JP2003027193A - Nonoriented silicon steel sheet having excellent calking property - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonoriented silicon steel sheet which has excellent calking properties. SOLUTION: The nonoriented silicon steel sheet having excellent calking properties has a composition containing, by mass, <=0.005% C, <=4% Si, <=1.5% sol.Al, <=2% Mn, <=0.2% P, <=0.01% (inclusive of zero) S, <=0.005% (inclusive of zero) N and <=0.004% (inclusive of zero) O, and the balance substantially Fe, and in which, among inclusions observed in the cross section of the steel sheet, the number of the ones having a diameter of 1.5 to 5 μm is <=40 pieces/mm<2> , and the number of the ones having a diameter of >=5 μm is <=2 pieces/mm<2> .

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 excellent crimpability, which is suitable for use as a core material for motors and transformers.

[0002]

2. Description of the Related Art Non-oriented electrical steel sheets, which are widely used as iron core materials for motors and transformers, are used by laminating steel sheets. Therefore, caulking fastening is often used as a fastening method for laminated steel sheets. This caulking fastening is a continuous punching process in which a convex portion with a width of several millimeters is formed on the steel sheet by hand punching, and then the continuous automatic caulking process is used to fit the convex hand punched portion into the upper and lower steel sheets. Is a method of concluding.

Conventionally, rivet type caulking fastening in which an aluminum bar having a diameter of 1 to 2 mm is pressed and fastened, and fastening using laser welding or TIG welding have been widely performed, but recently, productivity has been increased. From the point of view, the above-mentioned punching-type caulking fastening is the mainstream.

On the other hand, recently, as motors have become smaller and more efficient, there has been a demand for further reduction in the diameter and number of crimped portions. For example, in a spindle motor for a computer hard disk, 4-12 caulking with a diameter of about 0.5 mm is adopted for a motor with a diameter of about 3 cm.
It is required to further reduce the diameter of the crimped portion.

Further, in a motor core for a compressor, in order to improve efficiency, it is important to reduce the diameter or the number of caulking portions whose magnetic characteristics are deteriorated due to plastic deformation. Along with this, the required level of caulking has become strict, and the conventional steel sheet often causes caulking defects, which is a problem. The defective crimping is a phenomenon in which the binding force of the cores is weak and the cores are loosened until the cores crimped by the automatic crimping device are conveyed to the next step.

From such a background, further improvement of the caulking fastening method or development of a caulking property improving technique from the viewpoint of material has been earnestly desired. Conventionally, the improvement of the crimping property depends on the design and adjustment of the mold in many cases because there is little material knowledge about the crimping property. That is, the shape and number of caulking fastening portions, clearance, pushing amount (die height), etc. have been optimized for each target steel sheet. However, since the material is different for each target steel plate, the actual situation is that sufficient measures have not been taken.

[0007] On the other hand, as a technique disclosed in terms of material, for improving the caulking property, for example,
As described in Japanese Unexamined Patent Publication No. 1-315104, the coating thickness of the steel sheet is 0.3 to 0.4 μm, which is thinner than usual, and the amount of sulfide in the steel is further reduced to improve the binding force of the caulking fastening portion. As described in JP-A-5-33063, a steel sheet containing 0.015 to 0.05% of C is subjected to skin pass rolling, and then subjected to an aging treatment so that the hardness of the steel sheet becomes Hv: 135 to 165. A method of making adjustments to improve punchability and skewness can be mentioned.

[0008]

However, in the technique disclosed in Japanese Patent Application Laid-Open No. 1-315104, the binding force is improved by reducing the film thickness, but the die wear is increased. In many cases, even if S is reduced, the caulking property is not always improved. In other words, a steel plate that has a relatively high caulking and cohesive strength despite its high S,
Although the steel sheet was found to have many crimping defects despite its low value, it was necessary to elucidate the controlling factors other than S for the crimping property.

