JP2003305586A - Bonded joint consisting of different kind of metallic material and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lap joint which consists of different kinds of metallic materials and has high bond strength, and whose end part has corrosion resistance, and to provide a manufacturing method for the lap joint. <P>SOLUTION: In a lap bonded joint consisting of different kinds of metallic materials, where a lapping material 3 is lapped over a base material 4, the bonded part of the joint consists of a part 6 formed by a friction stir welding method and a part 8 formed around the part 6 by a brazing method. Extending the brazed part to the end part of the lapping material is, in particular, more effective, and making the joint by lapping titanium over a steel material is effective. The joint is manufactured by inserting a brazing agent into the whole part or one part of the interface between the base material and the lapping material, friction stir bonding them, and simultaneously brazing them using the heat generated at the time of bonding. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonded joint made of different metal materials and a method for manufacturing the same.
More specifically, the present invention relates to a dissimilar metal joint that is joined by friction stir welding and a method for manufacturing the joint.

[0002]

Various steel materials such as carbon steel, alloy steel, stainless steel, heat resistant steel, Ni, Ni alloy, Co, Co alloy, Al, Al alloy, Ti, Ti alloy, Cu, Cu alloy, Mg, Mg. To date, various metal materials such as alloys have been developed as structural materials and applied to various structures and mechanical equipment. In recent years, in particular, in order to fully utilize the individual functions of these metal materials, many structures and mechanical parts in which these various metal materials are complicatedly combined have been developed.

In a product in which such dissimilar metal materials are combined, it is necessary to appropriately join the dissimilar metal materials. However, in the fusion welding method such as arc welding method which is widely used industrially, the dissimilar metal materials are mainly composed. In many cases, brittle intermetallic compounds composed of elements continuously appear at the joint interface, and generally exhibit a coarse solidified structure, so that the joint strength becomes weak.

Therefore, in order to join dissimilar metal materials,
Solid phase joining methods such as friction joining and diffusion joining that do not form a molten phase have been developed, but the former can only be applied to small parts, and the latter has problems such as long-term heat treatment. However, it has not been widely used industrially.

By the way, in recent years, a new joining method called a friction stir welding method has been developed, and has been widely used mainly for joining the same or similar metal materials. Although this friction stir welding is a solid-phase welding method, it is significantly more efficient than the conventional solid-state welding method, has a welding efficiency equal to or higher than that of the fusion welding method, and has few welding defects. In addition, it has the advantage that the metal structure of the joint is refined by recrystallization and the improvement of mechanical properties can be expected. Furthermore, it can be applied to large parts and structures, especially Al and its alloys. It has been applied to the joining of, and has come to be used in the manufacture of rail car outer panels and the like. Further, recently, its application has been advanced to steel materials and titanium materials.

Since this method is basically solid phase bonding, it is considered that it can be applied to bonding between dissimilar metals. That is, a cylindrical rotor composed of a disk 2 and a pin 1 as shown in FIGS. 1 (a), (b) and (c) is used as a welding tool, and this welding tool is placed on a base material 4. It is inserted into the article to be joined (bonding material) 3 and rotated while pressing it with the disk 2 to generate frictional heat to soften the material and to stir the metal material around the pin 1 slightly beyond the bonding interface. Then, the metals on both sides are joined 6 together. Then, by moving this welding tool in the direction of arrow 7, the base material 3 and the joining material 4 at the passage portion are welded.

However, the joints made of dissimilar metals joined by such a method do not necessarily have a large joint area, and in order to obtain sufficient joint strength, a plurality of unjoined portions adjacent to the joints are successively formed. It was necessary to perform the joining process once and take measures such as increasing the joining area. In addition, there is a gap between the joint and the end of the mating material, and this acts as a notch to make it impossible to sufficiently enhance the joint strength. Depending on the situation, there is a risk that corrosion will progress.

[0008]

In view of such a situation, the present invention makes it possible to manufacture the joint portion between the base material and the laminated material by friction stir welding with one pass or a small number of passes, and to obtain sufficient joint strength. Provided is a lap-joint joint made of dissimilar metal materials, and a method for manufacturing the same. Particularly, for a metal material in which corrosion resistance is important, a lap-joint joint that suppresses the progress of corrosion in the gap between dissimilar metals and The manufacturing method is provided.

