JPH0643612B2 - Method for manufacturing high silicon iron plate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a non-oriented high silicon iron plate.

[Prior Art and its Problems] Silicon iron plates have been used in large quantities as magnetic cores for electric power and materials for rotating machines because of their excellent soft magnetic properties. Strongly demands for efficiency and miniaturization of electrical equipment such as transformers and rotating machines.
Along with this, the silicon iron plate, which is a material for the iron core, is required to have more excellent soft magnetic characteristics and iron loss characteristics. It is known that the soft magnetic properties of this silicon iron plate improve with the addition amount of Si, and show the highest magnetic permeability especially near 6.5 wt%, and further, the specific electric resistance is high, so that the iron loss is also small.

However, the workability of the silicon iron plate deteriorates sharply when the Si content is 4.0 wt% or more.
It has been considered impossible to produce a high-silicon iron plate on an industrial scale by the cold rolling method).

In contrast to such a rolling method, a method called an ultra-rapid solidification method has been researched and developed in recent years, but the high silicon foil strip produced by this method is inferior in surface properties and surface flatness, and has a thickness The plate width is limited, and in addition, productivity is inferior and production costs are high, and there are many problems in carrying out on an industrial scale.

[Means for solving problems]

Under these circumstances, the present inventors have been studying a manufacturing method by rolling a high silicon iron plate having a Si content of 4.0 wt% or more. As a result, it has been found that it is possible to manufacture a high silicon iron sheet by rolling by selecting hot rolling conditions and the like. The present applicant has previously proposed Japanese Patent Application No. 60-5951 (Japanese Patent Application Laid-Open No. 61-166923) as one of the methods for producing a high silicon iron plate by such rolling. In this manufacturing method, an ingot or continuous cast slab of high-silicon steel is slab-rolled or rough-rolled under specific heating / rolling conditions to refine the crystal grains, and then continuously hot-rolled under specific conditions. This is a method for producing a high-silicon iron plate in which a hot-rolled sheet structure suitable for hot rolling is cold-rolled.

By the way, in order to obtain the excellent magnetic properties of this kind of silicon iron plate, it is necessary to anneal and recrystallize, but since the production itself by conventional rolling has been impossible, No study has been made on the annealing conditions of the high-silicon iron plate obtained by rolling.

In view of such a current situation, the present inventors have made 4.0-7.0 wt% Si
As a result of studying the annealing method of the iron plate, the inventors found the annealing conditions that can obtain excellent magnetic properties.

That is, according to the present invention, when a high silicon iron sheet is produced from a high silicon iron alloy slab containing Si: 4.0 to 7.0 wt% through hot rolling, quasi warm rolling, annealing and insulating film treatment, Warm rolling is performed at a temperature of room temperature to 400 ° C, and in the annealing treatment, pre-annealing is performed at a temperature of 200 to 400 ° C for 30 minutes to 10 hours, and then at a temperature of 800 to 1300 ° C for more than 10 minutes to 10 hours. The method for producing a non-oriented high-silicon iron plate is characterized by carrying out box annealing.

Hereinafter, the details of the present invention will be described.

In the present invention, an iron alloy containing 4.0 to 7.0 wt% Si is melted. As described above, Si is an element effective in increasing the specific electric resistance, reducing the eddy current loss, and reducing the iron loss.
In the present invention, the target is an iron alloy containing 4.0 wt% or more of Si. On the other hand, when Si exceeds 7.0 wt%, the magnetic characteristics rather deteriorate, such as an increase in magnetostriction, a decrease in saturation magnetic flux density and maximum magnetic permeability, and workability also deteriorates. The molten alloy is hot-rolled and, if necessary, descaled, then at room temperature to 40
Semi-warm rolling (including cold rolling) is performed in the temperature range of 00 ° C.

This semi-warm rolling temperature is basically defined by a temperature condition in which the structure does not recrystallize during rolling. Si: 4 to 7 wt%
Recrystallization occurs at temperatures above 500 ° C.
From this point of view, the quasi-warm rolling can be performed at room temperature or higher and 500 ° C. or lower. However, 400
When the quasi-warm rolling is performed at a temperature higher than ° C, the surface of the steel sheet is remarkably oxidized, and even if a descaling treatment is performed thereafter, it is difficult to remove the scale and the yield is reduced, which is not preferable. Therefore, in the present invention, the quasi-warm rolling at room temperature to 400 ° C is performed.

