JPS6089545A - Grain-oriented silicon steel sheet causing small iron loss - Google Patents

Abstract

PURPOSE:To obtain a grain-oriented silicon steel sheet causing a small iron loss and capable of ensuring the practical effect of the fractionization of the magnetic domain of an article in the lateral direction without deteriorating the characteristic by forming a region where different tensions act on the surface of a steel sheet. CONSTITUTION:An uneven region is formed on the surface of a grain-oriented silicon steel sheet in the rolling direction by a chemical or mechanical means after finishing secondary recrystallization annealing. The steel sheet is then coated and heat treated to apply an elastic strain for different tensions to the surface of the steel sheet by the difference in the coefft. of thermal expansion between the steel sheet and the resulting surface film. The elastic strain can be applied by forming a region having different thicknesses in the insulating film or by other means. The treated grain-oriented silicon steel sheet causing a small iron loss undergoes no deterioration in the characteristics during conventional strain relief annealing.

Description

Detailed Description of the Invention (Technical Field) The technology described in this specification regarding a unidirectional silicon steel sheet with extremely low iron loss reduces strain by forming areas on the surface of the copper sheet where different tension forces act. This is an attempt to create a grain-oriented silicon steel sheet whose magnetic properties do not deteriorate through annealing.

[Technical background]

Unidirectional silicon steel sheets are mainly used as iron cores for transformers and other electrical equipment, and have excellent magnetization characteristics, i.e. iron loss (represented by W 1.7/50).
is required to be low.

For this purpose, firstly, the secondary recrystallized grains in the steel sheet should be
1> It is necessary to highly align grain orientation in the rolling direction, and secondly, it is necessary to reduce as much as possible impurities and precipitates present in the final product. The unidirectional silicon steel sheets manufactured under careful consideration of these points have been improved over the years due to many improvement efforts to date, and recently the sheet thickness has been reduced to 0.80. ms product W1715
Low iron loss products with a zero value of 1.0 s W/9 have been manufactured.

However, after the energy crisis a few years ago, there was a growing trend to install electrical equipment with less power loss.
There is a growing demand for the production of unidirectional silicon steel sheets with even lower iron loss as the iron core material.

(Prior art and its problems) By the way, in order to reduce the iron loss of grain-oriented silicon steel sheets, there are several methods: increasing the S1 content, reducing the thickness of the product sheet, making the secondary recrystallized grains finer, and creating an impurity-containing layer. Mainly metallurgical methods are generally known, such as reducing and aligning secondary recrystallized grains with (], 10) (o 01 ) orientation to a higher degree, but these methods are difficult to achieve with current production methods. It has reached its limit value, and it is extremely difficult to improve it any further, and even if some improvement is recognized, the effective effect of iron loss improvement will be small compared to the efforts made.

Apart from these methods, as disclosed in Japanese Patent Publication No. 54-28647, secondary recrystallization grains are made finer by forming a secondary recrystallization inhibiting region on the surface of the steel sheet. is proposed.

However, this technique cannot be said to be practical because control of the secondary recrystallized grain size is not stable.

On the other hand, Japanese Patent Publication No. 58-5968 discloses that by introducing micro-strain into the surface layer of the steel plate after secondary recrystallization using ballpoint pen-shaped small balls, the width of the magnetic domain is made finer and the iron loss is reduced. Furthermore, the technology to
Publication No. 2 discloses that the width of the magnetic domain is refined by irradiating the surface of the final product plate with a laser beam at numerical intervals almost perpendicular to the rolling direction to introduce high dislocation density regions into the surface layer of the steel plate.
Techniques for reducing iron loss were subsequently proposed, and in JP-A-57-18881'O, a method was proposed in which microstrain was introduced into the surface layer of a steel sheet by electric discharge machining to refine the magnetic domain width and thereby reduce iron loss. Similar technologies have been proposed. All three of these methods aim to reduce iron loss by reducing the magnetic domain width by introducing a small amount of plastic strain to the surface of the base steel of the steel sheet after secondary recrystallization. , equally practical,
It also has an excellent iron loss reduction effect, but the punching process of steel plates,
Shearing, strain relief annealing after winding, and baking of coatings have the disadvantage that the effect of introducing plastic strain is diminished by heat treatment such as G treatment. In addition, if a small amount of plastic strain is introduced after the coating process, the insulation coating must be repainted in order to maintain insulation properties, resulting in a significant increase in the strain imparting process, repainting process, and bowl, increasing costs. bring about.

