JP2971230B2 - Horizontal continuous casting method of slab strand for wire rod - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method of directly manufacturing a product such as a welding material using a molten metal of an Fe-based, Ni-based, or Co-based alloy, and a material for various wire products (hereinafter referred to as a wire casting material). (Referred to as a single strand).

[0002]

2. Description of the Related Art A function for allowing a molten metal contained in a molten metal holding furnace such as a tundish or the like to constitute a horizontal continuous casting machine to flow smoothly into a horizontally arranged casting mold into a side wall nozzle portion of the container. Is installed.

[0003] The break ring is liable to cause deterioration of the material due to wetness and chemical reaction due to contact with the molten metal.
Since the tensile stress and the compressive stress are repeatedly applied with the drawing of the slab strand, the wear due to this is remarkable. For this reason, in this type of continuous casting, a break ring made of a nitride-based or ZnO ₂ -based material centering on BN is generally used.

[0004]

By the way, when a continuous caster equipped with a break ring made of the above material is used to cast a molten metal such as an Fe-based, Ni-based or Co-based alloy, Particularly, the material deterioration and wear of the break ring are particularly remarkable, and as a result, the drawing resistance increases, and there is a problem that the slab strand during the drawing movement breaks from its weakest portion, and the break ring has a length of more than 2 hours. Continuous casting over time was not possible.

An object of the present invention is to stably cast a slab strand for a long time even in horizontal continuous casting using a molten metal such as an Fe-based, Ni-based or Co-based alloy, which is liable to cause early deterioration of break rings. It proposes a new method that can be pulled out.

[0006]

SUMMARY OF THE INVENTION The present invention relates to an Fe-based, Ni-based
In a horizontal continuous casting method of casting a slab strand for a wire using a molten metal of a base or Co-based alloy, each of O and S contained in the molten metal is reduced to 50 ppm or less in advance, and the molten metal is Flexural strength at normal temperature of 2000-3000 kgf / mm ² , leading to casting mold, apparent porosity
A wire casting characterized in that the wire is cast from the casting mold while being cooled and solidified through a break ring made of a sintered body of MgO-stabilized ZrO ₂ having a structure stabilization rate of 0.5 to 1.5% and a structure stabilization rate of 20 to 25%. This is a horizontal continuous casting method for one strand.

[0007] In the present invention, as a molten metal of the above-mentioned Fe-based alloy, a component containing 40% or more of Fe as a main component, and a component containing one or more of Cr, Ni, Mo, Al, Cu and Si as alloy components. Those that result in a composition are advantageously suited. Also, Ni
The molten alloy of the base alloy has a composition of 40% or more of Ni as a main component, and other alloy components such as Cr, Fe, Mo, Al, Cu, and Si alone or in combination.
As the molten alloy, those containing 40% or more of Co as a main component and Cr, Ni, Fe, W, Al, Cu, Si, and the like alone or in combination as an alloy component are advantageously suitable.

[0008]

The operation will be described below in detail with reference to the drawings. FIG.
Is an example of a casting machine suitable for horizontal continuous casting of slab strands for wire rods.
Reference numeral 2 denotes a container such as a holding furnace for holding and holding the molten metal 1. The container 2 has a lid 2a, and is shown as an example in which a heating means (heating coil) 2b is buried in its main body. Reference numeral 3 denotes a nozzle portion opened on the side wall of the container 2, 4 denotes a break ring adapted to the nozzle portion 3, 5 denotes a casting mold connected at one end of the break ring 4, and 6 denotes a slab strand C from the casting mold 5. This pinch roll 6 has a push-back mechanism that can push the slab strand C back toward the break ring 5. Reference numeral 7 denotes a winder for continuously winding the slab strand C drawn by the pinch roll 6.

To cast a slab strand C for a wire rod using the casting machine having the above-described configuration, the molten metal transferred from the melting furnace is stored in the container 2 or the raw material is directly charged into the container 2. After being melted by the heating means 2 a, the molten metal 1 is passed through a break ring 4 adapted to the nozzle portion 3.
Into the casting mold 5. The molten metal 1 starts to solidify in the break ring 4, and thereafter is continuously cooled and solidified, pulled out of the casting mold 5 by the pinch roll 6, and sequentially wound up by the winder 7.

