JP3213699B2 - Nozzle for continuous casting of steel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nozzle for continuous casting of steel, such as an immersion nozzle and a long nozzle.

[0002]

In continuous casting of the Prior Art steel, conventionally, Al ₂ O ₃ -SiO ₂ quality nozzles having excellent spalling resistance is most widely used. However, when this material nozzle is used for casting Al-killed steel, there arises a problem of nozzle blockage due to adhesion of Al ₂ O ₃ inclusions in molten steel. Also,
When used for casting high oxygen content steel, high Mn content steel, stainless steel, etc., the problem of nozzle erosion occurs. Clogging and melting of the nozzle not only shortens the service life of the refractory material, but also hinders the steelmaking operation and adversely affects the quality of the steel material. Therefore, there is an urgent need to develop a nozzle for continuous casting of steel that has both blockage resistance and erosion resistance.

In such a situation, Japanese Patent Laid-Open Publication No.
The 3258 JP, a) Al containing ₂ O ₃ 90 wt% or more; b) containing MgO 90 wt% or more; c) 1 or the respective material containing ZrO ₂ 90 wt% or more as a cylindrical sleeve or Disclosed is a nozzle used by interpolation in combination of two or more types.

In order to reduce the clogging of the nozzle, the inner body of the immersion nozzle has a carbon or SiO ₂ content of less than 1% by weight, a spinel of 1 to 40% by weight, M
Japanese Patent Application Laid-Open No. Hei 5-237610 proposes to use a refractory material having a gO of 0.5 to 15% by weight and a balance of Al ₂ O ₃ .

[0005]

The major mechanism of Al ₂ O ₃ -SiO ₂ -C quality nozzle blockage in the casting of Al-killed steel INVENTION SUMMARY is], it is considered as follows. First, in a refractory at a high temperature, S used as a refractory raw material
The reaction of formula (1) occurs between iO ₂ and C. And
Generated SiO [gas phase: described below as (g)] and C
O (g) diffuses into the interface between the nozzle and the molten steel, and A in the molten steel
1 reacts with the formulas (2) and (3) to form a mesh-like alumina on the working surface of the nozzle, and is fused to the nozzle surface to be the starting point of the adhesion of Al ₂ O ₃ inclusions. As the adhesion of the Al ₂ O ₃ inclusion proceeds, the nozzle blockage proceeds.

[0006]

Embedded image SiO ₂ (s) + C (s) = SiO (g) + CO (g) (1)

## STR2 ## 3SiO (g) +2 Al = Al 2 O 3 (s) +3 Si (2)

Embedded image 3CO (g) +2 Al = Al ₂ O ₃ (s) +3 C (3) In the above formula, (s) represents a solid phase, and Al , S
i and C represent Al, Si and C in a molten state in molten steel, respectively.

On the other hand, regarding the erosion mechanism of the Al ₂ O ₃ -SiO ₂ -C type nozzle in the casting of high oxygen content steel, high Mn content steel, stainless steel, etc., first, the carbon in the working surface of the refractory material is molten steel. Dissolved in

Embedded image C = C (4) running surface is Al ₂ O ₃ -SiO ₂ -based oxide. afterwards,
Mn , O , and Fe in the molten steel permeate the operating surface in the MnO, FeO state,

Embedded image Mn + O 2 = (MnO) (5)

Embedded image Fe + O = (FeO) (6) Further, MnO—FeO-based inclusions in the molten steel collide with the working surface,
Adhere to. MnO, Fe that has penetrated for these two reasons
O reacts with working surface in _{Al 2 O 3, SiO 2,} Al 2 O
₃ to produce a liquid slag -SiO ₂ -MnO-FeO system. When the slag flows into the molten steel flow, erosion of the refractory material occurs.

However, the conventional nozzle is effective to some extent in suppressing nozzle clogging, but has a problem in suppressing nozzle erosion. There was a problem with the suppression.

Accordingly, it is an object of the present invention to solve the above-mentioned conventional problems and to provide a nozzle for continuous casting of steel which has both resistance to clogging and resistance to erosion.