(Purpose of the Invention) By using a method for refining the magnetic domain width which is different in concept from the above-mentioned prior art, it is possible to ensure the effective refining of the domain width of the product without deterioration of characteristics even after strain relief annealing at high temperatures. It is an object of the present invention to provide a unidirectional silicon steel sheet that can be used.

(History of the elucidation of the solution) The inventors first conducted a new study on the texture and inhibitor dispersion during the manufacturing process of unidirectional silicon steel, with the aim of reducing iron loss.・Decarburization promotion regions and decarburization retardation regions are alternately divided approximately perpendicular to the rolling direction on the steel sheet surface before primary recrystallization annealing or before secondary recrystallization annealing, thus forming heterogeneous secondary recrystallization grains. It was discovered that it was possible to manufacture a new unidirectional silicon steel sheet with lower iron loss by developing
A patent application has already been filed with No. 68.

We conducted a wide range of basic experiments to apply this novel idea of preferentially forming non-uniform secondary recrystallized grains to other process steps.

As one development, after secondary recrystallization annealing of a unidirectional silicon steel sheet, if the magnetic domain width of the product is subdivided by creating zones on the surface of the steel sheet where the actual tension acts, it is possible to significantly It was newly discovered that it is possible to reduce iron loss. Here, the area where actual tension acts on the surface of the steel plate is, for example, the unevenness of the plate surface along the rolling direction obtained by applying something like a chemical polisher in a direction transverse to the rolling direction of the steel plate, and the tension-applying Zetsurin coating. Accordingly, it is possible to form sections so as to generate an actual tension according to the pattern of the unevenness.

(Structure of the Invention) The present invention is a low iron loss unidirectional silicon steel plate characterized by having a region on the surface of the steel plate defined in which actual tension acts.

Next, the process that led to the success of this invention and the basic idea of the invention will be explained.

o O, 0413%, si L35%, Se O
,018%.

A hot-rolled sheet with a thickness of 2.7 was obtained by hot rolling from a steel ingot containing 25% of SbO, 0.013% of MOo. Thereafter, primary cold rolling with a rolling reduction of about 70% was performed after force annealing at 900°C for 8 minutes, and intermediate annealing at 950°C for 3 minutes with a rolling reduction of about 65%.
% secondary cold rolling to obtain a final cold rolled sheet with a thickness of 0.3+wm.

After that, the steel plate surface was degreased and decarburized in wet hydrogen at 820℃.
After the secondary recrystallization annealing, secondary recrystallization annealing was performed at 850° C. for 50 hours and purification annealing in hydrogen at 1200° C. for 5 hours according to a conventional method.

The forsterite coating was then removed with molten IJaOH solution, followed by chemical polishing in 8% HF and H3O2 solution.
Experiments were carried out sequentially in sections ta) to (d) in FIG. 2, which were carried out according to the sections indicated by imaginary lines in the schematic diagram showing the surface of the steel plate.

First, a tensile force T in the rolling direction was applied to sample (a) whose surface had only been chemically polished, and changes in magnetic properties were measured. At that time, the change in magnetic properties depending on the average tensile stress σ is plotted in Figure 3. The other side was coated with vinyl tape and subjected to the chemical polishing described above to create a sample (b) with unevenness on one side approximately 5 to 10 μm deep. Changes in properties were measured, and the results shown in plot (b) in FIG. 3 were obtained.

