JPS6340687A - Dissimilar metal joined joint - Google Patents

Abstract

PURPOSE:To improve the joining strength of a joined joint of dissimilar metals and to maintain the safety of the joint by making an angle made by the member surface with the joining surface under a specific value at the time of welding the dissimilar metals of Zr alloy and stainless steel. CONSTITUTION:The members 1 and 2 to be joined are machine so that the joining angle of the members is made <45 deg. and the machined surfaces are cleaned and then, both the members 1 and 2 are fitted to each other. Next, these members are put in a stainless steel pipe 4 and the member 2 side to be joined is covered using a stainless disk 5. These members are subjected to the electron beam welding in a vacuum vessel and afterward, the joining surface 3 is spread and joined in a high temperature hydrostatically pressurized vessel. In this way, the strength of the joint can be maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a dissimilar material joining joint used in chemical plants, nuclear couplants, nuclear fuel reprocessing plants, etc.

[Conventional technology]

Friction welding and diffusion welding are generally applied in conventional joints for dissimilar materials of pipes and rods, but when Zr alloy and stainless steel are joined using these methods, the strength of the joint is If the tensile test is carried out at low tension, the joint will almost always break, so when applying it to structural members, design measures such as increasing the wall thickness of the joint were taken.

FIG. 5 shows a joint for joining dissimilar pipes using a conventional joining method. In FIG. 5, 01 is a material to be joined, such as stainless steel, 02 is another material to be joined, such as Zr or Zr alloy, and 05 is a joining surface. In the conventional dissimilar material joint shown in FIG. 5, the joint strength is weak, so the strength is compensated for by increasing the thickness of the joint.

[Problem that the invention seeks to solve]

The object of the present invention is to combine stainless steel with Zr or Zr.
In dissimilar metal joints that join alloys, we provide a complete range of dissimilar metal joints that increase the strength of the joint to the same level or higher than that of the base metal, and do not require any design adjustments when used as structural materials. It is to be.

[Means for solving problems]

The present invention provides Z
The present invention relates to a dissimilar material joining joint made of r or Zr alloy and stainless steel, which is characterized in that the angle between the member surface and the joining surface is less than 2456.

Hereinafter, the angle formed between the surface of the member and the bonding surface will be referred to as the bonding angle.

In addition, as a specific example of Zr alloy, pure Zr (ASTM
.

R60702) Zr-2,5Nb alloy (
(STM, R60705), Zr-1,5Sn alloy (STM, R160704), etc. can be used.

[Effect]

FIG. 4 is an explanatory diagram of normal stress and shear stress acting on the joint surface. In the figure, 1 and 2 are members to be joined, and 3
V! , the joint surface, X is the joint angle, and ψ is the angle between the perpendicular to the joint surface and the load direction. In addition, P is the load, and σ is the friendly stress generated in the member due to the load P, σ. is the stress acting in the vertical direction of the joint surface 5 at that time, and τ is the shear stress acting on the joint surface 5.

Now, σ generated by load P. and τ is denoted by σ,
It is represented by the following equations (1) and (2).

a n air a co? p≦'cri −・・−・i
l+τ −−sho ψ≦τ. 1□ ・・・・・・(
2+where, σ. 1. and τ. 1 is the breaking strength of the joint surface 3, and σ. If τ is greater than this value, the joint surface 3 will break, and if it is less than this value, it will not be broken.

Table 1 shows that the stress σ caused by the load P is 10 kg.
/ σ due to the difference in joining angle when llI2. and the value of τ are as follows. According to this, σ.

It can be seen that τ becomes smaller as the joining angle becomes smaller, and τ becomes maximum when the joining angle is 45°.

For this reason, it is desirable that the joining angle be as small as possible.

Table 1 Next, the dissimilar material joining joint of the present invention will be explained based on the drawings.

Figure 1 is an explanatory diagram of the manufacturing method of the dissimilar metal joint of the present invention using the high temperature isostatic pressing (HIP) method, and Figures 2 and 5 are dissimilar metal joints with a joint angle X of 45 degrees. FIG.

