JPH0598339A - Production of grain oriented silicon steel material - Google Patents

Abstract

PURPOSE:To provide a producing method for grain oriented silicon steel material which can realize continuous casting without variation in the components in the longitudinal direction of a cast slab, as favorable in the case of particularly applying to the production of the grain oriented silicon steel containing Al and Sb and having extremely high magnetic flux density by the continuous casting method. CONSTITUTION:Slag components in a ladle incorporating the molten steel containing 2.5-4.5wt% Si, 0.01-0.15wt% Al and 0.005-0.08wt% Sb is adjusted in the range of <=0.25 Al2O3/SiO2,<=0.20 Al2O3/CaO and <=10wt.% T.Fe. By this method, i.e., by supplying the molten steel after the adjustment of the slag components in the ladle into the continuous casting, the cast slab without any variation in the components in the longitudinal direction is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for melting a grain-oriented silicon steel material for continuous casting of grain-oriented silicon steel containing Al and Sb and having an extremely high magnetic flux density.

[0002]

2. Description of the Related Art Grained silicon steel sheets have magnetic properties
High magnetic flux density and low iron loss are required.
Due to advances in manufacturing technology in recent years, for example, for a steel sheet with a thickness of 0.23 mm, the magnetic flux density B ₈ (value at a magnetizing force of 800 A / m): 1.
92T was obtained, and the iron loss characteristics W _17/50 (50 Hz, 1.
It is also possible to produce an excellent product with a maximum magnetization of 7T) of 0.90 w / kg on an industrial scale.

The material having such excellent magnetic properties is composed of a crystal structure in which the <001> orientation, which is the easy axis of iron, is highly aligned in the rolling direction of the steel sheet, and such a texture is , During the final finishing annealing during the manufacturing process of grain-oriented silicon steel sheet, it is formed through the phenomenon called secondary recrystallization in which the crystal grains having the (110) 001 orientation, which is the so-called Goss orientation, grow preferentially. To be done. The basic requirement for sufficiently growing the secondary recrystallized grains in the (110) 001 orientation is to suppress the growth of crystal grains having an unfavorable orientation other than the (110) 001 orientation in the secondary recrystallization process. It is a well-known fact that the existence of an inhibitor that inhibits the formation of a primary recrystallized structure suitable for sufficient development of secondary recrystallized grains in the (110) 001 orientation is essential.

Here, Mn is generally used as an inhibitor.
Fine precipitates such as S, MnSe, and AlN are used, and in addition to these, grain boundary segregation type elements such as Sb and Sn as disclosed in JP-B-51-13469 and JP-A-54-32412 are added. Multiple additions have been used to reinforce the effect of inhibitors.

By the way, in general, those having MnS or MnSe as a main inhibitor have been advantageous in reducing iron loss because of their small secondary recrystallized grain size. In recent years, however, laser irradiation method and plasma jet method have been used. Since it became possible to artificially introduce pseudo-grain boundaries to subdivide magnetic domains, the advantage of the small secondary recrystallized grain size decreased,
The advantage of high magnetic flux density has increased.

A method for obtaining a grain-oriented silicon steel sheet having a high magnetic flux density has been known for a long time. For example, as described in Japanese Patent Publication No. 46-23820, AlN is contained in the steel as an inhibitor component. It is said that it can be manufactured by the above three-point bonding, in which the cooling of the annealing before the final cold rolling is rapidly cooled to precipitate AlN, and the rolling reduction of the final cold rolling is set to 80 to 95% and the high pressure rolling reduction.

The above method has a drawback that the magnetic flux density rapidly deteriorates when the plate thickness of the product becomes thin.
It was extremely difficult to stably produce a product of B ₈ ≧ 1.94 with the following products. On the other hand, the inventors
It was found that by adding Sb to the grain-oriented silicon steel sheet material whose main inhibitor is and improving the finish annealing method, a material with an extremely high magnetic flux density can be obtained even when the final sheet thickness of the steel sheet is small, It was previously proposed in Japanese Patent Laid-Open No. 2-115319. However, it is not always easy to industrially produce a material having a high magnetic flux density by the above method.