[0010]

That SUMMARY OF THE INVENTION The continuous casting nozzle of the steel of the present invention, lumen and / or the portion in contact with the molten steel nozzle, Ri Do spinel or spinel and periclase as mineral phase, free Al ₂ O ₃ is absent,
And the content of impurity components other than Al ₂ O ₃ and MgO is 3% by weight.
%, Characterized in that it consists Der Ru refractory material below.

[0011] The nozzle for continuous casting of steel of the present invention comprises:
It is characterized in that the refractory material of the nozzle in contact with the inner hole and / or the molten steel is made using a spinel material.

The nozzle for continuous casting of steel according to the present invention comprises:
The refractory material in the inner hole portion of the nozzle and / or the portion in contact with the molten steel is manufactured using a refractory raw material having a particle size of 1000 μm or less and a particle size ratio of 500 μm or less of 60% by weight or more. And

Further, the nozzle for continuous casting of steel of the present invention comprises:
The thickness of the refractory material at a portion in contact with the inner hole portion and / or the molten steel of the nozzle is 2 to 10 mm.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below.
Continuous casting nozzle of the steel of the present invention, the portion in contact with the lumen and / or the molten steel nozzle, Ri Do spinel or spinel and periclase as mineral phase, free Al ₂
O ₃ is absent and impurities other than Al ₂ O ₃ and MgO
It is characterized in that component content and a Der Ru refractory material 3 wt% or less.

The refractory material of the present invention comprises carbon and SiO
Since No. ₂ is not used, when it is used for casting Al-killed steel, the reactions of formulas (1) to (3) do not occur, and a mesh-like Al ₂ O ₃ layer does not occur on the operating surface of the refractory material. As a result, adhesion of the Al ₂ O ₃ inclusions to the operating surface and clogging of the nozzle due to the adhesion of the inclusions are significantly suppressed.

Further, the refractory material of the present invention is a mineral phase comprising spinel or spinel and periclase,
Since free Al ₂ O ₃ is not contained, high oxygen content steel,
When used for casting of high Mn-containing steel or stainless steel, erosion of the refractory material is also suppressed.

The detailed basis can be considered as follows, based on the test results described in the following examples: Al ₂ O ₃ is a composite oxide (spinel) with MgO; Since the thermodynamic activity of Al ₂ O ₃ decreases, penetration of MnO and FeO from molten steel becomes difficult; ・ Reactivity between periclase and molten steel is small, so that MnO and FeO from molten steel hardly penetrate into periclase; The solidus temperature of MgO-spinel refractory material is 2000
Since the temperature is extremely high at a temperature of not less than ° C., a liquid slag phase hardly occurs even if MnO or FeO permeates.

As described above, the feature of the nozzle of the present invention is that the mineral composition of the refractory material used is controlled. That is,
Even with similar chemical components, different constituent minerals (crystal structures) naturally result in different reactivity with molten steel, which in turn causes a large difference in erosion resistance.

In the present invention, the refractory material in the inner hole portion of the nozzle and / or the portion in contact with the molten steel is made of a spinel crystal or a periclase crystal composed of MgO and a spinel crystal which is a composite oxide of Al ₂ O ₃ and MgO. Is what is done. However, when the refractory material of the present invention is produced using a practical refractory raw material, there may be unavoidable impurity minerals accompanying unavoidable impurity components. It is preferable to suppress inevitable impurity minerals as much as possible, and therefore, Al ₂ for constituting spinel and periclase is preferably used.
The content of impurities other than O ₃ and MgO is preferably 3% by weight or less. If the content exceeds 3% by weight, the erosion resistance of the impure mineral portion accompanying the impure component is low, so that the impure mineral portion is eroded prior to spinel or periclase, which is not preferable. It is more preferably at most 1% by weight.

The refractory material used in the nozzle of the present invention may be applied to the inner hole of a continuous casting nozzle such as a long nozzle and a submerged nozzle and / or a portion in contact with molten steel.
Regarding the method of manufacturing the nozzle, the raw material blend of the refractory material of the present invention constituting the inner hole portion of the nozzle and / or the portion in contact with the molten steel and the raw material blend of the refractory material constituting the nozzle body are simultaneously pressure-formed. A method of forming into a predetermined nozzle shape (simultaneous forming method), or kneading a refractory raw material for forming a refractory material of the present invention constituting a portion in contact with an inner hole and / or molten steel in a preformed nozzle body. After the formed composition is cast or press-molded, it may be dried, baked if necessary, and manufactured (interior method). Further, Al ₂ O ₃ -C refractory materials and Al ₂ O ₃ -SiO ₂ -C which are conventionally used as refractories constituting the nozzle body are used.
A high quality refractory material or the like can be used as appropriate.

