JPS595385B2 - Continuous casting mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold used for continuous casting of low carbon steel, high carbon steel, stainless steel, special steel, etc.

In this type of continuous casting mold, heat-resistant and wear-resistant plating is applied to the inner wall surface of the mold base made of copper or copper alloy to protect the inner surface of the mold and prevent mold base steel from entering the slab. It is well known that this is possible.

In this case, the thicker the plated layer is, the better in terms of mold durability and prevention of deformation, as long as it does not deteriorate thermal conductivity, but if the plated layer is made too thick, heat cracks may occur on the plated surface during casting. There is a possibility that this will occur.

Therefore, in reality, there was a problem that it was not possible to obtain a sufficient plating layer thickness.

The present invention solves the above problems and provides molds with excellent durability.

In other words, the present invention is based on the fact that the occurrence of heat cracks in the mold plating layer is almost always limited to the vicinity of the meniscus where the surface of the molten steel contacts the inner wall of the mold during pouring. This was done based on the investigation of the fact that the molten steel gradually solidifies in the mold and begins to form a shell around the mold, starting from the middle of the mold and reaching its maximum towards the exit. In addition to preventing the occurrence of cracks, there is no risk of downward cracks, and by making the plating layer thick enough in areas where there is a risk of mold wear and deformation due to the growth of solidified shells, it is extremely durable. It is characterized by a mold that is rich in sexuality.

Here it is near the meniscus.

The thickness of the above-mentioned plating applied to the mold base is preferably set to a level not exceeding 2500 μm near the meniscus.

That is, according to research conducted by the present inventors, it has been found that heat cracks occur significantly when plating is applied to a thickness exceeding the above value, although this varies somewhat depending on the type of plating.

Hereinafter, actual examples of the present invention will be explained with reference to the drawings.

FIG. 1 is an inverted version of an embodiment of the invention, showing a longitudinal side view of one side of the mold.

1 is a mold base made of copper or copper alloy; 2 is plating applied to the inner wall surface of the mold base 1; A second plating layer 2 of an alloy containing at least one of nickel and cobalt as a main component and at least one of phosphorus and boron is applied to the second plating layer 2.

In addition, h'-these plating layers 2's2/
/ May be further plated with chrome.

The layer of plating 2 in the same figure is formed in a shape whose thickness gradually increases from the upper end to the lower end of the mold, thereby creating a difference between the thickness t near the meniscus 3 and the thickness T at the bottom. The first plating layer 2' is the first plating layer 2', the second plating layer 2 is the opening, and the thickness difference is provided between the two plating layers 2' and 2tt, so that the overall plating layer thickness is formed in the above shape. It shows what was done.

To apply such plating, the plating layer to have a difference in thickness must be made thick in advance and then cut into the desired shape, or the plating operation, such as electroplating, may be used. When plating is performed, the plate can be formed by plating with the plate appropriately inclined with respect to the surface to be plated (inner wall surface of the mold).

In addition, in Figure 2, E, H, H, and C, the inner wall surface of the mold base 1 is partially cut diagonally or in steps, and the entire surface is covered with the mold's original shape by filling in the cut parts. This is an example in which the layer thickness and T of the plating 2 are made different by ovalizing the plating 2 so as to form an inner wall surface. In addition, there are differences in thickness in the second plating layer 2.

Next, the effects of the present invention will be explained using actual cases.

The first and second plating layers 2' and 2 applied to the inner wall surface of the substrate at the long and short sides of the mold shown in Fig. 125 tons of carbon steel was made into
Continuous casting was carried out into a 5m x 300mm slab.

Molds A, E, and H are the openings in Figure 1, and mold B. F, I are C in the same figure,
Molds C, G, and J were made as shown in Figure A, and molds were made as shown in Figure E, respectively.

In addition, the thickness tl of the first and second plating layers in Table 1,
'r1 and t2. T2 is each plating layer 2'? 2//, the thickness near the meniscus tl + t2 and the thickness at the lower end T1. T2
It is expressed correspondingly.

For comparison, continuous casting was carried out in the same manner as described above using a conventional mold with a uniform thickness plating shown in the same table and M.

Table 2 shows the results of investigating the occurrence of heat cracks in each mold after the completion of the above continuous casting.

As explained above, the present invention prevents the occurrence of heat cracks by thinning the plating near the meniscus above the mold, and sufficiently thickening the plating below where cracks do not occur but there is a risk of wear and deformation. Since it is designed to deal with wear and deformation, the life of the mold can be significantly extended.

[Brief explanation of the drawing]

FIG. 1A, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20 have been inverted versions of embodiments of the present invention, and represent the vertical cross-sectional side of the mold side. In the figure, 1... Mold base length/short side, 2... Plating, 3
...Meniscus.

Claims (1)

[Claims] 1. Ni+Co, Ni+Co, Nlp, Ni+B on the inner wall surface of a mold base formed of copper or copper alloy. Co+P+Co+B, Ni+Co+P, Ni+Co+B
A mold for continuous casting, characterized in that the thickness of the plating layer of one or more of ICo+N i +P+ 8 is made thicker below than near the meniscus.