[0008]

Therefore, as a result of investigating the cause by taking samples of many hot-rolled coils, the inventors found that the values of Si and Sb depend on the sample even in the same melt charge. Was found to fluctuate greatly. Further, Se in steel containing Se also fluctuated greatly like Si and Sb. Here, Si directly affects the value of iron loss,
In addition, since it affects the γ-transformation rate during high temperature annealing in the intermediate process, its content must be strictly controlled. Sb
Segregates at grain boundaries and controls the size of precipitated carbide during cooling of hot-rolled sheet annealing and intermediate annealing, and suppresses nitriding and denitrification in these annealing, decarburization / primary recrystallization annealing and final finish annealing, A certain amount is necessary to maintain the stability of precipitated AlN in steel against the atmosphere, and this must also be strictly controlled. Furthermore, since Se directly acts as an inhibitor of MnSe, it must be strictly controlled when it is added.

By the way, in the production of grain-oriented silicon steel slabs by the continuous casting method, since it takes 1 to 2 hours to cast one charge, it is known that the components vary greatly after casting. For example, JP-B-58-9125 discloses that in continuous casting of grain-oriented electrical steel, the final slab has 0.005 wt% sol.Al (hereinafter simply referred to as%) compared to the slab obtained in the first half of casting. ), S is reduced by 0.005%, and the magnetic properties of the product after secondary recrystallization are remarkably deteriorated. Furthermore, the cause is that casting of a long time causes molten steel to react with slag (slag). It is described that when the amount of slag is small, molten steel and air directly react with each other. See also
Japanese Laid-Open Patent Publication No. 4207 describes that in casting of molten steel for electromagnetic steel sheets, in continuous casting and bottom pouring ingot method, since it takes an extremely long time from the start of pouring to the completion of pouring, Al is reduced by 0.007%. Also in this case, it is stated that the cause is that Al in the molten steel reacts with a metal oxide whose bonding force with oxygen is weaker than that of Al in the slag, and Al becomes an oxide and is lost from the molten steel. ing.

In order to address such a problem, Japanese Examined Patent Publication No. 58-9125 discloses that CaO, of the slag composition in the ladle containing molten steel,
The SiO ₂ and Al ₂ O ₃ components are controlled to have Al ₂ O ₃ / SiO ₂ weight ratio and CaO / SiO ₂ weight ratio in the ranges of 0.25 to 2.0, respectively, to suppress the fluctuations of the Al component and the S component. In JP-A-59-34207, the slag component in the ladle holding molten steel is (% Al ₂ O ₃ ) / (% CaO) 1.0 or more and (% Al ₂ O ₃ ) / (% Si
It is disclosed that the fluctuation of Al component is suppressed by adjusting O ₂ ) to be 1.0 or more. These techniques were effective in continuous casting of ordinary Al-containing silicon steel, but in the continuous casting of Sb-containing molten steel for grain-oriented silicon steel, the Al content was increased. Occurs.

FIG. 1 shows C: 0.08%, Si: 3.27%, Mn: 0.07.
This is an example showing changes in the amounts of Al and Si and corresponding changes in product characteristics when molten steel containing 83% by mass and N: 83 ppm is held in a ladle and continuously cast for 1 hour. The slag in the ladle was added with bauxite at the time of tapping, and Al ₂ O ₃ : 33%, SiO ₂ : 25%,
CaO: adjusted to 28%, Al ₂ O ₃ / SiO ₂ = 1.32, Al ₂ O ₃ / CaO = 1.1
8 and CaO / SiO ₂ = 1.12.

From FIG. 1, the Al content is increased with the passage of casting time.
It can be seen that the Si content decreases while the ratio increases.
In particular, the products from the middle stage to the latter stage of casting have an Al content
There is a problem in that it is too high and causes secondary recrystallization failure.
This is clearly the Al in the slag ₂O₃The Si in the molten steel
This is because the oxidized and reduced Al melts into the molten steel.
It Why does this phenomenon occur in molten steel containing Sb?
It is unknown whether the Si content in the molten steel is compared with the Al content.
And the activity of the oxide is increased by Sb.
It is thought that the change is related. Slag
Al inside₂O₃The content of Al decreases₂O₃/ SiO₂To 0.25
And Al₂O₃If the CaO content is 0.20 or less, the Al content will increase.
Therefore, the secondary recrystallization failure can be avoided, but in the process of casting
Therefore, the amount of Si and Sb decreases, and with molten steel containing Se,
If the Se amount also decreases, the above-mentioned problems may occur again.
Becomes

The present invention is particularly suitable for producing a grain-oriented silicon steel containing Al and Sb and having an extremely high magnetic flux density by a continuous casting method, that is, a continuous material having no component fluctuation in the longitudinal direction of the slab. The purpose of the present invention is to propose a smelting method for directional silicon steel material that can realize casting.

