NON-ORIENTED ELECTRICAL STEEL SHEET

Abstract

What is provided is a non-oriented electrical steel sheet having a chemical composition in which, by mass %, C: 0.010% or less, Si: 1.50% to 4.00%, sol. Al: 0.0001% to 1.0%, S: 0.010% or less, N: 0.010% or less, one or a plurality of elements selected from the group consisting of Mn, Ni, Co, Pt, Pb, Cu and Au: 2.50% to 5.00% in total are contained and a remainder includes Fe and impurities, in which a sheet thickness is 0.50 mm or less, and, in an arbitrary cross section, when an area ratio of {100} crystal grains is indicated by Sac, an area ratio of {110} crystal grains is indicated by Sag, and an area ratio of the {100} crystal grains in a region of up to 20% from a side where a KAM value is high is indicated by Sbc, Sac>Sbc>Sag and 0.05>Sag are satisfied.

Claims

1. A non-oriented electrical steel sheet having a chemical composition in which, by mass %: C: 0.010% or less, Si: 1.50% to 4.00%, sol. Al: 0.0001% to 1.0%, S: 0.010% or less, N: 0.010% or less, one or a plurality of elements selected from the group consisting of Mn, Ni, Co, Pt, Pb, Cu and Au: 2.50% to 5.00% in total, Sn: 0.000% to 0.400%, Sb: 0.000% to 0.400%, P: 0.000% to 0.400%, and one or a plurality of elements selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd: 0.0000% to 0.0100% in total are contained, when a Mn content (mass %) is indicated by [Mn], a Ni content (mass %) is indicated by [Ni], a Co content (mass %) is indicated by [Co], a Pt content (mass %) is indicated by [Pt], a Pb content (mass %) is indicated by [Pb], a Cu content (mass %) is indicated by [Cu], a Au content (mass %) is indicated by [Au], a Si content (mass %) is indicated by [Si], and a sol. Al content (mass %) is indicated by [sol. Al], Formula (1) below is satisfied, and a remainder includes Fe and impurities, wherein a sheet thickness is 0.50 mm or less, and, in an arbitrary cross section, when an area ratio of {100} crystal grains is indicated by Sac, an area ratio of {110} crystal grains is indicated by Sag, and an area ratio of the {100} crystal grains in a region of up to 20% from a side where a kernel average misorientation (KAM) value is high is indicated by Sbc, Sac>Sbc>Sag and 0.05>Sag are satisfied,
([Mn]+[Ni]+[Co]+[Pt]+[Pb]+[Cu]+[Au])−([Si]+[sol.Al])>0%  (1).

2. The non-oriented electrical steel sheet according to claim 1, wherein, when a value of a magnetic flux density B50 in a rolling direction is indicated by B50L, a value of a magnetic flux density B50 in a direction at an angle of 45° from the rolling direction is indicated by B50D1, a value of a magnetic flux density B50 in a direction at an angle of 90° from the rolling direction is indicated by B50C, and a value of a magnetic flux density B50 in a direction at an angle of 135° from the rolling direction is indicated by B50D2, after the non-oriented electrical steel sheet is annealed at 800° C. for two hours, Formula (2) below is satisfied,
(B50D1+B50D2)/2>(B50L+B50C)/2  (2).

3. The non-oriented electrical steel sheet according to claim 2, wherein Formula (3) below is satisfied,
(B50D1+B50D2)/2>1.1×(B50L+B50C)/2  (3).

4. The non-oriented electrical steel sheet according to claim 1, further comprising, by mass %, one or a plurality of elements selected from: Sn: 0.020% to 0.400%, Sb: 0.020% to 0.400%, and P: 0.020% to 0.400%.

5. The non-oriented electrical steel sheet according to claim 1, further comprising, by mass %, one or a plurality of elements selected from: Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd: 0.0005% to 0.0100% in total.

6. The non-oriented electrical steel sheet according to claim 2, further comprising, by mass %, one or a plurality of elements selected from: Sn: 0.020% to 0.400%, Sb: 0.020% to 0.400%, and P: 0.020% to 0.400%.

