JP3012826B2 - Semi-process non-oriented electrical steel sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semi-process non-oriented electrical steel sheet, and more particularly, to laminating non-oriented electrical steel sheets punched into a predetermined shape to form a core body, and annealing the core body. And a non-oriented electrical steel sheet used in a semi-process type manufacturing method for improving magnetic properties.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for electric equipment to save energy and increase efficiency due to environmental and resource issues. Improvement of efficiency is the greatest demand for motors and transformers. For this purpose, it is necessary to reduce iron loss, copper loss, and mechanical loss, and a laminate of non-oriented electrical steel sheets is used as the core of such a motor or transformer.

[0003] This non-oriented electrical steel sheet is manufactured by subjecting a hot-rolled sheet adjusted to a predetermined chemical composition to cold rolling including one or more annealings. Non-oriented electrical steel sheets in the so-called high alloy field having a specific resistance of 35 Ω · m × 10 ⁻⁸ or more by adding Si, Al, P, Mn, etc.

A motor core is manufactured by punching a hoop of a non-oriented electrical steel sheet with a press in a predetermined shape in a state where a punching oil is applied, laminating a large number of them, and fixing them by caulking or welding. Further, heat treatment is performed to remove the attached punching oil, and thereafter, re-annealing is performed. The manufacturing method in which the core body is formed and then re-annealed is called a semi-process type manufacturing method, while the manufacturing method in which re-annealing is not performed after the core body is formed is called a full process type manufacturing method.

[0005] The purpose of annealing the core body is primarily to remove distortion generated at the time of punching, and at the same time, to promote the growth of crystal grains to improve the magnetic characteristics. This annealing is performed, for example, in Japanese Patent Application Laid-Open Nos.
As described in JP-A-39444, the heat treatment is performed under a non-oxidizing or reducing atmosphere at a soaking temperature of about 750 ° C. for about 2 hours.

[0006] In the conventional annealing of a motor core, the atmosphere in the furnace of the annealing furnace is set to a non-oxidizing or reducing atmosphere because the heat treatment for removing the punching oil adhered thereto is performed, and then the magnetic steel sheet is used during the annealing. The atmosphere gas used at this time is mainly a nitrogen gas and a mixture of a hydrogen gas and a CO gas.

[0007]

By the way, non-oriented electrical steel sheets as a material for a motor or transformer core not only improve the magnetic properties, but also improve the workability and the occurrence of defective products in the manufacture of the core. Stable performance to prevent this is required.
Specifically, it has appropriate hardness, good flatness, high toughness, good cutting property with a cutting tool, good punching property, and no sticking during annealing.

[0008] Among these, an appropriate hardness range can be obtained by recrystallization annealing after cold rolling, and the flatness can be practically reduced by cold rolling and subsequent recrystallization annealing. Flatness in a range that does not hinder can be obtained. In addition, the punching property and sticking can be controlled by coating baked on the surface of the electromagnetic steel sheet.

However, with respect to the toughness and the machinability, conventional non-oriented electrical steel sheets have not always achieved sufficient performance, and there is room for improvement. The toughness is
This is a characteristic related to punching of a core by an automatic caulking method. If the core is low in toughness, cracks occur in the caulked portion, resulting in a defective product. In addition, the machinability is a characteristic related to cutting the outer periphery of the rotor core with a lathe, and if the machinability is not good, the cut surface becomes uneven. Both the toughness and the machinability largely depend on the grain size range of the electrical steel sheet after recrystallization annealing. If the grain size is too large, the toughness and machinability decrease.

The problem to be solved by the present invention is to obtain a semi-process non-oriented electrical steel sheet which is excellent in properties required as a material of the core, particularly excellent in toughness and machinability.

[0011]

Means for Solving the Problems The present inventor has repeatedly studied on measures for improving the toughness and machinability of the above-mentioned magnetic steel sheet as a material of the core, and as a result, the conventional magnetic steel sheet has been cold-rolled. The particle size range recrystallized by subsequent annealing is 80
１５０150 μm, the improvement in toughness and machinability is not obtained in this crystal grain size range, and by making the crystal grain size smaller, it is possible to improve the toughness and machinability of the electrical steel sheet as the core material. I found it.

That is, the semi-processed non-oriented electrical steel sheet of the present invention is a non-oriented electrical steel sheet having an intrinsic resistance of 35 Ω · m × 10 ⁻⁸ or more by adding an element that does not hinder the growth of crystal grains during annealing. The crystal grain size range from 5 to 5 by recrystallization annealing.
It is characterized by being tempered to 50 μm. Here, as elements that do not hinder the growth of crystal grains during annealing, Si, Al,
Any one or more of P and Mn can be added in the steel making process.

The crystal grain size range after recrystallization annealing can achieve 5 to 50 μm by a proper combination of annealing temperature and time. In the case of continuous annealing, the temperature is 750-850 ° C,
A time of about 15 to 30 seconds, for example, 800 ° C. × 30 seconds,
Alternatively, continuous annealing at 850 ° C. for 15 seconds is suitable. Generally, the crystal grain size can be reduced by annealing at a low temperature for a short time.

