JPH06320289A - Joining method for titanium or titanium alloy sheets - Google Patents

Abstract

PURPOSE:To improve joint strength and to easily join the titanium or titanium alloy sheets or titanium clad steels by performing seam resistance welding and then, carrying out arc processing along the weld line. CONSTITUTION:The titanium or titanium alloy sheets T1 and T2 are joined together by direct or indirect seam resistance welding. Afterwared, an indentation end 2 of roller electrodes 4a and 4b is melted by using an arc processing torch 5 or melting processing is carried out so as to fill up an indentation 1 by using filler metal 6. Further, although a linear structure remains on a nugget 3 of a joint, when stress is applied in this state, there is a case where rupture is caused. When arc welding is then performed along the indentation 1, the nugget 3 is heated above the recrystallization temperature 500 deg.C, the linear structure disappears, the rupture of the joined surface is eliminated and the joint strength is improved. Consequently, stress concentration of the indentation 1 part is avoided and simultaneously, external appearance is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin titanium or titanium alloy plate and a method for lap-bonding them with a titanium clad steel, for example, a plate thickness of 0. 2 to 2.0
Used for joining mm or titanium alloy plates.

[0002]

2. Description of the Related Art Titanium or titanium alloy plates have a beautiful appearance (silver white), excellent corrosion resistance, light weight and high specific strength.
Due to its good workability, it has come to be used in a wide range of fields.

However, since titanium is expensive, the plate thickness is becoming thinner and thinner, and titanium clad steel in which ultra-thin (1.0 mm or less) titanium is joined to the steel base material is used for members requiring strength. To be done. When joining titanium or titanium alloy plate of this thin plate and thin titanium clad steel of titanium mixture, melt-through occurs in arc welding that is generally used, and in titanium clad steel, a large amount of Fe, which is the base material steel, is welded. A large amount of Fe / Ti intermetallic compounds and compounds such as TiC and TiN which are dissolved in the metal are generated, and this makes the weld metal brittle, so that it cannot be practically used.
Therefore, in recent years, resistance welding, which does not cause burn-through or mixture of Fe and the like and can be joined with high efficiency, has been adopted.

[0004]

Of the resistance welding, spot welding cannot be used in places where airtightness is required.
The joint strength of the entire structure is also low. Therefore, the application area is limited. In the seam welding, the airtightness is good, but in general, since pressure is applied by the roll electrode to join, an indentation is formed. In particular, a titanium plate has a large dent since it has a lower yield strength at high temperatures than stainless steel. This indentation reduces the plate thickness and often leaves a linear structure on the resistance-welded joint surface, which causes a problem in joint strength. Further, the impression of the roll electrode may not be preferable in appearance.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a construction method capable of improving joint strength and facilitating the joining of titanium or titanium alloy of a thin plate having a clean appearance and thin titanium clad steel of a titanium composite material portion. .

[0006]

That is, the gist of the present invention is that, in lap welding of titanium or titanium alloy plates, after seam resistance welding is performed, arc treatment is performed along the seam resistance welding line. And a method for joining titanium or titanium alloy plates. As the resistance welding, the direct seam resistance welding method shown in FIG.
Alternatively, the indentation 1 formed on the roller electrodes 4a, 4b, 4c by the indirect seam resistance welding method shown in FIG.
A TIG or plasma arc process is performed as shown in FIGS. 1 (b) and 1 (c).

[0007]

In the method of the present invention, after the titanium or titanium alloy plates T1 and T2 are joined by direct or indirect seam resistance welding shown in FIG. 1 (a),
The indentation ends 2 of the roller electrodes 4a, 4b, 4c are melted or melted by using a filler material 6 so as to fill the indentations 1. This avoids the concentration of stress in the indentation 1 portion and at the same time improves the appearance. In the figure, 5 is an arc processing torch, 8
Indicates weld metal.