7. The non-oriented electrical steel sheet according to claim 3, further comprising, by mass %, one or a plurality of elements selected from: Sn: 0.020% to 0.400%, Sb: 0.020% to 0.400%, and P: 0.020% to 0.400%.

8. The non-oriented electrical steel sheet according to claim 2, further comprising, by mass %, one or a plurality of elements selected from: Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd: 0.0005% to 0.0100% in total.

9. The non-oriented electrical steel sheet according to claim 3, further comprising, by mass %, one or a plurality of elements selected from: Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd: 0.0005% to 0.0100% in total.

10. The non-oriented electrical steel sheet according to claim 4, further comprising, by mass %, one or a plurality of elements selected from: Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd: 0.0005% to 0.0100% in total.

11. The non-oriented electrical steel sheet according to claim 6, further comprising, by mass %, one or a plurality of elements selected from: Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd: 0.0005% to 0.0100% in total.

12. The non-oriented electrical steel sheet according to claim 7, further comprising, by mass %, one or a plurality of elements selected from: Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd: 0.0005% to 0.0100% in total.

13. A non-oriented electrical steel sheet having a chemical composition in which, by mass %: C: 0.010% or less, Si: 1.50% to 4.00%, sol. Al: 0.0001% to 1.0%, S: 0.010% or less, N: 0.010% or less, one or a plurality of elements selected from Mn, Ni, Co, Pt, Pb, Cu and Au: 2.50% to 5.00% in total, Sn: 0.000% to 0.400%, Sb: 0.000% to 0.400%, P: 0.000% to 0.400%, and one or a plurality of elements selected from Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn and Cd: 0.0000% to 0.0100% in total are contained, when a Mn content (mass %) is indicated by [Mn], a Ni content (mass %) is indicated by [Ni], a Co content (mass %) is indicated by [Co], a Pt content (mass %) is indicated by [Pt], a Pb content (mass %) is indicated by [Pb], a Cu content (mass %) is indicated by [Cu], a Au content (mass %) is indicated by [Au], a Si content (mass %) is indicated by [Si], and a sol. Al content (mass %) is indicated by [sol. Al], Formula (1) below is satisfied, and a remainder includes Fe and impurities, wherein a sheet thickness is 0.50 mm or less, and, in an arbitrary cross section, when an area ratio of {100} crystal grains is indicated by Sac, an area ratio of {110} crystal grains is indicated by Sag, and an area ratio of the {100} crystal grains in a region of up to 20% from a side where a kernel average misorientation (KAM) value is high is indicated by Sbc, Sac>Sbc>Sag and 0.05>Sag are satisfied,
([Mn]+[Ni]+[Co]+[Pt]+[Pb]+[Cu]+[Au])−([Si]+[sol.Al])>0%  (1).

Description

EXAMPLES

[0083] Next, a method for manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention will be specifically described while describing examples. The examples to be described below are simply examples of the method for manufacturing the non-oriented electrical steel sheet according to the embodiment of the present invention, and the method for manufacturing the non-oriented electrical steel sheet according to the present invention is not limited to the examples to be described below.

First Example

[0084] Molten steel was cast, thereby producing ingots having compositions shown in Table 1 below. After that, the produced ingots were hot-rolled by being heated up to 1150° C. and rolled such that the sheet thicknesses reached 2.5 mm. However, in No. 110, the ingot was hot-rolled such that the sheet thickness reached 1.6 mm. In addition, after the end of finish rolling, the hot-rolled steel sheets were cooled with water and wound. The temperature (finishing temperature) in a stage of the final pass of the finish rolling at this time was 830° C. and was higher than the Ar1 temperature except for No. 108 and No. 110. In No. 108 where γ-α transformation did not occur, the finishing temperature was set to 850° C., and, in No. 110, the finishing temperature was set to 750° C., which is lower than the Ar1 temperature, for the purpose of controlling Sag. In addition, the winding temperatures at the time of the winding were set to 500° C. Here, “left side of formula” in the table indicates the value of the left side of Formula (1) described above.

