JPS61133321A - Production of ultra-low iron loss grain oriented electrical steel sheet - Google Patents

Abstract

PURPOSE:To execute magnetic domain segmentation having heat resistance and to produce an ultra-low iron loss grain oriented electrical steel sheet by removing the surface film of the grain oriented electrical steel sheet after finish annealing then straining the steel sheet before or after the formation of the film of an infiltrative material and subjecting the film to a heat treatment. CONSTITUTION:The surface film such as glass film, oxide film and insulating film on the grain oriented electrical steel sheet subjected to finish annealing is removed from the entire surface or at intervals by pickling, grinding, etc. The film of the infiltrative material such as metal, non-metal or salt is formed by coating, etc. on the steel sheet and the steel sheet is strained by an optical means such as laser irradiation or mechanical means such as small balls before and/after the formation of such film, then the film is subjected to the heat treatment at about 500-1,000 deg.C. The infiltrative material consisting of the steel component or different steel structure is thus formed at intervals on the above-mentioned steel sheet, by which the magnetic domain segmentation having the heat resistance is stably executed to a high degree without annihilation by stress relief annealing, etc. The grain oriented electrical steel sheet having the extremely low iron loss is thus obtd.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method for manufacturing grain-oriented electrical steel sheets with low core loss, and more specifically, the present invention relates to a method for producing grain-oriented electrical steel sheets with low core loss. The present invention relates to a method for manufacturing grain-oriented electrical steel sheets with extremely low iron loss.

(Prior Art) Grain-oriented electrical steel sheets are mainly used as iron core materials for transformers and other electrical equipment, so they need to have good excitation characteristics and iron loss characteristics.

This steel plate utilizes the secondary recrystallization phenomenon and has a rolling surface of (110
) plane has a <001> axis in the rolling direction, that is, secondary recrystallized grains having a so-called Goss orientation are developed.

By increasing the concentration of the (110) <001> orientation and reducing deviation from the rolling direction as much as possible, products with excellent excitation characteristics, iron loss characteristics, etc. are being manufactured. .

By the way, as the degree of integration of the (110) <001> orientation increases, the crystal grains become thicker (and the magnetic domain becomes larger because the domain wall penetrates the grain boundary), and the iron loss is lower compared to the increase in the degree of integration. There is a phenomenon that cannot happen.

For example, Japanese Patent Publication No. 58-5968 discloses a technique for eliminating the above-mentioned phenomenon and reducing iron loss.

This is done by pressing small balls etc. onto the surface of the final finish fired pure unidirectional electromagnetic steel sheet to form dents with a depth of 5μ or less and applying linear minute strain to subdivide the magnetic domains. It is intended to improve losses. In addition, special public service No. 58-2641
Publication No. 0 proposes that at least one trace of laser irradiation is formed on the surface of each crystal grain of secondary recrystallization generated by final finish annealing to subdivide the magnetic domain and reduce iron loss.

These Special Publications No. 58-5968 and Special Publication No. 58-264
According to the method shown in No. 10, iron loss is improved by applying local minute strain to the surface of a unidirectional electrical steel sheet,
Ultra-low core loss material can be obtained.

(Problems to be Solved by the Invention) However, when the ultra-low iron loss material obtained as described above is annealed, the effect of improving iron loss is lost. There is a problem that the improvement effect disappears.

The object of the present invention is to stably obtain grain-oriented electrical steel sheets with extremely low core loss by performing magnetic domain refining that does not eliminate the core loss improving effect even after heat treatment, such as stress relief annealing.

The present inventors performed strain relief annealing after magnetic domain refining, for example, at 700°C.
Many experiments were conducted to produce a grain-oriented electrical steel sheet with extremely low core loss through magnetic domain refining that does not lose its core loss improvement effect even when heat treated at temperatures of ~900°C.

(Means for Solving the Problem) As a result, an alloy layer is formed on the finish annealed grain-oriented electrical steel sheet due to a reaction with an intruder different from the steel composition or steel structure of the steel sheet, such as a steel sheet or a surface coating. When surface reaction products, diffused substances, etc. are formed by entering the steel plate at intervals,
Sprouts of magnetic domains occur on both sides of the intruder, and when the steel plate is magnetized, the magnetic domains are fragmented, and even if heat treatment such as stress relief annealing is subsequently performed, the iron loss improvement effect due to magnetic domain fragmentation does not disappear, and the iron loss improvement effect due to magnetic domain fragmentation does not disappear. It has been found that grain-oriented electrical steel sheets with extremely low loss can be obtained.

