JP2000219916A - Manufacturing method of non-oriented electrical steel sheet with high magnetic flux density and low iron loss - Google Patents

Abstract

(57) [Problem] To provide a method for producing a non-oriented electrical steel sheet having stable and low iron loss. SOLUTION: In weight%, 0.1% ≦ Si ≦ 2.5%, 0.1% ≦ Mn ≦
1.5%, C ≤ 0.004%, N ≤ 0.002%, S ≤ 0.002%, Ti ≤ 0.00
3%, Nb ≦ 0.003%, V ≦ 0.005%, Zr ≦ 0.003%, Ca ≦ 0.003
%, As ≦ 0.003%, Cr ≦ 0.05%, Sn ≦ 0.01%, Cu ≦ 0.05%
, O ≤ 0.02%, the balance consisting of Fe and unavoidable impurities, having a Q value of -4.70 or less and having an αγ transformation, is hot-rolled into a hot-rolled sheet, and then subjected to one cold rolling step. , A method of manufacturing a non-oriented electrical steel sheet which is subjected to finish annealing and then subjected to a skin pass rolling step or not to be applied, wherein the hot-rolling finishing temperature is Ar ₃ points or more. A method for producing non-oriented electrical steel sheets with high density and low iron loss.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a non-oriented electrical steel sheet having excellent magnetic properties with high magnetic flux density and low iron loss, which is used as an iron core material of electric equipment.

[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. Therefore, there is an increasing demand for non-oriented electrical steel sheets to have improved properties, that is, high magnetic flux density and low iron loss. By the way, in the non-oriented electrical steel sheet, conventionally, 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, this method has a problem that the magnetic flux density cannot be reduced. In order to overcome such problems, a method of improving both magnetic flux density and iron loss by increasing the crystal grain size of a hot-rolled sheet has been performed. Conventionally, in a non-oriented electrical steel sheet having a transformation, it is possible to secure the crystal grain size before cold rolling by terminating hot rolling near the upper limit of the α region, and as a result, improve the magnetic flux density and iron loss of the product. Has been done.
From this point of view, JP-A-56-38420 discloses that the hot-rolled crystal structure is coarsened by winding at a temperature of 680 ° C. or more with the hot-rolling finishing temperature being lower than the intermediate temperature between the Ar ₃ point and the Ar ₁ point. Is disclosed. However, the fact that the hot-rolling finishing temperature rises to the γ region is to be avoided because the hot-rolled structure becomes finer due to the progression of transformation to the α-phase after the end of hot-rolling, and as a result the magnetic properties deteriorate. It has been.

On the other hand, in an actual finishing hot rolling mill, it is difficult to eliminate the temperature distribution in the longitudinal direction of the coil because the rolling speed during biting and the rolling speed in a steady rolling state are necessarily different. In order to perform hot rolling at the upper limit of the α region, there is a disadvantage that the set rolling temperature must be lowered. In addition, since the Ar ₁ transformation point of a general low-grade non-oriented electrical steel sheet is around 860 ° C., there is a limit to increasing the hot-rolling finishing temperature to grow the hot-rolled crystal structure, There is a limit to the improvement of the magnetic properties due to the increase of the crystal structure before cold rolling.

As a technique for overcoming the limit of the coarsening of the crystal structure before cold rolling by such controlled hot rolling, Japanese Patent Laid-Open Publication No. Sho 57-35 discloses a technique.
No. 628 discloses that the hot-rolled crystal structure is refined by setting the hot-rolling finishing temperature to ₃ points or more, and then the hot-rolled sheet is annealed at a temperature of ₃ points or less to coarsen the crystal structure before cold rolling. Is disclosed. In addition, a self-annealing method, in which a hot-rolled sheet is wound at a high temperature and then annealed with the heat retained in the coil, is used as a method of suppressing the increase in cost due to the addition of the hot-rolled sheet annealing step and coarsening the crystal structure before cold rolling. It is disclosed in JP-A-54-76422 and JP-A-58-136718.