[0085] Next, the hot-rolled steel sheets were pickled to remove scales. Cold rolling was carried out such that the rolling reductions changed as shown in Table 1 depending on samples. In addition, intermediate annealing was carried out for 30 seconds by heating the cold-rolled steel sheets up to 700° C., which is lower than the Ar1 temperature, in a non-oxidizing atmosphere. However, in No. 111, the intermediate annealing was carried out at 900° C., which is the Ar1 temperature or higher, for the purpose of changing the values of Sac and Sbc. Next, a second round of cold rolling (skin pass rolling) was carried out such that the rolling reductions changed as shown in Table 1 depending on the samples. In No. 112, the skin pass rolling was not carried out. Here, for No. 116, the hot-rolled steel sheet was cold-rolled to a thickness of 0.360 mm, and, after the intermediate annealing, the second round of the cold rolling was carried out until the sheet thickness reached 0.35 mm.

[0086] Next, stress relief annealing was carried out at 800° C. for two hours after the second round of the cold rolling (skin pass rolling) in order to investigate the magnetic characteristics, and the magnetic flux densities B50 were measured. As measurement samples, 55 mm×55 mm samples were collected in two directions at angles of 0° C. and 45° C. with respect to a rolling direction. In addition, the magnetic flux densities B50 of these two types of samples were measured, the value of the magnetic flux density B50 in a direction at an angle of 45° with respect to the rolling direction was regarded as B50D1, the value of the magnetic flux density B50 in a direction at an angle of 135° with respect to the rolling direction was regarded as B50D2, the value of the magnetic flux density B50 in the rolling direction was regarded as B50L, and the value of the magnetic flux density B50 in a direction at an angle of 90° with respect to the rolling direction was regarded as B50C. In addition, the average value of B50D1, B50D2, B50L and B50C was regarded as the whole circumference average of the magnetic flux density B50. These conditions and measurement results are shown in Table 1 and Table 2.

[0087] In addition, ½ layers of the steel sheets after the skin pass rolling were exposed by polishing and measured by SEM-EBSD, and the area ratios of crystal grains in each orientation and the KAM values were calculated using OIM Analysis. In addition, Sac, Sbc and Sag were each calculated from the obtained KAM values. The calculation methods therefor are as described above in the embodiment. The observed visual fields were 2400 μm, and each numerical value is the average value of each sample.

TABLE-US-00001 TABLE 1 Rolling Composition (mass %) reduction (%) Left Skin side of Cold pass No. C Si sol-Al S N Mn Ni Co Pt Pb Cu Au formula rolling rolling Note 101 0.0009 2.50 0.0085 0.0021 0.0022 3.11 — — — — — — 0.60 85 9 Invention Example 102 0.0009 2.51 0.0083 0.0023 0.0019 — 3.10 — — — — — 0.58 85 9 Invention Example 103 0.0013 2.49 0.0068 0.0019 0.0022 — — 3.12 — — — — 0.62 85 9 Invention Example 104 0.0007 2.50 0.0125 0.0023 0.0023 — — — 3.11 — — — 0.59 85 9 Invention Example 105 0.0008 2.51 0.0091 0.0021 0.0019 — — — — 3.13 — — 0.61 85 9 Invention Example 106 0.0011 2.52 0.0126 0.0020 0.0022 — — — — — 3.12 — 0.58 85 9 Invention Example 107 0.0007 2.52 0.0110 0.0018 0.0018 — — — — — — 3.13 0.60 85 9 Invention Example 108 0.0008 3.17 0.0106 0.0018 0.0022 3.07 — — — — — — −0.11   85 9 Comparative Example 109 0.0010 2.46 0.3024 0.0016 0.0024 3.43 — — — — — — 0.67 85 9 Invention Example 110 0.0008 2.47 0.0129 0.0016 0.0022 3.06 — — — — — — 0.58 66 9 Comparative Example 111 0.0009 2.54 0.0083 0.0020 0.0020 3.10 — — — — — — 0.56 85 9 Comparative Example 112 0.0010 2.47 0.0086 0.0023 0.0017 3.10 — — — — — — 0.62 85 Not Comparative performed Example 113 0.0007 2.51 0.0117 0.0023 0.0016 3.13 — — — — — — 0.61 78 9 Invention Example 114 0.0008 2.51 0.0122 0.0016 0.0018 3.13 — — — — — — 0.61 89 9 Invention Example 115 0.0013 2.53 0.0106 0.0020 0.0023 3.13 — — — — — — 0.59 96 9 Invention Example 116 0.0011 2.51 0.0107 0.0018 0.0020 3.11 — — — — — — 0.59 85 3 Invention Example 117 0.0012 2.49 0.5987 0.0020 0.0023 3.71 — — — — — — 0.62 85 9 Invention Example 118 0.0009 2.50 0.8991 0.0018 0.0020 3.99 — — — — — — 0.59 85 9 Invention Example

