JP2001181806A - Nonriented silicon steel sheet excellent in magnetic permeability, hot rolled sheet thereof and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonriented silicon steel sheet high in magnetic permeability and to provided a method for producing the same. SOLUTION: This nonoriented silicon steel sheet excellent in magnetic permeability contains, in steel, by weight, 0.1 to 1.0% Si, 0.1 to 0.8% Mn and 0.1 to 1.0% Al, and the balance Fe with inevitable impurities, has αγ transformation and has electrical resistivity of 10×10-8 Ωm to 32×10-8 Ωm and magnetic permeability μ 15/60 of 1,500 (Gauss/Oe) or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-oriented electrical steel sheet having high magnetic permeability and excellent magnetic properties, a hot-rolled steel sheet for a non-oriented electrical steel sheet, and its manufacture, which is used as an iron core material of electric equipment. It is about the method.

[0002]

2. Description of the Related Art In recent years, in the fields of electric machines, especially rotating machines and medium-sized and small-sized transformers in which non-oriented electrical steel sheets are used as iron core materials, worldwide electric power and energy savings, as well as chlorofluorocarbon gas regulations. Among the movements for global environmental conservation, such as the above, the movement for higher efficiency is rapidly spreading. For this reason, there is an increasing demand for non-oriented electrical steel sheets to have improved properties, that is, a high permeability non-oriented electrical steel sheet.

Conventionally, in non-oriented electrical steel sheets, as a means of reducing iron loss, a method of increasing the content of Si or Al or the like has been generally adopted from the viewpoint of reducing eddy current loss due to an increase in electric resistance. However, in this method, on the other hand, there is a problem that a decrease in magnetic permeability cannot be avoided. In order to overcome such problems, a method of improving both the magnetic permeability and the iron loss by increasing the crystal grain size of the hot-rolled sheet has been performed.

[0004] In a non-oriented electrical steel sheet having a transformation, the crystal grain size before cold rolling is secured by terminating hot rolling in the vicinity of the upper limit of the α region, thereby improving the magnetic permeability of the product. Things have been done. From this point of view, JP-A-56-38420 discloses that the hot-rolling end temperature is A
How to reduce the coarsening of the hot rolled crystal structure are disclosed by the intermediate temperature of r ₃ points and Ar ₁ point or less winding at 680 ° C. or higher. However, there is a limit in improving the magnetic permeability of the non-oriented electrical steel sheet only by controlling the hot rolling conditions.

A method for improving the magnetic permeability of a non-oriented electrical steel sheet by improving the primary recrystallization texture is disclosed in
Addition of Sn described in JP-A-55-158252;
A method for producing a non-oriented electrical steel sheet having excellent magnetic properties by improving the texture by adding Sn or Cu described in JP-A-180014 or by adding Sb described in JP-A-59-100217 is disclosed. Although disclosed, the cost for adding Sn, Cu, Sb, etc., which are texture control elements, is by no means low, and the provision of a low-cost method for producing a non-oriented electrical steel sheet was limited. .

[0006] In addition, measures in the manufacturing process such as devising a finish annealing cycle as described in Japanese Patent Application Laid-Open No. 57-35626 have been made. There was no significant improvement in permeability. The present inventors, in order to overcome this limitation, performed a detailed analysis, using a low-alloy component system, performing controlled hot rolling, and controlling the electrical resistivity of the steel within a certain range. Thus, the present inventors have found a new finding that a non-oriented electrical steel sheet excellent in both magnetic permeability and iron loss can be manufactured.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to solve such problems in the prior art and to provide a non-oriented electrical steel sheet having excellent magnetic permeability and a method for producing the same. .

[0008]

The gist of the present invention is as follows. (1) By mass% in steel, 0.1% ≦ Si ≦ 1.0%, 0.1%
1% ≦ Mn ≦ 0.8%, 0.1% ≦ Al ≦ 1.0%, the balance being Fe and unavoidable impurities, having αγ transformation, and electric resistivity of 10 × 10 ⁻⁸ Ωm 32x1 or more
0 ⁻⁸ Ωm or less, and the magnetic permeability μ15 / 60 is 1500 (Gauss
s / Oe) or more, a non-oriented electrical steel sheet having excellent magnetic permeability.

