Friction stir welding dissimilar metal pipe joint for low-temperature container and low-temperature container

Abstract

The invention discloses a friction stir welding dissimilar metal pipe joint for a low-temperature container and the low-temperature container, and relates to the technical field of low-temperature container manufacturing. The friction stir welding dissimilar metal pipe joint for the low-temperature container comprises a first metal pipe and a second metal pipe, the thermal expansion coefficient of the first metal pipe is larger than that of the second metal pipe, the first metal pipe and the second metal pipe are connected through friction stir welding, and the first metal pipe is provided with a holding extension section. The second metal pipe is provided with a supporting extension section, the supporting extension section is inserted into the holding extension section, and the holding extension section applies holding force to the supporting extension section when the second metal pipe is contracted when cooled. The low-temperature container comprises a low-temperature container body and an external flange, and the low-temperature container body and the external flange are connected through the friction stir welding dissimilar metal pipe joint for the low-temperature container. The friction stir welding dissimilar metal pipe joint and the low-temperature container have the advantages of being high in connection strength, capable of avoiding cracking, good in sealing performance and high in applicability.

Description

Technical Field

[0001] The invention relates to the technical field of cryogenic container manufacturing, and in particular to a friction stir welding dissimilar metal pipe joint for a cryogenic container and a cryogenic container. Background Art

[0002] Cryogenic containers are widely used in the fields of shipping, aerospace, refrigeration equipment, etc., for storing and transporting cryogenic medium materials, such as liquefied natural gas, liquid oxygen, liquid nitrogen, liquid hydrogen, liquid helium and liquid fluorine. Considering the impact of low temperature environment on material properties, aluminum alloy materials are usually used as the tank body of cryogenic containers. Since aluminum alloy materials are prone to oxidation reactions, stainless steel structures and equipment still exist in the entire system where the cryogenic container exists, such as vacuum pipelines and vacuum valves, so it is necessary to connect the aluminum alloy structure with the stainless steel structure. However, since the hardness of aluminum alloy is lower than that of stainless steel, the direct screwing method is likely to result in poor sealing of the connection between the aluminum alloy flange and stainless steel, affecting the sealing performance of the system. Therefore, it is necessary to use dissimilar metal pipe joints to solve the above problems.

[0003] Among the existing dissimilar metal pipe joints, the ones with better application performance are explosion welding pipe joints and diffusion welding pipe joints. However, when the two existing pipe joints are used in low-temperature environments, due to the different thermal expansion coefficients of dissimilar metals, they are prone to cracking at the dissimilar metal interface and have poor sealing performance. In order to further solve the above problems, it is necessary to increase the wall thickness of the pipe joint. However, this method of increasing the wall thickness of the pipe joint is not only limited in preventing cracking and improving sealing performance, but also does not have the space and conditions to use thick-walled pipe joints in many low-temperature container application scenarios. In addition, when the low-temperature medium stored and transported by the low-temperature container is conductive, severe electrochemical corrosion is prone to occur at the steel-aluminum dissimilar metal interface, which not only affects the sealing performance, but also is extremely inconvenient to repair and has high maintenance costs. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a friction stir welding dissimilar metal pipe joint for cryogenic containers and a cryogenic container which has high connection strength, can avoid cracking, has good sealing performance and strong applicability.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions: A friction stir welding dissimilar metal pipe joint for a low-temperature container, comprising a first metal pipe and a second metal pipe, wherein the thermal expansion coefficient of the first metal pipe is greater than the thermal expansion coefficient of the second metal pipe, the first metal pipe and the second metal pipe are connected by friction stir welding, the first metal pipe is provided with a clamping extension section, the second metal pipe is provided with a supporting extension section, the supporting extension section is inserted in the clamping extension section, and the clamping extension section applies a clamping force to the supporting extension section when it contracts in the cold.

[0006] As a further improvement of the above technical solution: The clamping extension section is an annular boss extending axially along the outer wall of the first metal tube, and the supporting extension section is an annular boss extending axially along the inner wall of the second metal tube. The annular boss of the second metal tube is inserted into the inner ring of the annular boss of the first metal tube.

