JPS61266154A - Continuous casting method for hollow clad steel - Google Patents

Abstract

PURPOSE:To cast continuously a hollow clad steel pipe having a coating on the outside layer at a low cost with good productivity by guiding a molten steel shell formed in a curved guide path emitted from a low-level mold for a molten steel to a high-level mold, coating the shell with a different molten steel and guiding the coated shell thereby solidifying the same. CONSTITUTION:The molten steel emitted from the low-level mold 1 for the molten steel forms the shell 6a in the curved guide path 5 and is guided to the rear-stage mold 2 by passing through an outside surface grinder and a heater 7. The different molten steel is coated on said shell in the mold 2 to form the hollow clad steel pipe 10 having the coating on the outside layer. The hollow clad steel pipe 10 is thus continuously cast at the low cost with the good productivity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for continuously casting hollow clad steel.

[Conventional technology]

Clad metal phases of composites in which one metal is entirely covered with another metal and the interfaces are metallurgically bonded are known. Here, the metal to be covered is called the base material, and the metal to be covered is called the coating material. Conventional methods for producing such a rad metal material include a method of depositing a coating +2 on the matrix under vacuum conditions and hot rolling it to make it adhere, and a method of applying a coating material to the base layer through a buffer. A method using explosive bonding in which the sheathing material is impact-bonded to the base material using the explosion pressure of the installed explosives, a method using overlay welding in which the sheathing material is welded to the base material by various types of overlay welding, and a method in which the base material is placed in a mold and molded. There are methods such as casting, in which a molten covering material is injected between the base material and the base material.

[Problem that the invention seeks to solve]

However, in all of the above conventional methods, a clad metal material is obtained by joining a coating material to a single base material, and continuous production is not possible. Therefore, there were disadvantages in that the productivity was extremely poor and the yield was also low. In addition, the method using rolling has the disadvantage that the types of coating materials that can be manufactured are relatively limited, and the method using explosive bonding produces a loud explosion sound.
The drawback was that it could only be used when manufacturing relatively small items in a specific location. Furthermore, the method using overlay welding is
There was a drawback that appropriate consideration was required for construction and quality control such as selection of welding materials, welding construction method, and heat treatment after welding. Furthermore, in the most commonly used casting method, the amount of molten steel injected is small and the amount of heat retention is small, so it is necessary to improve the bonding properties at the interface. For this purpose, a special heating device such as electromagnetic induction heating is required, resulting in an increase in the size of the equipment and a rise in equipment costs.

The present invention has been made to improve and eliminate the above-mentioned drawbacks of the conventional method, and it is an object of the present invention to provide a manufacturing method that can continuously cast hollow clad steel using simple equipment.

[Means for solving problems]

A means for solving the problems of the present invention is to arrange a low front mold and a high rear mold side by side, and to form a curved guide path for the slab to pass from the front mold to the rear mold. Then, the slab for base metal drawn out from the former mold is passed through the rear mold along the curved guide path while keeping the unsolidified molten steel inside, and is pulled upward, and then the slab for base metal is placed inside the latter mold. By supplying molten steel for coating of different materials, hollow clad steel with a coating material bonded to the outer layer of a hollow base material is continuously cast.

[For production]

The effect of the present invention is clear from the embodiment shown in FIG.

To explain based on this example, the base material slab 6 pulled out from the former mold 1 is cooled on the outer surface side to form a solidified shell 6a, and the inside thereof remains unsolidified. In this state, when the base material slab 6 is passed into the rear mold 2 along the curved guide path 5, only the solidified shell (hollow base material) 6a is pulled out, and the unsolidified molten steel 6b is transferred to the front mold 1 at the height of the hot water supply. stays at the same height position. In this state, by supplying molten steel for coating, which has a different material from the base material slab 6, into the rear mold 2, the molten steel for coating has a thickness corresponding to the dimension between the rear mold 2 and the solidified shell 6a. It is possible to continuously cast hollow clad steel 10 coated with

The method of the present invention will be explained below based on the embodiments shown in the drawings.

〔Example〕

FIG. 1 is a schematic diagram showing the main parts of continuous casting equipment to which the method of the present invention is applied. As shown in the figure, this equipment has a lower front mold 1 and a higher rear mold 2,
A curved guide path 5 consisting of a plurality of sets of pinch rolls 3 and pulling straightening rolls 4 is arranged between the two. At the end side of this curved guide path 5, the pulling straightening roll 4
A surface grinding device and a heating device 7 for the base material slab 6 cast from the front mold 1 are disposed between the mold 2 and the rear mold 2. The surface grinding device and the heating device 7 are not necessarily necessary if the surface of the base material slab 6 can maintain compatibility with the molten steel for the coating material. The reason why the second mold 2 is placed higher than the first mold 1 is that better slab quality can be obtained by surface coating the curved portion after straightening it.