The crystal grain size after recrystallization annealing is 5 to 50 μm.
By setting m, the toughness and machinability of the electromagnetic steel sheet as the core material can be improved. The smaller the crystal grain size after recrystallization annealing is, the better the toughness is. However, if the crystal grain size is less than 5 μm, recrystallization will be insufficient, so the lower limit is 5 μm. On the other hand, if the crystal grain size exceeds 50 μm, the core becomes brittle, and the rate at which the laminated core breaks during crimping and becomes a defective product increases sharply. Therefore, the upper limit is set to 50 μm, more preferably 20 μm or less.

The hardness, which is another characteristic of the magnetic steel sheet as the material of the core, is Hμv30 in the state after cold rolling.
0 or more, but subsequent recrystallization annealing, for example, 800 ° C.
If continuous annealing is performed for × 30 seconds, Hμ can be changed according to the composition of the steel sheet.
A hardness of about v150 to 200 is stably obtained.

As for flatness, good flatness can be obtained by continuous annealing at about 800 ° C. for about 30 seconds after cold rolling. Punching properties and sticking can be controlled by a coating that is conventionally baked on the surface of an electrical steel sheet.

As described above, the specific resistance is 35 Ω · m × 1
0 non-oriented electrical steel sheet workpiece in which the ^-8 above, by using a non-oriented electrical steel sheet tempering the grain size range 5~50μm by recrystallization annealing the material, Ya workability during punching The machinability during cutting is improved, and the occurrence of defective products is reduced. Furthermore, the magnetic properties are further improved by annealing the core body made of this magnetic steel sheet at a temperature at which the crystal grain size of the steel sheet grows to 100 to 200 μm.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on experimental examples. Table 1 is a table showing the chemical components (additional elements) of the non-oriented electrical steel sheet used in the experiment and the properties of the steel sheet after continuous annealing. It is a table showing characteristics. The manufacturing process of the steel sheet is steelmaking-hot rolling-annealing-pickling-cold rolling-
Continuous annealing. A1, B1, and C1 steel sheets are electromagnetic steel sheets according to the present invention in which continuous annealing conditions are lower in temperature and time than conventional steel sheets, and A2, B2, and C2 steel sheets are steel sheets annealed under conventional continuous annealing conditions (comparative examples). is there.

[0019]

[Table 1]

[0020]

[Table 2]

As is clear from Tables 1 and 2, the electrical steel sheets A1, B1 and C1 according to the present invention have a crystal grain size after annealing by continuous annealing at a lower temperature and a shorter time than before.
３０30 μm, and the magnetic properties of the steel sheet are high temperature,
Although slightly inferior to the steel sheets A2, B2, and C2 of the comparative examples that were annealed for a long time, there was no occurrence of defects at the time of manufacturing the core body, and the magnetic properties after annealing after processing into the core body were as follows:
It shows characteristics equivalent to those of the steel sheets A2, B2, and C2 of the comparative example. This means that running costs in continuous annealing of a steel sheet can be reduced by low-temperature, short-time annealing, which greatly contributes to a reduction in manufacturing cost of the steel sheet.

Further, by annealing the core body at a temperature of 800 ° C. or more, the crystal grain size range is 100 to 200 μm.
, And the iron loss (W15 / 50) after annealing was significantly lower than the iron loss of the steel plate as the material, and it was confirmed that the magnetic properties were significantly improved. Even in the case of a steel sheet containing (added) Al, a gas that does not cause a nitridation reaction with Al contained in the steel sheet is used as an atmosphere gas during annealing.
It was confirmed that the magnetic properties were improved by annealing at a temperature of 00 ° C. or more. In addition, even if it is a core body manufactured from the electromagnetic steel sheet according to the present invention, the annealing temperature is 800 ° C.
If it is less than 80, the effect of improving the magnetic properties is insufficient, and
Annealing at 0 ° C. or higher is preferred.

FIG. 1 shows the steel sheets A1 and B
1 and 1 are graphs showing the results for C1, and broken lines shown by broken lines in the figure indicate Al-containing (added) steel sheets A1 and A1.
The result of annealing using an atmosphere gas mainly composed of N at the time of annealing the core body manufactured from C1 is shown. As is clear from the figure, the core body manufactured from the steel sheet containing Al
When annealing in a gas mainly composed of
If the temperature exceeds 0 ° C., the effect of improving the magnetic properties decreases, and the temperature increases to 850 ° C.
If the annealing temperature exceeds 800 ° C., the effect of remarkably reducing iron loss can be obtained when annealing is performed in a gas that does not cause a nitriding reaction with Al.

[0024]

According to the present invention, a non-oriented electrical steel sheet having a specific resistance of 35 Ω · m × 10 ⁻⁸ or more and a non-oriented electrical steel sheet having a grain size range of 5 to 50 μm refined by recrystallization annealing are used for motors. And as a material for transformer cores,
The workability at the time of punching and the workability at the time of cutting are improved, and the occurrence of defective products is reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between an annealing temperature of a core body and iron loss.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-10-25554 (JP, A) JP-A-6-145796 (JP, A) JP-A-7-26326 (JP, A) JP-A-7-26 26327 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C22C 38/00 303 C21D 8/12 C22C 38/06 H01F 1/16

Claims (1)

(57) [Claims] 1. After forming a core body by punching,
No semi-process for core production annealing at a temperature of 0 ° C or more
Grain-oriented electrical steel sheet, any of Si, Al, P, Mn
Containing at least one element and having a specific resistance of 35Ω · m ×
10 ⁻⁸ or more and recrystallized by annealing after cold rolling.
A semi-process non-oriented electrical steel sheet, wherein the crystal grain size range is 5 to 50 μm.