD data was set as Gs. Each result is shown in Table 2-1.

[0195] Next, the steel sheet after the skin pass rolling was final annealed in an atmosphere of 100% hydrogen at a temperature rising rate of 100° C./hour and at the final annealing temperature T2 shown in Table 1-2. Here, a retention time at the final annealing temperature T2 was set to 2 hours.

[0196] In order to examine a texture after the final annealing, a part of the steel sheet was cut off, and a test piece of the cut steel sheet was reduced to a thickness of ½. The {411}<011> ratio, A411-011/A411-148, and A411-011/A100-011 were obtained by observation in the measurement region of the processed surface by the SEM-EBSD under the above-described measurement conditions. Further, as for φ1 (°) indicating the maximum intensity (φ1 at maximum intensity) in the {411}<uvw> orientation and ) (°) (Φ at maximum intensity) indicating the maximum intensity in the {hkl}<11> orientation, points having the maximum ODF value within a specific orientation range were set as maximum intensities of φ1 and Φ, the ODF value obtained by creating the ODF under the above-described conditions in the measurement region of the processed surface by the SE-M-EBSD using OIM Analysis 7.3, and outputting data of the created ODF. Each result is shown in Table 2-1.

[0197] Moreover, in order to examine the magnetic characteristics after the final annealing, a magnetic flux density B50 and an iron loss W10/400 were measured, and an iron loss deterioration ratio of the iron loss W10/50 under a compressive stress was obtained as an index of stress sensitivity. The magnetic flux density B50 was obtained by collecting a single plate sample for testing magnetic characteristics of a 55 mm square in two directions of 0° and 45° in the rolling direction as a measurement sample. Then, these two samples were measured to set a value in the 45° direction with respect to the rolling direction as a magnetic flux density B50 in the 45° direction and set an average value at 0°, 45° 90°, and 135° with respect to the rolling direction as a whole circumference average of the magnetic flux density B50. The iron loss W10/400 was obtained by using the above-described measurement sample collected in the 45° direction in the rolling direction. Furthermore, the iron loss deterioration ratio W.sub.x [%] of the iron loss W10/50 in the 450 direction under the compressive stress was obtained by calculating the iron loss deterioration ratio W.sub.x by the following Equation, where the iron loss W10/50 (450 direction) with no stress was set as W10/50 (0), and the iron loss W10/50 (45° direction) under the compressive stress of 10 MPa was set as W10/50 (10). The measurement results are shown in Table 2-2.

W.sub.x={W10/50(10)−W10/50(0)}/W1/50(0)

[0198] When a magnetic flux density B50 (B50 (45°) in the 45° direction with respect to the rolling direction is 1.70 T or more, the iron loss W10/400 (W100/400 (45°) in the 450 direction with respect to the rolling direction is 13.8 W/kg or less, and the iron loss deterioration ratio of W10/50 under the compressive stress in the 450 direction with respect to the rolling direction is 40% or less, it was determined that the magnetic characteristics in the 45° direction was excellent.

TABLE-US-00001 TABLE 1-1 Item Chemical Composition (Remainder of FE and Impurities) Total of Mn, Cu, Mg and C Si sol. Al S N Mn Cu Ni and Ni Co Sn Sb P The Like Left [mass [mass [mass [mass [mass [mass [mass [mass [mass [mass [mass [mass [mass [mass Side in No. %] %] %] %] %] %] %] %] %] %] %] %] %] %] Equation 101 0.0018 2.50 0.005 0.0018 0.0011 3.0 3.0 — — — 0.020 — 3.41 102 0.0018 2.50 0.005 0.0018 0.0011 3.0 3.0 — — — 0.020 — 3.41 103 0.0018 2.50 0.005 0.0018 0.0011 2.0 2.0 — — — 0.020 — 1.41 104 0.0018 2.50 0.005 0.0018 0.0011 2.0 2.0 — — — 0.020 — 1.41 105 0.0018 2.50 0.005 0.0018 0.0011 3.0 3.0 — — — 0.020 — 3.41 106 0.0009 2.50 0.07 0.0.008 0.0008 4.0 4.0 — — 0.11 0.080 — 5.04 107 0.0009 2.50 0.07 0.0008 0.0008 4.0 4.0 — — 0.11 0.080 — 5.04 108 0.0009 2.50 0.07 0.0008 0.0008 4.0 4.0 — — 0.11 0.080 — 5.04 109 0.0009 2.50 0.07 0.0008 0.0008 4.0 4.0 — — 0.11 0.080 — 5.04 110 0.0009 2.50 0.07 0.0008 0.0008 4.0 4.0 — — 0.11 0.080 — 5.04 111 0.0009 2.50 0.07 0.0008 0.0008 4.0 4.0 — — 0.11 0.080 — 5.04 112 0.0025 2.50 0.0008 0.0009 0.0025 3.1 3.1 — — — 0.035 — 3.56

