JPS63227717A - Production of high-silicon steel sheet - Google Patents

Abstract

PURPOSE:To develop the title silicon steel sheet having excellent soft magnetic characteristic and permeability and a low iron loss by hot-rolling a high-silicon steel slab into a sheet having a fine unrecrystallized laminar structure, and the quasi-hot-rolling the sheet under specified conditions. CONSTITUTION:A high-silicon steel slab contg. 4.0-7.0wt.% Si is soaked at 1,180 deg.C, and hot-rolled into a hot-rolled coil having 2.5mm thickness. The hot- rolling finish temp. is controlled to 720-850 deg.C, winding is carried out at 550-650 deg.C, and an unrecrystallized laminar structure is imparted to perform the succeeding hot rolling at <=500 deg.C. The scale formed on the surface during hot rolling is then removed, and the sheet is quasi-hot-rolled in the temp. range from room temp. to 500 deg.C into a thin sheet having 0.5mm thickness. Heat treatment is carried out at 100-500 deg.C for 1sec-120min between the passes in the hot rolling. An annealing separation agent is then coated, the sheet is annealed at >=800 deg.C, and finally an insulating film is formed.

Description

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

[Conventional technology and its problems]

Conventionally, iron plates containing less than 4.0 wt% of silicon,
They are called oriented silicon steel sheets or non-oriented silicon steel sheets, and are mainly used in practical applications by being processed and formed into laminated iron cores and wound iron cores for various electromagnetic induction devices, and cases for electromagnetic shielding.

In recent years, there has been a strong demand for smaller and more efficient electromagnetic and electronic components from the viewpoint of resource and energy conservation, and materials with excellent soft magnetic properties, especially low iron loss and high magnetic permeability, have been required. Ta. It is known that in silicon-iron alloy systems, iron loss decreases as the silicon content increases, and that magnetic permeability reaches a maximum at around 6.5vt%, exhibiting excellent soft magnetic properties such as roughening magnetostriction becoming almost zero. ing. However, when the silicon content exceeds 4.0 wt%, the workability deteriorates significantly, and for this reason, it has been difficult to industrially manufacture the silicon by the conventional rolling method consisting of a combination of hot rolling and cold rolling. As a manufacturing method, there is only one method disclosed, for example, an ultra-rapid solidification method as shown in Japanese Patent Application Laid-Open No. 55-69223. However, the high-silicon foil strip produced by this ultra-rapid solidification method has inferior surface properties and surface flatness compared to rolled products, and it is difficult to manufacture wide and thick materials, making it difficult to manufacture electromagnetic and electronic components. There are many problems in putting it into practical use as a material.

Under these circumstances, the present inventors have determined that the silicon 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. That is, the present inventors have discovered that subsequent rolling becomes possible by forming a fine unrecrystallized layered structure through hot rolling. High-silicon steel sheets manufactured by this rolling method have excellent surface properties, so they have a high space factor when manufacturing laminated iron cores and wound iron cores, and thick materials can be easily manufactured, so they are used for electromagnetic and electronic components. It has extremely advantageous features such as being able to greatly simplify the assembly process.

Means for Solving Problem C] In order to manufacture such a high-silicon iron plate, the present inventors have devised a method that can effectively utilize the excellent magnetic properties inherent to the high-silicon iron alloy system. As a result of repeated studies, it was found that excellent magnetic properties can be obtained by cold or semi-warm rolling the hot rolled material and performing inter-pass recovery treatment during this rolling. .

That is, the present invention has a ratio of 81:4.0 to 7. Ovrt%
After hot rolling a high-silicon iron alloy slab to form a fine unrecrystallized layered structure, a high-silicon iron plate is manufactured by sequentially performing descaling, rolling, degreasing, annealing, and insulation coating. For this purpose, the above-mentioned rolling is carried out while keeping the plate temperature within the temperature range of room temperature to SOO℃, and 10
Its basic feature is that it is maintained at a temperature of 0 to 500°C for 1 second to 120 minutes.

