JP2746066B2 - Diffusion bonding method of tube rod - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to steel bars used for the construction of concrete buildings, steel pipes used for various pipes, and the like .
TECHNICAL FIELD The present invention relates to a method for diffusion joining of a tube rod used for butt joining .

[0002]

2. Description of the Related Art In the construction of large concrete buildings such as bridge piers, construction is carried out while adding a large number of reinforcing bars. Therefore, it is very important to efficiently join the reinforcing bars in order to shorten the construction period.

[0003] Conventionally, gas pressure welding has been mainly used for joining these reinforcing bars. This joining method is a method in which rebars are butted, the butted portion is sufficiently heated with a reducing flame of a gas burner, and then upset is applied by hydraulic pressure to finish the butted portion into a shape having a sufficient swelling.

However, in the conventional joining by gas pressure welding,
Most of the process was done manually and was very inefficient. In addition, there is a problem that the operation requires skill and the quality of the joint is not stable.

In order to solve such a problem, insert materials having a melting point lower than that of the base material are sandwiched between the joining surfaces, and the base materials are butted against each other. Liquid phase diffusion bonding, which is heated to a temperature equal to or higher than the melting point, has been introduced into the joining of reinforcing bars (Japanese Patent Laid-Open No. 2-754)
No. 78, JP-A-2-241677, JP-A-3
-230874, JP-A-4-757334-6).

[0006] In this method, the melting point of the insert material gradually increases due to the diffusion of the melting point lowering element contained in the insert material into the base material during heating, and the joining is finally completed by isothermal solidification. Therefore, there is an advantage that the joining can be completed at once even for a large area joint such as a reinforcing bar joint.

However, in this method, handling of the insert material becomes a problem. That is, the insert material used for the liquid phase diffusion bonding is a thin foil body, and it takes time and effort to handle the insert material, or the insert material may not be inserted into the butt portion, or until the insert material is completely inserted into the butt portion. If the insert material falls off during the process, there is a risk that the joining is performed without the insert material. Once the joining is performed, it is difficult to determine the presence or absence of the insert material after the joining, so that there is a possibility that poor joining quality may occur due to forgetting to insert or dropping out the insert material.

[0008] Further, in this method, it is necessary to cause a wetting phenomenon between the surface and the joint surface with the insert material. That is,
When the insert material melted during the joining process causes poor wetting of the joining surface, the portion becomes a joining defect, which causes deterioration of the joint performance. However, due to the wrinkles of the insert material and the roughness of the joint surface, there is a high risk of poor wetting,
This is also a major problem with the use of insert materials.

In order to solve the problem associated with the use of the insert material, Japanese Patent Application Laid-Open No. 4-7573-4 discloses that at least a part of the joint surface of a pair of strips to be joined is covered. The use of an insert material having a protrusion protruding outward from the joining surface, and a retaining member that engages with at least one of a pair of strips to be joined and holds the insert material on the joining surface around the insert material It is disclosed that before a pair of strips to be joined are abutted, an insert material is previously fixed to a joining surface of one of the strips by bonding, adhesion, spot welding or magnetic adhesion.

[0010]

However, these countermeasures have the following problems.

In the case of an insert material having projections, the presence of the insert material after joining can be determined by the projections being sagged after joining and remaining outside the joint.
However, as long as the insert material is a foil, the problems of handleability and poor wetting cannot be solved.

As a countermeasure for providing a holding member around the insert material, when the holding member is integrated with the insert material,
Since the insert material has no strength, a sufficient holding function cannot be obtained, and when the holding member is a member different from the insert material,
Even if the holding function is obtained, extra work is required for attaching and detaching the holding member, so that the workability is reduced. Further, the function other than holding the insert material, that is, the handleability and the wettability are not improved at all.

[0013] Similarly, in the measures for fixing the insert material to the joint surface, the function other than holding the insert material is not improved at all. In addition, in the case of adhesion or adhesion, an adhesive or a pressure-sensitive adhesive is interposed between the joining surfaces, so that the joining quality may be deteriorated. In the case of spot joining, the welding is troublesome and causes a decrease in workability. In addition, in the case of magnetic bonding, it is not applicable when the reinforcing bar is a non-magnetic material.