Next, on the other smooth side of the steel plate, under the same conditions as shown in Figure 2 (b), vinyl tape of 5 widths is sequentially applied at 10 intervals, and on the other side, which is already uneven, vinyl tape is applied to the entire surface. was applied to the ground and chemically polished to form irregularities of approximately 5 to 10 μm. For a sample (0) with unevenness on both sides of the steel plate in this way, the tensile force T
The results of measuring changes in magnetic properties depending on the magnetic properties are also shown in Figure 8 (C).

Finally, in addition to the unevenness on both sides, a sample ((
For No. 11, changes in magnetic properties depending on the tensile force T were measured, and the results are plotted in FIG. 8 (indicated by crests).

Note that FIG. 8 is a plot of the iron loss of each sample after weight correction.

From Fig. 2 and Fig. 8, when a uniform tensile stress is applied to the sample surface in a smooth state, for example, (T, yamamoto t
o IS, Taguch soil + A, 5akakura
and T, Nozawa: 工EEETran, s
; Magt M 8 (1972), P, 67
7) &,: As stated above, iron loss decreases.

Furthermore, since the secondary particle size of this product is as small as 8.5, the degree of decrease in iron loss is 0.08W/7C9 at a tensile stress of 0.2ψ-.
Although it is small, it is noteworthy that when tensile force T is applied to samples (b) and (01) in which one or both sides of the steel plate have unevenness approximately perpendicular to the rolling direction, the iron loss decreases rapidly. When the average tensile stress is 0.2-, the degree of decrease in iron loss at about i is 0.09 WA9 for a single-sided uneven sample with tb).
- It can be seen that the sample (C) with uneven surfaces on both sides has a decrease of 0.11 WAp.

In addition, a sample in which a high dislocation density region was introduced by laser irradiation after roughening both sides of the steel plate (dJ is a sample in which a tensile force T is applied and the iron loss decrease due to laser irradiation is o,
It is noteworthy that although this occurred at about 8 WA9, the iron loss did not decrease much even if the tensile force T was applied thereafter.

The above experimental results are based on the conventionally known method of introducing uniform elastic strain in the rolling direction over the entire surface of the steel sheet (that is, the plot of FIG. 8 according to FIG. A method of introducing a high dislocation density region according to (i.e., the block diagram in Fig. 3 according to Fig. 2(d)) (a)
) rather than the method of introducing elastic strain due to different tension (i.e., the prong in Figure 3 following Figure 2(b), tc))
(bJ (0) ) & iron This shows that it is possible to reduce iron loss extremely effectively. That is,
It has been newly discovered that an effective method for refining magnetic domains can be achieved by introducing elastic strain to the surface of the steel plate by applying different tensions.

Unlike the conventional method of creating high dislocation density regions such as plastic strain regions or laser irradiation marks in the surface layer of the steel, unlike the conventional method of creating γ-oriented silicon steel sheets with such different tensile elastic strain, artificial Since there is no plastic strain region, usually s
There is an advantage that the iron loss does not deteriorate even if strain relief annealing is performed for one minute to several hours around o o 'c.

Conventional methods of creating high dislocation density regions due to plastic strain or laser irradiation marks have the disadvantage that the plastic strain in the surface layer of the steel base disappears at high temperatures, leading to deterioration of iron loss. In this case, good iron loss is shown with or without strain relief annealing.

As is clear from the above explanation of the silicon steel sheet according to the present invention in comparison with a conventional steel sheet, the present invention is essentially different in concept from the prior art, and will be verified later with examples. The effect is also much better.

Next, the material and manufacturing process of the silicon steel plate in this invention will be explained.

First, the starting material is a hot-rolled coil obtained by manufacturing steel by a known steel-making method, such as a converter or electric furnace, and then converting it into a slab by ingot-forming or continuous casting, followed by hot rolling.

The composition of this hot rolled sheet is the same as that of conventionally known unidirectional silicon steel sheets, for example, ■Si 2-0-4.0%.

MO0,005~0.05%, SbO,005
~0.25%.

