Non-oriented electrical steel sheet and method for manufacturing non-oriented electrical steel sheet

Abstract

A non-oriented electrical steel sheet according to one embodiment of the invention has a chemical composition represented by C: 0.0030% or less, Si: 2.00% or less, Al: 1.00% or less, Mn: 0.10% to 2.00%, S: 0.0030% or less, one or more selected from the group consisting of Mg, Ca, Sr, Ba, Nd, Pr, La, Ce, Zn, and Cd: 0.0003% or greater and less than 0.0015% in total, a parameter Q represented by Q=[Si]+2×[Al]−[Mn]: 2.00 or less; Sn: 0.00% to 0.40%, Cu: 0.00% to 1.00%, and a remainder: Fe and impurities, and a parameter R represented by R−(I.sub.100+I.sub.310+I.sub.411+I.sub.521)/(I.sub.111+I.sub.211+I.sub.332+I.sub.221) is 0.80 or greater.

Claims

1. A non-oriented electrical steel sheet comprising, as a chemical composition, by mass %: C: 0.0030% or less; Si: 2.00% or less; Al: 1.00% or less; Mn: 0.10% to 2.00%; S: 0.0030% or less; one or more selected from the group consisting of Mg, Ca, Sr, Ba, Nd, Pr, La, Ce, Zn, and Cd: 0.0003% or greater and less than 0.0015% in total; a parameter Q, represented by Formula 1, is 2.00 or less, wherein [Si] denotes a Si content (mass %), [Al] denotes an Al content (mass %), and [Mn] denotes a Mn content (mass %); Sn: 0.00% to 0.40%; Cu: 0.00% to 1.00%; and a remainder: Fe and impurities, wherein a parameter R represented by Formula 2 where I.sub.100, I.sub.310, I.sub.411, I.sub.521, I.sub.111, I.sub.211, I.sub.332, and I.sub.221 denote a {100} crystal orientation intensity, a {310} crystal orientation intensity, a {411} crystal orientation intensity, a {521} crystal orientation intensity, a {111} crystal orientation intensity, a {211} crystal orientation intensity, a {332} crystal orientation intensity, and a {221} crystal orientation intensity in a thickness middle portion, respectively, is 0.80 or greater, wherein said thickness middle portion is defined as a depth of about ½ of a sheet thickness T of the non-oriented electrical steel sheet from a rolled surface of the non-oriented electrical steel sheet,
Q=[Si]+2×[Al]−[Mn]  (Formula 1)
R=(I.sub.100+I.sub.310+I.sub.411+I.sub.521)/(I.sub.111+I.sub.211+I.sub.332+I.sub.221)  (Formula 2).

2. The non-oriented electrical steel sheet according to claim 1, wherein in the chemical composition, either Sn: 0.02% to 0.40% or Cu: 0.10% to 1.00%, or both are satisfied.

3. A method for manufacturing the non-oriented electrical steel sheet according to claim 1, comprising: continuous casting a molten steel; hot rolling a steel ingot obtained by the continuous casting; cold rolling a steel strip obtained by the hot rolling; and final annealing a cold rolled steel sheet obtained by the cold rolling, wherein the molten steel has the chemical composition according to claim 1, the steel strip has a columnar grain ratio of 80% or greater by area fraction and an average grain size of 0.10 mm or greater, and a rolling reduction in the cold rolling is 90% or less.

4. The method for manufacturing the non-oriented electrical steel sheet according to claim 3, wherein in the continuous casting, a temperature difference between one surface and the other surface of the steel ingot during solidification is 40° C. or higher.

5. The method for manufacturing the non-oriented electrical steel sheet according to claim 3, wherein in the hot rolling, a hot rolling start temperature is 900° C. or lower, and a coiling temperature for the steel strip is 650° C. or lower.

6. The method for manufacturing the non-oriented electrical steel sheet according to claim 3, wherein in the final annealing, a sheet traveling tension is 3 MPa or less, and a cooling rate from 950° C. to 700° C. is 1° C./sec or less.

7. A method for manufacturing the non-oriented electrical steel sheet according to claim 1, comprising: solidifying a molten steel; cold rolling a steel strip obtained by the solidifying; and final annealing a cold rolled steel sheet obtained by the cold rolling, wherein the molten steel has the chemical composition according to claim 1, the steel strip has a columnar grain ratio of 80% or greater by area fraction and an average grain size of 0.10 mm or greater, and a rolling reduction in the cold rolling is 90% or less.

8. The method for manufacturing the non-oriented electrical steel sheet according to claim 7, wherein in the solidifying, the molten steel is solidified by using a moving cooling wall, and a temperature of the molten steel to be injected to the moving cooling wall is adjusted to be at least 25° C. higher than a solidification temperature of the molten steel.

9. The method for manufacturing the non-oriented electrical steel sheet according to claim 7, wherein in the solidifying, the molten steel is solidified by using a moving cooling wall, and an average cooling rate from completion of the solidification of the molten steel to coiling of the steel strip is 1,000 to 3,000° C./min.

10. The method for manufacturing the non-oriented electrical steel sheet according to claim 7, wherein a sheet traveling tension in the final annealing is 3 MPa or less, and a cooling rate from 950° C. to 700° C. is 1° C./sec or less.

11. The method for manufacturing the non-oriented electrical steel sheet according to claim 4, wherein in the hot rolling, a hot rolling start temperature is 900° C. or lower, and a coiling temperature for the steel strip is 650° C. or lower.

12. The method for manufacturing the non-oriented electrical steel sheet according to claim 4, wherein in the final annealing, a sheet traveling tension is 3 MPa or less, and a cooling rate from 950° C. to 700° C. is 1° C./sec or less.

13. The method for manufacturing the non-oriented electrical steel sheet according to claim 5, wherein in the final annealing, a sheet traveling tension is 3 MPa or less, and a cooling rate from 950° C. to 700° C. is 1° C./sec or less.

14. The method for manufacturing the non-oriented electrical steel sheet according to claim 11, wherein in the final annealing, a sheet traveling tension is 3 MPa or less, and a cooling rate from 950° C. to 700° C. is 1° C./sec or less.

15. The method for manufacturing the non-oriented electrical steel sheet according to claim 8, wherein in the solidifying, the molten steel is solidified by using a moving cooling wall, and an average cooling rate from completion of the solidification of the molten steel to coiling of the steel strip is 1,000 to 3,000° C./min.

16. The method for manufacturing the non-oriented electrical steel sheet according to claim 8, wherein a sheet traveling tension in the final annealing is 3 MPa or less, and a cooling rate from 950° C. to 700° C. is 1° C./sec or less.

17. The method for manufacturing the non-oriented electrical steel sheet according to claim 9, wherein a sheet traveling tension in the final annealing is 3 MPa or less, and a cooling rate from 950° C. to 700° C. is 1° C./sec or less.

18. The method for manufacturing the non-oriented electrical steel sheet according to claim 15, wherein a sheet traveling tension in the final annealing is 3 MPa or less, and a cooling rate from 950° C. to 700° C. is 1° C./sec or less.

19. A method for manufacturing the non-oriented electrical steel sheet according to claim 2, comprising: continuous casting a molten steel; hot rolling a steel ingot obtained by the continuous casting; cold rolling a steel strip obtained by the hot rolling; and final annealing a cold rolled steel sheet obtained by the cold rolling, wherein the molten steel has the chemical composition according to claim 2, the steel strip has a columnar grain ratio of 80% or greater by area fraction and an average grain size of 0.10 mm or greater, and a rolling reduction in the cold rolling is 90% or less.

20. A method for manufacturing the non-oriented electrical steel sheet according to claim 2, comprising: solidifying a molten steel; cold rolling a steel strip obtained by the solidifying; and final annealing a cold rolled steel sheet obtained by the cold rolling, wherein the molten steel has the chemical composition according to claim 2, the steel strip has a columnar grain ratio of 80% or greater by area fraction and an average grain size of 0.10 mm or greater, and a rolling reduction in the cold rolling is 90% or less.

Description

EXAMPLES

(1) Next, the non-oriented electrical steel sheet according to the embodiment of the invention will be described in detail with reference to examples. The following examples are merely examples of the non-oriented electrical steel sheet according to the embodiment of the invention, and the non-oriented electrical steel sheet according to the invention is not limited to the following examples.

(2) (First Test)

(3) In a first test, slabs were produced by casting a molten steel having a chemical composition shown in Table 1, and the slabs were hot rolled to obtain steel strips. In Table 1, the blank indicates that the amount of the corresponding element is less than the detection limit, and the remainder consists of Fe and impurities. In Table 1, the underline indicates that the numerical value is out of the range of the invention. Next, the steel strips were cold rolled and subjected to final annealing to produce various non-oriented electrical steel sheets having a thickness of 0.50 mm. The crystal orientation intensity in a thickness middle portion of each non-oriented electrical steel sheet was measured, and a parameter R in the thickness middle portion was calculated. Table 2 shows the results thereof. In Table 2, the underline indicates that the numerical value is out of the range of the invention.

