JPH03106582A - Welding method - Google Patents

Abstract

PURPOSE:To obtain mechanical strength to the same extent as that of base metals by subjecting Cu or Cu alloy members which are plated with Ni to heat treatment in advance, diffusion Ni in Cu or a Cu alloy and joining and welding the members formed with an alloy layer of Ni and Cu. CONSTITUTION:The surfaces of the oxygen free Cu members 2 are electroless- plated with Ni and these are heat-treated in a vacuum and a cupronickel layer 1 is formed on the surfaces thereof. These Cu members are joined and held in a quartz vessel and while supplying shielding gas, these members are irradiat ed with a laser beam 4 and welded. By this method, welding excellent in joining strength can be performed.

Description

[Detailed Description of the Invention] (Summary) From copper or copper alloy. Regarding the welding method for parts, the aim is to make the welded part maintain the same mechanical strength as the base metal, by joining parts made of nickel-plated copper or copper alloy, and applying a laser beam to the joined part. In the irradiation and melting welding method, a member made of nickel-plated copper or copper alloy is heat-treated in advance to diffuse nickel into the copper or copper alloy, and the surface of the member is coated with nickel and copper. The welding method is characterized by joining and welding the alloy layers formed thereon.

[Industrial application field]

The present invention relates to a method for welding members made of copper or copper alloys.

Copper (Cu) has a thermal conductivity of 3.85 J/cm-s-k
(However, the temperature is 0°C), so it is used as a metal material to construct equipment that requires water cooling.

In addition, copper alloys have excellent spring elasticity like beryllium copper and phosphor bronze, and materials with excellent corrosion resistance can be made.
Mechanical parts and component parts are made by joining U members and Cu members, Cu members and Cu alloy members, etc.

Soldering or brazing is often used to weld metal parts, but in this case it is necessary to heat the metal parts sufficiently.

However, for materials made of beryllium copper or phosphor bronze that have already been heat treated under optimal conditions, heating deteriorates the spring elasticity.

Therefore, laser welding or electron beam welding is used when there are members that cannot be heated.

[Conventional technology]

When performing laser welding or electron beam welding, welding is difficult because the beam irradiation time is short and copper has high thermal conductivity, so human heat during welding escapes into the base metal.

Hereinafter, a conventional technique regarding laser welding performed in 1a will be explained.

In order to solve this problem, the inventors have proposed applying nickel (N1) plating to Cu and Cu alloys, which are the parts to be welded, and then welding them. 〈Unexamined Japanese Patent Publication 1986
-575699. Published on March 22, 1986> In other words, since Ni has a low thermal conductivity of 0.9 lJ/cIl-sk (at 0°C), the heat of the weld can be reduced by interposing Ni in the weld. Conductivity decreases and laser welding becomes possible.

By using this method, welding becomes possible because the penetration depth of the weld increases, but because the laser irradiation time is short, Ni does not diffuse uniformly, and areas with high and low Ni concentrations are separated. As a result, the strength of the welded portion becomes lower than that of the base metal.

Therefore, there was a problem in that it could not be used in applications where the welded part needed to have the same mechanical strength as the base metal. [Problem to be solved by the invention] As described above, when laser welding a member made of Cu or a Cu alloy, it is possible to lower the thermal conductivity of the irradiated part by applying Ni plating to the member and performing the welding afterwards. Therefore, laser welding is possible, but the problem is that the mechanical strength of the welded part decreases, making it impossible to apply it to applications where the welded part needs to have the same mechanical strength as the base metal. [Means for solving the problem] The above problem is solved by a method of joining members made of Ni-plated Cu or Cu alloy, and irradiating the joint with a laser beam to melt and weld the Ni-plated part. Heat-treating the applied Cu or Cu alloy member in advance to diffuse Ni into the Cu or Cu alloy,
This problem can be solved by using a welding method characterized by joining and welding an alloy layer of Ni and Cu formed on the surface of the member.