On the other hand, in the technique disclosed in Japanese Patent Laid-Open No. 5-33063, since a large amount of C is contained and skin pass rolling is essential, even if the caulking property is excellent, excellent magnetic properties are obtained. Is difficult to grant.

Many techniques focusing on punchability have been disclosed, but most of them relate to reduction of die wear by adjusting hardness and improvement of outer peripheral dimension accuracy of punching core, and improvement of binding force of caulking portion. It did not give any knowledge about.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a non-oriented electrical steel sheet having excellent crimpability.

[0012]

[Means for Solving the Problems] The first means for solving the above problems is mass%, C: 0.005% or less, Si: 4%.
Below, so1.Al: 1.5% or less, Mn: 2% or less, P: 0.2% or less, S: 0.01% or less (including 0), N: 0.005% or less (including 0), O: 0.004% or less ( Including 0),
Among the inclusions observed in the steel plate cross section, the balance being substantially Fe, and having a diameter of 1.5 to 5 μm, 40 pieces / mm ² or less,
A non-oriented electrical steel sheet having excellent crimpability, characterized in that the number of particles having a diameter of 5 μm or more is 2 pieces / mm ² or less (claim 1).

A second means for solving the above problems is
In mass%, C: 0.005% or less, Si: 4% or less, so1.Al: 1.
5% or less, Mn: 2% or less, P: 0.2% or less, S: 0.01% or less (including 0), N: 0.005% or less (including 0), O:
Includes 0.004% or less (including 0), the balance consists essentially of Fe, and the diameter is 0.2 among the inclusions observed in the steel plate cross section.
250 ~ 1500 pieces / mm ² ~ 0.6 μm, diameter 1.5 ~ 5 μm
40 pieces / mm ² or less, 2 pieces with a diameter of 5 μm or more
It is a non-oriented electrical steel sheet having excellent crimping properties (claim 2), characterized in that it is / mm ² or less.

A third means for solving the above-mentioned problems is as follows.
The first means or the second means, further comprising:
%, Mg: 0.0001 to 0.0020% is included.

A fourth means for solving the above-mentioned problems is as follows.
Any one of the first means to the third means, further characterized by containing, by mass%, Ca: 0.0001 to 0.004%, and further, the sum of S and O is 0.005% or less. (Claim 4).

In these means (claims), "the balance is substantially Fe" means that the content of other trace elements such as unavoidable impurities is included in the present invention unless the effects of the present invention are lost. It is meant to be included in the range. Further, in the present specification, all percentages indicating the components of steel are mass%.

The diameter of inclusions means the diameter of the cross-sectional shape in the cross section of the steel sheet cut along the rolling direction,
If the cross-sectional shape of inclusions is not a perfect circle,
The width is measured in two directions forming an angle, and the average value of the measured values is used.

(Process leading to the invention and reasons for limiting inclusions, main components, etc.) The inventors of the present invention have conducted extensive studies on material factors that affect the caulking property in order to improve the caulking property of the non-oriented electrical steel sheet. It was As a result, it was found that the size and amount of inclusions present in the steel had a great influence on the binding force of the caulking part in the punching type caulking fastening. The present invention has been made based on such findings.

The process leading to the present invention will be described below together with the reasons for limiting the inclusions and main components. First, in order to find out the material factors that affect the caulking property, a detailed investigation of the caulking part was performed on the core that was caulked and fastened by the user. As a result, it was found that there are steel sheets having excellent caulking properties and steel sheets having inferior hardness and crystal grain size.

When a steel sheet having poor caulking property was investigated in detail, in such a steel sheet, there was a coarse extension void originating from an inclusion inside the end face of the caulking portion formed by punching, and this was caused when caulking and pushing. It was found that cracks were generated in the surface layer of the end face and that plastic deformation was caused in the surface layer portion.

In the deformed portion, the caulking is insufficiently pushed, so that the laminated steel sheets are easily separated from each other. This phenomenon was observed not only in the case of V caulking in which both the fracture surface and the shear surface exist, but also in the case of the caulking in which no fracture surface occurs such as a round caulking.

