NON-ORIENTED ELECTRICAL STEEL SHEET HAVING AN EXCELLENT HIGH-FREQUENCY IRON LOSS PROPERTY

A non-oriented electrical steel sheet has a chemical composition that includes C: not more than 0.005%, Si: 1.5-4%, Mn: 1.0-5%, P: not more than 0.1%, S: not more than 0.005%, Al: not more than 3 mass %, N: not more than 0.005 mass %, Bi: not more than 0.0030% as mass % and the remainder being Fe and inevitable impurities or a chemical composition containing C: not more than 0.005%, Si: 1.5-4%, Mn: 1.0-5%, P: not more than 0.1%, S: not more than 0.005%, Al: not more than 3 mass %, N: not more than 0.005 mass %, Bi: not more than 0.0030% and further one or two of Ca: 0.0005-0.005% and Mg: 0.0002-0.005%, and is stably excellent in the high-frequency iron loss property even if a great amount of Mn is included.

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Description
TECHNICAL FIELD

This disclosure relates to a non-oriented electrical steel sheet having an excellent high-frequency iron loss property.

BACKGROUND

A motor for a hybrid car or an electric car is driven at a high frequency region of 400-2 kHz from a viewpoint of miniaturization and high efficiency. A non-oriented electrical steel sheet used in a core material for such a high-frequency motor is desired to be low in iron loss at a high frequency.

It is effective to decrease sheet thickness and increase specific resistance to reduce the iron loss at a high frequency. In the method of decreasing the sheet thickness, however, not only handling becomes difficult due to a decrease in rigidity in the materials, but also the number of punching steps or lamination steps is increased, so that there is a problem of deteriorating productivity. On the contrary, the method of increasing the specific resistance does not have the above disadvantage, so that it can be said to be desirable as a method of reducing high-frequency iron loss.

Addition of Si is effective to increase the specific resistance. However, Si is an element having a large solid-solution strengthening ability so that there is a problem that the material is hardened with the increase in the amount of Si to deteriorate the rolling property. As one means to solve the above problem, there is a method of adding Mn instead of Si. Since Mn is small in its solid-solution strengthening ability compared to Si, the high-frequency iron loss can be reduced while suppressing deterioration of productivity.

As a technique of utilizing the above effect by Mn addition, for example, JP 2002-47542 A discloses a non-oriented electrical steel sheet containing Si: 0.5-2.5 mass %, Mn: 1.0-3.5 mass % and Al: 1.0-3.0 mass %. Also, JP 2002-30397 A discloses a non-oriented electrical steel sheet containing Si: not more than 3.0 mass %, Mn: 1.0-4.0 mass % and Al: 1.0-3.0 mass %.

However, the techniques disclosed in JP 2002-47542 A and JP 2002-30397 A have a problem that hysteresis loss is increased with the increase of Mn addition amount and, hence, the desired effect of reducing iron loss may not be obtained.

It could therefore be helpful to provide a non-oriented electrical steel sheet having a stable and excellent high-frequency iron loss property even if a great amount of Mn is contained.

SUMMARY

We found that the deterioration of high-frequency iron loss property in high Mn-added steels is based on the presence of Bi included as an impurity and, hence, the high frequency iron loss can be reduced stably by suppressing the Bi content even at a high Mn content.

We thus provide a non-oriented electrical steel sheet having a chemical composition comprising C: not more than 0.005 mass %, Si: 1.5-4 mass %, Mn: 1.0-5 mass %, P: not more than 0.1 mass %, S: not more than 0.005 mass %, Al: not more than 3 mass %, N: not more than 0.005 mass %, Bi: not more than 0.0030 mass % and the remainder being Fe and inevitable impurities.

The non-oriented electrical steel sheet may contain one or two of Ca: 0.0005-0.005 mass % and Mg: 0.0002-0.005 mass % in addition to the above chemical composition.

Also, the non-oriented electrical steel sheet may further contain one or two of Sb: 0.0005-0.05 mass % and Sn: 0.0005-0.05 mass % in addition to the above chemical composition.