(2) By mass% in steel, 0.1% ≦ Si ≦
1.0%, 0.1% ≦ Mn ≦ 0.8%, 0.1% ≦ Al
≦ 1.0%, the balance being Fe and unavoidable impurities, having αγ transformation, and having an electric resistivity of 10 × 10 ⁻⁸ Ω.
m to 32 × 10 ⁻⁸ Ωm, the grain size of the recrystallized structure in the cross section of the hot-rolled sheet is 5 μm to less than 50 μm, and the area ratio of the processed structure in the cross section of the hot-rolled sheet is 0.01%.
A hot-rolled sheet for non-oriented electrical steel sheets having excellent magnetic permeability, which is not less than 80%.

(3) By mass% in steel, 0.1% ≦ Si ≦
1.0%, 0.1% ≦ Mn ≦ 0.8%, 0.1% ≦ Al
≦ 1.0%, the balance being Fe and unavoidable impurities, having αγ transformation, and having an electric resistivity of 10 × 10 ⁻⁸ Ω.
m or 32 × 10 ^-8 Ωm or less annealing the hot rolled sheet at a temperature of ₁ point Ac, for non-oriented electrical steel sheet excellent in magnetic permeability, characterized in that the crystal grain size was 50μm or 500μm or less Hot rolled sheet.

(4) By mass% in steel, 0.1% ≦ Si ≦
1.0%, 0.1% ≦ Mn ≦ 0.8%, 0.1% ≦ Al
≦ 1.0%, the balance being Fe and unavoidable impurities, having αγ transformation, and having an electric resistivity of 10 × 10 ⁻⁸ Ω.
m to 32 × 10 ⁻⁸ Ωm or less for a non-oriented electrical steel sheet having excellent magnetic permeability, wherein the parameter G determined by the conditions of the final pass in the finish hot rolling satisfies the range of the following equation. Manufacturing method of hot rolled sheet.

(Equation 2)

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The present inventors have repeatedly studied the problems in the prior art in order to simultaneously achieve low iron loss and high magnetic flux density,
In a non-oriented electrical steel sheet having a transformation, Si: 0.1
% -1.0%, Al: 0.1% -1.0%, Mn: 0.
A steel containing 1% to 0.8% is designed with a component having an αγ transformation, and is subjected to controlled hot rolling under specific conditions to form a characteristic hot rolled structure. By using a rolled sheet as a starting material, it has been found that a non-oriented electrical steel sheet excellent in both magnetic permeability and iron loss can be manufactured.

Hitherto, in order to improve the magnetic permeability of a non-oriented electrical steel sheet, the crystal structure before cold rolling has been coarsened. However, according to the present invention, although the permeability can be further improved by coarsening the crystal structure before cold rolling by hot-rolled sheet annealing, hot-rolled sheet annealing was performed even if hot-rolled sheet annealing was omitted. It has been found that it is possible to obtain a magnetic permeability comparable to that of the material.

First, the components will be described. Si is added to increase the specific resistance of the steel sheet, reduce the eddy current loss, and improve the iron loss value. If the Si content is less than 0.1%, sufficient resistivity cannot be obtained, so it is necessary to add 0.1% or more. On the other hand, if the Si content exceeds 1.0%, the magnetic permeability decreases, so the content is set to 1.0% or less. Mn
Has the effect of increasing the specific resistance of the steel sheet and reducing the eddy current loss as in the case of Si. For this reason, the Mn content is 0.1.
It must be 10% or more. On the other hand, when the Mn content is 0.1.
If it exceeds 8%, the magnetic permeability is reduced.

Al has the effect of increasing the specific resistance of the steel sheet and reducing the eddy current loss similarly to Si, and therefore, it is preferable to add 0.1% or more, especially when low iron loss is desired. To increase magnetic permeability and increase electrical resistivity, Al
The content is preferably 0.6% or more. Also, A
If the l content exceeds 1.0%, the magnetic permeability decreases.
It is necessary to be 1.0% or less.

If the electrical resistivity of the steel is less than 10 × 10 ⁻⁸ Ωm, the iron loss deteriorates, so it is set to 10 × 10 ⁻⁸ Ωm or more. On the other hand, if it exceeds 32 × 10 ⁻⁸ Ωm, the magnetic permeability decreases. Therefore, it is set to 32 × 10 ⁻⁸ Ωm or less. In addition, P, B, Ni, Sn, Cu, and S are used to improve the mechanical properties, magnetic properties, and rust resistance of the product, or for other purposes.
The effect of the present invention is not impaired even if one or more kinds of b are contained in steel.