[0007] The clamping extension section is an annular frustum extending axially along the outer wall of the first metal tube, and the supporting extension section is an annular frustum extending axially along the inner wall of the second metal tube. The cone angles of the two annular frustums are equal, and the cone angles are self-locking angles. The annular frustum of the second metal tube is inserted into the inner ring of the annular frustum of the first metal tube.

[0008] The conical surfaces of the two annular frustums are in a corrugated surface structure that matches each other.

[0009] The clamping extension section is a plurality of concentric annular bosses extending axially along the end of the first metal tube, and the supporting extension section is a plurality of concentric annular bosses extending axially along the end of the second metal tube. The concentric annular bosses of the second metal tube are inserted into the concentric annular grooves between the concentric annular bosses of the first metal tube.

[0010] The concentric annular bosses are in a corrugated or straight tooth shape.

[0011] The welding seam between the first metal tube and the second metal tube presents a wave structure on the circumferential development surface.

[0012] An electrochemical corrosion protection component is provided between the first metal tube and the second metal tube.

[0013] The anti-electrochemical corrosion component is arranged in the first metal tube and the second metal tube, and is an isolation coating or an isolation gasket used to isolate the joint from the medium.

[0014] The anti-electrochemical corrosion component is arranged between the first metal tube and the second metal tube, and is an anti-electrochemical corrosion solder layer used to isolate the first metal tube and the second metal tube.

[0015] The electrochemical corrosion protection component is arranged outside the first metal tube and the second metal tube, and is a sacrificial anode used to change the potential relationship between the first metal tube and the second metal tube. The sacrificial anode is in direct contact with the first metal tube and the second metal tube at the same time.

[0016] A first clamp is fixed on the outer wall of the first metal tube, a second clamp is fixed on the outer wall of the second metal tube, one end of the sacrificial anode is pressed on the outer wall of the first metal tube by the first clamp, and the other end of the sacrificial anode is pressed on the outer wall of the second metal tube by the second clamp.

[0017] A clamp is provided on the outer wall of the welding joint between the first metal tube and the second metal tube, and the sacrificial anode is pressed onto the outer wall of the first metal tube and the second metal tube through the clamp.

[0018] The sacrificial anodes are provided with more than two pieces, and the more than two sacrificial anodes are distributed at intervals along the welding seam between the first metal tube and the second metal tube.

[0019] The first metal tube is an aluminum alloy tube, and the second metal tube is a steel tube.

[0020] An external flange is provided at the end of the second metal pipe.

[0021] A low-temperature container comprises a low-temperature container body, on which the above-mentioned friction stir welding dissimilar metal pipe joint for the low-temperature container is installed.

[0022] Compared with the prior art, the advantages of the present invention are: The friction stir welding dissimilar metal pipe joint for low-temperature containers of the present invention adopts friction stir welding connection, has higher connection strength, higher production efficiency and lower production cost; when used in a low-temperature environment, since the thermal expansion coefficient of the first metal pipe is greater than the thermal expansion coefficient of the second metal pipe, the shrinkage deformation of the first metal pipe after being cooled is greater than the shrinkage deformation of the second metal pipe, so that the clamping extension section can form a clamping force on the supporting extension section; at the same time, the supporting extension section forms a supporting effect on the clamping extension section, which limits the shrinkage deformation of the clamping extension section to a certain extent, so that the dissimilar metal pipe joint can reduce the deformation difference between the first metal pipe and the second metal pipe as a whole in the low-temperature environment, and further reduce the fission stress caused by the deformation difference at the welding joint, thereby avoiding cracking at the dissimilar metal interface and reduced sealing performance; the dissimilar metal pipe joint adopting this structure does not need to thicken the wall thickness of the pipe joint, and it is easier to be widely adapted to various application scenarios of low-temperature containers, and is no longer restricted by the spatial conditions of the application scenario.

[0023] The cryogenic container of the present invention includes all the technical features of the above-mentioned friction stir welding dissimilar metal pipe joint for cryogenic containers, and therefore has corresponding technical effects, which will not be described in detail herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0025] Figure 1 It is a schematic cross-sectional structure diagram of Example 1 of the dissimilar metal pipe joint of the present invention.

[0026] Figure 2 It is a schematic cross-sectional structure diagram of Example 2 of the dissimilar metal pipe joint of the present invention.

[0027] Figure 3 It is a schematic cross-sectional structure diagram of Example 3 of the dissimilar metal pipe joint of the present invention.

