JPS61117284A - Production of low-iron loss grain-oriented electromagnetic steel sheet - Google Patents

Abstract

PURPOSE:To develop a low-iron loss grain-oriented electromagnetic steel sheet which decreases the deterioration of the magnetic characteristic owing to stress relief annealing by removing part of the base iron of the grain-oriented electromagnetic steel sheet subjected to finish annealing or formed with an insulating film after the finish annealing then subjecting the steel sheet to a phosphoric acid tensed film treat ment. CONSTITUTION:The grain-oriented electromagnetic steel sheet formed by subjecting a silicon steel slab contg.<4% Si to hot rolling, cold rolling and secondary recrystallization annealing or further coating of an insulating film thereon and baking of the coating is marked off to the wire- or spot shape at 5-10mm intervals, 0.1-0.4mm width, 0.02-0.1mm depth and <=0.3mm inter-spot distance or is irradiated with laser light to the insulating film by which the insulating film is stripped and part of the base metal is removed. A metal is plated to the part from which the base iron is removed and thereafter said part is subjected to the phosphoric acid tensed film treatment, by which the low-iron loss grain-oriented electromagnetic steel sheet without having the deterioration of the magnetic characteristic owing to the stress relief annealing is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing a grain-oriented electrical steel sheet with low core loss and whose magnetic properties hardly deteriorate even when subjected to strain relief annealing.

(Prior Art) In grain-oriented electrical steel sheets, it is important to reduce iron loss from the viewpoint of energy conservation. As a method for reducing iron loss, a method of subdividing magnetic domains by laser irradiation has already been disclosed in Japanese Patent Application Laid-Open No. 58-26405. This is caused by Therefore, it can be used for laminated core transformers that do not require strain relief annealing, but cannot be used for wound core transformers that require strain relief annealing.

Furthermore, Japanese Patent Application Laid-Open No. 56-130454 discloses a method of reducing iron loss by utilizing fine crystal grain groups produced by the annealing when a strained steel plate is subjected to secondary recrystallization annealing. This method uses fine recrystallized grains generated on the surface of the steel sheet to reduce the iron loss value, so the iron loss value does not deteriorate due to strain relief annealing. It's difficult to obtain.

(Problems to be Solved by the Invention) This invention solves the problem that although a low core loss value can be obtained by laser irradiation technology as described above, strain relief annealing cannot be performed, and by the fine recrystallized grain generation technology. We developed a method for manufacturing unidirectional electrical steel sheets with low iron loss that has the advantage of not degrading magnetic properties even after strain relief annealing, but at the same time solves the problem of insufficient improvement of magnetic properties. This is what we provide.

(Means for Solving the Problems) The present invention solves the problems of the prior art by using a base iron of a finish annealed unidirectional electrical steel sheet or a unidirectional electrical steel sheet subjected to an insulation coating treatment after finish annealing. This problem is solved by a method for producing a low core loss unidirectional electrical steel sheet, which is characterized by removing a portion of the steel sheet and then subjecting the steel sheet to a phosphoric acid-based tension-adding film treatment. The steel is filled with a compound whose thermal expansion coefficient after baking heat treatment is smaller than that of the base steel, thereby reducing magnetic deterioration after strain relief annealing while maintaining magnetic properties at a high level.

The present invention will be explained in detail below.

A silicon steel slab containing 814% or less is heated and hot-rolled to an intermediate thickness, and the obtained hot-rolled sheet is pickled and, if necessary, heat treated at this stage. Next, cold rolling is performed twice or once with intermediate annealing to obtain the final plate thickness, and the obtained cold rolled plate is decarburized and annealed. Thereafter, an annealing separator is applied, and secondary recrystallization annealing is performed to produce a normal grain-oriented electrical steel sheet. An insulating film is applied to the thus obtained steel plate or the steel plate, and a part of the base iron of the baked steel plate is removed.

The method for removing this base metal is to first peel off a part of the insulating film of the steel plate using a method such as scribing that mechanically applies stress to the surface of the steel plate or a method such as radar irradiation, and then remove it using hydrochloric acid or nitric acid. Dissolve and remove the base steel plate with acid such as. Grooves of a desired shape may be formed directly on the base metal by means such as thermal scribing. When grooves are formed on the surface of the steel base with such large stress,
Fine recrystallized grains are generated in the subsequent annealing process, which effectively reduces iron loss.