(4) TABLE-US-00001 TABLE 1 Chemical Composition (mass %) Total Content of Coarse Steel Precipitate Param- Sym- Forming eter bol C Si Al Mn S Mg Ca Sr Ba Ce Zn Cd Sn Cu Elements Q A 0.0014 1.02 0.03 0.20 0.0022 0.0005 0.0005 0.88 B 0.0013 1.05 0.02 0.18 0.0020 0.0007 0.0007 0.91 C 0.0021 1.04 0.03 0.17 0.0019 0.0008 0.0008 0.93 D 0.0025 1.00 0.03 0.18 0.0023 0.0012 0.0012 0.88 E 0.0018 1.03 0.04 0.22 0.0024 0.0013 0.0013 0.89 F 0.0019 0.98 0.04 0.17 0.0016 0.0011 0.0011 0.89 G 0.0011 1.07 0.03 0.26 0.0035 0.0004 0.0004 0.87 H 0.0021 1.02 0.03 0.21 0.0020 0.0001 0.0001 0.87 I 0.0022 1.01 0.03 0.19 0.0018 0.0021 0.0021 0.88 J 0.0020 2.46 0.02 0.22 0.0027 0.0007 0.0007 2.28 K 0.0018 1.05 0.03 0.24 0.0022 0.0009 0.0009 0.87 L 0.0016 1.09 0.03 0.21 0.0019 0.0008 0.0008 0.94 M 0.0016 0.98 0.04 0.22 0.0021 0.0009 0.0009 0.84 N 0.0020 1.00 0.03 0.22 0.0018 0.0004 0.0004 0.84 O 0.0019 1.02 0.02 0.21 0.0017 0.0006 0.0006 0.85 P 0.0017 1.02 0.02 0.24 0.0024 0.0008 0.0008 0.82 Q 0.0021 1.01 0.04 0.21 0.0022 0.0009 0.0009 0.88 R 0.0024 1.07 0.02 0.22 0.0015 0.0010 0.14 0.0010 0.89 S 0.0022 1.05 0.02 0.24 0.0018 0.0013 0.32 0.0013 0.85 K′ 0.0018 1.05 0.03 0.24 0.0015 0.0009 0.0009 0.87 L′ 0.0016 1.09 0.03 0.21 0.0010 0.0008 0.0008 0.94 M′ 0.0016 0.98 0.04 0.22 0.0005 0.0009 0.0009 0.84 N′ 0.0020 1.00 0.03 0.22 0.0005 0.0010 0.0010 0.84 O′ 0.0019 1.02 0.02 0.21 0.0005 0.0010 0.0010 0.85 P′ 0.0017 1.02 0.02 0.24 0.0005 0.0008 0.0008 0.82 Q′ 0.0021 1.01 0.04 0.21 0.0005 0.0009 0.0009 0.88 R′ 0.0024 1.07 0.02 0.22 0.0005 0.0010 0.14 0.0010 0.89 S′ 0.0022 1.05 0.02 0.24 0.0006 0.0013 0.32 0.0013 0.85 T 0.0018 1.03 0.003 0.21 0.0007 0.0005 0.0005 0.0010 0.83 TT 0.0029 1.98 0.03 1.98 0.0005 0.0010 0.0010 0.06 TTT 0.0010 0.34 0.98 1.42 0.0006 0.0010 0.0010 0.88

(5) TABLE-US-00002 TABLE 2 Crystal Orientation Intensity I Sample Steel Parameter No. Symbol I.sub.100 I.sub.310 I.sub.411 I.sub.521 I.sub.111 I.sub.211 I.sub.332 I.sub.221 R Remarks 1 A 1.03 0.88 0.68 0.43 2.01 2.33 0.48 1.29 0.49 Comparative Example 2 B 1.12 1.05 0.79 0.61 1.63 1.94 0.39 1.14 0.70 Comparative Example 3 C 0.85 0.77 0.47 0.31 2.25 1.56 0.64 1.78 0.39 Comparative Example 4 D 1.06 0.82 0.62 0.57 2.01 1.32 0.53 1.44 0.58 Comparative Example 5 E 1.11 1.23 1.08 0.52 2.21 1.65 0.99 1.22 0.65 Comparative Example 6 F 0.98 0.89 1.05 0.29 1.99 1.78 0.67 1.02 0.59 Comparative Example 7 G 1.14 1.01 0.39 0.44 1.78 1.42 0.95 1.07 0.57 Comparative Example 8 H 1.27 0.92 0.66 0.92 1.38 1.58 0.82 1.31 0.74 Comparative Example 9 I 1.19 0.88 0.45 0.70 1.58 1.49 0.54 1.14 0.68 Comparative Example 10 J 1.17 1.04 0.69 0.66 1.49 1.35 0.68 1.33 0.73 Comparative Example 11 K 1.59 0.92 0.83 0.78 0.97 1.29 0.48 0.99 1.10 Inventive Example 12 L 1.62 1.06 1.01 0.66 0.88 1.36 0.37 1.22 1.14 Inventive Example 13 M 1.44 1.22 0.89 0.71 1.02 1.16 0.29 1.08 1.20 Inventive Example 14 N 1.92 0.69 0.95 0.83 1.35 1.62 0.44 1.29 0.93 Inventive Example 15 O 1.55 0.88 1.21 0.87 0.87 1.00 0.31 1.45 1.24 Inventive Example 16 P 2.04 0.77 1.33 0.53 1.38 1.77 0.69 1.85 0.82 Inventive Example 17 Q 1.88 1.31 1.04 0.75 1.09 0.98 0.27 1.23 1.39 Inventive Example 18 R 2.63 1.05 1.93 0.43 0.66 0.68 0.66 1.15 1.92 Inventive Example 19 S 2.47 0.99 1.68 0.55 0.78 0.82 0.62 1.12 1.70 Inventive Example 11 K′ 1.60 0.91 0.82 0.79 0.98 1.28 0.49 0.98 1.10 Inventive Example 12′ L′ 1.63 1.05 1.00 0.67 0.89 1.35 0.38 1.21 1.14 Inventive Example 13′ M′ 1.45 1.21 0.88 0.72 1.03 1.15 0.30 1.07 1.20 Inventive Example 14′ N′ 1.93 0.68 0.94 0.84 1.36 1.61 0.45 1.28 0.93 Inventive Example 15′ O′ 1.56 0.87 1.20 0.88 0.88 0.99 0.32 1.44 1.24 Inventive Example 16′ P′ 2.05 0.76 1.32 0.54 1.39 1.76 0.70 1.84 0.82 Inventive Example 17′ Q′ 1.89 1.30 1.03 0.76 1.10 0.97 0.28 1.22 1.39 Inventive Example 18′ R′ 2.64 1.04 1.92 0.44 0.67 0.67 0.67 1.14 1.92 Inventive Example 19′ S′ 2.48 0.98 1.67 0.56 0.79 0.81 0.63 1.11 1.70 Inventive Example 20 T 1.61 0.90 0.81 0.80 0.99 1.27 0.50 0.97 1.10 Inventive Example 21 TT 1.64 1.04 0.99 0.68 0.90 1.34 0.39 1.20 1.52 Inventive Example 22 TTT 1.46 1.20 0.87 0.73 1.04 1.14 0.31 1.06 0.93 Inventive Example

(6) The magnetic characteristics of each non-oriented electrical steel sheet were measured. Table 3 shows the results thereof. In Table 3, the underline indicates that the numerical value is not within a desired range. That is, the underline in the column of magnetic flux density B50.sub.L indicates that the magnetic flux density is less than 1.79 T, the underline in the column of average value B50.sub.L+C indicates that the average value is less than 1.75 T, the underline in the column of iron loss W15/50.sub.L indicates the iron loss is greater than 4.5 W/kg, and the underline in the column of average value W15/50.sub.L+C indicates that the average value is greater than 5.0 W/kg.

(7) TABLE-US-00003 TABLE 3 Sample W15/50.sub.L W15/50.sub.L+C B50.sub.L B50.sub.L+C No. (W/kg) (W/kg) (T) (T) Remarks  1 5.3 5.7 1.73 1.71 Comparative Example  2 4.9 5.3 1.76 1.73 Comparative Example  3 5.4 5.7 1.73 1.70 Comparative Example  4 5.3 5.6 1.74 1.72 Comparative Example  5 5.1 5.4 1.75 1.71 Comparative Example  6 5.2 5.5 1.74 1.70 Comparative Example  7 5.2 5.6 1.74 1.71 Comparative Example  8 5.2 5.5 1.77 1.73 Comparative Example  9 5.0 5.3 1.75 1.72 Comparative Example 10 3.5 3.8 1.73 1.69 Comparative Example 11 4.2 4.5 1.81 1.78 Inventive Example 12 4.2 4.4 1.81 1.78 Inventive Example 13 4.1 4.4 1.82 1.79 Inventive Example 14 4.4 4.7 1.79 1.77 Inventive Example 15 4.1 4.3 1.82 1.80 Inventive Example 16 4.4 4.8 1.79 1.76 Inventive Example 17 4.1 4.3 1.81 1.79 Inventive Example 18 3.8 4.1 1.83 1.81 Inventive Example 19 4.0 4.2 1.83 1.80 Inventive Example 11′ 4.1 4.4 1.80 1.77 Inventive Example 12′ 4.1 4.3 1.80 1.77 Inventive Example 13′ 4.0 4.3 1.81 1.78 Inventive Example 14′ 4.3 4.6 1.79 1.76 Inventive Example 15′ 4.0 4.2 1.81 1.79 Inventive Example 16′ 4.3 4.7 1.79 1.75 Inventive Example 17′ 4.0 4.2 1.80 1.78 Inventive Example 18′ 3.7 4.0 1.82 1.80 Inventive Example 19′ 3.9 4.1 1.82 1.79 Inventive Example 20 4.0 4.3 1.79 1.76 Inventive Example 21 4.0 4.2 1.79 1.76 Inventive Example 22 3.9 4.2 1.80 1.77 Inventive Example

(8) As shown in Table 3, in Sample Nos. 11 to 22 and 11′ to 19′, the chemical composition was within the range of the invention, and the parameter R in the thickness middle portion was within the range of the invention. Accordingly, good magnetic characteristics were obtained.

(9) In Sample Nos. 1 to 6, since the parameter R in the thickness middle portion was excessively low, the iron loss W15/50.sub.L and the average value W15/50.sub.L+C were high, and the magnetic flux density B50.sub.L and the average value B50.sub.L+C were low. In Sample No. 7, since the S content was excessively high, the iron loss W15/50.sub.L and the average value W15/50.sub.L+C were high, and the magnetic flux density B50.sub.L and the average value B50.sub.L+C were low. In Sample No. 8, since the total amount of the coarse precipitate forming elements was excessively low, the ratio of the total mass of S contained in the sulfides or oxysulfides of the coarse precipitate forming elements to the total mass of S contained in the non-oriented electrical steel sheet was less than 40%, the iron loss W15/50.sub.L and the average value W15/50.sub.L+C were high, and the magnetic flux density B50.sub.L and the average value B50.sub.L+C were low. In Sample No. 9, since the total amount of the coarse precipitate forming elements was excessively high, the ratio of the total mass of S contained in the sulfides or oxysulfides of the coarse precipitate forming elements to the total mass of S contained in the non-oriented electrical steel sheet was 40% or greater. However, Ca formed many inclusions such as CaO, the iron loss W15/50.sub.L and the average value W15/50.sub.L+C were high, and the magnetic flux density B50.sub.L and the average value B50.sub.L+C were low. In Sample No. 10, since the parameter Q was excessively high, the magnetic flux density B50.sub.L and the average value B50.sub.L+C were low.

