GRAIN-ORIENTED ELECTRIC STEEL SHEET AND MANUFACTURING METHOD THEREFOR

Abstract

A grain-oriented electrical steel sheet according to an embodiment of the present invention includes: Si at 2.0 to 6.0 wt%, Mn at 0.12 to 1.0 wt%, Sb at 0.01 to 0.05 wt%, Sn at 0.03 to 0.08 wt%, Cr at 0.01 to 0.2 wt%, and the balance of Fe and inevitable impurities, and satisfies Formula 1 below.

4×[Cr]−0.1×[Mn]≥0.5×([Sn]+[Sb])   [Formula 1]

(In Formula 1, [Cr], [Mn], [Sn], and [Sb] represent contents (wt%) of Cr, Mn, Sn, and Sb, respectively.)

Claims

1. A grain-oriented electrical steel sheet includes: Si at 2.0 to 6.0 wt%, Mn at 0.12 to 1.0 wt%, Sb at 0.01 to 0.05 wt%, Sn at 0.03 to 0.08 wt%, Cr at 0.01 to 0.2 wt%, and the balance of Fe and inevitable impurities, and satisfies Formula 1 below:
4×[Cr]−0.1×[Mn]≥0.5×([Sn]+[Sb])   [Formula 1] (in Formula 1, [Cr], [Mn], [Sn], and [Sb] represent contents (wt%) of Cr, Mn, Sn, and Sb, respectively).

2. The grain-oriented electrical steel sheet of claim 1, further comprising Al at 0.005 to 0.04 wt% and P at 0.005 to 0.045 wt%.

3. The grain-oriented electrical steel sheet of claim 1, further comprising Co at 0.1 wt% or less.

4. The grain-oriented electrical steel sheet of claim 1, further comprising C at 0.01 wt% or less, N at 0.01 wt% or less, and S at 0.01 wt% or less.

5. A manufacturing method of a grain-oriented electrical steel sheet, comprising: heating a slab including Si at 2.0 to 6.0 wt%, C at 0.01 to 0.15 wt%, Mn at 0.12 to 1.0 wt%, Sb at 0.01 to 0.05 wt%, Sn at 0.03 to 0.08 wt%, Cr at 0.01 to 0.2 wt%, and the balance of Fe and inevitable impurities, and satisfying Formula 1 below; hot-rolling the slab to manufacture a hot rolled sheet; cold-rolling the hot-rolled sheet to produce a cold-rolled sheet; primary recrystallization annealing the cold-rolled sheet; and secondary recrystallization annealing the cold-rolled sheet subjected to the primary recrystallization annealing
4×[Cr]−0.1×[Mn]≥0.5×([Sn]+[Sb])   [Formula 1] (in Formula 1, [Cr], [Mn], [Sn], and [Sb] represent contents (wt%) of Cr, Mn, Sn, and Sb, respectively).

6. The manufacturing method of the grain-oriented electrical steel sheet of claim 5, wherein the slab satisfies Formula 2:
2×(1.3−[Mn])−2×(3.4−[Si])≤50×[C]≤3×(1.3−[Mn])−2×(3.4−[Si])   [Formula 2] (in Formula 2, [Mn], [Si], and [C] represent contents (wt%) of Mn, Si, and C in the slab, respectively).

7. The manufacturing method of the grain-oriented electrical steel sheet of claim 5, wherein the slab satisfies Formula 3:
5×(1.3−[Mn])−4×(3.4−[Si])−0.5 ≤100×[C]≤5×(1.3−[Mn])−4×(3.4−[Si])+0.5   [Formula 3] (in Formula 3, [Mn], [Si]. and [C] represent contents (wt%) of Mn, Si, and C in the slab, respectively).

8. The manufacturing method of the grain-oriented electrical steel sheet of claim 5, wherein the heating of the slab includes heating at a temperature of 1250° C. or less.

9. The manufacturing method of the grain-oriented electrical steel sheet of claim 5, wherein after the manufacturing of the hot-rolled sheet, annealing the hot-rolled sheet is further included, wherein a crack temperature of the annealing of the hot rolled sheet is 800 to 1300° C.

