JPH08302B2 - Edge welding method of titanium clad steel plate - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a butt welding method for titanium clad steel plates, and more particularly to an end welding method for titanium clad steel plates for covering splash zones of pedestals in offshore structures.

[0002]

2. Description of the Related Art Titanium is used in chemical plants and aircraft parts because of its excellent corrosion resistance, and its use is expanding. However, its high price is a practical limitation. As a method of solving this, a titanium clad steel sheet having a base material of steel and a titanium surface has been recently used, and a pillar in an offshore structure is one example.

Titanium can be joined to a metal similar to titanium. For example, in joining titanium clad steel plates, when titanium and carbon steel or a low alloy steel as a base material are TIG welded by using an inert gas such as Ar or He. , F in molten metal
a large amount of e dissolves, Fe, Ti intermetallic compounds and TiC
Alternatively, it can be said that joining is impossible because a large amount of compounds such as TiN are formed and this embrittles the weld metal.

Therefore, in the case of conventional joining of titanium and steel materials or titanium clad steel plates, that is, in the case of so-called dissimilar material joining, joining by vacuum brazing or an insert material that does not form an intermetallic compound such as diffusion joining is used. Inserted and joined. For this reason, there are restrictions on the size, and at the same time, there are drawbacks such as inability to perform on-site joining, and expensive and low joining strength due to the use of precious metals such as electron beam welding. In addition, the winding attachment of the titanium clad steel plate to the pedestal is performed by welding and fixing the ends of the titanium clad steel plate, but various measures are taken because it is difficult to weld titanium and steel. Has been done. For example, JP-A-2-280970 and JP-A-2-280970.
As described in JP-A-280969, the joining of dissimilar materials is avoided to prevent such joining.

FIGS. 2A and 2B show a joining method of a titanium clad steel sheet 1 in which a commercial Ti composite material 3 is bonded to an upper surface of a base material 2 mainly composed of Fe. Is to weld the base material ends 4 and 4 of the clad steel sheet 1 and then
And a Ti spacer material 6 of the same quality as this are welded to form a Ti welded portion 7. However, in this joint, a gap 10 is formed between the surface of the base material end 4 and the spacer material 6, and seawater or the like enters the gap and corrosion of the base material 2 proceeds. In addition, these voids lower the bonding strength. on the other hand,
At the time of welding the joining material 3 and the spacer material 6, a part of the base material 2 is melted, and this is mixed into the weld metal of the welded portion 7 to form Ti.
A fragile layer of a compound such as C or TiN or an Fe—Ti intermetallic compound is formed, which causes cracking.

In order to prevent the formation of such a weld fragile layer,
As shown in FIG. 2 (b), the spacer material 6 is not welded to the composite material 3, but is only covered and placed between the composite materials 3, and is covered with a patch plate 8 on the upper part. The joint is formed by forming the overlap fillet weld 9 and joining. Patch plate 8
Is formed of titanium like the joining material 3 and the spacer material 6, so that the above-mentioned problem of forming the brittle layer in the overlap fillet weld 9 does not occur. However, since the joint plate 3 is welded to the joint material 3 in this joint, the welding structure is complicated and a considerable void 10 is formed, so that intrusion of seawater or the like into this void cannot be prevented. In addition, since the void portion is enlarged by the bending process, it is not suitable for a structure accompanied by processing.

[0007]

As described above, in the conventional joint portion of the titanium clad steel sheet, the inherent problem that it is difficult to weld the steel material containing Fe as the main component and the titanium material has not been solved. In particular, it was difficult to prevent corrosion of structures in seawater. The present invention, in order to improve the joint portion / joint structure of such a conventional titanium clad steel plate,
For example, when winding and using in the splash zone of the pedestal of an offshore structure, prevent the ingress of seawater, etc., and adopt a special process such as in-reactor joining when joining different materials between titanium and steel materials or titanium clad steel plates. In order to provide a method for forming an end joint part of a titanium clad steel plate which has no brittle layer and is excellent in corrosion resistance, by a simple arc welding method using an inert gas such as Ar or He To do.

[0008]

The gist of the present invention is that, when titanium-clad steel plates are filleted or butt-welded to each other, the titanium-clad steel plates are provided with notches and cuts at the end faces thereof to form base metals. After filleting or butt-welding the groove portion, a titanium clad steel plate is inserted as a spacer material into the gap formed by the notch, and the dissimilar material welded portion is subjected to Ag-Cu based melting material in an inert gas atmosphere. It is a method for edge welding of a titanium clad steel sheet, which is characterized in that TIG welding is performed by using.

Incidentally, either or both of Li and Sn may be added to the above-mentioned molten material.

[0010]

Since titanium has excellent corrosion resistance, it is used in chemical plants, aircraft parts, etc., and its applications are expanding, but its practical limitation is that it is expensive.
Accordingly, as a member used in a corrosive atmosphere, a titanium clad steel plate made of a low alloy steel, a high tensile steel, or the like as a base material that plays a role of maintaining strength and titanium as a bonding material is used. Titanium to be used may be any one of 1 to 3 specified in JIS. Titanium clad steel plate
As described above, it is used for various devices, parts, and the like, but in constructing these, it is important to obtain a bonded portion that does not have a brittle layer and has a bonding strength as described above.