Further, the non-oriented electrical steel sheet may further contain Mo: 0.0005-0.0030 mass % in addition to the above chemical composition.

Moreover, the non-oriented electrical steel sheet may still further contain Ti: not more than 0.002 mass %.

It is thus possible to produce a non-oriented electrical steel sheet having an excellent high-frequency iron loss property stably by suppressing the content of Bi included as an impurity even with a high Mn addition amount.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the influence of Bi content upon the relationship between Mn content and high-frequency iron loss W10/400.

FIG. 2 is a graph showing the relationship between Bi content and high-frequency iron loss W10/400.

 DETAILED DESCRIPTION

Experiments concerning our steel sheets and methods will first be described.

A steel containing C: 0.0016 mass %, Si: 3.35 mass %, P: 0.013 mass %, S: 0.0004 mass %, Al: 1.4 mass % and N: 0.0018 mass % and added with Mn changed within a range of 0.1-5.2 mass % is melted in a laboratory to form a steel ingot, which is hot rolled, subjected to a hot band annealing at 1000° C. in an atmosphere of 100 vol % N2 for 30 seconds, cold rolled to a cold rolled sheet of 0.30 mm in thickness and subjected to a final annealing at 1000° C. in an atmosphere of 20 vol % H2-80 vol % N2 for 30 seconds.

In FIG. 1, symbol  shows the above experimental results as the relationship between Mn addition amount and iron loss W10/400. As seen from these results, when Mn is less than 1 mass %, the iron loss is decreased with the increase in Mn addition amount, but the decrease of the iron loss becomes gentle at an amount of not less than 1 mass % and, rather, the iron loss is increased at an amount exceeding 4 mass %. When the steel sheet containing 2 mass % of Mn is observed by TEM, granular Bi is found in grain boundaries.

To further investigate the influence of Bi upon the magnetic properties, a steel prepared by adding Mn variously changed within a range of 0.1-5.2 mass % to a high-purity steel containing C: 0.0014 mass %, Si: 3.33 mass %, Al: 1.2 mass %, P: 0.014 mass %, S: 0.0006 mass %, N: 0.0020 mass % and Bi: not more than 0.0010 mass % is melted in a laboratory and shaped into a cold rolled and annealed sheet in the same manner as in the above experiment to measure an iron loss W10/400.

The thus obtained experimental results are shown by symbol ▴ in FIG. 1. As seen from these results, the iron loss is reduced with the increase in the Mn addition amount in the cold rolled and annealed sheet made from a high-purity steel having a decreased Bi content as compared to the steel sheet shown by symbol . When the steel sheet containing 2 mass % of Mn is observed by TEM, granular Bi is not found in the grain boundaries. From this fact, we believe that the increase of the iron loss associated with the increase of Mn addition amount in the steel sheet of symbol  is based on the increase of hysteresis loss due to fine precipitation of Bi.

In the steel sheet containing less than 1 mass % of Mn, the effect of improving the iron loss by the decrease in Bi is found, but the ratio thereof is small. Although the reason is not clear sufficiently, we believe that the driving force for grain growth is lowered by solute drag of Mn in the steels having an increased Mn amount and, hence, the grain growth is easily and largely influenced by the presence of fine Bi.

In general, Bi is an impurity incorporated from scrap so that not only the amount incorporated, but also the deviation thereof becomes gradually large associated with the increased use of scrap in recent years. Such an increase of Bi content is not a big problem in electrical steel sheets having a low Mn content, but the steels having a high Mn content are largely influenced by a slight amount of Bi because the grain growth is lowered by solute drag of Mn.

To investigate the influence of Bi content on the iron loss, a steel prepared by adding Bi variously changed within a range of tr. to 0.0045 mass % to a steel containing C: 0.0022 mass %, Si: 3.20 mass %, Mn: 1.7 mass %, Al: 1.3 mass %, P: 0.014 mass %, S: 0.0005 mass % and N: 0.0020 mass % is melted in a laboratory and shaped into a cold rolled and annealed sheet of 0.30 mm in thickness in the same manner as in the above experiment to measure an iron loss W10/400.