The shape of the groove for removing the base metal is preferably perpendicular to the rolling direction (<001> direction), but may be oriented at 45° to the rolling direction, for example. It is not preferable to make the slope too large because it will be disadvantageous to reducing iron loss. The present invention is the same as the iron loss value reduction method by laser irradiation in terms of introducing strain, but differs in that strain is locally generated even if strain relief annealing is performed. Therefore, the distance between the grooves in the rolling direction is most preferably 5 to 10 mm as disclosed in Japanese Patent Publication No. 58-26406. The reason for this is that the iron loss value decreases the most within this range. The grooves may be formed as lines or dots, but if they are formed as dots, the interval between the dots should be 0.3 ms.
The following are preferred. If it is larger than this, the effect on reducing the iron loss value will be small.

The relationship between the groove shape 9 width and depth and magnetic properties according to the present invention is as shown in FIG.

Figure 1 (- indicates grooves with a depth of 0.05 vm and various widths formed at 5 mm intervals on a 0.23 tm thick steel plate coated with a phosphoric acid or organic compound for insulation treatment. Then, after applying the above-mentioned phosphoric acid-based tension coating treatment liquid as a compound having a coefficient of thermal expansion smaller than that of the base steel to the groove, 85
The relationship with magnetism as a result of baking treatment at 0°C for 5 minutes is shown.

The above-mentioned phosphoric acid-based tension-adding film treatment is a process in which a coating liquid containing colloidal silica and phosphate as main components is applied and then baked at a temperature of about 350° C. or higher to form a film. In the example shown in Fig. 1, a coating liquid composed of one or more of colloidal silica, aluminum phosphate, chromic anhydride, and chromate salts was used, but the coating liquid is not limited thereto. Various acid salts are used, such as magnesium phosphate or combinations thereof.

In the above example, a coating liquid mainly composed of colloidal silica and phosphate was used as a compound with a smaller coefficient of thermal expansion than the base metal of the steel plate, but instead of this, a coating liquid equivalent to the above coating liquid may be used. Of course, effective coating materials may also be used.

According to Fig. 1(a), the magnetic flux density, one of the magnetic characteristics, decreases as the groove width increases, but if the groove width is made too narrow, the amount of distortion will decrease and the iron loss value will deteriorate.
．． It is necessary that the value be larger than 1■. The upper limit of groove width is 0
．． Good magnetic properties can be obtained up to about 4 ounces.

In Figure 1, grooves with a width of 0.3 m, an interval of 51II+, and varying depths were formed in a steel plate with a thickness of 0.23 m, and the coating liquid was applied so that the grooves were filled with the coating liquid. The results are shown after baking the steel plate at 850°C for 5 minutes.

A groove depth of 0.02- or more is effective in reducing iron loss, and if it is 0.1 w or more, there is little deterioration of the iron loss value, but the magnetic flux density decreases significantly, so the groove depth should be 0.02- or more. A value of 0.1 is preferred.

In this way, in the present invention, after forming a partially removed portion on the surface of the steel plate substrate, the thermal expansion coefficient (approximately 13×10 ) of the steel plate substrate is
A compound having a smaller coefficient of thermal expansion, such as a coating liquid as described above, ie, a phosphoric acid-based tension coating treatment liquid, is applied to the steel plate so that the removed portion is filled. Here, the entire surface is coated because it is easier from an industrial perspective than the local coating, but it goes without saying that the same effect can be obtained by local coating. The filling method may be any method such as coating.

Furthermore, the effect can be further enhanced by metal plating the removed part of the base metal in order to increase the bonding strength between the filler and the base metal. In the case of the above solution containing colloidal silica, the N
L plating is effective in increasing the bonding strength between the filler and the base.

FIG. 2 is a photographic diagram showing the results of magnetic domain observation using a scanning electron microscope. This sample corroded in a nitric acid solution after irradiating an electrical steel sheet with a tension coating, and the result was approximately 0.02
A 5m deep hole was created and a coating solution consisting of aluminum acid, colloidal silica, and chromic acid was heated at 350°C.
After baking, it was heat treated in the air at 850°C for 2 minutes, and strain relief annealed at 850°C for 4 hours. It is clearly observed that magnetic domains are generated from the holes. . In this way, it is thought that the filler generates magnetic domains in the rolling direction and subdivides the magnetic domains to reduce the iron loss value.