In the continuous casting according to such a procedure, in order to smoothly and continuously pull the slab strand C from the casting mold 5, the strand C is once pushed back toward the break ring 4 during the drawing movement of the slab strand. ,
Next, pulling out (one drawing distance e; see FIG. 2) is performed intermittently. At this time, in the break ring 4, tensile stress and compressive stress are caused by the reciprocating motion of the solidified shell being formed here. Are repeatedly added, and in combination with wetness due to contact with a high-temperature molten metal and material deterioration due to a chemical reaction, minute cracks and particle peeling (a) as shown in FIG. Wear is promoted over the circumference, and the initial shape cannot be maintained.

Such wear of the break ring 4 causes a solidified shell to be formed which is larger than the inner diameter of the casting mold 5 connected to the break ring 4 and increases the pull-out resistance of the slab strand C due to the anchor effect. , It broke at its weakest point (see symbol b in FIG. 2), and the casting operation had to be stopped. This is based on the use of Fe-based, Ni-based, and Co-based alloys as molten metal. It was especially noticeable in some cases.

According to the present invention, in horizontal continuous casting using molten Fe-based, Ni-based, and Co-based alloys, O and S contained in these molten metals are reduced to 50 ppm or less in any case and used for casting. As a break ring, the bending strength at room temperature is 2000-3000 kgf / mm ² , and the apparent porosity is
The intended purpose has been advantageously achieved by using a sintered body of a MgO partially stabilized ZrO ₂ material having 0.5 to 1.5% and a microstructure stabilization rate of 20 to 25%.

In the present invention, the reasons for limiting each of O and S in the molten metal to 50 ppm or less are as follows. Any of these elements lowers the interfacial tension of the molten metal and promotes the wetting of the molten metal into the break ring. That is, due to the presence of these elements, Si, Ca, etc. penetrate into the surface layer of the break ring through pores, and particularly in the ZrO ₂ type break ring, MgO in ZrO ₂ is reacted with MgO as a stabilizer. And the deterioration of the material is caused and promoted by the crystal transformation of ZrO ₂ and the accompanying volume change. Such a situation is particularly caused by O and S in the molten metal.
Are remarkable when both exceed 50 ppm. Therefore, in the present invention, both O and S contained in the molten metal are limited to 50 ppm or less.

In order to reduce O and S in the molten metal, raw materials having low O and S may be selected and used in advance, or desulfurization and deoxidation may be applied.

Here, in the horizontal continuous casting of strands for wire rods, since the melting of the raw material is a relatively small volume of the order of 1 ton, an induction furnace is generally used in many cases, and a positive refining reaction takes place. Have difficulty. Therefore, the selection and use of the raw materials as described above are particularly effective.

When desulfurization and deoxidation treatments are applied, it is preferable to carry out them in the following manner.
Since desulfurization proceeds under the conditions of high temperature, high basic slag and low oxygen activity, deoxidation is promoted and high basic slag is added to the molten metal bath surface. For deoxidation, the furnace wall is made of a neutral or basic refractory material, and a forced deoxidizer such as Al is added, and the harmfulness of the product Al ₂ O ₃ is removed. And reforming by combined use of Ca deoxidation, and degassing of the furnace atmosphere by an inert gas such as Ar gas.

Next, according to the present invention, the partially stabilized Zr
O ₂ as break rings for horizontal continuous casting comprised of a sintered body of quality, bending strength at room temperature is 2000~3000kgf / mm ^2,
A material having a porosity of 0.5 to 1.5% and a tissue stabilization rate of 20 to 25% was used for the following reason.

Bending strength at normal temperature: 2000 to 3000 kgf / mm
^2, the withdrawal process of the slab strand in continuous casting, break ring tensile repeatedly at high temperature near the solidification temperature of the molten metal stress, although subjected to compressive stresses, under such harsh conditions, the initial shape of the break ring Is required to have a bending strength of at least about 2000 kgf / mm ² . However, with a bending strength exceeding 3000 kgf / mm ² , porosity cannot be obtained unless the porosity approaches 0 as much as possible on the device, and such a break ring becomes unusable because its thermal shock resistance deteriorates. Therefore, in the present invention, the bending strength of the break ring at room temperature is 2000 to 3000 kgf / mm.
Limited to ² .

