JP2000160306A - Non-oriented silicon steel sheet excellent in workability and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a silicon steel sheet excellent in workability such as punchability, machinability or the like. SOLUTION: This steel sheet has a chemical compsn. composed of, by weight, <=0.01% C, 0.01 to 4.50% Si, 0.0001 to 4.00% sol.Al, 0.05 to 4.00% Mn, <=0.15% P, 0.005 to 0.035% S, and the balance Fe with inevitable impurities, in which inclusions in the steel sheet are composed of oxide inclusions, sulfide inclusions, and composite inclusions of both, the size of each inclusion is >=2 μm, 2 to 10 pieces of the inclusions form a group so as to be connected in a row, and the total of the number of the inclusions of >=2 μm grain size is controlled to >=10% to the number of the inclusions of >=0.1 μm grain size. As for the producing method, molten steel is subjected to vacuum treatment to control the contents of C, P and S to the ranges in the above chemical compsn., the content of dissolved oxygen is controlled to 0.01 to 0.07 wt.%, next, the contents of sol.Al and Si are controlled to the ranges in the above chemical compsn., then, the content of Mn is controlled to the range in the above chemical compsn., and, after that, casting, hot rolling, cold rolling and annealing are executed according to the conventional methods.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic steel sheet used as an iron core of electric equipment, and more particularly, to a rotor of a rotating machine,
The present invention relates to a non-oriented electrical steel sheet excellent in punching workability and lathe workability when used as a stator.

[0002]

2. Description of the Related Art Magnetic steel sheets are used as core materials for stationary equipment such as transformers and stabilizers, and for rotating machines such as electric motors and generators. Such a material is required to have excellent magnetic properties, but at the stage of manufacturing an iron core, it is also required to have good workability such as punchability when punching into a predetermined shape and machinability in lathe processing. . However, hitherto, the machinability of the non-oriented electrical steel sheet has been seldom regarded as important as compared with the punching property and the caulking property.

[0003] The rotor and the stator of the rotating machine are formed by punching out electromagnetic steel sheets, laminating them, and then performing cutting with a lathe in order to improve the dimensional accuracy of the air gap between the rotor and the stator. In particular, the rotor iron core often performs high-precision cutting because dynamic balance during rotation is important. If a material having poor machinability is used, the frequency of changing the cutting tool in the stage of manufacturing the iron core increases, and workability and production cost decrease.

On the other hand, in a material having poor machinability, burrs are easily generated by cutting. The rotor or the stator is provided with a groove for forming a magnetic pole, and burrs are easily generated at the edge or end of the groove. If the core is assembled into a rotating machine while cutting burrs are left, there is a risk that an electrical short circuit may occur between the laminations of the iron cores, resulting in an increase in iron loss or overheating of the iron core. Alternatively, the burrs are peeled off and are caught in the air gap between the rotor and the stator, causing damage to the lamination and dielectric breakdown of the coil. Therefore, it is necessary to remove cutting burrs before assembling. However, this deburring operation has problems such as extra work steps, necessity of a deburring facility, and impairment of handling safety. .

Therefore, there is a need for an electromagnetic steel sheet which is easy to cut and hardly generates burrs. In response to this request, for example, the following technology has been proposed.

Japanese Patent Publication No. 54-1169 discloses a notch effect by adding graphite to an electromagnetic steel or an electromagnetic steel sheet.
It is stated that a lubricating effect is produced and the machinability is improved, but the addition of graphite is not preferable because it adversely affects the magnetic properties of the steel sheet.

Japanese Patent Application Laid-Open No. 4-293724 discloses that the addition of P to a steel sheet improves the machinability without deteriorating the magnetic properties of the non-oriented electrical steel sheet.
In order to compensate for the decrease in toughness due to the addition, extremely low C and extremely low S are required, and the cost of de-C and de-S increases, and
There is a restriction that i + Al <1.5%, and there is a problem that the addition amount of Si which is a basic component of the electromagnetic steel sheet is restricted.

[0008] Japanese Patent Application Laid-Open No. 5-331602 discloses a technique in which the amount of Mn and Al in a steel sheet is regulated to adjust the hardness of the steel sheet to maintain the machinability. However, sufficient machinability cannot be obtained simply by maintaining the value.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems of the prior art, an object of the present invention is to provide an electromagnetic steel sheet which is excellent in punching and cutting properties and excellent in magnetic properties.

