JPS63176427A - Manufacture of grain-oriented high-silicon steel sheet - Google Patents

Abstract

PURPOSE:To manufacture a grain-oriented high-silicon steel sheet having low iron loss characteristic and also having a high degree of integration, by subjecting a steel slab of specific thickness containing specific percentages of C, Mn, Si, S, Sb, and Se to cold rolling and annealing under specific conditions. CONSTITUTION:A molten steel consisting of, by weight, 0.0005-0.08% C, 0.03-0.14% Mn, 2.6-6.5% Si, 0.007-0.05% S, further 0.01-0.15% Sb and/or 0.005-0.05% Se, and the balance Fe with accompanying impurities is continuously supplied onto a cooling body (e.g., roll) whose cooling surface is renewedly moving, by which the molten metal is cooled down to about 1,000 deg.C at about 10<2>-10<4> deg.C/sec cooling rate and further subjected to rapid solidification by water cooling and the like so as to be formed into a slab of 0.7-3.5mm thickness. Subsequently, this slab is cold-rolled at >=50% draft and then annealed at 600-1,300 deg.C. In this way, the high-silicon steel sheet of {110}<001> orientation excellent in mechanical properties and magnetic properties can be inexpensively obtained.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention contains 2.5 to 6.5% by weight of St, and provides excellent low core loss characteristics (extremely concentrated in the 1101 <001> direction). The present invention relates to a method for manufacturing a unidirectional high-silicon steel sheet with a high degree of strength.

(Prior art) The conventional manufacturing method of (110) <001> unidirectional silicon steel plate is as follows: ■ Continuous casting process into slabs of about 200 mm thickness, for example - Slab high temperature heating process - ■ Hot rolling process - ■ Hot rolled material annealing process - ■ Cold rolling process - ■ Decarburization annealing process - ■
It requires a final high-temperature annealing step and a large number of steps. These steps are necessary to cause only the crystal grains to undergo secondary recrystallization in the (110) <001> orientation during the final high temperature annealing in the final high temperature annealing step (2). In order to cause this secondary recrystallization, it is necessary that precipitates such as MnS and MnSb be finely dispersed in the steel as an inhibitor. However, in the above-mentioned continuous casting process (2), since cooling is very slow, MnS, MnSb, etc. are coarsened during the cooling period following casting. After that, in order to make fine precipitation, process ■
It is necessary to heat the slab to a high temperature in Step 2 and to annealing the hot rolled material in Step ①. In addition, in order to redissolve the precipitate, it is necessary to convert it into the γ phase at a high temperature, and in order to achieve this,
Since approximately 0.02% of C, which is a γ phase forming element, is added,
The upper limit of 5ifi has always been about 3%. Furthermore, since C added to expand the T-phase region deteriorates the magnetic properties, decarburization annealing in the above step (2) is required.

As described above, in the conventional method, complicated steps are required for solid solution and fine dispersion of the inhibitor necessary for secondary recrystallization.Additionally, as the amount of Si added increases, the magnetic properties improve. Although the iron loss value decreases, when the SiM content exceeds 4%, the steel rapidly becomes brittle and becomes difficult to roll. Therefore, S
The upper limit of the amount of i added was limited to about 3%.

Therefore, Tokuko Sho 61-15mm No. 36 and Tokuko Sho 60
As disclosed in No.-38462, Si 4-1
The molten metal containing 0%, etc. is continuously supplied as it is onto a cooling body whose cooling surface moves and renews, and is ultra-quenched to create a high-silicon material with excellent magnetic properties that can be cold-rolled and has rollability and flexibility. A method for manufacturing steel sheets has been proposed. However, according to the method disclosed in Japanese Patent Publication No. 60-38462, for example,
The thickness of one slab produced by continuous casting is in the range of several micrometers to several hundred micrometers, and by making the slab ultra-thin in this way, cold workability is ensured. Moreover, the cold working used at that time is merely employed as a forming means, and there is no suggestion that the magnetic properties are improved by this.

In addition, in Tokuko Sho 61-15mm No. 36, Si: 4 to 1
Contains 0%, and others include Q, Mn, oxygen, sulfur, carbon,
It is disclosed that high-Si steel containing at least one type of nitrogen is ultra-quenched into a ribbon. However, this method directly converts the melt into a finished product or a product close to it; for example, hot working and cold working are virtually not performed, and even when finishing cold working is performed, the reduction rate is low. Limited to 5% or less.

