JPS62133021A - Grain oriented electrical steel sheet having good adhesiveness of glass film and low iron loss and production thereof - Google Patents

Abstract

PURPOSE:To produce a grain oriented electrical steel sheet having good adhesiveness of a glass film and low iron loss by forming sharp and fine ruggedness on the surface of a rolled steel sheet of a silicon steel and forming an oxide on the surface thereof by decarburization annealing or finish annealing. CONSTITUTION:A silicon steel slab is hot rolled and is annealed, then the slab is subjected to one pass or >=2 passes of cold rolling including intermediate annealing. The rolled sheet is then subjected to decarburization annealing and further a separating agent for annealing is coated on the surface; thereafter, the rolled sheet is subjected to finish annealing. The surface of the steel sheet is activated by a mechanical means such as brush roll or sand blasting in such a manner that the sharp and fine ruggedness exists on the surface of the steel sheet before or after the above-mentioned decarburization annealing. The oxide essentially consisting of SiO2 partially plunged to the base iron side of the steel sheet by the decarburization annealing or finish annealing is thus thereby formed. The above-mentioned oxide forms the glass film having the good adhesiveness by reacting with the above-mentioned separating agent for annealing in the finish annealing. The above-mentioned film applies large tension to the steel sheet and the grain oriented electrical steel sheet having extremely low iron loss is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a force-oriented electrical conductor plate with good adhesion to glass and low stiffness, and a method for manufacturing the same.

[Conventional technology]

Grain-oriented electrical steel sheets are used as cores for electrical equipment such as transformers and generators, but it is important that they have good magnetic properties such as core loss and excitation properties, and excellent glass coating properties.

Normally, grain-oriented electrical steel sheets are made by hot rolling a silicon steel material containing 4% or less of Si, hot rolling pre-annealing as required, and cold rolling to the final finishing thickness through one or two cold rolling steps. After obtaining the plate and then decarburizing annealing, an annealing separator mainly composed of HO is applied and final annealing is performed to develop secondary recrystallized grains with Goss orientation, and further S, N It is manufactured through a process of removing impurities such as and forming a glass film, followed by flattening stress-relieving annealing and insulation coating treatment.

By the way, among the 11 characteristics of N steel plate, directional electric current is also
Improvements in 11 properties and modifications to the glass film have been investigated. For example, in order to lower the steel armor, it is effective to reduce the thickness of the grain-oriented electrical steel sheet or make the crystal grains smaller.J, App1, Phys.

Egg, (1967), 1104-1108. However, if the plate thickness becomes thinner than a certain value, the current consumption increases rapidly and the iron loss increases.Therefore, there is a limit to the reduction in iron loss due to the thickness of the plate jγ.

Furthermore, when the plate thickness becomes thinner, there arises a problem that secondary recrystallization becomes poor.

In addition, since grain-oriented electrical steel sheets sufficiently exhibit secondary recrystallization and grow crystal grains with Goss orientation, improving excitation characteristics and iron loss characteristics, There is also a limit to the reduction in iron loss.

Regarding the improvement of glass film, for example, Japanese Patent Application Laid-Open No. 50-715
In 26, the surface layer of a grain-oriented electrical steel sheet that has been cold rolled to the final thickness is 3 g/m before decarburization annealing.
Pickling is carried out to remove surface deposits and the surface layer of the steel, allowing the decarburization reaction and oxide formation reaction to proceed evenly, and after decarburization annealing, an annealing separator is applied, and final annealing is performed. It is described that a MHOSiO□-based insulating film with good uniformity and adhesion is formed by applying the following steps.

Furthermore, in JP-A-57-101673, after decarburizing a grain-oriented electrical steel strip that has been cold-rolled to an R end plate thickness, an annealing separator such as MgO is coated on one side of the surface of the steel strip. .0
25~0.5 g/rd is removed by grinding or pickling to remove the oxide film on the surface layer of the copper plate, then apply an annealing separator and finish annealing to provide good adhesion and a uniform gray appearance. It is described that a glass film is formed.

[Problems that the invention attempts to solve]

Through these efforts, improvements have been made in film properties such as adhesion of glass films, and improvements have also been made in magnetic properties, but this is not sufficient, and further studies will be conducted to improve these properties. It is hoped that efforts will be made to improve this.

The present invention was completed as a result of various experiments and studies, with the aim of providing a 6fl steel plate with improved adhesion of the glass film, enhanced tension effect, and low iron loss.

[Means for solving problems]

As a result of the study, the present inventors found that by forming oxides that partially penetrate into the steel sheet substrate side, it produces an anchor effect and improves the adhesion of the glass film by a factor of 11. It was discovered that the tensile effect was dramatically improved and grain-oriented electrical steel sheets with low iron loss could be obtained.

The present invention will be explained in detail below.

