JP3127262B2 - {110} <001> Ultrathin electromagnetic steel strip with high degree of orientation integration and low iron loss - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention has an easy axis <001> orientation in the rolling direction, and a {110} plane appears on a rolling surface (a Miller index of {1}).
10 <001>) and a method for producing the same. The ultra-thin electromagnetic steel strip obtained by the present invention has a feature of high magnetic flux density and low iron loss despite being a thin material, and is used for a transformer for a medium or high frequency power supply or a control element.

(Prior art) The basic magnetic concept of grain-oriented electrical steel sheets was discovered in 1926 by the magnetic anisotropy of a single crystal of iron (K. Honda and S. Ka).
ya Sci.Reps.Tohoku Imp.Univ.15, (1926), p721) Thereafter, NP, Goss (U.S. Pat.
No. 5,559), the magnetic properties of grain-oriented electrical steel sheets have been greatly improved since the invention of a method for producing a material having a {110} <001> orientation texture.

The integration in the {110} <001> orientation in the electrical steel sheet is achieved by utilizing a catastrophic grain growth phenomenon called secondary recrystallization. In order to control the secondary recrystallization, it is essential to adjust the primary recrystallization structure before the secondary recrystallization and to adjust a fine precipitate or an element of a grain boundary segregation type called an inhibitor. This inhibitor has the function of suppressing the growth of grains other than the {110} <001> orientation in the primary recrystallized structure and selectively growing only the {110} <001> oriented grains.

Currently, there are three types of technologies for manufacturing typical grain-oriented electrical steel sheets that are industrially produced.

The first technology was developed by MFLittmann in Japanese Patent Publication No. 303651
This is a production technique based on a two-fold cold rolling process in which MnS functions as an inhibitor, which is disclosed in Japanese Unexamined Patent Publication (Kokai) Publication.

The second technology was developed by Taguchi and Sakakura in Japanese Patent Publication No. 40-15644.
This is a production technique started in Japanese Patent Application Laid-Open Publication No. HEI 7-175, in which AlN + MnS is made to function as an inhibitor, and a rolling reduction in final cold rolling is reduced to a high pressure exceeding 80%.

The third technique is a production technique by a two-fold cold rolling process in which MnS (or MnSe) + Sb functions as an inhibitor, which is disclosed in Japanese Patent Publication No. 51-13469 by Imanaka et al.

With these technologies, the magnetic flux density (B ₈ value) is now 1.
It is around 92 Tesla. A grain-oriented electrical steel sheet with a very high degree of {110} <001> orientation integration has been manufactured and is commercially available. However, in these manufacturing technologies using inhibitors, when the thickness of the material is reduced, the change behavior of the inhibitor through the interface becomes remarkable, so that it is difficult to industrially produce a thinner material, Currently, plate thickness
Those with 0.20mm or more are mainly produced.

By the way, the iron loss of grain-oriented electrical steel sheets in the high frequency range is
For example, RHPry, CPBean (J.Appl.Phys.29 (1958),
As reported in p. 532), the thickness increases in proportion to the square of the thickness, so that in order to obtain an electromagnetic steel sheet with low iron loss, it is essential to reduce the thickness.

In 1949, MFLittmann disclosed a method for producing thin silicon steel sheets in US Pat. No. 2,473,156. This technique uses a starting material with {110} <001> orientation texture,
Uses a process of cold rolling and recrystallization, and uses no inhibitors. The characteristics of the product obtained by this technology are as follows: a plate thickness of 1 to 5 mils (25.4 to 127 μm), a magnetic flux density (B ₈ value) of 1.600 to 1.815 Tesla, and an iron loss (frequency: 60
Hz, maximum magnetic flux density 1.0T) is 0.26-0.53W / 1b (0.44--0.
90W / kg). At present, ultra-thin electromagnetic steel strip is manufactured by this method. The characteristics are shown in FIG. 6 as a conventional product and compared with those of the product of the present invention.

