JPH02243720A - Production of thin grain-oriented silicon steel sheet having high magnetic flux density and excellent in iron loss - Google Patents

Abstract

PURPOSE:To stably obtain the grain-oriented silicon steel sheet by heating a silicon steel slab with the prescribed composition at high temp., applying annealing and quenching to the above between hot rolling and final cold rolling stages, subjecting the resulting sheet to final cold rolling, and then carrying out treatment, such as decarburizing annealing in a wet atmosphere. CONSTITUTION:A silicon steel slab having a composition represented by the right-hand description by weight percentage is heated at a high temp. in the vicinity of about 1,400 deg.C and subjected to hot rolling in which rolling of >=20% draft is performed six times or more in its finish rolling. Annealing is applied to the above once or more at 1,030-1,200 deg.C for <=10min between the above hot rolling and final cold rolling stages, followed by quenching by means, e.g., of immersion into 100 deg.C hot water. Subsequently, the above rolled steel sheet is subjected to final cold rolling at 81-95% draft, and, in the course of this final cold rolling, the sheet is held three times or more at 150-300 deg.C for >=30sec. Then, the resulting steel sheet of 0.05-0.25mm final sheet thickness is subjected to decarburizing annealing in a wet atmosphere and a separation agent at annealing composed principally of Mg is applied to this sheet, and further, high-temp. finish annealing is carried out, by which the desired thin grain-oriented silicon steel sheet having high magnetic flux density and excellent in iron loss can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a thin, high magnetic flux density unidirectional electrical steel sheet with low core loss.

[Prior Art] Unidirectional electrical steel sheets are used as soft magnetic materials mainly as magnetic core materials for transformers and other electrical equipment, and must have good magnetic properties such as excitation properties and core loss properties.

In order to obtain a steel sheet with excellent magnetic properties, the axis of easy magnetization is <
001> It is necessary that the axes are highly aligned in the rolling direction. In addition, plate thickness, crystal grain size, resistivity, surface coating, etc. greatly affect magnetic properties.

The directionality of electrical steel sheets has been greatly improved through the intense reduction single-stage cold rolling process in which A℃N and MnS function as inhibitors, and now steel sheets with magnetic flux densities of approximately 96% of the theoretical value are manufactured. It is coming.

On the other hand, in recent years, reflecting the soaring energy prices, transformer manufacturers have increasingly focused on low iron loss magnetic materials as materials for energy-saving transformers.

Amorphous alloys and 6.5%S are used as low iron loss magnetic materials.
Although the development of high-Sl materials such as i-alloys is progressing, they have drawbacks in terms of cost, workability, etc. as materials for transformers.

On the other hand, it is known that the iron loss of electrical steel sheets is greatly influenced by the sheet thickness in addition to the Si content, and when the thickness of the product is reduced by chemical polishing or the like, the iron loss decreases.

Conventional techniques related to the manufacturing method of thin high magnetic flux density unidirectional electromagnetic copper plates include JP-A-57-41326, JP-A-58-217630, and JP-A-60-59044.
No. 1, JP-A-61-79721, JP-A-61-
A technique disclosed in Japanese Patent No. 117215 and the like is known.

JP-A-57-41326 discloses that at least one of S and Se is used as an inhibitor in the range of 0.010 to 0.
．． 035%, at least one selected from Sb, As, Bi, and Sn from 0.010 to o,
A manufacturing method using a material containing oso% as a starting material is disclosed.

JP-A-58-217630 discloses C: 0.22.
~0.12%, Si:2.5~4.0%, Mn
: 0.03~0.15%, S: 0.01~0.0
5%, Al: 0.01-0.05%, N: 0.004
-0.012%, Sn: 0.03-0.3%, or the above-mentioned material further contains Cu: 0.02-0.02%.
A manufacturing method starting from a material containing 0.3% is disclosed.

JP-A-60-59044 discloses that C: 0.02~
0.10%, Si: 2.5-4.5%, Sn:
0.04-0.4%, acid acceptable? Tolerance Al: 0.0
15-0.040%, N: 0.0040-0.
0100%, Mn: 0.030-0.150%
, S: 0.015 to 0.040% as an essential component,
Others 0.04% or less Se, 0.4% or less Sb
, Cu , As , Bi or two selected from
A manufacturing method using a silicon steel material containing at least one species as a starting material is disclosed.