[0005] However, the addition of a hot-rolled sheet annealing step is not preferable because it causes an increase in production cost, and is not practically carried out in a low-grade non-oriented electrical steel sheet having a transformation. Further, in the self-annealing method, there is a problem in that the magnetic characteristics in the longitudinal direction of the coil vary due to uneven temperature in the coil caused by winding the coil at a high temperature.

On the other hand, in order to reduce iron loss, it is necessary to not only increase the content of Si, Al, etc.
As described in Japanese Patent No. 0169, there is disclosed a method for making precipitates harmless by using high-purity steel by reducing Mn and S. However, pure purification of steel alone cannot overcome the above-mentioned limit of coarsening of the crystal structure before cold rolling by controlled hot rolling, and there is a limit to high magnetic flux density.

As a method for improving the magnetic properties of a non-oriented electrical steel sheet by improving the primary recrystallized texture, Sn is added as disclosed in JP-A-55-158252.
There is disclosed a method for producing a non-oriented electrical steel sheet having excellent magnetic properties by improving the texture by adding Sn and Cu as disclosed in Japanese Patent Application Publication No. 2-180014 or adding Sb as disclosed in Japanese Patent Application Laid-Open No. 59-100217. The cost of adding Sn, Cu or Sb, which is a texture control element, is not low at all, and there is a limit in providing a low-cost method for producing a non-oriented electrical steel sheet. Also, Japanese Patent Application Laid-Open No. 57-35
Although measures have been taken in the manufacturing process, such as devising a finish annealing cycle as described in Japanese Patent No. 626,
In each case, although the iron loss was reduced, the effect on the magnetic flux density was not so significant.

In order to overcome the limitations of the prior art, the inventors of the present invention disclosed in Japanese Patent Application Laid-Open No. Hei 9-125144 to reduce impurity elements and set the hot-rolled finish to a γ-phase region of ₃ points or more of Ar, A method for manufacturing a non-oriented electrical steel sheet having a low cost, a high magnetic flux density and a low iron loss by winding at a low temperature has been disclosed.

[0009] However, even with these techniques, when continuously producing non-oriented electrical steel sheets, even though the individual conditions are satisfied, variations are likely to occur for each charge, resulting in a stable operation. From the viewpoint of obtaining non-oriented electrical steel sheets with low iron loss, some problems remain.

[0010] As described above, according to the prior art, it has not been possible to produce a non-oriented electrical steel sheet having a high magnetic flux density and a low iron loss, and it has not been possible to meet the above demand for a non-oriented electrical steel sheet. The inventors have tried to overcome this limitation
As a result of detailed analysis, a new finding was found that if the product of the total amount of harmful elements and carbon is equal to or less than a certain value, a non-oriented electrical steel sheet with low iron loss can be stably manufactured.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to solve such problems in the prior art and to provide a non-oriented electrical steel sheet having a high magnetic flux density and a low iron loss.

[0012]