Further, as shown in FIG. 3A, in the nugget portion 3 of the joint obtained by seam resistance welding, a linear structure 7 often remains on the joint surface. When stress is applied in this state, the linear structure 7 may break, but when arc welding is performed along the indentation 1 generated in the roller electrodes 4a, 4b, 4c, the nugget 3 has a recrystallization temperature of 500 ° C. or higher. As shown in FIG. 3B, the linear structure 7 remaining on the joint surface disappears, the joint surface is not broken, and the joint strength increases. In addition, if the arc treatment is performed immediately after the seam resistance welding is completed, the thermal efficiency is improved and it is more efficient.

[0009]

EXAMPLES The present invention will be described below with reference to examples. Titanium plates of various thicknesses (JIS TP28C), or titanium clad steel in which a titanium base plate and a steel base material are clad with a titanium mixture of 0.2 mm, are directly seam resistance welded or indirect seam resistance welded, respectively. The above method was carried out three by three. After that, one sheet melts the indentation part of seam resistance welding with TIG or plasma arc without filler material,
On the other sheet, a filler material (wire) equivalent to the base material component was melted so as to fill the indentation.

[0010] JI
Tensile-shear test pieces of welded joints according to S Z3136 were sampled and the strength and fracture position were investigated. Width of all test pieces is 2
The size was 0 mm and the length was 200 mm. Note that the strength is per cross-sectional area of the thin plate thickness of the laminated plate, and even in the case of breakage from the indented portion of the roller electrode or the nugget portion of seam resistance welding, it is the strength per cross-sectional area of the thin base material. . These are summarized in Table 1.

[0011]

[Table 1]

When arc treatment was performed after seam resistance welding, which is an example of the present invention in the table, the fracture positions were base metal fractures irrespective of the presence or absence of the filler material, and compared with the comparative example of seam resistance welding only. The strength was high and the joint strength was significantly improved. In addition, the appearance of the roller electrode indentation became inconspicuous,
It became a beautiful weld bead.

In the comparative examples, only seam resistance welding was used. 1-3 are direct seam resistance welding, No.
4 to 7 are examples of indirect seam resistance welding. All of these had a low value because they were broken at the indentation of the roller electrode and the nugget portion. In addition, the roller electrodes had large indentations and had a poor appearance.

[0014]

According to the joining method of titanium or titanium alloy plate of the present invention, joining of titanium or titanium alloy plate and titanium clad steel with improved joint strength and good appearance can be carried out easily.

[Brief description of drawings]

1A is a cross-sectional view of a direct seam resistance welding portion, FIG. 1B is an example of arc treatment without direct welding material after direct seam resistance welding, and FIG. 1C is a welding material after direct seam resistance welding. This is an example of performing arc processing with the presence.

FIG. 2 is a cross-sectional view of an indirect seam resistance weld.

FIG. 3A is a diagram showing a linear structure of a nugget after seam resistance welding is completed. (B) is a figure which shows that the linear structure disappeared by recrystallizing the nugget.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Indentation 2 Indentation end 3 Nugget 4a, 4b, 4c, 4d Roller electrode 5 Arc processing torch 6 Filler material 7 Linear structure 8 Weld metal T1, T2 Titanium plate

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location B23K 31/00 A // B23K 103: 14 (72) Inventor Noriorou Takahashi San Tsukiji, Chuo-ku, Tokyo 5-5 No. 4 Research Laboratories, Nippon Steel Welding Industry Co., Ltd. (72) Inventor Seiichi Soeda 2-6-3 Otemachi, Chiyoda-ku, Tokyo Shin Nippon Steel Co., Ltd. (72) Inventor Yasuo Takahashi Chiyoda, Tokyo 2-6-3 Otemachi, Ward Shin Nippon Steel Co., Ltd.

Claims (1)

[Claims] 1. A method for joining titanium or titanium alloy plates, characterized in that, in lap welding of titanium or titanium alloy plates, seam resistance welding is performed and then arc treatment is performed along the seam resistance welding line.