In addition, in Special Publication No. 60-32705, Si 5.0 to 8
．． A (100) in-plane non-oriented high-silicon steel ribbon with excellent magnetic properties and a coercive force tic of 0.10e or less including 0% by weight, etc., and a method for producing the same are disclosed. However, in this method, a ribbon having a thickness of at most 110 μm is directly annealed by performing high-speed cooling, and the magnetic properties obtained are also non-directional.

Although all of these silicon=iE plates produced by conventional methods have high Si content and excellent mechanical and magnetic properties,
There were many requests for even more advanced magnetic properties, and many products were unsatisfactory with these requests.

(Problems to be Solved by the Invention) Here, the purpose of the present invention is to
Contains 6.5% by weight and provides low iron loss characteristics (1101
It is an object of the present invention to provide a method for manufacturing a unidirectional high silicon steel plate having an extremely high degree of integration in the <001> direction.

Furthermore, another object of the present invention is to provide continuous S
A steel with low iron loss properties, constructed by combining the h-building process and the cold rolling process, with a high content of +1101<
An object of the present invention is to propose an economical method for manufacturing a unidirectional high-silicon steel plate having a high degree of integration in the 001> direction.

(Means for Solving the Problems) The present inventors have conducted various studies to solve the problems of the prior art, and have found that in order to achieve fine dispersion of the inhibitor, high-temperature heating of the slab and It is not necessary to re-dissolve inhibitors such as MnS in the hot rolled material annealing process, and such inhibitors can be removed during the annealing process by cold working a thin slab obtained by a continuous casting method using rapid cooling. The present invention was completed based on the knowledge that fine dispersion of can be achieved.

That is, the gist of the present invention is, in weight %, C: 0.0O05-0.08%, Mn: 0.03-0.
14%, Si: 2.5-6.5%, S: 0.0
07 to 0.05%, and further contains Sb: 0.01 to 0.15%, and Se: 0
．． 005 to 0.05%, and optionally at least one of Ni: 1% or less, Cu: 1% or less, and/or Co: 1%
A molten metal containing the following, with the balance consisting of Fe and incidental impurities is continuously fed onto a cooling body whose cooling surface moves and renews, and is rapidly solidified to form a molten metal of 0.7 to 3.5 mm.
An integrated product with low iron loss characteristics, which consists of forming a thick slab, cold rolling the obtained thin slab at a reduction rate of 50% or more, and then annealing at a temperature of 600 to 1300°C. This is a method for producing a high-silicon steel sheet with a high mol <001> orientation.

Thus, when manufacturing a steel sheet containing 4% or more Si, it is impossible to cold-roll it using the conventional method, but according to the present invention, it is possible to rapidly cool it by rolling it to the above-mentioned mm thickness. It is possible to cold-roll even thin slabs with a thickness of 0.7 to 3.5n+m, and by cold-rolling with a rolling reduction of 50% or more and annealing, it is possible to prevent the inhibitor from re-dissolving. It is possible to sufficiently finely disperse the inhibitor without performing recrystallization annealing, and therefore it is possible to sufficiently improve the magnetic properties by recrystallization annealing.

Furthermore, since cold rolling is possible, cold rolling
By applying 0% or more (reduction rate) and repeating heat treatment, a unidirectional high-silicon steel sheet with an extremely high degree of integration and orientation in the (110}<001> direction, which has even better low iron characteristics, is manufactured. It is.

In other words, since it is a thin slab with a thickness of 0.7 to 3.5 mm that has become fine crystals due to rapid cooling, this is reduced by 50%.
By cold rolling with the above rolling reduction ratio, fine dispersion of the inhibitor is effectively achieved. No such effect is seen even after cold working.

(Function) Next, the reason why the steel composition and manufacturing conditions are limited as described above in the present invention will be explained in detail.

Carbon (C) is set at 0.0005% or more because it is difficult to produce molten steel with a concentration of less than o.
08% or less. In the method of the present invention, there is no particular need to contain C, and the preferred range is from o,oos to 0.01%, in which case the decarburization step can be omitted.

Manganese (Mn) is contained at about 0.05% in normal steel manufacturing, and combines with solid solution S to form MnS, suppressing the influence of S on iron loss deterioration and further increasing rolling workability. Therefore, in order to suitably exhibit the effect in the present invention, Mn 0.03 to 0.14%,
Preferably it is 0.05 to 0.12%.