As described above, it is impossible to solve all the problems such as handleability, holding, falling off, and wettability of the insert material by the use of the insert material by the conventional countermeasures. There is a risk of causing secondary adverse effects such as

An object of the present invention is to provide a method for diffusion bonding of a tube rod material which solves all the problems associated with the use of an insert material and which does not cause secondary harm such as poor bonding due to the presence of foreign matter. Is to do.

[0016]

According to the present invention, there is provided a diffusion bonding method for a pipe bar made of carbon steel, low alloy steel or stainless steel.
When butt-joining pipes or rods,
At least one of the opposing end faces of the joining base material
B: 10%, P: 10% or less, Fe: 50 by weight ratio
% Or less, Cr: 30% or less of B include one or more of the essential balance thickness of Ni and unavoidable impurities to form a plating film of 2~100μm
And butted the base material through this plating film
In the abutted part at 1200 ° C or higher
It is characterized by heating to a temperature below the point for 60 to 180 seconds .

[0017]

According to the diffusion bonding method of the present invention, since the insert material is provided integrally as a plating film on the bonding surface of the bonding base material, the step of inserting the insert material at the bonding site is unnecessary. Therefore, there is no danger of forgetting to insert or dropping out,
Reliable joining is performed, and joining workability is remarkably improved. In addition, there is no fear of a decrease in joining quality, which is a problem when an adhesive or a pressure-sensitive adhesive is used, and no trouble such as spot welding is required. Also, the present invention can be applied to a case where the joining base material is a non-magnetic material. In addition, since the plating film is wet between the bonding surface of the bonding base material and the bonding surface, a decrease in bonding performance due to poor wetting is prevented.

Hereinafter, the bonding base material and the plating film in the diffusion bonding method of the present invention and the bonding conditions will be described in detail.

The bonding matrix bonding base material, the shape to the bar and tubing rebar etc.
You. For the material, the carbon steel used in the reinforcing bar or the like, a low alloy steel and stainless steel.

Plating film The plating film gives the function of an insert material to the bonding surface of the bonding base material. In addition, it adheres closely to the joint surface and prevents poor wetting at the joint interface. The composition of the insert material that is commonly used is N
Although the i-Si-B system was found to be difficult to form as a plating film, the composition of the plating film in the present invention was a Ni-B (-P-α) system. α is Fe, C
r. The reasons for limiting the components are as follows.

B is an indispensable element for ensuring the wettability at the time of joining the plating film to the base material or the plating films.
If it is less than 1%, the wettability will be insufficient, and if it exceeds 10%, a long time will be required for diffusion, and the corrosion resistance of the joint will be reduced. Therefore, B is set to 1 to 10%.

P has the effect of lowering the melting point of the plating film. However, diffusion is slow and an embrittlement layer is easily formed. Therefore, P was added to 10% or less as necessary.

Fe has the effect of bringing the plating film closer to the base material composition. However, excessive addition not only impairs wettability at the time of joining, but also degrades corrosion resistance. Therefore, Fe was added at 50% or less as necessary.

Cr is effective in improving the corrosion resistance of the joint, but excessive addition of the Cr makes the joint brittle. Therefore, Cr is added at 30% or less as necessary.

The plating film may be formed on one of the bonding surfaces of the pair of bonding base materials to be bonded by diffusion, or may be formed on both of the bonding surfaces. When formed on one joint surface, FIG.
As shown in (A), the plating film 1 is interposed in each abutting portion by arranging the materials 2 with the plating film 1 facing in the same direction.

FIG. 1 shows a case in which both of the joining surfaces are formed.
(B) As shown in (C), the materials 2 with the plating film may be arranged in order, or the materials 2 with the plating film may be arranged while sandwiching the material 3 having no plating film. FIG.
(D) As shown in (E), a material 2 with a short plating film
Can be used as an intermediate joint. In either case, one or two plating films are interposed at the butted portions.

As a method of forming the plating film, electrolytic plating using a mixture of boric acid and boride (for example, trimethylamine borane) and, in some cases, phosphoric acid in an aqueous solution of nickel sulfate or nickel chloride as a plating solution is preferable. Also, electroless plating may be used.