Based on such knowledge, the present inventors considered that the inclusions might adversely affect the binding force of the caulking portion, and investigated the influence of the inclusions on the caulking binding force in detail.

First, with respect to the caulked core manufactured by the user, the relationship between the generation state of voids and the size of inclusions was investigated. As for the core material using various steel plates containing 0.1 to 3% of Si, the size and the amount of inclusions in the steel plate cross section and the existence state of voids were investigated. As a result, the above-mentioned extension voids had a grain size of 1.5 μm or more. It was found that the occurrence of the inclusions of No. 1 occurred, and the presence of the inclusions smaller than that caused almost no voids.

Therefore, the inclusions present in the cross section of the steel sheet are classified into four types of diameter 0.5 to 1 μm, 1 to 1.5 μm, 1.5 to 2 μm, and 2 μm or more, and the number of each inclusion is counted and the distribution number We investigated the relationship of tightness.

The cross section of the steel sheet is a cross section obtained by cutting the steel sheet in the rolling direction. The definition of the diameter of the inclusion is as described above. For inclusions with a diameter of 1 μm or more, the cut surface of the steel sheet was magnified 500 times by SEM and the distribution number was determined by measuring it in 50 fields or more. For inclusions with a diameter of 1 μm or less, the cut surface of the steel sheet was magnified 1000 times with SEM, and the distribution number was determined by measuring it in 80 fields or more. Furthermore, when measuring inclusions with a diameter of 1 μm or less, fine inclusions with a diameter of 0.5 μm or less were enlarged 2000 times to 5000 times, and the diameter and the number were measured. This measuring method is common to the following explanations.

As a result, it was found that the inclusions having a diameter of 1.5 μm or less hardly changed the occurrence frequency of defective crimping cores even if the amount thereof increased, and hardly affected the crimping property. On the other hand, inclusions with a diameter of 1.5 μm or more
It has been found that when the distribution amount increases, the frequency of defective crimping cores remarkably increases and the crimping property deteriorates.

Therefore, based on these findings, the diameter of 1.5
The relationship between the caulking binding force and the distribution amount of inclusions was investigated focusing on inclusions with a size of μm or more. C: 0.002%, Si:
0.2%, Mn: 0.45%, P: 0.08%, S: 0.0003 to 0.0070
%, Sol.Al: tr. To 0.27%, N: 0.002%, O: 0.0008 to
Regarding the steel containing 0.0092%, the number of inclusions with a diameter of 1.5 μm or more observed in the cross section of the steel plate was changed within the range of 5 to 83 pieces / mm ² , and the binding force of the caulking part was evaluated (this. In the specification, unless otherwise specified, the number of inclusions shown in number / mm ² indicates the number observed in the cross section of the steel sheet).

The number of inclusions was changed by adjusting the components of S, O and sol.Al, as well as adjusting the reflux time in the vacuum gas apparatus after the raw material Al was charged. Here, the binding force of the caulking part is determined by automatically punching and punching 20 discs from the obtained slit hoop with the caulking device and caulking and fastening, and then the uppermost lower plate of the laminated core is fixed with an adhesive. It was evaluated by measuring the peeling strength by fixing it to the plate and performing a tensile test. The caulking shape at this time was a flat V shape as shown in FIG. In addition, the caulked portion has a width of 1.5 mm and a length of 4 mm.

The measurement results of the peel strength are shown in FIG. From this, inclusions with a diameter of 1.5 μm or more have a great influence on the caulking binding force, and if the number of inclusions with a diameter of 1.5 μm or more is reduced to 40 pieces / mm ² or less, the caulking will be critical. It can be seen that the property is significantly improved. The number of inclusions at 40 or less measurement points plotted in FIG. 2 is 5, 8, 15, 25, 31, 36, 40 in order from the left.

