JP2670108B2 - Method for manufacturing high magnetic flux density grain-oriented silicon steel sheet - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a grain-oriented silicon steel sheet having a (110) [001] orientation as a main orientation.

(Prior art) A method of manufacturing a grain-oriented silicon steel sheet in which AlN is used as a main inhibitor and the final cold elongation is performed at a rolling reduction of 80% or more is disclosed in Japanese Patent Publication No. 40-15644. The technology is disclosed. The characteristic of this grain-oriented silicon steel sheet with AlN as the main inhibitor is that a high magnetic flux density can be obtained.On the other hand, since the secondary recrystallized grain size is large, overcurrent loss is high and low iron loss is obtained. And the secondary recrystallization is not stable, and the magnetic flux density has a large variation.
Among these drawbacks, a method of reducing overcurrent loss is disclosed in Japanese Patent Publication No. 57-2252, a method of irradiating a steel plate with a laser beam, or a thermal expansion coefficient disclosed in Japanese Patent Publication No. 61-39395. The problem is being solved by a technique for artificially subdividing magnetic domains, such as a method of forming different regions.

These methods reduce the overcurrent loss by subdividing the magnetic domains, and the iron loss reduction effect when irradiated with a laser, a plasma jet, or the like becomes greater as the product sheet having a higher magnetic flux density and a smaller hysteresis loss.

Therefore, a technique for stably manufacturing a product having a high magnetic flux density with a small hysteresis loss has become important.

By the way, secondary recrystallization fluctuates even if it is manufactured under the same conditions.It is difficult to control the secondary recrystallization because it is a stochastic phenomenon.In particular, in the case of a thin plate having a thickness of 0.23 mm or less, an inhibitor such as AlN is subjected to finish annealing. It decomposes in and its suppressing power tends to be unstable, and thus secondary recrystallization is further unstable.

Here, as a technique for stabilizing the secondary recrystallization, a method of adding Sn and / or Cu is disclosed in JP-B-57-9419 and JP-A-58-217630, and JP-A-61-1576.
Japanese Unexamined Patent Publication No. 32 discloses the method of adding Sb and Cu, respectively.

However, these methods add secondary inhibitors such as Sn, Cu and Sb to make the secondary recrystallized grains finer and stabilize the secondary recrystallization. Since the diameter was smaller, the magnetic flux density tended to be lower.

(Problems to be Solved by the Invention) An object of the present invention is to propose a method for producing a grain-oriented silicon steel sheet having a high magnetic flux density in a high yield by stabilizing secondary recrystallization.

Means for Solving the Problems The inventors of the present invention have proposed an ideal method for producing a grain-oriented silicon steel sheet using AlN and MnSe and / or MnS and Sb as inhibitors. After examining various manufacturing conditions to bring the orientation closer to the [001] orientation, after holding at a constant temperature for a fixed time in finish annealing, heating at a predetermined heating rate and then performing secondary recrystallization annealing, then purifying annealing It has been found that a high-flux-density grain-oriented silicon steel sheet can be stably obtained by applying the above method.

 The present invention is derived from the above findings.

That is, this invention is C: 0.02-0.12 wt%, Si: 2.5-4.0
wt%, Mn: 0.03 to 0.15 wt%, sol.Al: 0.01 to 0.05 wt%, Sb: 0.
A hot rolled silicon steel slab containing 0.01 to 0.20 wt% and N: 0.004 to 0.01 wt%, containing a total of 0.01 to 0.05 wt% of S and / or Se, with the balance being iron and unavoidable impurities After hot-rolled sheet annealing and quenching, cold rolling is performed once or twice with intermediate annealing at a final rolling reduction of 80%.
Performed above, after the decarburizing annealing, in the method for manufacturing a grain oriented silicon steel sheet comprising a series of steps of performing a final annealing consisting of secondary recrystallization annealing and purification annealing, prior to the finish annealing, 700 ~ 840 ° C secondary After holding for 20 hours or more and 200 hours or less in a temperature range where recrystallization does not occur, secondary recrystallization annealing is performed while heating to the temperature range of purification annealing at a heating rate of 5 to 50 ° C / h. Method for producing high magnetic flux density grain-oriented silicon steel sheet characterized by subjecting to post-purification annealing (first invention) and C: 0.02 to 0.12 wt%, Si: 2.5 to 4.0 wt%, Mn: 0.03 to 0.15
wt%, sol.Al:0.01-0.05wt%, Sb: 0.01-0.20wt% and N: 0.004-0.01wt%, and further S and / or Se
0.01 to 0.05 wt% in total and Cu: 0.02 to 0.20 wt%, Sn:
High magnetic flux density directivity comprising the same process as in the first invention, using a silicon steel slab containing at least one of 0.02 to 0.20 wt% and Mo: 0.005 to 0.05 wt%, the balance being iron and unavoidable impurities. A method for manufacturing a silicon steel sheet (second invention).