It is necessary to control the C content to 0.004% or less. If the C content exceeds 0.004%, not only magnetic aging occurs during the use of the product, iron loss is deteriorated, but also impurity elements and carbides are generated to inhibit crystal grain growth during finish annealing, As a result, iron loss deteriorates, so it is necessary to set the content to 0.004% or less. S and N partially re-dissolve during slab heating in the hot rolling step, and form sulfides such as MnS and nitrides such as AlN during hot rolling. Because these hinder grain growth during recrystallization annealing,
It is preferable that both of the contents be 0.003% or less.

P is added in a range of up to 0.1% in order to improve the punchability of the product. P ≦
If it is 0.2%, there is no problem from the viewpoint of the magnetic properties of the product. Next, the process conditions of the present invention will be described. Since hot rolling of steel in the present invention has an αγ transformation, when the hot rolling finishing temperature exceeds (Ar ₃ + Ar ₁ ) / 2, the hot deformation resistance tends to fluctuate during rolling, and the sheet thickness accuracy is reduced. An excellent hot rolled steel sheet cannot be obtained. For this reason, the hot rolling finishing temperature is set to (Ar ₃ + Ar ₁ ) / 2 or less. If the hot rolling finish temperature exceeds 1050 ° C.,
Since winding at 0 ° C or less becomes difficult, the temperature is set to 1050 ° C or less. Further, if the hot rolling finish temperature is lower than 850 ° C., the hot deformation resistance increases and rolling becomes difficult.

A steel slab comprising the above components is produced by melting in a converter and manufactured by continuous casting or ingot-bulking rolling. The steel slab is heated by a known method. This slab is subjected to hot rolling to a predetermined thickness. In the present invention, the characterization of the crystal structure is all performed on a plate thickness section parallel to the rolling direction. In the present invention, in order to obtain a high magnetic permeability of 1500 Gauss / Oe or more by a single cold rolling and annealing without performing hot-rolled sheet annealing, hot rolling is performed while satisfying specific conditions in the final pass of finish hot rolling. There is a need. The condition is that the G parameter defined by the equation (2) is 1.38 or more.
17 or less.

(Equation 3) When the G parameter is less than 1.38, the area ratio of the processed structure in the cross section of the hot-rolled sheet is less than 0.01%, and a high magnetic permeability of 1500 Gauss / Oe or more cannot be obtained in the product. Needs to be On the other hand, G
If the parameter is more than 5.17, the area ratio of the processed structure in the cross section of the hot-rolled sheet becomes more than 80%, and ridging occurs in the product after cold rolling, and the space factor at the time of lamination is significantly deteriorated. , 5.17 or less. In addition,
The true distortion of the last pass is calculated by Expression (3), and the average distortion speed is calculated by Expression (4).

(Equation 4) The average crystal grain size of the recrystallized structure in the cross section of the hot-rolled sheet is 5μ.
It is necessary that the area ratio of the processed structure in the section in the rolling direction of the steel sheet is 0.01% or more and 80% or less. When the crystal grain size of the hot-rolled sheet is less than 5 μm,
Since the high magnetic permeability intended by the present invention cannot be obtained, the grain size of the recrystallized grains of the hot-rolled sheet is set to 5 μm or more. Also, 50μm
In the case of exceeding, a high magnetic permeability cannot be obtained in a state coexisting with the processed structure.

If the area ratio of the processed structure exceeds 80%, ridging occurs after rolling and the surface properties of the product deteriorate.
0% or less. If the area ratio of the worked structure is less than 0.01%, a single cold rolling and annealing cannot provide a high magnetic permeability of 1500 Gauss / Oe or more, so that 0.01% or more is necessary. In the hot-rolled sheet of the component of the present invention, it is easier to obtain high magnetic permeability when the processed structure remains. By using this hot-rolled sheet, μ15 / 60 is reduced to 150 by one cold rolling and annealing.
It is possible to obtain an excellent magnetic permeability of 0 Gauss / Oe or more.

The term "worked structure" as used herein refers to both a portion where transitions are present in the structure at a high density and become dark by etching, and a stretched grain obtained by rolling. Further, the recrystallized structure referred to in the present invention refers to a structure composed of equiaxed grains. The hot rolled sheet may be subjected to hot rolled sheet annealing in order to coarsen the crystal structure before cold rolling. In this case, the crystal grain size of the hot-rolled steel sheet needs to be 50 μm or more and 500 μm or less. If the hot-rolled crystal structure after the hot-rolled sheet annealing is less than 50 μm, the effect of hot-rolled sheet annealing is not seen, so
It is necessary to do above. On the other hand, if the hot-rolled crystal structure is 500 μm or more after hot-rolled sheet annealing, the surface properties of the steel sheet after cold rolling are deteriorated.