[0014]

Means for Solving the Problems The inventors of the present invention have succeeded in continuous casting of molten steel for grain-oriented silicon steel containing Al and Sb in combination.
As a result of diligent study on the technology for suppressing the fluctuation of the contents of Al, Si, Sb and Se, the slag composition in the ladle containing molten steel was determined to be Al ₂ O 3.
_With respect to ₃ , ₃ , SiO ₂ and CaO, the weight ratios of Al ₂ O ₃ / SiO ₂ to 0.25 or less and Al ₂ O ₃ / CaO to 0.20 or less, T.
We obtained a new finding that the fluctuation of slab components such as Al, Si, Sb. Se can be suppressed by setting Fe to 10% or less.

That is, the present invention is Si: 2.5-4.5%,
Al: 0.01 to 0.15% and Sb: 0.005 to 0.08% when subjecting the molten steel to continuous casting, the slag component in the ladle containing the molten steel was Al ₂ O ₃ / SiO ₂ ≤ 0.25 Al ₂ O ₃ / CaO ≤ 0.20 and T. Fe ≤ 10% in the range. It is a method for melting grain-oriented silicon steel material. Here, T. Fe indicates the total amount of Fe contained in FeO, Fe ₂ O _3, etc. (total Fe content).

[0016] In carrying out the operation, the slag thickness is changed from 50 mm.
Control to 150 mm and 0.5% Na ₂ O or MgO in the slag.
Additions in the range of -10% are advantageously suitable.

The present invention will be described in detail below based on the experimental results that led to the origin of the present invention. In order to quantitatively evaluate the amount of decrease in molten steel composition, the inventors have made 150 tons of molten steel, cast it with a continuous casting machine at a constant rate for 1 hour, and finish the casting. The difference (Cf-Ci) between the component content Cf of the slab at that time and the component content Ci of the slab at the start of injection was investigated as the amount of change in the component. That is, molten steel is C: 0.069 to 0.082%, Si: 3.
23 to 3.39%, Mn: 0.062 to 0.075%, Se: 0.017 to 0.
021%, Al: 0.018 to 0.027%, Sb: 0.022 to 0.027
% And N: Amount of change of Al, Si, Sb and Se when various compositions in the range of 68 to 89 ppm are used and the slag composition in the ladle containing each molten steel is changed and cast. investigated.
The survey results are shown in FIGS. 2 to 5 for each component.

First, as shown in FIG. 2, 0.25 Al ₂ O ₃ / SiO ₂ was added.
It is understood that the increase of Al can be suppressed by setting the ratio below and the ratio of Al ₂ O ₃ / CaO to 0.20 or less. However, in the case of Si shown in FIG. 3, when Al ₂ O ₃ / SiO ₂ ≦ 0.25 and Al ₂ O ₃ / CaO ≦ 0.20, the fluctuation amount (absolute value of the change amount) is reduced,
A decrease of 0.02 to 0.05% is still recognized, and as shown in FIGS. 4 and 5, in Sb and Se, on the contrary, the variation (absolute value of variation) tends to increase.

As a result of pursuing the causes of the above fluctuations of Si, Sb and Se, the inventors have found a strong correlation between T.Fe in the slag and the amounts of changes of Si, Sb and Se. That is, in FIGS. 6 to 8, among the experimental data whose results are shown in FIGS. 2 to 5 above, Al ₂ O ₃ /
For SiO ₂ ≤ 0.25 and Al ₂ O ₃ / CaO ≤ 0.20 T.Fe and S
As shown in the relationship with the amount of change in i, Sb, and Se, the amount of change in Si, Sb, and Se also decreases as the T.Fe amount decreases.