Observation of the cross section of the crimped portion revealed that a number of extension voids were observed in the steel sheet having poor crimpability and that the crimping was incompletely pressed. Therefore, in order to investigate the relationship between the caulking property and the amount of inclusions in the actual motor member, 200 stator cores were manufactured from four types of steel plates with the amount of inclusions adjusted, and a caulking test was conducted. The caulking property was judged as good or bad by fixing the upper part of the stator core and lifting it up, and whether or not the weight would cause the loosening.

In addition, the shape of the stator core is a dodecagonal shape with an outer dimension of 110 mm and a side of about 30 mm, and the thickness of the steel plate is 0.5.
mm, the number of laminated sheets per piece was 180, and the yoke width and the teeth length were about 13 mm. The weight of the core was about 3.5 kg. The caulking part was a flat V caulking having a width of 1.5 mm, a length of 4 mm, and a pressing amount of one plate thickness, and four caulking binding parts were provided on the yoke part of the stator so that the intervals were even. The mold clearance was 7%. The results are shown in Table 1.

[0032]

[Table 1]

First, the number of inclusions of 1.5 μm or more is 54 / m.
In the steel plate C of m ^{2 and} the steel plate D of 83 pieces / mm ² , the binding force of the caulking part is weak, and 20 to 35% of the cores that come apart due to their own weight occur,
In order to integrate the core with the steel plate, the number of crimped portions had to be six. On the other hand, the number of inclusions is 36 / mm ²
The steel plate B of No. 1 generated the deviation at a frequency of 2%, but the deviation was eliminated by adjusting the pushing amount. In the steel plate A in which the number of inclusions was 8 pieces / mm ² , the cores were tightly bound and no loosening occurred.

As described above, the amount of inclusions is greatly related to the peel strength of the caulked portion, and inclusions of 1.5 μm or more are included.
It can be seen that the caulking property is significantly improved at 40 pieces / mm ² or less (corresponding to a peel strength of 50 N or more in FIG. 1).

However, the inventors of the present invention evaluated the caulking property by further increasing the N number, and found that there are often steel plates having extremely poor caulking property. As a result of detailed examination of the crimped portion of such a steel sheet, it was found that coarse inclusions having a diameter of 5 μm or more were present.

Therefore, the same investigation was conducted focusing on inclusions having a diameter of 5 μm or more. C: 0.002%, Si: 0.18%, M
n: 0.45%, P: 0.08%, S: 0.004 to 0.005%, so1.Al:
For steel containing 0.002 to 0.25%, N: 0.002%, O: 0.0011 to 0.0045%, the number of inclusions with a diameter of 5 μm or more is 0
It was changed in the range of up to 4.4 pieces / mm ² . Here, the number of inclusions was changed by adjusting the reflux time in the vacuum theory gas apparatus after the introduction of the raw materials Si and Al. Larger deoxidation products float and separate due to longer circulation time, and the entrainment in steel is reduced.

The results are shown in FIG. From this, diameter 5
Inclusions having a size of μm or more have an extremely large adverse effect on the caulking property, and in order to obtain good caulking property (peeling strength of 50 N or more in FIG. 3), it is necessary to reduce the number to 2 pieces / mm ² or less. Recognize. In FIG. 3, the values on the horizontal axis of the points plotted at ² points / mm ² or less are 0 (2 points), 0.6, 1.4, and 1.
6, 2 pieces / mm ² .

From the above, in the present invention (claim 1), among the inclusions present in the steel, those having a diameter of 1.5 to 5 μm are 40 / mm ² or less, and those having a diameter of 2 μm or more are 2 / mm. ^Two
Limited to:

Next, the present inventors paid attention to minute inclusions and investigated the relationship with the caulking family name. The inclusions present in the cross section of the steel sheet were classified at intervals of 0.2 μm in diameter, the number of each inclusion was counted, and the relationship between the distribution number and the caulking property was investigated. As a result, it was found that the larger the amount of minute inclusions having a diameter of 0.2 to 0.6 μm, the less the occurrence frequency of defective crimped cores. On the other hand, 0.6
No correlation with caulking was found for inclusions of μm or larger.

