JPH0645823B2 - Method for manufacturing high silicon iron plate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a non-oriented high silicon iron plate having excellent soft magnetic properties.

[Conventional technology and its problems]

Conventionally, an iron plate containing less than 4.0 wt% of silicon is called a directional silicon steel plate or a non-oriented silicon steel plate depending on its manufacturing method, and is mainly used for laminated iron cores, wound iron cores, or electromagnetic shields for various electromagnetic induction devices. It is processed and molded into a case for use for practical use.

In recent years, there has been a strong demand for miniaturization and high efficiency of electromagnetic electronic components from the viewpoint of resource saving and energy saving, and a material having excellent soft magnetic properties, particularly low iron loss and high magnetic permeability, has been demanded. It was It is known that in a silicon-iron alloy system, as the silicon content increases, the iron loss decreases, and in addition, the magnetic permeability reaches a maximum around 6.5 wt% and the magnetostriction becomes almost zero, and it exhibits excellent soft magnetic properties. . However, when the content of silicon is 4.0 wt% or more, the workability is significantly deteriorated. Therefore, it is conventionally difficult to industrially manufacture by a rolling method including a combination of hot rolling and cold rolling. However, as the manufacturing method thereof, for example, only the ultra-rapid solidification method as disclosed in JP-A-55-69223 is disclosed. However, the high silicon foil strip produced by this ultra rapid solidification method is inferior in surface texture and surface flatness to rolled products, and it is difficult to produce wide and thick materials. There are many problems in practical application as a material.

[Means for solving problems]

Under these circumstances, the present inventors have found that the Si content is 4.0 wt%.
We have proceeded to study the manufacturing method by rolling the non-oriented high-silicon iron plate. 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. Since the high silicon iron plate manufactured by such a rolling method has excellent surface properties, it has a high space factor when manufacturing a laminated iron core, a wound iron core, etc. It has extremely advantageous features such as the assembly process can be greatly simplified.

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 considered that 4.0-7.0 wt% Si
As a result of investigating the annealing method for an iron plate, the inventors found the annealing conditions that can obtain excellent magnetic properties.

That is, the present invention provides a high silicon iron sheet from a high silicon iron alloy slab containing Si: 4.0 to 7.0 wt% through hot rolling, quasi-warm rolling at a sheet temperature of 400 ° C. or less, annealing and insulating coating treatment. In the production, in the annealing treatment, pre-annealing is performed at a temperature of 200 to 400 ° C. for 1 minute to 3 hours, and then final annealing is performed at a temperature of 800 to 1300 ° C. for 1 minute to 10 minutes. And a method for manufacturing a high silicon iron plate.

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

In the present invention, an iron alloy containing 4.0 to 7.0 wt% of Si is melted. As described above, Si is an element effective in increasing the specific electric resistance to reduce the eddy current loss and lowering the iron loss. In the present invention, the target is an iron alloy having Si: 4.0 wt% or more.
On the other hand, when Si exceeds 7.0 wt%, the magnetic characteristics are deteriorated due to the increase of magnetostriction, the decrease of saturation magnetic flux density and the maximum magnetic permeability, and the workability is deteriorated.

Note that it is also effective to reduce elements other than Si in order to further improve the magnetic characteristics. That is, C0.2%, Al
2%, Mn0.5%, P0.1%, (total amount of other impurities)
0.2%, preferably C0.01%, Al0.4%, Mn0.1%,
By setting P to 0.1% and (total amount of other impurities) to 0.05%, the magnetic characteristics can be further improved.

The melted alloy is hot-rolled and, if necessary, subjected to descaling treatment by means such as pickling or surface grinding. Next, the hot-rolled sheet is subjected to processing such as slitting and trimming, if necessary, and then subjected to quasi-warm rolling (including cold rolling) in a temperature range of room temperature to 400 ° C. This semi-warm rolling is
The strip or the entire coil to be passed is heated using a heating means such as burner radiation or induction heating, and rolling is performed while maintaining the hot rolled sheet at the above temperature. In this rolling, the plate temperature is 400
If the temperature exceeds ℃, it will be difficult to control the plate thickness profile in the coil width direction, and a thick oxide film will be formed on the strip surface, making it difficult to remove scale even if descaling treatment is performed thereafter. Therefore, the rolling temperature is limited to 400 ° C.

