JPH0477067B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is used as an iron core material for electrical equipment.
The present invention relates to a non-oriented electrical steel sheet with low core loss and excellent magnetic flux density, and a method for manufacturing the same. [Conventional technology] In recent years, increasing the efficiency of electrical equipment has become a global power
There is a strong demand for this in the movement to save energy. For this reason, there is an increasing demand for non-oriented electrical steel sheets, which are widely used as iron core materials for motors and small and medium-sized transformers, to maintain high magnetic flux density and have low iron loss. . In conventional non-oriented electrical steel sheets, a method of increasing the content of Si or Al has generally been used as a means to reduce iron loss from the viewpoint of reducing eddy current loss due to increased specific resistance. However, this method has the problem that the magnetic flux density decreases. In addition to simply increasing the content of Si or Al, it is also possible to take component measures such as reducing C, reducing S, or adding B as described in JP-A-58-151453. Manufacturing process measures have been taken, such as increasing the annealing temperature and increasing the cold rolling reduction before final annealing, but even though these methods reduce iron loss, they do not significantly reduce magnetic flux density. This method was ineffective and could not meet the demand for producing a non-oriented electrical steel sheet with low iron loss and excellent magnetic flux density. [Problems to be Solved by the Invention] In view of the above, the present invention provides a non-oriented electrical steel sheet with low iron loss and high magnetic flux density, and a method for manufacturing the same. [Means for Solving the Problems] The present inventors actively utilize trace additive elements to develop the texture into [100] and [110] textures that are desirable for magnetic properties, and to improve magnetic properties. We have conducted extensive research with the aim of obtaining non-oriented electrical steel sheets with low iron loss and high magnetic flux density by suppressing the [111] texture, which is unfavorable for properties. As a result, they discovered that by simultaneously containing a small amount of Sn and Cu in steel, iron loss can be lowered and magnetic flux density can be increased. The present invention was made based on this knowledge, and the gist thereof is: C: 0.010% or less in weight%;
Si: 0.1% or more, 2.0% or less, Mn: 0.75% or more,
1.5% or less, Sn: 0.02% or more, 0.20% or less, Cu:
0.1% or more, 1.0% or less, S: 0.005% or less, acid-soluble Al: 0.005% or more, 0.1% or less, N: 0.007% or less, B: 0.005% or less, and the weight ratio with N is B/N.
The non-oriented electrical steel sheet has a low iron loss and excellent magnetic flux density, with the balance being Fe and unavoidable impurity elements. Another gist is that after hot rolling, the steel containing the above components is rolled and self-annealed at a temperature of 750°C or higher and 850°C or lower, or after hot rolling, it is hot rolled at a temperature of 750°C or higher and 850°C or lower. Board annealing,
Then, it is cold rolled once or twice or more with intermediate annealing in between, and then continuously annealed. Yet another gist is that after the continuous annealing of the cold rolled sheet, skin pass rolling is performed at a rolling reduction of 2 to 12%. The present invention will be explained in detail below. First, the reasons for limiting the steel components of the present invention will be discussed. C is a harmful component that increases core loss and causes magnetic aging, so it should be kept at 0.010% or less. As is well known, Si is a component that has the effect of reducing iron loss, and in order to achieve this effect, 0.1%
It is necessary to contain the above amount. On the other hand, as the content increases, the magnetic flux density decreases as mentioned above, rolling workability deteriorates, and costs increase.
2.0% or less. Al is a necessary component for deoxidation, but for this effect it must be contained at 0.005% or more. In addition, if it exceeds 0.1%, the deoxidizing effect will be saturated, so
Should be 0.1% or less. However, in this case, AlN
Since magnetism deteriorates due to the formation of B, B is added.
It is necessary to generate BN and suppress the generation of AlN. For this purpose, a B/N ratio of 0.5 to 1.5 is most effective. In addition, the absolute content of B is set to 0.005% or less in order to prevent the occurrence of cracks in the steel billet. Further, the absolute content of N is also set to 0.007% or less in order to prevent the formation of AlN, which is harmful to magnetism. Conventionally, Mn has not been used to improve the magnetic properties of non-oriented electrical steel sheets because it easily forms nonmetallic inclusions such as sulfides, but with the development of high-purity steel manufacturing technology, its use has become possible. It became. According to the findings of the present inventors, Mn has the effect of developing [100] and [110] textures that are desirable for magnetic properties, and suppressing [111] textures that are unfavorable for magnetic properties. The Mn content needs to be 0.75% or more to bring about this effect, as proposed in JP-A-58-117828. In addition, Mn lowers the ferrite-austenite transformation temperature, so if the Mn content exceeds 1.5%, ferrite-austenite transformation occurs during hot-rolled sheet annealing.
The texture improvement effect of Mn decreases. Therefore,
The Mn content was set to 0.75% or more and 1.5% or less. S generates nonmetallic inclusions such as MnS that are harmful to magnetism, so it needs to be kept at 0.005% or less.
In particular, containing 0.75 to 1.5% Mn lowers the ferrite-austenite transformation temperature, so it is necessary to perform sufficient recrystallization at a relatively low temperature, but for this purpose, the S content is low. It is effective to do so. By containing Sn in combination with Cc, iron loss is lowered,
It also has the effect of increasing magnetic flux density, but in order to exhibit this effect, it is necessary to contain it at 0.02% or more. On the other hand, even if its content increases, its effect will be saturated, and it will have adverse effects such as suppressing grain growth.
It also increases costs, so it is set at 0.20% or less. Cu has the effect of lowering core loss and increasing magnetic flux density due to its combined content with Sn, but in order to exhibit this effect, it is necessary to contain 0.1% or more. On the other hand, even if this content increases, it may cause problems such as hot embrittlement and workability and processability.
1.0% or less. Components other than those mentioned above are iron and unavoidable impurity elements. Next, the combined effect of Sn and Cu, which is a feature of the present invention, will be explained. Figure 1 shows a slab of steel with the composition shown in Table 1 that was hot-rolled, coiled at a temperature of 830°C, self-annealed, then cold-rolled to a thickness of 0.47mm.
These are the results of continuous finish annealing at a temperature of 790°C for 40 seconds, then cutting into Epstein samples, strain relief annealing at 790°C for 1 hour, and measuring magnetic properties. Compared to steel containing neither Sn nor Cu, steel containing only Sn and steel containing only Cu are found to have lower iron loss. However, steel containing a composite of Sn and Cu has an even lower core loss than steel and steel.
The effect of reducing iron loss is much greater than that of simply adding the effect of copper alone and the effect of copper alone. Moreover, the magnetic flux density can also be increased. In other words, in the case of steel containing only Cu, the magnetic flux density decreases slightly, whereas in steel with a composite content of Sn and Cu, steel containing neither Sn nor Cu and steel containing only Sn The magnetic flux density is further increased, and the combined effect of Sn and Cu is clear.