With the recent development of electronic devices, it has been desired to reduce the size and efficiency of transformers, control elements, and the like for medium and high frequency power supplies. However, as described above, the ultra-thin electromagnetic steel strip obtained by the conventional technique has a low magnetic flux density and cannot be designed to have a high design magnetic flux density, so that the size of the device cannot be reduced. There was a problem that the iron loss at the time was extremely large.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned problems in the prior art, and provides an ultra-thin electromagnetic steel strip having extremely high magnetic flux density and low iron loss in a high excitation region, and a method for manufacturing the same. It is intended to be.

(Means for Solving the Problems) In order to reduce iron loss (especially iron loss in a high excitation region), the present inventors have made Si ≦ 8% by weight and the balance is made of Fe practically. An ultra-thin electromagnetic steel strip having an average particle size of ≦ 1.0 mm and a plate thickness of ≦ 150 μm, and has a magnetic flux density B ₈ / B _s > 0.9 (B _s : saturation magnetic flux density in the component system), and It has been found that a material (product) having an active domain wall is an essential requirement, and it is an object of the present invention to provide such an ultra-thin electromagnetic steel strip and a method for producing the same, and the gist thereof is as follows.

(1) Si ≦ 8% by weight, one or two of Sn and Sb
Containing 0.005 to 0.30% of seed, the balance being substantially composed of Fe, having a plate thickness of ≦ 150 μm, an average particle size of ≦ 1.0 mm, and {110} <001
> Area with orientation texture, magnetic flux density B ₈ / B _s > 0.9 (B _s : saturated magnetic flux density in its component system), and a region where the magnetic permeability is lower than that of ground iron (steel plate) An ultra-thin electromagnetic steel strip with a high degree of {110} <001> orientation accumulation and low iron loss characterized by having it periodically in the vicinity.

(2) Si ≦ 8% by weight, one or two of Sn and Sb
Species containing from 0.005 to 0.30%, balance being substantially Fe, {110} have the <001> orientation texture, the magnetic flux density B ₈ / B
_The unidirectional electrical steel strip with _s > 0.9 (B _s : saturated magnetic flux density in its component system) is subjected to at least one cold rolling applying a rolling reduction of 60 to 90% to a final thickness of 150 μm or less. {110} <001> orientation accumulation, characterized by periodically forming a region with a lower magnetic permeability than that of ground iron (steel plate) near the surface of the steel plate after the thickness and then primary recrystallization annealing Manufacturing method of ultra-thin electromagnetic steel strip with high degree and low iron loss.

(3) By weight, Si ≦ 8%, one or two of Sn and Sb
Species containing from 0.005 to 0.30%, balance being substantially Fe, {110} have the <001> orientation texture, the magnetic flux density B ₈ / B
_The unidirectional electrical steel strip with _s > 0.9 (B _s : saturated magnetic flux density in its component system) is subjected to at least one cold rolling applying a rolling reduction of 60 to 90% to a final thickness of 150 μm or less. {110} <001> orientation accumulation, characterized by periodically forming areas with low magnetic permeability in the vicinity of the steel sheet surface after the thickness, and then performing primary recrystallization annealing Manufacturing method of ultra-thin electromagnetic steel strip with high degree and low iron loss.

 Hereinafter, the present invention will be described in detail.

The silicon steel sheet is different from high-permeability materials such as permalloy and sendust in that the magnetic flux density at saturation is high, but the crystal magnetic anisotropy constant and the magnetostriction constant are both large. Therefore,
The feature is that high-frequency magnetization is hardly generated. Therefore, in order for the silicon steel sheet to be a static soft magnetic material, ideally, magnetization by only smooth 180 ° domain wall movement is ideal. For dynamic softness, it is important to subdivide the 180 ° domain wall spacing and increase the active domain wall.

Assuming magnetization by 180 ° domain wall motion, iron loss P can be conceptually expressed as follows.

Here, P _classical = K · Bm ² fd ² / ρc ² Bm: maximum magnetic flux density f: frequency d: plate thickness ρ: specific resistance c: light velocity L: domain wall interval P _i : uniformity of domain wall motion A term indicating the degree, and if all domain wall motion amplitudes are the same, P _i = 0.

M: In mobility of magnetic domain ^{walls, M = K · ρc 2 /} Bs 2 d W: width of sample Δv _i: short time pinning the magnetic domain wall movement speed change P _[001] by _tilt: surface by magnetization change in the thickness direction P _nucleation : A term related to loss due to the occurrence and annihilation of a lancet domain in magnetization. When magnetizing only by 180 ° domain wall movement, P _{[001] tilt} and P _nucleation become zero.