The high-silicon iron plate thus rolled to the final plate thickness is subjected to a descaling process if necessary, and is annealed to impart magnetic properties after the degreasing process. The present inventors, as a result of examining the relationship between the annealing characteristics and the magnetic characteristics to improve the magnetic characteristics of the high silicon iron plate, in the annealing step after the quasi-warm rolling, the strain is released first, It was found that recrystallization and grain growth occur subsequently, and that the texture after recrystallization changes when the conditions for recovering the strain are changed, which changes the soft magnetic properties of the high silicon iron plate. Based on such knowledge, the present invention is intended to dramatically improve the magnetic characteristics after annealing by performing pre-annealing in a relatively low temperature region before the final annealing at high temperature for a short time. That is, in the pre-annealing at a temperature of 200 to 400 ° C for 1 minute to
Hold for 3 hours, at a temperature of 800-1300 ℃ for 1 minute-10
The final annealing was performed for a minute.

Fig. 1 shows the relationship between the pre-annealing conditions of a silicon iron cold-rolled sheet and the magnetic properties of the annealed iron sheet. The sheet thickness of 0.50 mm was 6.48 wt%.
Annealing was performed on the silicon-iron cold-rolled sheet by the heat cycle shown in FIG. 2 to examine the magnetic characteristics. That is, pre-annealing for recovery is performed under various conditions shown in FIG. 2, followed by final annealing including heating in a hydrogen gas atmosphere up to 1200 ° C. and soaking for 10 minutes. To outer diameter 20 mm, inner diameter 10 mm
The ring was punched out and its maximum magnetic permeability was investigated.

From the figure, it is understood that the soft magnetic characteristics are improved by selecting an appropriate pre-annealing condition. That is, the pre-annealing temperature is
At 100 ° C, the strain is hardly released, and at 500 ° C, the strain is completely released, so the improvement effect cannot be obtained, and excellent magnetic characteristics are obtained in the range of 200 to 400 ° C. There is. Also in this temperature range, the effect is small if the pre-annealing soaking time is too short or too long, and excellent magnetic properties are obtained in 1 minute to 3 hours.

The pre-annealing may be performed off-line by using a continuous annealing line or a box-type annealing furnace, but it may be performed at low temperature in the preceding stage of the continuous annealing line (for example, pre-tropical zone) and immediately finished without cooling. Annealing may be performed, and this method can reduce the cost without damaging the magnetic properties. However, when the two-step annealing is performed as described above, the pre-annealing cannot be performed for a long time, so the annealing time is set to 1
From 10 minutes to 10 minutes.

In addition, since pre-annealing is intended to release strain,
If the conditions specified in the present invention are satisfied, means other than the above-mentioned annealing method can be adopted. For example, the magnetic properties can be improved if the above conditions are satisfied even if the material is wound immediately after the quasi-warm rolling and soaked in a heat insulation facility.

The high-silicon iron plate that has been pre-annealed at a relatively low temperature in this way is reheated to 800 to 1300 ° C.
Minute annealing (usually continuous annealing) is performed. In this final annealing, the processing temperature is less than 800 ℃, or the processing time is 1
If it is less than the minute, grain growth does not sufficiently occur and desired magnetic properties cannot be obtained. Further, it is industrially difficult to anneal at an annealing temperature exceeding 1300 ° C. Further, the longer the final annealing time is, the more preferable it is in terms of magnetic properties, but there is an industrial problem such that the length of the continuous annealing line is long and the equipment cost is high. Therefore, the upper limit of the soaking time is 10 minutes. Therefore, the final annealing of the present invention is
It is carried out by soaking at a temperature of 800 ° C to 1300 ° C for 1 to 10 minutes.

Such final annealing is usually a continuous annealing or a short-time annealing by plate-like annealing, which prevents seizure (adhesion) of the product due to high-temperature annealing in batch annealing such as box-type annealing, while maintaining soft magnetic properties. Can be improved.

The atmosphere during annealing may be a non-oxidizing atmosphere,
It can also be performed under vacuum.