If silicon (Si) is less than 2.5%, high temperature (approximately 1000
~1300℃), and the final annealing temperature was 1000℃.
In the present invention, it is set to 2.5% or more because it is impossible to maintain a temperature higher than ℃ and a low iron loss value cannot be obtained. On the other hand, if it exceeds 6.5%, it becomes brittle and cannot be cold rolled under the above conditions.
It was set to 6.5% or less. , 3 to 5.5% is preferred.

In the present invention, sulfur (S) is S 0.007 to 0.
An addition of 0.05%, preferably 0.01-0.035% is required. In the present invention, S is precipitated as MnS and acts as an inhibitor, so its precipitation form must be sufficiently controlled during rapid solidification (cold rolling).

In the present invention, at least one of antimony (Sb) and selenium (Se) is contained.

Since sb exists in the solidified thin slab, a higher degree of integration (110}〈001〉 silicon steel can be obtained.
0. O1-0.15%, preferably 0.02-0.07%
Contain.

Similarly, Se is also present in the solidified thin slab to obtain a higher degree of integration (110}<001> silicon steel, so the content is 0.005 to 0.05%, preferably 0.01 to 0.00%).
Contain 03%.

At least one of nickel (Ni) and copper (Cu) may be added in an amount of 1% or less each in order to further improve ductility.

In the present invention, 1% or less of Co may be added as necessary to further improve the magnetic properties.

Next, according to the present invention, the molten metal having such a steel composition is continuously supplied onto a cooling body that moves and renews, and is cooled and solidified to produce a slab having a thickness of 0.7 to 3.5 ms. In this case, if the thickness exceeds 3.5 mm, the cooling rate will be insufficient in many cases, while if the thickness is less than 0.7 mm, the cold rolling rate will be insufficient, and the accumulation of grain orientations will not be sufficient.

Here, the "cooling body that moves and updates" is a cooling body that has new cooling surfaces that are sequentially drawn out.

Typical examples of such continuous casting equipment include the so-called twin roll method and single roll method, but the type of equipment is not particularly limited by the present invention.
When producing m-thick slabs, the cooling rate is generally 102 to 10'C/sec up to about 1000℃, and after this, the slabs often separate from the cooling body, in which case they are cooled by air. Speed decreases. Furthermore, after cutting from the cooling body, it is preferable to cool the grass by spraying water or hot water.

In the present invention, fine crystals are formed by rapid cooling as described above, and the cooling rate required for this is preferably 1
02 to 10"C/sec.

The slab obtained in this way is cold rolled at a reduction rate of 50% or more, preferably 60% or more, by repeating cold rolling multiple times with intermediate annealing as necessary, to obtain a plate thickness. 0.15m+++ thickness or more, preferably 0°21101
If the thickness is higher than that, it is considered as a step before final annealing. If the reduction rate is less than 50%, sufficient strain is not applied, so Mn
Fine dispersion of inhibitors such as S, MnSb, MnSe, etc. does not occur sufficiently. Preferably the rolling reduction is 50 to 90%.

Finally, annealing is performed at 1300°C or lower and 600°C or higher for recrystallization to increase the (110) <001> integration degree, 6
If the temperature is lower than 00°C, the annealing effect cannot be obtained. Preferably, this recrystallization annealing is performed at 800 to 1000°C, followed by 1100°C.
Repeat at ℃ or above. This is because a temperature higher than 1300°C can be said to be industrially difficult to process.

In addition, for those with a large amount of carbon Venus, final annealing may be performed as desired after decarburization annealing.

Here, according to the present invention, Mn S , MnSb, Mn
Fine dispersion of inhibitors such as Se and its +1
10} The mechanism of improvement in the accumulation of <001> orientations is considered as follows.

MnS, MnSb, M finely dispersed by rapid cooling
By crushing the nSe precipitates due to strain during cold rolling, MnS, MnSb, and MnS become even finer during recrystallization annealing.
e can be dispersed in the steel. These finely dispersed precipitates act as strong inhibitors, resulting in +110% during recrystallization annealing.
001> crystal grains are preferentially grown, resulting in a high degree of integration (
110}<001> texture is obtained.

As described above, industrially useful mol can be obtained by the method of the present invention.
It becomes possible to suitably manufacture a unidirectional high-silicon steel plate with <OLD orientation.

Next, examples of the present invention will be described.

Example 1 Thin plates having the steel compositions shown in Table 1 were produced using the following two methods.