FIGS. 1 to 5 show examples of distribution patterns of the refractory material in the nozzle of the present invention. Here, FIGS.
The ZrO ₂ -C type refractory material (3) is disposed on the powder line portion of the immersion nozzle. The powder line part
This zone is in contact with the highly erodible mold powder during use of the immersion nozzle.
₂ O ₃ —SiO ₂ —C based refractory material (2) is made of Z having excellent corrosion resistance.
The powder line portion is reinforced with an rO ₂ -C refractory material (3). Note that Al ₂ O ₃ —Si
O ₂ -C system and ZrO ₂ one C-based refractory material can be used as conventional compositions. In the Al ₂ O ₃ -SiO ₂ -C refractory material, e.g., Al ₂ O _3: 30~90 wt%, SiO _2: 0 to 35 wt%, C: 10 to 35 wt%
Can be used, and Zr
In the case of an O ₂ -C refractory material, for example, CaO-stabilized Z
When rO ₂ is used, ZrO ₂ : 66 to 88% by weight, C
Those having a composition of aO: 2 to 4% by weight and C: 10 to 30% by weight can be used. As the ZrO ₂ raw material, CaO-stabilized ZrO ₂ is generally widely used. In addition, MgO-stabilized ZrO ₂ , Y ₂ O ₃ -stabilized ZrO ₂ , and baddelite can be used. In addition, in FIGS. 1 to 5, (1) is a refractory material whose mineral phase is composed of spinel or spinel and periclase, that is, the refractory material of the present invention. Also, it should be understood that the material distribution pattern of the nozzle of the present invention is not limited to those shown in FIGS.

In the case of simultaneous molding, Al ₂ O ₃ —S kneaded with a phenol resin or polysaccharide as a binder is used.
A raw material composition of the refractory material constituting the nozzle body such as an iO ₂ -C refractory material and a raw material composition of the refractory material of the present invention constituting a portion in contact with the inner hole and / or the molten steel are put into a predetermined form , Filled with CIP etc., dried,
It can be manufactured as an unfired product or fired. The refractory material constituting the nozzle body and the refractory material of the present invention constituting the portion contacting the inner hole and / or the molten steel are preferably kneaded with the same kind of binder.

In the case of the interior method, a binder similar to the nozzle body or a binder such as silicate or phosphate is used for the nozzle body previously prepared by a conventional method.
It can be produced by casting or press-molding the kneaded raw material mixture, followed by drying and, in some cases, firing.

However, the method of inserting and loading the separately prepared interior part (the part in contact with the inner hole and / or the molten steel) by pressure molding, pouring or press-fitting molding into a nozzle body previously prepared by a conventional method is not used. This is not preferable because of poor compatibility with the refractory material constituting the nozzle body (adhesion stability). In particular, the refractory material constituting the portion in contact with the lumen and / or the molten steel of the present invention, since the spinel or spinel and periclase, the nozzle body Al ₂ O ₃ -C based or Al ₂ O ₃ -SiO ₂ - The above-mentioned simultaneous molding method or interior method is preferred in order to have a larger expansion property than the C-based refractory material and to stably maintain the adhesiveness when heated to a high temperature during use.

Similarly, the refractory material of the nozzle body and the refractory material constituting the portion that comes into contact with the inner hole and / or the molten steel are better kneaded with the same kind of binder as described above, and the adhesion is stabilized. Can be.

On the other hand, in producing the refractory material of the present invention, it is desirable to use a spinel material or a magnesia material comprising a spinel material and periclase as a starting material. When a magnesia raw material and an alumina raw material are used at the same time as starting materials, magnesia and alumina react with each other to generate spinel during firing or use of the refractory material, but as the reaction progresses, the refractory material expands and cracks There is fear. It should be noted that the spinel raw material does not necessarily have a theoretical composition of MgO: Al ₂ O ₃ constituting the spinel, but contains MgO in excess of spinel and periclase or Al ₂ O _{3 in} excess as free alumina. Those without corundum crystals can be used. The spinel raw material and the magnesia raw material can be used irrespective of whether they are electrofused products or fired products.