TABLE-US-00002 TABLE 2 Characteristics of steel sheet B50 after annealing at 800° C. for two hours (T) Sheet Whole thickness circumference B50D1 B50D2 B50L B50C Formula Formula No. Sac Sbc Sag (mm) average B50 (T) (T) (T) (T) (2) (3) Note 101 0.242 0.091 0.007 0.35 1.681 1.810 1.808 1.558 1.548 ◯ ◯ Invention Example 102 0.244 0.091 0.006 0.35 1.677 1.813 1.812 1.556 1.527 ◯ ◯ Invention Example 103 0.239 0.093 0.012 0.35 1.683 1.812 1.810 1.556 1.553 ◯ ◯ Invention Example 104 0.237 0.091 0.013 0.35 1.676 1.807 1.810 1.557 1.531 ◯ ◯ Invention Example 105 0.241 0.089 0.009 0.35 1.677 1.813 1.812 1.556 1.528 ◯ ◯ Invention Example 106 0.239 0.088 0.007 0.35 1.683 1.808 1.813 1.556 1.555 ◯ ◯ Invention Example 107 0.241 0.090 0.010 0.35 1.678 1.812 1.811 1.555 1.534 ◯ ◯ Invention Example 108 0.106 0.084 0.037 0.35 1.609 1.546 1.558 1.686 1.646 X X Comparative Example 109 0.239 0.090 0.011 0.35 1.671 1.787 1.786 1.561 1.550 ◯ ◯ Invention Example 110 0.212 0.122 0.110 0.50 1.649 1.551 1.559 1.689 1.796 X X Comparative Example 111 0.057 0.081 0.042 0.35 1.632 1.518 1.561 1.689 1.760 X X Comparative Example 112 0.154 0.033 0.039 0.35 1.631 1.536 1.561 1.687 1.740 X X Comparative Example 113 0.238 0.086 0.009 0.50 1.680 1.807 1.810 1.551 1.553 ◯ ◯ Invention Example 114 0.243 0.093 0.010 0.25 1.681 1.814 1.809 1.552 1.548 ◯ ◯ Invention Example 115 0.237 0.091 0.014 0.10 1.707 1.840 1.813 1.552 1.622 ◯ ◯ Invention Example 116 0.221 0.065 0.022 0.35 1.680 1.760 1.759 1.577 1.625 ◯ X Invention Example 117 0.240 0.091 0.008 0.35 1.658 1.777 1.780 1.548 1.528 ◯ ◯ Invention Example 118 0.244 0.091 0.009 0.35 1.649 1.769 1.768 1.540 1.520 ◯ ◯ Invention Example

[0088] Underlined values in Table 1 and Table 2 indicate conditions deviating from the scope of the present invention. In all of No. 101 to No. 107, No. 109 and No. 113 to No. 118, which were invention examples, the magnetic flux densities B50 were favorable values both in the 45° direction and on the whole circumference average. On the other hand, in No. 108, which was a comparative example, since the Si concentration was high, the value of the left side of the formula was 0 or less, and the composition did not undergo α-γ transformation, the magnetic flux densities B50 were all low. In No. 110, which was a comparative example, since Sag exceeded 0.05, the magnetic flux density was low. In No. 111 and No. 112, which were comparative examples, since Sac>Sbc>Sag was not satisfied, the magnetic flux densities B50 were all low. In the case of No. 111, it is considered that, since the temperature in the intermediate annealing was higher than the Ac1 temperature, α-γ transformation occurred, the number of the {100} crystal grains decreased, a number of distortions remained in the {100} crystal grains, and the stress relief annealing after the skin pass rolling did not make the {100} crystal grains sufficiently grow. In No. 116, the magnetic characteristics were favorable, but the rolling reduction in the skin pass rolling was changed, and thus Formula (3) was not satisfied.