JP-A-61-79721 discloses Si: 3.1 to 4.
．． 5%, Mo: 0.003-0.1%, acid-soluble Ae +0.005-0.06%, total amount of any one or two of S and Se: 0.005-0.
A manufacturing method starting from a silicon steel material containing 1% is disclosed.

JP-A-61-117215 discloses C: 0.03.
~0.10%, Si:2.5~4.0%, Mn
: 0.02~0.2%, S: 0.01~0.04
%, acid soluble A#: 0.01.5-0.040%
, N: containing 0.0040 to 0.0100%, Se of 0.04% or less, Sn of 0.4% or less
, Sb, AsB1. A manufacturing method using a silicon steel material containing one or more selected from Cu and Cr as a starting material is disclosed.

[Problem to be solved by the invention]

In a unidirectional electrical steel sheet, the thinner the product thickness and the higher the magnetic flux density, the greater the iron loss reduction effect when magnetic domain refining is performed using a laser or the like.

On the other hand, unidirectional electrical steel sheets are manufactured by utilizing inhibitors such as A j2 N and MnS to induce secondary recrystallization during final annealing, but as the products become thinner,
There is a tendency that it becomes difficult to stably express ideal secondary recrystallization.

On the other hand, demands from transformer manufacturers for materials with lower core loss and lower prices are becoming stronger day by day, and products with lower core loss must be manufactured using more stable and lower cost methods. From this point of view, the above-mentioned prior art is no longer necessarily satisfactory.

The present invention has been made with the aim of overcoming the limitations of the prior art described above and providing a process that can stably produce products with even better characteristics.

[Means to solve the problem]

The characteristics of the present invention are as follows: In weight%, C: 0.050 to 0.120%, Si: 2
．． 8-4.5, Mn: 0.050-0.090%
Dekatsu Mn: {1.5×(S(%)+Se(%
))) ~(4,5X (S (%) + Se (%))}
%, S: 0.035% or less, Se: 0.00
5 to 0.035% and (S + Se): 0.
015-0.060%, N: 0.0050-0.0
100, acid-soluble Al: ((27/14)×N(%
) +0.0030}~{(27/14) ×N (%
)+0.0150}%, SnO, 05-0.25%,
Alternatively, in weight%, C: 0.050 to 0.120%,
Si: 2.8-4.5, Mn: 0.050-0.
090% and Mn: {1.5×(S(%)+
Se(%))) ~(4,5X (S(%)+Se(
%))}%, S: 0.035% or less, Se: 0.
005-0.035% Big (S + Se):
0.015-0.060%, N: 0.0050-0
．． 0100%, acid soluble Ajf! : ((27/1
4) ×N (%) +0.0030}~{(27/1
4) ×N (%) +0.0150}%, Sn 0.0
5 to 0.25%, Cu: 0.03 to 0.30%, Sb: 0.005 to 0.035%, or both, the balance: Fe and inevitable impurities. A silicon steel slab is heated at high temperature. Then, in the finish rolling of the hot rolling, rolling with a reduction ratio of 20% or more is performed for 6 passes or more, and at least 10 passes are carried out at least once between the hot rolling and the final cold rolling.
Annealed within 10 minutes at a temperature range of 30-1200'C,
After annealing, it is rapidly cooled, and in the final cold rolling, the rolling reduction is 81 to 95.
%, hold at 150 to 300°C for 30 seconds or more three times or more during the final cold rolling, and the final plate thickness is 0.05 to 0.2.
5 m/m, decarburization annealed in a humid atmosphere, coated with an annealing separator mainly composed of magnesia, and high-temperature finish annealing to produce a thin, high magnetic flux density unidirectional type VA steel sheet with excellent core loss. enables the production of

The present inventors first thoroughly investigated the effects of alloying additive elements on the production of thin grain-oriented electrical steel sheets that use iN as the main inhibitor and are characterized by final cold rolling under heavy reduction.

