JPS6251202A - Manufacture of grain oriented silicon steel plate with low iron loss - Google Patents

Abstract

PURPOSE:To obtain a grain oriented silicon steel plate with low iron loss, whose characteristics does not deteriorate even in a case in which annealing for remov ing distortion is done, by removing locally a forsterite film coated after the final finishing annealing, by depositing metal different from the matrix iron onto the removed section, and by melting and coagulating it. CONSTITUTION:A cold rolled plate being made a final plate gauge, is decarbonized and annealed, then is coated with an annealing separation agent containing MgO as a principal ingredient, is rolled into a coil shape, and is annealed finally. At this time, a forsterite film is coated on the surface of the steel plate. Next, the forsterite film is removed into continuous or noncontinuous lines, and onto the concave metal different from the matrix iron, for example Al, Cu, Cr, Sn, Sb, or Ni, may be deposited with plating or evaporation. Next, the metal is melted on the deposited section on the forsterite film. In this way, the grain oriented silicon steel plate having elastic distortion added when the metal is coagulated after the melting, hardly can deteriorate the iron loss characteristics, even if annealing for removing distortion would be done at about 800 deg.C for 1min - several hours.

Description

[Detailed Description of the Invention] (Industrial Application Field) Regarding the method for manufacturing grain-oriented silicon steel sheets with low core loss, the technical content described in this specification is particularly focused on the production of grain-oriented silicon steel sheets by processing the forsterite coating on the surface of the steel sheets. It is related to improving iron loss characteristics.

Grain-oriented silicon steel sheets are mainly used as iron cores for transformers and other electrical equipment, and are known for their excellent magnetization properties, especially their low iron loss (W, represented by 1.5°).
is required.

For this purpose, firstly, the secondary recrystallized grains in the steel sheet should be <001
>It is necessary to highly align the grain orientation in the rolling direction, and secondly, it is necessary to reduce as much as possible the impurities and precipitates present in the final product steel.

Grain-oriented silicon steel sheets manufactured with this consideration have been improved over the years through many improvement efforts, and recently products with a thickness of 0.30 mm have achieved W17/
S. A low iron loss with a value of 1.05 W/kg has been obtained.

However, after the energy crisis a few years ago, the tendency to seek electricity with less power loss became even stronger, and grain-oriented silicon steel sheets with even lower core loss were required as the core material for these. It's here.

By the way, methods to reduce the iron loss of grain-oriented silicon steel sheets include increasing the Si content, reducing the thickness of the product sheet, making the secondary recrystallized grains thinner, reducing the impurity content, and (110) ( Metallurgical methods are generally known, such as aligning the secondary recrystallized grains of orientation to a higher degree, but these methods have already reached their limits with current production methods. It is extremely difficult to improve -L beyond this point, and even if some improvement is recognized, the effect of improving iron loss is small compared to the efforts made.

(Prior art) Apart from these methods, as disclosed in Japanese Patent Publication No. 54-23647, secondary recrystallization grains are made finer by forming a secondary recrystallization prevention region on the surface of a steel sheet. A method has been proposed to make this possible. However, this method
Since the control of the secondary recrystallized grain size is not stable, it cannot be said to be practical.

In addition, in Japanese Patent Publication No. 58-5968, micro-strain is introduced into the surface layer of the steel plate after secondary recrystallization using ballpoint pen-shaped small balls, thereby making the width of the magnetic domain finer and reducing the negative iron content. Japanese Patent Publication No. 57-2252 discloses a technique for irradiating the surface of a final product plate with a laser beam at intervals of several eleven times perpendicular to the rolling direction to introduce high dislocation density regions in the iron loss surface layer. Accordingly, a technique has been proposed to reduce the iron content by making the width of the magnetic domain finer. Furthermore, Japanese Patent Application Laid-Open No. 57-188810 proposes a similar technique in which microstrain is introduced into the surface layer of a steel sheet by electrical discharge machining to refine the magnetic domain width and reduce iron loss.