10. The manufacturing method of the grain-oriented electrical steel sheet of claim 5, wherein the manufacturing of the cold-rolled sheet includes cold-rolling once, or cold-rolling two times or more including intermediate annealing.

11. The manufacturing method of the grain-oriented electrical steel sheet of claim 5, wherein the primary recrystallization annealing includes decarburizing and nitriding, and the nitriding is performed after the decarburizing, or the decarburizing is performed after the nitriding, or the decarburizing and the nitriding are simultaneously performed.

12. The manufacturing method of the grain-oriented electrical steel sheet of claim 5, further comprising after the primary recrystallization annealing, applying an annealing separating agent.

13. The manufacturing method of the grain-oriented electrical steel sheet of claim 5, wherein the secondary recrystallization annealing includes completing secondary recrystallization at a temperature of 900 to 1210° C.

Description

EXAMPLE 1

[0081] A slab that includes Si at 3.4 wt%, S at 0.004 wt%, N at 0.004 wt%, Al at 0.029 wt%, P at 0.032 wt%; Mn, C, Sn, Sb, and Cr changed as shown in Table 1 below; and the balance of Fe and inevitable impurities was heated at a temperature of 1140° C., and then hot-rolled to a thickness of 2.3 mm. The hot-rolled sheet was heated at a temperature of 1080° C., maintained at 910° C. for 160 seconds, and quenched in water. The hot-rolled annealing sheet was pickled and rolled once to a thickness of 0.23 mm, and the cold-rolled sheet was maintained for 200 seconds in a humid hydrogen, nitrogen, and ammonia mixed gas atmosphere at a temperature of 850° C., and then simultaneously decarbonized, nitrided, annealed, and heat-treated so that the nitrogen content was 190 ppm and the carbon content was 30 ppm.

[0082] The final annealing was performed by applying MgO, an annealing separating agent, to this steel sheet, and in this case, the final annealing was performed in a mixed atmosphere of 25 vol% nitrogen+75 vol% hydrogen until 1200° C., and after reaching 1200° C., it was maintained for 10 hours or more in a 100 vol% hydrogen atmosphere and then furnace-cooled. Table 2 shows the measured magnetic characteristics for each condition.

TABLE-US-00001 TABLE 1 Steel type (wt %) Mn C Sb Sn Cr Remarks 1 0.5 0.04 0.02 0.07 0.04 Inventive material 2 0.51 0.04 0.02 0.07 0.07 Inventive material 3 0.49 0.04 0.01 0.03 0.01 Comparative material 4 0.52 0.04 0.05 0.03 0.09 Inventive material 5 0.5 0.04 0.01 0.05 0.01 Comparative material 6 0.49 0.04 0.05 0.05 0.05 Inventive material 7 0.71 0.03 0.02 0.07 0.04 Inventive material 8 0.7 0.03 0.02 0.07 0.07 Inventive material 9 0.72 0.03 0.04 0.03 0.01 Comparative material 10 0.72 0.03 0.05 0.03 0.09 Inventive material 11 0.69 0.03 0.01 0.05 0.01 Comparative material 12 0.71 0.03 0.05 0.05 0.05 Inventive material 13 0.92 0.028 0.02 0.07 0.04 Inventive material 14 0.91 0.028 0.02 0.07 0.07 Inventive material 15 0.92 0.028 0.04 0.03 0.02 Comparative material 16 0.9 0.028 0.05 0.03 0.09 Inventive material 17 0.91 0.028 0.01 0.05 0.02 Comparative material