TABLE-US-00002 TABLE 1-2 Item Hot Rolling Step Finish Cooling Step Transformation Point Rolling Time to Temperature Ar3 Ar1 Ac1 Temperature Start After 3 Temperature Temperature Temperature FT Cooling Seconds No. [° C.] [° C.] [° C.] [° C.] sec [° C.] 101 815 779 932 950 0.10 700 102 815 779 932 950 0.10 200 103 — 850 900 950 0.10 700 104 — 850 900 950 0.10 200 105 815 779 932 650 0.10 550 106 710 650 850 850 0.08 600 107 710 650 850 850 0.12 600 108 710 650 850 850 1.30 600 109 710 650 850 850 0.12 320 110 710 650 850 850 0.12 280 111 710 650 850 850 0.12 750 112 805 775 925 900 0.15 350 Item Cold Intermediate Skin Pass Final After Hot Rolling annealing Rolling Annealing Rolling Step Step Step Step Average Rolling Annealing Rolling Annealing Grain Reduction Temperature Reduction Temperature Size RR1 T1 RR2 T2 No. [μm] [%] [° C.] [%] [° C.] Evaluation 101 5.0 86 700 15 800 Inventive Example 102 4.2 86 700 15 800 Comparative Example 103 13.8 86 700 15 800 Comparative Example 104 11.5 86 700 15 800 Comparative Example 105 13.8 86 700 15 800 Comparative Example 106 4.9 86 700 15 800 Comparative Example 107 5.1 86 700 15 800 Inventive Example 108 5.1 86 700 15 800 Inventive Example 109 4.8 86 700 15 800 Inventive Example 110 4.5 86 700 15 800 Comparative Example 111 16.3 86 700 15 800 Comparative Example 112 4.5 93 725 13 850 Inventive Example

TABLE-US-00003 TABLE 2-1 Item Texture After Intermediate Texture After Skin Pass Texture After Final Annealing annealing {100}<011> φ1 at Φ at α-Fiber α-Fiber ODF {411}<011> {411}<uvw> {hkl}<011> A411-011/ A411-011/ Ratio A.sub.aα Ratio A.sub.sα Intensity Gs Ratio ODF max ODF max A411-148 A100-011 No. [%] [%] [—] [—] [%] [°] [°] [—] [—] 101 32.1 32.9 7.6 2.2 29.2 0 20 1.5 3.0 102 35.8 36.7 20.2  1.7 11.2 0 0 1.2 0.3 103  8.7  9.5 2.8 2.4  8.3 20 50 0.3 1.1 104 10.4 11.2 3.1 2.5  9.6 20 55 0.5 0.8 105 12.5 13.6 3.4 2.6 10.2 20 55 0.8 1.5 106 33.4 34.8 19.7  1.8 14.8 0 0 1.2 0.3 107 35.2 36.1 8.2 2.1 30.9 0 20 1.6 3.5 108 32.1 32.9 7.8 2.5 29.2 0 20 1.5 3.3 109 32.1 32.9 9.1 1.9 29.2 0 20 1.5 5.2 110 32.9 34.8 19.9  1.3 11.8 0 0 1.2 0.7 111 12.5 13.6 2.4 2.6 10.2 20 55 0.8 1.5 112 35.0 35.9 8.5 2.5 25.8 0 25 1.5 0.8

TABLE-US-00004 TABLE 2-2 Item Magnetic Characteristics Microstructure B50 Iron Loss Sheet Average (Whole B50 W10/400 Deterioration Thickness Grain Size Circumference) (45°) (45°) Ratio W.sub.x No. [mm] [μm] [T] [T] [W/kg] [%] Evaluation 101 0.30 69.2 1.64 1.75 12.9 31.3 Inventive Example 102 0.30 57.3 1.62 1.73 12.7 50.7 Comparative Example 103 0.30 70.4 1.65 1.60 14.3 54.5 Comparative Example 104 0.30 81.2 1.67 1.62 14.1 52.3 Comparative Example 105 0.30 62.4 1.66 1.61 14.5 46.2 Comparative Example 106 0.30 57.3 1.62 1.73 12.9 50.7 Comparative Example 107 0.30 69.2 1.64 1.72 13.4 30.5 Inventive Example 108 0.30 70.4 1.64 1.74 13.2 33.8 Inventive Example 109 0.30 62.5 1.64 1.75 13.1 25.7 Inventive Example 110 0.30 63.7 1.63 1.73 13.0 48.2 Comparative Example 111 0.30 62.4 1.66 1.61 14.0 46.2 Comparative Example 112 0.30 95.2 1.66 1.73 13.5 39.5 Inventive Example

[0199] Underlines in Table 1-1, Table 1-2, Table 2-1, and Table 2-2 indicate conditions deviating from the scope of the present invention.

[0200] Nos. 101, 107 to 109, and 112 of Inventive Examples had good values for all of the magnetic flux density B50 (45° direction), the iron loss W10/400, and the iron loss deterioration ratio. On the other hand, Nos. 102 and 110 of Comparative Examples had large iron loss deterioration ratios under the compressive stress because the rapid cooling was performed after the finish rolling. Nos. 103 and 104 of Comparative Examples had poor magnetic flux density B50 (450 direction), iron loss W10/400, and iron loss deterioration ratio because of a composition with a high transformation point. No. 105 of Comparative Example had poor magnetic flux density B50 (45° direction), iron loss W10/400, and iron loss deterioration ratio because the finish rolling temperature FT was lower than the Ar1 temperature. No. 106 of Comparative Example had a large iron loss deterioration ratio under the compressive stress because a time from when the steel sheet passes through the final pass in the finish rolling to when the cooling is started was too short. No. 111 of Comparative Example had poor magnetic flux density B50 (45° direction), iron loss W10/400, and iron loss deterioration ratio because a temperature in the stage until 3 seconds have elapsed after the steel sheet has passed through the final pass in the finish rolling was higher than the Ar1 temperature.

Example 2

[0201] A molten steel was cast to produce an ingot having a chemical composition shown in Table 3-1. Here, the left side of the equation represents a value on the left side in Equation (1). In addition, Mg and the like represents the total of one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd. Thereafter, the produced ingot was heated to 1,150° C., hot-rolled, and finish-rolled at a finish rolling temperature FT shown in Table 3-2. Cooling was then performed under cooling conditions shown in Table 3-2 after the steel sheet has passed through the final pass (a time from when the steel sheet passes through the final pass in the finish rolling to when the cooling is started, and a temperature of the steel sheet 3 seconds later after the steel sheet has passed through the final pass).