T.Fe in the slag is FeO, Fe ₂ O _3, etc.,
It is usually contained in the range of 1% to 30%. This is generated mainly by the oxidation of iron by decarburization blowing in a converter. Since CaO is used as an auxiliary raw material in the converter for the slag component, the ratio of T.Fe and CaO is extremely high. In order to reduce the ratio of T.Fe, in addition to the method of blowing in the converter by the down-blowing method, there is a method of suppressing the amount of slag mixed when pouring molten steel into the ladle at the time of tapping. It is valid. Because Si and Al are added to the molten steel after this, the T.Fe in the slag decreases due to the mixing of SiO ₂ and Al ₂ O ₃ generated at this time into the slag, and the mixing of CaO added. Because it does. When T.Fe is high, the decrease of Si in slag progresses because molten steel Si due to FeO and Fe ₂ O _{3 in} slag
The cause of the progress of the decrease of Sb and Se is unknown. Probably related to slag liquidity, Sb
And Se are considered to be captured in the slag.

Next, molten steel having the same composition as in the above experiment was similarly cast by continuous casting. The slab composition at this time is Al ₂ O ₃ / SiO ₂ : 0.10 to 0.20, Al ₂ O ₃ / CaO: 0.10 to 0.20.
And T.Fe: 5-10%. And part of it was added to the slag by adding soda ash or MgO during tapping.
Na ₂ O and MgO were added, and the thickness of the slag that covered the molten steel was changed for some other parts, and continuous casting was performed for each, and the amount of change in the composition was measured. The measurement results are shown in FIGS.

From FIG. 9, it can be seen that the change amount of Si, Sb, Se becomes extremely small in the range of 50 to 150 mm of slag thickness. If the slag thickness is thin, the amount of iron oxide in the slag will decrease, so this adverse effect will be reduced, but if it is less than 50 mm, the probability that molten steel will come into contact with the atmosphere will increase, leading to an increase in T.Fe. it is conceivable that.

Further, FIG. 10 shows the effect of Na ₂ O in the slag, and the variation of Si, Sb and Se decreases as the content of Ma ₂ O increases. Furthermore, Fig. 11 shows the effect of MgO in the slag, and as with Na ₂ O, the variation of Si, Sb, Se decreases as the content increases. Note that
The reason why the variation of Si, Sb, Se is reduced by the increase of the content of Na ₂ O or MgO is that the increase of Na ₂ O and MgO decreases the fluidity of the slag. This is probably because the uptake into the slag is suppressed. However, 10%
The above contents are not preferable because they drastically reduce the fluidity of the slag and make it difficult to remove the sludge from the ladle after the casting.

[0024]

[Function] The grain-oriented silicon steel material in the present invention is made of Si,
The composition contains Al and Sb. First, if Si is too small, the electric resistance becomes small and good iron loss characteristics cannot be obtained, while if it is too large, cold rolling becomes difficult.
The range is 4.5%. In addition to this, C is necessary for improving the hot rolling structure, but if it is too much, decarburization becomes difficult, so 0.035
It is preferably contained in the range of about 0.090%.

Also, Al is essential as an inhibitor-forming component, that is, for the inhibitor, AlN is particularly advantageous for obtaining a high magnetic flux density. Therefore, in the present invention, AlN is used as the main inhibitor, but too many. On the contrary, since fine precipitation becomes difficult, Al:
It is preferably in the range of 0.01 to 0.15%, while N is preferably in the range of 0.0030 to 0.020%. The term "major inhibitor" as used herein means that, when it is lacking, secondary recrystallization cannot be expressed.

As the inhibitor-forming component, S, Se
May be supplementarily contained. That is, S or Se is MnS
Alternatively, it precipitates as MnSe and is effective as an inhibitor. Among them, MnSe is preferable because it has a strong suppressing effect even when the final finished plate thickness becomes thin. The range of S and Se suitable for finely precipitating such MnS and MnSe is about 0.01 to 0.40% in both cases of single and combined use. It should be noted that Mn becomes an inhibitor component as described above, but if it is too much, solution treatment is difficult, so the range of 0.05 to 0.15% is preferable.