Silicon steel plate containing S or se o, o o 5 to 0.05%, ■si 2.0 to 4.0%, i (1
,01~0.05%,SO,005~0.05
%, silicon steel plate containing NO,001-0.01% or ■st 2.0-4.0%.

SO, 005~0.05%, BO, 0008~0
．． It is also applicable to silicon steel sheets containing 0.040%+No.001 to 0.01%.

Hot-rolled sheets are either uniformly annealed at 800°C to 1100°C and then cold-rolled once to achieve the final thickness, or they are usually subjected to intermediate annealing at 850°C to 1050°C before being rolled. The reduction rate is about 50% to 80%, the final reduction rate is 50%.
0.2 in either of the two-step cold rolling methods at a rate of about 80% from
It can be cold-rolled twice to give a final thickness of about 0.85am, but the usual finished thickness is 0.8mt.
After the final cold rolling, the steel plate finished to the product thickness is heated at 750°C to 850°C with wet water concentration.
Decarburization and primary reconsolidation annealing are performed for ~15 minutes.

Thereafter, an annealing separator containing MgO as a main component is applied to the surface of the steel sheet, and final annealing is performed. This final annealing is (IIQ)
This is carried out to sufficiently develop secondary recrystallized grains in the (001) orientation, and is usually performed by box annealing, which immediately raises the temperature to 1000°C or higher and maintains it at that temperature. In order to develop a highly uniform secondary recrystallized structure, it is advantageous to perform retention annealing at a low temperature of 820°C to 900°C;
Heat-removal annealing at a temperature increase rate of ~15''C/11 may also be used.

After this treatment, uneven regions are formed on the surface of the steel sheet at approximately right angles to the rolling direction, and the uneven regions are usually formed at intervals of 1 to 50 mm and approximately half the width thereof. Also, the depth is 1
A thickness of about 20 μm can be sufficiently effective, and such partition formation can be sufficiently effective even on one side, but it is usually more effective to form partitions on both sides of the steel plate. A conventionally known chemical or mechanical method may be used to create the unevenness on the surface of the steel plate.

A tension coating treatment is performed on the steel plate whose surface is thus partitioned into irregularities. This coating process uses a conventional coattender solution for unidirectional silicon steel sheets to
By applying heat treatment at a temperature of 0°C or higher, the coating and baking process width is approximately 800°C to 9 (10°C), and the tension on the steel plate surface is reduced by the difference in thermal expansion coefficient between the steel plate and the surface coating. gives a differentiated tension elastic strain on the surface of the steel plate.

In this way, a unidirectional raw steel plate having different tensile elastic strains on the surface of the steel plate can be obtained, but the same effect can be achieved by other methods other than the above-mentioned method of forming irregularities on the steel plate itself after finish annealing. The method is as follows: (1) A method in which the forsterite-based insulating film formed on the surface of the steel sheet during final annealing is divided into actual regions.

■Method of applying tension coating to ■■Method of forming sections on the surface of the copper plate into areas where forsterite-based insulating film exists and areas where it does not exist.Method of applying tension coating to ■■.

■Method of forming regions with different compositions of the forterite-based insulating coating formed on the surface of the steel plate■Method of applying tension coating to ■Method of forming zones of different phases between the steel plate surface and the 7-orsterite coating .

How to tension coat ■■.

(2) It is also possible to apply a different type of tension coating to the 7-orsterite film on the surface of the copper plate. Both of these methods differ from the conventional method of creating microplastic strain or high dislocation density regions due to laser irradiation marks, by using grain-oriented silicon steel sheets with no plastic strain in the surface layer of the steel, and in addition, they are divided into sections on the surface of the steel sheet. It can be used to create unidirectional flexural plates with different tensile elastic strains.

(Effects of the Invention) Thus, the present invention provides a low iron loss unidirectional silicon steel sheet which has a remarkable effect that properties do not deteriorate during normal strain relief annealing.

Next, the present invention will be explained with reference to examples.

