JPH0663038B2 - Manufacturing method of grain-oriented silicon steel sheet with low iron loss, whose characteristics are not deteriorated by strain relief - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) With regard to a method for producing a grain-oriented silicon steel sheet having a low iron loss, the technical content described in this specification is not particularly applicable to a surface layer portion of a base steel including a coating film on the steel sheet surface. This is related to improving iron loss by imparting uniformity and partitioning and forming a region where different tension acts or a region where magnetic permeability is discontinuous on the surface.

It is mainly used as an iron core for transformers and other electrical equipment of grain-oriented silicon steel, and has excellent magnetization characteristics.
Especially, low iron loss (represented by W _17/50 ) is required.

To this end, firstly, the secondary recrystallized grains in the steel sheet <001>
It is necessary to highly align the grain orientation with the rolling direction, and secondly, it is necessary to reduce impurities and precipitates existing in the final product steel as much as possible. Iron loss value of _grain- oriented silicon steel sheet manufactured under such consideration has been improved year by year through many improvement efforts, and recently, the value of W _17/50 is 0.30 mm in product and the value of W _17/50 is improved. Low iron loss of 1.05w / kg is obtained.

However, since the energy crisis of several years ago, the tendency to seek electrical equipment with less power loss has become stronger, and grain-oriented silicon steel sheets with even lower iron loss are required as iron core materials for these. It has become.

(Prior Art) By the way, as a method of reducing the iron loss of a grain-oriented silicon steel sheet, the Si content is increased, the product sheet thickness is reduced, the secondary recrystallized grains are fined, the impurity content is reduced, And metallurgical methods are generally known, such as making secondary recrystallization of (110) [001] orientation more advanced, but these methods are no longer available from the present production means. It has been reached, and further improvement is extremely difficult, and even if a small number of improvements are recognized, the effect of iron loss improvement is small for the effort.

In addition to these methods, as disclosed in Japanese Patent Publication No. 54-23647, a method is proposed in which secondary recrystallized grains are formed into fine particles by forming a secondary recrystallization inhibiting region on the surface of a steel sheet. Has been done. However, this method is not practical because the control of the secondary recrystallized grain size is not stable.

In addition, in Japanese Patent Publication No. 58-5968, by introducing a minute strain into the surface layer of the steel sheet by a ball-point pen-shaped small ball on the surface of the steel sheet after secondary recrystallization, the width of the magnetic domain is made fine and the iron loss is reduced. According to the technology, in Japanese Patent Publication No. 57-2252, a laser beam is applied to the surface of the final product plate at a substantially right angle to the rolling direction.
A technique has been proposed in which the width of a magnetic domain is miniaturized and the iron loss is reduced by irradiating the surface of the steel sheet with a high dislocation density region by irradiating it with a space of mm.

Further, Japanese Patent Application Laid-Open No. 57-188810 proposes a similar technique in which a minute strain is introduced into the surface layer of a steel sheet by electric discharge machining to make the magnetic domain width finer and reduce the iron loss.

(Problems to be Solved by the Invention) In all of these three types of methods, a small plastic strain is introduced into the surface layer of the base metal of the steel sheet after secondary recrystallization to reduce the magnetic domain width and reduce iron loss. It is even, practical, and has an excellent iron loss reduction effect, but it can be processed by stress relief annealing after punching, shearing, winding, etc. of steel sheets and heat treatment such as baking treatment of coatings. ,
This is accompanied by the drawback that the effect of introducing plastic strain is diminished. If a small amount of plastic strain is introduced after the coating process,
Insulation coating must be re-applied in order to maintain the insulating property, resulting in a large number of steps such as a strain imparting step and a re-applying step, resulting in a cost increase.

This invention can secure the effect of the magnetic domain subdivision of the product without the characteristic deterioration even after the strain relief annealing at a high temperature by the magnetic domain width subdividing means having a different idea from the above-mentioned prior art. The purpose is to provide a grain-oriented silicon steel sheet.