(10) (Second Test)

(11) In a second test, molten steels (corresponding to Sample Nos. 31 to 33 in Table 4-1) containing, by mass %, C: 0.0023%, Si: 0.81%, Al: 0.03%, Mn: 0.20%, S: 0.0003%, and Pr: 0.0007% with a remainder consisting of Fe and impurities, and molten steels (corresponding to Sample Nos. 31′ to 33′ in Table 4-1) containing C: 0.0021%, Si: 0.83%, Al: 0.05%, Mn: 0.19%, S: 0.0007%, and Pr: 0.0013% with a remainder consisting of Fe and impurities were cast to produce slabs, and the slabs were hot rolled to obtain steel strips having a thickness of 2.1 mm. During casting, the temperature difference between two surfaces of the cast piece was adjusted to change the columnar grain ratio and the average grain size of the steel strip. Table 4-2 shows the temperature difference between the two surfaces, the columnar grain ratio, and the average grain size. Next, cold rolling was performed at a rolling reduction of 78.2% to obtain a steel sheet having a thickness of 0.50 mm. Thereafter, continuous final annealing was performed for 30 seconds at 850° C. to obtain a non-oriented electrical steel sheet. Then, intensities of eight crystal orientations of each non-oriented electrical steel sheet were measured, and a parameter R in a thickness middle portion was calculated. Table 4-2 also shows the results thereof. In Table 4-2, the underline indicates that the numerical value is out of the range of the invention.

(12) TABLE-US-00004 TABLE 4-1 Chemical Composition (mass %) Total Content of Coarse Pre- Pa- Sam- cipitate ram- ple Forming eter No. C Si Al Mn S Pr Elements Q 31 0.0023 0.81 0.03 0.20 0.0003 0.0007 0.0007 0.67 32 0.0023 0.81 0.03 0.20 0.0003 0.0007 0.0007 0.67 33 0.0023 0.81 0.03 0.20 0.0003 0.0007 0.0007 0.67 31′ 0.0021 0.83 0.05 0.19 0.0007 0.0013 0.0013 0.74 32′ 0.0021 0.83 0.05 0.19 0.0007 0.0013 0.0013 0.74 33′ 0.0021 0.83 0.05 0.19 0.0007 0.0013 0.0013 0.74

(13) TABLE-US-00005 TABLE 4-2 Average Grain Temperature Columnar Size of Sample Difference Grain Ratio Steel Strip Crystal Orientation Intensity I Parameter No. (° C.) (area %) (mm) I.sub.100 I.sub.310 I.sub.411 I.sub.521 I.sub.111 I.sub.211 I.sub.332 I.sub.221 R Remarks 31 14 45 0.18 0.76 0.55 0.49 0.92 1.48 2.02 0.51 1.15 0.53 Comparative Example 32 35 71 0.21 1.11 0.73 0.47 0.89 1.33 1.51 0.48 1.01 0.74 Comparative Example 33 67 86 0.19 1.77 1.29 0.88 0.78 1.19 1.45 0.25 1.18 1.16 Inventive Example 31′ 17 48 0.15 0.75 0.56 0.48 0.93 1.49 2.01 0.52 1.14 0.53 Comparative Example 32′ 36 73 0.19 1.10 0.74 0.46 0.90 1.34 1.50 0.49 1.00 0.74 Comparative Example 33′ 65 85 0.22 1.76 1.30 0.87 0.79 1.20 1.44 0.26 1.17 1.16 Inventive Example

(14) The magnetic characteristics of each non-oriented electrical steel sheet were measured. Table 5 shows the results thereof. In Table 5, the underline indicates that the numerical value is not within a desired range. That is, the underline in the column of magnetic flux density B50.sub.L indicates that the magnetic flux density is less than 1.79 T, the underline in the column of average value B50.sub.L+C indicates that the average value is less than 1.75 T, the underline in the column of iron loss W15/50.sub.L indicates the iron loss is greater than 4.5 W/kg, and the underline in the column of average value W15/50.sub.L+C indicates that the average value is greater than 5.0 W/kg.

(15) TABLE-US-00006 TABLE 5 Sample W15/50.sub.L W15/50.sub.L+C B50.sub.L B50.sub.L+C No. (W/kg) (W/kg) (T) (T) Remarks 31 5.3 5.7 1.75 1.72 Comparative Example 32 5.0 5.5 1.77 1.73 Comparative Example 33 4.4 4.6 1.82 1.80 Inventive Example 31′ 5.4 5.8 1.74 1.71 Comparative Example 32′ 5.1 5.6 1.76 1.72 Comparative Example 33′ 4.5 4.7 1.81 1.79 Inventive Example

(16) As shown in Table 5, in Sample Nos. 33 and 33′ using a steel strip having an appropriate columnar grain ratio, since the parameter R in the thickness middle portion was within the range of the invention, good magnetic characteristics were obtained.

(17) In Sample Nos. 31, 32, 31′, and 32′ using a steel strip having an excessively low columnar grain ratio, since the parameter R in the thickness middle portion was out of the range of the invention, the iron loss W15/50.sub.L and the average value W15/50.sub.L+C were high, and the magnetic flux density B50.sub.L and the average value B50.sub.L+C were low.

(18) (Third Test)

(19) In a third test, molten steels each having a chemical composition shown in Table 6 were cast to produce slabs, and the slabs were hot rolled to obtain steel strips having a thickness of 2.4 mm. The remainder consists of Fe and impurities, and in Table 6, the underline indicates that the numerical value is out of the range of the invention. During casting, the temperature difference between two surfaces of the cast piece and the average cooling rate at 700° C. or higher were adjusted to change the columnar grain ratio and the average grain size of the steel strip. The temperature difference between the two surfaces was 48° C. to 60° C. In Sample Nos. 41, 42, 41′, and 42′, the average cooling rate at 700° C. or higher was 20° C./min, and in other samples, the average cooling rate at 700° C. or higher was 10° C./min or less. Table 7 shows the columnar grain ratio and the average grain size. Next, cold rolling was performed at a rolling reduction of 79.2% to obtain a steel sheet having a thickness of 0.50 mm. Thereafter, continuous final annealing was performed for 45 seconds at 880° C. to obtain a non-oriented electrical steel sheet. Then, intensities of eight crystal orientations of each non-oriented electrical steel sheet were measured, and a parameter R in a thickness middle portion was calculated. Table 7 also shows the results thereof. In Table 7, the underline indicates that the numerical value is out of the range of the invention.

(20) TABLE-US-00007 TABLE 6 Total Content of Coarse Pre- Pa- Steel cipitate ram- Sym- Chemical Composition (mass %) Forming eter bol C Si Al Mn S Cd Elements Q U 0.0025 1.21 0.22 0.33 0.0011 0.0011 0.0011 1.32 V 0.0024 1.24 0.20 0.36 0.0012 0.0010 0.0010 1.28 W 0.0022 1.22 0.18 0.32 0.0009 0.0002 0.0002 1.26 X 0.0027 1.29 0.18 0.37 0.0010 0.0012 0.0012 1.28 Y 0.0021 1.22 0.20 0.31 0.0008 0.0023 0.0023 1.31 U′ 0.0025 1.21 0.22 0.33 0.0005 0.0011 0.0011 1.32 V′ 0.0024 1.24 0.20 0.36 0.0006 0.0010 0.0010 1.28 W′ 0.0022 1.22 0.18 0.32 0.0007 0.0002 0.0002 1.26 X′ 0.0027 1.29 0.18 0.37 0.0005 0.0012 0.0012 1.28 Y′ 0.0021 1.22 0.20 0.31 0.0007 0.0023 0.0023 1.31

(21) TABLE-US-00008 TABLE 7 Average Grain Size Columnar of Steel Sample Steel Grain Ratio Strip Crystal Orientation Intensity I Parameter No. Symbol (area %) (mm) I.sub.100 I.sub.310 I.sub.411 I.sub.521 I.sub.111 I.sub.211 I.sub.332 I.sub.221 R Remarks 41 U 88 0.05 1.23 0.58 1.02 1.32 2.41 2.37 1.02 1.76 0.55 Comparative Example 42 V 87 0.07 1.48 0.74 0.62 0.93 1.97 2.14 0.89 1.19 0.61 Comparative Example 43 W 92 0.16 1.65 0.81 0.73 0.89 2.51 1.84 0.79 1.06 0.66 Comparative Example 44 X 90 0.15 2.11 1.19 1.23 1.04 0.88 1.15 0.67 0.96 1.52 Inventive Example 45 Y 91 0.18 1.48 0.77 0.64 1.01 2.87 2.35 0.75 1.14 0.55 Comparative Example 41′ U′ 90 0.07 1.22 0.59 1.01 1.33 2.42 2.36 1.03 1.75 0.55 Comparative Example 42′ V′ 88 0.06 1.47 0.75 0.61 0.94 1.98 2.13 0.90 1.18 0.61 Comparative Example 43′ W′ 91 0.15 1.64 0.82 0.72 0.90 2.52 1.83 0.80 1.05 0.66 Comparative Example 44′ X′ 88 0.16 2.10 1.20 1.22 1.05 0.89 1.14 0.68 0.95 1.52 Inventive Example 45′ Y′ 90 0.17 1.47 0.78 0.63 1.02 2.88 2.34 0.76 1.13 0.55 Comparative Example

(22) The magnetic characteristics of each non-oriented electrical steel sheet were measured. Table 8 shows the results thereof. In Table 8, the underline indicates that the numerical value is not within a desired range. That is, the underline in the column of magnetic flux density B50.sub.L indicates that the magnetic flux density is less than 1.79 T, the underline in the column of average value B50.sub.L+C indicates that the average value is less than 1.75 T, the underline in the column of iron loss W15/50.sub.L indicates the iron loss is greater than 4.5 W/kg, and the underline in the column of average value W15/50.sub.L+C indicates that the average value is greater than 5.0 W/kg.