Therefore, pay attention to inclusions having a diameter of 0.2 to 0.6 μm.
However, regarding the relationship between the number of inclusions and the peel strength of the caulked part
investigated. The result is shown in FIG. Where the test material
Scientific components are C: 0.002%, Si: 0.2%, Mn: 0.3%, P:
0.08%, S: 0.0003 to 0.008%, sol.Al: 0.25%, N:
The amount was 0.0012 to 0.005% and O was 0.0013%. Where minute
The distribution of inclusions depends on the S and N contents and the heating temperature during hot rolling.
By changing the temperature from 1100 ° C to 1250 ° C.
It was Here, the amount of inclusions with a diameter of
15 to 20 pieces / mm^TwoRange of 5 μm or more
1 inclusion / mm ^TwoIt was below. Peel strength of caulked part
The evaluation method of is the same as the above-mentioned method.

From this, it can be seen that the peel strength of the caulked portion is improved by the presence of the amount of fine inclusions having a diameter of 0.2 to 0.6 μm in the range of 250 to 1500 pieces / mm ² . As a result of investigating the shape of the punched end surface, it was found that the dimple depth of the fractured part was shallow and the fractured surface was smoothed in the steel containing minute inclusions. In addition, the area ratio of shear planes is also increasing accordingly. It is considered that due to these effects, the peel strength of the caulked portion was improved. From the above,
It is desirable that the micro inclusions having a diameter of 0.2 to 0.6 μm be contained in the range of 250 to 1500. In FIG. 4, the horizontal axis of the points plotted in the preferred range is 250, 360, 540, 900, 1500 in order from the left.

Further, the present inventors investigated the influence of various components on the crimpability. As a result, it was found that the caulking property is improved by containing a small amount of Mg, which affects the shape of the inclusions, and the Ca-containing steel can prevent the caulking property from being lowered by reducing S and O.

The results are shown in FIGS. From Figure 5,
By containing Mg in the range of 0.0001 to 0.002%,
The crimpability is improved. In the Mg-added steel, the dispersed state of inclusions became more uniform, and the clustering of inclusions often generated in Al ₂ O ₃ disappeared. For this reason,
The occurrence of voids near the crimped portion was reduced. In addition,
The horizontal axis of the points plotted in the preferred range in FIG. 5 is 0.0001, 0.0007, 0.001 from left to right.
It is 2, 0.0016 and 0.002.

On the other hand, in the Ca-added steel, CaS and CaO are formed, and these form a complex large inclusion, so that the coarse inclusion often adversely affects the caulking property. Therefore, in the Ca-added steel, the reduction of S and O is a particularly important factor, and as shown in FIG. 6, when S + O exceeds 0.005%, the caulking property remarkably decreases. The horizontal axis of the points plotted in the preferred range in FIG. 5 is 0.0012, 0.0017, 0.0025, 0.003, 0.0 in order from the left.
It is 039 and 0.005.

Therefore, it is desirable to contain Mg in the range of 0.0001 to 0.002%, and in the Ca-added steel, S and O are added in total.
It is desirable to set it to 0.005% or less. If Ca is contained in an amount of 0.0001% or more, it forms CaS, CaO, etc., and has the effect of improving the magnetic characteristics. However, if 0.004% or more is contained, the magnetic properties and the caulking property are adversely affected, so 0.0001 to 0.004%
It is good to say

(Reason for Limiting Other Components) The reason for limiting other components will be described below. C: If C is contained in excess of 0.005%, magnetic characteristics deteriorate due to magnetic aging, so the content is made 0.005% or less. S: S forms coarse inclusions, so if the amount of S is too large, the caulking property deteriorates. Therefore, S is set to 0.01% or less (including 0%). N: N also forms coarse inclusions, so if the amount of these is too large, the caulking property deteriorates. Therefore, N is 0.005%
Below (however, including 0%). O: O easily forms large inclusions, and particularly has a great influence on the caulking property. Therefore, O is 0.004% (including 0%) or less.