[0202] Here, in order to examine the texture after the cooling, an average grain size was measured by the same procedure as in Example 1. The measurement results are shown in Table 3-2.

[0203] Next, the hot-rolled steel sheet was not annealed, and the scales were removed by pickling, and cold rolling was performed at a rolling reduction RR1 shown in Table 3-2. Then, intermediate annealing was performed to be held for 30 seconds by performing the intermediate annealing in the atmosphere containing 20% hydrogen and 80% nitrogen by volume percentage and controlling the intermediate annealing temperature T1 to a temperature shown in Table 3-2.

[0204] Here, in order to examine the texture of the cold-rolled steel sheet before the skin pass rolling, an α-fiber ratio was obtained by the same procedure as in Example 1. The results are shown in Table 4-1.

[0205] Next, skin pass rolling was performed at a rolling reduction RR2 shown in Table 3-2.

[0206] Before the final annealing, in order to examine the texture after the skin pass rolling, an α-fiber ratio and Gs were obtained by the same procedure as in Example 1. Each result is shown in Table 4-1.

[0207] Next, the final annealing was performed at the final annealing temperature T2 shown in Table 3-2 in the atmosphere of 100% hydrogen. Here, a retention time at the final annealing temperature T2 was set to 2 hours.

[0208] In order to examine a texture after the final annealing, the {411}<011> ratio, the maximum intensity of φ1 and Φ. A411-011/A411-148, and A411-011/A100-011 are obtained in the same procedure as in Example 1. Each result is shown in Table 4-1.

[0209] Moreover, in order to examine the magnetic characteristics after the final annealing, a magnetic flux density B50 and an iron loss W10/400 were measured, and an iron loss deterioration ratio W.sub.x of the iron loss W10/50 under a compressive stress was obtained as an index of stress sensitivity. The measurement procedure is the same as that in Example 1. The measurement results are shown in Table 4-2.

TABLE-US-00005 TABLE 3-1 Item Chemical Composition (Remainder of Fe And Impurities) Total of Mn, Cu, Mg And C Si sol. Al S N Mn Cu Ni And Ni Co Sn Sb P The Like Left [mass [mass [mass [mass [mass [mass [mass [mass [mass [mass [mass [mass [mass [mass Side in No. %] %] %] %] %] %] %] %] %] %] %] %] %] %] Equation 201 0.0012 2.60 0.50 0.0015 0.0014 2.4 2.4 — 0.15 — 0.010 — 1.16 202 0.0012 2.60 0.50 0.0015 0.0014 2.6 2.6 — 0.15 — 0.010 — 1.56 203 0.0012 2.60 0.50 0.0015 0.0014 4.4 4.4 — 0.15 — 0.010 — 5.16 204 0.0012 2.60 0.50 0.0015 0.0014 5.2 5.2 — 0.15 — 0.010 — 6.76 205 0.0012 2.50 0.50 0.0015 0.0014 2.5 2.5 — 0.15 — 0:010 — 1.48 206 0.0012 3.00 0.50 0.0015 0.0014 3.5 3.5 — 0.15 — 0.010 — 2.96 207 0.0012 3.00 1.00 0.0015 0.0014 3.0 3.0 — 0.15 — 0.010 — 0.98 208 0.0012 1.00 0.01 0.0015 0.0014 2.5 2.5 — 0.15 — 0.010 — 3.95 209 0.0012 2.40 0.12 0.0015 0.0014 2.4 0.2 2.6 — 0.15 — 0.010 — 2.62 210 0.0012 2.40 0.12 0.0015 0.0014 0.2 2.4 2.6 — 0.15 — 0.010 — 3.72 211 0.0012 2.40 0.12 0.0015 0.0014 2.5 2.5 0.2 0.15 — 0.010 — 2.12 212 0.0012 2.40 0.12 0.0015 0.0014 2.4 0.2 2.6 — 0.15 — 0.010 — 2.32 213 0.0012 3.10 1.00 0.0015 0.0014 0.2 2.4 2.6 — 0.15 — 0.010 — −2.34  

TABLE-US-00006 TABLE 3-2 Item Hot Rolling Step Finish Cooling Step Transformation Point Rolling Time to Temperature Ar3 Ar1 Ac1 Temperature Start After 3 Temperature Temperature Temperature FT Cooling Seconds No. [° C.] [° C.] [° C.] [° C.] sec [° C.] 201 — 900 980 950 0.50 700 202 880 804 975 950 0.50 400 203 730 657 869 950 0.50 400 204 710 603 814 950 0.50 400 205 — 890 970 950 0.50 400 206 840 742 911 950 0.50 400 207 — — — 950 0.50 400 208 820 701 899 950 0.50 400 209 830 751 924 950 0.50 400 210 805 708 904 950 0.50 400 211 890 798 966 950 0.50 400 212 870 762 933 950 0.50 400 213 — — — 950 0.50 400 Item Cold Intermediate Skin Pass Final After Hot Rolling annealing Rolling Annealing Rolling Step Step Step Step Average Rolling Annealing Rolling Annealing Grain Reduction Temperature Reduction Temperature Size RR1 T1 RR2 T2 No. [μm] [%] [° C.] [%] [° C.] Evaluation 201 13.4 86 700 15 800 Comparative Example 202 5.0 86 700 15 800 Inventive Example 203 5.2 86 700 15 800 Inventive Example 204 5.3 86 700 15 800 Comparative Example 205 12.4 86 700 15 800 Comparative Example 206 5.0 86 700 15 800 Inventive Example 207 12.8 86 700 15 800 Comparative Example 208 5.2 86 700 51 800 Comparative Example 209 5.2 86 700 15 800 Inventive Example 210 5.1 86 700 15 800 Inventive Example 211 4.8 86 700 15 800 Inventive Example 212 5.5 86 700 15 800 Inventive Example 213 12.3 86 700 51 800 Comparative Example