(23) TABLE-US-00009 TABLE 8 Sample W15/50.sub.L W15/50.sub.L+C B50.sub.L B50.sub.L+C No. (W/kg) (W/kg) (T) (T) Remarks 41 5.4 5.8 1.74 1.71 Comparative Example 42 5.1 5.5 1.75 1.73 Comparative Example 43 4.8 5.3 1.77 1.74 Comparative Example 44 3.9 4.2 1.81 1.79 Inventive Example 45 5.0 5.4 1.76 1.73 Comparative Example 41′ 5.3 5.7 1.73 1.70 Comparative Example 42′ 5.0 5.4 1.74 1.72 Comparative Example 43′ 4.7 5.2 1.76 1.73 Comparative Example 44′ 3.8 4.1 1.80 1.78 Inventive Example 45′ 4.9 5.3 1.75 1.72 Comparative Example

(24) As shown in Table 8, in Sample Nos. 44 and 44′ using a steel strip whose chemical composition, columnar grain ratio, and average grain size were appropriate, since the parameter R in the thickness middle portion was within the range of the invention, good magnetic characteristics were obtained.

(25) In Sample Nos. 41, 42, 41′, and 42′ using a steel strip having an excessively small average grain size, the iron loss W15/50.sub.L and the average value W15/50.sub.L+C were high, and the magnetic flux density B50.sub.L and the average value B50.sub.L+C were low. In Sample Nos. 43 and 43′, since the total amount of the coarse precipitate forming elements was excessively low, the iron loss W15/50.sub.L and the average value W15/50.sub.L+C were high, and the magnetic flux density B50.sub.L and the average value B50.sub.L+C were low. In Sample Nos. 45 and 45′, since the total amount of the coarse precipitate forming elements was excessively high, the iron loss W15/50.sub.L and the average value W15/50.sub.L+C were high, and the magnetic flux density B50.sub.L and the average value B50.sub.L+C were low.

(26) (Fourth Test)

(27) In a fourth test, molten steels each having a chemical composition shown in Table 9 were cast to produce slabs, and the slabs were hot rolled to obtain steel strips having a thickness shown in Table 10. In Table 9, the blank indicates that the amount of the corresponding element is less than the detection limit, and the remainder consists of Fe and impurities. During casting, the temperature difference between two surfaces of the cast piece was adjusted to change the columnar grain ratio and the average grain size of the steel strip. The temperature difference between the two surfaces was 51° C. to 68° C. Table 10 also shows the columnar grain ratio and the average grain size. Next, cold rolling was performed at a rolling reduction shown in Table 10 to obtain a steel sheet having a thickness of 0.50 mm. After that, continuous final annealing was performed for 40 seconds at 830° C. to obtain a non-oriented electrical steel sheet. Then, intensities of eight crystal orientations of each non-oriented electrical steel sheet were measured, and a parameter R in a thickness middle portion was calculated. Table 10 also shows the results thereof. In Table 10, the underline indicates that the numerical value is out of the range of the invention.

(28) TABLE-US-00010 TABLE 9 Chemical Composition (mass %) Total Content of Steel Coarse Precipitate Parameter Symbol C Si Al Mn S Ba Sn Cu Forming Elements Q Z 0.0017 0.53 0.32 0.49 0.0022 0.0007 0.0007 0.68 AA 0.0018 0.54 0.29 0.51 0.0019 0.0008 0.0008 0.61 BB 0.0014 0.51 0.28 0.50 0.0018 0.0008 0.09 0.0008 0.57 CC 0.0016 0.51 0.33 0.47 0.0022 0.0006 0.48 0.0006 0.70 DD 0.0012 0.52 0.25 0.45 0.0020 0.0007 0.21 0.32 0.0007 0.57 EE 0.0013 0.56 0.30 0.56 0.0021 0.0009 0.0009 0.60 Z′ 0.0017 0.53 0.32 0.49 0.0008 0.0014 0.0014 0.68 AA′ 0.0018 0.54 0.29 0.51 0.0007 0.0013 0.0013 0.61 BB′ 0.0014 0.51 0.28 0.50 0.0005 0.0013 0.09 0.0013 0.57 CC′ 0.0016 0.51 0.33 0.47 0.0007 0.0012 0.48 0.0012 0.70 DD′ 0.0012 0.52 0.25 0.45 0.0006 0.0014 0.21 0.32 0.0014 0.57 EE′ 0.0013 0.56 0.30 0.56 0.0008 0.0014 0.0014 0.60

(29) TABLE-US-00011 TABLE 10 Average Thickness Columnar Grain Size of Steel Grain of Steel Rolling Sample Steel Strip Ratio Strip Reduction Crystal Orientation Intensity I Parameter No. Symbol (mm) (area %) (mm) (%) I.sub.100 I.sub.310 I.sub.411 I.sub.521 I.sub.111 I.sub.211 I.sub.332 I.sub.221 R Remarks 51 Z 0.95 92 0.22 47.4 1.33 1.02 0.97 0.65 1.01 1.17 0.29 1.13 1.10 Inventive Example 52 AA 1.55 97 0.21 67.7 1.54 1.20 1.38 0.77 0.95 1.06 0.46 0.89 1.46 Inventive Example 53 BB 2.03 88 0.24 75.4 1.66 1.19 1.51 0.83 0.77 1.01 0.52 0.78 1.69 Inventive Example 54 CC 2.55 90 0.23 80.4 1.59 1.24 1.36 0.94 0.83 1.15 0.42 1.05 1.49 Inventive Example 55 DD 3.76 100 0.20 86.7 1.83 1.15 1.64 0.78 0.69 0.88 0.39 0.92 1.88 Inventive Example 56 EE 5.62 86 0.21 91.1 1.44 0.87 1.23 0.69 1.84 2.05 0.76 1.18 0.73 Comparative Example 51′ Z′ 0.94 95 0.21 46.8 1.34 1.01 0.98 0.64 1.02 1.16 0.30 1.12 1.10 Inventive Example 52′ AA′ 1.56 98 0.23 67.9 1.55 1.19 1.39 0.76 0.96 1.05 0.47 0.88 1.46 Inventive Example 53′ BB′ 2.01 91 0.22 75.1 1.67 1.18 1.52 0.82 0.78 1.00 0.53 0.77 1.69 Inventive Example 54′ CC′ 2.53 93 0.21 80.2 1.60 1.23 1.37 0.93 0.84 1.14 0.43 1.04 1.49 Inventive Example 55′ DD′ 3.74 98 0.21 86.6 1.84 1.14 1.65 0.77 0.70 0.87 0.40 0.91 1.88 Inventive Example 56′ EE′ 5.60 88 0.22 91.1 1.45 0.86 1.24 0.68 1.85 2.01 0.77 1.17 0.73 Comparative Example

(30) The magnetic characteristics of each non-oriented electrical steel sheet were measured. Table 11 shows the results thereof. In Table 11, the underline indicates that the numerical value is not within a desired range. That is, the underline in the column of magnetic flux density B50.sub.L indicates that the magnetic flux density is less than 1.79 T, the underline in the column of average value B50.sub.L+C indicates that the average value is less than 1.75 T, the underline in the column of iron loss W15/50.sub.L indicates the iron loss is greater than 4.5 W/kg, and the underline in the column of average value W15/50.sub.L+C indicates that the average value is greater than 5.0 W/kg.

(31) TABLE-US-00012 TABLE 11 Sample W15/50.sub.L W15/50.sub.L+C B50.sub.L B50.sub.L+C No. (W/kg) (W/kg) (T) (T) Remarks 51 4.4 4.6 1.79 1.76 Inventive Example 52 4.2 4.4 1.80 1.77 Inventive Example 53 3.9 4.2 1.83 1.81 Inventive Example 54 4.0 4.3 1.82 1.79 Inventive Example 55 3.8 4.0 1.84 1.82 Inventive Example 56 4.8 5.2 1.77 1.73 Comparative Example 51′ 4.3 4.5 1.79 1.75 Inventive Example 52′ 4.1 4.3 1.79 1.76 Inventive Example 53′ 3.8 4.1 1.82 1.80 Inventive Example 54′ 3.9 4.2 1.81 1.78 Inventive Example 55′ 3.7 3.9 1.83 1.81 Inventive Example 56′ 4.7 5.1 1.76 1.72 Comparative Example

(32) As shown in Table 11, in Sample Nos. 51 to 55 and 51′ to 55′ using a steel strip whose chemical composition, columnar grain ratio, and average grain size were appropriate, and cold rolled at an appropriate reduction, since the parameter R in the thickness middle portion was within the range of the invention, good magnetic characteristics were obtained. In Sample Nos. 53, 54, 53′, and 54′ containing an appropriate amount of Sn or Cu, particularly excellent results were obtained in the iron loss W15/50.sub.L, average value W15/50.sub.L+C magnetic flux density B50.sub.L, and average value B50.sub.L+C. In Sample Nos. 55 and 55′ containing an appropriate amount of Sn and Cu, more excellent results were obtained in the iron loss W15/50.sub.L, average value W15/50.sub.L+C, magnetic flux density B50.sub.L, and average value B50.sub.L+C.

(33) In Sample Nos. 56 and 56′ in which the rolling reduction of cold rolling was excessively high, the iron loss W15/50.sub.L and the average value W15/50.sub.L+C were high, and the magnetic flux density B50.sub.L and the average value B50.sub.L+C were low.

(34) (Fifth Test)

(35) In a fifth test, molten steels (corresponding to Sample Nos. 61 to 64 in Table 12-1) containing, by mass %, C: 0.0014%, Si: 0.34%, Al: 0.48%, Mn: 1.42%, S: 0.0017%, and Sr: 0.0011% with a remainder consisting of Fe and impurities, and molten steels (corresponding to Sample Nos. 61′ to 64′ in Table 12-1) containing C: 0.0015%, Si: 0.35%, Al: 0.47%, Mn: 1.41%, S: 0.0007%, and Sr: 0.0014% with a remainder consisting of Fe and impurities were cast to produce slabs, and the slabs were hot rolled to obtain steel strips having a thickness of 2.3 mm. During casting, the temperature difference between two surfaces of the cast piece was adjusted to 59° C. such that the columnar grain ratio of the steel strip was 90% and the average grain size was 0.17 mm. Next, cold rolling was performed at a rolling reduction of 78.3% to obtain a steel sheet having a thickness of 0.50 mm. Thereafter, continuous final annealing was performed for 20 seconds at 920° C. to obtain a non-oriented electrical steel sheet. In final annealing, the sheet traveling tension and the cooling rate from 950° C. to 700° C. were changed. Table 12-2 shows the sheet traveling tension and the cooling rate. The crystal orientation intensity of each non-oriented electrical steel sheet was measured, and a parameter R in a thickness middle portion was calculated. Table 12-2 also shows the results thereof.

