JPS6393823A - Annealing method for high silicon iron plate - Google Patents

Abstract

PURPOSE:To produce a high silicon iron plate having excellent magnetic characteristic and stable product characteristics, by executing annealing under the specific condition in the process of producing the high silicon iron plate by melting high silicon iron alloy containing the specific quantity of Si. CONSTITUTION:After hot-rolling a slab obtd. by melting iron alloy containing 4.0-7.0wt% Si, the high silicon iron plate is produced by executing de-scaling treatment, meta-warm temp. rolling, degassing treatment, annealing and insulating film coating treatment, in order. In the annealing treatment in this production process, at first, the pre-annealing is executed under holding for 30min-10hr in the range of temp. 200-400 deg.C to the degreased rolled material. next, the box annealing is executed in the range of temp. 800-1,300 deg.C to the rolled material and its soaking time is executed for the time from 10min to less than 10hr. In this way, the magnetic characteristic of rolled material is remarkably improved.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method of annealing high-silicon iron plates.

[Conventional technology and its problems]

Because silicon iron plates have excellent soft magnetic properties, they have traditionally been used in large quantities as materials for electric power magnetic cores and rotating machines, but in recent years, silicon iron plates have been used in electrical applications such as transformers and single-rotation machines from the viewpoint of energy and resource conservation. There is a strong demand for greater efficiency and miniaturization of equipment,
Along with this, the silicon iron plate that is the material for the iron core is also required to have better soft magnetic properties and iron loss properties. It is known that the soft magnetic properties of this silicon iron plate improve with the addition amount of St, and in particular, it shows the highest permeability around 6.6wt%, and also has a high specific electrical resistance, which reduces iron loss. There is.

However, the silicon iron plate has a St content of 4. If it exceeds 0 wt%, workability deteriorates rapidly, and for this reason, it was conventionally considered impossible to manufacture high-silicon iron plates on an industrial scale by rolling methods (hot-cold rolling methods).

In contrast to such rolling methods, a method called the ultra-rapid solidification method has been researched and developed in recent years, but the high-silicon foil strips produced by this method have poor surface properties and surface flatness, and also have poor thickness and There are many problems in implementing it on an industrial scale, such as the board width being limited, productivity being poor, and production costs being high.

[Means to solve the problem]

Under these circumstances, the present inventors have determined that the Si content is 4.0w.
We have been studying methods for producing high-silicon steel sheets by rolling. As a result, it has been found that it is possible to manufacture high-silicon steel sheets by rolling by selecting hot rolling conditions and the like.

By the way, in order to obtain the excellent magnetic properties of this type of silicon iron plate, it is necessary to cause recrystallization by annealing, but manufacturing by rolling has traditionally been considered impossible. No studies have yet been made on the annealing conditions for high-silicon iron plates obtained by rolling.

In view of the current situation, the inventors of the present invention
As a result of studying annealing methods for t56Si iron plates, we have discovered annealing conditions that provide excellent magnetic properties.

That is, the present invention provides St: 4.0 to 7. After hot-rolling a high-silicon iron alloy slab containing 0wt silicon, a high-silicon iron plate is manufactured by sequentially performing descaling treatment, rolling, degreasing treatment, annealing, and insulation coating treatment, and in the annealing treatment, 2
This is a method of annealing a high-silicon iron plate, which is characterized by performing pre-annealing at a temperature of 00 to 400°C for 30 minutes to 10 hours, and then performing box annealing at a temperature of 800 to 1300°C.

Hereinafter, one aspect of the present invention will be explained in detail.

In the present invention, an iron alloy containing 4.0 to 7.0 wtfi of Si is produced. As mentioned above, St is an element effective in increasing specific electrical resistance, reducing eddy current loss, and lowering iron loss, and in the present invention, St: 4. The target is iron alloys with owt'1 or more. On the other hand, if the Si content exceeds 7.0 wt%, the magnetic properties will deteriorate, such as an increase in magnetostriction, a decrease in the magnetic flux density and the maximum permeability, and the workability will also deteriorate.