The starting material formulation for forming the refractory material of the present invention has a particle size of 1000 μm or less and 500 μm or less.
The particle size ratio of m or less is preferably 60% by weight or more. If particles exceeding 1000 μm are present, the particle size of the raw material is too large with respect to the nozzle thickness, which may cause embrittlement of the refractory structure and dropout of particles during use. Also, 500 μm
When the following particle size ratio is less than 60% by weight, in particular, when performing simultaneous molding, the moldability is inferior and a satisfactory molded body is often not obtained. The raw material having a particle size of less than 0.5 μm is 20
Exceeding the weight percent deteriorates the spall resistance of the refractory material,
Undesirably, cracks occur.

Further, when the refractory material of the present invention is applied to the inner hole of the nozzle and / or the portion in contact with the molten steel, its thickness is preferably in the range of 2 to 10 mm. When the thickness of the refractory material is less than 2 mm, its strength is small, so that it cannot withstand the impact of the molten steel flow and may fall off from the nozzle body.
On the other hand, if it exceeds 10 mm, the thermal expansion difference between the nozzle body and the refractory material constituting the nozzle body is large, so that cracks due to the thermal expansion may occur (spoil resistance deteriorates), which is not desirable.

[0029]

EXAMPLES Tests for spall resistance, adhesion resistance to Al ₂ O ₃ inclusions, and erosion resistance of each of the samples of the present invention and the comparative product will be described below. The evaluation test for spall resistance
Melt 200 kg of steel in a high frequency furnace and pre-
A sample having dimensions of 40 × 40 × 230 mm preheated for 5 hours was immersed in molten steel at 1580 ° C. for 5 minutes, and then pulled up.
Cooled in air. After cooling, the sample was evaluated for the occurrence of cracks. Ten samples were prepared and evaluated by the number of samples having cracks. The evaluation test of the erosion resistance was performed on a high oxygen content steel at 1580 ° C. in an argon atmosphere with a diameter of 40 m.
m, a sample with a height of 230 mm is immersed, and 100 rpm
After rotating at a speed of 60 minutes for 60 minutes, the sample was evaluated for the amount of decrease in diameter. The evaluation test of the adhesion resistance to Al ₂ O ₃ inclusions was performed by immersing a sample having a diameter of 40 mm and a height of 230 mm in Al-killed steel at 1580 ° C. in an argon atmosphere,
The evaluation was made based on the thickness of the Al ₂ O ₃ adhesion layer on the sample operating surface after rotating at 60 rpm for 60 minutes.

Example 1 To a mixture of starting materials shown in Table 1 below, 2% by weight of a phenol resin was added as a binder and kneaded.
CIP molding was performed at 00 kgf / cm ² , followed by drying at 250 ° C. for 3 hours to prepare a sample. In this embodiment,
As a spinel material, the weight ratio of MgO: Al ₂ O ₃ is 2
A spinel material close to the theoretical composition of 8:72 and Mg
A magnesia-excess spinel raw material having a weight ratio of O: Al ₂ O ₃ of 50:50 was used. The obtained sample was subjected to the spall resistance test, the erosion resistance test, and the Al ₂ O ₃ resistance test as described above.
An adhesion test was performed. Table 1 also shows the obtained results.

[0031]

[Table 1]

In Table 1, the symbols in the mineral phase column of the sample represent P: periclase, S: spinel, C: corundum, and M: mullite. From the results in Table 1, it can be seen that: The spall resistance is poor in Comparative Example 1 containing 100% by weight of MgO and 78% by weight of MgO, 22% by weight of Al ₂ O ₃ and Comparative Example _{3 having} a mineral phase of periclase and corundum. However, the other samples had no problem; the erosion resistance was the worst in Comparative Example 4 (conventional Al ₂ O ₃
-SiO ₂ -C-based refractory material), then Comparative product 2 and Comparative product 3, but there was no problem other than that; Comparative product 4 had poor adhesion to Al ₂ O ₃ inclusions,
In other samples, no Al ₂ O ₃ adhesion layer was observed. Therefore, in the nozzle of the present invention, the inner hole of the nozzle and / or
Alternatively, it was found that the refractory material provided in the portion in contact with the molten steel had both spall resistance, erosion resistance, and Al ₂ O ₃ inclusion adhesion.