By the way, in the primary recrystallization structure of grain-oriented silicon steel sheet subjected to final cold rolling at a reduction ratio of 80% or more, nuclei of secondary recrystallized grains can form nuclei of (110) [001] oriented grains. Secondary recrystallization is unstable because it often exists alone without being formed, and its number is small.

Here, as a method for stabilizing the secondary recrystallization,
-26493 discloses that cold rolling is performed at a material temperature in the range of 50 to 300 ° C, and 54-29182 discloses that the temperature is maintained between 300 and 600 ° C between cold rolling baths. A technique that requires treatment during rolling is disclosed. Increasing the material temperature during cold rolling increases the (110) [001] oriented grains in the temporary recrystallization structure, increases the nuclei of secondary recrystallization, and makes secondary recrystallized grains finer. This is intended to stabilize the secondary recrystallization and improve the magnetic properties.

However, according to the present invention, since (110) [001] oriented grains isolated in the primary recrystallized structure are preferentially generated as secondary recrystallized nuclei and then secondary crystallized, (110) ) It is a novel method that can stably cause secondary recrystallization and increase the magnetic flux density despite the extremely small number of [001] oriented grains. Cold rolling at the high material temperature as described above Also increases the number of grains deviated from the (110) [001] orientation, and does not necessarily improve the magnetic flux density.

In the present invention, first, in order to generate nuclei of secondary recrystallized grains, it is necessary to maintain the temperature in the temperature range of 700 to 840 ° C. for 20 hours or more.
When the holding temperature exceeds 840 ℃, MnS or MnSe
And Sb have a reduced ability to suppress the growth of grains other than (110) [001] oriented grains, and when held at that temperature, (110) [001]
The preferential nucleation of oriented grains does not occur, and the improvement in magnetic properties of the product after finish annealing is slight.

Next, as a material component for which the heat treatment according to the present invention is effective, it is essential to contain Sb in an amount of 0.01 to 0.20 wt%. In the steel containing no Sb, the inhibitor AlN in the steel is decomposed or coarsened due to the influence of the atmosphere through the surface of the steel sheet, and as a result, the inhibitory force is lost and the desired result cannot be obtained. It is known that Sb is concentrated on the surface, and it is presumed that Sb concentrated on the surface has eliminated the effect of the atmosphere on AlN.

Here, as a conventional technique of finish annealing, Japanese Patent Laid-Open No.
In the final publication annealing process of silicon steel material containing MnSe and / or MnS as a main inhibitor,
Fully developed secondary recrystallization at a temperature of 00 ℃, and 1000 ℃
It is disclosed that the purification annealing is performed at the above temperature.

On the other hand, the present invention relates to the condition of finish annealing applied to a material of a grain oriented silicon steel sheet using AlN as a main inhibitor, and in a material using AlN as an inhibitor, the holding temperature range of the present invention is in a range of 700 to 840 ° C. Does not cause secondary recrystallization. This point will be described in more detail below.