FIG. 2 shows the above experimental results as the relationship between Bi content and iron loss W10/400. As seen from FIG. 2, the iron loss largely decreases when the Bi content is not more than 0.0030 mass % (not more than 30 massppm). This is due to the fact that the grain growth is improved by decreasing Bi. From this fact, we confirmed that the Bi content needs to be decreased to not more than 0.0030 mass % to suppress the bad influence of Bi upon grain growth.

There will be described the chemical composition in the non-oriented electrical steel sheet.

C: Not More than 0.005 mass %

C is an element forming a carbide with Mn. When it exceeds 0.005 mass %, the amount of Mn-based carbide is increased to block the grain growth, so that an upper limit is 0.005 mass %. Preferably, it is not more than 0.002 mass %.

Si: 1.5-4 mass %

Si is an element effective to increase the specific resistance of steel and reducing iron loss and is added in an amount of not less than 1.5 mass %. While when it is added in an amount exceeding 4 mass %, the magnetic flux density is lowered, so that an upper limit is 4 mass %. Preferably, the lower limit of Si is 2.0 mass % and the upper limit thereof is 3.0 mass %.

Mn: 1.0-5 mass %

Mn is effective in increasing the specific resistance of steel and reducing an iron loss without largely damaging the workability and is an important ingredient added in an amount of not less than 1.0 mass %. To further obtain the effect of reducing iron loss, it is preferable to be added in an amount of not less than 1.6 mass %. While when it is added in an amount exceeding 5 mass %, the magnetic flux density is lowered, so that an upper limit is 5 mass %. Preferably, the lower limit of Mn is 2 mass % and the upper limit thereof is 3 mass %.

P: Not More than 0.1 mass %

P is an element having a large solid-solution strengthening ability, but when it is added in an amount exceeding 0.1 mass %, the steel sheet is significantly hardened to deteriorate productivity, so that it is limited to not more than 0.1 mass %. Preferably, it is not more than 0.05 mass %.

S: Not More than 0.005 mass %

S is an inevitable impurity. When it is included in an amount exceeding 0.005 mass %, MnS is precipitated to block the grain growth and increase iron loss, so that an upper limit is 0.005 mass %. Preferably, it is not more than 0.001 mass %.

Al: Not More than 3 mass %

Al is an element effective to increase the specific resistance of steel and reducing iron loss like Si. When it is added in an amount exceeding 3 mass %, the magnetic flux density is lowered, so that an upper limit is 3 mass %. Preferably, it is not more than 2 mass %. However, when Al content is less than 0.1 mass %, fine AN is precipitated to block grain growth and increase iron loss, so that a lower limit is preferable to be 0.1 mass %.

N: Not More than 0.005 mass %

N is an inevitable impurity penetrated from ambient air into steel. When the content is large, grain growth is blocked due to the precipitation of AlN to increase the iron loss, so that an upper limit is restricted to 0.005 mass %. Preferably, it is not more than 0.003 mass %.

Bi: Not More than 0.0030 mass %

Bi is an important element to be controlled because it badly affects the high-frequency iron loss property. When Bi content exceeds 0.0030 mass % as seen from FIG. 2, the iron loss violently increases. Therefore, Bi is restricted to not more than 0.0030 mass %. Preferably, it is not more than 0.0010 mass %.

The non-oriented electrical steel sheet preferably contains one or two of Ca and Mg in addition to the above chemical composition.

Ca: 0.0005-0.005 mass %

Ca is an element effective in forming a sulfide and coarsening by compositely precipitating with Bi to suppress the adverse effect of Bi and reduce iron loss. It is preferable to be added in an amount of not less than 0.0005 mass % to obtain such an effect. However, when it is added in an amount exceeding 0.005 mass %, the amount of CaS precipitated becomes too large and iron loss is adversely increased, so that an upper limit is preferable to be 0.005 mass %. More preferably, the lower limit of Ca is 0.001 mass % and the upper limit thereof is 0.004 mass %.