The gist of the present invention is as follows. (1) By weight%, 0.1% ≦ Si ≦ 3.5%, 0.1% ≦ Mn ≦ 1.5%, C ≦ 0.004%, N ≦ 0.002%, S ≦ 0.002 %, Ti ≦ 0.003%, Nb ≦ 0.003%, V ≦ 0.005%, Zr ≦ 0.003%, Ca ≦ 0.003%, As ≦ 0.003%, Cr ≦ 0.05% , Sn ≦ 0.01%, Cu ≦ 0.05%, O ≦ 0.02%, the balance being Fe and unavoidable impurities,
A slab having a α-γ transformation with a Q value determined by the formula (1) of -4.70 or less is hot-rolled into a hot-rolled sheet, then subjected to one cold rolling step, and then subjected to finish annealing, and thereafter A method for producing a non-oriented electrical steel sheet which is subjected to a skin pass rolling step or not, wherein a hot-rolling finishing temperature is set to ₃ points or more, wherein the magnetic flux density is high and the iron loss is low. Steel sheet manufacturing method. Q = log [([Ti%] + [Nb%] + [V%] + [Zr%] + [Ca%]) × [C%]] Equation (1) where [Ti%], [Nb%], [V%], [Zr%], [C%], [Ca%]
(2) The weight concentration of Ti, Nb, V, Zr, Ca, and C in a product, respectively. (2) The slab further contains 0.1% ≦ Al ≦ 2% by weight. 1) A method for producing a non-oriented electrical steel sheet having a high magnetic flux density and a low iron loss as described above. (3) The production of a non-oriented electrical steel sheet having a high magnetic flux density and a low iron loss according to the above (1) or (2), wherein the hot-rolled sheet after the finish hot-rolling is wound at a temperature of 680 ° C. or more. Law.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The present inventors have conducted intensive studies on the problems in the prior art in order to simultaneously achieve a low iron loss and a high magnetic flux density, and as a result, in a non-oriented electrical steel sheet having a transformation, 0.1% to 3.5%, and 0.1% Al
% To 2% and Mn of 0.1% to 1.5%, the content of C, S, N, Cr, Sn, Cu, O is reduced, and further, Ti, V, Nb, Ca, Zr, reduced while satisfying the As content specific relationship, as well as high purity steel of, reducing the C content at the same time, which the finishing hot-rolled end with Ar ₃ point or more temperature Full-process non-oriented electrical steel sheet that is annealed at the final thickness by one cold rolling by winding at high temperature, or non-oriented to the final thickness by two or more cold rollings with intermediate annealing The present inventors have found that it is possible to produce a non-oriented electrical steel sheet having a high magnetic flux density and a low iron loss in a method for producing a magnetic electrical steel sheet.

The magnetic properties of the non-oriented electrical steel sheet can be improved by enlarging the crystal structure before cold rolling. For this reason, conventionally, in hot-rolling finishing, the hot-rolling finishing temperature has been increased to increase the size of the hot-rolled structure, increase the magnetic flux density of the product, and reduce iron loss. However, when the hot rolling finish temperature is increased to reach the α + γ2 phase region or the γ region, the transformation from the γ phase to the α phase proceeds after the end of the hot rolling, so that the hot rolled structure becomes finer and the magnetic properties deteriorate as a result. To be avoided. Therefore, αγ
It has been considered that it is essential to perform hot rolling at the upper limit of the α range for non-oriented electrical steel sheets having a transformation, but for low-grade non-oriented electrical steel sheets having a low Si content, the Ar ₁ transformation point Is 900 ° C. or less, there is a limit to the coarsening of the hot-rolled crystal structure due to an increase in the hot-rolling finishing temperature, and as a result, there is a limit to the improvement of the magnetic properties.

The present inventors have conducted intensive studies to overcome the limitations of the conventional hot-rolled non-oriented electrical steel sheet having such a transformation. 0.1% to 3.5%, Al 0.1% to 2%
%, Mn containing 0.1% to 1.5% and having αγ transformation, C, S, N, Cr, Cu, Sn, O content is reduced, and further, Ti, V, Nb , Ca, Zr, As
If the steel is made of high purity by simultaneously reducing the content while satisfying the specific formula, the crystal structure of the α phase after transformation will not be refined even if the hot rolling finish temperature is raised to the γ range, and the hot rolled finish As the temperature rises, the hot-rolled crystal structure becomes coarser, and the present inventors have solved the problem of the technology disclosed in Japanese Patent Application Laid-Open No. 9-125144. It has become possible to obtain non-oriented electrical steel sheets with low iron loss.

By using the hot-rolled sheet obtained by such a method as a starting material, a non-oriented electrical steel sheet having a high magnetic flux density and a good iron loss (low iron loss value) in a product after finish annealing. Was successfully manufactured at low cost.

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 3.5%, cold rolling becomes difficult, so the content is set to 3.5% or less.