Experiment I C: 0.080%, Si: 3.20%, Mn:
0.020-0.120%, S: 0.025%,
Acid soluble AN: 0.0100-0.0450%, N
: 0.0020-0.0120%, remainder: substantially F
A large number of silicon steel slabs with a thickness of 200 m/m consisting of e, and C: 0.080%, Si: 3.20%, Mn: 0
．． 020-0.120%, S: 0.025%, acid-soluble Al: 0.0100-0.0450%, N:
0.0020 to 0.0120%, and Sn
: 0.13%, Se: 0.010%, Cu: 0
．． 07%, Sb: 0.020%, AS: o
, o! Contains one or more selected from 5o%, Bi: 0.10%, Cr: 0.10%, and the remainder:
A number of slabs of 200 m/m thick consisting essentially of Fe were heated at 1400° C. for 4 hours, extracted from the heating furnace and rough rolled into bars of 40 m/m thick. Thereafter, finish rolling was performed to a plate thickness of 1.4 m/m by 6 passes of uniform reduction rolling. The temperatures before and after finish rolling are 1230 to 1250, respectively.
℃ and 1030-1050℃. Further, the time required for finish rolling was within 20 seconds.

The hot-rolled sheet was heated to 1120°C, held for 80 seconds, and then rapidly cooled.

This material was cold rolled to 0.145 mm with 5 aging treatments at 250°C for 5 minutes in between.
The final plate thickness was set as .

Next, the 75% N2. N2.15%N2 atmosphere, 20℃
/hr heating rate to 1200°C, then H2
After soaking in an atmosphere at a temperature of 1200° C. for 20 hours, the product was cooled, the annealing separator was removed, and a tension coating was applied to obtain a product.

The iron loss value of this product was measured. The results are shown in FIG. As is clear from Fig. 1, relatively good iron loss values were obtained when the slab contained Sn, especially when it contained both Sn and Se. Good iron loss values were obtained.

AI! , N as the main inhibitors, and in the production of thin unidirectional electrical steel sheets characterized by final cold rolling under intense pressure, when the material contains Sn or Sn and Cu, high magnetic flux density steel sheets with excellent core loss are produced. It is already known in JP-A-51217630 that a grain-oriented electrical steel sheet can be obtained.

A new finding obtained through experiment (2) is that by adding Sn and Se in combination, an even closer iron loss value can be obtained.

Furthermore, according to experiment (2), no effect of improving the iron loss value by adding As, Bi, or Cr was observed.

As shown in FIG. 1, even in the case of combined addition of Sn and Se, it was found that the iron loss value still varied widely, and further improvement was required.

In order to reduce the variation in iron loss values of products with composite additives of Sn and Se, we decided to elucidate the effects of the contents of S, Se, Mn, N, and acid-soluble/M2.

Experiment ■ C: 0.075%, Si: 3.20%, Mn:
0.070%, S: no addition to 0.050%, Se
: Additive-free -0,050%, acid soluble AA: 0.024
0%, N: 0.0085%, Sn 0.13%, balance: A large number of silicon steel slabs with a thickness of 200 m/m consisting essentially of Fe were treated in the same manner as in Experiment I to obtain a product. The loss value and magnetic flux density were measured.

Figure 2 shows the relationship between iron loss value and slab components.

In FIG. 2, the horizontal axis is the S content, and the vertical axis is the Se content. Line ab in the figure.

Excellent (low) iron loss values were obtained in the regions surrounded by bc, cd, de, ef, and fa. Moreover, the magnetic flux density B8 value in this region was all 1.90T or more. straight line b
c and ef are each expressed by the following equations.

Straight line bc: s content (%) + Se content (%) - 0,0
60% Straight line ef: S content (%) + Se content (%) = 0
．． 015% From these, S: 0.035% or less, Se
;0.005-0.035% and total of S and Se: 0
．． It has become clear that a stable and excellent iron loss value can be obtained in the case of 0.015% to 0.060%.