[Effect]

Next, the manufacturing method of the present invention will be explained. Steel made of the above-mentioned components is melted in a converter or electric furnace, and is made into a slab by continuous casting or ingot-forming and then blooming rolling. Next, it is hot rolled, but in this hot rolling, after hot rolling, it is rolled up at a temperature of 750°C or higher,
Self-annealing is performed using the heat possessed by the hot-rolled coil. During this self-annealing, it is convenient to cover the hot-rolled coil with a protective cover that prevents radiation of heat. in this case,
When the winding temperature is less than 750°C, the combined effect of Sn and Cu is small, and the effect of lowering iron loss and increasing magnetic flux density is small. Furthermore, since it contains 0.75 to 1.5% Mn, the effect tends to disappear due to ferrite-austenite transformation at temperatures above 850°C. In addition, in hot rolling, instead of rolling and self-annealing at a temperature of 750℃ or higher, after hot rolling,
Hot-rolled sheets are annealed at a temperature of 750℃ or higher and 850℃ or lower. Even with this, iron loss can be lowered and magnetic flux density can be increased due to the combined effect of Sn and Cu, but the effect is small when the hot-rolled sheet annealing temperature is less than 750°C.
Furthermore, by containing 0.75 to 1.5% of Mn, ferrite-austenite transformation occurs at temperatures above 850°C, and the effect tends to disappear. Next, the sheet is cold rolled once or twice or more with intermediate annealing in between to obtain a predetermined thickness. Next, continuous finish annealing is performed at a temperature below the ferrite-austenite transformation temperature for recrystallization and grain growth. As described above, a non-oriented electrical steel sheet is manufactured.Next, a so-called semi-process type non-oriented electrical steel sheet is subjected to a skin pass at a reduction rate of 2 to 12%, punched into a predetermined shape, and then subjected to strain relief annealing. is manufactured. The reason why the reduction ratio in skin pass rolling is set to 2 to 12% is that if it is less than 2%, it is difficult to improve the magnetic properties during strain relief annealing, and the reason why the upper limit is set to 12% is that if it exceeds this, the magnetic properties will deteriorate. This is because it deteriorates. [Example] Next, an example of the present invention will be shown. Example 1 Steel having the composition shown in Table 2 was manufactured under the processing conditions shown in the same table, cut into Epstein samples, and 790
Strain relief annealing was performed for 1 hour at ℃, and the magnetic properties were measured. The measurement results are also shown in the same table. It is clear that according to the present invention, it is possible to manufacture a non-oriented electrical steel sheet with extremely low iron loss and high magnetic flux density.