In Figures 1 to 3, 1 is a member to be joined, which is a stainless steel pipe or rod, and 2 is another member to be joined, which is Zr.
It also shows a Zr alloy tube or rod, and 5 shows the joint surface.

Further, 4 is a stainless steel pipe, 5 is a stainless steel disk, and 6 is an electron beam welded metal.

The manufacturing procedure of the dissimilar material joining joint according to the present invention will be explained using FIG.

First, using members 1 and 2 to be joined, the joining angle is 45
After machining the parts so that the temperature is less than 100°C and thoroughly cleaning the machined surfaces, the two pieces are fitted together. Next, attach these to the stainless steel pipe 4
The stainless steel disc 5 is used to cover the member 291 to be joined, and the lid is completely closed. This is subjected to electron beam welding in a vacuum container (not shown), and the members 1 and 2 to be joined are tightly sealed in the stainless steel pipe 4 using the electron beam weld metal 6. By this operation, the joint surface 5 can be kept in a highly clean vacuum.

After that, 4 tons of stainless steel pipe containing 1,20 members to be welded
- Placed in a pressure vessel subjected to high temperature isostatic pressure processing,
Heat to about 1000C at ~2000 atmospheres for about 1 hour. Then, the stainless steel pipe 4 is evenly pressurized, and the stainless steel pipe 4 and the stainless steel disk 5 are all passed through with a pressure of 1000 to 200
A pressure of 0 atmospheres is transmitted to the members 1 and 2 to be joined, and
By heating at a high temperature of about 1000C, the members 1 and 2 to be joined are diffusion-bonded at the joining surface 3. After the HIP treatment, the stainless steel tube 4 is taken out, the stainless steel tube 4 and the stainless steel disc 5 are removed by machining, and the members 1 and 2 to be joined are removed.
A hole is made in the center of the hole, and a joint for joining dissimilar materials as shown in FIGS. 2 and 5 is made.

The processing steps are summarized as follows.

Mountain Machining of joint surfaces of parts (2) Degreasing, cleaning, and assembly (electron beam welding of 31 skin materials (+ o” tall) (4)
High temperature isostatic pressing (HIP) (800CX 2
hr ) (5) Removal of skin material and pipe processing (6) Degreasing and cleaning! 71 8 Items In addition, in Fig. 5, a joint line 5 with a joint angle o'' is created at the center of the wall thickness of the pipe, and a joint line 5 that runs along the joint line 5 is shown.
' to stop the operation.

Table 2 shows Zr as the member to be joined 2 and member 1 to be joined.
The tensile strength and fracture location of SUS 504 L dissimilar joint pipe are shown below. The joining style is determined by the length of the region 5' as shown in FIG. In the case of comparative joints with large joint angles, most of the joints were broken, and as the joint angle became smaller, the tensile strength increased.

In the case of the dissimilar material joining joint of the present invention, the fractured part is all made of Zr.
On the base metal side, zr indicates the tensile strength of the base material and is approximately constant, indicating that the joint strength is equal to or greater than the base material in the axial direction of the pipe. There is.

Table 2 [Effects of the Invention] According to the present invention, the Zr alloy using the high-temperature isostatic pressing (HRP) method has a joint strength that is equal to or higher than that of the base metal. When used in plants, there is no need to take design considerations into account, and dissimilar metal joints can be used safely and at low cost.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the manufacturing method of the dissimilar material joining joint of the present invention,
2 and 5 are longitudinal cross-sectional views of the dissimilar material joining joint of the present invention. FIG. 4 is an explanatory diagram of the operation according to the present invention, and FIG. 5 is a longitudinal cross-sectional view of a conventional dissimilar material joining joint. Sub-Agents 1) Meifuku Agent Ryo Hagiwara − Sub-Agent Atsuo Anzai

Claims (1)

[Scope of Claims] A dissimilar metal joint made of Zr or Zr alloy and stainless steel joined by high-temperature isostatic pressing, characterized in that the angle between the member surface and the joint surface is less than 45°. A joint for joining dissimilar materials.