Further, in the present invention, it is indispensable to contain Sb in the steel, and by containing 0.005 to 0.08% of Sb, a product having an extremely high magnetic flux density can be obtained even when the steel plate is thin. Be done. This is because the segregation effect of Sb on the steel plate surface and grain boundaries effectively acts, and the inhibitor suppressing effect is maintained even when the steel plate thickness is small.

In addition to the above, in order to improve magnetism, C
Inhibitor-reinforcing elements such as u, Cr, Bi, Sn, B and Ge can be added as appropriate, and the range thereof may be a known range. In order to prevent surface defects caused by hot embrittlement and suppress recrystallization in hot rolling and finish rolling, M in the range of 0.005 to 0.020% is used.
o Addition is preferred.

Steel having such a composition is melted by a known manufacturing method and then stored in a ladle for use in continuous casting. Here, among the slag compositions in the ladle, Al ₂ O ₃ , SiO ₂ and CaO are contained. The weight ratio of Al ₂ O ₃ / SiO ₂ ≤ 0.25 Al ₂ O ₃ / CaO ≤ 0.20 is regulated, and it is the essence of the present invention that T. Fe is T. Fe ≤ 10%. It is possible to suppress the component fluctuation in the length direction.

Al ₂ O ₃ / SiO ₂ exceeds 0.25 or Al ₂ O ₃ /
When CaO exceeds 0.20, the fluctuation of Al becomes large and T.Fe becomes
If it exceeds 1.0%, the fluctuation amount of Si, Sb and Se becomes large. Al
_{Since 2} O ₃ contains Al and is generated by the oxidation of Al introduced into molten steel, it is not necessary to treat aluminum oxide such as bauxite at the time of tapping at all, and conversely Al ₂ It is not preferable because it increases the O ₃ content.
When the content of Al ₂ O ₃ in the slag is high, it is necessary to add CaO or SiO ₂ to reduce the above ratio.

In order to reduce T.Fe, the amount of lime, which is an auxiliary material in converter blowing, should be increased or lower blowing should be performed, or the slag mixed in the ladle during tapping should be removed. It can be controlled by limiting the amount and at the same time adding calcined lime.

Further, in the present invention, the thickness of the slag in the ladle is limited to 50 mm to 150 mm, or Na ₂ O is contained in the slag.
Or, by containing MgO in the range of 0.5 to 10%,
It is possible to more effectively suppress the variation amount of the component in the length direction of the cast slab. That is, the slag thickness is 50 mm
A thinner layer promotes atmospheric oxidation of molten steel, while a thicker layer than 150 mm promotes fluctuations in the Si, Sb, and Se composition of the slab.
When the content of Na ₂ O or MgO is less than 0.5%, the effect of suppressing the component fluctuation is poor, while when it exceeds 10%, the fluidity of the slag is deteriorated and the workability is extremely deteriorated, which is not desirable. The slag thickness can be adjusted by adjusting the amount of slag mixed in the ladle with molten steel in the latter half of tapping, or by adding CaO especially when the slag in the ladle is thin. Done. The method of adding Na ₂ O component to the slag can be realized by adding soda ash during tapping, and similarly, the MgO component can be realized by adding MgO, dolomite, or the like.

The slab obtained through these steps is
A known manufacturing method of a grain-oriented silicon steel sheet containing Sb is applied, and the slab that is recompressed is heated at a high temperature if necessary and hot-rolled. And the steel strip after hot rolling is cold-rolled once,
Alternatively, the final plate thickness is obtained by cold rolling twice with intermediate annealing. The annealing before the final cold rolling is preferably performed at a high temperature of 850 to 1200 ° C for solutionizing AlN, and after annealing, it is preferable to perform a rapid cooling treatment to 500 ° C for precipitation of AlN. The cooling here may be performed by immersing in hot water and rapidly cooling to a low temperature as shown in, for example, JP-B-46-23820, but in the steel containing Sb, at least 500 ° C. It is advantageous to rapidly cool the solution and gradually cool it in a temperature range of 500 to 200 ° C or to add strain to gradually cool it.