(36) TABLE-US-00013 TABLE 12-1 Chemical Composition (mass %) Total Content of Sample Coarse Precipitate Parameter No. C Si Al Mn S Sr Forming Elements Q 61 0.0014 0.34 0.48 1.42 0.0017 0.0011 0.0011 −0.12 62 0.0014 0.34 0.48 1.42 0.0017 0.0011 0.0011 −0.12 63 0.0014 0.34 0.48 1.42 0.0017 0.0011 0.0011 −0.12 64 0.0014 0.34 0.48 1.42 0.0017 0.0011 0.0011 −0.12 61′ 0.0015 0.35 0.47 1.41 0.0007 0.0013 0.0013 −0.12 62′ 0.0015 0.35 0.47 1.41 0.0007 0.0013 0.0013 −0.12 63′ 0.0015 0.35 0.47 1.41 0.0007 0.0013 0.0013 −0.12 64′ 0.0015 0.35 0.47 1.41 0.0007 0.0013 0.0013 −0.12

(37) TABLE-US-00014 TABLE 12-2 Sheet Elastic Traveling Cooling Strain Sample Tension Rate Anisotropy Crystal Orientation Intensity I Parameter No. (MPa) (° C./sec) (%) I.sub.100 I.sub.310 I.sub.411 I.sub.521 I.sub.111 I.sub.211 I.sub.332 I.sub.221 R Remarks 61 4.5 2.3 1.18 1.39 0.96 1.35 1.00 1.55 0.64 1.18 1.69 0.93 Inventive Example 62 2.6 2.6 1.09 1.56 1.04 1.55 1.21 1.38 0.71 1.17 1.38 1.16 Inventive Example 63 1.8 2.4 1.07 1.87 1.11 1.61 1.13 1.30 0.59 1.21 1.41 1.27 Inventive Example 64 1.6 0.7 1.03 2.38 1.18 2.16 1.22 1.21 0.66 1.09 1.36 1.61 Inventive Example 61′ 4.3 2.4 1.17 1.38 0.97 1.34 1.01 1.54 0.65 1.17 1.70 0.93 Inventive Example 62′ 2.5 2.5 1.10 1.55 1.05 1.54 1.22 1.37 0.72 1.16 1.39 1.16 Inventive Example 63′ 1.5 2.3 1.06 1.86 1.12 1.60 1.14 1.29 0.60 1.20 1.42 1.27 Inventive Example 64′ 1.7 0.6 1.04 2.37 1.19 2.15 1.23 1.20 0.67 1.08 1.37 1.61 Inventive Example

(38) The magnetic characteristics of each non-oriented electrical steel sheet were measured. Table 13 shows the results thereof.

(39) TABLE-US-00015 TABLE 13 Sample W15/50.sub.L W15/50.sub.L+C B50.sub.L B50.sub.L+C No. (W/kg) (W/kg) (T) (T) Remarks 61 4.2 4.4 1.82 1.80 Inventive Example 62 3.9 4.1 1.83 1.81 Inventive Example 63 3.8 4.1 1.83 1.81 Inventive Example 64 3.7 3.9 1.84 1.83 Inventive Example 61′ 4.1 4.3 1.81 1.79 Inventive Example 62′ 3.8 4.0 1.82 1.80 Inventive Example 63′ 3.7 4.0 1.82 1.80 Inventive Example 64′ 3.6 3.8 1.83 1.82 Inventive Example

(40) As shown in Table 13, in Sample Nos. 61 to 64 and 61′ to 64′, the chemical composition was within the range of the invention, and the parameter R in the thickness middle portion was within the range of the invention. Accordingly, good magnetic characteristics were obtained. In Sample Nos. 62, 63, 62′, and 63′ in which the sheet traveling tension was 3 MPa or less, the elastic strain anisotropy was low, and particularly excellent results were obtained in the iron loss W15/50.sub.L, average value W15/50.sub.L+C, magnetic flux density B50.sub.L, and average value B50.sub.L+C. In Sample Nos. 64 and 64′ in which the cooling rate from 920° C. to 700° C. was 1° C./sec or less, the elastic strain anisotropy was further reduced, and more excellent results were obtained in the iron loss W15/50.sub.L, average value W15/50.sub.L+C, magnetic flux density B50.sub.L, and average value B50.sub.L+C. In the measurement of the elastic strain anisotropy, a sample having a quadrangular planar shape in which each side had a length of 55 mm, two sides were parallel to the rolling direction, and two sides were parallel to the direction perpendicular to the rolling direction (sheet width direction) was cut out from each non-oriented electrical steel sheet, and the length of each side after deformation under the influence of elastic strain was measured. Then, it was determined how much the length in the direction perpendicular to the rolling direction was greater than the length in the rolling direction.

(41) (Sixth Test)

(42) In a sixth test, molten steels each having a chemical composition shown in Table 14 were rapidly solidified by a twin roll method to obtain steel strips. In Table 14, the blank indicates that the amount of the corresponding element is less than the detection limit, and the remainder consists of Fe and impurities. In Table 14, the underline indicates that the numerical value is out of the range of the invention. Next, the steel strips were cold rolled and subjected to final annealing to produce various non-oriented electrical steel sheets having a thickness of 0.50 mm. Then, intensities of eight crystal orientations of each non-oriented electrical steel sheet were measured, and a parameter R in a thickness middle portion was calculated. Table 15 shows the results thereof. In Table 15, the underline indicates that the numerical value is out of the range of the invention.

(43) TABLE-US-00016 TABLE 14 Chemical Composition (mass %) Total Content of Coarse Steel Precipitate Sym- Forming Param- bol C Si Al Mn S Mg Ca Sr Ba La Zn Cd Sn Cu Elements eter Q A 0.0014 1.02 0.03 0.20 0.0022 0.0005 0.0005 0.88 B 0.0013 1.05 0.02 0.18 0.0020 0.0007 0.0007 0.91 C 0.0021 1.04 0.03 0.17 0.0019 0.0008 0.0008 0.93 D 0.0025 1.00 0.03 0.18 0.0023 0.0012 0.0012 0.88 E′ 0.0018 1.03 0.04 0.22 0.0024 0.0013 0.0013 0.89 F 0.0019 0.98 0.04 0.17 0.0016 0.0011 0.0011 0.89 G 0.0011 1.07 0.03 0.26 0.0035 0.0004 0.0004 0.87 H 0.0021 1.02 0.03 0.21 0.0020 0.0001 0.0001 0.87 I 0.0022 1.01 0.03 0.19 0.0018 0.0021 0.0021 0.88 J 0.0020 2.46 0.02 0.22 0.0027 0.0007 0.0007 2.28 K 0.0018 1.05 0.03 0.24 0.0022 0.0009 0.0009 0.87 L 0.0016 1.09 0.03 0.21 0.0019 0.0008 0.0008 0.94 M 0.0016 0.98 0.04 0.22 0.0021 0.0009 0.0009 0.84 N 0.0020 1.00 0.03 0.22 0.0018 0.0004 0.0004 0.84 O′ 0.0019 1.02 0.02 0.21 0.0017 0.0006 0.0006 0.85 P 0.0017 1.02 0.02 0.24 0.0024 0.0008 0.0008 0.82 Q 0.0021 1.01 0.04 0.21 0.0022 0.0009 0.0009 0.88 R 0.0024 1.07 0.02 0.22 0.0015 0.0010 0.14 0.0010 0.89 S 0.0022 1.05 0.02 0.24 0.0018 0.0013 0.32 0.0013 0.85 K′ 0.0018 1.05 0.03 0.24 0.0015 0.0009 0.0009 0.87 L′ 0.0016 1.09 0.03 0.21 0.0010 0.0008 0.0008 0.94 M′ 0.0016 0.98 0.04 0.22 0.0005 0.0009 0.0009 0.84 N′ 0.0020 1.00 0.03 0.22 0.0005 0.0010 0.0010 0.84 O″ 0.0019 1.02 0.02 0.21 0.0005 0.0010 0.0010 0.85 P′ 0.0017 1.02 0.02 0.24 0.0005 0.0008 0.0008 0.82 Q′ 0.0021 1.01 0.04 0.21 0.0005 0.0009 0.0009 0.88 R′ 0.0024 1.07 0.02 0.22 0.0005 0.0010 0.14 0.0010 0.89 S′ 0.0022 1.05 0.02 0.24 0.0006 0.0013 0.32 0.0013 0.85 T 0.0018 1.03 0.003 0.21 0.0007 0.0005 0.0005 0.0010 0.83 TT 0.0029 1.98 0.03 1.98 0.0005 0.0010 0.0010 0.06 TTT 0.0010 0.34 0.98 1.42 0.0006 0.0010 0.0010 0.88

