JPS5953143B2 - Continuous casting mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a continuous casting mold, and an object of the present invention is to provide a durable continuous casting mold that prevents cracks that are likely to occur in the upper part of the mold. .

Molds for continuous casting (hereinafter referred to as molds) include assembly molds for large castings and tube molds for small castings, but due to their characteristics, they are made of metal with good thermal conductivity, and they are made of metal with good thermal conductivity. The structure is such that the heat is cooled through the metal walls.

That is, since the mold material must be a metal with good thermal conductivity, copper is generally used in most cases.

However, a mold made of steel has the disadvantage that the inner wall is scraped when molten steel passes through it, and the steel penetrates into the surface of the cast steel ingot, significantly degrading the quality of the steel ingot.

Various inventions have been made in the past as countermeasures against this problem.

The main one is to protect the inner surface of the mold with other metals.

For example, Japanese Patent Publication No. 46-37266 discloses coating the inner surface of the mold, that is, the surface in contact with molten steel, with molybutin and zirconium oxide.

Further, Japanese Patent Publication No. 48-28255 discloses applying nickel plating to the inner surface of the mold.

Further, Japanese Patent Laid-Open No. 49-83620 proposes to use nickel, chromium, molytein, or stainless steel for the inner surface of the mold.

However, among these known examples, those using molybdenum can only be lined by plating or thermal spraying, so the metallurgical bond with the mold is weak, and zirconium oxide can only be lined by thermal spraying. Since it cannot be soaked, it also has a weak metallurgical bond similar to the above-mentioned molybdenum, and both have problems with durability.

Further, in the case of stainless steel, since its thermal conductivity is low, it inhibits the thermal conductivity required of the molding material, which is undesirable.

As for chromium, plating is the only way to form a layer on the inside of the mold, and the plating thickness is only 0.3 mm.
Since it can only do the following, there is a problem with durability.

Therefore, nickel is currently used in large quantities, and methods for coating the inner surface of the mold include explosive crimping, plating, and thermal spraying.

However, molds coated with nickel on the inside tend to crack at the top during use.

The present invention has been made with the aim of improving the above-mentioned drawbacks of conventional molds, and is made by adding at least one of Ti, Zr, Nb, Ta, or Be or V to Ni or a Ni-based alloy. A mold for continuous casting characterized by being lined with a Ni alloy containing at least one of these in the range of 0.1 to 2.5%, which impairs the thermal conductivity of the mold. The inner wall is not scraped by molten steel, and the upper part does not crack, improving durability.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

The mold is constructed with a metal wall 1 with cooling fluid passages 7.

The metal wall 1 is made of a metal material with good thermal conductivity, and a lining 2 made of a metal material with good wear resistance is applied inside the metal wall 1, and the two are metallurgically bonded.

3 is a meniscus formed above the molten metal when it is poured into the mold.

4 is the molten metal, and 5 is its solidified portion. Conventionally, when Ni was used for the part 2, cracks were likely to occur in the upper part 6 of the mold, which was the part where the meniscus 3 was in contact.

Instead of this, Ti, Zr,
At least one of Nb and Ta or at least one of Be and V in an amount of 0.1 to 2.5
It has been found that cracks do not occur when using a Ni alloy containing Ni within a range of 1.5%.

In this case, if the proportion of trace elements added to Ni or Ni-based alloy is too small, it will be meaningless, and as the quantity increases, the thermal conductivity will deteriorate, resulting in a cost disadvantage, so it should be 0.1 to 2. A range of .5% is preferred.

However, since the methods of using molds and the properties of molten steel vary, it is necessary to take these conditions into consideration, change the amount of trace additive elements little by little, and carefully combine them.

Moreover, if the entire mold is made using such Ni alloy,
Thermal conductivity decreases and it is disadvantageous in terms of cost, so
It is advantageous to press the sheet inside a conventional copper material to form a mold.

Among the additive elements, Ti, Zr, Nb, and Ta are impurities in Ni or Ni-based alloys (for example, C5S, etc.)
It has the effect of fixing the crystal grains and improving physical properties by making the crystal grains smaller.

Any element may be used, but in terms of cost, thermal conductivity, physical properties, etc., it is more advantageous to use an element with a small atomic number.

In addition, Be and ■ tend to increase corrosion resistance in the atmosphere under the conditions of use as a mold, while Ti and Zr.

It is even more effective when used together with Nb and Ta.

Although the present invention may be applied to the entire mold, since the purpose is to prevent the occurrence of cracks in the part of the inner wall 6 that the meniscus 3 contacts, it is applied only to this part,
The lower portion of the inner wall may be lined with another metal such as Ni.

Furthermore, as a method for forming the lining in the present invention, an explosive crimping method is often used, but a build-up method, a rolling method, etc. may also be used.

Example 1 Copper plate 2 with a thickness of 60 mm, a width of 750 mm, and a length of 860 mm
Ni alloy plate (6X 780X
880) were explosively bonded one by one to create two short sides for assembly molds.

This was combined with a normal Ni coating mold (two long sides) to create an assembly mold.

As a result of continuous casting of copper plate steel using this mold, 3
At 0.00 charge, cracks occurred in the Ni-coated mold, but no cracks occurred in any of the molds according to the present invention.

Example 2 In the same manner as in Example 1, a metal plate mold having the composition shown in Table 2 was attached to the short side inner surface and tested. As a result, the Ni-coated mold cracked at 300 charges, whereas the present invention No cracks occurred in the mold.

[Brief explanation of drawings]

The figure is a sectional view showing the mode of use of the mold of the present invention. 1...Metal wall, 2...Inner lining, 3...
・・・Meniscus, 4... Molten metal, 5...
... Solidified part, 6 ... Upper part of mold inner wall,
7... Cooling fluid passage.

Claims (1)

[Claims] l Ni or Ni-based alloy D Ti, Zr, Nb,
1. A mold for continuous casting, characterized in that the mold is lined with a Ni alloy containing at least one of Ta in a range of 0.1 to 2.5%. 2 Ni or Ni-based alloy with Ti, Zr, Nb,
Ni contains at least one of Ta and at least one of Be and V in the range of 0.1 to 2.5%.
A continuous casting mold characterized by an alloy lining.