[0028] Figure 4 It is a schematic cross-sectional structure diagram of Example 4 of the dissimilar metal pipe joint of the present invention.

[0029] Figure 5 It is a schematic cross-sectional structure diagram of Example 5 of the dissimilar metal pipe joint of the present invention.

[0030] Figure 6 It is a schematic cross-sectional structure diagram of Example 6 of the dissimilar metal pipe joint of the present invention.

[0031] Figure 7 It is a schematic cross-sectional structure diagram of Example 7 of the dissimilar metal pipe joint of the present invention.

[0032] Figure 8 It is a schematic cross-sectional structure diagram of Example 8 of the dissimilar metal pipe joint of the present invention.

[0033] Fig. 9 It is a schematic diagram of the three-dimensional structure of Example 9 of the dissimilar metal pipe joint of the present invention.

[0034] Fig.10 It is a schematic diagram of the three-dimensional structure of Example 10 of the dissimilar metal pipe joint of the present invention.

[0035] Fig.11 It is a schematic structural diagram of a low-temperature container embodiment of the present invention.

[0036] The reference numerals in the accompanying drawings represent: 1. First metal tube; 11. Clamping extension section; 12. First clamp; 2. Second metal tube; 21. Supporting extension section; 22. Second clamp; 23. External flange; 3. Anti-electrochemical corrosion component; 31. Isolation coating; 32. Isolation gasket; 33. Anti-electrochemical corrosion solder layer; 34. Sacrificial anode; 4. Clamp; 5. Low-temperature container body. DETAILED DESCRIPTION

[0037] The embodiments of the present invention are described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0038] Dissimilar metal pipe joint embodiment 1: like Figure 1 As shown, the friction stir welding dissimilar metal pipe joint for cryogenic containers of this embodiment comprises a first metal pipe 1 and a second metal pipe 2, wherein the first metal pipe 1 is an aluminum alloy pipe and the second metal pipe 2 is a steel pipe. The thermal expansion coefficient of the first metal pipe 1 is greater than the thermal expansion coefficient of the second metal pipe 2, the first metal pipe 1 and the second metal pipe 2 are connected by friction stir welding, the first metal pipe 1 is provided with a clamping extension section 11, and the second metal pipe 2 is provided with a supporting extension section 21, the supporting extension section 21 is inserted in the clamping extension section 11, and the clamping extension section 11 applies a clamping force to the supporting extension section 21 when it contracts in cold. The friction stir welding dissimilar metal pipe joint for low-temperature containers of the present invention adopts friction stir welding connection, has higher connection strength, higher production efficiency and lower production cost; when used in a low-temperature environment, since the thermal expansion coefficient of the first metal tube 1 is greater than the thermal expansion coefficient of the second metal tube 2, the shrinkage deformation of the first metal tube 1 after being cooled is greater than the shrinkage deformation of the second metal tube 2, so that the clamping extension section 11 can form a clamping force on the supporting extension section 21; at the same time, the supporting extension section 21 forms a supporting effect on the clamping extension section 11, which limits the shrinkage deformation of the clamping extension section 11 to a certain extent, so that the dissimilar metal pipe joint can reduce the deformation difference between the first metal tube 1 and the second metal tube 2 as a whole in a low-temperature environment, and further reduce the fission stress caused by the deformation difference at the welding joint, thereby avoiding cracking at the dissimilar metal interface and reduced sealing performance; the dissimilar metal pipe joint adopting this structure does not need to thicken the wall thickness of the pipe joint, and it is easier to be widely adapted to various application scenarios of low-temperature containers, and is no longer limited by the spatial conditions of the application scenario.

[0039] In this embodiment, the clamping extension section 11 is an annular boss extending axially along the outer wall of the first metal tube 1, and the supporting extension section 21 is an annular boss extending axially along the inner wall of the second metal tube 2. The annular boss of the second metal tube 2 is inserted into the inner ring of the annular boss of the first metal tube 1.