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

The silicon iron plate targeted by the present invention has a silicon content of 4.0 to ? ,0
Contains wt%. As mentioned above, silicon is an effective element for increasing the specific electrical resistance, reducing eddy current loss, and lowering iron loss. If the silicon content is less than 4.0 wt%, iron loss is relatively high.

The soft magnetic properties of the maximum magnetic permeability are also not good.

On the other hand, if the silicon content exceeds 7.0 wt%, the magnetic properties will deteriorate, such as an increase in magnetostriction and a decrease in saturation magnetic flux density and maximum magnetic permeability, and workability will also deteriorate. For the above reasons, the silicon content is defined as 4.0 to 7.0 wt% in the present invention.

According to the method of the present invention, a silicon-iron alloy slab having such a silicon content is finally formed into a plate having a thickness of 5 to 1 inch by hot rolling. In this hot rolling, it is necessary to have a specific structure in order to enable subsequent rolling at 500° C. or lower. That is, such rolling at 500° C. or lower becomes possible only by forming a fine unrecrystallized layered structure by hot rolling.

The fineness of the structure is expressed by the average grain boundary spacing in the plate thickness direction, and in order to enable rolling, it is necessary to keep this below a critical value determined by the amount of St. This critical value is 1.90-0.2 fs x 81 (wt%) [ugly]
is given by The plate (strip) manufactured by hot rolling is
After descaling treatment is performed by means such as pickling or surface grinding, and further treatment such as slitting and trimming is performed as necessary, the sheet is rolled.

This rolling is semi-warm rolling, and is performed in a temperature range from room temperature to SOO°C (plate temperature). Humid rolling at temperatures above room temperature is performed on the entry side of the cold rolling mill (in the case of a reverse type, the exit side)
The entire strip or coil is heated by means such as a burner, radiation, or induction heating, and the temperature of the strip during rolling is maintained within a predetermined temperature range. Rollability is improved by performing such semi-warm rolling.

In the present invention, in such rolling, inter-pass recovery treatment,
That is, the strip is held within a predetermined temperature range for a predetermined time between passes, and this is a major feature of the present invention. FIGS. 1(1) to 1(,) show heat patterns for this inter-pass recovery process, and the inter-pass recovery process can be performed using any of these heat patterns. Among these, (a) is when heating and soaking treatment is performed between passes, (b) is when the soaking temperature between passes is equal to the rolling temperature, and (C) is when rolling is performed at a high temperature and equalized at a temperature lower than the rolling temperature. When heating is performed, (d) is a recovery process using the sensible heat of the strip during rolling without soaking, (e
) indicates the case where multiple passes are performed during cooling after heating.

The contents of the present invention will be described below based on experimental data. Figure 2 shows an IL48wt% silicon-iron alloy hot-rolled coil (thickness 2
．． 5. After cutting and pickling the average grain boundary spacing in the plate thickness direction of 80 μm, cold rolling including inter-pass recovery treatment was performed under various conditions described below to give an electrical circuit plate thickness of 0.5 m. The ring-shaped sample was then annealed for 1 hour in a hydrogen atmosphere, and the maximum magnetic permeability of the ring-shaped sample was measured. Here, the hot-rolled sheet after pickling is rolled by a reverse rolling mill, heated to a predetermined temperature in a heating device installed on the exit side, soaked for a predetermined time, and then cooled to room temperature. , which was cold-rolled again (corresponding to the heat pattern in Figure 1 (, )). Also, the inter-pass heating time means that the iron plate after rolling is 10
It means the time from when the temperature reaches 0°C to when the temperature drops to 100°C or less during cooling. By the way, for comparison! a (24℃)
Also, rolling was performed by leaving the iron plate for a predetermined time between passes.