The present inventors discovered that the oxide layer formed on the surface of the steel sheet during decarburization annealing,
The effects of the morphology of the glass film formed by the reaction between the oxidized layer and the annealing separator on the adhesion of the glass film, tension on the steel plate, and iron loss were investigated. Hereinafter, the layer formed on the steel sheet side by F/ in such a process and made of SiO□-rich Fe11 oxide, normal oxide, or oxide partially containing forsterite will be referred to as an internal oxidation layer. In this experiment, the surface of a cold-rolled grain-oriented electrical steel sheet that had been cold-rolled to an end-plate thickness of 0.225 mm was polished using different sandpapers on the set to form sharp and fine irregularities. Then, decarburization annealing was performed to change the depth and morphology of the internal oxidation layer formed on the steel sheet. Thereafter, an annealing separator containing MgO as a main component was applied and final annealing was performed.

As shown in Figure 1 (B), the internal oxide layer was formed to a uniform thickness in the unpolished layer, whereas it was formed in the polished layer as shown in Figure 1 (A). It was partially formed deeper than the average thickness by penetrating into the base steel side of the steel plate. After applying an annealing separator and finishing annealing, the adhesion of the glass film was tested at lQm, which is more severe than the normal test conditions of 20 to 50 long φ bending.
The results of IAI inspection by sφ bending and peeling area ratio are
As shown in the figure, samples (A) and (B), in which the internal oxidation layer was formed by partially penetrating the base metal side, did not peel off and had extremely good adhesion. Furthermore, the tension applied to the steel plate was greatly improved as shown in Figure 3. As shown in Figure 4, it was found that the iron loss was significantly reduced and a low iron volume ratio was achieved.

In the case where the internal oxidation layer was formed deeply, the glass film was similarly formed deeply during final annealing.

The oxide is partially on the base metal side of the steel plate from the average thickness by 2 to 1
The depth of penetration is preferably about 5 μm. Here, the term "partial" refers to a state in which the oxide is discontinuous or continuous, with protrusions appearing at non-uniform intervals or regular intervals.

Next, a method for manufacturing a grain-oriented electrical steel sheet according to the present invention will be described.

It is not necessary to specify the steel composition of grain-oriented electrical steel sheet and the manufacturing conditions until cold rolling. For example, C is 0.04 to 0.
．． 10%, Si 2.0-4.0%, AIN, MnS, MnSe, BN, Cu as inhibitors
An appropriate material such as zS is used, and if necessary, Cu,
Sn, Cr.

Contains elements such as Ni, 'Mo, and Sn. An electromagnetic steel slab is hot rolled, annealed, and then cold rolled once or twice or more with intermediate annealing to achieve a desired final thickness.

Next, before or after decarburization annealing, the surface of the steel sheet is treated by appropriate means such as mechanical processing using brush rolls, sandpaper, a grinder, shot blasting, etc. so that Ge+-rich and fine irregularities are present on the surface of the steel sheet. Activate.

By activating the steel plate surface, a thick 5i02-rich oxide film is formed during decarburization annealing or finish annealing. This S
In, when the main oxide film is formed thickly, the glass film formed by the reaction with the annealing separator becomes thick and of good quality.

The above-mentioned unevenness is formed on the surface of the steel sheet by decarburizing annealing or finish annealing, which locally promotes chemical reactions such as oxidation on the steel sheet base iron side, and partially penetrates into the f plate base iron side from the average thickness. This is to form an oxide.

The above-mentioned sharp and fine irregularities are provided on one or both sides of the steel plate over the entire surface, for example, at least 35% of the surface area of the steel plate. Further, the depth of the unevenness is desirably about 2 to 15 μm. The unevenness may be provided in any direction.

Decarburization annealing is preferably carried out at a dew point of 60 to 70°C or higher in the case of an atmosphere of 225% N2 and 75% H2 at 850°C.

After decarburization annealing, TiO□ with MgO as the main component.

An annealing separator containing additives such as compound B, SrS, SnS, and CuS is applied, dried, and final annealing is performed.

During the final annealing, the annealing separator reacts with the oxide formed during the decarburization annealing, which partially penetrates into the steel plate substrate from the average thickness, to form a glass film.

In addition, if the sharp and fine irregularities are formed on the surface of the steel sheet after decarburization annealing, oxides partially penetrate into the steel sheet base side are formed during final annealing, and a glass film is also formed. .

The glass coating has very good adhesion because it is connected to the oxide that is partially deeply penetrated into the steel plate base metal side, or because it is also partially deeply penetrated. Further, the tension that the film imparts to the steel sheet is as large as 111, and a steel sheet with extremely low core loss can be obtained.

Thereafter, if necessary, the steel plate is flattened and annealed, and the steel plate is treated with phosphoric acid, phosphates such as aluminum phosphate, nium phosphate, magnesium phosphate, zinc phosphate, calcium phosphate, chromic acid, chromate such as magnesium chromate, etc. -acid acid, dichromate,
An insulating film solution containing one or more types of colloidal silica is applied and baked at a temperature of 350° C. or higher to form an insulating film.