Experiment ■ C: 0.075%, Si: 3.20%, Mn:
0.020 to 0.120%, S: no additive to 0.03
5%, Se: 0.005-0.035%, Total S and Se: 0.015-0.060%, Acid-soluble A12: 0.0240%, N: 0.0085%,
Sn: 0.13%, balance: 20 consisting essentially of Fe
A large number of silicon steel slabs with a thickness of 0 m/m were processed in the same manner as in Experiment I to obtain products, and the core loss value and magnetic flux density were measured.

The relationship between the iron loss value and the slab components at this time is shown in FIG. In Figure 3, the horizontal axis is the total amount of S and Se,
The vertical axis is Mn content.

Lines ab, bc, cd, de in FIG.

Excellent (low) core loss values were obtained in the region surrounded by ea. In addition, the magnetic flux density B8 in this region is 1.90 in both cases.
It was T or higher.

The straight lines bc and ea are each expressed by the following equations.

Straight line bc: Mn content (%) = 1.5X (total content of S and Se (%)) Straight line ea:
Mn content (%) -4,5X (Total content of S and Se (%)) From these, total amount of S and Se: 0.015 to 0.06
0%, Mn: 0.050 to 0.090%, and {1.5X (total content of S and Se (%))} to {4
, 5X (total content of S and Se N (%)))%,
It has become clear that stable and excellent (low) iron loss values can be obtained.

Experiment ■ C: 0.075%, Si: 3.20%, 'Mn
: 0.070%, S: 0.015%, Se
: 0.015%, acid soluble A7! :0.0100
~0.0450%, N: 0.0020~0.012
0%, Sn: 0.13%, remainder: Fe. %! A product was obtained by processing in the same manner as in (2), and the iron loss value and magnetic flux density were measured.

Figure 4 shows the relationship between iron loss value and slab components.

In FIG. 4, the horizontal axis is the N content, and the vertical axis is the acid-soluble Aρ content.

Excellent (low) iron loss values were obtained in the region surrounded by straight lines ab, bc, cd, and da in FIG. Further, the magnetic flux density B8 in this region was all 1.90T or more. Straight lines ab and cd are each expressed by the following equations.

Straight line ab: acid soluble A7! (%) = ((27/14) ×N (%) +0.0150
) (%) Linear cd: Acid-soluble Al (%) = ((27/14) ×N (%) +0.0030
) ”(%) From these things, N: 0.0050
~0.0100%, acid-soluble Al: ((27/1
4) ×N (%) +0.0030}~{(27/1
4) It has become clear that an excellent iron loss value can be obtained when ×N, (%) +0.0150)%.

Here, (27/14) ×N (%) means that all the N contained in the steel is AI! , corresponds to the 11 content required for N. In the nature of utilizing AjHJ as the main inhibitor, the secondary recrystallization phenomenon that affects the iron loss value of the product is influenced by the acid-soluble Al content based on (27/14) x N (%). It is understood that

Experiment V C: 0.075%, Si: 3.25%, Mn:
0.070%, S: 0.015%, Se:
0.015%, acid soluble A7! :0.0255%, N
: 0.0085%, Sn: 0.15%, remainder: The thickness of the bar after rough rolling, the number of passes of finish rolling, and each pass in hot rolling of a large number of 200 m / m thick slabs consisting essentially of Fe. By changing the rolling reduction rate at 1.4 m/m
It was made into a thick hot-rolled plate. The temperature before and after finish rolling is 1
The temperature was 230 to 1250°C and 1030 to 1050°C, and the time required for finish rolling was within 20 seconds. Regarding the hot rolling conditions and other conditions other than those mentioned above, a product was obtained by processing in the same manner as in Experiment ①, and the iron loss value of the product was measured.

FIGS. 5 and 6 show the relationship between the number of passes of finish rolling in hot rolling, the rolling reduction in each pass, and the iron loss value of the product.

FIG. 5 shows the case of constant reduction rolling. The horizontal axis is the number of rolling passes, and the vertical axis is the rolling reduction rate of each pass. The iron loss value is O2Δ,
Indicated by a symbol such as X. As is clear from FIG. 5, it was found that good iron loss values were obtained when the rolling reduction was 20% or more and the number of rolling passes was 6 or more.

