JPS63101081A - Highly efficient welding method for titanium - Google Patents

Abstract

PURPOSE:To prevent the occurrence of weld defects and to improve welding efficiency by adding a filler to perform the welding by a preceding electrode and then, performing the fusion welding without filler metal by a multiple electrode TIG welding method by a succeeding electrode. CONSTITUTION:Filler wires 1 are molten and joined by the preceding electrode 2 and a bead 3 formed by the preceding electrode 2 is corrected by the fusion welding without filler metal and made to a satisfactory bead shape 9. Furthermore, when a plasma torch is provided ahead further the preceding electrode and the plasma preheating is performed, the still satisfactory welding can be performed. A satisfactory welded zone is obtained and the working efficiency can be improved by this method.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a highly efficient multi-electrode TIC made of titanium and titanium alloys.
Regarding welding methods.

[Prior Art] Currently, inert gas arc welding such as TIG welding and MIG welding is used as a practical method for welding titanium and titanium alloys, and TIG welding is mainly used.

Problems in welding titanium and titanium alloys are atmospheric pollution and the occurrence of blowholes, undercuts, etc.

Since titanium is an active metal, it easily oxidizes and nitrides when heated above 400℃ in the atmosphere, making it hard and brittle and significantly deteriorating the material properties.To prevent this, argon Welding is difficult because it requires a sufficient seal with an inert gas such as gas or helium gas.

Further, blowholes and the like occur due to inappropriate welding conditions, welding operations, groove shape, cleaning of the groove surface, etc., and the properties of welded joints deteriorate due to the occurrence of blowholes. In addition, if we try to increase the amount of heat input and the amount of penetration in order to improve welding efficiency, not only will the bead shape deteriorate, but defects such as undercuts are more likely to occur, so it is necessary to weld by reducing the amount of heat input. As a result, efficiency is extremely reduced.

For this reason, the actual cost of welding thick materials is extremely high, and it is no exaggeration to say that this is one of the factors inhibiting the expansion of titanium's uses.

As a means to solve this problem, Japanese Patent Application Laid-Open No. 56-84172 describes a high-speed welding method using one pool/two electrodes, in which welding is performed by alternately switching the welding current to two electrodes. However, this method requires advanced techniques such as adjusting switching timing and dealing with arc interference between electrodes, and the welding equipment is complicated and expensive.

Furthermore, Japanese Patent Application Laid-Open No. 53-56138 discloses a method for stabilizing the molten pool and improving welding speed by using one pool/two electrodes and balancing the arc from the trailing electrode with the arc force from the leading electrode. .

Although this method is technically possible, it is not necessarily easy to realize when considering the actual situation of on-site implementation.

Furthermore, multi-electrode technology has been developed to improve the efficiency of welding work. This is because of the 2-pull/2-electrode method, which allows the welding speed to be increased somewhat by preheating the leading electrode and deepening the weld penetration by the trailing electrode, but the effect is small.

[Problems to be Solved by the Invention] The present invention is a multi-electrode TIG welding method for welding thick titanium and titanium alloys. The present invention relates to a high-efficiency welding method for titanium that significantly reduces or eliminates welding defects such as, etc., and improves work efficiency by increasing the amount of welding per bus.

[Means for solving problems] The present invention is applicable to welding titanium and titanium alloys.

By adopting multi-electrode TIG welding, and giving the trailing electrode the role of welding with a name, and by giving it the function of correcting the shape of the filler-added welded bead with the leading electrode, the regulatory conditions for welding with the leading electrode can be improved. This method provides a highly efficient multi-electrode TIG welding method that allows deep weld penetration by combining preheating with plasma, and its gist is as follows. . That is, (1) in TIG welding of titanium, it is a high efficiency welding method of titanium by multi-electrode TIG welding, characterized in that filler addition welding is performed using a leading electrode and welding is performed with a filler using a trailing electrode, and (2) The preceding electrode is a plurality of preceding electrodes (
It is a highly efficient titanium welding method described in 1), and also in (3)
The highly efficient titanium welding method described in (1) and (2) above is characterized in that a plasma torch is provided further ahead of the leading electrode and plasma preheating is performed.

[Function, Examples] FIG. 11 shows a titanium plate 1, an electrode 2 and a filler wire 4.
Commonly used single-electrode TIG that performs fusion bonding using
It is a schematic diagram of welding. A well-shaped bead can be obtained with a single electrode at normal welding speeds, but as the welding speed increases, the penetration becomes shallower and the melting becomes unstable, resulting in the formation of irregular beads and welding problems such as blowholes. The presence of defects is also confirmed by X-ray transmission testing.

Figures 12 to 14 show previously reported measures to improve the above problem, and Figure 12 shows a normal TIG welding electrode 2.
A leading TIG electrode 6 is provided in front of the electrode to increase the weld penetration depth by preheating. Fig. 13 shows a 2-pull, 2-electrode system, which increases the amount of welding as well as the preheating effect of the leading electrode. can be expected to increase. Figures 12 and 13
Although the method shown in the figure can achieve a somewhat faster welding speed,
When the welding speed is increased, irregular beads occur, and no improvement in bead shape due to trailing arc can be expected.

Due to the quality of the welded parts, it was impossible to increase the speed. FIG. 14 shows a 1-pull, 2-electrode method, which allows deep penetration and is theoretically possible to increase speed. However, there are various technical issues such as arc interference, and considering the actual situation of on-site implementation, it cannot be said that the feasibility is necessarily high.

The present inventors have investigated various aspects and developed a multi-electrode TI that is easy to apply on-site and enables highly efficient and defect-free welding.
Discovered the G welding method.