Second Example

[0089] Molten steel was cast, thereby producing ingots having compositions shown in Table 3 below. After that, the produced ingots were hot-rolled by being heated up to 1150° C. and rolled such that the sheet thicknesses reached 2.5 mm. In addition, after the end of finish rolling, the hot-rolled steel sheets were cooled with water and wound. The finishing temperature in a stage of the final pass of the finish rolling at this time was 830° C. and all temperatures were higher than the Ar1 temperature. In addition, the winding temperatures at the time of the winding were set to 500° C.

[0090] Next, the hot-rolled steel sheets were pickled to remove scales. Next, cold rolling was carried out in a rolling reduction of 85% such that the sheet thickness reached 0.385 mm. In addition, intermediate annealing was carried out for 30 seconds by heating the cold-rolled steel sheets up to 700° C., which is lower than the Ar1 temperature, in a non-oxidizing atmosphere. Next, a second round of the cold rolling (skin pass rolling) was carried out in a rolling reduction of 9% until the sheet thicknesses reached 0.35 mm. Here, for No. 215, the hot-rolled steel sheet was cold-rolled to a thickness of 0.360 mm, and, after the intermediate annealing, the second round of the cold rolling was carried out until the sheet thickness reached 0.35 mm.

[0091] Next, stress relief annealing was carried out at 800° C. for two hours after the second round of the cold rolling (skin pass rolling) in order to investigate the magnetic characteristics, and the magnetic flux densities B50 and the iron losses W10/400 were measured. The magnetic flux densities B50 were measured in the same order as in the first example. On the other hand, the iron loss W10/400 was measured as an energy loss (W/kg) on a whole circumference average that was caused in a sample when an alternating-current magnetic field of 400 Hz was applied such that the maximum magnetic flux density reached 1.0 T. These conditions and results are shown in Table 3 and Table 4.

[0092] In addition, ½ layers of the steel sheets after the skin pass rolling were exposed by polishing and measured by SEM-EBSD, and the area ratios of crystal grains in each orientation and the KAM values were calculated using OIM Analysis. In addition, Sac, Sbc and Sag were each calculated from the obtained KAM values. The calculation methods therefor are as described above in the embodiment. The observed visual fields were 2400 and each numerical value is the average value of each sample.

TABLE-US-00003 TABLE 3 Composition (mass %) No. C Si sol-Al S N Mn Sn Sb P Mg Ca Sr 201 0.0013 2.51 0.0123 0.0016 0.0021 3.10 — — — — — — 202 0.0012 2.52 0.0125 0.0022 0.0018 3.11 0.05 — — — — — 203 0.0008 2.48 0.0090 0.0017 0.0024 3.09 — 0.05 — — — — 204 0.0009 2.53 0.0100 0.0021 0.0021 3.09 — — 0.05 — — — 205 0.0007 2.54 0.0104 0.0024 0.0018 3.07 — — — 0.0049 — — 206 0.0013 2.53 0.0118 0.0020 0.0017 3.11 — — — — 0.0053 — 207 0.0006 2.54 0.0113 0.0022 0.0022 3.13 — — — — — 0.0050 208 0.0014 2.52 0.0129 0.0024 0.0017 3.06 — — — — — — 209 0.0011 2.47 0.0140 0.0019 0.0024 3.12 — — — — — — 210 0.0011 2.53 0.0061 0.0022 0.0022 3.08 — — — — — — 211 0.0008 2.52 0.0103 0.0020 0.0017 3.06 — — — — — — 212 0.0006 2.52 0.0123 0.0016 0.0018 3.09 — — — — — — 213 0.0010 2.47 0.0088 0.0020 0.0018 3.07 — — — — — — 214 0.0008 2.51 0.0104 0.0024 0.0018 3.08 — — — — — — 215 0.0011 2.49 0.0096 0.0020 0.0021 3.09 0.05 — — — — — 216 0.0009 2.49 0.6026 0.0020 0.0020 3.72 0.05 — — — — — 217 0.0008 2.49 0.9021 0.0018 0.0019 4.01 0.05 — — — — — Composition (mass %) Left side of No. Ba Ce La Nd Pr Zn Cd formula 201 — — — — — — — 0.57 202 — — — — — — — 0.58 203 — — — — — — — 0.60 204 — — — — — — — 0.54 205 — — — — — — — 0.52 206 — — — — — — — 0.57 207 — — — — — — — 0.58 208 0.0047 — — — — — — 0.53 209 — 0.0052 — — — — — 0.64 210 — — 0.0053 — — — — 0.55 211 — — — 0.0051 — — — 0.53 212 — — — — 0.0054 — — 0.56 213 — — — — — 0.0048 — 0.58 214 — — — — — — 0.0051 0.56 215 — — — — — — — 0.59 216 — — — — — — — 0.62 217 — — — — — — — 0.62