FIG. 6 shows a case where the rolling reduction ratio is different in each pass.

The horizontal axis is the number of rolling passes with a rolling reduction of 20% or more, and the vertical axis is the iron loss.

As is clear from FIG. 6, it has been found that good iron loss can be obtained when the number of rolling passes at a reduction rate of 20% or more is 6 or more.

As the product plate thickness becomes thinner, the influence of the interfacial reaction on the entire plate thickness becomes relatively larger during high-temperature finish annealing. , it is necessary to precisely build up both sides of the inhibitor texture in the previous process. At the current stage, it is still difficult to quantitatively discuss the ideal state of inhibitors and collective tissues. As mentioned above, the reason why the iron loss value of thin high magnetic flux density unidirectional electrical steel sheets becomes good is probably when the number of rolling passes with a rolling reduction of 20% or more is 6 or more in the finish rolling of hot rolling. This is thought to be mainly due to advantages in terms of texture.

As mentioned above, from the results of Experiment ■, Experiment ■, and Experiment ■, it is clear that
In the manufacturing method of thin unidirectional electrical steel sheets using silicon steel slabs containing Si and Sn, in order to stably obtain an excellent core loss value of the product, a predetermined amount of C and Si must be added as components of the starting material. , In addition to Sn, the content relationship of S and Se, S
The relationship between the content of -5-3e- and the relationship between the content of N and acid-soluble Al are important.Furthermore, from the results of Experiment V, the rolling reduction rate and number of passes in finish rolling in hot rolling are important. The present inventors have found that this is important.

That is, as components of the starting material, in addition to predetermined amounts of C and 5iSn, S: 0.035% or less, Se: 0
．． 005-0.035%, total amount of S and Se: 0.
015-0.060%, Mn + 0.050-0
．． 090% and {1.5X (total content of S and Se (%
))} ~ {4,5X (total content of S and Se (%))}
%, N: 0.0050-0.0100%, Acid-soluble Aff: ((27/14) x N content (%) 10, 00301% - ((27/14) x N content (%)
) - 0.01501%, and by performing 6 or more passes of rolling with a rolling reduction of 20% or more in the finish rolling during hot rolling, a thin, high magnetic flux density unidirectional product with an excellent (low) iron loss value. The present invention was completed based on the knowledge that it is possible to stably manufacture electromagnetic '@ plates.

From the results of Experiment I, in addition to the composite additive of Sn and Se,
When either one or both of Cu and sb is added,
It became clear that the iron loss value of the product was further improved.

In order to obtain stable and excellent iron loss values for these materials,
Experiments similar to the above-mentioned Experiments (1), (2), (2), and (2) were conducted and similar results were obtained, and it was determined that the present invention can be effectively applied to these Cu- and Sb-added steels.

C: 0.075%, Si: 3.25%, Mn:
0.070%, S: 0.015%, Se
: 0.015%, acid soluble/10, 0255%, N
A large number of silicon steel slabs with a thickness of 200 m/m containing 40.0085%, Sn: 0.15%, Cu addition-free, and 0.01-0.50% were treated in the same manner as in the experiment ① above. , got the product.

The relationship between Cu content and iron loss value is shown in FIG.

As is clear from Figure 7, Cu: 0.03-0.30%
The iron loss value becomes low (good) in the range of .

C: 0.078%, Si: 3.20%, Mn:
0.076%, S: 0.018%, Se:
0.016%, acid soluble/10.0255%, N
: 0.0080%, Sn: 0.13%, Sb: 200m containing no additive and 0.001 to 0.050%
A number of silicon steel slabs of / m thickness were processed in a similar manner to Experiment I to obtain products.

The relationship between sb content and iron loss value is shown in FIG.

As is clear from Fig. 8, Sb: 0.005 to 0
．． The iron loss value becomes low (good) in the range of 0.035%.

Next, the reasons for limiting other components and manufacturing process conditions in the present invention will be described.

C is preferably 0.050 to 0.120%. 0.05
If it is less than 0% or more than 0.120%, secondary recrystallization in the final annealing step becomes unstable.