Mn, like Si, has the effect of increasing the specific resistance of the steel sheet and reducing eddy current loss. For this reason,
The Mn content needs to be 0.1% or more. On the other hand, M
If the n content exceeds 1.5%, the deformation resistance during hot rolling increases and hot rolling becomes difficult, and the crystal structure before cold rolling tends to be finer, which deteriorates the magnetic properties of the product. Needs to be 1.5% or less.

Although there is no problem even if Al in the steel is at the impurity level, Al has the effect of increasing the specific resistance of the steel sheet and reducing the eddy current loss as in the case of Si. If desired, it is preferable to add 0.1% or more and 2% or less. If a large amount of Al is added, the magnetic flux density decreases and the cost increases, so the content is set to 2% or less.

In order to improve the mechanical properties, magnetic properties, and rust resistance of the product or for other purposes, P,
Even if one or more of B, Ni and Sb are contained in steel, the effect of the present invention is not impaired.

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 the slab heating in the hot rolling step, and sulfides such as MnS and A
A nitride such as 1N is formed. The presence thereof provides the nucleus of the α phase during transformation from the γ phase to the α phase after hot rolling and hinders the grain growth of the α phase crystal structure after the transformation. It is necessary to

The Ti content, V content, Nb content, Zr content, Ca content and Cr content are 0.003%, 0.005%, 0.003% and 0.003%, respectively.
If it exceeds 3%, 0.003% or 0.05%, Ti, V,
Precipitation of carbides of Nb, Zr, Ca, Cr becomes remarkable,
The coarsening of the hot-rolled crystal structure is hindered, and the crystal grain growth in the finish annealing step is hindered, deteriorating the magnetic properties. Therefore, the Ti content, V content, Nb content, Zr content, Ca content, and Cr content are 0.003% or less, 0.005% or less, 0.003% or less, and 0.003% or less, respectively.
%, 0.003%, and 0.05% or less.

In the present invention, each of Ti, V, Nb,
In addition to the content of Zr and Ca alone, a specific relationship needs to be established between the total amount including the entirety and the C content. That is, at the Q value determined by the equation (1), Q = log [([Ti%] + [Nb%] + [V%] + [Zr%] + [Ca%]) × [C%]] Equation (1) where [Ti%], [Nb%], [V%], [Zr%], [C%], [Ca%]
Is a weight concentration in a product of Ti, Nb, V, Zr, Ca, and C respectively. When the Q value of the formula (1) exceeds -4.70, a low iron loss non-oriented electrical steel sheet intended by the present invention is obtained. I can't do that. Therefore, the Q value in equation (1) needs to be -4.70 or less.

Further, as a factor affecting the formation of precipitates that hinder crystal grain growth, it is necessary to suppress the As content. As itself does not form the above-mentioned precipitates such as sulfides and nitrides in steel within the composition range of the present invention. However, if a certain amount or more of As is contained in the steel, the sulfide size becomes fine, so that the coarsening of the hot-rolled crystal structure is significantly inhibited. From such a viewpoint, A
The s content needs to be 0.003% or less.

Since Sn and Cu segregate at the crystal grain boundaries of the steel to hinder grain growth and worsen the iron loss of the product, their contents must be 0.01% or less and 0.05% or less, respectively.

If the O content exceeds 0.02%, Si
Precipitation of oxide inclusions such as O ₂ and Al ₂ O ₃ becomes remarkable. The content needs to be 0.02% or less because it hinders crystal grain growth and worsens the iron loss of the product.

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.

B forms AlN by forming BN during hot rolling.
Is added to prevent fine precipitation of N and render N harmless. The B content needs to be balanced with the amount of N, and the content is preferably such that the ratio B% / N% of both satisfies the range of 0.5 to 1.5.

Ni and Sb have the effect of improving the primary recrystallization texture of the product and, in particular, improving the magnetic flux density. When added for this purpose, Ni preferably satisfies the range of 0.2 to 2.5%, and Sb preferably satisfies the range of 0.05% to 0.5%.