The film thickness needs to be 2 μm or more in order to exhibit the function as an insert material. When the thickness is large, it takes a long time to form the film, which not only impairs the economical efficiency but also increases the diffusion time and the heating time.
Let m be the maximum. When plating films are stacked,
It is desirable that the total thickness be 100 μm or less.

Joining Conditions At the time of joining, as described above, a material with a plating film is disposed on at least one of the materials, and the materials are butted so that one or two plating films intervene at the butting portion. Next, as shown in FIG. 2, the materials are constrained by a jig 4 and the butted portion is heated by a high-frequency heating coil 5 or the like.

The heating temperature is 1200 ° C. or more and the joining base material
Below the melting point . The heating temperature was over 1200 ° C
Is to realize bonding in a short time. If a plating film having an extremely low melting point is used, bonding can be performed even at a temperature lower than 1200 ° C. However, it takes a long time to sufficiently diffuse B and the like in the plating film into the base material to obtain a sound bonded portion. Heating is not practical.

The heating time is at least 60 seconds in order to sufficiently diffuse B and the like in the plating film . However, more than necessary
The heating time is set to 180 seconds or less because the efficiency is reduced.
You.

It is preferable to press the butted portion during heating. If the applied pressure is less than 10 MPa, it takes a long time for diffusion, which impairs economic efficiency. On the other hand, if it exceeds 40 MPa, the deformation of the joint becomes excessive. Therefore, the pressing force is 10-40M
Pa is desirable. In some cases, there is no problem even if deformation occurs depending on the joining base material. In this case, a pressing force exceeding 40 MPa may be applied.

The bonding atmosphere is a non-oxidizing atmosphere. This is because in the case of an oxidizing atmosphere, poor wetting occurs due to oxidation of the bonding base material and the plating film, and a sound bonding portion cannot be obtained. As a method for obtaining a non-oxidizing atmosphere, for example, an inert gas, a nitrogen gas, or the like is released from the heating coil to the joint. In the tube material, an inert gas, nitrogen gas or the like is further supplied.

In applications where high cleanliness is required, such as for semiconductor manufacturing equipment, clean pipes used for piping are:
The outer surface only needs to be a non-oxidizing atmosphere, but the inner surface needs to have its dew point further reduced to -70 ° C. If the dew point of the atmosphere on the inner surface side exceeds -70 ° C., an oxide scale is formed on the inner surface of the joint, and the corrosion resistance deteriorates. It should be noted that the dew point of the atmosphere on the outer surface side may be controlled to −70 ° C. or less. However, since the corrosion resistance required for the outer surface of the tube is usually low, the dew point control to that point is not required.

The necessary atmosphere on the outer surface side can be obtained, for example, by supplying Ar gas having a purity of 99.99% or more at a flow rate of 2 liter / min or more. The atmosphere required on the inner surface side is, for example, an Ar gas having a purity of 99.999% or more in a pipe.
The gas can be obtained by flowing gas at a flow rate of 2 liters / min or more for at least 3 minutes before joining during joining using a clean pipe, or by degassing the inside of the pipe to a high vacuum.

[0036]

Next, examples of the present invention and comparative examples will be described.

Example 1 (Example of joining strips ) Nominal diameter D specified in JIS G3112 SD345
51 Both ends of deformed reinforcing bar (length 300mm)
It was finished to a maximum of 50 μm, and electroplated on both end surfaces. Both ends of the rebar having a length of 10 mm were finished to a surface roughness Rmax of 50 μm, and both ends were subjected to electrolytic plating to form an intermediate joint.

In electrolytic plating, NiSO ₄ + NiCl ₂ +
Energization is performed in H ₃ BO ₄ + (CH ₃ ) ₃ NBH ₃ or a solution to which phosphoric acid or chromic acid is added, and plating of various compositions and thicknesses is performed by changing the solution composition, current, and energization time. A film was formed.

A plating film was formed on both end faces.
The rebars of the books were butted and constrained by a jig, and the butted portions were subjected to high-frequency induction heating while applying pressure (FIG. 1).
(B)). A reinforcing bar having a plated film on both end surfaces and a reinforcing bar having no plated film on both end surfaces were butted and similarly joined (FIG. 1 (C)). Simultaneous joining was carried out by sandwiching a 10 mm long reinforcing bar (intermediate joint) having plated films formed on both end surfaces between two reinforcing bars having plated films formed on both end surfaces (FIG. 1 (D)). Between two rebars that do not have a plating film on both end surfaces, a length of 10 mm with a plating film formed on both end surfaces
(See Fig. 1)
(E)).