Fig. 1 shows a decarburized annealed sheet of grain-oriented silicon steel containing AlN and M
A comparison of the macrostructures of decarburized annealed sheets of grain-oriented silicon steel with nSe and Sb as inhibitors is shown at 840 ° C for 50 hours. The figure (a) shows the case where AlN is the inhibitor, and the figure (b) shows the case where MnSe and Sb are the inhibitors, but in the case of the figure (b), the secondary recrystallization is completely completed. However, in the case of the same figure (a), secondary recrystallized grains are not recognized at all. As shown in the figure, when AlN is used as the main inhibitor, the decomposition temperature of AlN is high and the grain growth suppressing effect works even at high temperature.Therefore, secondary recrystallization does not start by annealing at 840 ° C. , AlN as the main inhibitor, an annealing temperature of 950 ℃ or higher is required.

That is, in the present invention, it is essential to maintain the temperature range of 700 to 840 ° C. where secondary recrystallization does not occur, and the technique described in JP-A-50-123517 for controlling the development of secondary recrystallized grains. Is different from.

Further, the inventors conducted an experiment to add Sb to the problem of stabilization of secondary recrystallization for grain-oriented silicon steel sheets using AlN as a main inhibitor, especially for products with a thin finished sheet thickness.

That is, the steel A consisting of the components shown in Table 1 and the balance iron,
B, C, and D were manufactured under the conditions shown in Table 2, and 20 product plates were used as magnetic measurement samples. The results of those magnetic measurements are shown in Table 3, a typical macrostructure photograph is shown in Fig. 2, and the (110) (222) (200) planes of the decarburized annealed sheet were sampled by the X-ray inverse method. Table 4 shows the results of the measurement of the specific intensity of each.

It can be seen from Table 3 that the composition of Steel C in which Sb is contained in MnSe with AlN as the main inhibitor stably obtained good magnetic properties.

In the composition of Steel D containing Sb in MnS, the secondary recrystallized grains became fine grains and the magnetic flux density slightly decreased, but the characteristic fluctuations decreased. Stable and good magnetic properties have not been obtained with the components A and B containing no Sb.

From Table 4, the X-ray inverse strength of the decarburized annealed sheet is Se.
It can be seen that in the composition of Steel C containing Sb, the (110) altitude (222) strength increases and the (200) strength decreases as compared to Steel A containing no Sb. As the primary recrystallization texture of decarburization annealing, (110) strength becomes the nucleus of secondary recrystallization grains (110) [00
1] represents the strength of oriented grains, (222) strength is (110) [00
1) Think to represent (111) [112] oriented grains that promote the growth of oriented grains, and (200) intensity represents (100) [011] oriented grains that inhibit the growth of (110) [001] grains. You can Therefore, adding Sb to MnSe increased (222) the intensity (200) and decreased the intensity.
[001] It can be interpreted that the growth property of the grains was extremely good, and the properties were improved and the properties were stabilized.

Further, in steel D in which Sb is added to S, (222) is increased as compared with steel B in which Sb is not added, although it is not as remarkable as in the case of adding Se. Sb improves the texture of decarburized annealed sheet (110) [001]
It was found that the effect of improving the growth property of the oriented grains and improving the characteristics stably was particularly remarkable when Sb was added to Se.

(Operation) Next, the reasons for limiting the constituent features of the present invention will be described.

C: 0.02 to 0.12 wt% When C is less than 0.02 wt%, secondary recrystallization becomes poor, while
If the content exceeds 0.12 wt%, the decarburizing property and the magnetic properties are reduced, so the content is set in the range of 0.02 to 0.12 wt%.

Si: 0.25 to 4.0 wt% If Si is less than 2.5 wt%, good burnout cannot be obtained.
If it exceeds wt%, the cold rolling property deteriorates significantly, so 2.5-
The range was 4.0 wt%.

Mn and S and / or Se are components for forming Mns and / or MnSe.

First, Mn needs to be at least 0.03 wt% in order to exert its action as an inhibitor. On the other hand, if it exceeds 0.15 wt%, the solid solution temperature of MnS and MnSe becomes high, and it does not form a solid solution at normal slab heating temperature, and the magnetism is Since it deteriorates, the range was set to 0.03 to 0.15 wt%.

If S and / or Se exceeds 0.05 wt%, purification by purification annealing becomes difficult, while if less than 0.01 wt%, the amount of the inhibitor is insufficient, so the total amount is 0.01 to 0.05 wt%. However, the magnetic flux density is further improved by limiting S to less than 0.01 wt%.