By the way, in the actual development of silicon steel sheets, P
The decrease of _classical is increase of Si content, decrease of thickness, decrease of L is 180 ° subdivision of domain wall spacing, decrease of P _i , P _{[001] tilt} and P _nucleation is {110} <001> orientation accumulation high orientation degrees, a decrease in Delta] v _i is distortion, impurity removal, corresponds to the interface smoothing.

The present invention relates to a high silicon ultra-thin steel sheet having a high degree of {110} <001> orientation integration and having finely divided magnetic domains.

FIG. 1 shows the relationship between frequency and iron loss in the ultra-thin electromagnetic steel strip of the present invention (marked with ○: magnetic flux density B ₈ value of the material = 1.94T) and the ultra-thin 15 μm-thick material whose magnetic flux density is low. The values are shown in comparison with electromagnetic steel strips (□: magnetic flux density of the material B ₈ value = 1.55T). From FIG. 1, it can be seen that an ultra-thin electromagnetic steel strip having a high magnetic flux density and periodically having a low magnetic permeability region exhibits a low iron loss value in a high frequency region. Such ultra-thin magnetic steel strips with high magnetic flux density, together with low iron loss, can increase the design magnetic flux density, making it possible to reduce the size of equipment, as well as transformers for medium and high frequency power supplies and control. Dramatically improve device characteristics.

Next, a method for manufacturing such an ultra-thin electromagnetic steel strip will be described in detail.

The present inventors believe that, as described above, when the thickness of the electromagnetic steel strip is reduced, inhibitor control becomes difficult and secondary recrystallization becomes unstable, and the primary recrystallization without using an inhibitor causes A study was conducted to increase the degree of integration in the 110｝ <001> direction. As a result, a unidirectional electromagnetic steel strip having an extremely high degree of {110} <001> orientation accumulation was used as a starting material, and this material was subjected to cold rolling to a final thickness of 150 μm or less, and then from the grain boundaries. It has been found that an ultra-thin electromagnetic steel strip having a sharp degree of {110} <001> orientation and having a low iron loss value can be produced by performing primary recrystallization annealing while suppressing recrystallization of.

Such findings were obtained by the following experiments.

By weight, Si: 3.3%, C: 0.002%, N: 0.002%, Al: 0.002
%, S: 0.0002%, Mn: 0.13%, balance is substantially Fe and unidirectional electromagnetic steel strip having {110} <001> orientation texture (magnetic flux density (B ₈ value): 1.92T, average Particle size: 40mm, thickness: 0.
30 mm) was cold-rolled to a final thickness of 0.09 mm (90 μm), and then annealed at 850 ° C. for 10 minutes to complete the primary recrystallization.

The texture of the product thus obtained is shown in FIG. From FIG. 2, the orientation of primary recrystallized grains is
The {111} <011> orientation is mixed with the 0｝ <001> orientation, and it can be seen that the increase in grains in the latter orientation causes a decrease in magnetic flux density.

This texture is issued by MFLittmann in U.S. Pat.
It is clearly different from the texture ({210} <001> to {310} <001>) obtained by the method disclosed in the specification of 2,473,156. This is the starting material in the art of MFLittmann the magnetic flux density B ₁₀ = 1.74T as low as {110} <0
01> It is considered that this is because the degree of integration of the orientation is poor. Therefore, in order to achieve a high magnetic flux density of the product, it is necessary to increase the degree of integration of the {110} <001> orientation of the starting material,
It is necessary to suppress the primary recrystallization of 1｝ <011> oriented grains.

The present inventors have conducted a study on cold rolling and recrystallization of the starting material, and found that {110} <001> oriented grains are from inside the starting material grains and {111} <011> oriented grains are mainly from grain boundaries. Nuclear outbreak,
Clarified to grow. Based on this understanding, in order to increase the degree of integration of ultra-thin products to the {110} <001> orientation, it is necessary to reduce the grain boundary area of the starting material or suppress nucleation from the grain boundaries It has been found.