In each joining, a nitrogen gas was blown at a flow rate of 100 liter / min to the butted portion through a heating coil.

For comparison, two rebars having no plating film were joined using a foil-like insert material. The composition of the insert material is Ni-7% Cr-3% Fe-4.5%
Si-3.2% B and thickness were 25 μm.

After joining 100 joints under each condition, the joints after joining were subjected to a tensile test and a bending test in the same shape, and the pass rate in each test was determined. In the tensile test,
In the bending test, those in which the joints were broken or in which the joints were cracked were rejected. Table 1 shows the joining conditions and the acceptance ratio.

[0043]

[Table 1]

Nos. 1 to 11 are examples of the present invention using a plating film as an insert material. Both the tensile test and the bending test showed a pass rate of 100%. When a plating film is formed on the end face of the reinforcing bar to be joined (Nos. 1 to 9), use of the insert material is not forgotten and the insert material does not fall off. When the intermediate joint is used (Nos. 10 and 11), if the intermediate joint is forgotten to be inserted or falls off, a large difference occurs in the appearance, so that the presence or absence of the intermediate joint can be accurately determined after joining.

No. 12 is a conventional example using a foil insert material. Due to the bonding in the laboratory, no deterioration in bonding properties due to poor wetting has occurred. However, in-situ bonding may cause poor bonding due to insufficient wetting.

No. 13 is an example of joining when there is no insert material. The pass rate is very low. However, there are cases where a small number is passed. The appearance of the joint is
This is the same as that using the insert material. Therefore, No.
When a foil-shaped insert material is used as shown in 12, it is impossible to accurately determine the presence or absence of the insert material after joining even if a test is performed.

Nos. 14 to 18 are examples in which a plated film is used as the insert material, but the pass rate is low except for No. 17 because the composition of the plated film or other bonding conditions are inappropriate.

No. 17 shows a high pass rate, because the heating is performed for 30 minutes in consideration of the thickness of the plating film, and the efficiency is very low due to long-time heating. Incidentally, the pass rate is low as in No. 16 when the heating time is about 3 minutes.

Example 2 (Example of joining pipe materials) Electrolytic plating was applied to both end faces of a stainless steel pipe shown in Table 2 and a carbon steel pipe shown in Table 3, and the steel pipes were joined in the form shown in FIG. 1 (B). SGP is a carbon steel pipe for piping specified in JIS G3452 and has an outer diameter of 34 mm x a wall thickness of 3.2 mm.
STS38 is a carbon steel pipe for high-pressure piping specified in JIS G3455 and has an outer diameter of 28 mm x wall thickness of 4.0 mm. STKS is a carbon steel pipe made of structural alloy steel specified in JIS G3441 and has an outer diameter of 50.8 mm x wall thickness of 2. 0.3 mm. In addition, all stainless steel tubes have an outer diameter of 34 mm and a wall thickness of 1.2.
mm. Table 4 shows the results of evaluating the joint after joining in the same manner as in Example 1. If the conditions are appropriate, the plating film is also effective for joining the tube material.

[0050]

[Table 2]

[0051]

[Table 3]

[0052]

[Table 4]

Example 3 (Example of joining a clean pipe) SUS316L, high alloy N10276 and S3125
4 (Table 5), the inner diameter of which is 6 mm or less, especially the maximum roughness of the inner surface is made 0.6 μm or less by electrolytic polishing of the inner and outer surfaces.
m, the end face of a clean pipe with a length of 300 mm is surface roughness Rm
It was processed to ax × 10 μm or less, and electroplating was performed on both end surfaces thereof.

In the electrolytic plating, NiSO ₄ + NiCl ₂ +
Energization is performed in H ₃ BO ₄ + (CH ₃ ) ₃ NBH ₃ or a solution to which phosphoric acid or chromic acid is added, and plating of various compositions and thicknesses is performed by changing the solution composition, current, and energization time. A film was formed.