After the il-formed alloy is hot-rolled, it is subjected to a descaling treatment, and then semi-warm rolled (including cold rolled) in a temperature range of room temperature to 400°C.

Next, this rolled material is degreased and then annealed.

In this annealing treatment, the material is first held at a temperature between 200° C. and 400° C. 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 one recovery effect, and at temperatures above 400°C, the amount of recovery is too large and the magnetic properties deteriorates. The recovery referred to here is estimated to have the following effects on magnetic properties.

The cold rolled material has one of the main orientations of the rolling texture (
111) plane, and this crystal plane is said to be extremely harmful to magnetic properties. The nucleation and growth rate of recrystallization during annealing depends on the internal strain energy, so if this internal strain energy is released (recovered) under certain appropriate conditions, the nucleation rate of recrystallization during recrystallization annealing will increase. It is thought that this increases the density of crystal planes other than the (111) plane within the plate plane, which has a positive effect on the magnetic properties.

The rolled material pre-annealed at a relatively low temperature in this manner is box-annealed at a temperature of 800 to 1300°C to form a recrystallized structure. The soaking time is preferably from 10 minutes to 10 hours. In this final annealing, if the soaking temperature is less than 800°C, sufficient grain growth will not occur and predetermined magnetic properties will not be obtained. Further, annealing at an annealing temperature exceeding 1300° C. causes abnormal grain growth, making it impossible to obtain excellent magnetic properties.

The annealing temperature and soaking time here are selected depending on the application. That is, it should be determined based on the balance between iron loss at the frequency used, required soft magnetic properties, magnetostriction, etc., and annealing cost.

Figure 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 μ3 measured after main annealing and the maximum magnetic permeability measured after simple annealing. μ! It represents the ratio (μ3/μl). Here, simple annealing is performed at 100°C/hr without performing pre-annealing.
Recrystallization annealing is performed for the same time as the annealing in this application, and cooling is performed at the same rate. In FIG. 1, the area between two solid lines represents the effect of the present invention. This effect depends on the history factor of the pre-annealing process and the factor during annealing.

For example, when the humid rolling temperature is low, this effect becomes noticeable by increasing the pre-annealing temperature in the present invention or by increasing the pre-annealing time (lengthening the holding time).First The range in the figure is due to the pre-annealing temperature and time.
This is due to differences in recrystallization annealing time, temperature increase, and cooling rate conditions.

In the above pre-annealing, 1
If held for more than 0 hours, the characteristics will deteriorate, so this should be avoided. Figure 2 summarizes the relationship between the holding time of pre-annealing and the obtained magnetic properties, and the horizontal axis is the pre-annealing (
200° C. to 400° C.), and the vertical axis represents the magnetic properties with respect to the holding time as the relative maximum permeability when the holding time is 30 minutes as 1.

However, the recrystallization annealing temperature, time, and heating/cooling rate were all performed under the same conditions.

In the annealing of the present invention, there are no particular limitations on the temperature increase rate below 200° C. and above 400° C., and the cooling rate during the entire cycle, or it is preferable not to rapidly cool the material to avoid distortion.

Also, annealing should be performed in non-oxidizing or reducing conditions.

Although it is possible to use a protective atmosphere gas as the annealing atmosphere, in order to make the effect more pronounced, reducing gas or inert gas,
or a mixture of these gases. Note that annealing may be performed under vacuum conditions with a furnace pressure of 10 torr, and a remarkable effect can also be obtained by this.

After annealing, the high silicon iron plate is treated with an insulation coating.

This insulating film is formed to increase the glabellar resistance of high-silicon iron plates used in a laminated state.For example, after applying a mixture of silica and monobasic magnesium phosphate to the plate surface, baking is performed at 800℃. 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 thickness of 2 m, and then pickled and rolled to a thickness of 0.3 m at a temperature of 100°C. Rolled between lagoons. Thereafter, it was degreased and annealed by increasing the temperature to 1000 DEG C. in a nitrogen atmosphere through various thermal cycles as shown in FIGS. 3(a) to 3(e).