Regarding the final cold rolling reduction rate, it is preferable to use a high pressure reduction rate in order to obtain a high magnetic flux density as known in the art. Therefore, the single reduction rolling rate and the final cold rolling reduction in the double rolling method are performed. The reduction rate of each is 80 to 95%.
This is because if the rolling reduction is less than 80%, a high magnetic flux density cannot be obtained, while if it exceeds 95%, secondary recrystallization becomes difficult.

Note that performing the aging treatment during the final cold rolling is advantageous in reducing the iron loss of the product. Especially Sb
The component system of the present invention containing is excellent in that the magnetic flux density is remarkably improved by a single aging treatment even for a short time. The steel sheet after the final rolling is subjected to degreasing treatment, and then subjected to decarburization and primary recrystallization annealing. Then Mg
After applying an annealing separator containing O as a main component, it is wound into a coil and subjected to final annealing, and then an insulating coating is applied if necessary, but sometimes using a laser or plasma, It is also possible to perform the magnetic domain subdivision processing by other methods.

[0036]

【Example】

Example 1 For molten steel for a silicon steel plate melted in an upper / lower blowing converter, 3.5 kg /
At the rate of t, CaO was added to the ladle during tapping, and FeSi alloy was also added at the same time. Then, in a vacuum degassing (RH) furnace, C, Si, Mn,
After adjusting Al, Se, Mo, Sb, and N, casting was performed at a constant speed by a continuous casting machine while adjusting the components of the slag in the ladle. The composition of molten steel immediately after RH is C: 0.075%, Si:
3.32%, Mn: 0.070%, Al: 0.027%, Se: 0.018%, M
o: 0.011%, Sb: 0.025%, N: 89 ppm, and the slag composition is T.Fe 3%, Al ₂ O ₃ 7%, SiO ₂ 30%, CaO 48
%, And the thickness of the slag was 80 mm. Molten steel was poured into the continuous casting tundish from the ladle over 70 minutes, and slab samples corresponding to each casting time were collected and analyzed every 10 minutes. The results of this analysis are shown in Table 1.

As a comparison, FeSi alloy and bauxite were added to the steel output for the silicon steel sheet melted in the top-blown converter, and C, Si, Al, Se, Mo, Sb, N were also added in the RH furnace. Adjustments were made and casting was carried out at a constant speed on a continuous casting machine. The composition of molten steel immediately after RH is C: 0.078%, Si: 3.30%, Mn: 0.0
68%, Al: 0.026%, Se: 0.019%, Mo: 0.012%, Sb: 0.026
%, N: 92 ppm, and the slag composition is T.Fe 13%, Al
₂ O ₃ 11%, SiO ₂ 28%, CaO 32%, and the slag had a thickness of 160 mm. Molten steel was poured into the continuous casting tundish from the ladle over 70 minutes, and slab samples corresponding to each casting time were collected and analyzed every 10 minutes. The results of this analysis are also shown in Table 1 as a comparative example.

[0038]

[Table 1]

EXAMPLE 2 4.2 kg /
CaO containing 20% soda ash was added to the ladle during tapping at a rate of t.
FeSi alloy was also added at the same time. Then vacuum degassing
(RH) furnace adjusts C, Si, Mn, Al, Se, Mo, Sb, N
After that, the continuous casting machine while adjusting the composition of the slag in the ladle
Was cast at a constant speed. Here, the composition of molten steel immediately after RH
Is C: 0.069%, Si: 3.25%, Mn: 0.075%, Al: 0.
025%, Mo: 0.012%, Sb: 0.025%, N: 72 ppm,
The slag composition is T.Fe 6%, Al₂O ₃4%, SiO₂ 32
%, CaO 41%, Na₂O 2%, slag thickness is 170m
It was m. Molten steel is cast continuously from the ladle for 60 minutes.
Slab test that injects every 10 minutes for each casting time.
The material was collected and analyzed. The results of this analysis are shown in Table 2.