TABLE-US-00004 TABLE 4 Rolling B50 after annealing at 800° C. for two hours (T) reduction (%) Whole Skin Characteristics circumference Cold pass of steel sheet average B50 W10/400 B50D1 B50D2 B50L B50C Formula Formula No. rolling rolling Sac Sbc Sag (T) (W/kg) (T) (T) (T) (T) (2) (3) Note 201 85 9 0.239 0.092 0.011 1.679 15.32 1.812 1.798 1.561 1.544 ◯ ◯ Invention Example 202 85 9 0.237 0.089 0.010 1.701 15.34 1.821 1.822 1.549 1.613 ◯ ◯ Invention Example 203 85 9 0.239 0.086 0.011 1.702 15.28 1.818 1.826 1.567 1.596 ◯ ◯ Invention Example 204 85 9 0.240 0.087 0.007 1.703 15.31 1.824 1.835 1.568 1.587 ◯ ◯ Invention Example 205 85 9 0.241 0.088 0.008 1.682 14.93 1.809 1.808 1.539 1.571 ◯ ◯ Invention Example 206 85 9 0.238 0.090 0.013 1.678 14.90 1.813 1.802 1.541 1.556 ◯ ◯ Invention Example 207 85 9 0.243 0.087 0.011 1.682 14.93 1.808 1.824 1.536 1.561 ◯ ◯ Invention Example 208 85 9 0.237 0.092 0.010 1.681 14.87 1.808 1.799 1.568 1.549 ◯ ◯ Invention Example 209 85 9 0.238 0.090 0.008 1.680 14.90 1.812 1.827 1.560 1.521 ◯ ◯ Invention Example 210 85 9 0.244 0.088 0.011 1.678 14.87 1.809 1.827 1.549 1.525 ◯ ◯ Invention Example 211 85 9 0.239 0.087 0.012 1.681 14.89 1.809 1.812 1.542 1.560 ◯ ◯ Invention Example 212 85 9 0.240 0.087 0.014 1.677 14.93 1.810 1.824 1.561 1.514 ◯ ◯ Invention Example 213 85 9 0.243 0.089 0.013 1.677 14.86 1.809 1.817 1.545 1.539 ◯ ◯ Invention Example 214 85 9 0.242 0.093 0.011 1.677 14.93 1.814 1.808 1.548 1.537 ◯ ◯ Invention Example 215 85 3 0.223 0.061 0.031 1.690 15.31 1.768 1.753 1.636 1.601 ◯ X Invention Example 216 85 9 0.237 0.093 0.011 1.648 14.32 1.765 1.788 1.530 1.511 ◯ ◯ Invention Example 217 85 9 0.240 0.092 0.009 1.640 13.80 1.770 1.745 1.517 1.528 ◯ ◯ Invention Example

[0093] No. 201 to No. 217 were all invention examples and all had favorable magnetic characteristics. In particular, the magnetic flux densities B50 were higher in No. 202 to No. 204 than in No. 201, No. 205 to No. 217, and the iron losses W10/400 were lower in No. 205 to No. 214, No. 217 and No. 217 than in No. 201 to No. 204 and No. 215. It is considered that these results were obtained by adjusting the compositions of the non-oriented electrical steel sheets. In addition, in No. 215, the magnetic characteristics were favorable, but the rolling reduction in the skin pass rolling was changed, and thus Formula (3) was not satisfied.