The maximum magnetic permeability and core loss of the sample thus obtained were measured. here.

The measurement was carried out using a ring-shaped sample (outer diameter 20fi, inner diameter 1O■). FIG. 4 shows the maximum magnetic permeability of the test material for each thermal cycle, and FIG. 5 also shows the iron loss.

In both figures, the vertical axes are the ratio μ2/μl of the maximum magnetic permeability after each thermal cycle and after simple annealing, and the iron loss (WI
The ratio W, /Wl of O/400) is shown.

However, the thermal cycle for simple annealing is shown in FIG. 3(e). In this way, from 200℃ to 400℃
It can be seen that excellent magnetic properties can be obtained by maintaining the temperature in a temperature range between 30 minutes and 10 hours.

・Example (2) An iron alloy slab having the composition shown in Table 2 was hot rolled to a thickness of 2 mm, and then pickled to a thickness of 0.3 +u at a temperature of 50°C. Rolled to. Thereafter, it was degreased and annealed by increasing the temperature to 1200 DEG C. in a hydrogen atmosphere through various thermal cycles as shown in FIGS. 6(a) to (e).

Regarding the samples obtained in this way.

The maximum permeability and iron loss were measured. Here, the measurement was performed using a ring-shaped sample (outer diameter 20 m, inner diameter 10 fi).

Figure 7 shows the maximum permeability for each thermal cycle;
The figure also shows iron loss. Here, the vertical axis shows the ratio W27w of the maximum magnetic permeability and the iron loss (WIQ/40@) after each thermal cycle and simple annealing, respectively. However, here, the thermal cycle of simple annealing is Figure 6(e)
The atmosphere is hydrogen as described above. Thus, it can be seen that excellent magnetic properties can be obtained by maintaining the temperature in the temperature range between 200° C. and 400° C. for 30 minutes or more and 10 hours or less.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to obtain a high-silicon iron plate with significantly improved magnetic properties and stable product characteristics with excellent magnetic properties.

[Brief explanation of the drawing]

Figure 1 shows the effect of annealing in the present invention. This is shown by the relationship between the annealing temperature during recrystallization annealing and magnetic properties. Figure 2 shows the effect of low-temperature annealing in the present invention.
This is shown by the relationship between the retention time of v8m and the obtained magnetic properties. FIGS. 3(a) to 3(e) show the thermal cycle used in Example (1). FIG. 4 shows the maximum magnetic permeability of each sample material in Example (1), and FIG. 5 similarly shows the iron loss. FIGS. 6(a) to 6(e) show the thermal cycle used in Example (2). FIG. 7 shows the maximum magnetic permeability of each sample material in Example (2), and FIG. 8 similarly shows the iron loss. Patent applicant Nippon Kokan Co., Ltd. Inventor Takashi 1) Yoshi -'X
9. Money: quality (OC) Q, eε return dullness (・C) j contemptuous concentration (0C) KO W2/Wl R2A (d) tiger dullness time (hr) 6I! 1 (e) Yodun Haruben (hr) November 17, 1986

Claims (1)

[Claims] (1) After hot rolling a high-silicon iron alloy slab containing Si: 4.0 to 7.0 wt%, it is sequentially subjected to descaling treatment, rolling, degreasing treatment, annealing, and insulation coating treatment. In producing high-silicon iron plates, the annealing treatment is performed at a temperature of 200 to 400°C for 30°C.
A method for annealing a high-silicon iron plate, which comprises performing pre-annealing for a period of minutes to 10 hours, and then box annealing at a temperature of 800 to 1300°C. (2) The method for annealing a high-silicon iron plate according to claim (1), characterized in that the heating is performed at 800 to 1300°C immediately after the pre-annealing.