(44) TABLE-US-00017 TABLE 15 Sample Steel Crystal Orientation Intensity I Parameter No. Symbol I.sub.100 I.sub.310 I.sub.411 I.sub.521 I.sub.111 I.sub.211 I.sub.332 I.sub.221 R Remarks 101 A 1.03 0.88 0.68 0.43 2.01 2.33 0.48 1.29 0.49 Comparative Example 102 B 1.12 1.05 0.79 0.61 1.63 1.94 0.39 1.14 0.70 Comparative Example 103 C 0.85 0.77 0.47 0.31 2.25 1.56 0.64 1.78 0.39 Comparative Example 104 D 1.06 0.82 0.62 0.57 2.01 1.32 0.53 1.44 0.58 Comparative Example 105 E′ 1.11 1.23 1.08 0.52 2.21 1.65 0.99 1.22 0.65 Comparative Example 106 F 0.98 0.89 1.05 0.29 1.99 1.78 0.67 1.02 0.59 Comparative Example 107 G 1.14 1.01 0.39 0.44 1.78 1.42 0.95 1.07 0.57 Comparative Example 108 H 1.27 0.92 0.66 0.92 1.38 1.58 0.82 1.31 0.74 Comparative Example 109 I 1.19 0.88 0.45 0.70 1.58 1.49 0.54 1.14 0.68 Comparative Example 110 J 1.17 1.04 0.69 0.66 1.49 1.35 0.68 1.33 0.73 Comparative Example 111 K 1.59 0.92 0.83 0.78 0.97 1.29 0.48 0.99 1.10 Inventive Example 112 L 1.62 1.06 1.01 0.66 0.88 1.36 0.37 1.22 1.14 Inventive Example 113 M 1.44 1.22 0.89 0.71 1.02 1.16 0.29 1.08 1.20 Inventive Example 114 N 1.92 0.69 0.95 0.83 1.35 1.62 0.44 1.29 0.93 Inventive Example 115 O′ 1.55 0.88 1.21 0.87 0.87 1.00 0.31 1.45 1.24 Inventive Example 116 P 2.04 0.77 1.33 0.53 1.38 1.77 0.69 1.85 0.82 Inventive Example 117 Q 1.88 1.31 1.04 0.75 1.09 0.98 0.27 1.23 1.39 Inventive Example 118 R 2.63 1.05 1.93 0.43 0.66 0.68 0.66 1.15 1.92 Inventive Example 119 S 2.47 0.99 1.68 0.55 0.78 0.82 0.62 1.12 1.70 Inventive Example 111′ K′ 1.61 0.90 0.81 0.80 0.99 1.27 0.50 0.97 1.10 Inventive Example 112′ L′ 1.64 1.04 0.99 0.68 0.90 1.34 0.39 1.20 1.14 Inventive Example 113′ M′ 1.46 1.20 0.87 0.73 1.04 1.14 0.31 1.06 1.20 Inventive Example 114′ N′ 1.94 0.67 0.93 0.85 1.37 1.60 0.46 1.27 0.93 Inventive Example 115′ O′ 1.57 0.86 1.19 0.89 0.89 0.98 0.33 1.43 1.24 Inventive Example 116′ P′ 2.06 0.75 1.31 0.55 1.40 1.75 0.71 1.83 0.82 Inventive Example 117′ Q′ 1.90 1.29 1.02 0.77 1.11 0.96 0.29 1.21 1.39 Inventive Example 118′ R′ 2.65 1.03 1.91 0.45 0.68 0.66 0.68 1.13 1.92 Inventive Example 119′ S′ 2.49 0.97 1.66 0.57 0.80 0.80 0.64 1.10 1.70 Inventive Example 120 T 1.63 0.88 0.79 0.82 1.01 1.25 0.52 0.95 1.10 Inventive Example 121 TT 1.66 1.02 0.97 0.70 0.92 1.32 0.41 1.18 1.52 Inventive Example 122 TTT 1.48 1.18 0.85 0.75 1.06 1.12 0.33 1.04 0.93 Inventive Example

(45) The magnetic characteristics of each non-oriented electrical steel sheet were measured. Table 16 shows the results thereof. In Table 16, the underline indicates that the numerical value is not within a desired range. That is, the underline in the column of magnetic flux density B50.sub.L indicates that the magnetic flux density is less than 1.79 T, the underline in the column of average value B50.sub.L+C indicates that the average value is less than 1.75 T, the underline in the column of iron loss W15/50.sub.L indicates the iron loss is greater than 4.5 W/kg, and the underline in the column of average value W15/50.sub.L+C indicates that the average value is greater than 5.0 W/kg.

(46) TABLE-US-00018 TABLE 16 Sample W15/50.sub.L W15/50.sub.L+C B50.sub.L B50.sub.L+C No. (W/kg) (W/kg) (T) (T) Remarks 101 5.3 5.7 1.73 1.71 Comparative Example 102 4.9 5.3 1.76 1.73 Comparative Example 103 5.4 5.7 1.73 1.70 Comparative Example 104 5.3 5.6 1.74 1.72 Comparative Example 105 5.1 5.4 1.75 1.71 Comparative Example 106 5.2 5.5 1.74 1.70 Comparative Example 107 5.2 5.6 1.74 1.71 Comparative Example 108 5.2 5.5 1.77 1.73 Comparative Example 109 5.0 5.3 1.75 1.72 Comparative Example 110 3.5 3.8 1.73 1.69 Comparative Example 111 4.2 4.5 1.81 1.78 Inventive Example 112 4.2 4.4 1.81 1.78 Inventive Example 113 4.1 4.4 1.82 1.79 Inventive Example 114 4.4 4.7 1.79 1.77 Inventive Example 115 4.1 4.3 1.82 1.80 Inventive Example 116 4.4 4.8 1.79 1.76 Inventive Example 117 4.1 4.3 1.81 1.79 Inventive Example 118 3.8 4.1 1.83 1.81 Inventive Example 119 4.0 4.2 1.83 1.80 Inventive Example 111′ 4.0 4.3 1.82 1.79 Inventive Example 112′ 4.0 4.2 1.82 1.79 Inventive Example 113′ 3.9 4.2 1.83 1.80 Inventive Example 114′ 4.2 4.5 1.80 1.78 Inventive Example 115′ 3.9 4.1 1.83 1.81 Inventive Example 116′ 4.2 4.6 1.80 1.77 Inventive Example 117′ 3.9 4.1 1.82 1.80 Inventive Example 118′ 3.6 3.9 1.84 1.82 Inventive Example 119′ 3.8 4.0 1.84 1.81 Inventive Example 120 3.8 4.1 1.83 1.80 Inventive Example 121 3.8 4.0 1.83 1.80 Inventive Example 122 3.7 4.0 1.84 1.81 Inventive Example

(47) As shown in Table 16, in Sample Nos. 111 to 122 and 111′ to 119′, the chemical composition was within the range of the invention, and the parameter R in the thickness middle portion was within the range of the invention. Accordingly, good magnetic characteristics were obtained.

(48) In Sample Nos. 101 to 106, since the parameter R in the thickness middle portion was excessively low, the iron loss W15/50.sub.L and the average value W15/50.sub.L+C were high, and the magnetic flux density B50.sub.L and the average value B50.sub.L+C were low. In Sample No. 107, since the S content was excessively high, the iron loss W15/50.sub.L and the average value W15/50.sub.L+C were high, and the magnetic flux density B50.sub.L and the average value B50.sub.L+C were low. In Sample No. 108, since the total amount of the coarse precipitate forming elements was excessively low, the iron loss W15/50.sub.L and the average value W15/50.sub.L+C were high, and the magnetic flux density B50.sub.L and the average value B50.sub.L+C were low. In Sample No. 109, since the total amount of the coarse precipitate forming elements was excessively high, the iron loss W15/50.sub.L and the average value W15/50.sub.L+C were high, and the magnetic flux density B50.sub.L and the average value B50.sub.L+C were low. In Sample No. 110, since the parameter Q was excessively high, the magnetic flux density B50.sub.L and the average value B50.sub.L+C were low.

(49) (Seventh Test)

(50) In a seventh test, molten steels (corresponding to Sample Nos. 131 to 133 in Table 17-1) containing, by mass %, C: 0.0023%, Si: 0.81%, Al: 0.03%, Mn: 0.20%, S: 0.0003%, and Nd: 0.0007% with a remainder consisting of Fe and impurities, and molten steels (corresponding to Sample Nos. 131′ to 133′ in Table 17-1) containing C: 0.0021%, Si: 0.83%, Al: 0.05%, Mn: 0.19%, S: 0.0007%, and Nd: 0.0013% with a remainder consisting of Fe and impurities were rapidly solidified by a twin roll method to obtain steel strips having a thickness of 2.1 mm. In this case, the injection temperature was adjusted to change the columnar grain ratio and the average grain size of the steel strip. Table 17 shows the difference between the injection temperature and the solidification temperature, the columnar grain ratio, and the average grain size. Next, cold rolling was performed at a rolling reduction of 78.2% to obtain a steel sheet having a thickness of 0.50 mm. Thereafter, continuous final annealing was performed for 30 seconds at 850° C. to obtain a non-oriented electrical steel sheet. Then, intensities of eight crystal orientations of each non-oriented electrical steel sheet were measured, and a parameter R in a thickness middle portion was calculated. Table 17 also shows the results thereof. In Table 17, the underline indicates that the numerical value is out of the range of the invention.

(51) TABLE-US-00019 TABLE 17-1 Chemical Composition (mass %) Total Content of Sample Coarse Precipitate Parameter No. C Si Al Mn S Nd Forming Elements Q 131 0.0023 0.81 0.03 0.20 0.0003 0.0007 0.0007 0.67 132 0.0023 0.81 0.03 0.20 0.0003 0.0007 0.0007 0.67 133 0.0023 0.81 0.03 0.20 0.0003 0.0007 0.0007 0.67 131′ 0.0021 0.83 0.05 0.19 0.0007 0.0013 0.0013 0.74 132′ 0.0021 0.83 0.05 0.19 0.0007 0.0013 0.0013 0.74 133′ 0.0021 0.83 0.05 0.19 0.0007 0.0013 0.0013 0.74

(52) TABLE-US-00020 TABLE 17-2 Average Grain Size Temperature Columnar of Steel Sample Difference Grain Ratio Strip Crystal Orientation Intensity I Parameter No. (° C.) (area %) (mm) I.sub.100 I.sub.310 I.sub.411 I.sub.521 I.sub.111 I.sub.211 I.sub.332 I.sub.221 R Remarks 131 13 45 0.18 0.76 0.55 0.49 0.92 1.48 2.02 0.51 1.15 0.53 Comparative Example 132 21 71 0.21 1.11 0.73 0.47 0.89 1.33 1.51 0.48 1.01 0.74 Comparative Example 133 28 86 0.19 1.77 1.29 0.88 0.78 1.19 1.45 0.25 1.18 1.16 Inventive Example 131′ 17 48 0.15 0.77 0.54 0.50 0.91 1.47 2.03 0.50 1.16 0.53 Comparative Example 132′ 36 73 0.19 1.12 0.72 0.48 0.88 1.32 1.52 0.47 1.02 0.74 Comparative Example 133′ 65 85 0.22 1.78 1.28 0.89 0.77 1.18 1.46 0.24 1.19 1.16 Inventive Example

(53) The magnetic characteristics of each non-oriented electrical steel sheet were measured. Table 18 shows the results thereof. In Table 18, the underline indicates that the numerical value is not within a desired range. That is, the underline in the column of magnetic flux density B50.sub.L indicates that the magnetic flux density is less than 1.79 T, the underline in the column of average value B50.sub.L+C indicates that the average value is less than 1.75 T, the underline in the column of iron loss W15/50.sub.L indicates the iron loss is greater than 4.5 W/kg, and the underline in the column of average value W15/50.sub.L+C indicates that the average value is greater than 5.0 W/kg.