Next, this rolled material is subjected to a descaling treatment if necessary, and annealed after degreasing.

In this annealing process, first in the temperature range between 200 ℃ and 400 ℃.
Hold for 30 minutes to 10 hours. In the above temperature range, recrystallization does not occur and recovery occurs, but at temperatures below 200 ° C, it takes a long time to obtain the effect of recovery, and above 400 ° C, the recovery amount is too large and the magnetic properties are reversed. Deteriorates. The recovery here is presumed to have the following effects on the magnetic properties.

Quasi-warm rolled material is one of the main orientations of rolling texture {1
It has a {11} plane, and this crystal plane is said to be extremely harmful to magnetic properties. Since the nucleation of recrystallization and its growth rate during annealing depend on the internal energy saving, if the internal strain energy is released (recovered) under certain appropriate conditions, the plate will be recrystallized during annealing. In the plane (11
It is thought that it increases the density of crystal planes other than the 1} plane, and has a good effect on the magnetic properties.

In this way, the rolled material that has been pre-annealed at a relatively low temperature
Box annealing is performed at a temperature of 800 to 1300 ° C, and a recrystallized structure is formed. The soaking time is preferably over 10 minutes and within 10 hours. In this final annealing, if the soaking temperature is less than 800 ° C, grain growth does not sufficiently occur and the predetermined magnetic properties cannot be obtained. Further, annealing at an annealing temperature exceeding 1300 ° C causes abnormal grain growth, and excellent magnetic properties cannot be obtained.

The annealing temperature and soaking time here are selected depending on the application. That is, it should be determined in consideration of the iron loss at the frequency used, the required soft magnetic characteristics and magnetostriction, and the cost of annealing.

FIG. 1 shows the effect of annealing in the present invention, where the horizontal axis represents the annealing temperature during recrystallization annealing, and the vertical axis represents the maximum magnetic permeability μ ₂ measured after the annealing of the present application and the maximum permeability measured after simple annealing. It represents the ratio of magnetic susceptibility μ ₁ (μ ₂ / μ ₁ ). The simple annealing here is performed at a temperature rising rate of 100 ° C./hr without performing pre-annealing, and recrystallization annealing is performed for the same time as the annealing of the present application.
Cooling at the same speed. In FIG. 1, the effect between the two solid lines represents the effect of the present invention. This effect depends on the hysteresis factor in the pre-annealing process and the factor during annealing. For example, when the semi-warm rolling temperature is low, the effect becomes remarkable by increasing the pre-annealing temperature in the present invention or increasing the pre-annealing time (lengthening the holding time). The width of FIG. 1 varies depending on the pre-annealing temperature and time, the recrystallization annealing time, the temperature rise, and the cooling rate conditions.

In the above-mentioned pre-annealing, if the temperature is kept in the temperature range of 200 to 400 ° C. for more than 10 hours, the characteristics will be deteriorated and this should be avoided. Fig. 2 summarizes the relationship between the holding time of pre-annealing and the obtained magnetic properties. The horizontal axis shows pre-annealing (200 ℃ ~ 4
The holding time at 00 ° C) is shown, and the vertical axis shows the magnetic characteristics with respect to the holding time by the relative maximum magnetic permeability when the holding time is 30 minutes. However, the recrystallization annealing temperature, time, and temperature rising / cooling rate were all the same.

In the annealing of the present invention, the temperature rising rates of less than 200 ° C. and more than 400 ° C., and the cooling rate during the entire cycle are not particularly limited, but it is preferable not to perform rapid cooling so as to prevent distortion in cooling.

Also, the annealing should be performed in the non-oxidized or reduced state.
The annealing atmosphere can be a protective atmosphere gas, but in order to make the effect remarkable, a reducing gas or an inert gas,
Or it should be a mixed gas of these. The annealing may be performed under a vacuum condition in which the pressure inside the furnace is set to 10 ^-1 torr or less, and this also has a remarkable effect.