(Means for Solving the Problem) The present invention is that the foreign matter having a composition different from that of the ground iron locally exists in the ground iron surface layer portion of the grain-oriented silicon steel sheet coated with the forsterite coating, It contributes extremely advantageously to the subdivision of the magnetic domain width of the product, and when a tension-type insulating coating film is laminated on the forsterite film in the presence of such a foreign substance, the combined action of the two causes the desired effect. Based on the new finding that the effect achieved is further promoted.

In the manufacturing process of grain-oriented silicon steel sheet, the steel sheet cold-rolled to the final plate thickness is usually subjected to decarburization annealing to remove harmful carbon. By such annealing, the steel sheet becomes a primary recrystallization texture containing a finely dispersed second phase inhibitor inside, but at the same time, the steel sheet surface layer is a subscale in which fine SiO ₂ particles are dispersed in the base steel. It becomes a structure. This decarburized / primary recrystallized plate is subjected to a secondary recrystallization annealing, followed by high temperature purification annealing at about 1200 ° C., after applying an annealing separator containing MgO as a main component on the surface thereof. By this secondary recrystallization annealing, the crystal grains of the steel sheet become coarse grains of (110) [001] orientation. Further, S, Se, N, etc., which are a part of the inhibitor existing inside the steel sheet, are removed to the outside of the steel sheet base metal by the high temperature purification annealing.

Further, in this purification annealing, SiO ₂ in the subscale of the iron plate surface layer and MgO in the annealing separator applied to the surface are reacted as in the following formula, 2MgO + SiO ₂ → Mg ₂ SiO ₄ On the surface, forsterite (Mg ₂ S
A film made of polycrystalline iO ₄ ) is formed. At this time, the surplus MgO plays a role of preventing fusion between the steel plates as an unreacted material. Then, the steel sheet that has undergone high-temperature purification annealing is subjected to a treatment for removing unreacted annealing separating agent and removing, and if necessary, removing the overcoat of the insulating coating and the coil set to obtain a product.

By the way, as a result of re-examination of the role of the forsterite coating, the inventors have found that this coating applies tension to the steel sheet to subdivide the magnetic domains, like the tension-imparting coating.
Moreover, it was found that the subdivision effect of the magnetic domain width of the steel sheet differs slightly depending on the location. Therefore, as a result of a more detailed study on the tendency of subdivision of the magnetic domain width of the steel sheet, the presence of foreign matter having a composition different from that of the ground iron in the surface layer of the ground iron containing the forsterite coating makes the subdivision of the magnetic domain more effective. Has been achieved.

The present invention is derived from the above findings.

That is, according to the present invention, a hot-rolled sheet obtained by hot-rolling a silicon steel slab is cold-rolled once or twice with intermediate annealing to obtain a final sheet thickness, and then decarburized / decarburized. In the method for producing a grain-oriented silicon steel sheet, which comprises a series of steps in which primary recrystallization annealing is performed, then an annealing separator containing MgO as a main component is attached to the surface of the steel sheet, and then final finish annealing is performed, the annealing separator is used. Prior to the application of, by locally adhering various non-metallic substances or other metals or semimetals other than alkali metals and alkaline earth metals to the surface of the steel sheet, the surface layer of the steel sheet of the steel sheet, Is a method for manufacturing a grain-oriented silicon steel sheet having a low iron loss, in which foreign matter having a different composition is arranged, the characteristics of which are not deteriorated by strain relief annealing.