The present invention aims to provide a method for producing grain-oriented electrical steel sheets with extremely low core loss in a more highly stable manner. Surface coatings such as coatings, oxide coatings, and insulating coatings are removed, and then strain is applied to the steel plate before and/or after the re-intrusion body coating is formed on the steel plate, and the steel composition of the base steel is changed to the steel plate by heat treatment. Alternatively, there is a method for manufacturing an ultra-low core loss grain-oriented electrical steel sheet, which is characterized by forming intruders different from the steel structure at intervals to perform magnetic domain refining.

In the present invention, the term "intruder" refers to the state in which a coating on a steel plate is present in the steel plate as particles or lumps, either alone or in combination with components on the steel plate side, atmospheric components, etc. It is something.

"Reinvader" refers to a substance that can form an invader.

In addition, in the present invention, the term "coating" is a general term that includes all mechanical coating films, chemical adhesion films such as plating, or adhesives on at least a portion of the steel plate, and films that partially have a reaction layer. Yes, and its thickness is not specified.

Further, the above-mentioned heat-resistant magnetic domain subdivision can be performed as follows. In other words, surface coatings such as glass coatings, oxide coatings, and insulation coatings formed on finish-annealed grain-oriented electrical steel sheets are completely removed by pickling, corrosion, shot blasting, grinding, cutting, chemical polishing, solvents, etc. The steel plate is removed at intervals to expose the steel plate, and then the steel plate is treated with re-invaders such as metals, non-metals and mixtures thereof, alloys, oxides, phosphoric acid, boric acid, phosphates, and boric acid. A chemical agent such as a salt or a mixture thereof is formed into a film by coating, plating, vapor deposition, welding, etc., and strain is applied at intervals before and/or after the film is formed, by optical means such as laser irradiation, When it is applied by mechanical means such as small balls, grooved rolls, ballpoint pens, scribes, etc., and then heat treated, the re-penetrating body is in direct contact with the steel plate base metal, so that the re-penetrating body is in contact with the steel plate base metal. It reacts immediately in the absence of an intervening film, and the reaction is further promoted by the amount applied, so that it is possible to form the target interstitial bodies in the steel sheet and to achieve heat-resistant magnetic domain refining in a highly stable manner. In other words, the glass film or the like that is present when the re-invading body enters the steel plate is stabilized by a kind of heat treatment, so it cannot be said that the reaction activity is high, and it has an intrusion inhibiting effect. When the glass coating etc. are removed according to the present invention, the re-invading bodies react directly with the steel plate, and the reaction is further promoted by applying strain, and the reintruding bodies enter the steel plate in a manner that differs from the steel composition or steel structure. The interstitial bodies are formed at intervals with a higher degree of stability, resulting in heat-resistant magnetic domain refinement.

As a result, it becomes possible to select various attractive process advantages such as controllability of the degree of intruder formation (depth, etc.), relaxation of heat treatment conditions (temperature, time), etc. This more than compensates for the inconveniences associated with the additional process, and the W I? 150 <
Advantages in the process and/or product properties, such as the ability to easily achieve an ultra-low core loss of 0.80 W/kg, can be obtained by removing the glass coating, etc.

A specific example of the substance forming the reintrusion body will be described later, but any substance that reacts with the steel plate, its atmosphere, etc. through heat treatment and invades the steel plate may be used.

The present invention will be specifically explained below based on an example in which a finish annealed grain-oriented electrical steel sheet is coated with a chemical and heat treated.

In the present invention, the finish annealed grain-oriented electrical steel sheet is subjected to magnetic domain refining, but the steel composition of the grain-oriented electrical steel sheet and the manufacturing conditions until finish annealing do not need to be specified; for example, AIN is used as an inhibitor.

MnS, MnSe, BN, Cu, S, etc. are used as appropriate, and if necessary, Cu, Sn + Cr,
Contains elements such as Ni, Mo+ sb, etc., and further hot-rolls the slab and anneales it once or twice with annealing in between.
There is also no need to specify the conditions of a series of processes in which the sheet is cold-rolled several times or more to reach the final thickness, decarburized, annealed, coated with an annealing separator, and finished annealed.

