JPH0680612B2 - Low iron loss grain-oriented silicon steel sheet whose properties do not deteriorate due to stress relief annealing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) Regarding a grain-oriented silicon steel sheet having a low iron loss, the technical contents described in this specification, especially non-uniformity in the surface layer portion of the base steel including the coating on the surface of the steel sheet This is related to improving iron loss by partitioning and forming a region where different tension acts on the surface or a region where magnetic permeability is discontinuous when applied.

The grain-oriented silicon steel sheet is mainly used as an iron core for transformers and other electric devices, 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. A low iron loss of 1.05 W / 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 as a core material for them, grain-oriented silicon steel sheets with even lower iron loss are required. 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 some improvement is recognized, the effect of iron loss improvement is small in spite of the efforts.

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 the magnetic domain is miniaturized and the core loss is reduced by irradiating the steel sheet with a high dislocation density region on the surface of the steel sheet.

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 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.

Furthermore, in this purification annealing, SiO ₂ in the subscale of the steel plate surface layer and MgO in the annealing separator applied to the surface react as in the following formula, 2MgO + SiO ₂ → Mg ₂ SiO ₄ , 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. The steel sheet that has undergone high-temperature purification annealing is then processed into a product by removing the unreacted annealing separating agent and, if necessary, performing the treatment of removing the overcoat of the insulating coating and the coil set.

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 further detailed examination of the subdivision tendency 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 magnetic domain more effective. He found that subdivision was achieved.

The present invention is derived from the above findings.

That is, the present invention is a grain-oriented silicon steel sheet with a forsterite coating in which a plastic strain region is not seen in the surface layer portion of the base steel, and in the surface layer portion of the base steel of the steel sheet, (i) Any one selected from the following: an iron alloy phase having the same phase but having a very high solid solution amount of another element, (ii) a metal different from base iron, a metalloid or an alloy phase, and (iii) an oxide. It is a low iron loss grain-oriented silicon steel sheet that does not deteriorate in properties even by strain relief annealing, which is formed by arranging one or two kinds of foreign matter having a composition different from that of the base steel.

Further, the present invention is a grain-oriented silicon steel sheet with a forsterite coating in which no plastic strain region is found in the surface layer of the base metal,
A foreign material having a composition different from that of the above-described base iron is locally arranged on the surface layer of the base steel of the steel sheet, and a thermal expansion coefficient of 9.8 × 10 ⁻⁶ 1 / ° C. or less is applied to the forsterite coating. It is a low iron loss grain-oriented silicon steel sheet which does not deteriorate in properties even by strain relief annealing, which is provided with a tension imparting type insulating coating film.

Here, a foreign substance having a composition different from that of the base iron will be described in more detail. The foreign substance has a composition in which (i) the same phase as the base iron but a solid solution amount of another element is extremely high. Iron alloy phase (eg V, Nb, Cr, Mo, Mn, C
(diffusion phase of substitutional solid solution elements such as o, Ni, Cu, Zn, Si and As), (ii) a phase different from that of base iron, electrostatic coating, plating,
Metals, semi-metals and alloy phases different from the base metal formed by deposition methods such as printing (eg Ni, Cr, Sb, Al, Sn, G
e, Si, Ni-W, Cr-Mo, Fe-W, Sn-Ni, Sn-Co and Ni-Co), (iii) oxides (such as Fe, Si, Al, Ti, Zr and Sb) Oxide) phase, and so on.

In addition, the arrangement of foreign matter on the surface layer of the steel plate of the steel sheet is as shown in Fig. 1
As indicated by b, c, and d, it does not refer only to the case where a foreign substance is completely embedded in the ground iron, but exists only when it extends over both the ground iron and the forsterite coating and only in the forsterite coating. It includes the case of doing.

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, in a laboratory, 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 the 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 annealing at 1200 ° C. for 5 hours (both are collectively referred to as final finish annealing) were performed.

As a result, in the place where Ni powder was embedded in the surface layer of the steel plate, the steel plate cross-section centered around the point where Ni was embedded has a shape as shown in Fig. 1 (a) (b) (c). It was found that the magnetic domain width of the steel sheet was subdivided at this location.