Al and N are necessary for forming AlN, and the Al content is set to the range of 0.01 to 0.05 wt%. That is, if the amount of Al is too small, the magnetic flux density becomes low, and if it is too large, the secondary recrystallization becomes unstable. Further, if N is less than 0.004 wt%, the amount of AlN is insufficient, and if it exceeds 0.012 wt%, blisters are generated in the product, so the range is 0.004 to 0.012 wt%.

If Sb is less than 0.01 wt%, there is no surface thickening effect, and Sb is 0.
If it exceeds 20 wt%, problems occur in decarburization and formation of surface coating, so 0.01 to 0.20 wt% is set.

Further, Cu can be added in order to further improve the magnetic flux density. If the content of Cu is less than 0.02 wt%, there is no effect, and if it exceeds 0.20 wt%, the pickling property and brittleness deteriorate, so the content is set to 0.02 to 0.20 wt%. Furthermore, it is advantageous to add Sn to improve burnout, and the content of Sn is 0.20wt%.
If the amount is less than 0.20% by weight, brittleness is deteriorated. Therefore, the amount is limited to 0.020 to 0.20% by weight.

Further, Mo may be contained in order to improve the surface properties. If it is less than 0.005 wt%, there is no effect, and if it exceeds 0.05 wt%, the decarburization property deteriorates, so the content is made 0.005 to 0.05 wt%.

Next, the silicon steel slab composed of the above-described steel components is heated and then hot-rolled. The hot-rolled sheet is annealed at 900 to 1200 ° C, then rapidly cooled, and then once an intermediate annealing or 2
Cold rolling is performed twice with a final reduction of 80% or more.

Here, the reason for limiting the final cold rolling reduction to 80% or more is that the primary recrystallization structure for exhibiting the strong suppressing power of AlN is 80% reduction.
This is because if it is less than%, it cannot be obtained.

After cold rolling, decarburization annealing is performed, an annealing separator is applied, and finish annealing is performed. Finish annealing is performed at a temperature of 700 to 840 ℃ for 20 hours to 200 hours at a constant temperature, then 550 ℃ / h.
The temperature is raised to the temperature range of the purification annealing, for example, 1200 ° C.

Here, the suitable holding temperature fluctuates depending on the texture of the inhibitor and decarburized annealed sheet, but below 700 ℃ (110)
Magnetic properties are not improved because the generation of secondary recrystallization nuclei of [001] oriented grains hardly occurs. When the temperature exceeds 840 ° C, the inhibitory power of MnS and / or MnSe is lost, and grains other than (110) [001] oriented grains also grow normally and secondary recrystallization becomes poor. Therefore, the holding temperature is limited to 700-840 ℃.

If the holding time is less than 20 hours, the generation time of the secondary recrystallization nuclei of the (110) [001] -oriented grains is short, and the magnetic properties are not improved. Over 200 hours, the suppression of MnS, MnSe, and AlN decreases and secondary recrystallization becomes poor. Therefore, the retention time is 20
Time limited to ~ 200 hours.

After maintaining a constant temperature, the heating rate is less than 5 ℃ / h and 50 ℃
If it exceeds / h, the magnetic flux density decreases, so it is limited to 5 to 50 ° C / h. Purification annealing is performed in hydrogen at, for example, 1200 ° C. for 5 hours to purify S, Se, and the like.

It should be noted that the finish annealing of the component containing Sb in AlN 700 ~
After maintaining at a constant temperature in the range of 840 ℃ for 20 to 200 hours, 5
The reason why the magnetic characteristics are improved by increasing the temperature at ~ 50 ° C / h is estimated as follows.