[Effect]

When members made of Ni-plated Cu or Cu alloy are joined and the joining position is irradiated with a laser or electron beam, the Ni plating layer (melting point 1452°C), which has low thermal conductivity, melts due to the irradiation, and this Cu (melting point 1
084°C) or welding is performed by melting the Cu alloy.

However, the mechanical strength is inferior to that of the base metal, so when a mechanical strength test is performed, a rupture occurs at this weld location. The inventors investigated the cause of this and found that because the time from the start of melting due to laser irradiation to the end of solidification is extremely short, less than 50 ms, Ni cannot be uniformly diffused, resulting in a non-uniform weld. It turned out that it was because of the fact that

Therefore, in the present invention, prior to welding, a member made of Ni-plated Cu or a Cu alloy is heat-treated just below its melting point to coat the surface with Cupronickel IJ, which is an alloy of Ni and Cu.
It forms the

Because of this, cupronickel is also called white-shouldered, and as the Ni content increases, it loses its reddish tinge, and when the Ni content reaches 20%, it becomes completely silvery-white, and its strength and corrosion resistance increase. There is.

Figure 1 shows a specimen made of Cu plated with Ni and having a thickness of 10 μm, which was heat treated in vacuum at different temperatures and treatment times of 800°C, 900°C and 1000°C, and the specimens were bonded together. The figure shows the joint strength when laser welding is performed. As shown in FIG. 2, the sample was a Cu member 2 which was provided with a Ni plating layer and then heat-treated to form a cupronickel layer 1.
After these are joined together, a laser beam 4 emitted from a laser light source 3 is focused on the joint by a condenser lens 5 and welded. From the results shown in Figure 1, it is clear that in order to maintain excellent bonding strength, it is best to form a cupronickel layer by annealing just below the melting point, and it is necessary to extend the heat treatment time as the annealing temperature decreases. The present invention performs welding with excellent joint strength by forming a Kipronickel layer with excellent mechanical strength and low thermal conductivity on the surface of a Cu member. [Example] Electroless Ni plating with a film thickness of 10 μm was applied to the surface of a member made of oxygen-free Cu, and this was heat-treated at 1000° C. for 1 hour in a vacuum of 1 xio-' Torr to coat cupronickel on the surface. A layer was formed. This Cu member was bonded and held in a quartz container, and argon (Ar) was used as the shield gas, and the shield gas pressure was 1
．． Welding was performed by laser irradiation using a neodymium (Nd)-YAG laser light source under the conditions of an average output of 120 W, a pulsed laser of 30 pps, a pulse width of 2 IIIs, and a lens focal length of 100 mL, while supplying a shielding gas flow of 5 kg/m" and a shielding gas flow of 5130 N/min. went.

As a result, the bonding strength was 20 kg/ma+” and Cu
The fracture occurred in the heat-affected zone surrounding the weld, not at the weld location.

〔Effect of the invention〕

By implementing the present invention, it is possible to have a joint strength comparable to that of the base metal, and since the welded part and the surface of the base metal have the same bonding strength as cupronickel, corrosion resistance can also be improved. Note that although the case of laser welding has been described, the results are similar in the case of electron beam welding.

[Brief explanation of drawings]

Figure 1 is a diagram showing the bonding strength of Ni-plated Cu members, Figure 2
The figure is a cross-sectional view explaining laser welding. In the figure, 1 is a cupronickel layer, 2 is a Cu member, and 4 is a laser beam. N1〆-/Formula Cu enclosure material swell 8r strength Σ does not show peeling 1 Fig. 2.
Figure-467-

Claims (1)

[Claims] A method of joining members made of nickel-plated copper or copper alloy, and irradiating the joined part with a laser beam to melt and weld, A welding method characterized by heat-treating a member in advance to diffuse nickel into the copper or copper alloy, forming an alloy layer of nickel and copper on the surface of the member, and then joining and welding.