[0010]

Means for Solving the Problems The present inventors have prepared a non-oriented electrical steel sheet for a rotor that uses a lot of punching and cutting work by melting raw steel under various manufacturing conditions and performing various rolling and annealing processes. Test materials were prepared under the conditions. For these test materials,
A sample was punched and laminated in the shape of a rotor having a notch on the outer periphery, and punching and a cutting test were performed. Hereinafter, when referred to as workability, punchability and machinability are collectively referred to.

FIG. 1 is a schematic view showing the form of inclusions in a steel sheet having good workability. As shown in the figure, in the steel sheet having good workability, the grain size of the inclusions is as large as 2 μm or more,
They formed a group of rows, and many cases where sulfides adhered to the surface were observed. As can be inferred from the figure, in this embodiment, the inclusions generated in the steel making process are broken and elongated in the rolling process.

However, it was also found that those having extremely long continuous line-shaped inclusions had poor magnetic properties even with good workability.

On the other hand, it was found that even when the number density of the inclusions was the same, the distribution of the inclusions had no directionality, and the ones dispersed uniformly had poor workability.

That is, in conventional magnetic steel sheets or general steel sheets, efforts have been made to reduce impurities as much as possible. However, in order to improve workability while maintaining magnetic properties, a moderate amount of interposition is required. It has been found that it is only necessary to control the composition and form within a certain range in the presence of an object.

The gist of the present invention completed on the basis of the above findings is as follows (1) and (2). (1) Chemical composition by weight%, C: 0.01% or less, Si:
0.01-4.50%, sol.Al: 0.0001-4.
00%, Mn: 0.05 to 4.00%, P: 0.15%
Hereinafter, S: 0.005 to 0.035:%, the balance is Fe and unavoidable impurities, and the inclusions in the steel sheet are oxide-based inclusions, sulfide-based inclusions, and composite inclusions of both. The form of the inclusions is a group in which two to ten inclusions having a particle size of 2 μm or more are arranged in a row,
A non-oriented electrical steel sheet excellent in workability, characterized in that the total number of inclusions having a particle diameter of 0.1 μm or more is 10% or more of the number of inclusions having a particle diameter of 0.1 μm or more.

(2) The molten steel is subjected to a vacuum treatment by C: 0.01% by weight or less, P: 0.15% by weight or less, S: 0.005 to
0.035% by weight, dissolved oxygen amount 0.01 to 0.07% by weight, then sol. Al: 0.001 to 4.00% by weight, Si: 0.01 to 4.50% by weight. Later, M
n: 0.05 to 4.00% by weight, a method for producing a non-oriented electrical steel sheet having excellent workability, comprising casting a steel piece and hot rolling and cold rolling the steel piece. .

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The reasons for limiting each factor and condition in implementing the present invention will be described below. In addition, the following% display means weight%.

(1) Chemical composition of steel C: 0.01% or less C is preferable to be as small as possible because C deteriorates magnetic properties. The upper limit is set to 0.
01%. Although the lower limit of the C content is not particularly defined, it is preferably 0.003 or more in consideration of the decarburization cost. More preferably, it is 0.005 to 0.008%.

Si: 0.01 to 4.50%, which is a commonly used component in deoxidizing steel and is effective for increasing the electrical resistance of steel and reducing iron loss. In order to secure the deoxidizing effect and the magnetic properties, the lower limit of the Si content is set to 0.0.
1%. On the other hand, as the Si content increases, the magnetic flux density decreases and the rollability deteriorates, so the upper limit is 4.5%.
And Preferably it is 0.03-3.0%.

Mn: 0.05 to 4.00%, S is fixed as sulfide, and Mn is contained in an amount of 0.05% or more to prevent hot brittleness due to S. Like Mn, Mn is effective in increasing the electrical resistance of steel to reduce eddy current loss, but as the content increases, the magnetic flux density decreases and the rollability deteriorates. 00%. Preferably it is 0.10-2.00%.