After annealing, the high silicon iron plate is subjected to an insulating film treatment with an organic or inorganic coating material. 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) A high silicon iron alloy having a composition of 0.0028 wt% C-6.48 wt% Si-0.14 wt% Mn was melted in a vacuum melting furnace and then cast into an ingot.
After soaking this ingot at 1180 ℃ for 3 hours, slab rolling,
After making a slab having a thickness of 180 mm, it was soaked again at 1180 ° C. for 1 hour and hot rolled to obtain a hot rolled coil having a plate thickness of 2.5 mm. The hot rolled coil was pickled and cold rolled to obtain a cold pressed coil having a plate thickness of 0.50 mm.

Next, this coil was divided into four, and low temperature pre-annealing was performed in the box-type annealing furnace under the conditions shown in Table 1, followed by cooling and subsequent 1150
Continuous annealing including soaking for 3 minutes at ℃ was performed. The annealed small coil was flattened and annealed at 800 ° C, and a ring sample for magnetic measurement was punched out from the center of the sheet width, and the soft magnetic characteristics were investigated. The results are shown in Table 2.

-Example (2) After high-silicon iron hot-rolled sheet (sheet thickness 2.0 mm) having the composition shown in Table 3 was pickled, a reverse type cold rolling mill equipped with heating equipment on the inlet side was used, and 350 Semi-warm rolling including soaking for 5 minutes at ℃ for each pass is performed. A rolled plate having a plate thickness of 0.3 mm was used.

Next, these coils were divided, and some of them were placed in a box-type annealing furnace.
Pre-annealing was performed at 0 ° C. for 1 hour, and then continuous annealing including soaking for 5 minutes at 1180 ° C. was performed including the coil not subjected to pre-annealing.

After the ring-shaped magnetic measurement sample was punched from the center of the coil after annealing, the DC magnetic characteristics were measured. The results are shown in Table 4.

-Example (3) After high-silicon iron hot-rolled sheet (sheet thickness 2.0 mm) having the composition shown in Table 5 was pickled, a reverse type cold rolling mill equipped with heating equipment on the inlet side was used to obtain 300 Semi-warm rolling including soaking at ℃ × 1 minute for each pass is performed. A rolled plate having a plate thickness of 0.3 mm was used. Next, these coils were divided, and part of them was heated in a box-type annealing furnace at 250 ° C x 1
Pre-annealing was performed for a period of time, and then continuous annealing including soaking at 1200 ° C. for 2 minutes was performed including the coil not subjected to pre-annealing.

Collect the magnetic measurement sample from the center of the coil after annealing,
The DC magnetic properties were measured. The results are shown in Table 6. As is clear from the table, according to the present invention, more excellent magnetic characteristics can be obtained. Further, comparing the alloys a, b and c in Table 5, it can be seen that the effect of the present invention becomes more remarkable when the elements other than Fe and Si are small.

-Example (4) An insulating film agent made of colloidal silica monobasic magnesium phosphate and chromic anhydride was applied to the high silicon steel strip prepared in Example (3) and baked at 600 ° C. After baking, a magnetic measurement sample was taken from the center of the coil, and three sheets were laminated to measure the iron loss. The results are shown in Table 7. As is clear from the table, according to the present invention, a steel sheet having more excellent magnetic properties can be obtained.

[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 relationship between the pre-annealing time and the magnetic characteristics. FIG. 2 shows the annealing thermal cycle used to obtain the results of FIG.

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, quasi warm rolling at a sheet temperature of 400 ° C. or less, annealing and insulating coating treatment. In the production, in the annealing treatment, pre-annealing is performed at a temperature of 200 to 400 ° C for 1 minute to 3 hours, and then 1 hour at a temperature of 800 to 1300 ° C.
A method for manufacturing a high-silicon iron plate, which comprises performing final annealing for 10 minutes to 10 minutes. 2. A pre-annealing at a temperature of 200 to 400 ° C. for 1 to 10 minutes, followed by immediate heating, and a final annealing at a temperature of 800 to 1300 ° C. for 1 to 10 minutes. A method for producing a high silicon iron plate according to claim (1).