<Method 1> Pour the molten metal into the gap between twin rolls made of cemented carbide with a diameter of 200 II m rotating at 50 r, p, m, and roll 50 m with a thickness of 1.5 mm.
An ultra-thin slab with a width of m was manufactured. After pickling this slab,
It was subjected to cold rolling of 0.09mm to form a 0.31mm thickness.

<Method 2> Use a mold 50+a+a x 200 mm x 3
After pouring SR into a 00 mm thick slab, it was heated to 1000°C and then gauge forged to a thickness of 25 mm. Then again,
It was heated to 100°C and rolled to 1.5 mm by hot rolling. After further heating to 1200℃ for 10 minutes,
It was rapidly cooled in hot water at 80° C. and finally cold-rolled at a reduction rate of 80% to form a thin plate with a thickness of 0.31.

These thin plates were annealed in a salt bath at 800°C for 5 minutes, and
Next, it was recrystallized. Next, the temperature was raised to 1200°C at a temperature increase rate of 50°C/h in a N atmosphere, and soaking annealing was performed at 1200°C for 3 hours. After that, we investigated the existence of secondary recrystallized grains that had grown to a size of 5 mm or more by diluted tJi# corrosion, and then used the etch pit method to investigate the presence of secondary recrystallized grains of 5 mm or more (ILOI <001> orientation) The results are shown in Table 2.

As is clear from Table 2, for types B, C, and D, which are outside the range of formation specified in the present invention, the height of the crystal grains in the +1101 <001> orientation, which could not be achieved by the conventional rolling method. An accumulation of (110+ <Oat
It can be seen that a silicon steel plate with a high degree of integration in the > orientation can be obtained. In addition, steel type A outside the composition range according to the present invention has a low Si content, so even if the process according to the present invention is performed, T phase precipitation occurs during final annealing and secondary recrystallization does not occur, and steel type E
Because of the high Si content, cold rolling was impossible and comparison could not be made.

From Table 2, it is clear that according to the method of the present invention, a silicon steel plate with an extremely high degree of integration in the [110}<001> orientation can be obtained compared to the conventional rolling method.

(Note 11; Outside the scope of the present invention Table 2 Method 2-Low 11 Example 2 Thin plates having the compositions shown in Table 3 were manufactured by the following method.

The molten metal was poured into the gap between twin copper rolls with a diameter of 300 I rotating at 100 r, p, n+, to produce a thin slab with a thickness of 2.0 mm. Thereafter, scale was removed by pickling with sulfuric acid, and the plate was cold rolled to a predetermined thickness (0.2 to 0.4 mm).

The thin plate thus obtained was annealed at 850°C for 3 minutes in a salt bath for primary recrystallization, and then heated to 1150°C at a heating rate of 50°C/h in a 50% N, -H atmosphere. The temperature was raised and annealing was performed at 1150°C for 5 hours. In order to measure the magnetic properties in the rolling direction from this thin plate, 25 cm Epstein iron TP test specimens were punched out and strained by annealing at 850°C for 10 minutes.
Table 4 shows the results of measuring iron loss values using i-containing unidirectional silicon steel sheets. From this Table 4, it can be easily understood that by the method of the present invention, an excellent electromagnetic steel sheet having a lower iron loss value than the conventional unidirectional silicon steel sheet can be manufactured.

Table 3 (wt%) Table 4 Example 3 Using steel type G in Table 3, molten metal was injected into the gap between twin cemented carbide rolls with a diameter of 200+*m rotating at 150 r, p, s. and (0,3,o,
s, 0.7; 1.5.2°5, 3.0.4.0.5
．． Thin slabs of 8 types of 0LI11) were manufactured.

After that, scale was removed by sulfuric acid pickling, and the reduction rate was 75.
% cold rolling and then in a salt bath at 800°C for 10
First crystallize by annealing for 1 minute, then 30℃ in 2 atmosphere.
The temperature was raised to 1200°C at a heating rate of /h and annealed at 1200°C for 5 hours.

Figure 1 shows the results of measuring the ratio of crystal grains with (110}<001> orientation on these samples using the etch focus method.From this figure, it can be seen that the thickness of the thin slab was 0.7~3. 5
It can be seen that the crystal grains with the (110}<001> orientation increase in the am range, and the ratio is ＼90 to 100%.

Example 4 Using steel type H in Table 3, molten metal was injected into the gap between twin cemented carbide rolls with a diameter of 200 m rotating at 20 Or, p, n+, and a thin slab with a thickness of 1.5 mm was made. Manufactured. Next, scale was removed by sulfuric acid pickling, and the reduction rate was 30 to 9.
0% (30, 38, 45, 50-60, 70, 80,
90% of 8 types) After cold rolling, 50℃
The temperature was raised to 1200°C at a heating rate of /h, and soaking annealing was performed at 1200°C for 5 hours.