P: 0.15% or less The effect of increasing electric resistance to improve iron loss and hardening steel to improve punchability. For this reason, when emphasizing the punching property, P may be contained. However, an excessive content will make the steel brittle, so the upper limit is 0.15%.
And Preferably it is 0.10% or less.

Sol. Al: 0.0001 to 4.00%, Al in the present invention functions as a deoxidizer for molten steel for obtaining a healthy steel, and controls the amount of Al ₂ O _{3 in} inclusions. Has the role of increasing the electrical resistance of steel and reducing iron loss. Some of the deoxidation products generated by the addition of Al float, but the remainder forms oxide inclusions in the steel, and excess Al remains in the steel as sol.Al.

If the sol.Al content is 0%, the content of Al ₂ O ₃ as an effective inclusion cannot be ensured, so the lower limit is 0.00.
01%.

On the other hand, as the sol.Al content in the steel increases, the magnetic flux density decreases and the rollability deteriorates, so the upper limit is set to 4.00%. It is preferably 0.0005 to 2.00% in view of cost and the like.

When Si and Al are simultaneously contained, from the viewpoint of cold rolling properties, the Al content is set to Si + 0.5 sol. Al ≦
It is desirable to be in the range of 4.5%. S: 0.005 to 0.035% S degrades the magnetic properties but has the effect of improving the workability of the steel sheet. When workability is important, S is 0.00
It is preferable to contain 5% or more. But even in that case, S
If the content is excessive, sulfide inclusions and precipitates increase, and the effect of deteriorating magnetic properties becomes too strong,
Its content should be 0.035% or less.

(2) Inclusions The presence form of the inclusions greatly affects the magnetic properties of the steel sheet through the growth behavior of recrystallized grains of the steel sheet, and also greatly affects the workability. In the present invention, a method has been found in which both properties can be satisfied by utilizing inclusions.

(A) Particle size of inclusions The smaller the particle size of the inclusions, the easier it is to pin (fix) the grain boundaries during crystal grain growth, which adversely affects the grain growth. Therefore, the particle size of the inclusions is preferably 2 μm or more. Here, the particle size is equivalent to the diameter of a circle having the same area. If the total volume of the inclusions is the same, the larger the inclusion particle size, the smaller the total number of inclusions, which is preferable for the grain growth. Therefore, the upper limit of the particle size of the inclusions is not particularly defined because it is determined in consideration of the grade of the magnetic properties that is correlated with the grain growth of the steel sheet.

(B) Form of Inclusions The role of inclusions in improving the workability (punching and cutting properties) is that when the machining tool comes into contact with the material, the inclusions serve as starting points for cracking and provide a notch effect. And work to promote the shearing of the tool. Further, at the time of cutting, the sulfide-based inclusion has a function of giving a lubricating effect to the tool and suppressing tool wear.

According to the observations made by the inventors, the existence form of the inclusions includes a form in which the particles are individually dispersed and a form in which the particles are arranged in a row. The form of inclusions preferable for workability is more suitable for forming a group than for the inclusions being finely and uniformly dispersed. This is because it is more appropriate to form a group by dispersing it moderately coarsely than in a densely populated community. (A) The number of contact points and area of tools during processing increases, and the number of crack origin sites increases. (B) cracks are easily propagated between the starting sites,
It has a synergistic effect in the notch effect.

On the other hand, if the number of continuous inclusions is excessively long, the grain growth of steel is impaired, so that the magnetic properties deteriorate.

According to the test results of the inventors, it was found that the magnetic characteristics would not be deteriorated if the number of the group-shaped inclusions was 10 or less.

Further, in order to form a group of 2 to 10 continuous inclusions having a grain size of 2 μm or more in the steel sheet after hot rolling and cold rolling, it is necessary to include inclusions in the steel at the time of solidification of the molten steel. It was found that the particle size of the particles had only to be about 4 to 15 μm.