Si is preferably 2.8 to 4.5%. If it is less than 2.8%, a good (low) iron loss value cannot be obtained, and if it exceeds 4.5%, workability (ease of cold rolling) deteriorates.

Sn is preferably 0.05% to 0.25%. 0.05%
If it is less than 0.25%, secondary recrystallization will be poor, and if it exceeds 0.25%, workability will deteriorate.

1030 at least once between hot rolling and final cold rolling
It is desirable to perform annealing within a temperature range of ~1200°C for 10 minutes or less, followed by rapid cooling. If the temperature is less than 1030'C, good product magnetic properties cannot be obtained, and if it exceeds 1200'C,
Secondary recrystallization becomes defective. Further, even if the product is annealed for more than 10 minutes, the product characteristics will not improve. During annealing, 50-250 P
Decarburizing PM is effective in improving the magnetic properties of products.

The reduction ratio in the final cold rolling is preferably 81 to 95%. If it is less than 81%, good product magnetic properties cannot be obtained, and if it exceeds 95%, secondary recrystallization becomes poor.

In order to obtain good product magnetic properties, it is desirable to perform holding at 150 to 300° C. for 30 seconds or more three or more times during the final cold rolling. The final plate thickness is preferably 0.05 to 0.25 m/m. If it is less than 0.05 m/m, secondary recrystallization becomes unstable, and if it exceeds 0.25 m/m, a good iron loss value cannot be obtained.

〔Example〕

Example I C: 0.082%, Si: 3.25%, Sn: 0.
13%, S: 0.003-0.037%, Se
: 0.002-0.040%, Mn: 0.0
40-0.110%, N: 0.0040-0.01
08%, acid soluble Ajl! : 0.0180~0.0
350%, Cu: no addition and 0.02 to 0.50%,
A large number of slabs with a thickness of 200 m/rr+ containing Sb: no additive or 0.020 to 0.060%, etc., and the remainder consisting essentially of Fe were heated at 1400°C for 4 hours and extracted from the heating furnace. Then, rough rolling was performed to obtain a bar having a thickness of 40 m/m. Thereafter, it was rolled to a thickness of 1.5 m/m by 6 passes of constant reduction rolling. The hot-rolled sheet was heated to 1120°C, held for 100 seconds, and then cooled by immersing it in hot water at 100'C. Next, a final plate thickness of 0.170 mm was obtained by cold rolling with aging treatment at 250° C. for 5 minutes 5 times during the rolling process.

Next, it was heated to 850°C in an atmosphere of 75% H2, 25% NZ and a dew point of 66°C, kept at that temperature for 120 seconds, cooled, and coated with an annealing separator mainly composed of magnesia. %H2, 15%N2 atmosphere at 25℃
/hr heating rate to 1200°C, then H2
After soaking in an atmosphere at a temperature of 1200° C. for 20 hours, the product was cooled, the annealing separator was removed, and tension coating was performed to obtain a product.

did.

The iron loss value (W+515G) and magnetic flux goodness (Ba) of the product were measured. The results are shown in Table 1. As is clear from Table 1, S, Se and the total amount of S and Se, Mn, N
, shows excellent (low) core loss values only when the acid-soluble Al is in the range of the present invention.

Moreover, when the contents of Cu and Sb are within the range of the present invention, even better characteristics are exhibited.

Example 2 200m/200m of the four types of components A, B, C, and D shown in Table 2
A silicon steel slab with a thickness of m was heated at 1400 °C for 4 hours, extracted from the heating furnace, and rough rolled to a thickness of 40 m /
It was set as a bar of m. After that, 2.0
Finish rolling was performed to a plate thickness of m/m.

The time required for finish rolling was within 20 seconds.

The material was heated to 1120°C, held for 120 seconds, and then cooled by immersion in 100°C hot water. +, l I'4
A part of the sample was cold rolled to a thickness of 1.2 m/m, heated to 1000°C, held for 60 seconds, and cooled by immersing it in hot water at 100°C. These materials were subjected to cold rolling with 5 aging treatments at 250°C for 5 minutes in between.
145m/m {from 1.2m/m), 0.250m
/ m (from 2,0 m / m).