Mg: 0.0002-0.005 mass %

Mg is an element effective in forming an oxide and coarsening by compositely precipitating with Bi to suppress the adverse effect of Bi and reduce iron loss. It is preferable to be added in an amount of not less than 0.0002 mass % to obtain such an effect. However, addition exceeding 0.005 mass % is difficult and brings about an increase in cost, so that an upper limit is preferable to be 0.005 mass %. More preferably, the lower limit of Mg is 0.001 mass % and the upper limit thereof is 0.004 mass %.

Also, the non-oriented electrical steel sheet preferably further contains the following ingredients in addition to the above chemical composition.

Sb: 0.0005-0.05 mass %, Sn: 0.0005-0.05 mass %

Sb and Sn have an effect of improving the texture to increase the magnetic flux density, so that they can be added in an amount of not less than 0.0005 mass % alone or in admixture. More preferably, it is not less than 0.01 mass %. However, addition exceeding 0.05 mass % brings about embrittlement of the steel sheet, so that an upper limit is preferable to be 0.05 mass %. More preferably, the lower limit of each of Sb and Sn is 0.01 mass % and the upper limit thereof is 0.04 mass %.

Mo: 0.0005-0.0030 mass %

Mo has an effect of coarsening the resulting carbide to reduce iron loss and is preferably added in an amount of not less than 0.0005 mass %. However, when it is added in an amount exceeding 0.0030 mass %, the amount of the carbide becomes too large and the iron loss is rather increased, so that an upper limit is preferable to be 0.0030 mass %. More preferably, the lower limit of Mo is 0.0010 mass % and the upper limit thereof is 0.0020 mass %.

Ti: Not More than 0.002 mass %

Ti is an element forming a carbonitride. When the content is large, the amount of the carbonitride precipitated becomes too large, so that the grain growth is blocked and the iron loss is increased. Therefore, Ti is preferably restricted to not more than 0.002 mass %. More preferably, it is not more than 0.001 mass %.

In the non-oriented electrical steel sheet, the remainder other than the aforementioned ingredients is Fe and inevitable impurities. However, other elements may be included within a range not damaging the desired effect.

Next, our production method of our non-oriented electrical steel sheet will be described below.

In the method of producing the non-oriented electrical steel sheet, conditions are not particularly limited except that the chemical composition of the steel sheet is controlled within our defined range, so that production may be performed under the same conditions as in the normal non-oriented electrical steel sheet. For example, the steel sheet can be produced by a method wherein a steel having a chemical composition is melted, for example, in a converter, a degassing device or the like and shaped into a raw steel material (slab) by a continuous casting method or an ingot making-blooming method, which is hot rolled, subjected to a hot band annealing as required and further to a single cold rolling or two or more cold rollings including an intermediate annealing therebetween to a predetermined sheet thickness and subsequently to a final annealing.

EXAMPLES

A steel having a chemical composition shown in Table 1 is melted in a converter, degassed by blowing and continuously cast into a slab, which is heated at 1100° C. for 1 hour, hot rolled at a final rolling temperature of 800° C. and wound into a coil at a temperature of 610° C. to obtain a hot rolled sheet of 1.8 mm in thickness. Thereafter, the hot rolled sheet is subjected to a hot band annealing at 1000° C. in an atmosphere of 100 vol % N2 for 30 seconds and cold rolled to obtain a cold rolled sheet having a sheet thickness of 0.35 mm, which is subjected to a final annealing at 980° C. in an atmosphere of 20 vol % H2-80 vol % N2 for 15 seconds to form a cold rolled and annealed sheet.

From the thus cold rolled and annealed sheet are cut out Epstein samples with a width: 30 mm×a length: 280 mm in the rolling direction and in a direction perpendicular to the rolling direction to measure an iron loss W10/400 and a magnetic flux density B50 according to JIS C2550, respectively. These results are shown in Table 1.