 Hereinafter, specific steps will be described.

The present inventors have found that in order to increase the magnetic flux density of a product, it is important that the starting material has a high degree of {110} <001> orientation integration and that nucleation from grain boundaries is reduced. Starting from a unidirectional magnetic steel strip of various grain sizes having a magnetic flux density B ₈ /Bs>0.9, based on
After performing cold rolling to apply a rolling reduction of 150 μm or less to a final thickness of less than 150 μm, annealing in a temperature range of 700 to 900 ° C. and primary recrystallization, and magnetic measurement of the obtained ultrathin electromagnetic steel strip is performed. Was. As a result, in order to obtain an ultra-thin electromagnetic steel strip having a magnetic flux density of 1.85 Tesla or more, the starting unidirectional magnetic steel strip
By adding one or two of Sb and Sb, nucleation of {111} <011> oriented grains from grain boundaries is suppressed,
It has been found that the degree of integration in the 0 ° <001> direction can be increased and the magnetic flux density of the product can be improved.

 Such findings were obtained by the following experiment.

By weight, Si: 3.2%, C: 0.002%, N: 0.001%, Al: 0.002
%, S: 0.0004%, Mn: 0.05% as basic components, Sn and S
Cold-rolled unidirectional electromagnetic steel strip (magnetic flux density (B ₈ value) = 1.90 T, average grain size: 5 to 40 mm, sheet thickness 0.14 mm) containing 0 to 0.5% of one or two types of b This gave a final thickness of 30 μm.
This material was annealed at 850 ° C. for 10 minutes to complete the primary recrystallization.

FIG. 3 shows the relationship between the Sn content and the magnetic flux density of the obtained product. From FIG. 3, it can be seen that the nucleation of {111} <011> oriented grains from the crystal grain boundaries can be suppressed and the magnetic flux density of the product can be improved from the Sn addition amount: 0.01%. 0.30% Sn addition
The magnetic flux density decreases when the magnetic flux density exceeds 1, because the grains of the unidirectional electromagnetic steel strip, which is the starting material, become finer, the grain boundary area increases, and the frequency of nucleation from the grain boundaries increases. It is considered to be.

When the starting material contains one or two of Sn and Sb in a total amount of 0.03 to 0.30%, as shown in FIG.
The ultimate level of the magnetic flux density (B ₈ value) of the obtained product is 1.94 Te
It will be extremely high with sla. Furthermore, since the cold rolling reduction at which the product has the highest magnetic flux density shifts to the higher cold rolling reduction side as compared with those not containing one or two types of Sn and Sb, the starting material having the same thickness is used. Extremely thin products can be obtained. Also, since the preferred cold rolling reduction region in which the product has a high magnetic flux density is greatly expanded as compared with those not containing one or two of Sn and Sb,
From a starting material having a certain gauge, it becomes possible to produce ultra-thin electromagnetic steel strips of various gauges having a high magnetic flux density.

As described above, the addition of one or two of Sn and Sb to the starting material, which characterizes the present invention, nucleates from grain boundaries which cause a reduction in the magnetic flux density of the product {111} <011>.
It functions effectively to suppress nucleation and growth of oriented grains and preferentially generate and grow {110} <001> oriented grains.

The magnetic flux density of the ultra-thin electromagnetic steel strip of the present invention obtained in this way is much better than the magnetic flux density of the ultra-thin electromagnetic steel strip obtained by the conventional technique.

Next, the effect of reducing iron loss by periodically forming the low magnetic permeability region near the steel sheet surface will be described.

Free magnetic poles are generated in the low magnetic permeability region near the surface of the steel sheet, in the ground iron with high magnetic permeability, and in the boundary region between them, due to the discontinuity of spontaneous magnetization. This free region increases the magnetostatic energy of that region. In order to alleviate the magnetostatic energy, auxiliary domains having a magnetization component in the thickness direction are generated in these regions. The interaction between the tension generated in the steel sheet by the surface film and the magnetostriction of the ground iron eliminates these auxiliary magnetic domains. The increase in the magnetostatic energy due to the elimination of the auxiliary magnetic domain is mitigated by the subdivision of the 180 ° domain wall interval (the increase in the active domain wall). Therefore, the number of active domain walls depends on the density of free magnetic poles in the boundary region.