From FIG. 2, it is clear that the maximum magnetic permeability is improved by performing heat treatment between passes. Furthermore, when looking at the heating temperature and time dependence of maximum magnetic permeability, there are conditions in which the maximum magnetic permeability is significantly improved when heating in a low temperature range for a long time, and when heating in a high temperature range on a short time side. I understand that. Although the mechanism for improving maximum magnetic permeability is not necessarily clear, the strain introduced into the structure during rolling is moderately released by the subsequent low-temperature heat treatment, and this strain introduction and moderate strain release are repeated. Through this process, the texture of the final product changed, and as a result, it is presumed that the soft magnetic properties were improved. Based on this idea, in the present invention, this heat treatment is referred to as inter-pass recovery treatment.

As mentioned above, when high-silicon iron is semi-warm rolled, it is known that the rolling properties are further improved as the sheet temperature during rolling increases. Therefore, we investigated the effect of interpass recovery treatment when the rolling temperature was increased. Figure 3 shows the inter-pass recovery temperature (=
(rolling temperature) dependence.

Here, the hot-rolled sheet after pickling is heated to a predetermined rolling temperature in a heating device installed on the entry side of a reverse or tandem rolling mill, and then rolled for 1 second in a heating device on the exit side of the rolling mill. It was heated to a temperature equal to the rolling temperature for 10 minutes and 120 minutes, soaked, and then re-rolled. Then, the hot-rolled sheet heated to a predetermined temperature was repeatedly subjected to the steps of rolling, heating, and soaking to obtain the final sheet thickness (1st r!g).
(corresponds to the heat pattern of J(b)). Note that here, the inter-pass recovery time of 1 second indicates the case of semi-warm rolling using a tandem mill. For comparison, the iron plate was left for a predetermined period of time between passes and rolled at room temperature (24°C). From Figure 3, the path is open and the temperature is back! ! It can be seen that the maximum magnetic permeability improves as t (rolling temperature) increases, and becomes almost constant at temperatures of 150° C. or higher. Looking more closely, the effect of improving the maximum magnetic permeability can be seen even in the low temperature range of about 50°C in Zoo-1i. The effect of time is significant here, with the longer the interpass recovery time, the higher the maximum permeability obtained.

Figure 4 shows the inter-pass recovery process (
300°C).

From this figure, the effect of improving the maximum magnetic permeability is recognized in the rolling temperature range from room temperature to 500°C.

Note that since the release of the strain introduced during rolling also occurs during cooling after rolling, the heat patterns shown in FIGS. 1(,) to (18) also have the effect of improving the maximum magnetic permeability.

Next, the reasons for the limitations of the present invention will be explained in detail. First, the rolling temperature is limited to 500°C or less, preferably 400°C or less, in order to avoid surface oxidation during rolling and to ensure accuracy of the plate thickness profile, although rolling properties are improved at higher temperatures. . Also, the lower limit is room temperature.

Next, regarding the inter-pass recovery processing condition 1ζ, the lower limit was set to 100° C. and 1 second because improvement in the soft magnetic properties was observed even under the conditions of 100° C. and 1 second in FIG. Also, regarding the upper limit of recovery processing time, it is more than 120 minutes.
Since long-term processing reduces work efficiency and increases manufacturing costs, the upper limit of the recovery processing temperature is 500°C to prevent excessive oxidation during heating, as mentioned above.
Hereinafter, the temperature is preferably limited to 400°C or less.

Note that, as shown in FIG. 3, it is desirable to lengthen the treatment time when performing the inter-pass recovery treatment at a low temperature, and to shorten it when performing the interpass recovery treatment at a high temperature, in order to improve soft magnetism.

Furthermore, when carrying out the present invention, the rolling temperature and the interpass recovery temperature may vary during a series of rolling steps as long as they are within the range defined by the present invention. Therefore, for example, heating equipment may be installed on the entry side of a tandem rolling mill and between the stands if necessary to perform a series of rolling, or the strip may be heated at the entry side of the rolling mill and semi-warm rolled at a predetermined temperature. It is also possible to immediately wind the coil, allow it to slowly cool for a certain period of time, and then repeat heating and rolling again.