A tundish 9 for supplying molten steel supplied from a ladle 8 to the front mold I is arranged above the front mold 1. Also, directly above the rear mold 2, there are a plurality of pairs of pinch rolls 1 for pulling out the hollow clad steel 10.
A tundish 13 for supplying molten steel supplied from the ladle 12 to the subsequent mold 2 is disposed diagonally above. Molten steel is supplied from the tundish 13 to the subsequent mold 2 through a runner 14 provided on the side of the mold 2. Said ladle 8 and 12
The molten steel in the ladle 8 is made of different materials, and the molten steel in the ladle 8 is used for the base material, and the molten steel in the ladle 13 is used for the coating material.

Next, a method for continuously casting hollow clad steel 10 using this equipment will be explained.

First, the base material slab 6 pulled out from the former mold 1 is
It is guided into the rear mold 2 by the curved guide path 5.

The outer surface of the base metal slab 6 is cooled as it advances through the guide path 5, and solidification gradually progresses inside. and,
On the terminal end side, the surface grinding device and the heating device 7 remove the surface sgale of the solidified shell 6a, and heat the solidified shell 6a and unsolidified molten steel 6b to maintain them at a predetermined temperature.

in the rear mold 2, on the inner surface of the mold 2;
Molten steel for the covering material is supplied from the tundish 13 to the outer surface of the solidified shell 6a via a runner 14, and the molten steel for the covering material is joined to the solidified shell 6a of the base slab 6. At this time, by rotating the latter mold 2, it is possible to improve the interfacial bonding between the solidified shell 6a and the covering material 15. On the other hand, in the portion that contacts the latter mold 2, solidification of the molten steel for coating material progresses due to cooling by the mold 2. The clad steel 10 with the coating material 5 bonded to the solidified shell 6a of the base slab 6 is pulled out above the rear mold 2 by the pinch rolls 11. In this case, the unsolidified molten steel 6b of the base material slab 6 maintains the same level as the hot water supply level of the preceding mold 1.

Then, it adheres little by little to the inner surface of the solidified shell 6a and is pulled up. An amount of unsolidified molten steel corresponding to the amount pulled up 6
b is sequentially replenished from the front mold 1 side, and the unsolidified molten steel 6h in this portion is always kept at a constant temperature (for example, about 1500° C. for low carbon ordinary steel). For reference, the outer surface temperature of the solidified shell 6a immediately before the rear mold 2 is about 1000°C in the case of the low carbon ordinary steel.

Therefore, the clad steel 10 pulled out from the rear mold 2
As shown in FIG. 2, it is hollow and allows for continuous casting with excellent productivity and high yield. In that case, the thickness of the solidified shell 6a of the base material slab 6 and the thickness of the covering material 15 can be arbitrarily set by adjusting the drawing speed. In this equipment, the guide path 5 for the base material slab 6 is formed in a curved shape, and the radius of curvature of the guide path 5 must be taken into account when determining the drawing speed.

The hollow clad steel 15 cast in this manner is cut into a predetermined size and processed into a ring-shaped product through a soaking furnace, a second punching machine, a tube expander, a stretch resuser, etc.

By the way, the present invention is not limited to the above-described embodiments, and can be modified as appropriate. For example, it is also possible to produce hollow clad steel with a rectangular cross-sectional shape.

〔Effect of the invention〕

As explained above, according to the present invention, hollow clad steel can be continuously cast, productivity can be significantly improved, and product costs can be significantly reduced. Furthermore, the entire nature of this type of continuous casting technology has been largely elucidated, and quality control is relatively simple.

[Brief explanation of drawings]

FIG. 1 is a schematic view showing the main parts of continuous casting equipment to which the present invention is applied, and FIG. 2 is a cross-sectional view of hollow clad steel cast by the equipment. 1... Front stage mold 2... Back stage mold 5...
- Curved guide path 6... Slab for base material 6a... Solidified shell (outside N of hollow base material) 6b... Unsolidified portion 15... Covering material 10...
・Hollow clad steel

Claims (1)

[Claims] 1. A low-level front mold and a high-level rear mold are installed side by side to form a curved guide path for the slab from the front mold to the rear mold, and the base material slab to be pulled out from the front mold is not placed inside the mold. While the solidified molten steel remains, it is passed through the rear mold along the curved guide path and pulled upwards.
A continuous casting method for hollow clad steel, characterized in that a coating material is bonded to the outer layer of a hollow base material by supplying molten steel for coating, which has a different material from that of the slab for the base material, into a subsequent mold.