Third Example

[0094] Molten steel was cast, thereby producing ingots having compositions shown in Table 5 below. After that, the produced ingots were hot-rolled by being heated up to 1150° C. and rolled such that the sheet thicknesses reached 2.5 mm. In addition, after the end of finish rolling, the hot-rolled steel sheets were cooled with water and wound. The finishing temperature in a stage of the final pass of the finish rolling at this time was 830° C. and all temperatures were higher than the Ar1 temperature. In addition, the hot-rolled steel sheets were wound at winding temperatures shown in Table 6, respectively.

[0095] Next, the hot-rolled steel sheets were pickled to remove scales and cold-rolled in a rolling reduction of 85% until the sheet thicknesses reached 0.385 mm. In addition, intermediate annealing was carried out in a non-oxidizing atmosphere for 30 seconds, and the temperatures in the intermediate annealing were controlled such that the recrystallization rates became 85%. Next, a second round of the cold rolling (skin pass rolling) was carried out in a rolling reduction of 9% until the sheet thicknesses reached 0.35 mm.

[0096] Next, stress relief annealing was carried out at 800° C. for two hours after the second round of the cold rolling (skin pass rolling) in order to investigate the magnetic characteristics, and, similar to the second example, the magnetic flux densities B50 and the iron losses W10/400 were measured. The magnetic flux density B50 in each direction was measured in the same order as in the first example. On the other hand, the iron loss W10/400 was measured as an energy loss (W/kg) on a whole circumference average that was caused in a sample when an alternating-current magnetic field of 400 Hz was applied such that the maximum magnetic flux density reached 1.0 T. These conditions and results are shown in Table 5 and Table 6.

[0097] In addition, ½ layers of the steel sheets after the skin pass rolling were exposed by polishing and measured by SEM-EBSD, and the area ratios of crystal grains in each orientation and the KAM values were calculated using OIM Analysis. In addition, Sac, Sbc and Sag were each calculated from the obtained KAM values. The calculation methods therefor are as described above in the embodiment. The observed visual fields were 2400 μm, and each numerical value is the average value of each sample.

TABLE-US-00005 TABLE 5 Composition (mass %) Left Composi- side of tion C Si sol-Al S N Mn formula A 0.0009 2.51 0.0107 0.0022 0.0020 3.10 0.57 B 0.0008 2.49 0.2995 0.0020 0.0021 3.41 0.61 C 0.0012 2.49 0.4487 0.0021 0.0019 3.54 0.60 D 0.0009 2.50 0.6014 0.0018 0.0018 3.70 0.60 E 0.0009 2.50 0.7501 0.0019 0.0021 3.87 0.62