It is considered that the difference in the existence form of the inclusions is caused by whether fine particles are uniformly dispersed or particles of a certain size are sparsely dispersed in the solidification stage of the molten steel. Further, it is considered that when inclusions are deformed by rolling, some of the inclusions are easily elongated and others are not easily elongated. Generally, particles having a high melting point are less likely to elongate during hot rolling, while particles having a lower melting point are elongated during hot rolling and are easily broken during cold rolling. Further, among the inclusion particles, particles that are easily broken are considered to be finely broken and elongated finely. On the other hand, high strength particles are not destroyed by rolling and do not elongate. As described below, the inclusions are desirably controlled to have an appropriate inclusion composition determined in the refining stage, prior to the slab solidification stage. The composition of the inclusion is closely related to the mechanical properties, and controlling the composition is because the morphology of the inclusion is controlled by processing.

From the above viewpoints, when the large inclusions of 2 μm or more are arranged in a row of 2 or more and 10 or less, both workability and magnetic characteristics can be achieved.

The state in which the inclusions are arranged in a row means that the inclusions in the steelmaking stage are stretched and split in the rolling process to be in a state of being arranged in a row as described above, and the particle size is 2 μm or more. The inclusions having an interval of 2 μm or less are regarded as a group of inclusions. This is because if the distance between the inclusions exceeds 2 μm, it is not considered that the same steelmaking inclusion was originally broken and elongated.

The means for observing inclusions is suitably observed at a magnification of about 100 to 1000 times with an optical microscope or a scanning electron microscope. When the polished surface of the specimen observed by a microscope is parallel to the rolling direction, a series of inclusions can be well observed.

When the inclusions are connected in the visual field of the microscope, most of the inclusions have such a form.
It is rare to see a mixture of individually dispersed inclusions and continuous inclusions. On observation, for example, a series of inclusions in a group of about 50 rows can be seen at the maximum in a visual field of 400 magnification. However, if there are five or more groups, it can be determined that row-shaped inclusions are generated.

(C) Number of Inclusions According to the study of the present inventors, inclusions that affect magnetic properties, that is, inclusions that pin the crystal growth during the annealing process, have a grain size of 0.1 μm or more. is there.

According to the present invention, if the number of inclusions in a row having a particle diameter of 2 μm or more is 10% or more of the total number of inclusions (particle diameter of 0.1 μm or more), predetermined characteristics are satisfied. be able to.

(D) Inclusion Composition The inclusions observed in the magnetic steel sheet in the chemical composition of the present invention include oxide inclusions, sulfide inclusions, and composite inclusions of both.

According to the study of the present inventors, some test pieces excellent in workability have sulfide-based inclusions alone, but most of the sulfide-based inclusions are oxide-based inclusions. It has been found that a large number of nuclei are precipitated on the nuclei. In other words, it is considered that the inclusion in which the oxide is covered with the sulfide has a lubricating effect on the punching tool and the cutting tool. Therefore, as described above, an appropriate S content is defined.

The composition of the inclusions forming the above-described inclusion morphology is desirably a specific composition from the viewpoint of mechanical properties and melting point. In other words, if inclusions with a relatively high melting point are coarsely precipitated during the casting stage, the inclusions are appropriately broken, stretched, and stretched in a row when hot rolling and cold rolling steel. It is because it becomes.

An example of the composition is as follows.
₂ O ₃ , SiO ₂ , MnO, CaO, MgO, Ti
One or more types of inclusions such as O ₂ and ZrO ₂
It is desirable that sulfide-based inclusions, such as MnS, CaS, ZrS, and FeS, which are a simple substance and two or more of them are compositely deposited, are deposited.

The composition of inclusions can be analyzed by energy dispersive X-ray analysis. In addition, as a chemical analysis method, the oxide component can be quantitatively analyzed by extraction separation and quantification by a bromine-methanol method, and the sulfide component can be quantitatively analyzed by a potentiostatic electrolysis method.

(3) Manufacturing Method As described above, in the steel slab of the magnetic steel sheet of the present invention, it is necessary to disperse inclusions having a moderately large particle size, and the types of inclusions are large. Desirably, those which are easy to obtain and are appropriately broken in the rolling step are preferable, and sulfides, oxides or composites thereof are mainly deposited.

The method for producing the magnetic steel sheet of the present invention is as follows. C: 0.01% by weight or less, P: 0.15% by weight or less in vacuum processing of molten steel produced in a converter or an electric furnace,
S: 0.015 to 0.035% by weight;
0.01 to 0.07% by weight, and then sol.
The content is adjusted to 0.01 to 4.00% by weight and Si to 0.01 to 4.50% by weight, and then to Mn: 0.05 to 4.00% by weight.