Porosity: 0.5 to 1.5% If the porosity of the break ring is less than 0.5%, cracks are likely to occur due to thermal shock and it cannot withstand use. On the other hand, if it exceeds 1.5%, the wetness of the molten metal becomes large and the material deteriorates. Is promoted. Therefore, the porosity of the break ring is limited to 0.5 to 1.5%.

Structure stabilization rate: 20 to 25% The structure stabilization rate is limited to 20 to 25% in order to withstand thermal shock and to minimize the volume change due to the crystal transformation of ZrO ₂ .

A break ring satisfying the above requirements is
For example, it can be easily manufactured by sufficiently pulverizing and mixing the powder ZrO ₂ and the MgO raw material, molding, and then finishing the material fired at a sufficiently high temperature and for a long time by machining such as grinding.

[0022]

[Example] MgO partially stabilized Zr having a bending strength at room temperature of 1100 kgf / mm ² , a porosity of 3.5%, and a tissue stabilization rate of 20%
Break ring (A) made of O ₂ sintered body and sintering of MgO partially stabilized ZrO ₂ material with bending strength at room temperature of 2200 kgf / mm ² , porosity of 0.9% and microstructure stabilization of 23% A horizontal continuous caster having a structure as shown in FIG. 1 in which a break ring (B) made of a body is installed is applied, and a molten metal of an alloy as shown in Table 1 is cast into a slab strand for a wire rod having a diameter of 10 mm. In some cases, their casting times were compared. The results are shown in Table 1.

[0023]

[Table 1]

As is clear from Table 1, according to the present invention, even in the horizontal continuous casting for Fe-based, Ni-based, and Co-based alloys in which the material deterioration and wear of the break ring are particularly remarkable, It was confirmed that the time could be extended significantly.

[0025]

As described above, according to the present invention, the amount of casting in one continuous casting is increased. 1) It is possible to obtain a raw material having a sufficient weight to be supplied to a production process. The productivity in the process can be greatly improved. 2) The operating efficiency of horizontal continuous casting, which involves a series of operations such as pre-heating such as furnace preheating, melting, casting, and post-processing after casting, can be significantly improved. 3) Auxiliary materials such as molds constituting a continuous casting machine can be effectively used, and the cost involved can be reduced as much as possible. 4) Effective consumption of raw materials used for continuous casting is possible,
The cost for this can be reduced as much as possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a horizontal continuous casting machine.

FIG. 2 is an explanatory diagram of a casting situation in horizontal continuous casting.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Molten metal 2 Container 3 Side wall nozzle 4 Break ring 5 Casting mold 6 Pinch roll 7 Winding machine C Cast strand

Continuing from the front page (72) Inventor Hiroki Takahashi 4-2 Kojima-cho, Kawasaki-ku, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Nippon Yakin Kogyo Co., Ltd. Research and Development Headquarters R & D Headquarters (72) Inventor Hiroshi Ogihara 4 Kojima-cho, Kawasaki-ku, Kawasaki-ku, Kanagawa Prefecture No. 2 Nippon Yakin Kogyo Co., Ltd. Research and Development Headquarters Technology Research Laboratory (72) Inventor Makoto Anazawa 4-2 Kojimacho, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture Nippon Yakin Kogyo Co., Ltd. Research and Development Headquarters Technology Research Laboratory (56) References Special JP-A-2-263540 (JP, A) JP-A-2-137646 (JP, A) JP-A-63-230261 (JP, A) JP-A-64-56399 (JP, A) JP-A-62-68658 (JP JP, A) JP-A-64-17823 (JP, A) JP-A-62-124264 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B22D 11/04 114

Claims (1)

(57) [Claims] 1. A horizontal continuous casting method for casting a slab strand for a wire rod using a molten metal of an Fe-based, Ni-based or Co-based alloy, wherein each of O and S contained in the molten metal is 50 ppm or less in advance. reduced to, the molten metal, leading to the casting mold, strength 2000 to 3000 kgf / mm ² bending at ordinary temperature, and the apparent porosity of 0.5% to 1.5%, the tissue stabilizing factor is stable 20-25% of MgO portion A horizontal continuous casting method of a strand for a wire rod, wherein the strand is drawn out of the casting mold while being cooled and solidified through a break ring made of a sintered body of ZrO ₂ .