The state of the iron loss reduction effect due to the tension described above is described in the fifth section.
Shown in the figure.

In FIG. 5, {110} <0 where the surface film was removed
01> Iron loss value of ultra-thin magnetic steel sheet with a high degree of orientation integration and a thickness of 50 μm, the iron loss value when a 0.9 kg / m ² tension is applied to the sample in the rolling direction; The values indicate iron loss values measured when grooves having a depth of about 3 μm were formed in a direction perpendicular to the direction at intervals of 1.25 mm, and a tension of 0.9 kg / mm ² was applied in the rolling direction. The reduction of the iron loss value from to is caused by the interaction between the auxiliary magnetic domain and the tension which the iron has. The decrease in the iron loss value from the core is caused by the interaction between the auxiliary magnetic domain generated in the low magnetic permeability region, that is, the gap and the tension. In the state of C, it can be seen that the iron loss value is extremely low. It can be seen that the formation of such a low magnetic permeability region is extremely effective for realizing low iron loss.

The low magnetic permeability region mentioned here corresponds to, for example, 1) unevenness of the steel sheet surface 2) a non-ferromagnetic substance such as an oxide, and in any case, a free magnetic pole can be formed.

The shape of the magnetization curve, iron loss, magnetic permeability and the like strongly depend on the density of the free magnetic pole.

If the interval between the low magnetic permeability regions is too large, or if the magnetic permeability region is too wide, the density of the free magnetic pole naturally becomes low, and the influence on the magnetization characteristics of the material becomes small. on the other hand,
If the depth of this region in the plate thickness direction is too large, the density of the free magnetic pole is increased, but the magnetic properties of the material are significantly deteriorated. When this region is shallow, deterioration of the magnetization characteristics of the material is reduced. Therefore, when aiming to reduce the iron loss of the ultra-thin electromagnetic steel sheet, it is important to suppress the depth of the low magnetic permeability region to an appropriate value and increase the number of active domain walls. That is, the required function (for example, the shape of the magnetization curve, the iron loss, the magnetic permeability, etc.) of the device in which this material (product) is used, and the width of the low magnetic permeability region suitable for the thickness of the material, etc. It is necessary to select the interval and depth.

Example 1 Si: 3.2%, Mn: 0.05%, C: 0.002%, N: 0.001 by weight
%, Al: 0.002%, S: 0.001%, Sb: 0.02%, with the balance being substantially Fe, a grain-oriented electrical steel sheet (B ₈ = 1.90T, grain size: R _D =
(6 mm, R _C = 6 mm, thickness: 140 μm) was pickled to remove the glass film, and then cold-rolled to a final thickness of 26 μm.
Then, after annealing at 1000 ° C. for 5 minutes in an atmosphere of H ₂ : 100%, an insulating film forming treatment was performed in an N ₂ atmosphere. The product thus obtained is irradiated with a laser, and a laser spot interval in a direction perpendicular to the rolling direction: 0.2 mm, a laser spot row interval:
Scanned at 1.0 mm. The insulating film was removed only from the laser-irradiated portion, and this steel sheet was immersed in concentrated nitric acid for about 10 seconds, then washed with water and dried. By such processing, the diameter: about 110μ
m, depth at the center: Holes of about 3 μm were periodically formed. FIG. 7 shows the iron loss characteristics of the ultra-thin electromagnetic steel sheet thus obtained before and after the laser treatment.

Example 2 Si: 3.0%, Mn: 0.06%, C: 0.003%, N: 0.002% by weight
%, Al: 0.001%, S: 0.001%, Sn: 0.07%, balance: Unidirectional electromagnetic steel strip consisting essentially of Fe (B ₈ = 1.88T, particle size: R _D =
(5 mm, R _C = 3 mm, thickness: 230 μm) was pickled to remove the glass film and then cold-rolled to a final thickness of 50 μm. After the steel plate (strip) was degreased, an acid-resistant paint was applied. Next, holes were formed in this steel sheet by the same treatment as in Example 1, and the acid-resistant paint was removed. After that,
Annealed at 850 ° C for 10 minutes in an atmosphere of N ₂ : 25% + H ₂ : 75%
Further, an insulating film forming treatment was performed in an N ₂ atmosphere. FIG. 6 shows the iron loss characteristics of the product thus obtained.