It is difficult to artificially control the existence form of foreign substances as shown in FIGS. 1 (a), 1 (b) and 1 (c) by the method of embedding a foreign substance during rolling as described above. However, all the effects were the same as the subdivision effect of the magnetic domain width. That is, if the foreign matter phase of different composition shown in FIGS. 1 (a), 1 (b) and 1 (c) is formed in the final product, the magnetic domain can be subdivided by any other method. It is something.

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

As a result, it was confirmed 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 in the surface layer of the ground iron. . However, in the discontinuous linear form, the effect decreased when the distance between the dots 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, as shown in Fig. 2 (b) and Fig. 3, it is particularly effective when the angle is 60 to 90 ° with respect to the rolling direction. 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 interval between regions as shown in FIG. As shown in FIG. 5, it is desirable that the range is 1 mm to 30 mm.

Moreover, the effect of the foreign matter was almost the same whether the foreign matter was placed on both sides of the steel plate 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 to form a tension-imparting insulating coating film, the iron loss was measured, and as shown in FIG. 6, as compared with the case where the foreign matter 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, for a forsterite-coated grain-oriented silicon steel sheet containing 3.0% Si and having a plate thickness of 0.28 mm, a steel sheet A according to the present invention in which foreign matter is locally arranged on the surface layer of the ground iron, and a homogeneous base steel A conventional steel plate B having a surface layer and a uniform and homogeneous forsterite coating was prepared.

At this time, the iron loss of each steel plate is W _17/50 = 1 for steel plate A.
For 01 W / kg and B, W _17/50 = 1.05 W / kg.

Then, after forming a coating on the surface of each of these steel sheets A and B, 5.6
When a steel sheet A ', B'was formed by applying a tension-imparting top coat coating having a coefficient of thermal expansion of × 10 ^-6 1 / ° C,
The iron loss of each steel plate is W _17/50 = 0.96W / k for steel plate A '.
For g and B ', W _17/50 = 1.04 W / kg, confirming the composite action of the tension-imparting coating film of the present invention.

Further, with respect to the steel plate B ′, the coating and the forsterite are exhibited together by utilizing the irradiation of the pulsed high power laser beam, which is a conventionally known iron loss improving method, so that the row of dots (dots of dots) can be obtained. A region of 0.4 mm) was formed to form a steel plate B ″. As a result, the iron loss of the steel plate B ″ was 0.98 W / kg.

However, for A ′, B ″ steel plates, an additional 800
When the iron loss value after being subjected to strain 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 = 0.96 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 preferably has a composition containing Si of about 2.0 to 4.0%. 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.

Now, as one of the methods of locally disposing foreign matter having a composition different from that of the base steel locally on the steel sheet surface layer part, during the cold rolling described above, various oxides or alkali metals and alkaline earth metals are removed. Other metal or metalloid powder locally,
There is a method of embedding these substances on the surface of the steel sheet by adhering to the surface of the steel sheet and then continuing and completing rolling.

As the material to be embedded, the same effect can be obtained by using any of the above-mentioned oxides or metals and metalloid powders alone or in combination, but among the metal powders, alkali metal or alkaline earth Regarding metals, even if the amount is a little, they are transferred to other regions other than local areas during cold rolling and spread, which hinders the formation of forsterite film during secondary recrystallization annealing performed after cold rolling and decarburizing annealing. I decided to exclude it.

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 separator containing MgO as a main component is applied to the surface of the steel sheet, followed by secondary recrystallization annealing and then purification annealing at high temperature to obtain a forsterite-coated grain-oriented silicon steel sheet.

While such high-temperature purification annealing removes unnecessary elements from the steel, some inhibitor elements may not be sufficiently removed from the steel even by such high-temperature purification annealing. However, even if such an element remains, the amount thereof is small, so that it can be treated as an impurity.

By the way, prior to the application of the above-mentioned annealing separator, a metal such as a metal having a different composition from the above-mentioned base iron, a different substance such as a semimetal and an oxide, is applied to the surface of the annealed plate by a method such as electrostatic coating, plating or printing. Foreign matter can also be placed in the surface layer of the steel sheet or in the forsterite coating by attaching the foreign matter.

That is, a forsterite coating is formed by applying the above-mentioned foreign substance, applying the annealing separator, then performing the secondary recrystallization annealing, followed by the high-temperature purification annealing and the subsequent final finishing annealing. However, during such final finishing annealing, foreign substances diffuse into the ground iron, and react with the ground iron to form foreign substances on the surface layer of the steel sheet. It will only be present in the stellite coating.