EXAMPLE After equalization annealing at 900°C for 8 minutes, cold rolling was performed twice with intermediate annealing at 950°C to obtain a final cold-rolled plate with a thickness of 0.3. Thereafter, decarburization and primary recrystallization annealing were performed in wet hydrogen at 820°C, followed by secondary recrystallization annealing at 850°C for 50 hours and blunting annealing at 1180°C for 5 hours.

Thereafter, the surface of the steel plate was removed approximately perpendicularly to the rolling direction at 10 mm intervals in a width of 5 mm at a depth of approximately 5 μm within the steel base, and then 100 cc of an 80% aqueous dispersion of colloidal silica, 80 cc of a 40% magnesium phosphate solution, and PM acid anhydride 89
and dichromium 111.59, and baked this in the atmosphere at 800° C. for 1 minute to form an insulating film.

The magnetic properties of the product at that time were as follows.

Bl(1=1-91 T*W1?150=0
．． 9 a vJAcg, Example 2 00.048%, S13.26%! Acid soluble A) 0.02
A hot-rolled sheet (2.9+m thick) containing 5% I SO, 018% + N O, 0,062% was uniformly annealed at 1050°C, then rapidly cooled, and cold-rolled once. The final cold-rolled sheet with 8-thickness was made. Note that during the cold rolling, warm rolling was performed at 850°C. After that, decarburization and primary recrystallization annealing were performed in wet hydrogen at 800°C, followed by secondary recrystallization by raising the temperature from 850°C at 5°c/hr, followed by purification in hydrogen at 1200°C for 5 hours. Annealed. Thereafter, the surface of the steel plate was removed approximately perpendicularly to the rolling direction at a depth of approximately 4 μm within the steel base with 4 widths at intervals of 8 strokes, and then 100 cc of a 20% aqueous dispersion of colloidal silica was removed.
, aluminum phosphate 50% aqueous solution a occ % m
It was treated with a coating solution having a composition of 6 parts of water, 6 parts of romic acid and 2 parts of boric acid, and this was baked in the air at 800° C. for 2 minutes to form an insulating film.

The magnetic properties of the product at that time were as follows.

B, o = 1.98 T I W, /, o = 0.97
WAC9

[Brief explanation of the drawing]

Fig. 1 is a plan view showing a partial surface of a steel plate after finish annealing, Fig. 2 (a) to (d) are schematic views of cross sections of steel plates subjected to various chemical polishing, and Fig. It is a chart showing the change in magnetic properties depending on the average tensile stress of each sample of (a) to (d) in the figure. Patent ff Applicant Kawasaki Steel Co., Ltd. Patent Attorney Ko Sugimura S゛゛''゛) 1, Figure 1, Figure 2 (a) Tensile Stress (Kμm Procedural Amendment (Method) % Formula % 1, Case Indication of 1981 Patent Application No. 196191 2, Title of invention: Low core loss unidirectional silicon steel sheet 3, Person making amendments Relationship to the case Patent applicant (125) Kawasaki Steel Corporation (5925) Patent attorney Sugimura Xiao Xiu Gai 1 person 5, Date of amendment order January 31, 1980 6. Details subject to amendment Yang, ``Brief explanation of drawings'' column, ``
Drawing j-1-1, lines 4 and 5 on page 18 of the specification are corrected as follows. "Figures 2 (a) to (C) are schematic diagrams of cross sections of steel plates that have been subjected to various types of chemical polishing, and Figure 2 (d) is a schematic diagram of a cross section of steel plates that have been further irradiated with laser on the uneven areas caused by chemical polishing. ,'' 2. In the drawings, Figure 2 (a'l, (b), (Cri, (1) is corrected as shown in the attached sheet.

Claims (1)

[Scope of Claims] 1. A unidirectional silicon steel sheet with low iron loss, characterized by having regions on the surface of the steel sheet where different tensions act. 1. The unidirectional silicon steel plate according to 1, wherein the steel plate does not have a plastic strain region in its base metal surface layer.