All of these three methods aim to reduce iron loss by refining the magnetic domain width by introducing minute plastic strain to the surface layer of the steel sheet after secondary recrystallization, and are equally practical. It is also effective in reducing iron loss, but strain relief annealing and baking of coatings after punching, shearing, and winding of steel sheets are performed by heat treatment such as processing.
This has the disadvantage that the effect of introducing plastic strain is diminished. In addition, if a minute plastic strain is introduced after the coating process, the insulating coating must be reapplied to maintain the insulation properties, resulting in a significant increase in the strain application process and reapplication process, which increases the cost. Bring on the amp.

(Problems to be Solved by the Invention) The present invention uses a means for refining the magnetic domain width, which is different in concept from the prior art described above, so that even after strain relief annealing at high temperature, the characteristics do not deteriorate. The object of the present invention is to provide a method for manufacturing a grain-oriented silicon steel sheet that can ensure the effectiveness of magnetic domain width refinement of the product.

(Means for Solving the Problems) This invention subjects a silicon-containing hot-rolled sheet to one cold rolling or two or more cold rollings with intermediate annealing in between to obtain the final sheet thickness, and then removes the hot rolled sheet. When producing grain-oriented silicon steel sheets by applying charcoal annealing, applying an annealing separator, and then performing final annealing, the forsterite film formed after final annealing is locally removed. A grain-oriented silicon steel sheet with low iron loss, characterized in that a metal different from the base iron is adhered to the forsterite-removed portion of the steel plate, and then thermal energy is applied to the metal adhesion area to melt and solidify the adhered metal. This is a manufacturing method.

The material to which this invention is applied is a known steel making method such as a converter,
A hot-rolled coil obtained by manufacturing steel using an electric furnace or the like, forming a slab (steel billet) by an ingot-blowing method or a continuous casting method, and then hot rolling is used. This hot rolled sheet desirably has a composition containing about 2.0 to 4.0x of St.

This is because if the Si content is less than 2%, the improvement in iron loss is not sufficient, and if it exceeds 4.0x, the cold workability deteriorates.

As for the other components, any material components of grain-oriented silicon steel sheets can be used.

Next, the final target plate thickness is achieved by cold rolling, and the cold rolling is performed once or twice with intermediate annealing interposed therebetween.

The cold-rolled sheet with the final thickness is then subjected to decarburization annealing and M
An annealing separator containing gO as a main component is applied, the material is wound into a coil, and final annealing is performed. At this time, a forsterite film is formed on the surface of the steel plate.

Then, after removing the unreacted annealing separator, locally
The forsterite coating is removed, preferably in a continuous or discontinuous line, and a metal different from the base iron is deposited. A suitable metal is A7! , Cu+C,
r+ Sn1. Sb, Ni, and the like are suitable, and are deposited in the recesses formed on the forsterite coating by plating or vapor deposition. In addition, regarding the partition form in the case of linear adhering regions, the width is 0.1 to 2.0 mm, the direction is at an angle of about 60 to 90 degrees with respect to the rolling direction, and the mutual line spacing is 2 to 2.0 degrees. Approximately 15 fins are desirable.

Note that in the case of discontinuous lines, the effect is diminished when the separation distance becomes Q, 5 mm or more.

Then, thermal energy is applied to the metal adhesion area on the forsterite coating to melt the metal.
As a means for applying such energy, any method that can apply energy to a very small portion, such as a laser beam or electrical discharge machining, can be used.

(Function) Through this treatment, a minute elastic strain is introduced into the surface of the steel plate and within the base metal in the vicinity thereof when the metal melts and then solidifies.

Note that at this time, plastic strain that is unavoidably caused by the heat generated at the same time is removed during the subsequent heat flattening.