TABLE-US-00007 TABLE 4-1 Item Texture After Intermediate Texture After Skin Pass Texture After Final Annealing annealing {100}<011> φ1 at Φ at α-Fiber α-Fiber ODF {411}<011> {411}<uvw> {hkl}<011> A411-011/ A411-011/ Ratio A.sub.aα Ratio A.sub.sα Intensity Gs Ratio ODF max ODF max A411/148 A100-011 No. [%] [%] [—] [—] [%] [°] [°] [—] [—] 201  7.2  8.9 2.4 2.5  7.3 20 55 0.4 1 202 27.4 28.1 7.7 2.0 27.3 0 20 1.4 2.7 203 32.1 32.9 8.3 2.2 29.2 0 20 1.5 3.0 204 30.4 31.1 8.1 2.3 28.6 0 20 1.3 2.9 205  8.2  9.1 2.7 2.6  6.2 20 50 0.3 0.9 206 30.9 32.0 8.5 2.0 28.2 0 20 1.7 4.9 207  6.8  7.8 2.7 2.5  6.7 20 55 0.4 0.9 208 31.2 32.2 8.0 2.1 27.5 0 20 1.6 4.6 209 41.7 42.0 10.2 2.3 28.4 0 20 1.4 4.2 210 27.4 28.1 7.1 2.0 27.3 0 20 1.4 2.7 211 35.4 36.1 9.4 2.1 30.1 0 20 1.7 4.1 212 27.4 28.1 7.3 2.0 27.3 0 20 1.4 2.7 213  8.2  9.1 2.4 2.6  6.2 20 50 0.3 0.9

TABLE-US-00008 TABLE 4-2 Item Magnetic Characteristics Microstructure B50 Iron Loss Sheet Average (Whole B50 W10/400 Deterioration Thickness Grain Size Circumference) (45°) (45°) Ratio W.sub.x No. [mm] [μm] [T] [T] [W/kg] [%] Evaluation 201 0.30 80.4 1.65 1.58 14.5 52.9 Comparative Example 202 0.30 78.1 1.61 1.70 13.3 30.4 Inventive Example 203 0.30 69.2 1.62 1.72 13.0 33.2 Inventive Example 204 0.30 64.8 1.51 1.48 13.2 31.9 Comparative Example 205 0.30 80.4 1.65 1.57 14.4 51.3 Comparative Example 206 0.30 66.9 1.64 1.73 13.3 29.9 Inventive Example 207 0.30 67.2 1.66 1.55 14.7 51.9 Comparative Example 208 0.30 71.1 1.67 1.74 15.4 30.1 Comparative Example 209 0.30 70.1 1.65 1.74 13.2 28.9 Inventive Example 210 0.30 78.1 1.61 1.70 13.3 30.4 Inventive Example 211 0.30 68.8 1.63 1.71 13.4 29.4 Inventive Example 212 0.30 78.1 1.61 1.70 13.3 30.4 Inventive Example 213 0.30 80.4 1.65 1.57 14.5 51.3 Comparative Example

[0210] Underlines in Table 3-1, Table 3-2, Table 4-1, and Table 4-2 indicate conditions deviating from the scope of the present invention.

[0211] Nos. 202, 203, 206, and 209 to 212 of Inventive Examples had good values for all of the magnetic flux density B50 in the 45° direction, the iron loss W10/400, and the iron loss deterioration ratio.

[0212] On the other hand, Nos. 201 and 205 of Comparative Examples had poor magnetic flux density B50 (45° direction), iron loss W10/400 (450 direction), and iron loss deterioration ratio because of a composition with a high transformation point, and Nos. 207 and 213 had poor magnetic flux density B50 (45° direction), iron loss W10/400 (45° direction), and iron loss deterioration ratio because they had a composition in which α-γ transformation does not occur. No. 204 of Comparative Example had high costs and poor magnetic flux density B50 (45° direction) because it excessively contained Mn. No. 208 of Comparative Example had poor iron loss W10/400 (45° direction) because the Si content was insufficient.

Example 3

[0213] A molten steel was cast to produce an ingot having a chemical composition shown in Table 5-1. Here, the left side of the equation represents a value on the left side in Equation (1). In addition, Mg and the like represents the total content of one or more selected from the group consisting of Mg, Ca. Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd.

[0214] Thereafter, the produced ingot was heated to 1,150° C., hot-rolled, and finish-rolled at a finish rolling temperature FT shown in Table 5-2. Cooling was then performed under cooling conditions shown in Table 5-2 after the steel sheet has passed through the final pass (a time from when the steel sheet passes through the final pass in the finish rolling to when the cooling is started, and a temperature of the steel sheet 3 seconds later after the steel sheet has passed through the final pass).

[0215] Here, in order to examine the texture after the cooling, an average grain size was measured by the same procedure as in Example 1. The measurement results are shown in Table 5-2.

[0216] Next, the hot-rolled steel sheet was not annealed, and the scales were removed by pickling, and cold rolling was performed at a rolling reduction RR1 shown in Table 5-2. Then, intermediate annealing was performed to be held for 30 seconds by performing the intermediate annealing in the atmosphere containing 20% hydrogen and 80% nitrogen by a volume percentage and controlling the intermediate annealing temperature T1 to a temperature shown in Table 5-2.