[0040]

[Table 2]

Example 3 4.5 kg / mol of molten steel for a silicon steel plate melted in an upper / lower blowing converter
CaO containing 10% of MgO was added to the ladle during tapping at a ratio of t, and at the same time FeSi alloy was also added. At this time, the amount of tapped steel was also limited in order to avoid mixing of slag into the molten steel. Next, after adjusting C, Si, Mn, Al, Se, Mo, Sb, N in a vacuum degassing (RH) furnace, casting at a constant speed with a continuous casting machine while adjusting the composition of the slag in the ladle. did. The composition of molten steel immediately after RH is C: 0.068%, Si: 3.25%, Mn: 0.065%, A
l: 0.023%, Se: 0.020%, Sb: 0.027%, N: 82 ppm, and the slag composition is T.Fe 1.5%, Al ₂ O ₃ 3%,
SiO _{2 was} 35%, CaO was 48%, MgO was 5%, and the thickness of the slag was 120 mm. Molten steel was poured into the continuous casting tundish from the ladle over 60 minutes, and slab samples corresponding to each casting time were collected and analyzed every 10 minutes. The results of this analysis are shown in Table 3.

Further, as a comparison, FeSi alloy was added together with 2.5 kg / t of CaO in the steel output for the silicon steel sheet melted in the top-blown converter, and C, Si, Al, Se and Mo were also added in the RH furnace. , Sb, N were adjusted, and casting was performed at a constant speed with a continuous casting machine. The composition of molten steel immediately after RH is C: 0.070%, Si: 3.27%,
Mn: 0.065%, Al: 0.024%, Se: 0.019%, Sb: 0.026%, N:
80 ppm, and the slag composition is T.Fe 13%, Al ₂ O ₃ 11
%, SiO ₂ 28%, CaO 32%, slag thickness is 150 mm
Met. Molten steel was poured into the continuous casting tundish from the ladle over 60 minutes, and slab samples corresponding to each casting time every 10 minutes were collected and analyzed. The results of this analysis are also shown in Table 3 as a comparative example.

[0043]

[Table 3]

[0044]

INDUSTRIAL APPLICABILITY By subjecting the molten steel obtained by adjusting the slag composition in the ladle according to the present invention to continuous casting, it is possible to provide a cast slab without fluctuations in the composition in the length direction, and thus to obtain a product with fluctuations in composition. It is possible to prevent deterioration of magnetic characteristics.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between changes in Al and Si amounts and corresponding changes in product characteristics.

FIG. 2 is a graph showing the relationship between Al ₂ O ₃ / SiO ₂ and Al ₂ O ₃ / CaO and changes in the amount of Al.

FIG. 3 is a graph showing the relationship between Al ₂ O ₃ / SiO ₂ and Al ₂ O ₃ / CaO and changes in the amount of Si.

FIG. 4 is a graph showing the relationship between Al ₂ O ₃ / SiO ₂ and Al ₂ O ₃ / CaO and changes in the amount of Sb.

FIG. 5 is a graph showing the relationship between Al ₂ O ₃ / SiO ₂ and Al ₂ O ₃ / CaO and changes in the amount of Se.

FIG. 6 is a graph showing the relationship between T. Fe and changes in Si content.

FIG. 7 is a graph showing the relationship between T. Fe and changes in the amount of Sb.

FIG. 8 is a graph showing the relationship between T. Fe and changes in Se content.

FIG. 9 is a graph showing the relationship between slag thickness and changes in Si, Sb, and Se amounts.

FIG. 10 is a graph showing the relationship between the Na ₂ O content and changes in the amounts of Si, Sb, and Se.

FIG. 11 is a graph showing the relationship between MgO content and changes in Si, Sb, and Se contents.

Claims (3)

[Claims] 1. Si: 2.5-4.5 wt%, Al: 0.01-0.15
When the molten steel containing wt% and Sb: 0.005 to 0.08 wt% is subjected to continuous casting, the slag component in the ladle containing the molten steel is Al ₂ O ₃ / SiO ₂ ≤ 0.25 Al ₂ O ₃ / CaO ≤ A melting method for a grain-oriented silicon steel material, characterized in that the content is adjusted to 0.20 and T. Fe ≤ 10 wt%. 2. The method according to claim 1, wherein the slag has a thickness of 50 to 150 mm. 3. The method according to claim 1, wherein Na ₂ O or MgO is added to the slag in the range of 0.5 to 10 wt%.