Here, with the aim of manufacturing products in the most economical way, we have explained steel sheets that have been subjected to annealing or an insulating coating such as a phosphoric acid coating, but secondary recrystallization that has no coating at all has been explained. Even if the treatment of the present invention is applied to a steel plate that has undergone finish annealing (finish annealed steel plate), the effect of reducing the iron loss value can be expected.

Examples of the present invention will be described below.

(Example) Example 1 One-time cold rolling method! l A finish annealed unidirectional electrical steel sheet finished to a thickness of 0.23 m was scored with the tip of a knife in the form of straight grooves at 5-tone intervals perpendicular to the sheet rolling direction, to a depth of approximately 0.03 m on the base metal. A groove with a width of 0.2 tW and a width of 0.2 tW was formed. Then 100% colloidal silica 20% aqueous dispersion
cc, aluminum phosphate 50% aqueous solution 60 cc
, apply a coating liquid with a composition of 6 g of chromic anhydride,
It was baked at 830°C for 3 minutes. It was further subjected to strain relief annealing at 850°C for 4 hours.

The iron loss value in the rolling direction of the steel sheet before and after strain relief, and the steel sheet that was strain relief annealed with only a phosphoric acid-based tension film applied after final annealing, and the 5W steel plate after final annealing and after applying a phosphoric acid-based tension film. Table 1 shows the iron loss values in the rolling direction of steel plates that were annealed to relieve strain by scoring grooves with a depth of about 0.03 and a width of 0.2 at intervals.

Table 1 As can be seen from Table 1, the iron loss decreases even with only scribing, as fine grains are generated in the secondary recrystallized grains, but according to the present invention, finishing annealing + applying a phosphoric acid tension coating reduces the iron loss. The iron loss value is 0.1 mm at Wj 715G, ~0.13 W/
The iron loss value has decreased by 0.03 to 0.05 W/kII, which is comparable to the iron loss value of a steel plate that has been annealed to remove strain after scoring. This shows that filling with tensioning material is effective.

Example 2 A phosphoric acid-based tension coating was applied to the finish annealing coating of a grain-oriented electrical steel sheet with a thickness of 0.23 m produced by a single cold rolling method, and a steel plate surface coating was applied to the surface coating of the steel plate using a Yagra day with a pulse intensity of approximately 4 mJ. Peeling occurred in dotted lines perpendicular to the rolling direction at intervals of 2 swφ and 0.3+w.

The distance between the lines was 5 m. After peeling, it was immersed in 61 cm of nitric acid for 20 seconds to form a hole with a depth of about 0.04+ m. After that, Wa t t @ bath (Sulfur El 2y Kel 2401mm
,/l.

Nickel chloride 451mm,/l, boric acid 301! /l
Ni-plating was applied at a current density of 5 A/dm for 5 seconds at a temperature of 60 °C, followed by 100 cc of a 20% water dispersion of colloidal silica, 60 cc of an aqueous solution of aluminum phosphate, 50 cc of aluminum phosphate, and magnesium chromate. Approximately 15 cc of 25% aqueous solution.

Coating liquid with composition of boric acid 3II was applied and heated to 850℃.
Bake for 3 minutes. It was further subjected to strain relief annealing at 800°C for 4 hours. The other one is Ni
It was applied without plating. Table 2 shows the iron loss values of the steel plates in the rolling direction at that time.

Table 2 As is clear from the results in Table 2, the degree of deterioration after strain relief annealing is slightly different depending on whether Ni plating is applied or not, but the iron loss value is extremely superior to that of the conventional method.