Further, according to the present invention, a hot-rolled sheet obtained by hot-rolling a silicon steel slab is cold-rolled once or twice with intermediate annealing to obtain a final sheet thickness, and then decarburized. In the method for producing a grain-oriented silicon steel sheet, which comprises a series of steps of performing primary recrystallization annealing, then applying an annealing separator containing MgO as a main component on the surface of the steel sheet, and then performing final finishing annealing, the annealing separator is used. Prior to the application of, by locally adhering various metals or semimetals other than various non-metallic substances or alkali rules and alkaline earth metals to the steel plate surface, Place foreign matter of different composition on the forsterite film,
Low iron that does not deteriorate in properties due to strain relief annealing, which consists of applying a tension-giving type insulation coating treatment liquid exhibiting a thermal expansion coefficient of × 10 ^-6 1 / ° C or less, and then baking it in the temperature range of 600 to 900 ° C. This is a method for producing a loss-oriented silicon steel sheet.

In the present invention, the foreign matter having a composition different from that of the base iron is (i) the same phase as that of the base iron, but it does not exist in the composition in which the amount of other element solid solution is extremely high, and the iron alloy phase (for example, V, Nb, Cr Mo,
(Diffusion phase of substitutional solid solution elements such as Mn, Co, Ni, Cu, Zn, Si and As), (ii) A phase different from base iron, electrostatic coating, plating,
Metals, semi-metals and alloy phases different from the base iron formed by deposition methods such as printing (eg Ni, Cr, Sb, Al, S
n, Ge, Si, Ni-W, Cr-Mo, Fe-W, Sn-Ni, Sn-Co and Ni
-Co), (iii) non-metallic substances such as oxides, carbides, nitrides, borides, phosphides and sulfides (eg Fe, Si, Al,
Oxides such as Ti, Zr and Sb, carbides, nitrides, borides, phosphides, sulfides, etc.), etc.

Further, the arrangement of foreign matter on the surface layer of the steel plate of the steel plate does not refer only to the case where the foreign matter is completely embedded in the ground iron, as shown by a, b, c and d in FIG. , The case where it extends over both the base steel and the forsterite coating, and the case where it exists only in the forsterite coating.

Further, in the present invention, the material steel plate is limited to those in which the plastic strain region is not seen, as described later,
This is because in the method of subdividing the magnetic domain by introducing plastic strain, the characteristics are remarkably deteriorated by the strain relief annealing.

The present invention will be specifically described below.

Now, the inventors experimentally, locally adhere Ni powder as a foreign matter on the steel plate surface during the cold rolling of the grain-oriented silicon steel plate, then continue rolling, the steel plate surface layer portion by a method of completing, A cold rolled steel sheet was prepared by embedding Ni powder as foreign matter.

The cold-rolled steel sheet is subjected to primary recrystallization annealing that also serves as decarburization,
Then, after annealing separation was applied to the surface of the steel sheet, secondary recrystallization and subsequent purification annealing at 1200 ° C. for 5 hours (both are collectively referred to as final finishing annealing) were performed.

As a result, at the place where the Ni powder was embedded in the surface layer of the steel sheet, the steel plate cross section was centered around the point where Ni was embedded, as shown in Fig. 1.
(A) A portion having a composition different from that of the base metal having the shapes shown in (b) and (c) was observed, and it was found that the magnetic domain width of the steel sheet was subdivided at this portion.

Separately from the above method, prior to the application of the annealing separator, Ni powder is locally attached to the surface of the steel sheet as a foreign matter,
After that, when the same final finishing annealing was performed, it was confirmed that the subdivision of the magnetic domains was achieved as in the above case.

Next, the inventors conducted various studies on the arrangement of such foreign matter on the surface layer of the base metal, the influence of the shape and orientation of the foreign matter on the subdivision of magnetic domains, and investigated the relationship with iron loss.

As a result, it was found that the continuous or discontinuous linear form as shown in Fig. 2 (a) is particularly effective for the iron loss reduction effect as the disposition form of the foreign matter on the surface layer of the ground iron. . However, in the discontinuous linear state, the effect decreased when the distance between the points was 0.5 mm or more. In this respect, the iron loss reduction effect was almost the same as in the case of the linear shape even if a part of the line was gradually pulled out like the broken line.