MnS in the production of grain-oriented silicon steel sheets with AlN as the main inhibitor and the final cold rolling at a rolling reduction of 80% or more
Alternatively, the role of co-inhibitors such as MnSe or Sb is still unclear. Therefore, when various studies were carried out, the temperature at which the inhibitory effect was lost during finish annealing of AlN, MnS or MnSe was 950 to 1000 ° C for AnN and 800 to 950 ° C for MnS or MnSe.
Therefore, it was confirmed that MnS or MnSe loses the restraining force in the first half of the finish annealing. That is, the secondary recrystallization temperature in the production of grain-oriented silicon steel sheet in which AlN is the main inhibitor and the final cold rolling is performed at a reduction rate of 80% or more is 95%.
The temperature is 0 to 1000 ° C, and the suppressing force of MnS or MnSe is lost in this temperature range, so MnSe or MnS is AlN at the time of secondary recrystallization.
It does not contribute to the reinforcement of the suppression power of. When held in a temperature range of 700 to 840 ° C for 20 to 200 hours, usually AlN decomposes through the steel sheet surface according to the nitrogen potential of the atmosphere, or
It becomes coarse and loses its restraining power. However, when Sb is contained in the steel, while suppressing the influence of the atmosphere by the Sb concentrated on the surface (110)
By preferentially nucleating grains in the [001] orientation and growing to a size at which AlN can become secondary recrystallized nuclei until reaching the temperature range where the inhibitory force is exerted, excellent orientation (110) [001 ]
The secondary recrystallization of the orientation is promoted. In other words, the fact that high magnetic flux density can be obtained by such finish annealing is
This is a peculiar phenomenon in the steel in which Sb is further contained in the component system using MnSe or MnS as the main inhibitor with MnSe or MnS as the main inhibitor.

(Example) Example 1 C: 0.062 wt%, Si: 3.10 wt%, Mn: 0.075 wt%, Se: 0.024%,
A silicon steel slab comprising sol. Al: 0.025 wt%, N: 0.0086 wt%, Sb: 0.029 wt%, the balance being Fe, was heated at 1420 ° C for 20 minutes and hot rolled to form a 2.3 mm thick hot rolled sheet. This hot-rolled sheet at 1050 ℃ 2
After heating for 1 minute, it was rapidly cooled by mist spraying, and then cold-rolled to a thickness of 0.30 mm. After cold rolling, decarburization annealing combined with recrystallization at 840 ° C. for 4 minutes was performed, and then MgO was applied and finish annealing was performed. The magnetic properties of the product plate thus obtained are shown in Table 5. The conditions of cold rolling and finish annealing are as follows.

Note (i) Cold rolling condition A: Rolled at room temperature B: Rolled at 200 ° C C: Rolled after holding at 260 ° C for 30 seconds between baths (ii) Finish annealing condition a: After holding at 800 ° C for 50 hours, 10 ° C Temperature rises to 1200 ° C at / h b: Holds at 750 ° C for 100 hours and rises at 10 ° C / h at 1200 ° C c: Holds at 650 ° C for 100 hours and rises to 1200 ° C at 10 ° C / h d: 900 ° C After heating for 50 hours at 10 ℃ / h up to 1200 ℃ e: After holding at 800 ℃ for 5 hours at 1200 ℃ at 10 ℃ / h f: After holding at 800 ℃ for 240 hours at 1200 ℃ at 10 ℃ / h Temperature rise to: g: 800 ℃ 50 hours hold, 100 ℃ / h to 1200 ℃ h: 800 ℃ hold 250 hours, 2.5 ℃ / h to 1200 ℃ i: 800 ℃ to 10 ℃ / h Temperature rise to 1200 ° C As is clear from the table, in the example compatible with the present invention, which was held at 850 ° C. for 50 hours during finish annealing and then heated at 10 ° C./h, a product having a high magnetic flux density was stably obtained.

Example 2 A silicon steel slab having the composition shown in Table 6 was finished into a product having a thickness of 0.30 mm under the same conditions as in Example 1.
However, the cold rolling was performed at normal temperature, and the finish annealing was performed by maintaining the temperature at 800 ° C. for 50 hours and then increasing the temperature to 1200 ° C. at 10 ° C./h.