TABLE 1 Chemical composition (mass %) No C Si Mn P S Al N Bi Ca Mg Sb  1 0.0015 3.20 1.59 0.011 0.0003 1.20 0.0020 0.0002 tr. tr. tr.  2 0.0012 3.12 1.59 0.011 0.0004 1.20 0.0015 0.0011 tr. tr. tr.  3 0.0013 3.13 1.57 0.011 0.0003 1.16 0.0016 0.0020 tr. tr. tr.  4 0.0015 3.14 1.56 0.011 0.0002 1.16 0.0016 0.0027 tr. tr. tr.  5 0.0017 3.21 1.60 0.012 0.0003 1.15 0.0014 0.0037 tr. tr. tr.  6 0.0017 3.15 1.59 0.013 0.0004 1.18 0.0015 0.0045 tr. tr. tr.  7 0.0016 3.16 0.15 0.012 0.0003 1.17 0.0014 0.0002 tr. tr. tr.  8 0.0000 3.14 0.91 0.011 0.0003 1.16 0.0015 0.0001 tr. tr. tr.  9 0.0019 3.16 1.55 0.012 0.0004 1.16 0.0013 0.0003 tr. tr. tr. 10 0.0022 3.22 2.51 0.013 0.0003 1.15 0.0014 0.0002 tr. tr. tr. 11 0.0016 3.16 3.49 0.012 0.0003 1.18 0.0017 0.0003 tr. tr. tr. 12 0.0014 3.15 4.43 0.014 0.0004 1.18 0.0016 0.0004 tr. tr. tr. 13 0.0014 3.16 5.20 0.010 0.0004 1.17 0.0023 0.0003 tr. tr. tr. 14 0.0014 3.14 0.50 0.013 0.0005 1.20 0.0019 0.0025 tr. tr. tr. 15 0.0013 3.15 1.53 0.012 0.0003 1.17 0.0017 0.0005 tr. tr. tr. 16 0.0017 3.17 1.52 0.013 0.0003 1.18 0.0019 0.0003 tr. tr. 0.0053 17 0.0011 3.16 1.57 0.011 0.0004 1.20 0.0018 0.0003 tr. tr. 0.0174 18 0.0014 3.14 1.56 0.012 0.0003 1.20 0.0016 0.0005 tr. tr. tr. 19 0.0016 3.20 1.56 0.012 0.0004 1.16 0.0021 0.0004 tr. tr. tr. 20 0.0018 3.14 1.56 0.014 0.0004 1.21 0.0019 0.0003 tr. tr. tr. 21 0.0021 3.12 1.57 0.013 0.0003 1.20 0.0017 0.0005 0.0023 tr. tr. 22 0.0020 3.17 1.55 0.012 0.0004 1.21 0.0016 0.0015 0.0035 tr. tr. 23 0.0021 3.13 1.56 0.012 0.0005 1.20 0.0017 0.0015 0.0047 tr. tr. 24 0.0016 3.14 1.54 0.013 0.0003 1.22 0.0018 0.0016 0.0060 tr. tr. 25 0.0017 3.13 1.54 0.011 0.0003 1.21 0.0016 0.0035 0.0032 tr. tr. 26 0.0015 3.18 1.53 0.012 0.0004 1.23 0.0015 0.0005 tr. 0.0014 tr. 27 0.0016 3.19 1.54 0.011 0.0004 1.24 0.0021 0.0015 tr. 0.0015 tr. 28 0.0014 3.22 1.57 0.012 0.0003 1.22 0.0020 0.0015 tr. 0.0041 tr. 29 0.0013 0.88 1.52 0.030 0.0004 2.60 0.0025 0.0003 tr. tr. tr. 30 0.0015 3.14 1.53 0.012 0.0003 1.22 0.0017 0.0002 tr. tr. tr. 31 0.0017 3.16 1.54 0.012 0.0003 1.23 0.0016 0.0003 tr. tr. tr. 32 0.0016 3.18 1.56 0.012 0.0004 1.20 0.0017 0.0002 tr. tr. tr. 33 0.0014 2.22 1.26 0.012 0.0003 2.18 0.0021 0.0005 tr. tr. tr. 34 0.0016 3.55 1.20 0.004 0.0004 1.14 0.0021 0.0003 tr. tr. tr. 35 0.0017 4.92 1.13 0.004 0.0003 0.32 0.0016 0.0003 tr. tr. tr. 36 0.0015 2.79 1.58 0.013 0.0003 1.33 0.0017 0.0005 tr. tr. tr. 37 0.0014 2.49 1.57 0.011 0.0004 2.44 0.0021 0.0005 tr. tr. tr. 38 0.0018 1.52 1.58 0.012 0.0004 3.47 0.0022 0.0002 tr. tr. tr. 39 0.0013 2.79 1.56 0.013 0.0017 1.32 0.0014 0.0003 tr. tr. tr. 40 0.0015 2.79 1.57 0.011 0.0055 1.32 0.0016 0.0002 tr. tr. tr. 