[0055]

Next, a plating film 2 was formed on both end surfaces.
Butt the clean pipes and restrain them with a jig,
The butted portion was subjected to high-frequency induction heating. At this time, the outer surface of the butted portion has a purity of 9 supplied through the heating coil.
Shielded with 9.99% Ar gas (5 L / min). In addition, Ar having a purity of 99.999% is contained in the pipe.
By flowing a gas at 5 liter / min, an atmosphere having a dew point of -70 ° C or less was formed. The heating temperature was monitored by a non-contact type thermometer and used for temperature control.

A bending test with a bending radius of 24 mm was performed on the joined portion of the clean pipe after joining to evaluate the strength of the joined portion. The inner flatness and corrosion resistance of the joint were investigated using test pieces taken from the joint and its vicinity. In the investigation of corrosion resistance, 2% or 30% concentration of FeCl _3.
A 3 × 20 mm filter paper immersed in a 6H ₂ O aqueous solution was brought into close contact with the inner surface of the joint, and kept in an atmosphere at 25 ° C. for 6 hours to check for occurrence of pitting corrosion. Table 2 shows the results. Corrosion resistance A shows no pitting at 2% FeCl ₃ , and B shows pitting at 2% FeCl ₃ .

For comparison, T for clean pipe was used.
The same evaluation was performed on the joints welded by the IG welding machine.

B1 is joining by TIG welding. Although there is no problem with the bonding property, the flatness of the inner surface of the bonding portion is low due to the backside bead, and there is a problem with the cleanliness. B2 is diffusion bonding, but the bonding is incomplete because there is no plating film on the pipe end surface. B3 to B5 are cases where a plating film is formed on the end face of the pipe and melt diffusion bonding is performed. However, in B3 and B4, there was a problem in the composition of the plating film, so that the bonding was incomplete, and in B6, the corrosion resistance of the bonded portion was lowered because the dew point of the atmosphere on the inner surface side of the pipe was high.

[0060] For these, an example of the present invention A1 to 7
Has no problem in bonding, and has good flatness and corrosion resistance on the inner surface of the bonded portion.

[0061]

[Table 6]

[0062]

As described above, according to the method of the present invention for diffusion bonding of a tube rod , the insert material is formed integrally with the base material bonding surface as a plating film. This eliminates the need for handling of insert materials and is excellent in joining workability. In addition, there is no fear of forgetting to insert the insert material or falling off. Therefore, reliable joining can be efficiently performed even in-situ joining such as joining of reinforcing bars. Also, set appropriate joining conditions
On selected, the wettability of the base material bonding surface and the insert member <br/> superior further adhesive or an adhesive, spot welding, because there all be secondary negative effect such as in the case of using magnetically attached From this aspect
An improvement in the bondability can be expected .

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of material arrangement when joining the material of the present invention.

FIG. 2 is a schematic view showing an example of a method for joining the materials of the present invention.

[Description of Signs] 1 Plating film 2 Material with plating film 3 Material without plating film

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Fumio Kashimoto 4-5-33 Kitahama, Chuo-ku, Osaka City, Osaka Prefecture Inside Sumitomo Metal Industries, Ltd. (72) Inventor Kazuhiro Ogawa 4-5-Kitahama, Chuo-ku, Osaka City, Osaka Prefecture No. 33 Sumitomo Metal Industries, Ltd. (56) References JP-A-52-77854 (JP, A) JP-A-57-142782 (JP, A) JP-A-58-132380 (JP, A) 2-121782 (JP, A) JP-A-6-142948 (JP, A) JP-A-61-216877 (JP, A)

Claims (1)

(57) [Claims] 1. From carbon steel, low alloy steel or stainless steel
When butt-joining pipes or rods
At least one of the opposing end faces of the joining base material to be joined and joined
In addition , B: 10% by weight, P: 10% or less, Fe:
Forming a plating film containing 50% or less, Cr: 30% or less, one or more of which B is indispensable, the balance being Ni and unavoidable impurities and having a thickness of 2 to 100 μm.
Then, the joining base material is butted through this plating film.
With the butted part in the contacted state, 1200 ° C or more
A method for diffusion bonding of a tube bar, comprising heating the tube to a temperature lower than the melting point for 60 to 180 seconds .