By the way, the finish annealed grain-oriented electrical steel sheet has an oxide film containing SiO□ and MgO formed in the previous decarburization annealing process.
A glass coating (
forsterite film) is formed. This glass coating may inhibit the reaction between the chemical applied in the application example of the present invention and the steel plate substrate, and the underlying oxide film may also inhibit the above reaction. In order to alleviate these adverse effects, the agent promotes the reaction with the steel sheet base and the heat treatment atmosphere, and penetrates into the steel sheet to form a highly stable intruder that differs from the steel composition or steel structure. Removal of glass coatings, oxide coatings, etc. on steel plates, either entirely or at intervals, by pickling with sulfuric acid, hydrochloric acid, hydrofluoric acid, phosphoric acid, etc. or a mixture thereof, shot blasting, grinding, cutting, chemical polishing, solvent, etc. and expose the steel plate base. This exposure also includes the removal medium, such as acid, penetrating a portion of the base metal and forming a depression. When removing at intervals, local pickling, local grinding, cutting, solvent, shot blasting, etc. are used to remove at intervals of 1 to 3 (In).

Next, a chemical is applied to the grain-oriented electrical steel sheet over the entire surface or at intervals to form a film. In this example, the re-invading agents include AA, St, Ti, Sb, and Sr.

Cu, Sn+ Zn+ Fe+ Nt+ Cr+ M
Metals such as n, P, S+ B, nonmetals, mixtures thereof, oxides, alloys, phosphoric acid, boric acid, phosphates, borates, sulfates, nitrates, silicates, etc., and mixtures thereof. is used, and a film is formed by coating it in the form of a slurry or solution.

This coating is preferably formed at intervals when the glass coating or the like is removed over the entire surface, or preferably formed over the entire surface or at intervals when the removal is performed at intervals.

In the drug, metals, nonmetals, oxides and alloys thereof are preferably used in powder form.

When using powder of metals, nonmetals, their oxides, or alloys as a slurry, it is easier to apply by suspending it in water, so the concentration should be approximately 2 to 100 parts by weight per 100 parts by weight of water. do.

When metals, non-metals, or their oxides or alloys are used in combination with acids or salts, they may be applied as a undiluted solution or diluted with water to an appropriate concentration.

As mentioned above, the chemical is applied to the grain-oriented electrical steel sheet to form a film, but before or after the formation of the film, mechanical treatment such as a small ball, a grooved roll, a scriber, a ballpoint pen, etc. When strain is applied by optical methods such as laser irradiation or laser irradiation, the formation of interstitial bodies described later is promoted.

When applying strain before forming the film, the strain may be applied to the steel plate in the portion where the penetrant body is to be formed before removing the surface film such as the glass film. In addition, if the film is strained after it is formed, the film may be destroyed, so when applying the chemical, it may be necessary to make it slightly thicker or, for example,
Destruction of the coating can be solved by introducing a step of heat treatment at about 00° C. to strengthen the coating.

This strain is applied not to subdivide the magnetic domains by itself as in the past, but to encourage and stably increase the reaction between the coating and the steel sheet base during heat treatment and promote the formation of interstitial bodies. It is applied to steel sheets or their surface coatings.

Next, after drying the chemical, heat treatment at a temperature of 500 to 1,200°C will prevent the chemical from reacting with the steel substrate or the atmosphere when the temperature is raised or kept, because the glass coating has been removed. The reaction is facilitated by the addition of strain, and the chemical penetrates into the steel sheet steel, causing interstitial bodies such as alloy layers, surface reaction products, and diffused substances to form at intervals. It is formed after The formation of the intruders fragments the magnetic domain.

This heat treatment is performed in a neutral or reducing atmosphere containing H2. Microscopic structure photograph of an example of an invader (X100O)
is shown in Figure 1. In this figure, the object marked A is the intruder, and it can be seen that it has entered the steel plate sharply in the thickness direction.

The composition of the intruder is different from that of steel, and the structure is also different, for example, many buds of magnetic domains are created,
It is presumed that when a steel plate is magnetized, the buds of the magnetic domains extend and the magnetic domains become subdivided.