At this time, in the surface layer portion of the ground iron on which the dissimilar substances are arranged as described above, the steel plate cross-section with the arrangement point as the center is as shown in Fig. 1 (a), (b) and (c) above. Presence of foreign matter is recognized.

Depending on the type and amount of the placed material, this point is (i) an iron alloy phase that has the same phase as that of the base iron but has a very high solid solution amount of other elements, and (ii) the base iron Are different metals, semi-metals or alloy phases, and (iii) oxides, which are clearly distinguished from the composition of base iron.
The phase different from that of the base iron and the region of the high solid solution amount of the placed substance are detected in the steel plate surface layer portion where the foreign matter is placed and processed, and the cross-sectional portion of each element is EPMA (electron probe micro By scanning with an analyzer)
It is possible.

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, the grain-forged grain oriented silicon steel sheet with foreign matter locally arranged on the surface layer of the base metal further 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 synergistic between the effect of disposing foreign matter on the surface layer of the base iron and the effect of applying tension by the coating film, by forming a tension-giving type insulating coating film. You can

As 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 If the material has a coefficient of thermal expansion of / ° C or less, a satisfactory low iron loss value can be obtained due to the synergistic effect of the effect of forming a foreign substance existing area on the surface layer of the base metal and the effect of applying surface tension by the coating film. It is confirmed that it will be done.

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.

The effect of the foreign matter on the surface layer of the base metal was almost the same whether it existed on both sides of the steel sheet or on only 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.

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

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

In a grain-oriented silicon steel sheet to which such different tension elastic strain is added, unlike the case of the conventional method in which a high dislocation density region such as a plastic strain region or a laser irradiation mark exists in the surface layer of the base steel of the steel plate, 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 part has a fatal defect that the iron loss deteriorates 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: 0.04%, Si: 3.3%, Mn: 0.065%, Se: 0.02%, S: 0.01% and Sb: 0.014% are contained, and the balance becomes composition of Fe substantially. When the silicon steel material is made into a cold-rolled steel sheet having a thickness of 0.28 mm according to a conventional method, the steel sheet is
After splitting, one side as it is, 0.28 mm thick cold-rolled sheet is finished decarburizing and primary recrystallization annealing, and then an annealing separator containing MgO as a main component is applied, followed by secondary recrystallization annealing and 1200 ° C. ,
A final finish annealing consisting of 5 hours of annealing was given as a comparative example.

On the other hand, for other steel sheets, a rare earth metal powder containing Ce50%, La25%, etc., such as Nd on the surface of the steel sheet is attached width: 1 mm, angle formed with the rolling direction: 90 °, repeat interval in the rolling direction: 2 mm Then, the final cold rolling was continued to finish the cold rolled sheet with a thickness of 0.28 mm. Then, similarly to the above, this steel sheet was also subjected to decarburization / primary recrystallization annealing, then an annealing separator having MgO as a main component was applied thereto, and then final finish annealing was performed to obtain a product. As a result, in the former, the surface layer of steel plate base metal had a homogeneous composition, but in the latter, the area where the rare earth metal was embedded was investigated by EPMA, and as a result, 75 to 95% of the rare earth metal was contained in the surface layer of the base metal. The second phase composed of a rare earth alloy with a high content of (Fe: 5 to 25%) was formed.

The iron loss values of these products were as follows.

Comparative Example W _17/50 = 1.05 W / kg Example W _17/50 = 1.00 W / kg Next, the coating treatment liquids I to VII shown in Table 1 are applied and baked onto such steel sheets. As a result, a top coat insulating film was formed.

The iron loss value of the obtained product was as shown in Table 2.

Then, the iron loss value after further performing stress relief annealing at 800 ° C. for 2 hours was examined, and the results are also shown in Table 2.

From Table 2, it can be seen that in the case where foreign matter is arranged on the surface layer of the base steel, the core loss is significantly improved due to the presence of the coating film having a thermal expansion number of less than 9.8 × 10 ^-6 1 / ° C. .