[0217] Here, in order to examine the texture of the cold-rolled steel sheet before the skin pass rolling, an α-fiber ratio was obtained by the same procedure as in Example 1. The results are shown in Table 6-1.

[0218] Next, skin pass rolling was performed at a rolling reduction RR2 shown in Table 5-2.

[0219] Before the final annealing, in order to examine the texture after the skin pass rolling, an α-fiber ratio and Gs were obtained by the same procedure as in Example 1. Each result is shown in Table 6-1.

[0220] Next, the final annealing was performed at the final annealing temperature T2 shown in Table 5-2 in the atmosphere of 100% hydrogen. Here, a retention time at the final annealing temperature T2 was set to 2 hours.

[0221] In order to examine a texture after the final annealing, the {411}<011> ratio, the maximum intensity of φ1 and Φ, A411-011/A411-148, and A411-011/A100-011 were obtained in the same procedure as in Example 1. Each result is shown in Table 6-1.

[0222] Moreover, in order to examine the magnetic characteristics after the final annealing, a magnetic flux density B50 and an iron loss W10/400 were measured, and an iron loss deterioration ratio W.sub.x of the iron loss W10/50 under a compressive stress was obtained as an index of stress sensitivity. The measurement procedure is the same as that in Example 1. The measurement results are shown in Table 6-2.

TABLE-US-00009 TABLE 5-1 Item Chemical Composition (Remainder of Fe And Impurities) Total of Mn, Cu, Mg And C Si sol. Al S N Mn Cu Ni And Ni Co Sn Sb P The Like Left [mass [mass [mass [mass [mass [mass [mass [mass [mass [mass [mass [mass [mass [mass Side in No. %] %] %] %] %] %] %] %] %] %] %] %] %] %] Equation 301 0.0022 3.43 0.02 0.0042 0.0023 3.7 3.7 — — — 0.006 Mg: 0.005 3.91 302 0.0022 3.43 0.02 0.0042 0.0023 3.7 3.7 — — — 0.006 Mg: 0.005 3.91 303 0.0022 3.43 0.02 0.0042 0.0023 3.7 3.7 — — — 0.006 Mg: 0.005 3.91 304 0.0022 3.43 0.02 0.0042 0.0023 3.7 3.7 — — — 0.006 Mg: 0.005 3.91 305 0.0022 3.43 0.02 0.0042 0.0023 3.7 3.7 — — — 0.006 Mg: 0.005 3.91 306 0.0022 3.43 0.02 0.0042 0.0023 3.7 3.7 — — — 0.006 Mg: 0.005 3.91 307 0.0022 3.43 0.95 0.0042 0.0023 2.2 2.2 — — — 0.006 Mg: 0.005 −0.95   308 0.0022 3.43 0.95 0.0042 0.0023 2.2 2.2 — — — 0.006 Mg: 0.005 −0.95   309 0.0022 3.43 0.95 0.0042 0.0023 2.9 2.9 — — — 0.006 Mg: 0.005 0.45 310 0.0022 3.43 0.95 0.0042 0.0023 2.9 2.9 — — — 0.006 Mg: 0.005 0.45 311 0.0022 2.20 0.10 0.0042 0.0023 2.4 2.4 — — — 0.006 Mg: 0.005 2.38 312 0.0022 2.20 0.10 0.0042 0.0023 2.4 2.4 — — — 0.006 Mg: 0.005 2.38 313 0.0013 3.10 0.30 0.0021 0.0011 3.5 3.5 — — — 0.100  Mg: 0.002, 2.90  Pr: 0.002 315 0.0013 3.10 0.30 0.0021 0.0011 3.5 3.5 — — — 0.100 .sup. Sr: 0.002, 2.90  Cd: .0002 316 0.0013 3.10 0.30 0.0021 0.0011 3.5 3.5 — — — 0.100  Ba: 0.002, 2.90  Zn: 0.002 317 0.0013 3.10 0.30 0.0021 0.0011 3.5 3.5 — — — 0.100  .sup. La: 0.002, 2.90 .sup. Nd: 0.002 318 0.0013 3.10 0.30 0.0021 0.0011 3.5 3.5 — — — 0.100  Ca: 0.004, 2.90  Ce: 0.004

TABLE-US-00010 TABLE 5-2 Item Hot Rolling Step Finish Cooling Step Transformation Point Rolling Time to Temperature Ar3 Ar1 Ac1 Temperature Start After 3 Temperature Temperature Temperature FT Cooling Seconds No. [° C.] [° C.] [° C.] [° C.] sec [° C.] 301 795 699 897 950 0.10 650 302 795 699 897 950 0.10 650 303 795 699 897 950 0.10 650 304 795 699 897 950 0.10 650 305 795 699 897 950 0.10 650 306 795 699 897 950 0.10 650 307 950 0.10 650 308 950 0.10 650 309 950 0.10 650 310 950 0.10 650 311 870 765 936 950 0.10 650 312 870 765 936 950 0.10 650 313 840 745 913 950 0.10 700 315 840 745 913 950 0.10 700 316 840 745 913 950 0.10 700 317 840 745 913 950 0.10 700 318 840 745 913 950 0.10 700 Item Cold Intermediate Skin Pass Final After Hot Rolling annealing Rolling Annealing Rolling Step Step Step Step Average Rolling Annealing Rolling Annealing Grain Reduction Temperature Reduction Temperature Size RR1 T1 RR2 T2 No. [μm] [%] [° C.] [%] [° C.] Evaluation 301 5.5 86 700  0 800 Comparative Example 302 5.5 86 700  4 800 Comparative Example 303 5.5 86 700  6 800 Inventive Example 304 5.5 86 700 13 800 Inventive Example 305 5.5 86 700 18 800 Inventive Example 306 5.5 86 700 22 800 Comparative Example 307 12.8 86 700  0 800 Comparative Example 308 12.8 86 700 13 800 Comparative Example 309 11.5 86 700  0 800 Comparative Example 310 11.5 86 700 13 800 Comparative Example 311 5.2 86 700  0 800 Comparative Example 312 5.2 86 700 13 800 Comparative Example 313 5.0 86 700 15 800 Inventive Example 315 5.0 86 700 15 800 Inventive Example 316 5.0 86 700 15 800 Inventive Example 317 5.0 86 700 15 800 Inventive Example 318 5.0 86 700 15 800 Inventive Example