(Effect of the Invention) The product obtained by the present invention has the following excellent magnetic properties.

(1) The magnetic flux density at an exciting force of 800 A / M is, for example, 3
In the case of% Si, the magnetic flux density is 1.84 to 1.95 T, which is about 0.2 to 0.4 T higher than the magnetic flux density of the product obtained by the conventional technology.

(2) The iron loss value of the product, for example, _W15 / _400, is about 50% of the iron loss value of the product obtained by the prior art, and shows an extremely low value. In particular, the iron loss value at high excitation of 1.5 T or more has no precedent.

If such a product of the present invention is used for a transformer, especially a transformer for a high-frequency power supply, a remarkable effect is brought about in terms of miniaturization and efficiency. The product of the present invention has a great effect when applied to a control element.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between frequency and iron loss, FIG. 2 is a pole figure showing the texture of a product obtained as a result of an experiment on which the knowledge of the present invention was obtained, and FIG. , shows the added flux density ₍₈ value B) of the ultra-thin electrical steel strip and Sn content of relationship Sn, Fig. 4 flux of the cold rolling rate and product in Sn additive and additive-free material of the present invention FIG. 5 is a diagram showing the relationship between densities, FIG. 5 is a diagram showing the principle of the present invention, and FIGS. 6 and 7 are diagrams showing iron loss of the product of the present invention.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tadao Nozawa 1-1-1 Edamitsu, Yahata-Higashi-ku, Kitakyushu-shi, Fukuoka Prefecture Nippon Steel Corporation 3rd Technical Research Institute (72) Inventor Masaru Iwasaki Yawata, Kitakyushu-shi, Fukuoka E1-1, Higashi-ku, Nippon Steel Corporation 3rd Technical Research Institute −198430 (JP, A)

Claims (3)

(57) [Claims] 1. The composition according to claim 1, wherein Si ≤ 8%, one or two of Sn and Sb are contained in an amount of 0.005 to 0.30%, and the balance is substantially made of Fe, with a plate thickness ≤ 150 μm and an average particle size ≤ 1.0 mm. And {110} <0
01> has orientation texture, magnetic flux density B ₈ / B _s > 0.9 (B _s : saturated magnetic flux density in its component system), and ground iron (steel plate)
An ultra-thin electromagnetic steel strip having a high degree of {110} <001> orientation accumulation and low iron loss, characterized by periodically having a region having a low magnetic permeability near the surface of the steel sheet as compared with that of the above. 2. The composition according to claim 1, wherein said alloy contains, by weight, Si ≦ 8%, one or two of Sn and Sb in an amount of 0.005 to 0.30%, the balance substantially consisting of Fe, and a {110} <001> orientation texture. And the magnetic flux density B ₈
Apply at least one cold rolling to a unidirectional magnetic steel strip with / B _s > 0.9 (B _s : saturated magnetic flux density in its component system) at a rolling reduction of 60 to 90% and 150 μm or less {110} <001> characterized by periodically forming a region having a lower magnetic permeability than that of ground steel (steel plate) near the surface of the steel plate after subjecting it to the final plate thickness and then subjecting it to primary recrystallization annealing. A method for producing an ultra-thin electromagnetic steel strip having a high degree of orientation accumulation and a low iron loss. 3. The composition according to claim 1, wherein Si ≦ 8% by weight, one or two of Sn and Sb are contained in an amount of 0.005 to 0.30%, and the balance is substantially composed of Fe and has {110} <001> orientation texture. And the magnetic flux density B ₈
Apply at least one cold rolling to a unidirectional magnetic steel strip with / B _s > 0.9 (B _s : saturated magnetic flux density in its component system) at a rolling reduction of 60 to 90% and 150 μm or less {110} <001> characterized by periodically forming a region having a lower magnetic permeability than that of the base steel (steel plate) near the surface of the steel plate after the final thickness, and then subjecting it to primary recrystallization annealing A method for producing an ultra-thin electromagnetic steel strip having a high degree of orientation accumulation and a low iron loss.