(54) TABLE-US-00021 TABLE 18 Sample W15/50.sub.L W15/50.sub.L+C B50.sub.L B50.sub.L+C No. (W/kg) (W/kg) (T) (T) Remarks 131 5.3 5.7 1.75 1.72 Comparative Example 132 5.0 5.5 1.77 1.73 Comparative Example 133 4.4 4.6 1.82 1.80 Inventive Example 131′ 5.2 5.6 1.77 1.74 Comparative Example 132′ 4.9 5.4 1.78 1.74 Comparative Example 133′ 4.3 4.5 1.84 1.82 Inventive Example

(55) As shown in Table 18, in Sample Nos. 133 and 133′ using a steel strip having an appropriate columnar grain ratio, since the parameter R in the thickness middle portion was within the range of the invention, good magnetic characteristics were obtained.

(56) In Sample Nos. 131, 132, 131′, and 132′ using a steel strip having an excessively low columnar grain ratio, the iron loss W15/50.sub.L and the average value W15/50.sub.L+C were high, and the magnetic flux density B50.sub.L and the average value B50.sub.L+C were low.

(57) (Eighth Test)

(58) In an eighth test, molten steels each having a chemical composition shown in Table 19 were rapidly solidified by a twin roll method to obtain steel strips having a thickness of 2.4 mm. The remainder consists of Fe and impurities, and in Table 19, the underline indicates that the numerical value is out of the range of the invention. In this case, the injection temperature and the average cooling rate from completion of the solidification of the molten steel to coiling of the steel strip were adjusted to change the columnar grain ratio and the average grain size of the steel strip. The injection temperature of Sample Nos. 143 to 145 and 143′ to 145′ was 29° C. to 35° C. higher than the solidification temperature, and the average cooling rate from completion of the solidification of the molten steel to coiling of the steel strip was 1,500 to 2,000° C./min. The injection temperature of Sample Nos. 141, 142, 141′, and 142′ was 20° C. to 24° C. higher than the solidification temperature, and the average cooling rate from completion of the solidification of the molten steel to coiling of the steel strip was greater than 3,000° C./min. Table 20 shows the columnar grain ratio and the average grain size. Next, cold rolling was performed at a rolling reduction of 79.2% to obtain a steel sheet having a thickness of 0.50 mm Thereafter, continuous final annealing was performed for 45 seconds at 880° C. to obtain a non-oriented electrical steel sheet. Then, intensities of eight crystal orientations of each non-oriented electrical steel sheet were measured, and a parameter R in a thickness middle portion was calculated. Table 20 also shows the results thereof. In Table 20, the underline indicates that the numerical value is out of the range of the invention.

(59) TABLE-US-00022 TABLE 19 Chemical Composition (mass %) Total Content of Steel Coarse Precipitate Parameter Symbol C Si Al Mn S Cd Forming Elements Q U 0.0025 1.21 0.22 0.33 0.0011 0.0011 0.0011 1.32 V 0.0024 1.24 0.20 0.36 0.0012 0.0010 0.0010 1.28 W 0.0022 1.22 0.18 0.32 0.0009 0.0002 0.0002 1.26 X 0.0027 1.29 0.18 0.37 0.0010 0.0012 0.0012 1.28 Y 0.0021 1.22 0.20 0.31 0.0008 0.0023 0.0023 1.31 U′ 0.0025 1.21 0.22 0.33 0.0005 0.0011 0.0011 1.32 V′ 0.0024 1.24 0.20 0.36 0.0006 0.0010 0.0010 1.28 W′ 0.0022 1.22 0.18 0.32 0.0007 0.0002 0.0002 1.26 X′ 0.0027 1.29 0.18 0.37 0.0005 0.0012 0.0012 1.28 Y′ 0.0021 1.22 0.20 0.31 0.0007 0.0023 0.0023 1.31

(60) TABLE-US-00023 TABLE 20 Average Grain Size Columnar of Steel Sample Steel Grain Ratio Strip Crystal Orientation Intensity I Parameter No. Symbol (area %) (mm) I.sub.100 I.sub.310 I.sub.411 I.sub.521 I.sub.111 I.sub.211 I.sub.332 I.sub.221 R Remarks 141 U 88 0.05 1.23 0.58 1.02 1.32 2.41 2.37 1.02 1.76 0.55 Comparative Example 142 V 87 0.07 1.48 0.74 0.62 0.93 1.97 2.14 0.89 1.19 0.61 Comparative Example 143 W 92 0.16 1.65 0.81 0.73 0.89 2.51 1.84 0.79 1.06 0.66 Comparative Example 144 X 90 0.15 2.11 1.19 1.23 1.04 0.88 1.15 0.67 0.96 1.52 Inventive Example 145 Y 91 0.18 1.48 0.77 0.64 1.01 2.87 2.35 0.75 1.14 0.55 Comparative Example 141′ U′ 90 0.07 1.24 0.57 1.03 1.31 2.40 2.38 1.01 1.77 0.55 Comparative Example 142′ V 88 0.06 1.49 0.73 0.63 0.92 1.96 2.15 0.88 1.20 0.61 Comparative Example 143′ W′ 91 0.15 1.66 0.80 0.74 0.88 2.50 1.85 0.78 1.07 0.66 Comparative Example 144′ X′ 88 0.16 2.12 1.18 1.24 1.03 0.87 1.16 0.66 0.97 1.52 Inventive Example 145′ Y′ 90 0.17 1.49 0.76 0.65 1.00 2.86 2.36 0.74 1.15 0.55 Comparative Example

(61) The magnetic characteristics of each non-oriented electrical steel sheet were measured. Table 21 shows the results thereof. In Table 21, the underline indicates that the numerical value is not within a desired range. That is, the underline in the column of magnetic flux density B50.sub.L indicates that the magnetic flux density is less than 1.79 T, the underline in the column of average value B50.sub.L+C indicates that the average value is less than 1.75 T, the underline in the column of iron loss W15/50.sub.L indicates the iron loss is greater than 4.5 W/kg, and the underline in the column of average value W15/50.sub.L+C indicates that the average value is greater than 5.0 W/kg.

(62) TABLE-US-00024 TABLE 21 Sample W15/50.sub.L W15/50.sub.L+C B50.sub.L B50.sub.L+C No. (W/kg) (W/kg) (T) (T) Remarks 141 5.4 5.8 1.74 1.71 Comparative Example 142 5.1 5.5 1.75 1.73 Comparative Example 143 4.8 5.3 1.77 1.74 Comparative Example 144 3.9 4.2 1.81 1.79 Inventive Example 145 5.0 5.4 1.76 1.73 Comparative Example 141′ 5.3 5.7 1.76 1.73 Comparative Example 142′ 5.0 5.4 1.77 1.74 Comparative Example 143′ 4.7 5.2 1.78 1.74 Comparative Example 144′ 3.8 4.1 1.83 1.81 Inventive Example 145′ 4.9 5.3 1.78 1.74 Comparative Example

(63) As shown in Table 21, in Sample Nos. 144 and 144′ using a steel strip whose chemical composition, columnar grain ratio, and average grain size were appropriate, since the parameter R in the thickness middle portion was within the range of the invention, good magnetic characteristics were obtained.

(64) In Sample Nos. 141, 142, 141′, and 142′ using a steel strip having an excessively small average grain size, the iron loss W15/50.sub.L and the average value W15/50.sub.L+C were high, and the magnetic flux density B50.sub.L and the average value B50.sub.L+C were low. In Sample Nos. 143 and 143′, since the total amount of the coarse precipitate forming elements was excessively low, the iron loss W15/50.sub.L and the average value W15/50.sub.L+C were high, and the magnetic flux density B50.sub.L and the average value B50.sub.L+C were low. In Sample Nos. 145 and 145′, since the total amount of the coarse precipitate forming elements was excessively high, the iron loss W15/50.sub.L and the average value W15/50.sub.L+C were high, and the magnetic flux density B50.sub.L and the average value B50.sub.L+C were low.

(65) (Ninth Test)

(66) In a ninth test, molten steels each having a chemical composition shown in Table 22 were rapidly solidified by a twin roll method to obtain steel strips having a thickness shown in Table 23. In Table 22, the blank indicates that the amount of the corresponding element is less than the detection limit, and the remainder consists of Fe and impurities. In this case, the injection temperature was adjusted to change the columnar grain ratio and the average grain size of the steel strip. The injection temperature was 28° C. to 37° C. higher than the solidification temperature. Table 23 also shows the columnar grain ratio and the average grain size. Next, cold rolling was performed at a rolling reduction shown in Table 23 to obtain a steel sheet having a thickness of 0.20 mm. After that, continuous final annealing was performed for 40 seconds at 830° C. to obtain a non-oriented electrical steel sheet. Then, intensities of eight crystal orientations of each non-oriented electrical steel sheet were measured, and a parameter R in a thickness middle portion was calculated. Table 23 also shows the results thereof. In Table 23, the underline indicates that the numerical value is out of the range of the invention.