The hot-rolled sheet annealing is preferably performed at a temperature of not more than _one point Ac in order to prevent the crystal grains from being refined by transformation. The magnetic permeability μ15 / 60 used in the present invention refers to a magnetic flux density at an excitation magnetic flux density of 1.5 Tesla and a frequency of 60 Hz.
Gauss, the exciting magnetic field strength is measured in units of Oe, and a value obtained by dividing the magnetic flux density by the exciting magnetic field strength is used.

[0023]

Next, an embodiment of the present invention will be described. <Example 1> A slab for non-oriented electromagnetic steel having the components shown in Table 1 was heated by a usual method, and was heated to 2.5 m by hot rolling.
m. Next, this was cold-rolled to 0.5 mm
Finished to a thickness and annealed at 730 ° C. for 30 seconds in a continuous annealing furnace. Thereafter, the sample was cut into Epstein samples, and the magnetic properties were measured. Table 1 also shows the components of the present invention and the comparative examples and the results of the magnetic permeability measurement.

As described above, when the steel component is within the range of the present invention, it is possible to obtain a non-oriented electrical steel sheet having high magnetic permeability and excellent magnetic properties.

[0025]

[Table 1] <Example 2> A slab for non-oriented electromagnetic steel having the components shown in Table 2 was heated by a usual method, and was finished to 2.5 mm by hot rolling.

Thereafter, it was subjected to pickling and finished to 0.50 mm by cold rolling using a dull roll. Annealing was performed at 730 ° C. for 30 seconds in a continuous annealing furnace. Thereafter, an Epstein test piece was cut out and annealed at 750 ° C. for 2 hours corresponding to a customer, and magnetic properties were measured. Table 3 also shows the area ratio of the processed structure in the hot-rolled crystal structures of the present invention and the comparative example, the particle size of the hot-rolled recrystallized structure, and the results of the magnetic measurement. The comparative example is not suitable because ridging occurs and the surface properties are significantly deteriorated.

[0027]

[Table 2]

[0028]

[Table 3] As described above, by using a hot-rolled sheet having a processed structure equal to or more than a certain value, a material having a high magnetic permeability can be manufactured. <Example 3> A slab for non-oriented electromagnetic steel having the components shown in Table 2 was heated by a usual method and finished to 2.5 mm by hot rolling.

Thereafter, the resultant was pickled and cold rolled using a bright roll to a finish of 0.50 mm. Annealing was performed at 730 ° C. for 30 seconds in a continuous annealing furnace. Thereafter, an Epstein test piece was cut out and annealed at 750 ° C. for 2 hours corresponding to a customer, and magnetic properties were measured. Table 4 also shows the area ratio of the processed structure in the hot-rolled crystal structures of the present invention and the comparative example, the particle size of the hot-rolled recrystallized structure, and the results of the magnetic measurement. Although the comparative example has a high magnetic permeability, ridging occurs and the surface properties are remarkably deteriorated, so that it is not suitable.

[0030]

[Table 4] As described above, by using a hot-rolled sheet having a processed structure equal to or more than a certain value, a material having a high magnetic permeability can be manufactured. <Example 4> A slab for non-oriented electromagnetic steel having the components shown in Table 5 was heated by a usual method, and was finished to 2.3 mm by hot rolling. The hot-rolled sheet was annealed at 950 ° C. below the Ac1 point and the annealing time was varied to change the grain size before cold rolling.

Thereafter, the resultant was pickled and cold rolled with a bright roll to a finish of 0.50 mm. Among these, the full process material was annealed at 730 ° C. for 30 seconds in a continuous annealing furnace. Thereafter, annealing was performed at 750 ° C. for 2 hours corresponding to a customer. The semi-processed material was annealed at 700 ° C. for 20 seconds in a continuous annealing furnace, and then 0.47 mm by skin pass rolling.
Finished thick, cut out Epstein test piece 750 ℃ 2
The magnetic properties were measured by performing annealing corresponding to a time consumer.

Tables 6 and 7 also show the results of the magnetic measurement and the particle size of the structures before cold rolling of the present invention and the comparative examples described in the examples. The comparative example is unsuitable because the surface properties were significantly deteriorated by rolling.