In the above explanation, an example was described in which the glass coating and oxide coating were removed, but the invention is not limited to this, and colloidal silica, colloidal silica, etc.
If an insulating film has been formed by applying aluminum phosphate, magnesium phosphate, chromic anhydride, chromate, etc. and baking it, remove the insulating film and then apply the same method as described above. Effects can be obtained.

Examples will be described below.

Example 1 C: 0.073, Si: 3.18, Mn: 0 in weight%
．． 06B, ^l: 0.032, S: 0.023, C
A silicon steel slab consisting of U: 0.07, Sn: 0.10, and the remainder iron was hot rolled, annealed, and cold rolled by a well-known method, and a steel plate with a thickness of 0.225 tm was then subjected to final annealing steps. carried out. Steel plate after final finish annealing “before treatment”
This was used as the sample material. The glass film and oxide film are removed from the steel plate using a pickling solution mixed with sulfuric acid, hydrochloric acid, hydrofluoric acid, and water.
GO! Irradiate the laser and roll it in the direction almost perpendicular to the rolling direction.
A slight strain is introduced in the f1 interval, and then the chemicals shown in Table 1 are applied to the entire surface so that the weight after drying is 0.5 g/rrf, and the film is laminated after being dried at an oven temperature of 400°C. Then, heat treatment was performed at 800° C. for 10 minutes to obtain a “treated” test material. After this, strain relief annealing was further performed at 800° C. for 2 hours to obtain a test material "after strain relief annealing."

As described above, the magnetic properties of each sample material were measured ``before treatment'', ``after treatment'', and ``after strain relief annealing''.

The measurement results are shown in Table 2.

Margin below: Table 1 Table 2 Example 2 Weight %: C: 0.085, Si: 3.27, Mn: 0
．． 073, Al: 0.028, S: 0.027, N:
0.0082, a silicon steel slab consisting of the balance iron is hot rolled, annealed, and cold rolled by a well-known method to give a 0.22
A 5 m thick steel plate was obtained.

Next, the well-known steps of decarburization annealing, application of an annealing separator mainly composed of MgO, and final finish annealing were carried out.

The steel plate after final annealing was used as the "before treatment" test material.

Next, the glass coating and oxide coating of the steel plate are removed by grinding.
The material was removed at intervals of 0,000 mm, and a coating was formed by applying the chemicals shown in Table 3 to a weight of 0.9 g/m after drying. 1
A slight strain was applied at intervals of 0+*+m. 800℃XIO
The specimen was heat-treated for 30 minutes to obtain a "post-treated" test material. After this, strain relief annealing was further performed at 800″C for 2 hours to obtain a “after strain relief annealing” test material.

As described above, the magnetic properties of each sample material were measured ``before treatment'', ``after treatment'', and ``after strain relief annealing''.

As is clear from the examples shown in Tables 3 and 4, even if strain relief annealing is performed after magnetic domain refining, the iron loss improving effect is not lost, and a oriented electromagnetic copper plate with extremely low iron loss is provided.

(Effects of the Invention) As explained above, according to the present invention, the iron loss of the steel plate is reduced by magnetic domain refining by the intruder, and after that,
It has an excellent feature not seen in previous magnetic domain refining methods, in that the iron loss improvement effect does not disappear even when strain relief annealing is performed at high temperatures.

[Brief explanation of drawings]

FIG. 1 is a metal micrograph (xlooo) showing an intruder formed in a steel plate according to the present invention.

Claims (1)

[Claims] 1. Surface coatings such as glass coatings and insulating coatings are removed from a finish-annealed grain-oriented electrical steel sheet, and strain is applied before and/or after forming a penetrable body coating on the steel plate. 1. A method for producing an ultra-low core loss grain-oriented electrical steel sheet, which comprises heat-treating the steel sheet to form intruders different from the steel composition or steel structure at intervals, thereby refining magnetic domains. 2. Remove surface coatings such as glass coatings and insulating coatings from a finish-annealed grain-oriented electrical steel sheet at intervals, and then apply strain before and/or after forming a penetrable body coating on the steel sheet; A method for producing an ultra-low iron loss grain-oriented electrical steel sheet, which comprises heat-treating the steel sheet to form interstitial bodies having different steel composition or structure at intervals, thereby refining magnetic domains.