Example 2 Silicon steel material containing C: 0.032%, Si: 3.0%, Mn: 0.07%, Se: 0.024%, S: 0.01% and Sb: 0.012%, the balance being substantially Fe composition When making a cold-rolled steel sheet having a thickness of 0.30 mm in accordance with the ordinary method, during the final cold rolling, the steel sheet was
Divide into 3 parts into D and E, and for steel plate C, 0.3
A cold rolled sheet with a thickness of 0 mm is finished, followed by decarburization and primary recrystallization annealing, and then an annealing separator containing MgO as a main component is applied, followed by secondary recrystallization annealing and 1200 ° C. purification annealing for 3 hours. Final finishing annealing consisting of and was performed as a comparative example.

On the other hand, for steel plate D, Al ₂ O ₃ powder was applied to the steel plate surface, and for steel plate E, Ni powder was applied to the steel plate surface, respectively, adhesion width: 1 mm, angle formed with rolling direction: 90 ° C., repeating interval in rolling direction After adhering under the condition of: 3 mm, final cold rolling was continued to finish a cold rolled sheet with a thickness of 0.30 mm. Then, for these steel sheets D and E, decarburization and
After the primary recrystallization annealing, an annealing separator containing MgO as a main component was applied, and then a final finish annealing was performed.

As a result, when each steel plate was investigated by EPMA, the steel plate C had a homogeneous composition on the surface layer of the steel plate, but the steel plate D,
Regarding E, at the position of the base metal surface layer in which the Al ₂ O ₃ powder and the Ni powder were embedded, respectively, in the steel plate D, the oxide phase consisting of Al ₂ O ₃ and in the steel plate E, the phase of 3% silicon steel was used. However, the regions each containing solid solution Ni as high as 3 to 7% were obtained. In addition, the width of the region of Al ₂ O ₃ in the steel plate D is
At 1.5 mm, the repeating distance in the rolling direction was 4.5 mm, and in the steel sheet E, the width of the high Ni content region was 1.1 mm, and the repeating distance in the rolling direction was also 4.5 mm.

The iron loss values of these steel sheets C, D and E were as follows.

_Steel plate C (Comparative example) W _17/50 = 1.08 W / kg Steel plate D (Example) W _17/50 = 1.04 W / kg Steel plate E (Example) W _17/50 = 1.02 W / kg Steel plates C ', D'obtained by applying a tensioning type coating shown in IV of Table 1 on steel plates C, D and E
When the iron loss of E and E ′ was investigated, they were as follows.

Steel C'W _17/50 = 1.07W / kg steel D'W _17/50 = 1.00W / kg steel E'W _17/50 = 0.98W / kg Further, 800 ° C. These samples, straightening of 5 hours The iron loss value when annealed was examined, but there was no change.

Example 3 Silicon steel material containing C: 0.033%, Si: 3.25%, Mn: 0.07%, Se: 0.02%, S: 0.01% and Sb: 0.014%, the balance being substantially Fe composition When making a cold-rolled steel sheet having a thickness of 0.30 mm in accordance with the conventional method, the steel sheet was subjected to F, G, H, and H during the final cold rolling.
I and J are divided into 5 parts, F is finished as it is to a cold rolled steel sheet with a thickness of 0.30 mm, then decarburization and primary recrystallization annealing are applied, and then an annealing separator containing MgO as a main component is applied. Then, a final finishing annealing consisting of secondary recrystallization annealing and 1200 ° C. for 3 hours of refining annealing was performed to make a comparative example.

On the other hand, steel plate G is divided into three parts G1, G2, G3, and Ni-P is used for G1.
, Cu-Ni for G2 and Ni-Co for G3, respectively.
It was linearly plated under the conditions of 0.3 mm, the angle formed with the rolling direction: 90 °, and the repeating interval in the rolling direction: 3 mm. Similarly, the steel plate H was similarly divided into two parts H1 and H2, and Ni was plated on H1 and Cr was plated on H2 linearly under the same deposition conditions as in the above G.
Further steel I is divided into five parts, Si ₃ N _4, the Cr-Mo, I2 to I1 I3
For BN, SiC for I4, TiC for I5, area width: 1 mm,
After being attached under the conditions of an angle of 90 ° in the rolling direction and a repeating interval in the rolling direction: 3 mm, the final cold rolling was continued to finish a cold rolled sheet with a thickness of 0.30 mm. Then these steel plates
Similarly to steel plate F, G1, G2, G3, H1, H2, and I1 to I5 were subjected to decarburization / treatment after primary recrystallization annealing.