41 0.0016 2.78 1.58 0.014 0.0004 1.33 0.0015 0.0003 tr. tr. tr. 42 0.0017 2.79 1.56 0.013 0.0003 1.32 0.0060 0.0005 tr. tr. tr. 43 0.0059 2.79 1.57 0.012 0.0005 1.32 0.0010 0.0002 tr. tr. tr. Magnetic properties Magnetic Chemical composition Sheet Iron loss flux (mass %) thickness W10/400 density No Sn Mo Ti (mm) (W/kg) B50 (T) Remarks  1 tr. 0.0013 0.0002 0.35 15.20 1.67 Invention Steel  2 tr. 0.0008 0.0001 0.35 15.21 1.67 Invention Steel  3 tr. 0.0014 0.0002 0.35 15.28 1.67 Invention Steel  4 tr. 0.0015 0.0001 0.35 15.30 1.67 Invention Steel  5 tr. 0.0010 0.0002 0.35 15.76 1.68 Comparative Steel  6 tr. 0.0011 0.0002 0.35 16.11 1.68 Comparative Steel  7 tr. 0.0011 0.0003 0.35 16.00 1.69 Comparative Steel  8 tr. 0.0014 0.0002 0.35 15.70 1.68 Comparative Steel  9 tr. 0.0012 0.0001 0.35 15.30 1.68 Invention Steel 10 tr. 0.0010 0.0002 0.35 15.10 1.66 Invention Steel 11 tr. 0.0014 0.0002 0.35 15.04 1.65 Invention Steel 12 tr. 0.0013 0.0002 0.35 15.00 1.65 Invention Steel 13 tr. 0.0013 0.0002 0.35 15.02 1.61 Comparative Steel 14 tr. 0.0009 0.0003 0.35 16.45 1.66 Comparative Steel 15 tr. 0.0008 0.0001 0.35 15.30 1.67 Invention Steel 16 tr. 0.0014 0.0001 0.35 15..22 1.68 Invention Steel 17 tr. 0.0012 0.0002 0.35 15.17 1.69 Invention Steel 18 0.0070 0.0010 0.0002 0.35 15.14 1.68 Invention Steel 19 0.0240 0.0008 0.0003 0.35 15.12 1.69 Invention Steel 20 0.0420 0.0007 0.0001 0.35 15.09 1.69 Invention Steel 21 tr. 0.0014 0.0001 0.35 14.98 1.67 Invention Steel 22 tr. 0.0013 0.0003 0.35 15.07 1.67 Invention Steel 23 tr. 0.0008 0.0002 0.35 15.20 1.67 Invention Steel 24 tr. 0.0008 0.0002 0.35 15.70 1.67 Comparative Steel 25 tr. 0.0015 0.0003 0.35 15.59 1.67 Comparative Steel 26 tr. 0.0016 0.0002 0.35 14.98 1.67 Invention Steel 27 tr. 0.0017 0.0002 0.35 15.08 1.67 Invention Steel 28 tr. 0.0015 0.0001 0.35 15.07 1.67 Invention Steel 29 tr. 0.0013 0.0002 0.35 18.42 1.67 Comparative Steel 30 tr. 0.0001 0.0002 0.35 15.40 1.67 Invention Steel 31 tr. 0.0022 0.0002 0.35 15.36 1.68 Invention Steel 32 tr. 0.0028 0.0001 0.35 15.42 1.68 Invention Steel 33 tr. 0.0011 0.0003 0.35 15.23 1.67 Invention Steel 34 tr. 0.0012 0.0002 0.35 14.70 1.67 Invention Steel 35 tr. 0.0014 0.0002 0.35 14.62 1.60 Comparative Steel 36 tr. 0.0013 0.0002 0.35 14.96 1.67 Invention Steel 37 tr. 0.0014 0.0001 0.35 14.78 1.66 Invention Steel 38 tr. 0.0013 0.0002 0.35 15.03 1.63 Comparative Steel 39 tr. 0.0013 0.0001 0.35 15.22 1.65 Invention Steel 40 tr. 0.0013 0.0003 0.35 17.53 1.65 Comparative Steel 41 tr. 0.0013 0.0037 0.35 16.28 1.65 Comparative Steel 42 tr. 0.0014 0.0003 0.35 16.41 1.65 Comparative Steel 43 tr. 0.0011 0.0003 0.35 16.45 1.65 Comparative Steel