Next, regarding the direction of the linear morphology of foreign matter in the surface layer of the base metal, it is particularly effective to set an angle of 60 to 90 ° with respect to the rolling direction, as shown in Fig. 2 (b) and Fig. 3. Met. The width of the continuous or discontinuous linear form is, as shown in Fig. 4, 0.05 to 2.0 mm, especially 0.8 to 1.5 m.
An excellent effect was obtained in the range of m.

In addition, it is effective to reduce the iron loss of the entire steel sheet that the foreign matter is repeatedly arranged in a direction transverse to the rolling direction. For example, the distance between the regions as shown in FIG. As shown in FIG. 5, it is desirable that the range is 1 mm to 30 mm.

In addition, the effect of the foreign matter was almost the same whether the foreign matter was placed on both sides of the steel sheet or only on one side.

Next, on the forsterite-coated steel sheet in which the above-mentioned foreign matter is arranged on the surface layer of the base metal, after forming the coating, 5 × 10 ^-6 1
Apply a coating liquid that exhibits a thermal expansion coefficient of / ° C,
After baking and applying a tension-imparting insulating coating film, the iron loss was measured, and as shown in FIG. 6, as compared with the case where a foreign substance is simply arranged on the surface layer of the ground iron,
It was found that a further iron loss improving effect was achieved.

Therefore, for various coatings with different thermal expansion coefficients, according to the above-mentioned experiment, I tried to use it on the forsterite coated grain-oriented silicon steel sheet with foreign matter arranged on the surface layer of the base metal, and the thermal expansion coefficient was 9.8 × It was found that a satisfactory iron loss reduction effect can be obtained at 10 ^-6 1 / ° C or less.

Next, the sol of iron oxide was printed by printing the sol of iron oxide on the surface of the cold-rolled silicon-containing steel cold-rolled sheet containing Si: 3.2% to a final sheet thickness of 0.28 mm, in a direction perpendicular to the rolling direction. Linearly to
The width was 0.3 mm, and the repeating interval was 4 mm. Then, according to a conventional method, decarburization annealing was performed, an annealing separator was applied, and then final finish annealing was performed. The iron oxide locally attached to the surface of the cold-rolled sheet reacts with the base iron in the subsequent annealing step, and is present as a foreign substance locally arranged on the surface layer of the base iron.

A steel sheet according to the present invention thus obtained was prepared as A, and a conventional steel sheet having a homogeneous base metal surface layer portion and a uniform and homogeneous forsterite coating was prepared as B for comparison.

At this time, the iron loss of each steel sheet is W _17/50 = 0 for steel sheet A.
99 W / kg, and for steel plate B, W _17/50 = 1.05 w / kg.

Then, the surface of each of these forsterite-coated steel sheets A and B is coated with a tension-imparting top coat coating having a thermal expansion coefficient of 5.6 × 10 ^-6 1 / ° C to form a steel sheet A ',
'Was the iron loss of each steel sheet, steel plate A' B W is about _17/50 = 0.95W / kg, for the same B 'is W _17/50 = 1.04W /
It became kg, and the composite action by the tension imparting coating film of the present invention was confirmed.

Further, with respect to the steel plate B ′, the coating and the forsterite are volatilized together by using the irradiation of the pulse-shaped high power laser beam, which is a conventionally known iron loss improving method, to form a series of dots (dots and dots). A region with a spacing of 0.4 mm) was formed to form a steel plate B ″. As a result, the iron loss of the steel plate B ″ was W _17/50 = 0.98 W / kg.

However, for A ′ and B ″ steel plates, an additional 800
When the iron loss value after being subjected to _stress relief annealing at 3 ° C. for 3 hours was examined, the iron loss of the steel sheet A ′ did not change as W _17/50 = 0.95 W / kg, whereas that of the steel sheet B ″ did not change. Iron loss is W _17/50 = 1.05
It was significantly deteriorated to W / kg and reached the level before laser irradiation.