For steel sheet J, a cold-rolled steel sheet with a thickness of 0.30 mm is finished as it is, then divided into 6 parts, Ni for J1 and Ni for J2.
-P, Cu-Ni for J3, Ni-Co for J4, Fe-O (iron oxide) for J5, Si-O (silicate) for J6, the same formation as G above Plating linearly under the conditions, followed by decarburization-1
After performing the secondary recrystallization annealing, an annealing separator containing MgO as a main component was applied, and then a final finishing annealing consisting of secondary recrystallization annealing and 1200 ° C. for 3 hours of purification annealing was performed.

The results of examining the iron loss characteristics of the steel sheet thus obtained are shown in Table 3.

Further, in the steel sheet after such final finish annealing, the foreign matter forming portion was examined by EPMA, and as a result, it was found that G1 was a Fe ₃ Ni phase in which Ni is 26% and P is 0.1% in solid solution, and G2 is a Cu phase and Ni A phase of silicon steel that forms a solid solution of about 5% is formed, a phase of silicon steel that forms a solid solution of about 5% of Ni and about 2% of Co is formed on G3, and FeNi is formed on H1.
An alloy phase is formed of a silicon steel phase in which H2 contains 12% Cu as a solid solution, and a phase in which I2 contains about 8% Cr and about 5% Mo and I2 contains about Si. 7% solid solution phase of silicon steel is
Alloy phase FeB is, the phase of silicon steel a solid solution of about 10% of Si in the I4 is the I5 phases formed of TiFe ₂ respectively, or even an alloy phase of Fe ₃ Ni in J1 is, J2 Fe ₃ Ni alloy phase containing P, J ₃ containing Cu phase and 12% Ni containing silicon steel phase, J 4 containing about 6% Ni and 20% Co. A phase of silicon steel and an oxide phase of Mg ₂ SiO ₄ (forsterite) were formed in J5 and J6, respectively.

When the samples were further subjected to stress relief annealing at 800 ° C. for 5 hours, the iron loss was also examined, and the iron loss value did not change.

(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 a steel sheet containing foreign matter having a composition different from that of the base iron in the surface layer of the base iron, and FIGS. 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 (6)

[Claims] 1. A grain-oriented silicon steel sheet with a forsterite coating in which no plastic strain region is observed in the surface layer of the base steel, wherein (i) the base steel is locally added to the surface layer of the base steel of the steel plate. It is selected from among the iron alloy phase that has the same phase but has a very high solid solution amount of other elements, (ii) a metal different from base iron, a metalloid or an alloy phase, and (iii) an oxide phase. A low iron loss grain-oriented silicon steel sheet which does not deteriorate in properties due to stress relief annealing, characterized in that one or two kinds of foreign matter having a composition different from that of the base iron are arranged. 2. The arrangement of foreign matter having a composition different from that of base steel
The grain-oriented silicon steel sheet according to claim 1, which has a continuous or discontinuous linear form. 3. The grain-oriented silicon steel sheet according to claim 1 or 2, wherein the continuous or discontinuous linear form forms an angle of 60 ° to 90 ° with respect to the rolling direction of the steel sheet. 4. A forsterite-coated grain-oriented silicon steel sheet having no plastic strain zone in the surface layer of the base steel, which is locally (i) the same as the base steel in the surface layer of the base steel. Any one selected from the group consisting of an iron alloy phase that is a phase but has a very high solid solution amount of another element, (ii) a metal different from base iron, a metalloid or an alloy phase, and (iii) an oxide phase. One or two kinds of foreign matter having a composition different from that of the base metal should be arranged, and a tension-giving insulating coating film exhibiting a thermal expansion coefficient of 9.8 × 10 ^-6 1 / ° C or less should be provided on the forsterite film. A low-iron loss grain-oriented silicon steel sheet whose characteristics are not deteriorated by strain relief annealing. 5. The arrangement form of foreign matter having a composition different from that of the base metal,
Claim 4 which is a continuous or discontinuous linear form.
A grain-oriented silicon steel sheet as described in the item. 6. The grain-oriented silicon steel sheet according to claim 4, wherein the continuous or discontinuous linear form makes an angle of 60 ° to 90 ° with respect to the rolling direction of the steel sheet.