TABLE-US-00011 TABLE 6-1 Item Texture After Intermediate Texture After Skin Pass Texture After Final Annealing annealing {100}<011> φ1 at Φ at α-Fiber α-Fiber ODF {411}<011> {411}<uvw> {hkl}<011> A411-011/ A411-011/ Ratio A.sub.aα Ratio A.sub.sα Intensity Gs Ratio ODF max ODF max A411-148 A100-011 No. [%] [%] [—] [—] [%] [°] [°] [—] [—] 301 32.1 32.1 8.8 0.2 12.4 20 20 0.8 1.5 302 32.1 32.5 8.9 0.7 25.4 0 20 1.4 2.8 303 32.1 32.9 9.2 1.1 31.6 0 20 1.7 4.9 304 32.1 33.5 9.5 1.5 29.2 0 20 1.5 3.0 305 32.1 33.0 9.3 2.5 28.4 0 20 1.4 4.2 306 32.1 28.9 6.4 3.1 13.2 0 40 1.1 6.9 307  6.8  6.8 2.1 0.3  6.7 20 55 0.4 0.9 308  6.8  7.3 3.1 1.7  6.2 20 50 0.7 1.0 309  8.3  8.3 2.8 0.2  8.1 20 55 0.6 1.0 310  8.3 10.5 3.3 1.7  9.5 20 50 0.8 1.1 311 31.2 31.2 6.9 0.2 11.2 20 20 0.9 1.7 312 31.2 32.2 7.7 2.1 27.5 0 20 1.6 4.6 313 29.8 30.4 6.8 1.7 30.2 0 20 1.5 3.5 315 30.1 31.1 6.7 1.6 31.5 0 20 1.6 3.7 316 29.3 33.4 6.5 1.6 34.8 0 20 1.8 3.9 317 30.0 31.5 6.8 1.7 32.1 0 20 1.7 3.4 318 28.8 29.8 7.3 1.7 30.8 0 20 1.5 3.9

TABLE-US-00012 TABLE 6-2 Item Magnetic Characteristics Microstructure B50 Iron Loss Sheet Average (Whole B50 W10/400 Deterioration Thickness Grain Size Circumference) (45°) (45°) Ratio W.sub.x No. [mm] [μm] [T] [T] [W/kg] [%] Evaluation 301 0.30 32.1 1.58 1.60 14.3 52.1 Comparative Example 302 0.30 44.5 1.60 1.68 14.1 33.4 Comparative Example 303 0.30 66.9 1.63 1.73 13.1 26.7 Inventive Example 304 0.30 69.2 1.64 1.75 13.1 32.7 Inventive Example 305 0.30 70.1 1.64 1.74 13.5 28.5 Inventive Example 306 0.30 71.7 1.57 1.63 14.4 33.5 Comparative Example 307 0.30 46.7 1.60 1.55 14.7 51.9 Comparative Example 308 0.30 66.7 1.58 1.54 15.0 50.7 Comparative Example 309 0.30 48.4 1.61 1.57 14.5 50.3 Comparative Example 310 0.30 59.7 1.61 1.59 14.5 49.1 Comparative Example 311 0.30 40.2 1.58 1.63 14.3 45.7 Comparative Example 312 0.30 71.1 1.67 1.74 15.4 30.1 Comparative Example 313 0.30 70.8 1.60 1.71 13.6 30.4 Inventive Example 315 0.30 73.1 1.61 1.72 13.3 29.8 Inventive Example 316 0.30 70.3 1.62 1.72 13.0 28.6 Inventive Example 317 0.30 75   1.61 1.71 13.5 30.1 Inventive Example 318 0.30 76.5 1.61 1.72 13.1 30.2 Inventive Example

[0223] Underlines in Table 5-1. Table 5-2. Table 6-1, and Table 6-2 indicate conditions deviating from the scope of the present invention.

[0224] Nos. 303 to 305 and 313 to 318 of Inventive Examples had good values for all of the magnetic flux density B50 in the 45° direction, the iron loss W10/400, and the iron loss deterioration ratio.