Next, the reasons for defining the component range of the present invention will be described. The inventors have conducted intensive studies and found that C, N,
Ti, V, Nb, Z in addition to S, Cr, Cu, Sn, O
It has been discovered that by comprehensively controlling the content of impurities such as r, As, and Ca, iron loss in products can be significantly improved, and the present invention has been completed.

The following experiments were conducted to confirm the requirements of the present invention. Steel having the components shown in Tables 1 and 2 was melted and subjected to finish hot rolling to finish to a thickness of 2.5 mm. At this time, the hot rolling finishing temperature was in a γ phase region of 960 ° C. This was wound around a coil at 700 ° C. Next, pickling the hot rolled sheet,
After cold rolling to a thickness of 0.5 mm, degreased, and then annealed at 750 ° C. for 30 seconds, the Epstein sample was cut and the magnetic properties were measured.

[0033]

[Table 1]

[0034]

[Table 2]

In Tables 1 and 2, in Comparative Examples 1 to 3, the Q value did not satisfy the constituent requirement of the present invention, ie, -4.70 or less. It does not satisfy the constituent requirement of 0.003% or less, so that the iron loss is worse than that of the present invention. By controlling the impurity elements in this way, it is possible to reduce iron loss in products and to manufacture non-oriented electrical steel sheets having excellent magnetic properties.

The steel slab composed of the above components is produced in a converter and is produced by continuous casting or ingot-bulking rolling. The steel slab is heated by a known method. In the present invention, the hot-rolled sheet is made into a product by one cold rolling and continuous annealing. Further, a skin pass rolling step may be added to obtain a product. Further, the final thickness may be obtained by performing cold rolling two or more times with intermediate annealing. Furthermore, a skin pass may be performed thereafter to obtain a final thickness. If the skin pass rolling ratio is less than 2%, the effect cannot be obtained, and if the skin pass rolling ratio is 20% or more, the magnetic properties are deteriorated.

Next, the process conditions of the present invention will be described. In the prior art, the main focus has been on increasing the grain size of the hot-rolled sheet, that is, before cold rolling, as much as possible, and the transformation from γ phase to α phase after hot rolling It is considered harmful for miniaturization, and the hot rolling finish temperature is set to Ar ₁
When the temperature is raised to more than the point, the hot-rolled crystal structure is rather fine-grained, so that the use of the method of raising the hot-rolling finishing temperature to the γ region as in the present invention was not omitted. However, as a result of intensive studies, the inventors found that C, N, S, Cr, Cu, Sn, O
In addition, by reducing the content of impurities such as Ti, V, Nb, Ca, Zr, and As while satisfying the Q value defined by the formula (1) below a certain value, the finish rolling in the hot rolling process can be performed by Ar. It was discovered that even when the treatment was completed at ₃ or more, the hot-rolled crystal structure was coarsened, and as a result, the magnetic properties of the product could be significantly improved, and the present invention was completed.

The following experiment was conducted to examine the difference in the hot rolled crystal structure formation under the hot rolling conditions depending on the purity of the steel. Steels having the components shown in Table 3 were melted and subjected to finish hot rolling. The hot-rolling finishing temperature was in the range of 800 ° C. to 1000 ° C., and was finished to a thickness of 2.5 mm. This was pickled, cold rolled to a thickness of 0.5 mm, degreased, and annealed at 720 ° C. for 30 seconds to cut the Epstein sample and measure its magnetic properties. Change in hot-rolled sheet crystal grain size to hot-rolling finishing temperature, product iron loss,
The product magnetic flux densities are shown in FIGS. 1, 2 and 3, respectively.