TABLE-US-00002 TABLE 2 Whether Whether Magnetic Formula Formula Iron loss flux Steel type 4 × [Cr]- 0.5 × 2 is 3 is (W17/50, density (wt %) 0.1 × [Mn] ([Sn] + [Sb]) satisfied satisfied W/kg) (B8, T) 1 0.11 0.045 O O 0.814 1.909 Inventive material 2 0.229 0.045 O O 0.817 1.908 Inventive material 3 −0.009 0.02 O O 0.879 1.871 Comparative material 4 0.308 0.04 O O 0.815 1.899 Inventive material 5 −0.01 0.03 O O 0.889 1.888 Comparative material 6 0.151 0.05 O O 0.817 1.906 Inventive material 7 0.089 0.045 O O 0.813 1.894 Inventive material 8 0.21 0.045 O O 0.808 1.894 Inventive material 9 −0.032 0.035 O O 0.875 1.88 Comparative material 10 0.288 0.04 O O 0.811 1.907 Inventive material 11 −0.029 0.03 O O 0.887 1.884 Comparative material 12 0.129 0.05 O O 0.804 1.913 Inventive material 13 0.068 0.045 X X 0.823 1.887 Inventive material 14 0.189 0.045 X X 0.817 1.895 Inventive material 15 −0.012 0.035 X X 0.879 1.882 Comparative material 16 0.27 0.04 X X 0.807 1.898 Inventive material 17 −0.011 0.03 X X 0.878 1.879 Comparative material

[0083] As shown in Table 1 and Table 2, it can be confirmed that the inventive material in which the relationship between Mn, Cr, Sn, and Sb is properly controlled has excellent magnetism. Meanwhile, it can be seen that the comparative material that does not satisfy the relationship between Mn, Cr, Sn, and Sb has poor magnetism.

EXAMPLE 2

[0084] A slab that includes Si at 3.3 wt%, Mn at 0.3 wt%, Al at 0.026 wt%, N at 0.004 wt%, S at 0.004 wt%, Sb at 0.03 wt%, Sn at 0.06 wt%, P at 0.03 wt%, Cr at 0.04 wt%, Co at 0.02 wt%; the content of C changed as shown in Table 3; and the balance of Fe and other inevitable impurities was heated at a temperature of 1150° C. and then hot-rolled to a thickness of 2.3 mm. The hot-rolled sheet was heated at a temperature of 1080° C., maintained at 890° C. for 160 seconds, and quenched in water. The hot-rolled annealing sheet was pickled and rolled once to a thickness of 0.23 mm, and the cold-rolled sheet was maintained for 200 seconds in a humid hydrogen, nitrogen, and ammonia mixed gas atmosphere at a temperature of 860° C., and then simultaneously decarbonitized, nitrided, annealed, and heat-treated so that the nitrogen content was 180 ppm and the carbon content was 30 ppm.

[0085] The final annealing was performed by applying MgO, an annealing separating agent, to this steel sheet, and in this case, the final annealing was performed in a mixed atmosphere of 25 vol% nitrogen+75 vol% hydrogen until 1200° C., and after reaching 1200° C., it was maintained for 10 hours or more in a 100 vol% hydrogen atmosphere and then furnace-cooled. Table 3 shows the measured magnetic characteristics for each condition.

TABLE-US-00003 TABLE 3 Whether Whether Magnetic Steel Formula 2 is Formula 3 is Iron loss flux density type C satisfied satisfied (W17/50) B8 18 0.014 X X 0.889 1.898 19 0.021 X X 0.887 1.902 20 0.023 X X 0.882 1.902 21 0.026 X X 0.874 1.902 22 0.028 X X 0.878 1.897 23 0.031 X X 0.872 1.898 24 0.033 X X 0.865 1.901 25 0.035 X X 0.846 1.899 26 0.038 ◯ X 0.828 1.912 27 0.04 ◯ X 0.821 1.923 28 0.041 ◯ ◯ 0.816 1.923 29 0.044 ◯ ◯ 0.811 1.915 30 0.046 ◯ ◯ 0.815 1.922 31 0.049 ◯ ◯ 0.822 1.922 32 0.052 ◯ X 0.823 1.915 33 0.054 ◯ X 0.813 1.92 34 0.058 X X 0.845 1.909 35 0.059 X X 0.857 1.907 36 0.062 X X 0.887 1.907 37 0.065 X X 0.884 1.891 38 0.067 X X 0.881 1.899 39 0.068 X X 0.877 1.901 40 0.071 X X 0.871 1.898 41 0.074 X X 0.879 1.898

[0086] As shown in Table 3, it can be confirmed that among the invention materials, the invention material that satisfies Formula 2 has more excellent magnetism. In addition, it can be confirmed that among the invention materials that satisfy Formula 2, the invention material that simultaneously satisfies Formula 3 has more excellent magnetism.

