JPS58221634A - Casting mold for continuous casting - Google Patents

Abstract

PURPOSE:To prevent the seizure of molten steel and to prevent the generation of cracking in a coating layer owing to sulfur attack by providing a coating layer of Mo or an Mo-based alloy on the inside surface of a casting mold made of copper for continuous casting. CONSTITUTION:A coating layer 2 of Mo or an Mo alloy is formed by electroplating or melt spraying on the inside surface of a casting mold 1 made of copper or a copper alloy for continuous casting of steel. More particularly, the coating layer is formed thickly in the upper part in the casting mold where the temp. is high and thinly in the lower part so that the casting mold is usable stably without embrittlement and peeling of the coating layer owing to the sulfur attack by a slight amt. of S contained in molten steel or mold powder and without seizure by the molten steel.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a continuous casting mold that has high high-temperature strength and prevents molten steel from seizing.

Continuous casting molds are usually made of copper or its alloy, and the surface of the mold body is coated with a surface coating layer made of 2.Kel or its alloy, which has various properties such as heat resistance and wear resistance. Kel or Ni-Kel alloys react with a small amount of sulfur present in mold powder or molten copper, causing a phenomenon called sulfur attack, which can cause cracks in the surface coating layer, and other problems. The molten steel or solidified shell in the mold may cause seizure. Seizure of molten steel or solidified seals must be avoided as this can be a major cause of breakouts.

The present invention aims to provide a mold which is not damaged by sulfur and which does not cause seizure of molten steel or solidified shell.
The gist thereof is a continuous casting mold characterized in that a coating layer of molybdenum or a molybdenum-based alloy is attached to the inner surface of a mold body made of copper or copper alloy.

The continuous casting mold of the present invention has a mold body (1
) is provided with a molybdenum or molybdenum-based alloy coating layer (2) on the inner surface, and the molybdenum or molybdenum-based alloy coating layer (2) on the inner surface is plated,
Attach by thermal spraying or other appropriate means.

While the mold for continuous casting is being used normally, its surface temperature will be 270~270°C even in the high part (usually the meniscus part).
In this range, molybdenum or molybdenum-based alloys have sufficient strength and high wear resistance.

In addition, if the molten steel or the solidified shell that has already formed breaks through the mold powder film and comes into direct contact with the molybdenum or molybdenum-based alloy coating layer (moisture) due to the above-mentioned trouble, that part will rapidly become high temperature. As a characteristic of molybdenum, it reacts with small amounts of sulfur and hydrogen sulfide present in mold powder or molten steel to produce molybdenum disulfide, and reacts with oxygen in the atmosphere to produce molybdenum oxide.

This molybdenum disulfide has excellent high-temperature lubricity, and molybdenum oxide is volatile and will evaporate and scatter at temperatures above about 400°C, so the molten steel or solidified seal will not seize on that part.

In this way, the present invention takes advantage of the disadvantageous properties of molybdenum, in that molybdenum is easily oxidized at high temperatures and the oxidized oxidation is easily volatilized and scattered. In addition to pure molybdenum, a molybdenum-based alloy containing one or more of various elements such as beryllium, 2, 2, 4, cobalt, iron, vanadium, niobium, di, ruconium, and titanium is used.

In addition, as mentioned above, the molybdenum or molybdenum-based alloy coating layer (2) is gradually consumed by oxidation or sulfidation during use, and since the consumption is large at high temperatures, The thickness of the coating layer (2) is
That is, the mold may have a configuration as shown in FIG. 2, in which the layer thickness increases toward the upper part of the mold.

Furthermore, in order to prevent the coating layer (2) from peeling off and to improve the heat resistance and abrasion resistance of the side surface of the mold, a part or all of the side surface of the mold is coated as shown in FIGS. 3 and 4. There is also a form in which the covering layer is rolled up into a length.

In particular, when used as the short side mold of a variable width assembly mold in which the short side mold is sandwiched between two opposing long side molds and the short side mold is movable, the wear resistance of both side surfaces is Therefore, it is desirable to use the form shown in ζζ in FIG. 4 so that the reduction in width shrinkage due to molybdenum, which has high high-temperature strength, and the lubrication effect due to the formation of molybdenum disulfide ξζ described above are expected.

As described above, according to the present invention, the inner surface of the mold is coated with molybdenum or a molybdenum-based alloy coating layer, which maintains sufficient strength and wear resistance during normal operation. The coating layer is also made brittle by the sulfur contained in the molten steel or mold powder; It also has a self-lubricating effect due to the composition of molybdenum-1 oxide, which is easy to volatilize and flake off, and molybdenum disulfide-based alloy, which has high lubricating properties.
C. The solidified shell does not cause seizure and breakout, so safe operation is possible at all times.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the mold of the present invention, Fig. 2 is a side view showing the same modification, and Figs. A perspective view of something. In the figure, (l): Mold body (2): Coating layer Patent applicant: Mishima Kosan Co., Ltd. Representative: Noriharu Ariyoshi Figure 1 Figure 3 Figure 2 Figure 4

Claims (1)

[Claims]! A mold for continuous casting, characterized in that a coating layer of molybdenum or a molybdenum-based alloy is attached to the inner surface of a mold body made of copper or copper alloy. 2. The continuous casting mold according to claim 1, wherein the molybdenum or molybdenum-based alloy coating layer becomes thinner from the top to the bottom of the mold.