As a result of investigating the cause of this, in the steel plate B ″, before the strain relief annealing, a plastic strain region was formed in the surface layer portion of the ground iron immediately below the forsterite removed portion, and due to the existence of this plastic strain region, the magnetic domain was fragmented. It was achieved,
It was found that this plastic strain was released by strain relief annealing and disappeared. Therefore, in order to prevent deterioration of the characteristics by the strain relief annealing, it is essential to prevent the introduction of plastic strain into the surface layer of the steel sheet base metal.

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

The material of the present invention is obtained by a known steelmaking method, for example, a steelmaking method using a converter, an electric furnace, etc., and further a slab (steel piece) by an ingot-segmentation method or a continuous casting method, followed by hot rolling. A hot rolled coil is used.

This hot-rolled sheet needs to have a composition containing about 2.0 to 4.0% of Si. This is because if the Si content is less than 2.0%, the iron loss deteriorates significantly, and if it exceeds 4.0%, the cold workability deteriorates. As for the other components, any of the component components of the grain-oriented silicon steel sheet can be applied.

Next, although the final target thickness is obtained by cold rolling, the cold rolling is performed once or twice by sandwiching the intermediate annealing. At this time, the hot-rolled sheet may be subjected to uniform annealing or warm rolling instead of cold rolling, if necessary.

Next, the cold rolled sheet having the final thickness is subjected to primary recrystallization annealing in an oxidizing atmosphere capable of decarburizing or a weak oxidizing atmosphere capable of forming subscale.

Then, an annealing separating agent containing MgO as a main component is applied to the surface of the steel sheet.
By locally adhering various non-metallic substances or other metals or semi-metals other than alkali metals and alkaline earth metals, foreign substances can be arranged in the steel sheet surface layer portion or the forsterite coating.

That is, a forsterite film is formed by applying such a foreign substance and then applying an annealing separator, followed by secondary recrystallization annealing, followed by high temperature purification annealing and subsequent final annealing. Foreign matter diffuses into the ground iron or reacts with it to form foreign matter on the surface layer of the steel sheet. Unless such diffusion or reaction occurs, the foreign matter is mainly present only in the forsterite coating. It will be. Here, the substance to be arranged in the coating has the same effect even if any of the above-mentioned non-metals, metals, and semi-metals is used alone or in combination. Metals are excluded because they have poor stability.

At this time, in the surface layer portion of the ground iron on which the powder is arranged as described above, the cross section of the steel plate with the center of the arrangement point is a foreign matter having a shape as shown in Fig. 1 (a) (b) and (c) above. Is recognized. Depending on the type and amount of the placed material, this part is (i) an iron alloy phase that has the same composition as the base iron but has a very high solid solution amount of other elements, and (ii) different from the base iron It is either a metal, a semi-metal or an alloy phase, or (iii) a non-metallic substance, and is clearly distinguished from the composition of the ground iron.
Among them, the iron loss reduction effect of (i) and (ii) is somewhat superior to that of (iii).

Further, according to the present invention, as described above, a grain-forged grain-oriented silicon steel sheet with a foreign substance locally arranged on the surface layer of the base metal has a thermal expansion coefficient of 9.8 × 10 ^-6 1 / ° C. or less after the coating is formed. To produce a grain-oriented silicon steel sheet with an extremely low iron loss value, which is a synergistic effect of arranging foreign matter on the surface layer of the base metal and the effect of applying tension by the coating film by forming a tension-giving insulating coating film. You can

As for the type of coating, since the surface tension is given by the difference in the thermal expansion coefficient between the steel plate and the coating film, there must be some difference in the coefficient, but this point is 9.8 × 10 ^-6 1 / As long as it has a coefficient of thermal expansion of ℃ or less, a satisfactory low iron loss value can be obtained by the synergistic effect of the effect of forming a foreign substance existing area on the surface layer of the base metal and the surface tension imparting effect of the coating film. It is confirmed.