FIG. 1 shows an example of the multi-electric tMTIG welding method by the present inventors, in which the shape of the weld metal bead 3 formed by the leading electrode 2 is corrected by using the trailing electrode 8 to modify the bead shape as shown in 9. , the leading electrode 2 is used to ease the welding condition constraints for optimizing the shape of the welded metal, making it possible to weld a large amount of welded metal, and the trailing electrode 8 is used to correct the shape and quality of the welded metal by naming. The mutual action of the electrodes achieves highly efficient welding without welding defects. FIGS. 2 and 3 are a sectional view of the harbor shown in FIG. If the bead shape formed in step 2 becomes an irregular bead as shown in step 3 in Figure 2, welding defects such as poor fusion will occur frequently at point 10 in conventional multi-electrode lamination welding, but this In the present invention, by modifying the bead shape with the trailing electrode 8, the bead shape is flattened as shown at 9 in FIG. 3, and there are no welding defects. FIG. 4 shows another embodiment of the present invention, in which a filler wire 4
In the method shown in Fig. 1, in which molten welding is performed using a single electrode, there is a limit to the increase in the amount of deposited metal even if regulations on welding conditions are relaxed. The amount of deposited metal is increased by carrying out the fusion welding of 4a in a 1 pull 1 electrode method, and the shape of the bead 3 formed by the leading electrode 2a is corrected to a flat bead by welding with a slant with the trailing electrode 8. This enables more efficient welding. The welding currents of the preceding electrodes 2 and 2a may be the same, but due to the material temperature etc., the welding currents of 2 and 28
Since the weld penetration depth is different for electrodes 2a and 2a, the current value of electrode 2 is the current value for single electrode welding, and the current value of electrode 2a is 1.0 to 1.5 times that of electrode 2 for multi-weld welding. It can be carried out.

Figures 5 to 7 are cross-sectional views of Hoho, Hehe, and Thoth in Figure 4, showing the cross-sectional shape of the bead formed by each electrode of the multi-electrode TIG welding shown in Figure 4. be. 8th
The figure shows another configuration of the present invention, which is a high-efficiency welding method using a plasma torch 11.

As a well-known high-speed, high-efficiency welding method, a multi-electrode TIG welding method in which the preceding TIG electrode has a heating function has recently been put into practical use, but heating with a TIG electrode has a planar preheating effect, but the heating depth is limited. Not suitable for shallow preheating of thick materials, etc. However, plasma heating has an advantage in welding narrow gaps in thick materials, which requires a large amount of welding, because it preheats deep parts. That is, as shown in FIG. 9, by taking advantage of the characteristics of plasma heating, which allows heating in a narrow range at a deeper depth than TIG heating, a plasma heating source is provided at the leading edge to achieve an optimal preheating effect, and the electrode 2 This material significantly increases the penetration depth and improves welding efficiency.

Each electrode and plasma heating source described in detail of the present invention includes:
They are arranged in series, and the distance between each electrode is 20 to 50 m.
Ta is preferred.

[Example Table 1 shows examples of welding conditions, welding efficiency, and welding quality during one-bus welding by TIG welding of titanium, comparing the conventional method and the present invention. The groove shape is as shown in FIG. 10. The welding method of the present invention allows the amount of welding (g/m1n) to be extremely large compared to conventional methods, and there is no welding defect.

[Effects of the invention] By adopting the method of the present invention, there are fewer welding defects and the welding efficiency can be improved by 2 to 4 times compared to the conventional single electrode TIG welding method. law, and has great industrial effects.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example in which there is one leading electrode and one trailing electrode in the present invention. FIG. 2 is a diagram showing a bead shape formed by the preceding electrode in FIG. 1. FIG. 3 is a diagram showing a bead shape after welding with an eggplant by the trailing electrode in FIG. 1; FIG. 4 is a diagram showing an example in which there are two leading electrodes and one trailing electrode in the present invention. FIG. 5 is a diagram showing a bead shape due to the leading electrode in FIG. 4. FIG. 6 is a diagram showing the bead shape after two-layer build-up using 28 electrodes in FIG. 4. FIG. 7 is a diagram showing the bead shape after welding with eggplant by the electrode 8 in FIG. 4. FIG. 8 is a diagram showing an example of the present invention having a plasma torch. FIG. 9 is a diagram showing the size of the heated part by the TIG electrode and plasma torch. FIG. 10 is a diagram showing the groove shape of the example. Fig. 11 shows a conventional embodiment, Fig. 12 shows another conventional embodiment, Fig. 13 shows another conventional embodiment, and Fig. 14 shows a further different conventional embodiment. Diagram showing. It is. 1: Titanium plate, 2: TIG electrode, 2a: TIGff! Pole, 3: Overlay bead, 4: Filler wire, 5: Bevel, 6
: TIG electrode for preheating, 7: Pool, 8: T for welding with latch
IG electrode, 9: Bead smoothed by tongue welding, 10
: Locations that cause welding defects, 11: Plasma torch.

Claims (3)

[Claims] (1) A high-efficiency welding method for titanium using multi-electrode TIG welding, which is characterized by performing filler addition welding with a leading electrode and tongue welding with a trailing electrode. (2) A high-efficiency titanium welding method by multi-electrode TIG welding according to claim 1, characterized in that the leading electrode is a plurality of leading electrodes. (3) In TIG welding of titanium, there is a multi-electrode TIG welding method in which filler addition welding is performed using one or more leading electrodes and tongue welding is performed using a trailing electrode. A highly efficient titanium welding method characterized by having a plasma torch and plasma preheating.