[0009]

DISCLOSURE OF THE INVENTION The inventors of the present invention have made extensive studies to apply friction stir welding to joining dissimilar metal materials, and as a result, have decided to use a brazing filler metal in a gap formed between dissimilar metals. Focusing attention, the heat generated in the friction stir welding is higher than the heating temperature required for brazing the different metal materials by appropriately selecting the brazing filler metal, and the friction stir welding and brazing can be performed at the same time. I found a thing.

The present invention has been completed based on the results of applying such knowledge and further studying the bonding state in detail, and the gist thereof is as follows. (1) In a lap-joint joint formed by superposing a base material and a laminated material made of a metal material different from the base material, a joint portion is formed by a friction stir welding method and a peripheral portion thereof is formed by a brazing method. A joint made of dissimilar metal materials. (2) The joint according to (1) above, wherein the brazing portion is from the end portion of the friction stir welding portion to the end portion of the laminated material. (3) The joint joint made of a dissimilar metal material as described in (1) or (2) above, wherein the base material is a steel material and the laminated material is titanium. (4) A method for manufacturing the bonded joint according to any one of (1) to (3) above, wherein a brazing material is provided at all or a part of the interface between the superposed base material and the laminated material. A method for manufacturing a joined joint made of a dissimilar metal material, which comprises inserting and friction stir welding, and at the same time brazing by the heat generated again.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. First, in the present invention (1), in a lap joint made of a different metal material, in which a base material and a laminated material made of a metal material different from the base material are overlapped, the joint portion is formed by a friction stir welding method. It is decided to consist of the part and the part by the brazing method. In such a jointed joint, the brazing portion supplements the joint strength of the joint, so that the joint strength is higher than that of a joint including only a friction stir welded portion having a small joint area.

Further, in the case of joining only by friction stir welding,
As shown in FIG. 2 (b), the end portion of the welded portion has a notch shape with an acute angle, but in the present invention, as shown in FIG. 3 (b), in the portion adjacent to the end portion of the friction stir welded portion. Since the brazing filler metal 8 once melted is solidified so that its end portion becomes an arc shape, the notch-shaped gap is eliminated, cracking of the joint portion is suppressed, and the joint area is increased by brazing or more. The bonding strength is improved. Here, the brazing part may be on both sides of the friction stir welding part, or may be only one. It is expected that the joint strength will be higher when both sides are brazed, but the effect of the present invention can be achieved even if only one side is brazed.

In the present invention (1), as shown in FIG. 3 (c), the present invention (2) is particularly the case where the brazing portion extends to the end of the lap material. In this case, the present invention (1) ), That is, the two effects of increasing the joint area and preventing the formation of a notch-shaped gap are achieved, it is of course possible to obtain a dissimilar metal joint having high joint strength. Since the gap between the dissimilar metals is completely filled in, the stress concentration on this portion is relaxed and the joint strength is further improved. In addition, there is an advantage that moisture and the like can be suppressed from entering the gap and deterioration of the joint due to corrosion can be suppressed.

In the present invention (3), in the invention (1) or (2), the base material is a steel material and the laminating material is titanium. Titanium is a material having extremely high corrosion resistance, and by joining it to a steel material, it can be expected to protect the steel material from a corrosive environment for a long period of time. Therefore, it is preferable to have higher bonding strength in order to use it for a long term with peace of mind. Therefore, the present invention (3) is a combination of materials that can particularly exert the effects of the present invention. In particular, when the present invention (2) is applied and the brazing filler metal is filled up to the end of titanium (laminated material), the gap is completely filled, so that infiltration of moisture and the like is suppressed and the high anticorrosion effect of titanium is exerted more and more. become able to.

The lap joint of dissimilar metals having high joint strength and excellent corrosion resistance as described above is
For example, it can be produced by the method described in the present invention (4). That is, the brazing filler metal is inserted into all or part of the interface between the superposed base metal and the laminated base material, friction stir welding is performed, and at the same time, brazing is performed by the heat generated at that time. Here, the tools for friction stir welding (1 and 2 in FIG. 1) are basically inserted into a mating material to generate friction heat, and if a brazing material that melts by this heat is appropriately selected, The effects of the present invention are sufficiently achieved.