After annealing, the high silicon iron plate is treated with an insulating film. This insulating film is formed to increase the interlayer resistance of the high silicon iron plate used in the laminated state. For example, after applying a mixed solution of silica and dibasic magnesium phosphate to the plate surface, baking is performed at 800 ° C. The processing to be performed is performed.

〔Example〕

-Example (1) An iron alloy slab having the composition shown in Table 1 was hot-rolled to a plate thickness of 2 mm, and then a plate thickness of 0.3 mm at a plate temperature of 100 ° C.
Semi-warm rolling. Then, descaling and degreasing were performed, and the temperature was raised to 1000 ° C. and annealed in a nitrogen atmosphere by various heat cycles as shown in FIGS. 3 (a) to (e).

The maximum magnetic permeability and the iron loss of the sample thus obtained were measured. Here, the measurement is ring-shaped (outer diameter 20
mm, inner diameter 10 mm). FIG. 4 shows the maximum magnetic permeability of the test material for each heat cycle, and FIG. 5 also shows the core loss.

In both figures, the vertical axis represents the ratio of maximum permeability after each heat cycle and after simple annealing, μ ₂ / μ ₁ , and iron loss (W
The ratio W ₂ / W ₁ of _10/400 ) is shown.

However, the thermal cycle of simple annealing is shown in FIG. 3 (e). As described above, it is understood that excellent magnetic properties can be obtained by keeping the temperature range between 200 ° C. and 400 ° C. for 30 minutes or more and 10 hours or less.

-Example (2) An iron alloy slab having the composition shown in Table 2 was hot-rolled to a plate thickness of 2 mm, and then rolled to a plate thickness of 0.3 mm at a plate temperature of 50 ° C. After that, descaling and degreasing were performed, and in a hydrogen atmosphere, the temperature was raised to 1200 ° C. by various heat cycles as shown in FIGS. 6 (a) to 6 (e), and annealing was performed.

The maximum magnetic permeability and the iron loss of the sample thus obtained were measured. The measurement here is ring-shaped (outer diameter 20 m
m, inner diameter 10 mm). FIG. 7 shows the maximum magnetic permeability for each heat cycle, and FIG. 8 also shows the core loss. Here, the vertical axis represents the ratio of maximum permeability μ ₂ / μ ₁ after each heat cycle and after simple annealing, and the ratio W ₂ / W ₁ of iron loss (W _10/400 ). However, the thermal cycle of the simple annealing is as shown in FIG. 6 (e), and the atmosphere is hydrogen as described above. As described above, it is understood that excellent magnetic properties can be obtained by keeping the temperature range between 200 ° C. and 400 ° C. for 30 minutes or more and 10 hours or less.

[Effects of the Invention] As described above, according to the present invention, it is possible to obtain a non-oriented high silicon iron plate having significantly improved magnetic characteristics and excellent magnetic characteristics and stable product characteristics.

[Brief description of drawings]

FIG. 1 shows the effect of annealing in the present invention by the relationship between the annealing temperature and the magnetic characteristics during recrystallization annealing. FIG. 2 shows the effect of low temperature annealing in the present invention in relation to the holding time of low temperature annealing and the obtained magnetic characteristics. Fig. 3
(a)-(e) shows the thermal cycle used in Example (1). FIG. 4 shows the maximum magnetic permeability of each test material in Example (1), and FIG. 5 also shows the core loss. FIGS. 6 (a) to 6 (e) show the thermal cycle used in Example (2). FIG. 7 shows the maximum magnetic permeability of each test material in Example (2), and FIG. 8 also shows the core loss.

Claims (2)

[Claims] 1. A high silicon iron sheet is produced from a high silicon iron alloy slab containing Si: 4.0 to 7.0 wt% through hot rolling, semi-warm rolling, annealing and insulating coating treatment. Warm rolling is performed at a temperature of room temperature to 400 ° C., and in the annealing treatment, pre-annealing is performed at a temperature of 200 to 400 ° C. for 30 minutes to 10 hours,
Then, a method for producing a high-silicon iron plate, which comprises performing box annealing at a temperature of 800 to 1300 ° C. for more than 10 minutes to 10 hours. 2. The method for producing a high silicon iron plate according to claim 1, wherein the pre-annealing is immediately heated to 800 to 1300 ° C.