There is no special restriction on the means of vacuum processing in the present invention. Conventionally commonly used RH degassing equipment, VOD or tank degassing equipment, etc.
Any device can be used as long as it can be processed in a vacuum of 1 atm or less.

In the production method of the present invention, C:
0.01% by weight or less, dissolved oxygen amount of 0.01 to 0.07
The degree of vacuum and the processing time are adjusted so as to be in the range of%.

This condition is such that inclusions having a particle size of 2 μm or more are ensured in the steel sheet by the subsequent deoxidation treatment with Al and Si, and the number of the inclusions having a particle size of 2 μm or more is reduced to 0.1%.
This is for controlling the number of inclusions of at least 10 μm to at least 10%.

When the oxygen concentration is less than 0.01%, it is difficult to reduce the carbon concentration to 0.01% or less by vacuum treatment. In addition, the addition of Al and Si in the steel
Even if inclusions such as l ₂ O ₃ and SiO ₂ are formed, many fine inclusions are formed, and it becomes difficult to secure inclusions having a grain size of 2 μm or more in the steel sheet. That is, a particle size of 2 μm
The number of inclusions described above is less than 10% of the number of inclusions having a particle size of 0.1 μm or more. When the oxygen concentration exceeds 0.07%,
A large amount of time is required for the deoxidation treatment under a vacuum with Al and / or Si, and the deoxidation becomes insufficient, and a large amount of inclusions are generated, which causes deterioration of magnetic properties. Preferably, the amount of dissolved oxygen is 0.02 to 0.04%.

Here, the amount of dissolved oxygen in the molten steel is the amount of oxygen dissolved in the molten steel. Before the addition of Si and / or Al, the amount of dissolved oxygen is directly measured from the molten steel using an oxygen sensor applying the principle of an oxygen concentration cell. Can be measured.

The degree of vacuum may be controlled to a level at which decarburization can be performed within a predetermined time, but is preferably set to 0.01 atm or less. If the processing time has a margin, the degree of vacuum may be about 0.05 atm.

Then, under vacuum or after vacuum treatment, A
1 source and Si source are added. Al and Si are added after adjusting the concentrations of carbon and oxygen as described above. Al source, Si
The sources may be added separately or simultaneously. In order to obtain moderately sized inclusions in the steel with the oxygen concentration adjusted in advance, the Si source is added after the addition of the Al source.
It is desirable to add a source.

Next, a Mn source is added. By adding Mn after adding Al and Si, the amount of Mn oxidized and transferred to slag is reduced, the yield of Mn is improved, and Mn is improved.
Adjustment of the content is also easy.

Further, if the Mn content is adjusted by this method, the Mn content can be gradually increased from a low state.
MnO components in inclusions that lower the melting point can be suppressed. That is, most of the Mn component combines with S to form a sulfide, and the generated sulfide is generated so as to cover around the previously generated oxide-based inclusion.

According to the method of the present invention, if steel is produced using ordinary hot metal or scrap as a main raw material, there is no need to adjust the S content in the steel. However, in the case where emphasis is placed on workability such as punchability and machinability, it is desirable to contain a large amount of S. Therefore, after adding Al and Si, sulfur such as Fe-S is added before adding Mn. The contained ferromagnetic iron may be added. If the addition of these Al source, Si source, S source, and Mn source is performed in a vacuum chamber, the yield of ferroalloys is improved.

The molten steel whose chemical composition and inclusion composition are adjusted as described above is made into a slab by a continuous casting method or the like, and is made into an electrical steel sheet through processes such as hot rolling, cold rolling and annealing by a conventional method. .

Although the hot rolling conditions are not particularly specified,
If the heating temperature is too high, the inclusions do not melt and become coarse particles, so the heating temperature is desirably 1250 ° C or less, and more desirably 1200 ° C or less.

Thereafter, pickling, cold rolling, or, if necessary, warm rolling, annealing, or, if necessary, re-cold rolling and re-annealing are performed.