[0225] On the other hand, No. 301 of Comparative Example was manufactured by the same process as Nos. 303 to 305 of inventive steels until the intermediate annealing, and in a state before the skin pass, it was a cold-rolled steel sheet corresponding to Claim 7 which is an embodiment of the present invention, but was not subjected to the skin pass rolling. Therefore, No. 301 of Comparative Example had poor magnetic flux density B50 (45° direction), iron loss W10/400 (45° direction), and iron loss deterioration ratio. Similarly to No. 301 described above, No. 302 of Comparative Example was a cold-rolled steel sheet corresponding to Claim 7 which is an embodiment of the present invention in a state before the skin pass, but it had a very small rolling reduction RR2 in the skin pass rolling. Therefore, the obtained non-oriented electrical steel sheet had poor iron loss W10/400 (45° direction). Similarly to Nos. 301 and 302 described above, No. 306 of Comparative Example was a cold-rolled steel sheet corresponding to Claim 7 which is an embodiment of the present invention in a state before the skin pass rolling, but it had a very large rolling reduction RR2 in the skin pass. Therefore, the obtained non-oriented electrical steel sheet had poor magnetic flux density B50 (45° direction) and iron loss W10/400 (45° direction). Nos. 307 to 310 of Comparative Examples had poor magnetic flux density B50 (45° direction), iron loss W10/400 (45° direction), and iron loss deterioration ratio because they had a composition in which α-γ transformation does not occur. No. 311 of Comparative Example had poor magnetic flux density B50 (450 direction), iron loss W10/400 (45° direction), and iron loss deterioration ratio because Mn and the like (one or more of Mn, Cu, and Ni) was insufficient and the skin pass rolling was not performed. No. 312 of Comparative Example had poor iron loss W10/400 (45° direction) because Mn and the like was insufficient.

Example 4

[0226] A molten steel was cast to produce an ingot having a chemical composition shown in Table 7-1. Here, the left side of the equation represents a value on the left side in Equation (1). In addition, Mg and the like represents the total of one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd. Thereafter, the produced ingot was heated to 1,150° C., hot-rolled, and finish-rolled at a finish rolling temperature FT shown in Table 7-2. Cooling was then performed under cooling conditions shown in Table 7-2 after the steel sheet has passed through the final pass (a time from when the steel sheet passes through the final pass in the finish rolling to when the cooling is started, and a temperature of the steel sheet 3 seconds later after the steel sheet has passed through the final pass).

[0227] Here, in order to examine the texture after the cooling, an average grain size was measured by the same procedure as in Example 1. The measurement results are shown in Table 7-2.

[0228] Next, the hot-rolled steel sheet was not annealed, and the scales were removed by pickling, and cold rolling was performed at a rolling reduction RR1 shown in Table 7-2. Then, intermediate annealing was performed to be held for 30 seconds by performing the intermediate annealing in the atmosphere containing 20% hydrogen and 80% nitrogen by a volume percentage and controlling the intermediate annealing temperature T1 to a temperature shown in Table 7-2.

[0229] Here, in order to examine the texture of the cold-rolled steel sheet before the skin pass rolling, an α-fiber ratio was obtained by the same procedure as in Example 1. The results are shown in Table 8-1.

[0230] Next, skin pass rolling was performed at a rolling reduction RR2 shown in Table 7-2.

[0231] Before the final annealing, in order to examine the texture after the skin pass rolling, an α-fiber ratio and Gs were obtained by the same procedure as in Example 1. Each result is shown in Table 8-1.

[0232] Next, the final annealing was performed at the final annealing temperature T2 shown in Table 7-2 in the atmosphere of 100% hydrogen. Here, a retention time at the final annealing temperature T2 was set to 2 hours.

[0233] In order to examine a texture after the final annealing, the {411}<011> ratio, the φ1 and Φ at maximum intensity, A411-011/A411-148, and A411-011/A100-011 are obtained in the same procedure as in Example 1. Each result is shown in Table 8-1.

[0234] Moreover, in order to examine the magnetic characteristics after the final annealing, a magnetic flux density B50 and an iron loss W10/400 were measured, and an iron loss deterioration ratio W.sub.x of the iron loss W10/50 under a compressive stress was obtained as an index of stress sensitivity. The measurement procedure is the same as that in Example 1. The measurement results are shown in Table 8-2.

TABLE-US-00013 TABLE 7-1 Item Chemical Composition (Remainder of Fe And Impurities) Total of Mn, Cu, Mg And C Si sol. Al S N Mn Cu Ni And Ni Co Sn Sb P The Like Left [mass [mass [mass [mass [mass [mass [mass [mass [mass [mass [mass [mass [mass [mass Side in No. %] %] %] %] %] %] %] %] %] %] %] %] %] %] Equation 401 0.0013 3.10 0.30 0.0021 0.0011 3.5 3.5 — — — 0.100 — 2.90 402 0.0013 3.10 0.30 0.0021 0.0011 3.5 3.5 — — — 0.100 — 2.90 403 0.0013 3.10 0.30 0.0021 0.0011 3.5 3.5 — — — 0.100 — 2.90 404 0.0013 3.30 0.95 0.0021 0.0011 2.5 2.5 — — — 0.100 — −0.60   405 0.0013 3.30 0.95 0.0021 0.0011 2.5 2.5 — — — 0.100 — −0.60   406 0.0013 3.10 0.30 0.0021 0.0011 3.5 3.5 — — — 0.100 — 2.90 407 0.0013 3.10 0.30 0.0021 0.0011 3.5 3.5 — — — 0.100 — 2.90 408 0.0013 3.10 0.30 0.0021 0.0011 3.5 3.5 — — — 0.100 — 2.90 409 0.0013 3.10 0.30 0.0021 0.0011 3.5 3.5 — — — 0.100 — 2.90 410 0.0013 3.10 0.30 0.0021 0.0011 3.5 3.5 — — — 0.100 — 2.90 411 0.0013 3.10 0.30 0.0021 0.0011 3.5 3.5 — — — 0.100 — 2.90