By the way, as the arrangement form of foreign matter in the surface layer of the ground iron,
A continuous linear shape is particularly effective, but other non-continuous or row of points can be replaced. However, in the case of such a discontinuous linear shape, the effect becomes small if the distance between the points is 0.5 mm or more. In addition, such a linear foreign matter arrangement width of about 0.05 to 2.0 mm is particularly effective.

Furthermore, the orientation of the linear foreign matter placement is 60 to 90 with respect to the rolling direction.
An angle range of ° is especially preferred. There is no effect in the direction parallel to the rolling direction, and the maximum effect is obtained in the direction perpendicular to the rolling direction. The angle with respect to the rolling direction of the steel sheet is particularly important, and the iron loss reduction effect is weakened when the width of the foreign substance existing region is too wide or when it is an isolated point because the directionality becomes unclear. .

Such continuous or discontinuous linear regions are preferably repeatedly present, including those having different shapes, widths, and angles with respect to the rolling direction, and the interval between the regions at this time is 1.0.
A range of ~ 30 mm is especially effective.

In addition, the effect of foreign matter on the surface layer of the base metal was almost the same whether it existed on both sides of the steel plate or only on one side.

As described above, the grain-oriented silicon steel sheet in which foreign matter having a composition different from that of the ground-iron is locally formed on the surface layer portion of the ground-iron is used as a product as it is like a normal grain-oriented silicon steel sheet. In each case, and when it is used as a product by further applying a tension-applying top coat insulating coating, it shows good characteristics when used in an actual device.

Here, according to the present invention, the iron core surface layer portion, the iron loss characteristics by arranging foreign matter having a composition different from that of the ground iron, the reason is improved, by arranging the foreign matter on the base iron surface layer portion, the steel plate surface It is thought that this is because elastic strain is introduced into the steel sheet by this different tension, and as a result, the magnetic domain width is effectively subdivided.

Furthermore, regarding the disposition form of the foreign matter, (i) a solid solution of a specific element in the base iron, (ii) a metal, a semimetal and an alloy phase different from the base iron, Unlike the case, the metal part is continuous with the steel plate surface layer part, and since it is a magnetic material, it has a small magnetic resistance and allows magnetic flux to pass, but the effect of further subdividing the magnetic domain due to discontinuity of magnetic permeability is added. Therefore, it is considered that the iron loss reducing effect was great.

Summarizing the above description, the basic requirement that the foreign matter region in the present invention should satisfy is that the foreign matter is arranged so that elastic strain is introduced by tension force or the area where the magnetic permeability is discontinuous. As the arrangement form, a phase in which a specific element is solid-dissolved in the base iron, a metal, a semimetal and an alloy phase different from the base iron, and a foreign substance composed of a non-metal substance such as an oxide are included. This is achieved by adopting the arrangement form as shown in FIG. 1 in the product sheet after the final finish annealing.

In the case of grain-oriented silicon steel sheets with such different tensile elastic strain, unlike the conventional method in which a plastic strain area or a high dislocation density area such as a laser irradiation mark exists in the surface layer of the base metal of the steel sheet, artificial Since the introduction of a typical plastic strain region is not observed, there is a remarkable advantage that there is almost no deterioration of iron loss even if strain relief annealing is usually performed at about 800 ° C. for 1 minute to several hours. In the former case, the plastic strain of the base metal surface layer has a fatal defect that deterioration of iron loss occurs because it disappears at high temperature, but in the case of the present invention, it is good regardless of the presence or absence of strain relief annealing. Indicates iron loss.

Further, in the steel sheet of the present invention, since the shape change portion is small, the space factor hardly decreases.

(Example) Example 1 C: 0.033%, Si: 3.25%, Mn: 0.07%, Se: 0.02%,
A silicon steel slab containing S: 0.01% and Sb: 0.015%, the balance being substantially Fe composition, was hot-rolled and then subjected to a double cold-rolling method with one intermediate annealing in between. A cold rolled sheet having a final sheet thickness of 0.22 mm was used. Then, the foreign substances were locally deposited by various methods shown in Table 1, partially before decarburization annealing and partially after decarburization annealing.