[0039]

[Table 3]

In the high purity steel of the component 1, the hot rolling finish temperature is A
Although the hot-rolled crystal structure is coarsened even at r ₃ or more, each component in the comparative material of the component 2 satisfies the conditions other than the formula (1), but the Q value defined by the formula (1) Is higher than -4.70, and when the hot-rolling finishing temperature is equal to or higher than the Ar ₁ point, the hot-rolled crystal structure becomes finer. As a result, in the high-purity steel of the component 1, the iron loss decreases and the magnetic flux density increases as the hot-rolling finishing temperature increases, but in the comparative example of the component 2, the magnetic properties such as the increase of the iron loss and the decrease of the magnetic flux density are increased. Deterioration is seen.

Thus, C, N, S, Cr, Cu, S
In addition to reducing impurities such as Ti, V, Nb, Ca, Zr and As in addition to n and O, the Q value defined by the equation (1) is reduced by-
High-purity steel is finished at a hot-rolling finishing temperature of at least _three points of Ar under the control of 4.70 or less to reduce iron loss in products, increase magnetic flux density, and provide non-directional electromagnetic It is possible to manufacture steel sheets.

A steel slab composed of the above components is produced by melting in a converter and being 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. At this time, the finishing temperature of the finish hot rolling is set to ₃ points or more of Ar. Winding temperature is 680
When the temperature is at least ° C, the coarsening of the hot-rolled crystal structure in the present invention can be further promoted.

When the hot-rolling finishing temperature is lower than the Ar ₃ point, the growth of the hot-rolled crystal structure becomes insufficient, and the non-oriented electrical steel sheet having excellent magnetic properties aimed at by the present invention cannot be obtained. For this reason, the hot rolling finishing temperature needs to be at least Ar ₃ points. Although there is no particular upper limit on the hot rolling finish temperature, the upper limit is inevitably determined by the upper limit of the slab heating temperature during hot rolling and the hot rolling schedule.

If the winding temperature is 680 ° C. or lower, the growth of the hot-rolled crystal structure becomes insufficient, and a non-oriented electrical steel sheet having excellent magnetic properties cannot be obtained. For this reason, the winding temperature is preferably at least 680 ° C, more preferably at least 700 ° C.

The hot rolled sheet obtained in this manner is made into a product by one cold rolling and continuous annealing. Further, a skin pass rolling step may be added to obtain a product. If the skin pass rolling ratio is less than 2%, the effect cannot be obtained, and if the skin pass rolling ratio is 20% or more, the magnetic properties are deteriorated.

[0046]

Next, an embodiment of the present invention will be described. [Example 1] A slab for non-oriented electrical steel having the components shown in Table 4 was heated by a usual method, and was hot-rolled to 2.5 mm.
Finished. At this time, the hot rolling finishing temperature is 960 ° C.
All were in the γ phase region at or above the Ar ₃ transformation point. The winding temperature of hot rolling was 700 ° C. Then, it was pickled and finished to 0.50 mm by cold rolling. This is placed in a continuous annealing furnace 73
Annealed at 0 ° C. for 30 seconds. Thereafter, the sample was cut into Epstein samples, and the magnetic properties were measured. Table 4 also shows the components of the present invention and comparative examples and the results of iron loss measurement.

[0047]

[Table 4]

Comparative Example 1 had a Q value, Comparative Example 2 had a C content, Comparative Example 3 had an S content, Comparative Example 4 had a Ti content, Comparative Example 5 had a V content, Example 6 shows that the Nb content is
Comparative Example 7 has an S and As content, Comparative Example 8 has a Cr content, Comparative Example 9 has a Sn content, Comparative Example 10 has a Cu content, and Comparative Example 11 has an O content of the present invention. Does not meet the configuration requirements, compared to the embodiment of the present invention magnetic flux density,
It turns out that the value of iron loss is inferior.

By controlling the purity of the steel as described above, the non-oriented electrical steel sheet having a high magnetic flux density and a low iron loss value and excellent magnetic properties can be obtained by setting the winding temperature to Ar ₃ points or more. It is possible to get.

