JPS6336906A - Rolling method for high-silicon iron sheet - Google Patents

Abstract

PURPOSE:To produce a high-silicon iron sheet contg. 4.0-7.0wt% Si so as to have good sheet thickness accuracy and high surface characteristic under high productivity by rolling the high-silicon iron sheet within a rolling temp. range controlled by the specific condition equation at the time of rolling said sheet. CONSTITUTION:The production of the high-silicon iron sheet contg. 4.0-7.0wt% Si with high production is permitted at the time of producing the high-silicon iron sheet from an ingot by stages including blooming-hot rolling-descaling-warm rolling-degreasing-surface treating-heat treating product fabricating, etc. More specifically, the rolling is executed at the rolling temp. Tr at which the rolling temp. during the the warm rolling in the above-mentioned stages satisfies the equation 20X[Si]-50<=Tr<=400. [Si] is Si content (wt%). The range is the temp. range within the hatched region according to the Si content. The production of the iron sheet which is good in both the surface characteristic and sheet thickness accuracy is thereby permitted.

Description

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

[Conventional technology and its problems]

Conventionally, silicon iron plates with a Si content of less than 4 wt% are classified into oriented silicon iron plates and non-oriented silicon iron plates depending on the manufacturing method, and are mainly used for laminated iron cores, wound iron cores for various electromagnetic induction devices, or electric shields. It has been processed and molded into cases, etc., and is put into practical use.

However, in recent years, there has been a strong demand for smaller size and higher efficiency of electromagnetic and electronic components from the viewpoint of resource and energy conservation, and materials with excellent soft magnetic properties, especially iron loss properties, are required. It is known that the soft magnetic properties of a silicon iron plate improve with the amount of Si added, and in particular, it exhibits the highest magnetic permeability at around 6.5 wt%, and also has a high specific electrical resistance, which reduces iron loss.

However, the workability of silicon iron plates deteriorates rapidly when the St-containing tray exceeds 4.0wt4, and for this reason, it was conventionally thought that it was impossible to manufacture high-silicon iron plates on an industrial scale by the rolling method. .

In recent years, a method called the ultra-rapid solidification method has been researched and developed in response to such rolling methods, but with this method, the high silica foil produced by iA has inferior surface properties and surface flatness. In addition, the thickness and width of the plate are limited, and in addition, productivity is poor and production costs are high, which poses many problems when implemented on an industrial scale.

In view of the current situation, it is an object of the present invention to provide a rolling method that makes it possible to manufacture high-silicon iron plates by rolling.

[Means to solve the problem]

As a result of studying the manufacturing technology of high-silicon steel sheets by rolling, the present inventors have found that by rolling at a predetermined rolling temperature, sufficient rolling workability can be achieved while ensuring good sheet thickness accuracy and surface texture. I found out what I can get.

That is, in the present invention, St is 4.0 to 7. When manufacturing a high-silicon iron plate containing Owt% by rolling, 20
[Si3-50≦Tr≦400, however, (811: Si
Its basic feature is that it is rolled at a rolling temperature Tr (° C.) that satisfies the content (wt %).

The present invention will be explained in detail below.

In the production of high-silicon iron plates by the rolling method, the present inventors
First, its rolling workability was investigated.

Specifically, the rolling workability of a high-silicon iron plate containing 6.5 wt% st was evaluated by a taper rolling test method based on the test piece number shown in FIG. FIG. 2 shows the results, and from this it is possible to clearly understand the characteristics of the rolling workability of the material as follows.

1) Materials with a cast structure (hereinafter referred to as ingot materials; equiaxed grain size of 10 to 30 squares) have extremely good workability at high temperatures exceeding 900°C;
It deteriorates linearly at temperatures below 600°C and becomes almost impossible to roll.

2) Material whose structure has been refined by hot rolling → recrystallization, or material whose grain boundary spacing in the thickness direction has been narrowed by hot rolling to form a processed wire (hereinafter referred to as rolled material) In this case, the processing limit is much wider than that of ingot material, depending on the grain size or grain boundary spacing in the thickness direction of the material. In other words, for a rolled material with a grain size of 1 m, the temperature is approximately 250°C and the grain size interval is 5.
Rolled materials with a 0μ shoulder lose their rolling workability at about 80°C, but normal rolling is possible at temperatures above that temperature range.

3) Therefore, what is the rolling workability of high-silicon steel plates?

It is highly dependent on the material structure and rolling temperature during rolling and cannot be rolled. In other words, there is a distinct temperature limit at which plasticity completely disappears, and normal cold rolling is impossible (in normal blooming → hot rolling, the rolling limit is a grain boundary spacing of about 50μ corners in the material thickness direction). ) can be said to be a major feature.

Based on this knowledge, Si
The rolling workability of a high-silicon iron plate having a content of 4.0 to 7.0 wt% was evaluated. Figure 3 shows the results.
As a result, it was found that the rolling processing limit temperature Tl(C) of a high-silicon iron plate can be expressed by equation (1).

Tl≧20x(Si3-so・・・・・・・・・・・・
・・・・・・・・・・・・(1) However, [Si3: Si content (wt ratio)] According to this, the rolling processing limit temperature is S
As the i content increases, the temperature shifts to the higher temperature side, and normal cold rolling is impossible in any case.

If normal cold rolling is possible, deterioration of surface properties and poor plate thickness accuracy will not be a problem.However, as mentioned above,
In order to ensure rolling workability, rolling must be performed at a high temperature above a certain level, and therefore, in this case, the oxidizability of the material during rolling must be taken into consideration. It has been conventionally said that oxidation is prevented when an iron plate contains ST, but it is necessary that this allowable saturation range 4 coincides with the above-mentioned temperature range in which rolling workability is ensured. From this point of view, 81 is 4.0-7. Oxidation properties were investigated using a high-silicon iron plate containing owt*. FIG. 4 shows the results, and it has become clear that about 400°C is the limit of the allowable degree of oxidation. That is, from this point of view, the rolling limit temperature Ta
CC%! It is expressed by the following formula (2).