TABLE-US-00014 TABLE 7-2 Item Hot Rolling Step Finish Cooling Step Transformation Point Rolling Time to Temperature Ar3 Ar1 Ac1 Temperature Start After 3 Temperature Temperature Temperature FT Cooling Seconds No. [° C.] [° C.] [° C.] [° C.] sec [° C.] 401 830 745 913 950 0.10 700 402 830 745 913 950 0.10 700 403 830 745 913 950 0.10 700 404 — — — 950 0.10 700 405 — — — 950 0.10 700 406 830 745 913 950 0.10 250 407 830 745 913 950 0.10 250 408 830 745 913 950 0.10 700 409 830 745 913 950 0.10 700 410 830 745 913 950 0.10 700 411 830 745 913 950 0.10 700 Item Cold Intermediate Skin Pass Final After Hot Rolling annealing Rolling Annealing Rolling Step Step Step Step Average Rolling Annealing Rolling Annealing Grain Reduction Temperature Reduction Temperature Size RR1 T1 RR2 T2 No. [μm] [%] [° C.] [%] [° C.] Evaluation 401 5.0 86 700 15 760 Inventive Example 402 5.0 86 700 15 880 Inventive Example 403 5.0 86 700 15 950 Comparative Example 404 15.3 86 700 15 760 Comparative Example 405 15.3 86 700 15 880 Comparative Example 406 4.2 86 700 15 760 Comparative Example 407 4.2 86 700 15 880 Comparative Example 408 5.0 86 700 25 700 Comparative Example 409 5.0 86 700 25 880 Comparative Example 410 5.0 86 700 15 800 Inventive Example 411 5.0 86 700 15 850 Inventive Example

TABLE-US-00015 TABLE 8-1 Item Texture After Intermediate Texture After Skin Pass Texture After Final Annealing annealing {100}<011> φ1 at Φ at α-Fiber α-Fiber ODF {411}<011> {411}<011> {hkl}<011> A411-011/ A411-011/ Ratio A.sub.aα Ratio A.sub.sα Intensity Gs Ratio ODF max ODF max A411-148 A100-011 No. [%] [%] [—] [—] [%] [°] [°] [—] [—] 401 29.8 30.4 7.4 2.1 27.8 0 20 1.5 3.0 402 29.8 30.4 11.2  2.1 41.7 0 20 2.0 6.4 403 29.8 30.4 6.5 2.1 10.2 0 20 1.1 2.1 404 12.9 14.2 2.2 2.3  8.2 20 55 0.5 1.0 405 12.9 14.2 2.3 2.3  7.8 20 55 0.4 0.9 406 32.1 31.5 18.7  2.1 13.4 0 0 1.3 0.9 407 32.1 31.5 20.3  2.1 12.2 0 0 1.2 0.7 408 29.8 30.9 1.4 4.1 14.1 0 30 1.1 3.4 409 29.8 30.9 1.2 4.1 12.3 0 30 1.2 4.7 410 29.8 30.4 7.3 2.1 30.4 0 20 1.8 5.1 411 29.8 30.4 7.1 2.1 35.6 0 20 2.0 5.8

TABLE-US-00016 TABLE 8-2 Item Magnetic Characteristics Microstructure B50 Iron Loss Sheet Average (Whole B50 W10/400 Deterioration Thickness Grain Size Circumference) (45°) (45°) Ratio W.sub.x No. [mm] [μm] [T] [T] [W/kg] [%] Evaluation 401 0.30 54.2 1.58 1.70 13.4 29.9 Inventive Example 402 0.30 69.5 1.61 1.71 13.2 26.7 Inventive Example 403 0.30 33.2 1.51 1.48 16.2 34.8 Comparative Example 404 0.30 60.3 1.66 1.55 14.7 51.9 Comparative Example 405 0.30 61.2 1.63 1.54 14.8 52.7 Comparative Example 406 0.30 55.3 1.63 1.74 13.0 52.2 Comparative Example 407 0.30 80.7 1.63 1.73 13.3 53.8 Comparative Example 408 0.30 71.7 1.57 1.62 14.6 34.3 Comparative Example 409 0.30 75.8 1.59 1.63 14.3 33.7 Comparative Example 410 0.30 62.3 1.61 1.71 13.3 27.5 Inventive Example 411 0.30 68.5 1.61 1.71 13.2 26.4 Inventive Example

[0235] Underlines in Table 7-1, Table 7-2, Table 8-1, and Table 8-2 indicate conditions deviating from the scope of the present invention.

[0236] Nos. 401 and 402 of Inventive Examples had good values for all of the magnetic flux density B50 in the 450 direction, the iron loss W1&400, and the iron loss deterioration ratio.

[0237] On the other hand, No. 403 was manufactured by the same step as Nos. 401 and 402 of inventive steels until the skin pass rolling, and in a state before the final annealing, it satisfied an embodiment of the present invention (Claim 4 as a product, and Claim 9 as the manufacturing method), but was not final-annealed at a higher temperature than the Ac1 temperature. Therefore, the obtained non-oriented electrical steel sheet after the final annealing did not satisfy Claim 1 as a product having an average grain size of 50 μm or less. As a result, No. 403 had poor magnetic flux density B50 (45° direction) and the iron loss W10/400 (45° direction). Therefore, No. 403 is a Comparative Example. Nos. 404 and 405 of Comparative Examples had poor magnetic flux density B50 (450 direction), iron loss W10/400 (45° direction), and iron loss deterioration ratio because they had a composition in which α-γ transformation does not occur. Nos. 406 and 407 of Comparative Examples had large iron loss deterioration ratios under the compressive stress because of the rapid cooling after the finish rolling. Nos. 408 and 409 of Comparative Examples had poor magnetic flux density B50 (45° direction) and iron loss W10/400 (45° direction) because the rolling reduction RR2 in the skin pass rolling was very large.