JPS6336994A - Method for relieving welding strain of titanium material - Google Patents

Abstract

PURPOSE:To improve the welding and working accuracy of titanium materials by heating and melting the rear side of the weld zone thereof in an inert gaseous atmosphere, then stopping the heating and allowing the molten part to solidify and shrink. CONSTITUTION:A weld strain is formed in a thick-walled titanium bracket 2 and the bracket is deformed to a position 2a when said bracket and a titanium shape material 1 are subjected to fillet welding 3b. The fillet weld zone 3b of the bracket 2 is heated at 6,000 deg.C by an arc 6 of a TIG arc 5 along the surface layer 4 on the rear side thereof at this time. The air in the heated part is shut off by the inert gaseous atmosphere of gaseous Ar, etc., and the surface layer part 4 is melted. While the inert gaseous atmosphere is maintained, the arc 5 is turned off and the molten part is allowed to cool and solidify. The strain of the bracket 2 is relieved by the internal compressive stress at this time and the welding and working accuracy of the titanium materials is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for removing welding strain from a welded portion formed on a titanium plate or titanium profile. It is particularly suitable for removing welding distortion from welded parts of thick titanium plates and titanium shapes.

<Prior art> In the conventional method, or in the manufacturing process of structures using thick titanium plates or titanium shapes for the outer shell structure of deep-sea submersible vessels, welding process and partial joint joints occur1, so this Removal became a problem. This is because welding distortion occurs in the welded part when the welded part solidifies. Conventionally, such welding distortions were removed by pressing small welded parts with a hydraulic press, or heating and softening large parts with a gas burner and pressing with jacks.

<Problems to be Solved by the Invention> However, when trying to forcefully correct welding distortion by pressing with a hydraulic press, titanium materials often crack due to their small Young's modulus. Furthermore, if an attempt is made to remove welding distortion by heating and softening with a gas burner, it is inevitable that oxides or nitrides will be formed in the heated part by the gas burner, making it even more brittle.

Therefore, although various methods have been tried to eliminate such welding distortion at the welded portion, no suitable method has been found, and a new and improved method for eliminating distortion has been desired.

The present invention has been made in view of the problems of the prior art, and it is an object of the present invention to provide a method for removing welding distortion of a titanium material by easily and reliably removing the welding distortion of a welded part of a thick titanium material. shall be.

Means for Solving the Problems> The method for removing welding strain on titanium materials according to the present invention is configured by heating and melting the back side of a welded part of a titanium member with welding strain in an inert gas atmosphere, and then heating. The welding distortion is removed by stopping the welding process and solidifying and shrinking the molten part while maintaining an inert gas atmosphere.

Effect> The back side of the welded part of the titanium member is heated in an inert gas atmosphere to partially melt it, then the heating is stopped, and the inside of the welded part is solidified while maintaining the inert gas atmosphere. Welding distortion is removed using shrinkage stress.

Embodiment An embodiment of the titanium material welding strain removal method according to the present invention will be described with reference to the drawings. Figure 1, Figure 2, Figure 3, Figure 4
FIG. 1 is a process explanatory diagram of an embodiment of the present invention.

Figure 1 shows a welded thick titanium structure. 1st
As shown in the figure, titanium profile 1 and titanium plate bracket 2
are welded along the joint corners A and B. When solid welds 3a and 3b are applied along the joints A and B of titanium parts within the thickness shown in Figure 1, in the case of titanium parts, when the molten titanium in the welds solidifies, it shrinks. This generates internal stress, which causes welding strain, and the titanium member 2 shown by the dotted line in FIG. 2 deforms as shown by the solid line.

The present invention provides a method for removing welding distortion generated in the welded portion of a titanium member within such thickness, and FIGS. 3 and 4 are explanatory diagrams of one embodiment thereof.

In the case shown in FIG. 3, a fillet weld 3b is applied along the joint corner B between a thick titanium bracket 2 and a titanium profile 1, and the bracket 2 is welded due to welding distortion at the joint corner B.
The dotted line portion is deformed as shown by the solid line. In the present invention, the back side surface layer 4 of the corner welded portion 3b of the bracket 2 is heated with an arc 6 of about 6000° C. of a TIG arc 5. The heated portion is shielded from the influence of air in an inert gas atmosphere such as argon gas, and the surface layer 4 directly under the arc 6 is melted.

Next, the TIG arc 5 is cut, and the inert gas atmosphere is maintained as it is to cool and solidify the molten portion. When the surface layer 4 of the bracket 2 cools and solidifies, the internal shrinkage stress generated by the solidified portion is used to remove welding distortion of the bracket 2, and the deformed bracket 2 as shown by the solid line is corrected to its original position as shown by the dotted line. Be able to do that. In addition, when removing welding distortion, the heated molten part must be protected with inert gas at 400℃ even for titanium materials.
This is to prevent oxides and nitrides from forming and increasing brittleness when exposed to the atmosphere.

Next, in FIG. 4, the deformation shown by the solid line due to the welding strain caused by the corner weld 3a of the titanium profile 1 welded along the joint corner A shown in FIG. FIG. 3 is an explanatory diagram illustrating a method for removing welding distortion according to the present invention.

As shown in FIG. 4, the arc 6 of the TIG arc 5 is used to heat the titanium profile 1 along the surface layer 8 on the back side of the corner weld 3a. The heated portion is shielded from the influence of air in an inert gas atmosphere such as arcon gas, and the surface layer 8 directly under the arc 6 is melted. Next, the TIG arc 5 is cut, the inert gas atmosphere is left as it is, and the molten portion is cooled and solidified. When the surface layer 8 of the titanium profile 1 is cooled and solidified, the solidified part uses the internal shrinkage stress generated during solidification to remove welding strain, and the titanium profile 1 deformed as shown by the solid line is returned to its original position as shown by the dotted line. can be corrected.

<Effects of the Invention> According to the method for removing welding strain on titanium materials according to the present invention, the surface layer on the back side of the welded portion where welding strain remains is heated and melted in an inert gas atmosphere, and then melted while maintaining the inert gas atmosphere. Welding distortion can now be easily removed by cooling and solidifying the part. In particular, titanium has a low thermal conductivity, making it difficult for local heating heat to be transferred, allowing for a large temperature difference between the front and back surfaces, which is highly effective in eliminating strain. Therefore, problems such as material cracking that occur when strain is removed by press pressing or gas burner heating as in the past do not occur. Therefore, it has become possible to weld titanium materials with high processing accuracy.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a welded titanium member structure, Fig. 2 is a side view showing deformation due to welding distortion of the structure shown in Fig. 1;
FIG. 3 is an explanatory diagram of an embodiment of the present invention of a portion shown in FIG. 2, and FIG. 4 is an explanatory diagram of an embodiment of the present invention of a portion other than that shown in FIG. 2. In the drawing, 1 is a titanium profile, 2 is a bracket, 3a, 3b
Self-welded parts, 4 and 8 are surface parts, 5 is TIG erso,
6 is an arc, and 7 is an inert gas atmosphere. Figure 1 Figure 3

Claims (1)

[Claims] The back side of the welded part of the titanium member with welding distortion is heated and melted in an inert gas atmosphere, then the heating is stopped and the molten part is solidified and shrunk while maintaining the inert gas atmosphere to remove the welding distortion. A titanium material welding strain removal method characterized by: