JPH0677831B2 - High efficiency slab assembly method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a slab assembling method which is efficient in producing a rolled clad steel plate of titanium or the like.

(Prior Art) As to a method for producing a clad steel plate, as shown in FIG. 3, a carbon steel or a low alloy steel is used as a base material 1 and a laminated material 2 is formed on the base material.
A method of manufacturing a clad steel sheet by placing the steel sheet on a roll and rolling it is disclosed in JP-A-59-19738. Further, in Japanese Patent Laid-Open No. 57-168791, as shown in FIG.
There is also disclosed a method of producing a clad steel by superposing a laminated material 2 on the above and subjecting it to ultra-high-power electron beam welding 10 to integrate and roll it. Further, in Japanese Patent Laid-Open No. 57-115991, as shown in FIG. 5, a base material 1-a laminating material 2-a release agent-a laminating material 2-a base material 1 are laminated in this order so as to be vertically symmetrical. A method is also disclosed in which the four surfaces are sealed and welded 9, and the base plate 7 is applied to the four circumferences of the base material, and the edges are welded to ensure the sealing property during heating or hot working and hot rolling. In addition, the explosive pressure welding method is widely known as a method for producing clad steel.

(Problems to be Solved by the Invention) As shown in FIG. 3, a method of producing a clad steel plate by placing a laminated material 2 on a base material 1 and rolling it is simple, but is combined with the base material 1. Since the material 2 is not joined, it cannot be applied to the production of a titanium clad steel sheet having a large difference in elongation between the base material and the laminated material at a high temperature. When the base material and the laminated material are overlapped and directly welded from the periphery or the upper part of both, it becomes dissimilar material welding, for example, when the laminated material is titanium,
Brittle intermetallic compounds TiC, TiN, and TiFe are formed in the weld, and joining is not performed reliably.

Further, as shown in FIG. 4, the method of integrating the base material 1 and the laminated material 2 by performing super-high power electron beam welding cannot be applied to the production of the titanium clad steel plate as described above, and is simple. Although it seems to be a method, there is a problem that it is expensive in terms of equipment and cannot be applied to the production of long or wide clad steel plates.

A method without welding different materials is shown in Fig. 5, but if the contact plate 7 is applied to the side surface of the base material 1 and the edge is welded in this way, the contact plate is not in close contact with the side surface, and the pressure at the time of reduction is reduced. This plate cannot be applied to the production of clad steel plate itself, because the plate cannot withstand it and is sure to peel off, and as a result, the plate is caught on the rolling roll and the rotation of the roll stops, so rolling must be stopped. The biggest problem of this method is that it requires a step of applying a release agent in order to form a sandwich, and when the joining material is titanium, it is difficult to fix the joining material.

The widely known explosion pressure welding method uses the momentary high pressure associated with explosive explosives, but in practice it requires expensive equipment and safety measures, and it is easy from the viewpoint of noise pollution. It is difficult to adopt.

The present invention has been made to solve the problems in fillet full circumference welding of the rolling slab manufacturing method, and the fillet full circumference welded portion is strong and defect-free in a short time with relatively simple equipment and method. It provides a smooth rolling slab.

(Means for Solving Problems) The gist of the present invention is that when a base material, which is a carbon steel or a low alloy steel, and a laminated material are overlapped and the circumference thereof is subjected to seal welding around the entire area, the area is larger than that of the base material. A laminated material of the same size as the thin sheet is placed on the base material through a thin sheet of carbon steel with a small and low carbon, and the side surface of the laminated material has a square cross section and has a clad surface with the same composition as the laminated material. The steel is brought into close contact, and the side surface of the laminated material and the clad surface of the square clad steel are subjected to fillet full-circle arc welding with a molten material of the same kind of composition as the laminated material,
A high-efficiency slab assembling method is characterized in that the base metal portion of the square clad steel and the slab base metal are subjected to fillet full-circumference arc welding with the same type of molten material.

(Working) In the present invention, the base material indicates a material before assembly, and the slab indicates a state after assembly and before rolling.

An example of the slab assembly order in the present invention will be described.

First, a thin plate of low carbon steel having a slightly smaller area than the base material is placed on the base material. This is to reduce carburization from the base material to the rolling joint. Then, put the laminated material of the same size on it. At this time, the gap between the base material and the laminated material is made an inert gas atmosphere. After that, as shown in FIG. 1, a rod-shaped clad steel having the same composition as that of the laminated material and having a rectangular cross section is closely attached to the side surface of the laminated material.

FIG. 1 is a vertical sectional view of an example of a slab. This is composed of a base material 1, a laminated material 2, a clad steel 3, a low carbon steel 4, and a fillet weld portion 6. Considering the strength of the fillet weld, the size of the clad steel that is closely adhered to the side surface of the laminated material may be set to about 1/2 of the plate thickness of the laminated material. If the clad thickness is too thin, it may peel off after welding, so 3 mm or more is desirable.

As a welding method, when the laminated material is titanium, fillet welding between the laminated material and the clad surface is performed by gas shield arc welding. In the case of stainless steel, gas shielded arc welding, latent arc welding, or manual welding may be used.

The fillet welding of the carbon steel or low alloy steel part of the clad steel and the base metal made of carbon steel or low alloy steel that adheres closely to the side surface of the laminated material is gas shielded arc welding regardless of whether the laminated material is titanium or stainless steel. Alternatively, either latent arc welding or manual welding may be used. Welding of the laminated material and the clad surface uses the same kind of composition as the molten material. For example, when the joining material is titanium, a molten material of titanium or titanium alloy is used. In the case of stainless steel, an austenitic melt is used when the composite material is austenite, and a ferritic melt is used when it is ferritic.

The welding of the carbon steel or low alloy steel portion of the clad steel and the base material made of carbon steel or low alloy steel uses the same level of molten material in any case. As the welding sequence, either the fillet full circumference seal welding between the carbon steel or low alloy steel part of the clad steel and the base material of the slab, or the fillet full circumference seal welding of the mating material and the clad surface, or You may go at the same time.

When the composite material is stainless steel, it is generally possible to perform dissimilar material welding between stainless steel and carbon steel or low alloy steel, but it is usually not used in parts where mechanical performance is important. This is because cracks occur inside due to lack of ferrite in the weld metal. If hot rolling is performed with internal cracks, the rolling pressure may not be able to be endured and cracks may open, and the base material and the laminated material may separate. In order to prevent the occurrence of cracks, there is a method of compensating for the deficiency of ferrite by using a high-grade melting material, but this method is not preferable because it will eventually cost the product.

From the above, it is possible to reduce the product price without cracking by using the molten material of the same kind of components through the angular clad steel.

After the assembly and welding are completed in this way, hot rolling is performed to obtain clad steel.

Hereinafter, the effects of the present invention will be described more specifically by way of examples.

(Example) Table 1 shows each material of the clad steel used. The clad steel in Fig. 2 has a thickness of 1 for the laminated material with a ratio of 1: 1 in the vertical and horizontal directions.
/ 2 and the clad thickness was 3 mm.

Table 2 shows the assembly method used. In addition, as a comparative example, a method of rolling by simply stacking the laminated material on the base material shown in FIG. 3 (this is referred to as A method) and a sandwiching method shown in FIG. And rolling (referred to as method B) were used. In addition, as a criterion, it was judged whether or not titanium clad steel was manufactured.

Table 3 shows the results of hot rolling.

The slab constructed by the clad steel adhesion method according to the present invention could be hot-rolled without any problem and a good titanium clad steel could be obtained. In the method A used as a comparative example and rolling only by laminating the laminated material on the base material, the base material and the laminated material were separated during the hot rolling, and the titanium clad steel could not be obtained. Further, in the method B in which the rolling plate is applied to the side surface and rolled, the rolling plate was peeled off and caught on the roll during rolling, and therefore hot rolling was stopped.

Although the above is an example of titanium, the present invention is naturally applicable to other clad steels other than titanium.

(Effect of the Invention) The high-efficiency slab assembling method according to the present invention is capable of reliably performing fillet full-circumference welding without defects and efficiently, and capable of obtaining a good clad steel after hot rolling. .

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an example of a slab, FIG. 2 is an enlarged view of clad steel adhered to a laminated material, and FIGS. 3 to 5 are slab sectional views showing a conventionally used method for producing a clad steel plate. Is. 1 ... Base material, 2 ... Laminated material, 3 ... Clad steel, 4 ...
… Low carbon steel, 5 …… Clad surface, 6 …… Fillet weld, 7
…… Plate, 8 …… Plate weld, 9 …… Sealed weld, 10…
… Electron beam welds.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Koike 5-10-1, Fuchinobe, Sagamihara-shi, Kanagawa Inside Nippon Steel Co., Ltd. Technical Research Center (56) (56) References Japanese Patent Publication No. 50-16308 B2)

Claims (1)

[Claims] 1. When a base material, which is a carbon steel or a low alloy steel, is overlaid with a laminated material, and the entire periphery thereof is welded by a seal, a thin plate of carbon steel having a smaller area and a lower carbon content than the base material is used. Laminated material with the same dimensions as the thin plate is placed on the base metal, and the side surface of the laminated material is adhered to the side of the laminated material and the clad steel having the clad surface of the same kind of composition as the laminated material is adhered to the side surface of the laminated material. The fillet full-circle arc welding is performed on the clad surface of the steel with the molten material of the same composition as the laminated material, and the fillet full-circle arc welding is performed on the base metal part of the square-clad steel and the slab base material with the molten material of the same composition. A highly efficient slab assembling method characterized by carrying out.