(67) TABLE-US-00025 TABLE 22 Chemical Composition (mass %) Total Content of Steel Coarse Precipitate Parameter Symbol C Si Al Mn S Ba Sn Cu Forming Elements Q Z 0.0017 0.53 0.32 0.49 0.0022 0.0007 0.0007 0.68 AA 0.0018 0.54 0.29 0.51 0.0019 0.0008 0.0008 0.61 BB 0.0014 0.51 0.28 0.50 0.0018 0.0008 0.09 0.0008 0.57 CC 0.0016 0.51 0.33 0.47 0.0022 0.0006 0.48 0.0006 0.70 EE 0.0013 0.56 0.30 0.56 0.0021 0.0009 0.0009 0.60 Z′ 0.0017 0.53 0.32 0.49 0.0008 0.0014 0.0014 0.68 AA′ 0.0018 0.54 0.29 0.51 0.0007 0.0013 0.0013 0.61 BB′ 0.0014 0.51 0.28 0.50 0.0005 0.0013 0.09 0.0013 0.57 CC′ 0.0016 0.51 0.33 0.47 0.0007 0.0012 0.48 0.0012 0.70 EE′ 0.0013 0.56 0.30 0.56 0.0008 0.0014 0.0014 0.60

(68) TABLE-US-00026 TABLE 23 Average Thickness Columnar Grain Size of Steel Grain of Steel Rolling Sample Steel Strip Ratio Strip Reduction Crystal Orientation Intensity I Parameter No. Symbol (mm) (area %) (mm) (%) I.sub.100 I.sub.310 I.sub.411 I.sub.521 I.sub.111 I.sub.211 I.sub.332 I.sub.221 R Remarks 151 Z 0.38 92 0.22 47.4 1.33 1.02 0.97 0.65 1.01 1.17 0.29 1.13 1.10 Inventive Example 152 AA 0.62 97 0.21 67.7 1.54 1.20 1.38 0.77 0.95 1.06 0.46 0.89 1.46 Inventive Example 153 BB 0.81 88 0.24 75.4 1.66 1.19 1.51 0.83 0.77 1.01 0.52 0.78 1.69 Inventive Example 154 CC 1.02 90 0.23 80.4 1.59 1.24 1.36 0.94 0.83 1.15 0.42 1.05 1.49 Inventive Example 155 EE 2.24 86 0.21 91.1 1.44 0.87 1.23 0.69 1.84 2.05 0.76 1.18 0.73 Comparative Example 151′ Z′ 0.94 95 0.21 46.8 1.35 1.00 0.99 0.63 0.99 1.19 0.27 1.15 1.10 Inventive Example 152′ AA′ 1.56 98 0.23 67.9 1.56 1.18 1.40 0.75 0.93 1.08 0.44 0.91 1.46 Inventive Example 153′ BB′ 2.01 91 0.22 75.1 1.68 1.17 1.53 0.81 0.75 1.03 0.50 0.80 1.69 Inventive Example 154′ CC′ 2.53 93 0.21 80.2 1.61 1.22 1.38 0.92 0.81 1.17 0.40 1.07 1.49 Inventive Example 155′ EE′ 5.60 88 0.22 91.1 1.46 0.85 1.25 0.67 1.82 2.07 0.74 1.20 0.73 Comparative Example

(69) The magnetic characteristics of each non-oriented electrical steel sheet were measured. Table 24 shows the results thereof. In Table 24, the underline indicates that the numerical value is not within a desired range. That is, the underline in the column of magnetic flux density B50.sub.L indicates that the magnetic flux density is less than 1.79 T, the underline in the column of average value B50.sub.L+C indicates that the average value is less than 1.75 T, the underline in the column of iron loss W15/50.sub.L indicates the iron loss is greater than 4.5 W/kg, and the underline in the column of average value W15/50.sub.L+C indicates that the average value is greater than 5.0 W/kg.

(70) TABLE-US-00027 TABLE 24 Sample W15/50.sub.L W15/50.sub.L+C B50.sub.L B50.sub.L+C No. (W/kg) (W/kg) (T) (T) Remarks 151 4.4 4.6 1.79 1.76 Inventive Example 152 4.2 4.4 1.80 1.77 Inventive Example 153 3.9 4.2 1.83 1.81 Inventive Example 154 4.0 4.3 1.82 1.79 Inventive Example 155 4.8 5.2 1.77 1.73 Comparative Example 151′ 4.3 4.5 1.81 1.78 Inventive Example 152′ 4.1 4.3 1.82 1.79 Inventive Example 153′ 3.8 4.1 1.85 1.83 Inventive Example 154′ 3.9 4.2 1.84 1.81 Inventive Example 155′ 4.7 5.1 1.78 1.74 Comparative Example

(71) As shown in Table 24, in Sample Nos. 151 to 154 and 151′ to 154′ using a steel strip whose chemical composition, columnar grain ratio, and average grain size were appropriate, and cold rolled at an appropriate reduction, since the parameter R in the thickness middle portion was within the range of the invention, good magnetic characteristics were obtained. In Sample Nos. 153, 154, 153′, and 154′ containing an appropriate amount of Sn or Cu, particularly excellent results were obtained in the iron loss W15/50.sub.L, average value W15/50.sub.L+C, magnetic flux density B50.sub.L, and average value B50.sub.L+C.

(72) In Sample Nos. 155 and 155′ in which the rolling reduction of cold rolling was excessively high, the iron loss W15/50.sub.L and the average value W15/50.sub.L+C were high, and the magnetic flux density B50.sub.L and the average value B50.sub.L+C were low.

(73) (Tenth Test)

(74) In a tenth test, molten steels (corresponding to Sample Nos. 161 to 164 in Table 25-1) containing, by mass %, C: 0.0014%, Si: 0.34%, Al: 0.48%, Mn: 1.42%, S: 0.0017%, and Sr: 0.0011% with a remainder consisting of Fe and impurities, and molten steels (corresponding to Sample Nos. 161′ to 164′ in Table 25-1) containing C: 0.0015%, Si: 0.35%, Al: 0.47%, Mn: 1.41%, S: 0.0007%, and Sr: 0.0013% with a remainder consisting of Fe and impurities were rapidly solidified by a twin roll method to obtain steel strips having a thickness of 2.3 mm. In this case, the injection temperature was adjusted to be 32° C. higher than the solidification temperature such that the columnar grain ratio of the steel strip was 90% and the average grain size was 0.17 mm. Next, cold rolling was performed at a rolling reduction of 78.3% to obtain a steel sheet having a thickness of 0.50 mm. Thereafter, continuous final annealing was performed for 20 seconds at 920° C. to obtain a non-oriented electrical steel sheet. In final annealing, the sheet traveling tension and the cooling rate from 920° C. to 700° C. were changed. Table 25 shows the sheet traveling tension and the cooling rate. The crystal orientation intensity of each non-oriented electrical steel sheet was measured, and a parameter R in a thickness middle portion was calculated. Table 25 also shows the results thereof.

(75) TABLE-US-00028 TABLE 25-1 Chemical Composition (mass %) Total Content of Sample Coarse Precipitate No. C Si Al Mn S Sr Forming Elements Parameter Q 161 0.0014 0.34 0.48 1.42 0.0017 0.0011 0.0011 −0.12 162 0.0014 0.34 0.48 1.42 0.0017 0.0011 0.0011 −0.12 163 0.0014 0.34 0.48 1.42 0.0017 0.0011 0.0011 −0.12 164 0.0014 0.34 0.48 1.42 0.0017 0.0011 0.0011 −0.12 161′ 0.0015 0.35 0.47 1.41 0.0007 0.0013 0.0013 −0.12 162′ 0.0015 0.35 0.47 1.41 0.0007 0.0013 0.0013 −0.12 163′ 0.0015 0.35 0.47 1.41 0.0007 0.0013 0.0013 −0.12 164′ 0.0015 0.35 0.47 1.41 0.0007 0.0013 0.0013 −0.12

(76) TABLE-US-00029 TABLE 25-2 Sheet Elastic Traveling Cooling Strain Sample Tension Rate Anisotropy Crystal Orientation Intensity I Parameter No. (MPa) (° C./sec) (%) I.sub.100 I.sub.310 I.sub.411 I.sub.521 I.sub.111 I.sub.211 I.sub.332 I.sub.221 R Remarks 161 4.5 2.3 1.18 1.39 0.96 1.35 1.00 1.55 0.64 1.18 1.69 0.93 Inventive Example 162 2.6 2.6 1.09 1.56 1.04 1.55 1.21 1.38 0.71 1.17 1.38 1.16 Inventive Example 163 1.8 2.4 1.07 1.87 1.11 1.61 1.13 1.30 0.59 1.21 1.41 1.27 Inventive Example 164 1.6 0.7 1.03 2.38 1.18 2.16 1.22 1.21 0.66 1.09 1.36 1.61 Inventive Example 161′ 4.3 2.4 1.17 1.40 0.95 1.36 0.99 1.54 0.65 1.17 1.70 0.93 Inventive Example 162′ 2.5 2.5 1.10 1.57 1.03 1.56 1.20 1.37 0.72 1.16 1.39 1.16 Inventive Example 163′ 1.5 2.3 1.06 1.88 1.10 1.62 1.12 1.29 0.60 1.20 1.42 1.27 Inventive Example 164′ 1.7 0.6 1.04 2.39 1.17 2.17 1.21 1.20 0.67 1.08 1.37 1.61 Inventive Example

(77) The magnetic characteristics of each non-oriented electrical steel sheet were measured. Table 26 shows the results thereof.

(78) TABLE-US-00030 TABLE 26 Sample W15/50.sub.L W15/50.sub.L+C B50.sub.L B50.sub.L+C No. (W/kg) (W/kg) (T) (T) Remarks 161 4.2 4.4 1.82 1.80 Inventive Example 162 3.9 4.1 1.83 1.81 Inventive Example 163 3.8 4.1 1.83 1.81 Inventive Example 164 3.7 3.9 1.84 1.83 Inventive Example 161′ 4.1 4.3 1.84 1.82 Inventive Example 162′ 3.8 4.0 1.85 1.83 Inventive Example 163′ 3.7 4.0 1.85 1.83 Inventive Example 164′ 3.6 3.8 1.86 1.85 Inventive Example

(79) As shown in Table 26, in Sample Nos. 161 to 164 and 161′ to 164′, the chemical composition was within the range of the invention, and the parameter R in the thickness middle portion was within the range of the invention. Accordingly, good magnetic characteristics were obtained. In Sample Nos. 162, 163, 162′, and 163′ in which the sheet traveling tension was 3 MPa or less, the elastic strain anisotropy was low, and particularly excellent results were obtained in the iron loss W15/50.sub.L, average value W15/50.sub.L+C, magnetic flux density B50.sub.L, and average value B50.sub.L+C. In Sample Nos. 164 and 164′ in which the cooling rate from 920° C. to 700° C. was 1° C./sec or less, the elastic strain anisotropy was further reduced, and more excellent results were obtained in the iron loss W15/50.sub.L, average value W15/50.sub.L+C, magnetic flux density B50.sub.L, and average value B50.sub.L+C. In the measurement of the elastic strain anisotropy, a sample having a quadrangular planar shape in which each side had a length of 55 mm, two sides were parallel to the rolling direction, and two sides were parallel to the direction perpendicular to the rolling direction (sheet width direction) was cut out from each non-oriented electrical steel sheet, and the length of each side after deformation under the influence of elastic strain was measured. Then, it was determined how much the length in the direction perpendicular to the rolling direction was greater than the length in the rolling direction.

INDUSTRIAL APPLICABILITY

(80) The invention can be used in, for example, manufacturing industries for non-oriented electrical steel sheets and industries using non-oriented electrical steel sheets.