In grain-oriented silicon steel sheets, which are subjected to elastic strain introduced when the metal is melted and then solidified, high dislocation density regions such as plastic strain regions and laser irradiation marks are formed on the surface layer of the steel sheet. Unlike the conventional method where
Since no artificial plastic strain f4M is observed, the
It has the notable advantage that there is almost no deterioration in iron loss even when strain relief annealing is performed at around 0°C for a period of 1 minute to several hours. In the former case, the plastic strain in the surface layer of the isthmus is eliminated by high temperature, resulting in deterioration of iron loss, which is a fatal drawback. It does not lose its effectiveness regardless of the situation.

(Example) Example 1 A silicon steel material containing Si; 3.23χ was made into a cold-rolled steel plate with a thickness of 0.30 mm according to a conventional method, and then decarburized.
Next recrystallization annealing was performed, then an annealing separator containing MgO as a main component was applied, and final finish annealing was performed.

After removing the obtained forsterite film on the surface in a linear manner with a scribing needle, the removed portion was partially plated with copper by applying a 5% copper sulfate solution.

At this time, the shape of the partial plating area has a width of 0 perpendicular to the rolling direction.
．． It has a linear shape of 5 cranes, and the distance between the lines is 5 cranes.

Next, one part of the partially copper-plated material was irradiated with a laser from above the plating layer to melt and solidify the copper on the base metal, and then a phosphate-based coating was applied. .

The other part was partially plated with copper and then immediately coated with a phosphate coating without melting or solidifying the plated metal.

Furthermore, another part was not plated but was coated with a phosphate coating to serve as a comparison material.

The results of investigating the magnetic properties of each product obtained are shown below.

Example 2 A grain-oriented silicon steel material containing S i; 3.25χ was made into a cold-rolled steel plate with a thickness of 0.23 m according to a conventional method, subjected to decarburization primary recrystallization annealing, and then made into a sheet containing MgO as the main component. An annealing separator was applied and final annealing was performed.

After removing the obtained forsterite coating in a continuous linear manner with a scribing needle, a nickel sulfate aqueous solution (loog
Previous partial plating was applied by applying Mu0.

The shape of the partial plating is 0.3 mm wide perpendicular to the rolling direction.
The distance between the line and the cotton was 6 l.

One part of the partially plated material was coated with a phosphate-based coating.

On the other part, a laser was irradiated onto the plating layer to melt the Ni, which was then solidified and then coated with a phosphate coating.

Furthermore, the other part was not subjected to partial plating but was coated with a phosphate-based coating to serve as a comparative material. The magnetic properties of the obtained product were investigated. The results are shown below.

Example 3 A silicon steel material containing SiH3,20χ was made into a cold-rolled steel plate with a thickness of 0.23 mm according to a conventional method, and then subjected to primary recrystallization annealing for decarburization, and then treated with an annealing separator mainly composed of MgO. After coating, final finish annealing was performed.

``After removing the obtained forsterite coating in a linear manner with a scribing needle, electroplating was performed in an antimony sulfate solution to apply antimony partial plating.At this time, the shape of the partial plating area was perpendicular to the rolling direction. It was cotton-like with a width of 0.51 cm, and the interval between lines was 31.

One part of the partially plated material was irradiated with a laser from above the plating layer to melt and solidify the antimony, and then a phosphate-based coating was applied.

The other part was coated with a phosphate coating while remaining partially plated.

Furthermore, the other part was coated with a phosphate coating without any partial plating, and was used as a comparison material.

(Effects of the Invention) According to the present invention, it is possible to obtain a grain-oriented silicon steel sheet with low core loss and whose properties do not deteriorate even when subjected to strain relief annealing.

Claims (1)

[Claims] 1. A silicon-containing hot-rolled sheet is subjected to one cold rolling or two or more cold rollings with intermediate annealing to obtain the final sheet thickness,
Then, when manufacturing grain-oriented silicon steel sheets by decarburizing annealing, applying an annealing separator, and then final annealing, the forsterite coating formed after the final annealing is locally removed. A directional steel with low iron loss characterized by removing forsterite, attaching a metal different from the base iron to the removed part of the forsterite, and then applying thermal energy to the metal attachment area to melt and solidify the attached metal. Manufacturing method of raw steel plate.