Example 2 Example 1 was prepared using the starting material formulations shown in Table 2 below.
Samples were prepared in the same manner as described above, and evaluation tests for spall resistance, erosion resistance, and Al ₂ O ₃ inclusion adhesion were performed.
The obtained results are also shown in Table 2.

[0034]

[Table 2]

From the results in Table 2, it can be seen that: when the maximum particle size of the starting material exceeds 1000 μm, coarse particles on the sample surface fall off; when the proportion of the starting material less than 0.5 μm is less than 20% by weight, If it is present, it does not significantly affect the spall resistance, but 20% by weight.
When the ratio exceeds 300, the spall resistance is remarkably reduced; the influence of the particle size is small on the erosion resistance and the Al ₂ O ₃ inclusion adhesion.

Example 3 Al ₂ O ₃ —SiO ₂ —C of Comparative Example 4 shown in Table 1 above
The present invention 1 shown in Table 1
(Nozzle outer diameter 130m
m, inner diameter 70 mm, length 600 mm) by changing the thickness of the inner hole member material (1 mm, 2 mm, 5 mm, 8 mm, 10 mm)
mm, 12 mm: However, the body thickness of the nozzle is constant). The sample was obtained by simultaneous molding by CIP molding, standing for 24 hours, and further drying at 105 ° C. for 24 hours. The distribution pattern is as shown in FIG.
With respect to the test sample of the obtained nozzle, the spall resistance of each sample was compared based on the presence or absence of cracks when immersed for 1 hour in 200 kg of molten steel melted at 1580 ° C. in a high frequency furnace. Ten samples were prepared, and the spall resistance was evaluated based on the number of samples having cracks. Table 3 shows the test results.

[0037]

[Table 3]

As shown in Table 3, when the thickness of the inner hole is less than 2 mm, the interior part may fall off.
It was found that the spall resistance remarkably decreased when the thickness exceeded mm.

Example 4 In order to evaluate the effect of the nozzle of the present invention, an actual machine test was performed. Al ₂ O ₃ − of the immersion nozzle of the product 13 of the present invention shown in Table 3 and the comparative product 4 of Table 1 having the distribution pattern shown in FIG.
SiO ₂ -C refractory materials and ZrO ₂ -C refractory materials (Ca
A nozzle of a comparative product of a conventional product in which O-stabilized ZrO _{2 (} 80% by weight and graphite 20% by weight) was combined was tested. The test was conducted on a low carbon Al-killed steel (composition = C: 0.08% by weight, S
i: 0.03% by weight, Mn: 0.2% by weight, P: 0.01
% By weight, S: 0.01% by weight, Al: 0.05% by weight,
O: 10 ppm) at a casting temperature of 1580 ° C. The thickness of the maximum Al ₂ O ₃ inclusion layer of the inner tube after casting for 250 minutes is 15 mm for the comparative nozzle, but only 3 mm for the nozzle of the present invention, and the significant Al _The effect of reducing the adhesion of ₂ O ₃ was observed. In addition, there was no cracking or falling off of the nozzle inner hole, and the operation was safe.

Example 5 The same two immersion nozzles as in Example 4 were connected to a high oxygen content steel (composition = C: 30 ppm, Si: 20 ppm, Mn: 0.3).
% By weight, P: 0.01% by weight, S: 0.01% by weight, A
(1:10 ppm, O: 600 ppm). As a result of the test, the maximum damage thickness of the inner tube after casting for 230 minutes was 11 mm for the comparative nozzle.
In contrast, the nozzle of the present invention is only 1 m
m, and damage to the immersion nozzle was significantly reduced. Also,
Even in this case, there was no cracking or falling off of the inner hole of the nozzle, and safe operation was possible.