If necessary, annealing may be performed after hot rolling. All anneals may be batch anneals or continuous anneals, but continuous anneals that are easy to control are desirable. The final annealing temperature is 750 to 1100 ° C. in order to provide predetermined magnetic properties.
It is desirable that

[0061]

EXAMPLE A steel having a chemical composition range defined by the present invention;
Steel outside the chemical composition range specified by the present invention was produced in the steps of converter, RH type vacuum treatment, and continuous casting. Table 1 shows the ladle analysis values of these steels.

[0062]

[Table 1]

After adjusting the amount of dissolved oxygen and the carbon concentration in the molten steel by using an RH degassing apparatus, these steels were subjected to Al source, S
The chemical composition of the steel was adjusted by adding the i source, the S source, and the Mn source. The molten steel was continuously cast into slabs having a thickness of 230 mm, these slabs were heated to 1120 ° C., and the finishing temperature was 87
A steel plate of a test piece hot-rolled to a thickness of 2.3 mm at a temperature of 0 to 890 ° C. and a winding temperature of 660 to 680 ° C. was pickled and then cold-rolled to a thickness of 0.50 mm. After rolling, continuous annealing was performed at 850 ° C. for 1 minute. Thereafter, a surface insulating coating made of a composite composition containing an organic component and an inorganic component similar to that of a normal non-oriented electrical steel sheet was applied.

For observing the morphology and analyzing the composition of these steel sheet inclusions, a scanning microscope (SEM) and an energy dispersive X-ray
Observation of inclusion morphology in 60 visual fields randomly extracted at a magnification of 400 per steel type using a line analysis method,
Composition analysis was performed.

The width is 30 m from the rolling direction and the width direction of the steel sheet.
16 test pieces each having a length of 280 mm and a length of 280 mm were obtained, and the iron loss (W _15/50 ) and the magnetic flux density (B ₅₀ ) were determined by the Epstein test method specified in JIS-C-2550.

Further, a steel plate was punched out in a disk shape and laminated, and then a grooved-cut intermittent cutting test specimen was prepared. This test piece was cut with a lathe and the cutability was evaluated. Cutting test conditions are: cutting speed: 150 m / min, feed: 0.2 mm
/ Rev, cutting depth: 0.25 mm. The cutting tool used was a cermet chip with a breaker.

The cutting performance was evaluated by evaluating the tool wear by the average wear amount of the insert, and the wear amount per 1 km of the cutting total length was 100.
Those having a size of less than μm were judged as having good cutting properties (○), and those having 100 μm or more were judged as having poor cutting properties (×).

The punching property was also evaluated. With regard to the punching property, 200 times / min punching was performed by emulsion lubrication using a SKD-11 mold that simultaneously punches out three types of 20 mm square blanks having 0.12 mm corner radius with clearances of 5%, 8%, and 10%. Was performed, and the evaluation was made by relative evaluation of burr generation by punching. A sample having no burr after 700,000 times punching was judged as having good punching performance (（), and a sample having less than 700,000 times flashing was judged as poor punching property (x).

Table 2 shows the test results.

[0070]

[Table 2]

In Table 2, (O) in the column of the form of inclusions
In the case where five or more groups of inclusions in the form of a row are found in any of the microscope visual fields, 2 to 10 of these row-shaped inclusions occupy the majority (80% or more). Yes, (x) is when this is not the case. In the column of the average number of inclusions in the column, even if the inclusions of 2 μm or more are not in the form of a row, they are counted as one piece per row, and those in the row include inclusions of less than 2 μm. The total number of inclusions is divided by the total number of row groups. In the column of particle diameter, the average value of the particle diameters of the inclusions is calculated for each row group, and the average particle diameter is calculated for all the row groups.

As shown in the table, in Test Nos. 1 to 9,
The chemical composition and inclusion morphology were within the scope of the present invention, and the magnetic properties were good, and the cutting and punching properties were also good.

In Test No. 10, the C content was higher than the range of the present invention. This test specimen had good cutting and punching properties, but was inferior in magnetic properties.

In Test No. 11, Si was higher than the range of the present invention.
Since the amount was low, the iron loss was large and the machinability was poor.

In Test No. 12, Si was higher than the range of the present invention.
Due to the high amount, cracks occurred during cold rolling, and the investigation sample could not be collected.