After that, after applying an annealing separator containing MgO as a main component, final finishing annealing was performed at 1200 ° C. for 3 hours to obtain a product.

In addition, a part was made a comparative example without adhering foreign substances.

The adhesion form of the foreign substance was changed in accordance with the adhesion method, but in each case, the angle was 90 ° with the rolling method, and the repeating interval was 4 mm.

In all of the product plates except the comparative example, the foreign substance region shown in FIG. 1 was formed in the surface layer of the base metal. Table 1 shows the results of examining the iron loss values of these products.

Next, on the surfaces of the comparative example and the conforming example C, I to I shown in Table 2
Each of the coating treatment liquids of VII was applied and then baked to form a top insulating coating.

Table 3 shows the magnetic properties of these products after strain relief annealing at 800 ° C. for 3 hours.

(Effects of the Invention) Thus, according to the present invention, it is possible to obtain a grain-oriented silicon steel sheet with low iron loss, the characteristics of which are not deteriorated even when subjected to strain relief annealing, which is advantageous.

[Brief description of drawings]

1 (a) (b) and (c) are cross-sectional views of the steel plate containing foreign matter having a composition different from that of the ground iron in the surface layer of the ground iron, and FIG. 2 (a) (b) and (c) are FIG. 3 is a diagram showing the shape of the foreign substance existing region partitioned and formed in the surface layer of the steel sheet, the inclination of the rolling direction and the measuring procedure of the interval, respectively. FIG. 3 shows that the angle formed by the linear foreign substance existing region with the rolling direction is
A graph showing the influence on the iron loss characteristics, Fig. 4 is a graph showing the relationship between the width of the region and the iron loss value, and Fig. 5 is a graph showing the relationship between the interval of the region and the iron loss value. FIG. 6 is a graph showing the relationship between the width of the foreign substance existing region and the iron loss value when the tension imparting coating film is applied and when it is not applied.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yo Ito 1 Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel Co., Ltd.

Claims (2)

[Claims] 1. A hot-rolled sheet obtained by hot-rolling a silicon-containing slab is cold-rolled once or twice with intermediate annealing to obtain a final sheet thickness, and then decarburized. In the method for producing a grain-oriented silicon steel sheet, which comprises a series of steps of performing primary recrystallization annealing, then applying an annealing separator containing MgO as a main component on the surface of the steel sheet, and then performing final finishing annealing, the annealing separator is used. Prior to the application of, by locally adhering various non-metallic substances or other metals or semimetals other than alkali metals and alkaline earth metals to the surface of the steel sheet, the surface layer of the steel sheet of the steel sheet, Is a method of manufacturing a grain-oriented silicon steel sheet having low iron loss, the characteristics of which are not deteriorated by strain relief annealing, in which foreign matters having different compositions are arranged. 2. A hot-rolled sheet obtained by hot-rolling a silicon-containing steel slab is cold-rolled once or twice with intermediate annealing to obtain a final sheet thickness, and then decarburized. In the method for producing a grain-oriented silicon steel sheet, which comprises a series of steps of performing primary recrystallization annealing, then applying an annealing separator containing MgO as a main component on the surface of the steel sheet, and then performing final finishing annealing, the annealing separator is used. Prior to the application of, by locally adhering various non-metallic substances or other metals or semimetals other than alkali metals and alkaline earth metals to the surface of the steel sheet, the surface layer of the steel sheet of the steel sheet, Place foreign matter of different composition on the forsterite film,
Characteristic is not deteriorated by strain relief annealing, which is characterized in that a tension imparting type insulating coating treatment liquid exhibiting a thermal expansion coefficient of × 10 ^-6 1 / ° C or less is applied and then baked in a temperature range of 600 to 900 ° C. Manufacturing method of low iron loss grain-oriented silicon steel sheet.