KR900006691B1 - Making process for si plate - Google Patents

Abstract

One directional silicon steel sheet is characterised by charging supersonic waves energy to steel sheet in final cold rolling or coiling process. Si steel sheet comprises up to 4.5 wt.% Si and has the final cold rolling rate of 81-95%. The Si steel sheet has high magnetic flux density.

Description

Manufacturing method of high magnetic flux density unidirectional silicon steel sheet with excellent magnetic properties

1 is a graph showing the effect of the ultrasonic energy applied during cold rolling on the hardness of the steel sheet after rolling ((a): relationship between frequency and hardness, (b): relationship between rolling rate and hardness, (c): temperature Relationship between hardness and

2 is a graph showing the relationship between the roughness and the hardness of the cold rolled sheet.

The present invention relates to a method for manufacturing a unidirectional silicon steel sheet used as a material such as an iron core of an electromagnetic device, and more particularly, to a method for manufacturing a high magnetic flux density unidirectional silicon steel sheet having excellent magnetic properties characteristic of a cold rolling process. It is about.

1

집합조직을 만들어 특성이 양호한 일방향성 규소강판을 만드는 데에 중요하다는 것이 잘 알려져 있다.A number of techniques have been proposed and patented so far for high magnetic flux density unidirectional silicon steel sheets, and the range covers components, steelmaking conditions, hot rolling processes, cold rolling processes, and surface treatment of steel sheets. As an example of the manufacturing method of the high magnetic flux density unidirectional silicon steel sheet which is characterized by the cold rolling process, Japanese Patent Laid-Open Publication No. 49-3331 is mentioned. , MnS as a grain growth inhibitor, characterized in that cold rolling of 81-95%, in general, high cold rolling is characterized by excellent magnetic properties (110)

One

It is well known that it is important for making a unidirectional silicon steel sheet having good characteristics by forming an aggregate structure.

However, in cold rolling, it affects the quality of products manufactured under various conditions in addition to those mentioned above.

For example, Japanese Patent Laid-Open No. 46-46511 (cold rolling method of overspeed density unidirectional electromagnetic steel strip (plate)) has a temperature of 50 ° C-350 ° C in cold rolling for example 250 It is proposed that the magnetic properties are improved when the temperature is higher than or equal to ℃.

In addition, Japanese Patent Application Laid-Open No. 49-34417 (manufacturing method of high magnetic flux density unidirectional silicon steel sheet) has a better characteristic that the smaller the diameter of the roll during the final cold rolling with respect to the effect of the diameter of the roll during cold rolling. A technique for rolling a final pass with a reduction of 10% or more using a roll of 300 mm or less in diameter is presented.

In addition, Japanese Patent Laid-Open Publication No. 51-41611 (cold rolling method of high magnetic flux density unidirectional electrical steel sheet which gives excellent characteristics) maintains the coil during cold rolling for a short time in a temperature range of 300 ° C to 600 ° C. Techniques for representing the same effects of the above technical effects have been presented.

According to the conventional technology as described above, in order to obtain a high magnetic flux density unidirectional silicon steel sheet having excellent characteristics, cold rolling is carried out at a high temperature using a roll having a small diameter, or 50 ^° C-600 during the cold rolling step. ^o It shows that it is necessary to heat-treat at a temperature between C. In the case of using a roll with a small diameter, the diameter of the roll is limited. Therefore, in a cold rolling machine having a large roll diameter, a high magnetic flux density unidirectional silicon steel sheet In the case of the method of heat-treating the coil during cold rolling, the heat treatment is required for a certain time in the temperature range of 300 ^° C.-600 ^° C. during cold rolling. Therefore, there has been a demand for new technologies that are excellent in product quality and economics at the same time.

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측이 압연방향에 평행한 {100}

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,{112},

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{111}

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등으로서 냉간압연에 의해 쉽게 에너지를 축적시키지도 않고 결정방위도 변화하지 않기 때문에 이후 소둔시 재결정이 제대로 발생하지 않는 결정립들이다.Therefore. The present inventors have conducted detailed investigations on the causes of the constraints of the prior art, and as a result, have found that it is necessary to cold-roll at high rolling reduction to sufficiently destroy the hot-rolled structure. In the hot rolled tissue, there are largely stretched grains.

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{100} whose side is parallel to the rolling direction

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, {112},

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{111}

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For example, the crystal grains do not easily accumulate energy by cold rolling and do not change the crystal orientation.

In particular, when the compressive force perpendicular to the cross section is the main rolling stress, as in cold rolling using a large roll, recrystallization is more prone to occur due to elongated grains.

In order to solve this problem, a technique for performing cold rolling using a small roll has been proposed. The reason for using a small roll is that the tensile force acts as a rolling stress in addition to the compressive force, resulting in more complex deformation, which leads to increased energy accumulation and determination. This is because a change in orientation also occurs, which increases the tendency of recrystallization in subsequent annealing.