The high-silicon steel plate whose final thickness was obtained by rolling as described above is
After being coated with an annealing separator if necessary, it is annealed at a temperature of 800° C. or higher, further coated with an insulating film, and then subjected to a baking treatment if necessary.

〔Example〕

Example (1) 0.0028wt%C-6,48wt%81 -0.0
A high-silicon iron alloy having a composition of 8 wt% was melted in a vacuum melting furnace and then cast to form an ingot. This ingot was soaked at 1180° C. for 3 hours, then bloomed into a slab, soaked again at 1180° C. for 1 hour, and made into a hot-rolled coil with a plate thickness of 2.5 mm using a hot rolling mill. At this time, the hot rolling finishing temperature is 850 to 720℃ 2 The coiling temperature is 6150 to 550℃
The average grain boundary spacing in the plate thickness direction of the obtained hot rolled coil was 40 pm. After pickling, this hot-rolled coil was divided by a slitter line and semi-warm rolled by a reverse type cold rolling mill equipped with heating equipment on the exit side under the conditions shown in Table 1.

The target plate thickness was set at 0.5-.

Table 1 Next, these coils were heated for 12 hours in a hydrogen gas atmosphere.
After annealing at 00°C for 1 hour, a sample was taken from the center of the coil, flattening annealing was performed at SOO°C, and a ring-shaped sample for magnetic measurement was punched from the center in the width direction, and its soft magnetic property was investigated. The results are shown in Table 2.

Example (2) High-silicon iron hot-rolled plate having the composition shown in Table 3 (thickness: 2.0 mm, average grain boundary spacing in the thickness direction: 6:500.#m).

b: 310 pm, c: 16011 m * d
: 60 μm), then cold rolling (rolling temperature 25°C) including interpass recovery treatment (every 1 pass) at 350°C for 5 minutes.
) to obtain a rolled plate with a thickness of 0.3.

For comparison, a cold rolled plate without interpass recovery treatment was also produced.

Samples were cut from the center of these coils, and after applying a StO-based annealing separator to the surface, they were annealed at 1180'CX for 3 hours in a vacuum annealing furnace at 5 x 10 Torr.

Furthermore, there are 20 outer diameters from the center in the width direction.

After punching out a ring-shaped magnetic measurement sample with an inner diameter of 10cm,
The DC magnetic properties were measured. The results are shown in Table 4.

Table 4: Invention method = Cold rolling including interpass recovery treatment at 350°C for 5 minutes Comparative method 2 Conventional cold rolling

[Brief explanation of the drawing]

FIGS. 1(,) to (,) illustrate heat patterns that can be adopted in the present invention. FIG. 2 shows the influence of the interpass recovery temperature (rolling temperature: room temperature) of a high-silicon iron plate on the magnetic properties obtained after final annealing. FIG. 3 shows the influence of the interpass recovery temperature (=rolling temperature) of a high-silicon iron plate on the magnetic properties obtained after final annealing. FIG. 4 shows the effect of inter-pass recovery treatment on a high-silicon iron plate in terms of the relationship between rolling temperature and magnetic properties.

Claims (1)

[Claims] After hot rolling a high-silicon iron alloy slab containing Si: 4.0 to 7.0 wt% to form a fine unrecrystallized layered structure, descaling, rolling, degreasing, and annealing. In producing a high-silicon iron plate by sequentially applying and insulating film treatment, the above-mentioned rolling is semi-warm rolling performed by keeping the plate temperature in the temperature range of room temperature to 500°C, and the rolling process is carried out at 100 to 500°C between rolling passes. 1 second to 120℃ temperature
A method for manufacturing a high-silicon iron plate, which is characterized by maintaining a high silicon content.