JPH04301034A - Production of grain-oriented pure iron sheet excellent in magnetic permeability in coil-width direction - Google Patents

Abstract

PURPOSE:To produce a grain-oriented pure iron sheet excellent in magnetic permeability in a coil-width direction. CONSTITUTION:In a manufacturing process for 8 grain-oriented pure iron sheet where a slab having a composition consisting of, by weight, 0.003-0.03% Al, 0.001-0.01% N, 0.01-0.1% C, and the balance iron is subjected, in succession, to heating, hot rolling, cold rolling, decarburizing annealing, and then final annealing at a temp. causing no transformation, cold rolling is performed so that the hot rolled plate is first cold-rolled in the direction equal to the hot rolling direction and then cold-rolled, without delay, in the direction perpendicular to the hot rolling direction at respective cold rolling rates satisfying the following inequality: 30% <= (cold rolling rate in the direction equal to hot rolling direction) <= (cold rolling rate in the direction perpendicular to hot rolling direction) <=75%.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to pure iron having excellent magnetic permeability and a method for producing the same.

[0002] Generally, yoke materials or magnetic shielding materials for magnetic circuits are required to have excellent direct current magnetization characteristics. High magnetic flux density, high magnetic permeability, and low coercive force lead to, for example, stronger electromagnets, higher sensitivity, and reduced residual magnetism, and as magnetic shielding materials, they reduce leakage magnetic fields and reduce the weight of shielding materials. Since iron has a high saturation magnetic flux density, it is suitable for the above uses, and attempts have been made for more than 60 years to improve the magnetic permeability and coercive force of pure iron. Among these, the present invention provides a method for manufacturing thin pure iron having a high saturation magnetic flux density and extremely excellent magnetic permeability in the coil width direction.

0003

BACKGROUND OF THE INVENTION Three main methods have been used to improve the direct current magnetization characteristics of pure iron: high purity, coarsening of crystal grains, and orientation control.

[0004] Repeated high-temperature hydrogen treatment in the laboratory,
Pure iron with as few impurities as possible has an initial permeability of 1,000, a maximum permeability of 200,000, and a coercive force of 0.05 (Oe) (RM. Bozorth: Ferromagneti).
sm (1951)) was obtained. Since there is a limit to industrial purification, in addition to purification, crystal grains are coarsened at the same time to improve DC magnetization characteristics.

Recently, aluminum has been added to pure iron by about 1%, and steel has been made into a single phase α up to high temperatures. By heat treating the steel for a long time at high temperatures, the grain size has been coarsened to 2 to 6 mm, and the maximum magnetic permeability has been increased to 4.
9000, coercive force 0.19 (Oe) (NKK Technical Report No.
．． 130 (1990) p. 32) Obtained. Since these coarse grains do not have a specific crystal orientation, they are suitable for applications where a magnetic field is applied in multiple directions, but there is a lot of room for improvement in properties in only one direction. Since iron that is easily magnetized in a specific direction is required for applications such as yoke materials that are magnetized in a specific direction, the third method, orientation control, has also been used for a long time. For example, D. M. K
ohler (J. Appl. Phys. 38 (1967
)1176) states that pure iron secondary recrystallized using MnS has extremely superior direct current magnetization characteristics compared to iron without conventional orientation control. All of these techniques align the <001> axes in the longitudinal direction of the coil, and differ from the present invention in this point.

[0006] In fields such as magnetic shielding, where demand has increased in recent years, pure iron is sometimes used as a building material for shielding, and when the material is used for a wider area than the current coil width, it may be bonded by welding, etc. There is a need. As is well known, adhesion deteriorates magnetization properties, so it is important to industrially obtain materials with excellent magnetization properties in the width direction.

As a means of obtaining excellent magnetic permeability in the width direction of the coil, the present inventors separately proposed a technique in which cold rolling is performed only in a direction perpendicular to the hot rolling direction. Considering the thickness that can be hot-rolled with the current hot-rolling capacity, it seems that the final thickness is about 0.35 mm. Now that rolled metal foils have begun to appear on the market and are being explored for a variety of uses, there is a need for a technology that can differentiate materials from thin to thick materials with equally excellent magnetization properties.

[0008]

SUMMARY OF THE INVENTION The present invention provides a method for producing pure iron having excellent magnetic permeability in the width direction of the coil and having a thin plate thickness.

[0009]

[Means for Solving the Problem] The gist of the present invention is that Al: 0.003 to 0.03%, N
: 0.001-0.01%, C: 0.01-0.1%
In the manufacturing process of unidirectional pure iron, in which a slab consisting of the remainder iron is heated, hot-rolled, cold-rolled, decarburized annealed, and then final annealed in a temperature range that does not undergo transformation, the cold rolling is performed at a cold rolling rate of the following formula: The present invention provides a method for producing thin pure iron having excellent magnetic permeability in the width direction of the coil, which is characterized by first cold rolling in the same direction as the hot rolling direction and immediately cold rolling in a direction perpendicular to the hot rolling direction. 30%≦Cold rolling rate in the same direction as the hot rolling direction≦Cold rolling rate in the direction perpendicular to the hot rolling direction≦75%

The slab used here may be obtained by known means, for example by continuous casting. Further, the slab heating time may be set to a time that allows sufficient homogenization depending on the slab thickness. Decarburization annealing is also performed by known means. For example, heat treatment may be performed in wet hydrogen. The final annealing is preferably performed at a high temperature in a temperature range where α-γ transformation does not occur, and the annealing time is set to a time that allows sufficient growth of secondary recrystallized grains.