Next, it was heated to 850°C in an atmosphere of 75% H, 25% N2 and a dew point of 66°C, kept at that temperature for 120 seconds, cooled, and coated with an annealing separator mainly composed of magnesia. , 25°C/hr in 15% N2 atmosphere
The product was heated to 1200° C. at a heating rate of 1,200° C., then soaked for 20 hours at 1200° C. in an H2 atmosphere, cooled, the annealing separator was removed, and a tension coating was applied to obtain a product.

The iron loss value (W+5/So) and magnetic flux density (B8) of the product were measured. The results are shown in Table 3. As is clear from Table 3, excellent (low) core loss values are shown only when the starting materials are in the composition range of the invention.

Table 3 Example 3 C: 0.075%, Si: 3.25%, Mn:
0.075%, S: 0.015%, Se:
0.020%, acid soluble, 110.0250%, N:
0.0040% and 0.0085%, Sn: 0.
Two 200m sheets consisting of 14% and the remainder/substantially Fe.
/ m thick silicon steel slab was heated at 1400℃ for 4 hours,
It was extracted from the heating furnace and roughly rolled to a thickness of 40m/
It was set as a bar of m. After that, 1.8 with 6 passes of constant rolling
Finish rolling was performed to a plate thickness of m/m. The time required for finish rolling was within 20 seconds. Next, it was heated to 1100°C, held at that temperature for 80 seconds, and then cooled by immersing it in hot water at 100°C.

This material was cold rolled to a thickness of 0.38 mm and 0.77 mm, then annealed by heating to 1000° C. and holding at that temperature for 60 seconds, and then immersed in hot water at 100° C. to cool.

This material was cold rolled to a thickness of 0.05 mm (from 0.38 mm) and 0.10 mm (from 0.38 mm) with 5 aging treatments at 250 °C for 5 minutes in between.
The final plate thickness was 77 mm. String 1 thus obtained was charged with 75% N2.25% N2 and a dew point of 64
After performing decarburization annealing by heating to 840°C in a C atmosphere and holding at that temperature for 90 seconds, an annealing separator containing magnesia as a main component was applied.

This material was mixed in a 75%N2.25%N2 atmosphere for 25%
Heating to 1200°C at a temperature increase of °C/hr, then H
Finish annealing was performed by soaking at a temperature of 1200° C. for 20 hours in a 2 atmosphere.

Next, the annealing separator was removed and tension coating was applied to produce a product.

The iron loss value (W1375o) and magnetic flux density (B8) of the product were measured.

The results are shown in Table 4.

Furthermore, on the surface of the product, 5+
Iron loss value (W+
3/So) was measured.

The results are also shown in Table 4. As is clear from Table 4, those using the materials in the component area of the present invention as starting materials have excellent iron loss.

Example 4 200m/200m of the four types of components A, B, C, and D shown in Table 5
A large number of slabs with a thickness of m were made into hot-rolled plates with a thickness of 1.4 m/m by variously changing the bar thickness after rough rolling in hot rolling, the number of passes of finish rolling, and the reduction rate in each pass. . For hot rolling conditions and other conditions other than those listed above, please refer to the experimental
A product was obtained by processing in the same manner as above, and the iron loss value was measured.

Table 6 shows the number of passes of finish rolling, the reduction ratio in each pass, and the iron loss value of the product.

As is clear from Table 6, excellent iron loss values were obtained when the number of rolling passes with a rolling reduction of 20% or more was 6 or more in finish rolling during hot rolling.

Condolence Table [Effects of the Invention] Since the present invention is constructed as described above, it has the effect of stably manufacturing a unidirectional electrical steel sheet with excellent core loss, especially a thin grain oriented electrical steel sheet.

