JPH0218935B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a continuous casting mold having constant surface properties and a method for manufacturing the same.

Continuous casting molds are usually of the type having various surface coating layers attached to the inner surface of the mold body made of copper or copper alloy on the side that comes into contact with molten steel.

Various methods have been adopted for forming this surface coating layer, such as a plating method and a thermal spraying method, but it is often preferable to use a thermal spraying method from the viewpoint of the abrasion resistance of the coating layer and the speed of operation. However, when applying a surface coating layer by thermal spraying, the mold body becomes warped due to the heat treatment performed after thermal spraying to improve adhesion or to remelt the self-fusing sprayed layer, as shown in Figure 1. Otherwise, deformation often occurs as shown in Figure 2. The sprayed layer 2 on the mold body 1 is normally a thin layer of 1 mm or less, so in order to finally finish the inner surface smooth, the inner surface should be lined along line A-A in Figure 1 or line B-B in Figure 2. If the sprayed layer 2 is polished to the position indicated by , there will be some areas where the sprayed layer 2 is completely removed and the base of the mold body 1 is exposed, and the sprayed layer 2 is present on the inner surface of the mold. Moreover, in some places, the mold has an uneven surface condition, with the mold body 1 being exposed as it is. After heating and deforming, the deflection is corrected to some extent by a mechanical method, but the thermal spray layer 2
Since it does not have much deformability, the deflection that can be corrected is small. In order to prevent such non-uniformity of the surface condition, it would be good in principle to apply the sprayed layer thick enough so that the base of the mold body will not be exposed even during subsequent polishing. Even if you try to thicken the sprayed layer, the adhesion is weak, especially since the mold body is made of a material with good thermal conductivity, and cracks may occur when deformed during subsequent heat treatment. As shown in Figure 3, C-C
The mold obtained by polishing to the line has a part a where a significantly thick sprayed layer 2 exists on the inner surface and a part a where most of the sprayed layer 2 is present.
This is not a practical solution because there are problems such as a part b where no water is present, and the thermally sprayed layer has poor thermal conductivity, and there are significant temperature differences at various parts of the mold's inner surface. .

The present invention aims to provide a mold and a method for manufacturing the same that solve the above-mentioned problems, and its gist is that a sprayed layer made of a self-fusing alloy is attached to the inner surface of a mold body made of copper or copper alloy. , a continuous casting mold characterized in that a nickel or nickel-based alloy plating layer is further attached to the upper surface of the sprayed layer, and a sprayed layer made of a self-fusing alloy on the inner surface of the mold body made of copper or copper alloy. After installation, it is heated and held, then a nickel or nickel-based alloy plating layer is applied to the top surface of the sprayed layer, and finally polished with a polishing amount within the thickness of the topmost nickel or nickel-based alloy plating layer. This is a method for manufacturing a continuous casting mold, which is characterized by the following.

The mold body used in the present invention is made of a copper alloy containing aluminum, zirconium, silver, etc. in addition to blunt copper, and the material of the sprayed layer is a self-fusing alloy having properties such as heat resistance and wear resistance. Furthermore, before applying a thermal spray layer to the mold body, an undercoat material made of a material compatible with the thermal spray material used, such as nickel or its alloy, may be applied by plating or other means.

In the present invention, as shown in FIG. 4, a sprayed layer 2 is first deposited on a mold body 1, and heated and held at 800-1000 DEG C. for 0.5-10 hours.

In addition to improving the adhesion between the mold body and the sprayed layer, this heating and holding is also a solution treatment for precipitation hardening copper alloys, and a remelting treatment for the sprayed layer made of a self-fusing alloy. In any case, the mold body is deflected by the heat treatment after thermal spraying, and then a nickel or nickel-based alloy plating layer 3 is attached to the upper surface of the thermally sprayed layer which has undergone deflection deformation. In this case, the bending deformation may be mechanically corrected to some extent prior to the plating process. The mounting thickness of the plating layer 3 is set to be thicker than the maximum amount of bending deformation. If the mold body 1 is made of a precipitation hardening alloy, be sure to add 300% to prevent aging precipitation, and if the mold body 1 is not made of a precipitation hardening alloy, as necessary to improve the adhesion of the plating layer 3. The mold is heated to ~500 DEG C. and then polished to a polishing amount within the thickness of the plating layer 3, as shown by line D--D in FIG. 4, to produce a mold with a smooth surface.

As described above, according to the present invention, when the surface of the mold is finally polished, there is no need to polish the sprayed layer, which is difficult to polish due to its high hardness, and only the top plating layer can be polished. This makes it easy to polish and finish, and the finished surface is made of nickel or nickel-based alloy over the entire area, and the underlying sprayed layer is not exposed, so the surface condition is uniform and there are no areas within the applied coating layer. The only difference in thickness is the plating layer, and the thickness of the sprayed layers is the same, so the temperature at each location on the surface is almost uniform. In other words, the plating layer is made of nickel or a nickel-based alloy and has good thermal conductivity, so even if the thickness of the plating layer varies slightly from place to place, the thickness of the sprayed layer, which has poor thermal conductivity, will spread over the entire surface area. If they are the same, there will be an almost negligible temperature difference.

[Brief explanation of drawings]

Figures 1 and 2 are explanatory diagrams of conventional molds;
The figure is an explanatory diagram of a case where the thickness of the sprayed layer is increased in a conventional mold, and FIG. 4 is an explanatory diagram of the manufacturing process of the mold of the present invention. In the figure, 1: mold body, 2: thermal spray layer, 3: plating layer.

Claims (1)

[Claims] 1. A thermally sprayed layer made of a self-fusing alloy is attached to the inner surface of a mold body made of copper or copper alloy, and a nickel or nickel-based alloy plating layer is further attached to the upper surface of the thermally sprayed layer. A continuous casting mold featuring: 2. The continuous casting mold according to claim 1, wherein the mold body is made of a precipitation hardening copper alloy. 3. On the inner surface of the copper or copper alloy mold body,
After attaching the thermal sprayed layer made of a self-fusing alloy, it is heated and maintained, and then a nickel or nickel-based alloy plating layer is applied on the top surface of the thermal sprayed layer, and finally the thickness is within the thickness of the topmost nickel or nickel-based alloy plating layer. A method for manufacturing a mold for continuous casting, characterized in that polishing is performed with a polishing allowance of . 4. The mold body is made of precipitation hardening copper alloy, and the heating after attaching the sprayed layer is the solution treatment heating of the mold body, and after applying the nickel or nickel-based alloy plating layer, the mold body is further heated for aging treatment. A method for manufacturing a continuous casting mold according to claim 3. 5. The method for manufacturing a continuous casting mold according to claim 3, wherein the heating after the thermal spray layer is attached is heating for remelting the thermal spray layer. 6 The mold body is made of precipitation-hardened copper alloy, and the heating after attaching the sprayed layer serves as the solution treatment heating of the mold body and the remelting treatment heating of the sprayed layer, and the mold body is made of a nickel or nickel-based alloy plating layer. 4. The method of manufacturing a continuous casting mold according to claim 3, further comprising performing an aging treatment on the mold body and a heat treatment to improve the adhesion of the plating layer.