【table】

[Table] Example 2 Steel No. 11, 12, 13, 14, 15 used in Example 1 above
was cold rolled to a thickness of 0.50 mm, continuously annealed at 825°C for 60 seconds, and then subjected to skin pass rolling at a reduction rate of 6% to a thickness of 0.47 mm. After that, it was cut into Epstein samples and subjected to strain relief annealing at 790°C for 1 hour.
The magnetic properties were measured. The measurement results are shown in Table 3. It is clear that according to the present invention, it is possible to manufacture a non-oriented electrical steel sheet with extremely low iron loss and high magnetic flux density.

[Table] [Effects of the Invention] As described above, according to the present invention, a non-oriented electrical steel sheet with low iron loss and high magnetic flux density can be obtained, and with the increasing efficiency of electrical equipment, it has become popular as a core material for electrical equipment. It can fully meet the requirements for the non-oriented electrical steel sheets used, and its industrial effects are extremely large.

[Brief explanation of the drawing]

Figure 1 shows the iron loss of comparative materials and the present invention material.
FIG. 3 is a diagram showing the relationship between W _15/50 and magnetic flux density B ₅₀ .

Claims (1)

[Claims] 1% by weight, C: 0.010% or less, Si: 0.1% or more,
2.0% or less, Mn: 0.75% or more, 1.5% or less, Sn:
0.02% or more, 0.20% or less, Cu: 0.1% or more, 1.0%
Below, S: 0.005% or less, acid-soluble Al: 0.005% or more and 0.1% or less, N: 0.007% or less, B: 0.005% or less, and the weight ratio B/N with N is 0.5 to 1.5, and the balance is Non-oriented electrical steel sheet with low iron loss and excellent magnetic flux density, consisting of Fe and unavoidable impurity elements. 2 In weight%, C: 0.010% or less, Si: 0.1% or more,
2.0% or less, Mn: 0.75% or more, 1.5% or less, Sn:
0.02% or more, 0.20% or less, Cu: 0.1% or more, 1.0%
Below, S: 0.005% or less, acid-soluble Al: 0.005% or more and 0.1% or less, N: 0.007% or less, B: 0.005% or less, and the weight ratio B/N with N is 0.5 to 1.5, and the balance is After hot rolling, steel consisting of Fe and unavoidable impurity elements is rolled at a temperature of 750°C or higher and 850°C or lower, self-annealed, and then cold-rolled once or twice or more with intermediate annealing in between. A method for producing a non-oriented electrical steel sheet with low iron loss and excellent magnetic flux density, which comprises annealing. 3 C: 0.010% or less, Si: 0.1% or more in weight%,
2.0% or less, Mn: 0.75% or more, 1.5% or less, Sn:
0.02% or more, 0.20% or less, Cu: 0.1% or more, 1.0%
Below, S: 0.005% or less, acid-soluble Al: 0.005% or more and 0.1% or less, N: 0.007% or less, B: 0.005% or less, and the weight ratio B/N with N is 0.5 to 1.5, and the balance is After hot rolling, steel consisting of Fe and unavoidable impurity elements is rolled at a temperature of 750°C or higher and 850°C or lower, self-annealed, and then cold-rolled once or twice or more with intermediate annealing in between. A method for producing a non-oriented electrical steel sheet with low core loss and excellent magnetic flux density, which comprises skin pass rolling at a rolling reduction of 2 to 12% after annealing. 4 In weight%, C: 0.010% or less, Si: 0.1% or more,
2.0% or less, Mn: 0.75% or more, 1.5% or less, Sn:
0.02% or more, 0.20% or less, Cu: 0.1% or more, 1.0%
Below, S: 0.005% or less, acid-soluble Al: 0.005% or more and 0.1% or less, N: 0.007% or less, B: 0.005% or less, and the weight ratio B/N with N is 0.5 to 1.5, and the balance is Steel consisting of Fe and unavoidable impurity elements is hot-rolled and then annealed at a temperature of 750°C or higher and 850°C or lower, then cold-rolled once or twice or more with an intermediate annealing in between, and then continuously annealed. A method for producing a non-oriented electrical steel sheet having low iron loss and excellent magnetic flux density. 5 In weight%, C: 0.010% or less, Si: 0.1% or more,
2.0% or less, Mn: 0.75% or more, 1.5% or less, Sn:
0.02% or more, 0.20% or less, Cu: 0.1% or more, 1.0%
Below, S: 0.005% or less, acid-soluble Al: 0.005% or more and 0.1% or less, N: 0.007% or less, B: 0.005% or less, and the weight ratio B/N with N is 0.5 to 1.5, and the balance is Steel consisting of Fe and unavoidable impurity elements is hot-rolled and then annealed at a temperature of 750°C or higher and 850°C or lower, then cold-rolled once or twice or more with an intermediate annealing in between, and then continuously annealed. After that, 2~
A method for producing a non-oriented electrical steel sheet with low iron loss and excellent magnetic flux density, which is characterized by skin pass rolling at a rolling reduction of 12%.