That is, when joining titanium clad steel plates to each other, a groove is formed in a base material (mild steel or alloy steel), the base materials are welded together using a molten material of the same quality, and the ends are formed from the groove. A wide cut is provided, a spacer material of a titanium clad steel plate is inserted into this cut, and in this welded portion, the base material and the spacer material are made of a molten material containing Ag-Cu as a main component.
Dissimilar materials are joined by IG welding and the gap is seal-welded. The width of the spacer material of the titanium clad steel sheet provided in the above-mentioned cut can be made wider than the groove width for joining the titanium clad steel sheet. This is to control the promotion of the formation of intermetallic compounds on the cladding surfaces of the base material and the composite material (Ti) due to the heat effect.
If this is approximately the same as the groove width, it promotes the formation of intermetallic compounds on the clad surface and deteriorates the interfacial strength. Therefore, it is necessary to make it wider than the groove width for joining the titanium clad steel plates.

As the melting material used for joining in the present invention, a material containing Ag-Cu as a main component as described above is used, and for example, BAg8 or BAg8A (Li: 0. 015
~ 0.3% added) type material. Sn for these materials
May be added, and Zn can be added as long as the workability is not impaired. However, when Zn is added, fume generation increases, so the addition amount is limited to a small amount.
Ag and Sn are used to keep the melting point low, prevent reaction with Fe and Ti, Cu improve joint strength, and Li is used to improve compatibility with mild steel.

In the present invention, a low melting point Ag--Cu based melt which does not form an intermetallic compound with titanium or steel is used, and the dissimilar material is welded to titanium and steel by the TIG welding method which has a faster heating rate than the brazing method. Therefore, the Ag-Cu based melting material is rapidly melted and immediately solidified, and is not melt-mixed with titanium or steel more than necessary, and a sound dissimilar material welded portion can be obtained.

[0014]

FIG. 1 shows an embodiment of a welded portion obtained by the welding method of the present invention. Figure 1 shows a titanium clad steel plate 1,
1 shows a state in which 1 is joined, and base materials (mild steel) 2 and 2 are TIG
Multi-layer welding is performed to form a welded portion 5. The width of the gap portion 12 formed by cutting the ends of the titanium clad steel sheets 1 and 1 is set to be larger than the groove width for joining the titanium clad steel sheets 1 and 1 in advance, and the titanium clad steel sheet to be inserted into the gap portion 12 The width of the spacer material 6 is the gap 1
It is installed slightly narrower than the width of 2, and the upper portion of the spacer material 6 and the laminated material 3 are TIG-welded with an Ti-melting material of the same quality in an atmosphere of an inert gas such as Ar or He to form a Ti-welded portion 7. To do. The Fe-Ti dissimilar material seal weld at the end is A
The dissimilar material welded portion 11 is formed by TIG welding with a molten material containing g-Cu as a main component using an inert gas such as Ar or He.
Since the dissimilar material welded portion 11 is line-joined, the joining strength is higher than that of brazing, and welding work can be performed on site.
In addition, since a material containing Ag-Cu as a main component is used, A
A component of the deposited metal containing g as a main component is obtained, and although Fe is penetrated, the amount thereof is small but an Ag-rich deposited metal is obtained.

The spacer material 6 and the upper portion of the laminated material 3 are made of the same quality T.
TIG welding is performed using an inert gas such as Ar or He with an i melted material to form a Ti welded portion 7, which is then covered with a backing plate material 8 and overlapped with the mating material 3 to form a fillet welded portion 9. And join. As a result, the welded portion of the clad steel sheet is:
Although there is a gap between the joining material and the backing material, a spacer material of the same titanium clad steel plate is installed at both ends at the ends, and it is completely sealed and welded, so that embrittlement and corrosion due to seawater intrusion into the weld can be prevented. .

[0016]

As described above, according to the present invention, it is possible to obtain a sound material without causing embrittlement of the welded portion and deterioration of corrosion resistance, which have been a problem in the dissimilar material seal welding of the end portion of the titanium clad steel sheet. Since the weld metal can be obtained by arc welding similar to the conventional one, its industrial effect is extremely large.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a procedure of welding an end portion of a titanium clad steel sheet according to the present invention.

FIG. 2 is a cross-sectional view showing a conventional method of joining titanium clad steel sheets. DESCRIPTION OF SYMBOLS 1 Titanium clad steel plate 2 Base material (mild steel) 3 Laminated material 4 Edge of titanium clad steel plate 1 Base material multi-layer welded portion 6 Spacer material 7 Ti welded portion 8 Patch plate material 9 Stacked fillet welded portion 10 Void 11 Different material welded portion 12 Gap

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Kazuo Sakai 2-6-3 Otemachi, Chiyoda-ku, Tokyo Within Nippon Steel Corporation (72) Inventor Seiichi Soeda 2-6-Otemachi, Chiyoda-ku, Tokyo 3 Within Nippon Steel Corporation (56) References JP-A-1-122674 (JP, A)

Claims (1)

[Claims] 1. When the titanium clad steel plates are filleted or butt welded with each other, a groove is provided at each titanium clad steel plate end face, and a notch is provided so that the base materials are filleted or butt welded at the groove part. A titanium clad steel plate is inserted as a spacer material into the gap formed by the notch, and the dissimilar material welded part is TIG welded using an Ag-Cu based melt in an inert gas atmosphere. Steel plate edge welding method.