Example 2 A slab for non-oriented electromagnetic steel having the components shown in Table 5 was heated by a usual method and finished to 2.5 mm by hot rolling. At this time, the hot-rolling finishing temperature was set to two levels of 965 ° C. at ₃ points or more of Ar and 850 ° C. at Ar ₁ or less,
The winding temperature was set to 700 ° C. by cooling control.

After that, it is pickled and then cold-rolled to a thickness of 0.1 mm.
Finished to 50 mm and 0.55 mm. The sheet having a thickness of 0.50 mm was annealed in a continuous annealing furnace at 730 ° C. for 30 seconds. Thereafter, annealing was performed at 750 ° C. for 2 hours corresponding to a customer. In addition, the one with a sheet thickness of 0.55 mm is 700 ° C in a continuous annealing furnace.
At 750 ° C. for 2 hours, followed by annealing at 750 ° C. for 2 hours. From these samples, Epstein test pieces were cut out to measure the magnetic properties.

[0052]

[Table 5] Tables 6 and 7 also show the hot rolling finish temperature, winding temperature, and magnetic measurement results of the present invention and the comparative examples described in the examples.

[0053]

[Table 6]

[0054]

[Table 7]

As described above, by using a high-purity steel and setting the hot-rolling finishing temperature to ₃ points or more of Ar, a material having a high magnetic flux density and a low iron loss value can be obtained in both the single pass method and the skin pass rolling method. You can see that.

[0056]

As described above, according to the present invention, it is possible to manufacture a non-oriented electrical steel sheet having high magnetic flux density and low iron loss and excellent in magnetic properties.

[Brief description of the drawings]

FIG. 1 is a chart showing a relationship between a hot-rolling finishing temperature and a hot-rolled sheet crystal grain size in the present invention.

FIG. 2 is a chart showing a relationship between a hot rolling finish temperature and a product iron loss in the present invention.

FIG. 3 is a table showing a relationship between a hot rolling finish temperature and a product magnetic flux density in the present invention.

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 4K033 AA01 CA01 CA02 CA03 CA05 CA07 CA10 FA03 FA04 FA10 HA01 5E041 AA02 AA11 AA19 CA04 HB05 HB07 HB11 NN01 NN17 NN18

Claims (3)

[Claims] 1.% by weight: 0.1% ≦ Si ≦ 3.5%, 0.1% ≦ Mn ≦ 1.5%, C ≦ 0.004%, N ≦ 0.002%, S ≦ 0 0.002%, Ti ≦ 0.003%, Nb ≦ 0.003%, V ≦ 0.005%, Zr ≦ 0.003%, Ca ≦ 0.003%, As ≦ 0.003%, Cr ≦ 0. 0.05%, Sn ≦ 0.01%, Cu ≦ 0.05%, O ≦ 0.02%, with the balance being Fe and unavoidable impurities,
A slab having a α-γ transformation with a Q value determined by the formula (1) of -4.70 or less is hot-rolled into a hot-rolled sheet, then subjected to one cold rolling step, and then subjected to finish annealing, and thereafter A method for producing a non-oriented electrical steel sheet which is subjected to a skin pass rolling step or not, wherein a hot-rolling finishing temperature is set to ₃ points or more, wherein the magnetic flux density is high and the iron loss is low. Steel sheet manufacturing method. Q = log [([Ti%] + [Nb%] + [V%] + [Zr%] + [Ca%]) × [C%]] Equation (1) where [Ti%], [Nb%], [V%], [Zr%], [C%], [Ca%]
Is the weight concentration of Ti, Nb, V, Zr, Ca, and C in the product, respectively. 2. A non-oriented electrical steel sheet having a high magnetic flux density and a low iron loss according to claim 1, wherein the slab further contains 0.1% ≦ Al ≦ 2% by weight. Law. 3. The method for producing a non-oriented electrical steel sheet having a high magnetic flux density and a low iron loss according to claim 1, wherein the hot-rolled sheet after the finish hot rolling is wound at a temperature of 680 ° C. or higher. .