Further, in the conventional publicly known art, the reason why the cold rolling temperature is increased or the low temperature annealing is performed in the middle is that the work hardening by cold rolling increases significantly compared with the case where it is not. Appears only in the solid solution, dislocations move because a group of warm-ups are generated by the action of the main action slip system during plastic deformation by cold rolling, and the carbon or nitrogen dissolved therein forms a diffusion atmosphere. As it becomes difficult to do this, if the main active slip system becomes difficult to move, the other slip system moves instead. As a result, the deformation becomes complicated and the work hardening increases.

Therefore, it can be seen that high cold rolling temperature or low temperature annealing during cold rolling is necessary for the diffusion of the carbon or nitrogen dissolved.

The present inventors have proposed the present invention on the basis of the above results, the present invention is to provide a method for producing a high magnetic flux density unidirectional silicon steel sheet having economic properties and magnetic properties equivalent to those of conventional ones. There is this.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

The present invention provides a high magnetic flux density unidirectional silicon in which a silicon steel sheet containing not more than 4.5 wt% of silicon is subjected to carbon annealing and final annealing after the final product is plated by cold rolling at least once or two times including intermediate annealing. In the production of steel sheet, the present invention relates to a method for producing a high magnetic flux density unidirectional silicon steel sheet having excellent magnetic properties by applying ultrasonic energy to the steel sheet during rolling or winding during final cold rolling.

In addition, the present invention, except for the final pass during the final rolling, cold rolling using a work roll (work roll) so that the surface roughness of the steel sheet has a range of 30-150μ inch high magnetic flux excellent in magnetic properties It relates to a method for producing a unidirectional silicon steel sheet.

In the present invention, the reason for imparting ultrasonic energy during cold rolling or winding is that the ultrasonic energy activates the diffusion of the dissolved carbon or nitrogen in the steel, thereby fixing the potential in a short time at room temperature to promote work hardening In order to solve the problems of the conventional methods requiring heating or low temperature annealing during cold rolling, the results of experiments performed by the present inventors on the application of ultrasonic energy are shown in FIG.

Fig. 1 (a) shows the results of measuring the change in hardness using a supersonic wave of frequency 1-100KHz and shows the result. As shown in Fig. 1 (a), work hardening is accelerated by applying ultrasonic energy. In particular, it can be seen that the effect is greatly obtained around 20KHz. 1 (b) and (c) show the change in hardness according to the rolling rate and the change in hardness according to the temperature, respectively, for the case of applying the ultrasonic wave of 20 KHz and the case of not giving the ultrasonic wave of 20 KHz. It can be seen that in the case of not imparting, greater work hardening effect can be obtained at lower rolling rates and lower temperatures.

On the other hand, in the case of using a roll having a rough surface roughness, the rolling stress dispersed in the vertical stress, which is the main rolling stress by the rough surface, acts to promote work hardening as a number of slip systems move, and the surface roughness of the steel sheet is promoted. The second recrystallization rate is lower when using a work roll that is 30 μ inch or less, and cold rolling is difficult when 150 μ inch or more. Therefore, the work roll is preferably selected to obtain a surface roughness of 30 μ inch to 150 μ inch. Do.

2 is a graph showing the effect of the surface roughness of the steel sheet on the hardness after cold rolling during cold rolling using a rough surface roughness roll, it can be seen that the increase in hardness is more than 30μ inches or more surface roughness.

Hereinafter, a method of manufacturing a high magnetic flux density unidirectional silicon steel sheet in accordance with the present invention will be described according to the actual manufacturing process.

First, the component of the silicon steel according to the present invention is preferably a conventional silicon steel containing 4.5% or less of Si, among which 2.5-4.5% of Si, 0.085% or less of C, and 0.010-0.065% of Sol.Al. Silicon steel to be mentioned is more preferable, and NIn, N, Si, Se, etc. are added to a normal range here.

The components are adjusted in the steelmaking process so as to have the additive range as described above and cast into slabs by a continuous structure.

The slab is heated at a high temperature of 1200 ^° C. or more, preferably 1350 ^° C. or more, which is a normal heating temperature, and hot rolled to a hot rolled thickness of 1.8 mm to 2.5 mm.

The thickness of the hot rolled plate may vary depending on the cold rolling conditions or the thickness of the final product to be carried out in mind.

The hot rolled sheet is cold rolled to the final thickness by one or two cold rolling including intermediate annealing, and the carbon content is reduced to 0.003% or less by ordinary decarbonization annealing.

The final cold rolling is a basic process for obtaining a high magnetic flux density unidirectional silicon steel sheet, and in order to obtain a high magnetic flux density unidirectional silicon steel sheet, a final cold rolling rate of usually 80% or more, preferably 85% or more is required.

Also in the present invention, the final cold rolling rate as described above is required, in addition to the ultrasonic energy is applied to the steel sheet during cold rolling or winding, more preferably, the surface roughness of the steel sheet except for the final pass during the final rolling Cold rolling is performed using a work roll that is 30-150μ inch.