For example, the temperature during friction stir welding is 600 ° C.
When the front and rear Al alloys are composite materials, A with a lower melting point
When 1-12 mass% Si or the like is used as a brazing material, it can be joined to steel or the like and the effect of the present invention can be exhibited. Alternatively, Sn—Zn alloy known as soft solder (solder) has a lower melting point and is convenient for joining Al and dissimilar metals. In addition, the temperature when friction stir welding titanium is about 90
When the temperature is 0 ° C. and a brazing material having a melting point lower than that of silver or copper is used, it can be bonded to a base material such as steel and the effect of the present invention can be obtained. Further, a pure metal having a relatively low melting point such as Sn is also suitable as the brazing material.

Here, when trying to braze to the end of the joining material, heat from the friction stir welding reaches the end and the brazing material is melted also at the end so that the brazing material is melted from the end. It is necessary to properly adjust the insertion position of the tool.

When the present method is applied, the flux may or may not be used, and it may be appropriately determined depending on the wettability of the laminating material and the base material, and the present invention does not define this. Further, the shield with an inert gas or the like may be appropriately determined according to the characteristics of the material, and the present invention does not specify this. However, it is preferable to shield when an active metal such as Ti is bonded or when no flux is used.

[0019]

EXAMPLES The effects of the present invention will be described in more detail based on examples. (Experiment 1) A base material (plate) having a thickness of 5 mm and a thickness of 1.5 mm
Of the laminated material (plate) are overlapped with each other, and at a position of 15 to 18 mm measured from the end portion of the laminated material, a width of 3 mm and a thickness of 0.
Insert the brazing material of 05mm, 22mm from the end of the mating material
At this position, the friction stir welding tool was inserted to a depth near the interface between the mating material and the base metal, and friction stir welding was performed. Flux was used in Test Nos. 1 to 5, and no other flux was used. For comparison, some samples were friction stir welded without inserting a brazing filler metal.

A test piece having a width of 30 mm was cut out from this sample, and as shown in FIG. 4, the base material was fixed with bolts 10, and the mating material on the non-bonded portion side was slightly lifted upward and pulled in the direction of arrow 9 The peel strength of the joint was measured, and this was defined as the joint strength. Table 1 shows the types of base material, laminated material, and brazing material, and the measured bonding strength.

In Table 1, test numbers 2, 3, 5, 7,
Reference numerals 8, 9, 10, and 12 are examples of the inventions (1) to (3), and are joints manufactured by the method described in the invention (4). All of them are made of the same combination of the base material and the laminated material, and are manufactured under exactly the same friction stir welding conditions, and the joining strength is higher than that of the comparative example in which the joining is achieved only by the friction stir welding portion.

That is, the test numbers 2 and 3 are compared with the test number 1, the test number 5 is compared with the test number 4, and the test numbers 7 to 1 are compared.
No. 0 has a higher bonding strength than Test No. 6 and Test No. 12 has a higher bonding strength than Test No. 11, and the effects of the present invention are sufficiently exhibited. Since this has a brazing part in addition to the friction stir welding part, the joining area is increasing, and the notch-shaped gap is blunted into an arc shape by brazing, and cracking of the joining part is suppressed. It is due to the fact.

[0023]

[Table 1]

(Experiment 2) A base material (plate) having a thickness of 5 mm was laminated with a laminated material (plate) having a thickness of 1.5 mm, and in the meantime, at a position of 0 to 5 mm measured from the end of the laminated material, A brazing filler metal having a width of 5 mm and a thickness of 0.07 mm was inserted, and a friction stir welding tool was inserted at a position 10 mm from the end of the joint material to a depth near the interface between the joint material and the base metal to perform friction stir welding. .
Flux was used in Test Nos. 13 to 14, and no other flux was used.

A test piece having a width of 30 mm was cut out from this sample, and as shown in FIG. 4, after fixing the base material, while pulling the unbonded part side joining material slightly upward, pulling it in the direction of arrow 9 to join it. Peel strength was measured and this was defined as the bonding strength. Table 2 shows the types of base material, laminated material, and brazing material, and the measured bonding strength.

As shown in Table 2, all the test numbers were manufactured under the same friction stir welding conditions with the same combination of the base metal and the laminated material, and the welding was achieved only by the friction stir welding. The bonding strength is higher than that of the comparative example described. That is, the test number 13 has a higher bonding strength than the test number 1, the test number 14 has a higher bonding strength than the test number 4, and the test numbers 15 to 17 have a higher bonding strength than the test number 6, and the effect of the present invention is sufficient. Has been demonstrated. Since this has a brazing part in addition to the friction stir welding part, the joining area is increasing, and the notch-shaped gap is blunted into an arc shape by brazing, and cracking of the joining part is suppressed. It is due to the fact.