TABLE-US-00006 TABLE 6 B50 after annealing at 800° C. for two hours (T) Winding Whole Characteristics temper- circumference Composi- of steel sheet ature average B50 W10/400 B50D1 B50D2 B50L B50C Formula Formula No. tion Sac Sbc Sag (° C.) (T) (W/kg) (T) (T) (T) (T) (2) (3) Note 301 A 0.242 0.091 0.006 500 1.673 15.33 1.796 1.794 1.560 1.546 ◯ ◯ Invention Example 302 A 0.241 0.090 0.009 600 1.677 15.27 1.783 1.785 1.561 1.579 ◯ ◯ Invention Example 303 A 0.057 0.081 0.044 700 1.649 15.84 1.719 1.718 1.575 1.580 ◯ X Comparative Example 304 A 0.241 0.089 0.007 400 1.671 15.28 1.789 1.789 1.562 1.547 ◯ ◯ Invention Example 305 A 0.242 0.089 0.008 300 1.669 15.40 1.785 1.786 1.558 1.542 ◯ ◯ Invention Example 306 A 0.058 0.081 0.041 200 1.650 15.82 1.748 1.750 1.540 1.565 ◯ ◯ Comparative Example 307 B 0.242 0.091 0.006 500 1.671 15.11 1.788 1.790 1.555 1.553 ◯ ◯ Invention Example 308 B 0.241 0.090 0.009 600 1.671 14.99 1.782 1.782 1.555 1.567 ◯ ◯ Invention Example 309 B 0.057 0.081 0.044 700 1.645 15.55 1.714 1.714 1.574 1.581 ◯ X Comparative Example 310 B 0.241 0.089 0.007 400 1.665 15.10 1.785 1.784 1.554 1.537 ◯ ◯ Invention Example 311 B 0.242 0.089 0.008 300 1.663 15.09 1.781 1.782 1.555 1.536 ◯ ◯ Invention Example 312 B 0.058 0.081 0.041 200 1.646 15.61 1.747 1.746 1.534 1.563 ◯ ◯ Comparative Example 313 C 0.242 0.091 0.006 500 1.667 14.80 1.783 1.787 1.552 1.546 ◯ ◯ Invention Example 314 C 0.241 0.090 0.009 600 1.664 14.76 1.774 1.777 1.552 1.554 ◯ ◯ Invention Example 315 C 0.057 0.081 0.044 700 1.642 15.32 1.709 1.711 1.582 1.567 ◯ X Comparative Example 316 C 0.241 0.089 0.007 400 1.659 14.78 1.779 1.780 1.551 1.524 ◯ ◯ Invention Example 317 C 0.242 0.089 0.008 300 1.658 14.87 1.776 1.777 1.551 1.526 ◯ ◯ Invention Example 318 C 0.058 0.081 0.041 200 1.640 15.32 1.741 1.738 1.530 1.553 ◯ ◯ Comparative Example 319 D 0.244 0.092 0.006 500 1.659 14.29 1.777 1.780 1.546 1.534 ◯ ◯ Invention Example 320 D 0.057 0.081 0.040 700 1.629 14.79 1.705 1.705 1.552 1.554 ◯ X Comparative Example 321 D 0.056 0.083 0.043 200 1.630 14.83 1.734 1.736 1.519 1.530 ◯ ◯ Comparative Example 322 E 0.242 0.090 0.007 500 1.655 13.84 1.774 1.775 1.540 1.532 ◯ ◯ Invention Example 323 E 0.056 0.079 0.041 700 1.627 14.65 1.702 1.702 1.555 1.549 ◯ X Comparative Example 324 E 0.057 0.082 0.042 200 1.617 14.62 1.728 1.727 1.513 1.501 ◯ ◯ Comparative Example

[0098] Underlined values in Table 6 indicate conditions deviating from the scope of the present invention. In all of No. 301, No. 302, No. 304, No. 305, No. 307, No. 308, No. 310, No. 311, No. 313, No. 314, No. 316, No. 317, No. 319 and No. 322, which were invention examples, the magnetic flux densities B50 were favorable values both in the 45° direction and on the whole circumference average. On the other hand, in No. 303, No. 306, No. 309, No. 312, No. 315, No. 318, No. 320, No. 321, No. 323 and No. 324, which were comparative examples, since the winding temperatures deviated from the optimal range, the relationship of Sac>Sbc>Sag was not satisfied, and the magnetic flux densities B50 were all low.

[0099] As is understood from the above-described examples, the non-oriented electrical steel sheet according to the present invention has excellent magnetic characteristics on a whole circumference average (all-direction average) since the chemical composition, the hot rolling conditions, the cold rolling conditions, the annealing conditions and the recrystallization rate are appropriately controlled.

INDUSTRIAL APPLICABILITY

[0100] According to the present invention, it is possible to provide a non-oriented electrical steel sheet in which excellent magnetic characteristics can be obtained on a whole circumference average (all-direction average), and thus the present invention is extremely industrially available.