[0033]

[Table 5]

[0034]

[Table 6]

[0035]

[Table 7] By making the appropriate particle size by hot-rolled sheet annealing in this way,
It is possible to manufacture a non-oriented electrical steel sheet having a high value of magnetic permeability. <Example 5> A slab for non-oriented electromagnetic steel having the components shown in Table 5 was heated by a usual method and finished to 2.3 mm by hot rolling. The hot-rolled sheet was annealed at 950 ° C. below the Ac1 point and the annealing time was varied to change the grain size before cold rolling.

Thereafter, the resultant was pickled and cold rolled with a dull roll to a finish of 0.50 mm. This was annealed at 700 ° C. for 20 seconds in a continuous annealing furnace, finished to a 0.47 mm thickness by skin pass rolling, and Epstein test pieces were cut out from these samples, and subjected to annealing at 750 ° C. for 2 hours corresponding to a customer. The magnetic properties were measured. Table 8 also shows the results of the magnetic measurement and the particle size of the structures before cold rolling of the present invention and the comparative examples described in the examples. The comparative example is unsuitable because the surface properties were significantly deteriorated by rolling.

[0037]

[Table 8] By making the appropriate particle size by hot-rolled sheet annealing in this way,
It is possible to manufacture a non-oriented electrical steel sheet having a high value of magnetic permeability.

[0038]

As described above, according to the present invention, it is possible to manufacture a non-oriented electrical steel sheet having high magnetic permeability and excellent magnetic properties.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinichi Kanao 1-1, Niwahata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka Prefecture (72) Inventor Kazufumi Hanzawa Tobata-ku, Kitakyushu-shi, Fukuoka 1-1 Nippon Steel Corporation Yawata Works (72) Inventor Takeshi Takeshi 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Corporation Technology Development Headquarters (72) Inventor Kenichi Murakami Fukuoka F-term (reference) in Nippon Steel Corporation Yawata Works, Kitakyushu-city, Tobata-ku

Claims (4)

[Claims] 1. The steel contains, by mass%, 0.1% ≦ Si ≦ 1.0%, 0.1% ≦ Mn ≦ 0.8%, 0.1% ≦ Al ≦ 1.0%. And the balance consists of Fe and unavoidable impurities, has αγ transformation, has an electric resistivity of 10 × 10 ⁻⁸ Ωm or more and 32 × 10 ⁻⁸ Ωm or less, and has a magnetic permeability μ15 / 60 of 1500 (Gauss / Oe) or more. A non-oriented electrical steel sheet having excellent magnetic permeability. 2. The steel contains, by mass%, 0.1% ≦ Si ≦ 1.0%, 0.1% ≦ Mn ≦ 0.8%, 0.1% ≦ Al ≦ 1.0%. And the balance consists of Fe and unavoidable impurities, has αγ transformation, and has an electric resistivity of 10 × 10 ⁻⁸ Ωm or more and 32 × 10 ⁻⁸ Ωm or less,
Excellent in magnetic permeability, characterized in that the crystal grain size of the recrystallized structure in the cross section of the hot rolled sheet is 5 μm or more and less than 50 μm, and the area ratio of the processed structure in the cross section of the hot rolled sheet is 0.01% or more and 80% or less. Hot rolled sheet for non-oriented electrical steel sheets. 3. The steel contains, by mass%, 0.1% ≦ Si ≦ 1.0%, 0.1% ≦ Mn ≦ 0.8%, 0.1% ≦ Al ≦ 1.0%. Then, a hot-rolled sheet consisting of the balance of Fe and unavoidable impurities, having αγ transformation, and having an electric resistivity of 10 × 10 ⁻⁸ Ωm or more and 32 × 10 ⁻⁸ Ωm or less is annealed at a temperature of ₁ point or less of Ac, A hot-rolled sheet for non-oriented electrical steel sheets having excellent magnetic permeability, wherein the particle size is not less than 50 μm and not more than 500 μm. 4. The steel contains, by mass%, 0.1% ≦ Si ≦ 1.0%, 0.1% ≦ Mn ≦ 0.8%, 0.1% ≦ Al ≦ 1.0%. A steel consisting of Fe and unavoidable impurities, having an αγ transformation, and having an electric resistivity of 10 × 10 ⁻⁸ Ωm or more and 32 × 10 ⁻⁸ Ωm or less is determined by a final pass condition in hot rolling in a final pass. A method for producing a hot-rolled sheet for non-oriented electrical steel sheets having excellent magnetic permeability, wherein G satisfies the range of the following expression. (Equation 1)