Example 6 The same two immersion nozzles as in Example 4 were connected to a high Mn-containing steel (composition = C: 0.04% by weight, Si: 0.02% by weight, Mn:
(1.5 wt%, P: 0.01 wt%, S: 0.01 wt%, O: 100 ppm). As a result of the test, the maximum damage thickness of the inner pipe after casting for 210 minutes was 13 mm for the comparative nozzle, but only 1.5 mm for the nozzle of the present invention, and the damage of the immersion nozzle was remarkable. It has become smaller. There was no cracking or falling off of the nozzle inner hole.

Example 7 The same two immersion nozzles as in Example 4 were connected to stainless steel (composition = C: 0.05% by weight, Si: 0.5% by weight, Mn:
1.0% by weight, P: 0.04% by weight, S: 0.02% by weight, Ni: 8.0% by weight, Cr: 18.0% by weight, O: 5
(0 ppm) continuous casting. As a result of the test, the maximum damage thickness of the inner pipe after casting for 260 minutes was 9 mm for the comparative product nozzle, whereas it was 0.5 mm for the nozzle of the present invention. Reduced. Also in this case, there was no cracking or falling off of the nozzle inner hole.

Example 8 The same two immersion nozzles as in Example 4 were connected to Ca-treated steel (composition = C: 0.05% by weight, Si: 0.3% by weight, Mn: 0.3% by weight).
8% by weight, P: 0.01% by weight, S: 0.01% by weight, A
l: 0.02% by weight, Ca: 30 ppm, O: 20 pp
m) was used for the continuous casting. As a result of the test, the maximum damage thickness of the inner tube after casting for 200 minutes was 1 mm in the nozzle of the present invention, while the nozzle of the comparative product was 8 mm, and the damage of the immersion nozzle was significantly reduced. . In addition, there was no crack or falling off of the nozzle inner hole.

[0044]

By using the nozzle of the present invention, clogging of the nozzle due to adhesion of Al ₂ O ₃ inclusions during casting of Al-killed steel is greatly suppressed.
In the case of casting of high Mn-containing steel, stainless steel or Ca-treated steel, damage to the nozzle was significantly reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a material distribution pattern of a nozzle according to the present invention.

FIG. 2 is a view showing another embodiment of the material distribution pattern of the nozzle of the present invention.

FIG. 3 is a view showing another embodiment of the material distribution pattern of the nozzle of the present invention.

FIG. 4 is a view showing another embodiment of the material distribution pattern of the nozzle of the present invention.

FIG. 5 is a view showing another embodiment of the material distribution pattern of the nozzle of the present invention.

FIG. 6 is a diagram showing a material distribution pattern of a conventional nozzle.

[Explanation of symbols]

Refractory material of the 1 invention ₂ Al 2 O ₃ -SiO 2 -C refractory material 3 ZrO ₂ one C-based refractory material

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-5-285612 (JP, A) JP-A-5-237610 (JP, A) JP-A-61-2232266 (JP, A) JP-A-61-216 172569 (JP, A) JP-A-8-67558 (JP, A) JP-A-7-116795 (JP, A) JP-A-9-220652 (JP, A) JP-A-9-220650 (JP, A) JP-A-9-220648 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B22D 11/10 330 B22D 41/54 C04B 35/10

Claims (4)

(57) [Claims] 1. A nozzle for continuous casting of steel, lumen and / or the portion in contact with the molten steel nozzle, Ri Do spinel or spinel and periclase as mineral phase,
Free Al ₂ O ₃ is absent, and Al ₂ O ₃ and MgO
Nozzle for continuous casting of steel, characterized in that the impurity components content than is composed der Ru refractory material 3 wt% or less. 2. The nozzle for continuous casting of steel according to claim 1, wherein the refractory material is produced using a spinel raw material. 3. The steel according to claim 1, wherein the refractory material is produced using a refractory raw material having a particle size of 1000 μm or less and a particle size ratio of 500 μm or less of 60% by weight or more. Nozzle for continuous casting. 4. The nozzle for continuous casting of steel according to claim 1, wherein the refractory material is disposed at a thickness of 2 to 10 mm at an inner hole of the nozzle and / or at a portion in contact with molten steel. .