Example 3 A silicon steel slab having the composition shown in Table 7 was prepared as 1420.
After heating at 0 ° C for 20 minutes, hot rolling was performed to obtain a hot rolled sheet having a thickness of 2.0 mm. The hot rolled sheet was heated at 1050 ° C. for 2 minutes, rapidly cooled by mist injection, and then cold rolled to a thickness of 0.23 mm. After cold rolling, decarburization annealing was performed at 840 ° C for 4 minutes, which also served as recrystallization. After that, MgO was applied and kept at 750 ° C for 100 hours.
Finish annealing was performed by heating to 1200 ° C at a temperature rising rate of ° C / h. The magnetic properties of the product plate thus obtained are as shown in the table, and good magnetic properties are obtained even with a thin plate having a thickness of 0.23 mm.

(Effects of the Invention) According to the present invention, it is possible to manufacture a grain-oriented silicon steel sheet having a high magnetic flux density by a method of stabilizing secondary recrystallization, and to manufacture a silicon steel sheet having excellent magnetic properties in a high yield. .

[Brief description of the drawings]

FIGS. 1 (a) and 1 (b) and FIGS. 2 (A) to 2 (D) are photographs showing a metal structure.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideo Yamagami Inventor Hideo Yamagami 1-chome, Mizushima Kawasaki-dori, Kurashiki City, Okayama Prefecture (No address) Inside the Mizushima Works, Kawasaki Steel Co., Ltd. (56) Reference JP-A-52-77817 (JP, A) ) JP-A-59-35625 (JP, A) JP-A-62-180015 (JP, A) JP-A-62-202024 (JP, A) JP-A-55-47324 (JP, A) JP-A-63- 72825 (JP, A)

Claims (3)

(57) [Claims] C: 0.02 to 0.12 wt%, Si: 2.5 to 4.0 wt%, Mn: 0.03 to 0.15 wt%, sol. Al: 0.01 to 0.05 wt% Sb: 0.01 to 0.20 wt% and N: 0.004 to 0.01 to 0.05 wt% and 0.01 to 0.05 wt% of S and / or Se in total
%, With the balance consisting of iron and unavoidable impurities, hot-rolled, subjected to hot-rolled sheet annealing and quenching, and then subjected to one or two cold-rollings including intermediate annealing In a method for producing a grain-oriented silicon steel sheet comprising a series of steps of performing a rolling reduction of 80% or more and thereafter performing a decarburizing annealing, and then a finish annealing including a secondary recrystallization annealing and a purification annealing, prior to the finish annealing, 700 to 840 After holding for 20 hours or more and 200 hours or less in a temperature range where secondary recrystallization at ℃ does not occur, secondary recrystallization annealing is performed while heating to the temperature range of purification annealing at a heating rate of 5 to 50 ° C / h. And then subjecting it to purification annealing, which is a method for producing a high magnetic flux density grain-oriented silicon steel sheet. 2. C: 0.02 to 0.12 wt%, Si: 2.5 to 4.0 wt%, Mn: 0.03 to 0.15 wt%, sol. Al: 0.01 to 0.05 wt% Sb: 0.01 to 0.20 wt% and N: 0.004 to 0.01 to 0.05 wt% and 0.01 to 0.05 wt% of S and / or Se in total
% And Cu: 0.02-0.20 wt%, Sn: 0.02-0.20 wt% and
Mo: A silicon steel slab containing at least one of 0.005 to 0.05 wt%, the balance being iron and unavoidable impurities is hot-rolled, subjected to hot-rolled sheet annealing and quenching treatment, and then once or intermediately annealed. Final cold rolling rate between two cold rolling
In a method for producing a grain-oriented silicon steel sheet comprising a series of steps of performing decarburizing annealing and then finishing annealing consisting of secondary recrystallization annealing and purifying annealing, at a temperature of 700 to 840 ° C. prior to finish annealing. After holding for 20 hours or more and 200 hours or less in a temperature range where secondary recrystallization does not occur, secondary recrystallization annealing is performed while heating to the temperature range of purification annealing at a heating rate of 5 to 50 ° C / h. A method for producing a high magnetic flux density grain-oriented silicon steel sheet, which is characterized by subjecting it to subsequent purification annealing. 3. The S content is set to 0.01 wt% or less.
Or the production method according to 2.