As seen from Table 1, the steel sheets satisfying our chemical composition, particularly the steel sheets decreasing Bi content are excellent in the high-frequency iron loss property irrespective of a high Mn content.

Claims

1-5. (canceled)

6. A non-oriented electrical steel sheet having a chemical composition comprising C: not more than 0.005 mass %, Si: 1.5-4 mass %, Mn: 1.0-5 mass %, P: not more than 0.1 mass %, S: not more than 0.005 mass %, Al: not more than 3 mass %, N: not more than 0.005 mass %, Bi: not more than 0.0030 mass % and the remainder being Fe and inevitable impurities.

7. The non-oriented electrical steel sheet according to claim 6, further containing one or two of Ca: 0.0005-0.005 mass % and Mg: 0.0002-0.005 mass % in addition to the above chemical composition.

8. The non-oriented electrical steel sheet according to claim 6, further containing one or two of Sb: 0.0005-0.05 mass % and Sn: 0.0005-0.05 mass % in addition to the above chemical composition.

9. The non-oriented electrical steel sheet according to claim 6, further containing Mo: 0.0005-0.0030 mass % in addition to the above chemical composition.

10. The non-oriented electrical steel sheet according to claim 6, further containing Ti: not more than 0.002 mass %.

11. The non-oriented electrical steel sheet according to claim 7, further containing one or two of Sb: 0.0005-0.05 mass % and Sn: 0.0005-0.05 mass % in addition to the above chemical composition.

12. The non-oriented electrical steel sheet according to claim 7, further containing Mo: 0.0005-0.0030 mass % in addition to the above chemical composition.

13. The non-oriented electrical steel sheet according to claim 8, further containing Mo: 0.0005-0.0030 mass % in addition to the above chemical composition.

14. The non-oriented electrical steel sheet according to claim 11, further containing Mo: 0.0005-0.0030 mass % in addition to the above chemical composition.

15. The non-oriented electrical steel sheet according to claim 7, further containing Ti: not more than 0.002 mass %.

16. The non-oriented electrical steel sheet according to claim 8, further containing Ti: not more than 0.002 mass %.

17. The non-oriented electrical steel sheet according to claim 11, further containing Ti: not more than 0.002 mass %.

18. The non-oriented electrical steel sheet according to claim 9, further containing Ti: not more than 0.002 mass %.

19. The non-oriented electrical steel sheet according to claim 12, further containing Ti: not more than 0.002 mass %.

20. The non-oriented electrical steel sheet according to claim 13, further containing Ti: not more than 0.002 mass %.

21. The non-oriented electrical steel sheet according to claim 14, further containing Ti: not more than 0.002 mass %.

Patent History
Publication number: 20160076125
Type: Application
Filed: Mar 12, 2014
Publication Date: Mar 17, 2016
Inventors: Shinji Koseki (Tokyo), Yoshihiko Oda (Tokyo), Hiroaki Toda (Tokyo), Tatsuhiko Hiratani (Tokyo), Tadashi Nakanishi (Tokyo)
Application Number: 14/767,735
Classifications
International Classification: C22C 38/60 (20060101); C22C 38/12 (20060101); C22C 38/00 (20060101); C22C 38/04 (20060101); C22C 38/02 (20060101); C22C 38/14 (20060101); C22C 38/06 (20060101);