Si: Si is an element that increases the strength of the steel sheet and improves the crimpability. Further, it is an element effective in increasing the specific resistance and reducing the iron loss. However, 4
If it is contained in excess of%, the punchability deteriorates. Therefore, Si is 4% or less. P: P is an element which, like Si, increases the strength and specific resistance of the steel sheet to improve the crimpability and magnetic properties. However, 0.2
If it is contained in excess of 0.2%, it will cause significant embrittlement, so 0.2%
Below. Mn: Mn is an element that increases the strength of the steel sheet and improves the crimpability. It is also an element effective in preventing red hot embrittlement during hot rolling and improving grain growth. However, if the content exceeds 2%, the magnetic properties deteriorate, so the content of Mn should be 2% or less. sol.Al: sol.Al is an element that fixes N and improves grain growth. However, even if the content is more than 2%, the effect of reducing iron loss is small and the cost is unnecessarily increased, so the content is made 2% or less.

As an element other than these, Cu, Cr, Ni, Mo, B, Sb, Sn and the like may be contained for the purpose of improving the magnetic characteristics. For example, Cu is used to improve the texture, Cr, N
i and Mo are for the purpose of increasing the specific resistance, B is for the purpose of coarsening the nitride to improve the grain growth property, or for the purpose of preventing internal oxidation of the steel sheet, and Sb and Sn are for the purpose of improving the texture. Alternatively, it can be added for the purpose of preventing oxidation or nitridation of the steel sheet surface layer. Next, the manufacturing method will be described.

In the present invention, the size and amount of inclusions,
If the specified components are within the scope of the present invention, the other manufacturing method may be a general method for manufacturing a non-oriented electrical steel sheet. That is, the molten steel blown in a converter is degassed to adjust its content to a predetermined composition, and then cast. At this time, from the viewpoint of reducing coarse inclusions, the molten steel is sufficiently refluxed after the addition of a deoxidizing material such as Al in the vacuum theory gas device, and large inclusions, especially oxide inclusions, are floated and separated as much as possible. It is better to let them do it. The number of inclusions can be adjusted in this way by the operation in the steelmaking stage, and the method will be obvious to those skilled in the art.

Further, with respect to elements such as S and N, for example, desulfurization efficiency is improved by adding desulfurization flux, or the pickup of N from the atmosphere is reduced after the components are adjusted by a vacuum theory gas device. It is better to reduce it by taking measures. Particularly when Ca is added or when a large amount of Al or Mn is added to coarsen the precipitate, it is important to reduce S, N, O and the like.

The heating temperature for hot rolling may be in the range of 1100 ° C to 1250 ° C, and the finish rolling temperature for hot rolling is 730 to 900 ° C.
The winding temperature is preferably in the range of 600 to 730 ° C. Further, hot-rolled sheet annealing after hot rolling may be performed, but it is not essential. Next, after one cold rolling or two or more cold rollings sandwiching an intermediate annealing to obtain a predetermined plate thickness, finish annealing is performed.

Further, an organic / inorganic mixed coating may be applied for the purpose of improving punchability and insulating properties. In this case, it is preferable that the film thickness is thin. A preferable range is 0.5 μm or less.

[0053]

Example: Molten steel blown in a converter is degassed and cast into a predetermined composition, and then a slab is heated to 1150 ° C. and hot-rolled to a plate thickness of 2.0 mm, and wound at 680 ° C. , Pickled. For steel containing 1% or more of Si, hot-rolled sheet annealing was performed at 860 ° C for 3 hours. Then, after cold rolling to a plate thickness of 0.5 mm, the temperature is 740 ° C in an atmosphere of 10% H ₂ -90% N _2.
Finish annealing was performed at 950 ° C for 35 to 60 seconds.