[Brief explanation of drawings]

The first is a diagram showing the relationship between alloying elements added to the starting material (horizontal axis) and product iron loss value (vertical axis) in a thin unidirectional electrical steel sheet containing An as the main inhibitor. FIG. 2 is a diagram showing the relationship between the S content (horizontal axis) and Se content (vertical axis) of the slab and the iron loss value (indicated by 0, x, etc.) of the product. Figure 3 shows the total content of S and Se in the slab (horizontal axis) and M
FIG. 2 is a diagram showing the relationship between the n content (vertical axis) and the iron loss value of the product (indicated by O, X, etc.). Figure 4 shows the N content of the slab (horizontal axis) and acid-soluble AI! ,
FIG. 2 is a diagram showing the relationship between N content (vertical axis) and iron loss value (indicated by 0, X, etc.) of the product. FIG. 5 is a diagram showing the relationship between the number of passes of uniform reduction rate finish rolling in hot rolling, the reduction rate in each pass, and the iron loss value (indicated by 0, X, etc.) of the product. Figure 6 shows a finishing rolling ratio of 20% in hot rolling.
FIG. 3 is a diagram showing the relationship between the number of passes described above and the core loss value of the product. FIG. 7 is a diagram showing the relationship between the Cu content of the slab (horizontal axis) and the amount of change in iron loss value of the product due to Cu addition (vertical axis). FIG. 8 is a diagram showing the relationship between the sb content of the slab (horizontal axis) and the amount of change in iron loss value of the product due to sb addition (vertical axis).

Claims (2)

[Claims] (1) In weight%, C: 0.050-0.120%, Si
: 2.8 to 4.5, Mn: 0.050 to 0.090%, and Mn: {1.5×(S (%) + Se (%))} to {
4.5×(S(%)+Se(%))}%, S: 0.03
5% or less, Se: 0.005 to 0.035%, and (S
+Se): 0.015-0.060%, N: 0.005
0-0.0100, acid-soluble Al: {(27/14)×
N(%)+0.0030}~{(27/14)×N(%
)+0.0150}%, Sn0.05-0.25%, balance: Fe and unavoidable impurities, a silicon steel slab is heated at high temperature, and then finished rolled for 6 passes at a reduction rate of 20% or more. The above-mentioned hot rolling is performed, and at least once between the hot rolling and the final cold rolling,
Annealing is performed within 10 minutes at a temperature range of 0°C, followed by rapid cooling, and then final cold rolling with a rolling reduction of 81 to 95.
%, hold at 150 to 300°C for 30 seconds or more three times or more during the final cold rolling, and the final plate thickness is 0.05 to 0.2.
5 m/m, then decarburization annealing in a humid atmosphere,
A method for producing a thin, high magnetic flux density unidirectional electrical steel sheet with excellent core loss, which comprises applying an annealing separator containing magnesia as a main component and performing high-temperature finish annealing. (2) In weight%, C: 0.050-0.120%, Si
: 2.8 to 4.5, Mn: 0.050 to 0.090%, and Mn: {1.5×(S (%) + Se (%))} to {
4.5×(S(%)+Se(%))}%, S: 0.03
5% or less, Se: 0.005 to 0.035%, and (S
+Se): 0.015-0.060%, N: 0.005
0-0.0100, acid-soluble Al: {(27/14)×
N(%)+0.0030}~{(27/14)×N(%
)+0.0150}%, Sn0.05-0.25%, C
u: 0.03-0.30% and Sb: 0.005-0
．． A silicon steel slab consisting of one or both of 0.35% and the remainder: Fe and unavoidable impurities is heated at a high temperature, and then, in the finish rolling, hot rolling is performed in which 6 passes or more of rolling with a rolling reduction of 20% or more are performed. , between the hot rolling and the final cold rolling, annealing is performed at least once in a temperature range of 1030 to 1200°C for 10 minutes or less, followed by rapid cooling, and then final cold rolling at a rolling reduction rate of 81 to 1200°C. 95%, holding at 150 to 300°C for 30 seconds or more three times or more during the final cold rolling, and the final plate thickness to 0.05 to 0.25 m/m,
Next, a thin, high magnetic flux density unidirectional electrical steel sheet with excellent iron loss is characterized by decarburizing annealing in a humid atmosphere, applying an annealing separator mainly composed of magnesia, and performing high temperature finish annealing. manufacturing method.