[0040] In this embodiment, an anti-electrochemical corrosion component 3 is provided between the first metal tube 1 and the second metal tube 2. The anti-electrochemical corrosion component 3 is an anti-electrochemical corrosion solder layer 33 provided between the first metal tube 1 and the second metal tube 2. The anti-electrochemical corrosion solder layer 33 is used to isolate the first metal tube 1 from the second metal tube 2. Under the isolation effect of the anti-electrochemical corrosion solder layer 33, the electrochemical corrosion effect between the first metal tube 1 and the second metal tube 2 is suppressed, and the service life of the dissimilar metal pipe joint can be extended.

[0041] Dissimilar metal pipe joint embodiment 2: like Figure 2 As shown, this embodiment is basically the same as the dissimilar metal pipe joint embodiment 1, the only difference is that the anti-electrochemical corrosion component 3 also includes an isolation coating 31 provided in the first metal pipe 1 and the second metal pipe 2, and the isolation coating 31 is used to isolate the joint from the medium, thereby further playing a role in suppressing the electrochemical corrosion effect between the first metal pipe 1 and the second metal pipe 2.

[0042] Dissimilar metal pipe joint embodiment 3: like Figure 3 As shown, this embodiment is basically the same as the embodiment 1 of the heterogeneous metal pipe joint, and the only difference is that the holding extension section 11 is an annular frustum extending axially along the outer wall of the first metal pipe 1, and the supporting extension section 21 is an annular frustum extending axially along the inner wall of the second metal pipe 2. The cone angles of the two annular frustums are equal, and the cone angles are self-locking angles. The annular frustum of the second metal pipe 2 is plugged into the inner ring of the annular frustum of the first metal pipe 1. The annular frustum structure is used to facilitate the docking of the first metal pipe 1 and the second metal pipe 2. The cone angle is set as the self-locking angle, which can ensure that the connection between the first metal pipe 1 and the second metal pipe 2 is more reliable, and the holding extension section 11 exerts a holding force on the supporting extension section 21 when it is cold and shrinks, which can also be protected by the self-locking angle, so that the two have a tighter connection relationship when they are cold and shrink.

[0043] Dissimilar metal pipe joint embodiment 4: like Figure 4 As shown, this embodiment is basically the same as the dissimilar metal pipe joint embodiment 3, the only difference is that the anti-electrochemical corrosion component 3 also includes an isolation gasket 32 ​​provided in the first metal pipe 1 and the second metal pipe 2, and the isolation gasket 32 ​​is used to isolate the joint from the medium, thereby further playing a role in suppressing the electrochemical corrosion effect between the first metal pipe 1 and the second metal pipe 2. The isolation gasket 32 ​​is embedded in the grooves of the inner walls of the first metal pipe 1 and the second metal pipe 2, and the end of the second metal pipe 2 is provided with a connecting flange 23.

[0044] Dissimilar metal pipe joint embodiment 5: like Figure 5As shown, this embodiment is basically the same as the dissimilar metal pipe joint embodiment 3, and the only difference is that the conical surfaces of the two annular cones are corrugated surface structures that match each other. The use of the corrugated surface structure can further enhance the connection strength between the first metal tube 1 and the second metal tube 2, while also being able to maintain the clamping force exerted by the clamping extension section 11 on the supporting extension section 21 when it shrinks in the cold.

[0045] Dissimilar metal pipe joint embodiment 6: like Figure 6 As shown, this embodiment is basically the same as the dissimilar metal pipe joint embodiment 1, the only difference is that the holding extension section 11 is a multi-circle concentric annular boss extending axially along the end of the first metal pipe 1, the supporting extension section 21 is a multi-circle concentric annular boss extending axially along the end of the second metal pipe 2, and the concentric annular boss of the second metal pipe 2 is inserted into the concentric annular groove between the concentric annular bosses of the first metal pipe 1, and the concentric annular boss is in the shape of straight teeth. By setting the structure of the concentric annular boss, the shrinkage deformation can be effectively dispersed, the influence of shrinkage on the weld can be reduced, and the strength of the welding connection after being cooled can be ensured.

[0046] Dissimilar metal pipe joint embodiment 7: like Figure 7 As shown, this embodiment is basically the same as the dissimilar metal pipe joint embodiment 6, the only difference is that the concentric annular boss is corrugated. The use of this structure can reduce the local stress concentration of the concentric annular boss, so that the stress generated by the shrinkage deformation after cooling is more evenly dispersed.