〔Example〕

Next, examples will be shown.

<Example 1> C in weight%: 0.065. Si: 3.25.
Mn: 0.068°Aff: 0.027.
S: 0.023. Cu: 0.0? ,
Sn: 0.1.2 A silicon steel slab consisting of the balance iron is hot-rolled, annealed and cold-rolled to 0.0 by a well-known method.
A steel plate with a thickness of 25 mm was obtained, and this was used as a test material before treatment.The steel plate was coated with unevenness of 12 μm, 9 μm, 1 pm, 5 μm, and 3 μm in surface roughness by changing the illumination of sandpaper. Polishing was performed so that the area ratio of the formed treated area was 50%.

Next, after carrying out each process of decarburization annealing, application of annealing separator, and final annealing, the film properties and magnetic properties of the finished plate, which was subjected to insulation coating application and heat flattening, were determined by J.
It has been decided. The results are shown in Table 1.

In addition, in the investigation of film adhesion, two of the normal bending conditions were used.
In the case of 0 to 50 negative φ, the condition was good without any peeling, including the untreated I material, so even more severe bending conditions 10
I went with Ryuφ.

Table 1 <Example 2> C in weight %: 0.060. Si: 3.15.
Mn: 0.070°Al: 0.030.
S: 0.024. Cu: 0.07.
A silicon steel slab consisting of Sn: 0.13% and the balance iron was treated and cold rolled in the same manner as in Example 1 to obtain a steel plate with a thickness of 0.29 mm. The steel plate is blasted with a square shot to a depth of 25 to 1. oI! The treatment was performed so that the area ratio of the shot-treated portion was 80% or more with an unevenness of m.

Next, after carrying out the steps of decarburization annealing, application of an annealing separator, and final annealing, the film properties and magnetic properties of the finished plate, which was subjected to insulation coating application and heat flattening treatment, were investigated. The results are shown in Table 2.

Table 2 <Example 3> Weight % C: 0.05B, Si: 3.10.
Mn: 0.065°A1: 0.0010
．． S: A silicon steel slab consisting of 0.024% iron was cold-rolled twice by a well-known method to obtain a steel plate with a thickness of 0.265 mm, and this was used as a 4R sample of "Before Treatment 1".

The surface roughness of the steel plate is 3 to 4 μm using a brush roll.
5~61tm, 8~10/Jm, 12~
The surface area of the steel plate with an unevenness of 15/jm is approximately 7.
Polishing was performed so that it became 0%.

Next, after carrying out each process of decarburization annealing, annealing separation agent application, and final finish annealing, the finished plate was coated with an insulation coating and heat flattened.

The properties and magnetic properties were measured. We also measured the tension of the glass film before insulating coating treatment. The results are shown in Table 3.

Table 3 (Example 4) A cold-rolled plate with a thickness of 0.225 am prepared in the same manner as in Example 1 was heated in a humid atmosphere containing 25% N2 and 75% N2.
A test material was decarburized and annealed at 50°C for 3 minutes. This decarburized plate was brushed to a steel plate surface roughness of 12 to 15 μm.

Polishing was performed so that the area ratio of the treated portions at depths of 8 to IQμ, 4 to 6μ, and 2 to 3μ was approximately 50%.

Next, after applying an annealing separator, final annealing was performed at 1200° C. for 20 hours, and the magnetic properties of the finished plate, which had been subjected to insulation coating and heat flattening, were measured. The results are shown in Table 4.

Table 4 (According to the present invention, as can be seen from the above examples,
A grain-oriented electrical steel sheet with poor film adhesion and extremely low tLtM can be obtained.

[Brief explanation of drawings]

Figures 1 (A) and (B) are metallurgical microscopic photographs showing examples of internal oxidation layers formed on the surface layer of steel sheets according to the present invention and comparative examples. Figure 2 is the effect of internal oxidation on the adhesion of glass coatings. Figure 3 shows the effect of the depth of penetration of the internal oxide layer on the tension on the steel plate. Figure 4 shows the depth of penetration of the internal oxide layer that does not affect iron loss. FIG.

Claims (1)

[Claims] 1. In a grain-oriented electrical steel sheet on which a glass film is formed,
A grain-oriented electrical steel sheet with good adhesion of a glass film and low iron loss, characterized by forming oxides that partially penetrate into the steel sheet base iron side. 2. Hot-rolling a silicon steel slab, annealing it once, or cold-rolling it twice or more with intermediate annealing in between to decarburize it;
In a method for manufacturing grain-oriented electromagnetic copper plates in which an annealing separator is applied and then finish annealing, sharp and fine irregularities are formed on the steel plate surface to activate the steel plate surface before or after decarburization annealing, and decarburization or finish annealing is performed. A method for producing a grain-oriented electrical steel sheet with good adhesion of a glass film and low iron loss, characterized by forming oxides that partially penetrate into the steel sheet base iron side.