The finished steel sheet after annealing is slit to a width of 100 mm.
After making the hoop, the 20 discs were punched out and automatically crimped to prepare a crimped sample. The shape of the crimped portion at this time was a flat V shape. The binding force of the caulked portion was obtained by fixing the laminated core to a jig with an adhesive and performing a tensile test, and measuring the peel strength. Also, width 1.5 mm,
200 cores each with four 4 mm crimped parts
Individual pieces were produced and the crimpability was evaluated. The core shape and weight were 110 mm in outer dimensions, 180 sheets of laminated steel plates, and weight was about 3.5 kg. The crimping property is evaluated on a three-level scale. When the core is not pushed out at all when the pushing amount is 1 sheet, the pushing amount can be adjusted up to 2 sheets, and the core can be prevented from being pulled. In each case, it was marked with ◯, and when one or more pieces were scattered even if the pushing amount was adjusted, it was marked with x.

Table 2 shows the chemical composition of the steel sheet, the size and amount of inclusions in the steel, the peel strength of the crimped portion, and the crimpability evaluation results. In the present invention example (steel plate No. A to K) controlled to
It can be seen that the peeling strength of the crimped portion is high and the crimpability is excellent.

On the other hand, the steel plates No. L to O are inferior in the caulking property because the size, amount and composition of inclusions are within the scope of the present invention.

[0057]

[Table 2]

[0058]

As described above, according to the present invention, since a steel sheet having excellent caulking property can be obtained, productivity is improved on the user side by reducing caulking defects, and the caulking portion can be reduced in diameter and number. The reduction can contribute to downsizing of motors and improvement of core characteristics.

[Brief description of drawings]

FIG. 1 is a schematic view (flat V shape) of a caulking portion used for experiments and the like in the present invention.

FIG. 2 is a diagram showing the relationship between the number of inclusions in steel and the peel strength of the crimped portion.

FIG. 3 is a diagram showing the relationship between the number of inclusions in steel and the peel strength of the caulked portion.

FIG. 4 is a diagram showing the relationship between the number of inclusions in steel and the peel strength of the caulked portion.

FIG. 5 is a diagram showing the relationship between the Mg content and the peel strength of the crimped portion.

FIG. 6 is a diagram showing the relationship between the peel strength of the caulked portion of Ca-added steel and the S + O content.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasushi Tanaka             1-2-1, Marunouchi, Chiyoda-ku, Tokyo             Main Steel Pipe Co., Ltd. F-term (reference) 5E041 AA02 CA02 CA04 NN01 NN02

Claims (4)

[Claims] 1. In mass%, C: 0.005% or less, Si: 4% or less, so1.Al: 1.5% or less, Mn: 2% or less, P: 0.2% or less, S: 0.01% or less (including 0) ), N: 0.005% or less (including 0), O: 0.004% (including 0) or less,
Among the inclusions observed in the steel plate cross section, the balance being substantially Fe, and having a diameter of 1.5 to 5 μm, 40 pieces / mm ² or less,
A non-oriented electrical steel sheet with excellent crimpability, characterized by having a diameter of 5 μm or more of 2 pieces / mm ² or less. 2. In mass%, C: 0.005% or less, Si: 4% or less, so1.Al: 1.5% or less, Mn: 2% or less, P: 0.2% or less, S: 0.01% or less (including 0) ), N: 0.005% or less (including 0), O: 0.004% or less (including 0),
The balance consists essentially of Fe, and among the inclusions observed in the steel plate cross section with a diameter of 0.2 to 0.6 μm, 250 to 1500 pieces / m
A non-oriented electrical steel sheet having excellent caulking properties, characterized in that it has m ² and a diameter of 1.5 to 5 μm of 40 pieces / mm ² or less and a diameter of 5 μm or more of 2 pieces / mm ² or less. 3. The non-oriented electrical steel sheet having excellent crimpability according to claim 1, wherein the content of Mg is 0.0001 to 0.0020% in mass%. 4. The mass% includes Ca: 0.0001 to 0.004%, and further, the total sum of S and O is 0.005% or less, and any one of claims 1 to 3 is included. Non-oriented electrical steel sheet with excellent crimpability.