In Test No. 13, Mn was larger than the range of the present invention.
The amount was high, and the inclusions were in the form of rows of 15 to 20 fine particles, deviating from the definition of inclusions. The number of inclusions having a particle size of 2 μm or more was about 3% of the number of inclusions having a particle size of 0.1 μm or more, and this point was also out of the range of the inclusions of the present invention. As a result, the magnetic properties were inferior, and the cutting and punching properties were also inferior.

In Test No. 14, the P content was higher than the range of the present invention, and cracks occurred during punching.

In Test No. 15, since the S content was higher than the range of the present invention, the workability was good, but the growth of crystal grains was poor and the iron loss was poor.

In Test No. 16, the sol.
The amount of Al was large and the magnetic properties were inferior.

In Test Nos. 17 to 23, the steel components fall within the scope of the present invention, but any of the form of inclusions, the number of inclusion groups, and the particle size of the inclusions fall outside the scope of the invention.

In Test No. 17, the number of inclusions arranged in a row was small and the machinability was poor.

In Test No. 18, although the inclusion group was in a row, the average number of the series was about 18, which was larger than the range of the present invention. Seem.

In Test No. 19, the form of the inclusions was not a row but a form in which a single inclusion was dispersed. The ratio of the number of inclusions of 2 μm or more to the number of inclusions of 0.1 μm or more was about 4%. Therefore, the machinability was poor. In addition, since the grain growth was suppressed, the iron loss was inferior.

In Test No. 20, the number of inclusions was larger, the size of the inclusions was smaller, and the particle size was larger than the range of the present invention.
Since the number ratio of the inclusions of 2 μm or more to the number of inclusions of 1 μm or more was about 4%, the grain growth was suppressed and the iron loss was inferior.

In Test No. 21, the size of the inclusion was 2 μm.
m or more, but few were arranged in a row, and the cutting and punching properties were poor.

Except for Test Nos. 13, 19 and 20, the particle size was 0.1.
The number ratio of inclusions of 2 μm or more to the number of inclusions of 1 μm or more was 10 to 15%.

[0087]

The non-oriented electrical steel sheet according to the present invention exhibits excellent magnetic properties, punching properties and cutting properties, prolongs the life of punching dies and cutting tools, and eliminates the occurrence of punching burrs and cutting burrs. In addition, the work efficiency is improved, and the deburring work can be omitted. According to the production method of the present invention,
The non-oriented electrical steel sheet can be stably manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the form of inclusions in a steel sheet having good workability.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroyoshi Yasu 4-3-33 Kitahama, Chuo-ku, Osaka City Inside Sumitomo Metal Industries Co., Ltd. (72) Inventor Yasutaka Okada 4-5-33 Kitahama, Chuo-ku, Osaka-shi F-term in Sumitomo Metal Industries, Ltd. (reference) 4K033 AA01 CA08 CA09 5E041 AA02 AB19 CA04 HB19 NN01

Claims (2)

[Claims] 1. Chemical composition in weight%, C: 0.01% or less, Si: 0.01 to 4.50%, sol. Al: 0.00
01 to 4.00%, Mn: 0.05 to 4.00%, P:
0.15% or less, S: 0.005 to 0.035:%, the balance being Fe and unavoidable impurities, the inclusions in the steel sheet are oxide-based inclusions, sulfide-based inclusions, and composites of both. In the form of the inclusions, the inclusions form a group in which 2 to 10 inclusions having a particle size of 2 μm or more are arranged in a row, and the total number of the inclusions having a particle size of 2 μm or more is 0. 1μ
A non-oriented electrical steel sheet having excellent workability, characterized in that the number of inclusions is not less than 10%. 2. The molten steel is subjected to a vacuum treatment to obtain C: 0.01% by weight.
Hereinafter, P: 0.15% by weight or less, S: 0.005 to 0.5%.
035% by weight, dissolved oxygen content 0.01 to 0.07% by weight
Then, after sol. Al: 0.001 to 4.00% by weight and Si: 0.01 to 4.50% by weight, Mn:
A method for producing a non-oriented electrical steel sheet excellent in workability, characterized in that the steel slab is cast into a slab, and the slab is hot-rolled and cold-rolled.