[0011]

[Operation] First, the components of the starting materials will be described. C is useful for making the hot-rolled structure fine and uniform, and develops the {111} orientation after cold rolling and decarburization annealing with a cold rolling rate of 75% or less,
In order to enhance the selectivity of the {110}<011> orientation preferential growth, 0.01 to 0.1% by weight is added. The lower limit is the amount of C that does not make the hot-rolled structure coarse, and the upper limit is 0.1% by weight in order to shorten the decarburization time as much as possible. Al is A
In the form of lN, it acts as an inhibitor that suppresses the growth of grains with orientations other than the {110}<011> orientation.
At least 0.003% by weight Al is required. Adding more than the necessary amount of Al is not only harmful to the magnetization properties, but also suppresses the growth of {110}<011> grains, so the upper limit was set at 0.03% by weight. N is required to form AlN, which is necessary to cause secondary recrystallization.
Although 0.001% by weight is required, the upper limit was set at 0.01% by weight based on the same concept as in the case of Al. For other elements, {110}<011 of the present invention
>Addition is permitted within a range that does not hinder the generation of oriented secondary recrystallized grains. For example, Si, Ti, etc. may be added for the purpose of increasing the initial magnetic permeability, or Mn, etc. may be added for the purpose of improving hot embrittlement. This also includes impurity elements that are unavoidably included during the steel manufacturing stage.

[0012] In order to increase the magnetic permeability in the coil width direction,
The cold rolling rate in the direction perpendicular to the hot rolling direction must be equal to or higher than the cold rolling rate in the same direction as the hot rolling direction. This cancels the rolling texture formed in the same direction as the hot rolling direction and forms a new rolling texture in the direction perpendicular to the hot rolling.
This is because it is essential for the generation of <011> oriented grains. If the cold rolling rate is too low, not only will it not be suitable for thinning which is the purpose of the present invention, but also secondary recrystallized grains will not be generated or
Even if it occurs, sufficient magnetism cannot be obtained. If the cold rolling rate is too high, the magnetic permeability in the coil width direction also decreases. The cold rolling rate was limited to 30 to 75% for the purpose of the present invention to obtain high magnetic permeability.

[0013]

[Example] (Example 1) C: 0.04% by weight, Al:
A hot-rolled sheet containing 0.020% by weight, N: 0.006% by weight and the remainder made of iron was used as a starting material, and after cold-rolling in the same direction and perpendicular direction to the hot-rolling direction under the cold-rolling conditions shown in Fig. 1, 830 ℃
Decarburization annealing (in wet hydrogen) and final annealing at 890°C for 20 hours were performed to obtain a material having the magnetic permeability shown in Figure 1. With the cold rolling rate range of the present invention, thin pure iron having high magnetic permeability in the width direction of the coil after secondary recrystallization could be obtained.

(Example 2) No. 2 in Table 1. A hot-rolled sheet having a composition of 1 to 4 is used as a starting material, and 60% is applied in the same direction as the hot-rolling direction.
Subsequently, 60% cold rolling was performed in the direction perpendicular to the hot rolling direction, and decarburization and final annealing were performed under the same conditions as in Example 1. As a result, pure iron having the magnetic permeability shown in Table 1 was obtained. According to the components of the present invention, thin pure iron having excellent magnetic permeability in the width direction of the coil could be manufactured.

[0015]

[Table 1]

[0016]

[Effects of the Invention] According to the present invention, it is possible to manufacture pure iron with excellent magnetic permeability in the width direction of the coil and with a thin plate thickness.
The industrial benefits are huge.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between the magnetic permeability in the coil width direction and the cold rolling rate (in the case of a direction perpendicular to the hot rolling direction and in the same direction) when a magnetic field of 10 (Oe) is applied.

[Figure 2] {110} with easy magnetization axis in the coil width direction
FIG. 2 is a schematic diagram of secondary recrystallized grains with <011> orientation.

Claims (1)

[Claims] Claim 1: Al: 0.003 to 0.00% by weight.
03%, N: 0.001-0.01%, C: 0.01
In the manufacturing process of unidirectional pure iron, a slab consisting of ~0.1%, balance iron is heated, hot-rolled, cold-rolled, decarburized annealed, and then final annealed in a temperature range that does not undergo transformation. Thin unidirectional pure iron with excellent magnetic permeability in the width direction of the coil is characterized by being first cold rolled in the same direction as the hot rolling direction and then immediately cold rolled in the direction perpendicular to the hot rolling direction at a cold rolling rate of . Production method. 30%≦
Cold rolling rate in the same direction as the hot rolling direction ≦Cold rolling rate in the direction perpendicular to the hot rolling direction ≦75%