The cold rolling may be performed using cold rolling mills of various types such as tandem, reverse, 2 high, 4 high, 6 high, and 10 high.

As described above, annealing separator is applied to the final cold rolled and decarbonized cold rolled steel sheet in a conventional manner, and secondary recrystallization is generated by final annealing which is cracked at 1200 ^° C. for about 20 hours.

Subsequently, continuous annealing which serves as a gradation of the steel sheet and the insulation coating is performed to produce a product.

The present invention can be preferably applied to manufacturing processes other than the manufacturing process according to the conventional method described above.

Hereinafter, the present invention will be described in detail through examples.

Example 1

Hot rolled sheet 2.5mm thick, containing Si: 3.15%, Mn: 0.07%, C: 0.05%, A1: 0.025%, S: 0.025%, N: 0.007% Other Fe and inevitably mixed impurities Was annealed at 350 ^° C. for 3 minutes, pickled and cold rolled to 0.3 mm.

Here, in order to explain the effect of the ultrasonic energy, one was given 20 KHz of ultrasonic energy to the steel sheet during cold rolling (Invention Example 1), and the other was prepared without applying ultrasonic waves. (Prior example) The hot rolled plate with the same thickness of 2.5mm was annealed for 3 minutes at 350 ° C, pickled, and cold rolled to 0.23mm.In this case, gymnastics was applied by applying 20KHz sound and energy during cold rolling. Honor 2)

After cold rolling as described above, decarbonized annealing in a gas atmosphere of 75% H ₂ + 25% N ₂ for 3 minutes at 850 ^° C., annealing separator added with TiO ₂ to MgO, and then applied at 1200 ℃ After the final annealing in a hydrogen atmosphere, the final product was prepared through a process of hot calibration, the magnetic properties and secondary recrystallization rate was measured for each, and the results are shown in Table 1 below.

Table 1

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방위를 힝성하는 2차재결정율이 97%인데 비하여 본발명예 1 및 2의 경우에는 l00%로, 이는 냉간압연에 의해 가공경화가 촉진되어 열간압연조직이 충분히 파괴되었음을 나타내는것이다.As shown in Table 1, Examples 1 and 2 of the present invention to which ultrasonic energy is applied during cold rolling or winding are not only improved in magnetic flux density but also significantly reduced in iron loss as compared with the conventional method in which ultrasonic energy is not applied. Method (110)

One

Compared with the secondary recrystallization rate of 97%, the orientation of the present invention Examples 1 and 2 was 100%, indicating that the hot rolling was sufficiently destroyed by the work hardening by cold rolling.

Example 2

The steel of the same component as in Example 1 was treated under the same conditions except for cold rolling.

10μ인치)를 가진 워크롤을 사용한 냉간압연도 실시하여 각각에 대하여 자기적 특성 및 2차 재결정을을 측정하고 그 결과를 하기 표 2에 나타내었다.Cold rolling was performed in 5 passes to a thickness of 0.3mm. At this time, the surface roughness of the work roll was adjusted so that the surface roughness of the steel sheet was 20μ inch, 30μ inch, 50μ inch, 70μ inch. Surface roughness

Cold rolling was also carried out using a work roll having a diameter of 10 mu inches to measure the magnetic properties and the secondary recrystallization for each, and the results are shown in Table 2 below.

[Table 2]

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방위의 2차 재결정율이100%로 되어 자기특성이 우수하게 됨을 알 수 있다.As shown in Table 2, when the surface roughness of the steel sheet is more than 30μ inches (110)

One

It can be seen that the secondary recrystallization rate of the orientation becomes 100%, resulting in excellent magnetic properties.

As described above, in the conventional method, it is necessary to limit the cold rolling roll to a small diameter and to provide a heating apparatus for cold rolling at high temperature or to perform low temperature annealing for at least 1 minute during cold rolling. It has the productivity and excellent effect to obtain a high magnetic flux density unidirectional silicon steel sheet having excellent magnetic properties without the constraints of cold rolling.

Claims (2)

Silicon steel sheets containing 4.5 wt% or less of Si are made into a thickness of the final product by one or two or more cold rollings including intermediate annealing at a final cold rolling rate of 81-95%, and then decarbonized and 1150 by a conventional method. ^{o In} the manufacturing method of high magnetic flux density unidirectional silicon steel sheet subjected to the final annealing at a temperature above C, the magnetic properties with excellent magnetic properties, characterized by applying ultrasonic energy to the steel sheet during rolling or winding during final cold rolling. Method for producing a fast density unidirectional silicon steel sheet. According to claim 1, wherein the cold rolling using a work (roll-rol1) to ensure that the surface roughness of the steel sheet 30-150μ inches except for the final pass during the final rolling, the porcelain excellent magnetic properties Method for producing a fast density unidirectional silicon steel sheet.

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