JPS6026070B2 - Immersion nozzle for continuous casting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a continuous casting nozzle with improved corrosion resistance against slag powder.

Generally, continuous casting nozzles are used to pour molten metal from a container such as a tundish into a casting mold without oxidizing it. It is immersed in the molten metal, and is in contact with slag powder (mainly composed of calcium fluoride, silicon oxide, aluminum oxide, alkaline substances, etc.) for preventing oxidation floating on the top surface of the molten metal.

As a result, the contact portion was severely eroded mainly by the slag powder, causing local damage, resulting in a significant reduction in the durability of the nozzle. For this reason, alumina-graphite type nozzles are used as the immersion nozzle for continuous casting, but they are different from those for the slag powder mentioned above. However, the corrosion resistance of the slag powder is not always sufficient, and the parts that come into contact with the slag powder are now fused and cannot be used for a long period of time.

The present invention was made to eliminate the above-mentioned drawbacks, and has excellent corrosion resistance against molten metal, molten metal slag, and slag powder that coexists with these, and at the same time has good spalling resistance. It is intended to provide a cellulose nozzle.

That is, the continuous casting nozzle of the present invention is composed of 45 to 65% zircon, 10 to 40% graphite, 1 to 15% fused silica, and 1 to 10% metal silicon in weight proportions. The immersion nozzle for continuous casting of the present invention has excellent corrosion resistance against molten metal, molten metal slag, and slag powder, which is a feature of zircon, and has improved thermal shock resistance, which is a feature of graphite, and the nozzle itself. Has a weight saving effect.

In addition, it has the effect of improving spalling resistance, which is a feature of fused silica, and also has the effect of acting as a carbonaceous binder, which is a feature of the metal silicon blended, and the effect of making it difficult to wet with molten metal slag. The present invention will be described in detail below, and all percentages in the description are by weight.

First, 45 to 65% zircon powder, 10 to 40% graphite powder, 1 to 15% fused silica powder, and 1 to 10% metal silicon powder are mixed to prepare a raw material powder. Add a primary binder such as methylcellulose or phenol resin and thoroughly knead.

Next, this mixture is either as it is or granulated to an appropriate particle size, filled in an isostatic press machine and pressure-molded, and then the molded product is fired at a temperature of 850°C to produce a material for continuous casting. Obtain an immersion nozzle. The reason why the amount of zircon in the immersion nozzle of the present invention is limited to the above range is that if the amount of zircon is less than 45%, the corrosion resistance cannot be sufficiently exhibited, whereas if the amount exceeds 65%, the corrosion resistance is This is because although the spalling resistance is improved, the spalling resistance is significantly reduced.

In addition, the reason why the amount of graphite blended in the immersion nozzle was limited to the above range is that if the amount of graphite is less than 10%, the effect of improving thermal shock resistance and properties cannot be expected;
This is because if it exceeds this, corrosion resistance will be impaired.

Furthermore, the reason why the amount of fused silica in the immersion nozzle was limited to the above range is that if the amount of silica is less than 1%, no improvement in spalling resistance can be expected; This is because, if it exceeds this, although spalling resistance improves, corrosion resistance significantly decreases.

Furthermore, the reason why the amount of metal silicon in the immersion nozzle is limited to the above range is that the amount of metal silicon is 1%.
If the amount is less than 10%, the binding effect on graphite during heating will be impaired, resulting in a decrease in oxidation resistance, and "dripping" with molten metal or molten metal slag will increase during casting, while the amount exceeds 10%. This is because it impairs corrosion resistance.

Next, examples of the present invention will be described.

0.8 parts by weight of the raw material powder having the composition ratio of Example 1, and 0.8 parts by weight of the surfactant.
After adding and mixing 0.5 parts by weight of lignin and molding with an isostatic press (pressure 1000k9/lump), this molded body was fired for one hour at a temperature of 850q○ to form an immersion groove for continuous casting. Got the nozzle.

This dipping nozzle for continuous casting had an apparent specific gravity of 3.20, a bulk specific gravity of 2.53, and a porosity of 21.0%. A counterfeit nozzle for continuous casting was obtained in the same manner as in Example 1, except that raw material powder having the composition ratio of Comparative Example was used.

This immersion nozzle has an apparent specific gravity of 2.97 and a high specific gravity of 2.43.
The porosity was 18.4%. However, the above Example 1
The immersion nozzle of the comparative example is connected to a tundish with a capacity of 25mbn, and the lower end is immersed in the molten metal in the casting mold, and one charge is defined as casting the entire amount of molten metal in the tundish, and how many charges? It was visually inspected to see if the outer diameter of the nozzle that came into contact with the slag powder on the upper surface of the mold was immersed and became unusable.

As a result, the continuous casting nozzle of the present invention (Example 1)
could be used for more than 5 to 6 charges without noticeable erosion of the outer diameter. On the other hand, the conventional immersion nozzle (comparative example) has 2 to 3
After charging, the outer diameter became severely stained and became unusable. 0.8 parts by weight of surfactant and 8 parts by weight of liquid phenol resin were added to log parts by weight of raw powder having the composition ratio of Example 2, and after molding with an isostatic press (pressure 1000k9/base), The molded body was fired at a temperature of 850° C. for 10 hours to obtain an immersion nozzle for continuous casting.

The obtained immersion nozzle has a specific gravity of 8.27 and a high specific gravity of 2.27.
61, and the porosity was 20.4%.

In addition, the above-mentioned erosion nozzle was installed in a tundish having a capacity of 25 skins as in Example 1, and it was investigated at what number of charges the outer diameter of the nozzle part that comes into contact with the slag powder becomes eroded and becomes unusable.

Claims (1)

[Claims] 1 Weight percentage: 45-65% zircon, 10-10% graphite
40%, fused silica 1-15%, and metallic silicon 1
Immersion nozzle for continuous casting consisting of ~10%.