(Effects of the Invention) According to the present invention, even if strain relief annealing is performed, a value equivalent to the iron loss value obtained by laser irradiation can be obtained, so the obtained electrical steel sheet can also be used for wound core transformers, and its industrial This is because the electrical steel sheet obtained by the present invention shows a good iron loss value even without strain relief annealing! It has the advantage that it can also be used for R-core transformers.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the relationship between the width and depth of a groove formed in a steel sheet base steel and magnetic properties, and Fig. 2 is a photograph showing the crystal structure of the magnetic domain refinement of the steel sheet of the present invention taken with a scanning electron microscope. It is. Figure 1 (b) At Mizonohara Figure 2 DA/nA Procedural amendment (voluntary) March 7, 1985 Manabu Shiga, Commissioner of the Patent Office, Indication of the case 1988 Patent Application No. 236973 2 , Name of the invention: Method for manufacturing a low core loss unidirectional electromagnetic cylindrical plate 3, Relationship to the case of a person who performs arranging Patent applicant: Nippon Steel Corporation, 2-6-3 Otemachi, Chiyoda-ku, Tokyo (665) Company Representative: Takeshi 1) Yutaka 4, Agent: 2-4-1-5 Marunouchi, Chiyoda-ku, Tokyo 100, Japan Date of amendment order: Month, Day 6, 1939, Column 7 for detailed description of the invention in the specification to be amended , Contents of the amendment (4 lines from the bottom of page 5 of the specification ``Reduce the decreasing J''
Correct to. (2) On page 8, line 1, “preferable.” should be changed to “preferable.”
Even when the depth of the groove is 0.01 m1 or more, the magnetic properties are improved compared to the conventional method. ”. Procedural amendment (voluntary) July 2, 1985 Manabu Shiga, Commissioner of the Patent Office 1, Indication of the case
Kikaru Patent Application No. 236973 of 1982 2, Title of invention: Method for manufacturing low iron loss unidirectional electrical steel sheet 3, Relationship with the person making the amendment case Patent applicant: 2-6-3 Otemachi, Chiyoda-ku, Tokyo No. (665) Nippon Steel Corporation Representative Takeshi 1) Yutaka 4, Agent 〒100 6 Subject of amendment IfI 4 of the claims of Meikisho and detailed description of the invention (1) Attach the claims Correct as shown. (2) Five lines from the bottom of page 5 of the specification “5~lQawJ”.
Correct to 5-10 alJ. (3) After "We can expect it." on page 9, line 14, insert "The magnetostrictive properties after strain relief annealing were the same as those of normal materials." (4) Same page 12, 1mm, line “in nitric acid” changed to “in nitric acid (2
5℃). (5) In Table 2 on page 13, "Process" on the left side of the top column has been amended to "Category." A low iron loss unidirectional electrical steel sheet characterized by removing a part of the base iron of the unidirectional electrical steel sheet which has been subjected to an insulation coating treatment after being blunted, and then subjecting the steel sheet to a phosphoric acid-based tension adding coating treatment. manufacturing method. (2) The method according to claim 1, in which a portion of the film on the surface of the steel sheet is peeled off and then pickled. (3) The method according to claim 1, wherein a part of the steel sheet base is removed by applying mechanical means to the surface of the steel sheet. (4) The method according to claim 1, wherein after applying metal plating to the removed portion of the steel plate base metal, a phosphoric acid-based tension-adding coating treatment is performed. (5) The method according to claim 1, wherein the base metal removal portion is formed in a linear or dotted line shape. (6) The distance between the linear or dotted grooves is 2.5 to 10 mm. The width of the groove is 0.1 to 0.43Em, and the depth of the groove is 0.0
6. The method according to claim 5, wherein the volume is 2 to 0.1 gl, and the distance between the points is 0.3 ml or less.

Claims (6)

[Claims] (1) Finish annealed unidirectional electrical steel sheet or after finish annealing,
A method for producing a low core loss unidirectional electrical steel sheet, which comprises removing a part of the base iron of a unidirectional electrical steel sheet that has been subjected to an insulation coating treatment, and then subjecting the steel sheet to a phosphoric acid-based tension addition coating treatment. . (2) The method according to claim 1, wherein a portion of the film on the surface of the steel plate is peeled off and then pickled. (3) The method according to claim 1, wherein a part of the steel sheet base is removed by applying mechanical means to the surface of the steel sheet. (4) The method according to claim 1, wherein after metal plating is applied to the removed portion of the steel sheet base, a phosphoric acid-based tension coating treatment is performed. (5) The method according to claim 1, wherein the base metal removal portion is formed in a linear or dotted line shape. (6) The distance between the linear or dotted grooves is 5 to 10 mm, the width of the groove is 0.1 to 0.4 mm, and the depth of the groove is 0.02 to 0.
．． The method according to claim 5, wherein the distance between the points is 1 mm or less, and the distance between the points is 0.3 mm or less.