[0047] Dissimilar metal pipe joint embodiment 8: like Figure 8 As shown, this embodiment is basically the same as the dissimilar metal pipe joint embodiment 1, and the only difference is that the welding seam between the first metal pipe 1 and the second metal pipe 2 is a wavy structure on the circumferential development surface. By adopting this structure, the torsional strength of the welding seam in the axial and circumferential directions can be improved by extending the length of the welding seam.

[0048] Dissimilar metal pipe joint embodiment 9: like Fig. 9 As shown, this embodiment is basically the same as the dissimilar metal pipe joint embodiment 1, the only difference is that the anti-electrochemical corrosion component 3 is arranged outside the first metal pipe 1 and the second metal pipe 2, and is a sacrificial anode 34 used to change the potential relationship between the first metal pipe 1 and the second metal pipe 2. The sacrificial anode 34 is in direct contact with the first metal pipe 1 and the second metal pipe 2 at the same time. In this embodiment, a zinc rod is used as the sacrificial anode 34. When the potential difference is generated, the sacrificial anode 34 will be electrochemically corroded first, and the later maintenance only needs to replace the electrochemically corroded sacrificial anode 34, which greatly reduces the maintenance cost.

[0049] In this embodiment, a first clamp 12 is fixedly provided on the outer wall of the first metal tube 1, and a second clamp 22 is fixedly provided on the outer wall of the second metal tube 2. One end of the sacrificial anode 34 is pressed onto the outer wall of the first metal tube 1 by the first clamp 12, and the other end of the sacrificial anode 34 is pressed onto the outer wall of the second metal tube 2 by the second clamp 22. This structure facilitates the installation and replacement of the sacrificial anode 34.

[0050] Dissimilar metal pipe joint embodiment 10: like Fig.10 As shown, this embodiment is basically the same as the dissimilar metal pipe joint embodiment 9, the only difference is that a clamp 4 is provided on the outer wall of the welding seam of the first metal tube 1 and the second metal tube 2, and the sacrificial anode 34 is pressed on the outer wall of the first metal tube 1 and the second metal tube 2 through the clamp 4. In other embodiments, more than two sacrificial anodes 34 can be provided, and the more than two sacrificial anodes 34 are distributed at intervals along the welding seam of the first metal tube 1 and the second metal tube 2. With the structure of this embodiment, the number and position of the sacrificial anodes 34 can be arbitrarily adjusted according to the needs of various application scenarios, so that the role of the sacrificial anodes 34 can be more accurately and fully exerted.

[0051] Cryogenic container embodiment: like Fig.11 As shown, the cryogenic container embodiment of the present invention comprises a cryogenic container body 5, on which is mounted the friction stir welding dissimilar metal pipe joint for the cryogenic container as described in Example 4. The cryogenic container of the present invention includes all the technical features of the friction stir welding dissimilar metal pipe joint for the cryogenic container, and thus has corresponding technical effects, which will not be described in detail herein.

[0052] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the technical content disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention should fall within the scope of protection of the technical solution of the present invention.

Claims

1. A friction stir welding dissimilar metal pipe joint for a cryogenic container, comprising a first metal pipe (1) and a second metal pipe (2), wherein the thermal expansion coefficient of the first metal pipe (1) is greater than the thermal expansion coefficient of the second metal pipe (2), and characterized in that: The first metal tube (1) and the second metal tube (2) are connected by stir friction welding; the first metal tube (1) is provided with a clamping extension section (11); the second metal tube (2) is provided with a supporting extension section (21); the supporting extension section (21) is inserted into the clamping extension section (11); when the clamping extension section (11) contracts when exposed to cold, the clamping extension section (11) applies a clamping force to the supporting extension section (21).

2. The friction stir welding dissimilar metal pipe joint for cryogenic containers according to claim 1, characterized in that: The clamping extension section (11) is an annular boss extending axially along the outer wall of the first metal tube (1), and the supporting extension section (21) is an annular boss extending axially along the inner wall of the second metal tube (2). The annular boss of the second metal tube (2) is plugged into the inner ring of the annular boss of the first metal tube (1).

3. The friction stir welding dissimilar metal pipe joint for cryogenic containers according to claim 1, characterized in that: The clamping extension section (11) is an annular cone extending axially along the outer wall of the first metal tube (1), and the supporting extension section (21) is an annular cone extending axially along the inner wall of the second metal tube (2). The cone angles of the two annular cones are equal, and the cone angles are self-locking angles. The annular cone of the second metal tube (2) is inserted into the inner ring of the annular cone of the first metal tube (1).