Further, in the examples shown in Table 2, the brazing part extends from the friction stir welding part to the end of the laminated material,
Since the stress concentration on this portion is also alleviated, the joint strength is improved compared to the case where the gap is not completely filled with the brazing material. That is, test number 13 is test number 2
Compared with test number 5, test number 14 is compared with test number 1
Nos. 5 and 16 have improved joint strength as compared with Test Nos. 9 and 10, respectively.

[0028]

[Table 2]

(Experiment 3) 10% NaCl aqueous solution was sprayed in the vicinity of the end of the laminated material of the samples cut out from the sample numbers 1, 13, 6, 10, 16, 17 prepared in Experiment 1 and Experiment 2 and after 2 weeks. The state of corrosion of the base metal near the interface of was investigated by cross-section observation. The results are shown in Table 3. In Table 3, test numbers 13, 10, and 1 which are examples of the present invention
Nos. 6 and 17 have a combination of the same base material and a laminated material, are manufactured under exactly the same friction stir welding conditions, and have a deeper corrosion depth than the comparative example in which welding is achieved only by the friction stir welding portion. It becomes smaller, and the anticorrosion effect at the edge of the laminated material appears.

That is, the test number 13 is smaller than the test number 1, and the test numbers 10, 16 and 17 are smaller in the corrosion depth than the test number 6. This is because, in the present invention, the intrusion of water or the like into the gap is suppressed, and the deterioration of the joint due to corrosion is suppressed. Especially test number 1
In Nos. 3, 16 and 17, since the gap is completely filled with the brazing material, the invasion of the aqueous solution is completely prevented. This effect is particularly remarkable when titanium having high corrosion resistance is a laminated material. That is, in Test Nos. 16 and 17 in which the gap was completely filled, no progress of corrosion was observed under the test conditions.

[0031]

[Table 3]

[0032]

As described above, according to the present invention, by arranging the joint portion by the brazing method around the joint portion by the friction stir welding method, high joint strength and excellent corrosion resistance can be obtained. It is possible to provide a lap joint made of different kinds of metal materials, and a method for manufacturing the same. In particular, for corrosion protection of steel materials, in a dissimilar material joint using a highly corrosion-resistant titanium material as a joining material, it is possible to exert a high effect on strong joining and corrosion prevention near the edges of the joining material. The industrial value is extremely high.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an example of an embodiment of lap welding by friction stir welding, in which (a) is a sectional view of a welding tool,
(B) is sectional drawing which shows the condition at the time of joining, (c) is the top view.

2A and 2B are diagrams schematically illustrating an embodiment in which lap joining is performed by friction stir welding without using a brazing material, FIG. 2A is a cross-sectional view, and FIG. 2B is the inside of a frame of FIG. It is the figure which expanded and displayed.

FIG. 3 is a diagram schematically showing an example of an embodiment of the present invention, in which (a) is a cross-sectional view when a brazing material is inserted in a portion adjacent to a friction stir welding part, and (b) is (a). It is the figure which expanded and displayed the inside of the frame. Further, (c) is an enlarged display view in the case where the brazing portion extends to the end of the laminated material.

FIG. 4 is a diagram showing a peel test method for evaluating the bonding strength.

[Explanation of symbols]

1: Pin of welding tool 2: Disc of welding tool 3: Metal material to be joined (laminating material) 4: Metal material to be joined (base material) 5: stirring area 6: Friction stir joint 7: Joining direction 8: Brazing joint 9: Load direction of peel test 10: Test piece fixing bolt

Claims (4)

[Claims] 1. A lap-joint joint formed by superposing a base material and a laminated material made of a metal material different from the base material, wherein a joint portion is formed by a friction stir welding method and a brazing method around the portion. And a part consisting of
Joined joint made of dissimilar metal materials. 2. The joint according to claim 1, wherein the brazing portion is from the end portion of the friction stir welding portion to the end portion of the laminated material. 3. The joint according to claim 1 or 2, wherein the base material is a steel material and the laminated material is titanium. 4. A method for manufacturing the bonded joint according to any one of claims 1 to 3, wherein a brazing filler metal is inserted into all or part of the interface between the superposed base metal and the laminated base metal. A method for producing a bonded joint made of different kinds of metal materials, which comprises simultaneously performing friction stir welding and brazing by heat generated at that time.