EXAMPLE 3

[0087] A slab that includes Si at 3.4 wt%, Al at 0.027 wt%, N at 0.005 wt%, S at 0.004 wt%, Sb at 0.02 wt%, Sn at 0.07 wt%, P at 0.03 wt%, Cr at 0.04 wt%, Co at 0.03 wt%; the contents of C and Mn changed as shown in Table 4; and the balance of Fe and other inevitable impurities was heated at a temperature of 1150° C. and then hot-rolled to a thickness of 2.3 mm. The hot-rolled sheet was heated at a temperature of 1080° C., maintained at 890° C. for 160 seconds, and quenched in water. The hot-rolled annealing sheet was pickled and rolled once to a thickness of 0.23 mm, and the cold-rolled sheet was maintained for 200 seconds in a humid hydrogen, nitrogen, and ammonia mixed gas atmosphere at a temperature of 860° C., and then simultaneously decarbonitized, nitrided, annealed, and heat-treated so that the nitrogen content was 180 ppm and the carbon content was 30 ppm.

[0088] The final annealing was performed by applying MgO, an annealing separating agent, to this steel sheet, and in this case, the final annealing was performed in a mixed atmosphere of 25 vol% nitrogen+75 vol% hydrogen until 1200° C., and after reaching 1200° C., it was maintained for 10 hours or more in a 100 vol% hydrogen atmosphere and then furnace-cooled. Table 4 shows the measured magnetic characteristics for each condition.

TABLE-US-00004 TABLE 4 Mag- Whether Whether Iron netic Formula Formula loss flux Steel 2 is 3 is (W17/ density type Mn C satisfied satisfied 50) B8 42 0.09 0.041 X X 0.874 1.906 Comparative material 43 0.11 0.076 X X 0.871 1.906 Comparative material 44 0.2 0.036 X X 0.873 1.904 Inventive material 45 0.22 0.054 O O 0.822 1.905 Inventive material 46 0.21 0.074 X X 0.881 1.901 Inventive material 47 0.31 0.034 X X 0.884 1.889 Inventive material 48 0.29 0.05 O O 0.812 1.909 Inventive material 49 0.31 0.066 X X 0.877 1.898 Inventive material 50 0.41 0.027 X X 0.882 1.902 Inventive material 51 0.4 0.045 O O 0.827 1.917 Inventive material 52 0.4 0.062 X X 0.879 1.897 Inventive material 53 0.5 0.023 X X 0.871 1.883 Inventive material 54 0.5 0.04 O O 0.816 1.908 Inventive material 55 0.52 0.052 X X 0.881 1.892 Inventive material 56 0.61 0.021 X X 0.879 1.89 Inventive material 57 0.61 0.034 O O 0.816 1.895 Inventive material 58 0.61 0.048 X X 0.887 1.891 Inventive material 59 0.72 0.016 X X 0.884 1.875 Inventive material 60 0.71 0.03 O O 0.815 1.891 Inventive material 61 0.7 0.043 X X 0.881 1.882 Inventive material 62 0.8 0.01 X X 0.882 1.876 Inventive material 63 0.81 0.024 O O 0.826 1.887 Inventive material 64 0.81 0.037 X X 0.888 1.874 Inventive material 65 0.89 0.008 X X 0.883 1.875 Inventive material 66 0.90 0.021 O O 0.823 1.887 Inventive material 67 0.98 0.029 X X 0.871 1.881 Inventive material 68 1.07 0.002 X X 0.876 1.872 Comparative material 69 1.1 0.01 O O 0.889 1.874 Comparative material 70 1.09 0.023 X X 0.883 1.871 Comparative material

[0089] As shown in Table 4, it can be confirmed that among the invention materials, the invention material that satisfies Formula 2 and Formula 3 has more excellent magnetism.

[0090] The present invention may be embodied in many different forms, and should not be construed as being limited to the disclosed embodiments and/or examples. In addition, it will be understood by those skilled in the art that various changes in form and details may be made thereto without departing from the technical spirit and essential features of the present invention. Therefore, it is to be understood that the above-described embodiments and/or examples are for illustrative purposes only, and the scope of the present invention is not limited thereto.