4. The friction stir welding dissimilar metal pipe joint for cryogenic containers according to claim 3, characterized in that: The conical surfaces of the two annular frustums are in a corrugated surface structure that matches each other.

5. The friction stir welding dissimilar metal pipe joint for cryogenic containers according to claim 1, characterized in that: The clamping extension section (11) is a plurality of concentric annular bosses extending axially along the end of the first metal tube (1), and the supporting extension section (21) is a plurality of concentric annular bosses extending axially along the end of the second metal tube (2), the concentric annular bosses of the second metal tube (2) being inserted into the concentric annular grooves between the concentric annular bosses of the first metal tube (1).

6. The friction stir welding dissimilar metal pipe joint for cryogenic containers according to claim 5, characterized in that: The concentric annular bosses are in a corrugated or straight tooth shape.

7. The friction stir welding dissimilar metal pipe joint for a cryogenic container according to any one of claims 1 to 6, characterized in that: The welding seam between the first metal tube (1) and the second metal tube (2) presents a wave structure on the circumferential development surface.

8. The friction stir welding dissimilar metal pipe joint for a cryogenic container according to any one of claims 1 to 6, characterized in that: An electrochemical corrosion prevention component (3) is provided between the first metal tube (1) and the second metal tube (2).

9. The friction stir welding dissimilar metal pipe joint for cryogenic containers according to claim 8, characterized in that: The anti-electrochemical corrosion component (3) is arranged in the first metal tube (1) and the second metal tube (2), and is an isolation coating (31) or an isolation gasket (32) used to isolate the joint from the medium.

10. The friction stir welding dissimilar metal pipe joint for cryogenic containers according to claim 8, characterized in that: The anti-electrochemical corrosion component (3) is arranged between the first metal tube (1) and the second metal tube (2), and is an anti-electrochemical corrosion solder layer (33) used to isolate the first metal tube (1) and the second metal tube (2).

11. The friction stir welding dissimilar metal pipe joint for cryogenic containers according to claim 8, characterized in that: The anti-electrochemical corrosion component (3) is arranged outside the first metal tube (1) and the second metal tube (2), and is a sacrificial anode (34) used to change the potential relationship between the first metal tube (1) and the second metal tube (2). The sacrificial anode (34) is in direct contact with the first metal tube (1) and the second metal tube (2) at the same time.

12. The friction stir welding dissimilar metal pipe joint for cryogenic containers according to claim 11, characterized in that: A first clamp (12) is fixedly provided on the outer wall of the first metal tube (1), a second clamp (22) is fixedly provided on the outer wall of the second metal tube (2), one end of the sacrificial anode (34) is pressed onto the outer wall of the first metal tube (1) through the first clamp (12), and the other end of the sacrificial anode (34) is pressed onto the outer wall of the second metal tube (2) through the second clamp (22).

13. The friction stir welding dissimilar metal pipe joint for cryogenic containers according to claim 11, characterized in that: A clamp (4) is provided on the outer wall of the welding seam between the first metal tube (1) and the second metal tube (2), and the sacrificial anode (34) is pressed onto the outer wall of the first metal tube (1) and the second metal tube (2) through the clamp (4).

14. The friction stir welding dissimilar metal pipe joint for cryogenic containers according to claim 13, characterized in that: The sacrificial anodes (34) are provided with more than two pieces, and the more than two sacrificial anodes (34) are distributed at intervals along the welding seam of the first metal tube (1) and the second metal tube (2).

15. The friction stir welding dissimilar metal pipe joint for a cryogenic container according to any one of claims 1 to 6, characterized in that: The first metal tube (1) is an aluminum alloy tube, and the second metal tube (2) is a steel tube.

16. The friction stir welding dissimilar metal pipe joint for cryogenic containers according to claim 15, characterized in that: An external flange (23) is provided at the end of the second metal tube (2).

17. A cryogenic container, comprising a cryogenic container body (5), characterized in that: The cryogenic container body (5) is provided with a friction stir welding dissimilar metal pipe joint for a cryogenic container as claimed in any one of claims 1 to 16.

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