T2=≦400・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・(2) To summarize the above study results, the rolling conditions for manufacturing high-silicon steel plates with good surface texture and thickness accuracy by rolling method are as shown in Figure 5. This is the rolling temperature range that satisfies the rolling temperature Tr of the following equation (3).
(°C) is required.

2 CD/, [Si3-50≦Tr≦400−・---
-------- An example of the manufacturing flow of a high-silicon iron plate using the curve (3) rolling method is as follows.

Ingot - Blooming Rolling - Hot Rolling - Descaling - Warm Rolling - Greasing - Surface Treatment - Heat Treatment - Product Processing During these steps, rolling according to the conditions of the present invention is performed in the above-mentioned "warm rolling".

In addition, in the above manufacturing process, descaling,
Wet rolling may involve unwinding and winding of the coil form. In such cases, if the strain caused by unwinding and winding is within the elastic deformation range of the material, it is possible to unwind and wind it in a cold state, but if plastic strain occurs, It is necessary to generate plasticity by heating the unwinding and winding portions of the material to a temperature within a range that does not cause breakage due to the generated plastic strain. If unwinding and winding are carried out in a temperature range that satisfies the above formula (3) according to the Si content, material breakage due to bending and unbending can be avoided within a predetermined bending radius.

〔Example〕

A high-silicon iron plate containing 6.5 wt% of Si was manufactured. First, the ingot was subjected to blooming and hot rolling under the following conditions.

Ingot weight: 5 tons Blowing conditions Soaking temperature: 1150℃ Slab dimensions: 150WI (thickness) x 650m (width) x 5
000mg (length) Hot rolling conditions Heating temperature: 1150°C Rough rolling thickness: 35■ Coil dimensions: 2m (thickness) x 650+m (width) After hot rolling, the coil was divided into two, and one side was subjected to the present invention conditions. The other cut plate was subjected to ordinary cold rolling as a comparative example. The rolling conditions are as follows. Note that FIG. 6 schematically shows the rolling equipment used for rolling under the conditions of the present invention, where (1) is the rolling mill, (2) is the rolling machine, and (2) is the rolling machine.
) is a heating device, (3) is a high temperature lubrication device, and (4) is an iron plate, and lubricant is supplied from the high temperature lubrication device (3) to the rolling part of the iron plate.

Inventive rolling conditions Heating temperature: 350°C Lubricating oil: Synthetic oil (approx. 200°C) Rolling reduction: 10 inches/pass Finished coil dimensions: 0.35 mg (thickness) x 300!
1m (width) cold rolling conditions (comparison material) Lubricating oil Synthetic oil (room temperature) Roll gap change amount 0.05 ma / Pass target finished dimension 0.351 (thickness) x 30 f) m (width)
In the above manufacturing examples, the method of the present invention was able to roll the coil to a predetermined size without edge cracking or other rolling cracks. On the other hand, in normal cold rolling as a comparative example,
Although the rolling reduction per pass is as light as skin bath rolling, various rolling cracks including edge cracks occur, and it is necessary to partially achieve the target finished thickness while trimming the cracks. Obtained.

Thereafter, the inventive material and the comparative material were subjected to surface treatment and heat treatment, and then rings with an outer diameter of 1511 mm and an inner diameter of 7 mm were punched out from them.

The magnetic properties of each were investigated. Note that the above heat treatment is 1
The test was carried out in a vacuum atmosphere at 200° C. for 1 hour.

Table 1 shows the rolling workability of the test materials in the above production examples,
The figure shows the surface texture mark) and the magnetic properties of the processed product, demonstrating that the method of the present invention enables industrial production of high-silicon iron plates.

〔Effect of the invention〕

According to the present invention described above, high-silicon steel plates with good surface texture and plate thickness accuracy can be manufactured with high productivity by the rolling method, and in recent years, there has been a strong demand for miniaturization and high-performance electromagnetic and electronic components. This makes it possible to industrially manufacture high-silicon iron plates that can respond to increased efficiency.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a taper rolled test piece subjected to the taper rolling test method. Figure 2 shows the rolling processability of L5wt%S1-containing steel plate measured by the taper rolling test method as a function of rolling temperature and 1.
1M, which is shown in relation to the critical reduction rate per pass.
Figure 3 shows the rolling limit of a high-silicon iron plate in terms of the relationship between the Si content and the rolling limit temperature. FIG. 4 shows the relationship between the heating temperature and oxidizability of a high-silicon iron plate. FIG. 5 shows the proper rolling temperature of a high-silicon iron plate in relation to the Si content. FIG. 6 is an explanatory diagram showing an outline of a rolling apparatus used in an embodiment of the present invention. Patent applicant: Nippon Kokan Co., Ltd. Inventor: Hikodo Ariizumi Masaaki Yoshino
Fuji 1) sentence between layers
Masu 1) Sada Sodo
Sickle 1) Masa Seido
Atsushi Inagaki −Representative Patent Attorney
Sho Yoshihara Sando Masato Tomabechi Attorney Hiroko Yoshihara Figure 5

Claims (1)

[Claims] A high-silicon iron plate containing 4.0 to 7.0 wt% of Si is produced by rolling at a rolling temperature Tr (°C) that satisfies the condition of the following formula. Method of rolling silicon iron plates. 20×[Si]-50≦Tr≦400 However, [Si]: Si content (wt%)