For these samples, the ratio of crystal grains in the (110}<001> direction was measured by the etch focus method.
As shown in the figure. From this figure 2, it is clear that the cold rolling rate is 50%.
From the above, it can be seen that the crystal grain ratio of the (110) <001> orientation increases, and the ratio is 170 to 100%, and the degree of integration increases.

(Effects of the Invention) As described above, the unidirectional high-silicon steel sheet manufactured by the method according to the present invention is more highly superior to the conventional unidirectional silicon steel sheet. It is expected to be widely used as an electrical steel sheet that has mechanical properties and excellent magnetic properties. In addition, since we have adopted a method of manufacturing thin slabs using a rapid cooling method on a moving and renewing cooling body, we can omit the heat treatment process that was previously thought to be necessary, making it significantly cheaper than conventional methods and reducing the Si content. It is possible to produce a unidirectional high-silicon steel sheet with high and low core loss characteristics, which is extremely useful industrially.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the slab thickness after rapid cooling of the unidirectional high-silicon steel sheet of the present invention and the ratio of crystal grains in the (110}<001> orientation. It is a graph showing the relationship between each cold rolling rate and the crystal grain ratio of the (110}<001> orientation in the invention.

Claims (4)

[Claims] (1) In weight%, C: 0.0005-0.08%, Mn: 0.03-0.
14%, Si: 2.5-6.5%, S: 0.007-0
．． 05%, further Sb: 0.01 to 0.15%, and Se: 0.05%.
005 to 0.05%,
A molten metal having a composition in which the balance consists of Fe and incidental impurities is continuously supplied onto a cooling body whose cooling surface moves and renews, and is rapidly solidified to a temperature of 0.7 to 3.5
Obtaining a slab with a thickness of mm, and cold rolling the obtained slab at a reduction rate of 50% or more, and then rolling a slab with a thickness of 600 to 13
A method for producing a highly integrated {110}<001> oriented high-silicon steel sheet with low core loss characteristics, comprising annealing at a temperature of 00°C. (2) In weight%, C: 0.0005-0.08%, Mn: 0.03-0.
14%, Si: 2.5-6.5%, S: 0.007-0
．． 05%, further Sb: 0.01 to 0.15%, and Se: 0.05%.
005 to 0.05%, and at least one of Ni: 1% or less and Cu: 1% or less, with the balance consisting of Fe and incidental impurities. It is continuously supplied onto a cooling body whose surface moves and renews, and is rapidly solidified to a temperature of 0.7 to 2.0.
Obtaining a slab with a thickness of mm, and cold rolling the obtained slab at a reduction rate of 50% or more, and then rolling a slab with a thickness of 600 to 13
A method for producing a highly integrated {110}<001> oriented high-silicon steel sheet with low core loss characteristics, comprising annealing at a temperature of 00°C. (3) In weight%, C: 0.0005-0.08%, Mn: 0.03-0.
14%, Si: 2.5-6.5%, S: 0.007-0
．． 05%, further Sb: 0.01 to 0.15%, and Se: 0.05%.
0.005 to 0.05% and Co: 1% or less, with the balance consisting of Fe and incidental impurities. Supply and rapidly solidify, 0.7 to 3.5
Obtaining a slab with a thickness of mm, and cold rolling the obtained slab at a reduction rate of 50% or more, and then rolling a slab with a thickness of 600 to 13
A method for producing a highly integrated {110}<001> oriented high-silicon steel sheet with low core loss characteristics, comprising annealing at a temperature of 00°C. (4) In weight%, C: 0.0005-0.08%, Mn: 0.03-0.
14%, Si: 2.5-6.5%, S: 0.007-0
．． 05%, further Sb: 0.01 to 0.15%, and Se: 0.05%.
005 to 0.05%, at least one of Ni: 1% or less, and Cu: 1% or less, and Co: 1% or less, with the balance consisting of Fe and incidental impurities. A molten metal having a 0.7 to 3.5
Obtaining a slab with a thickness of mm, and cold rolling the obtained slab at a reduction rate of 50% or more, and then rolling a slab with a thickness of 600 to 13
A method for producing a highly integrated {110}<001> oriented high-silicon steel sheet with low core loss characteristics, comprising annealing at a temperature of 00°C.