JPH04354842A - Electrode material for resistance welding - Google Patents

Abstract

PURPOSE:To offer an electrode material having a long service life, good in strength and high in productivity. CONSTITUTION:This is an electrode material for resistance welding having a compsn. contg., by weight, 0.2 to 1.2% Cr, 0.05 to 0.6% Zr as well as total 0.4 to 1.4% Cr and Zr, 0.005 to 0.05% Si, 0.001 to 0.1% B and the balance Cu with inevitable trace elements.

Description

[Detailed description of the invention]

[Purpose of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode material used in resistance welding, and more particularly to an electrode material for resistance welding with improved life and strength.

0002

[Prior Art] Resistance welding is a method in which materials to be welded are piled up, the joint is pressurized with an electrode, a welding current is passed through this, and the resistance heat generated at the joint is used to locally weld the materials.
It is widely used in fields such as electronic equipment, aircraft, automobiles, architecture, and vehicle industry.

[0003] When resistance welding is performed, the temperature of the electrode increases due to the heat generated, and large pressure is applied to the tip of the electrode due to pressurization. If this kind of situation is repeated,
The tip of the electrode may become sagging, the electrode material may become alloyed at the contact interface with the material to be welded, and furthermore, it may cause sticking, or welding with the material to be welded, making it unusable as an electrode. Therefore, electrode materials are required to have high strength (hardness) and long life at high temperatures, and Patent No. 931368
Chromium-copper alloys have been used as shown in No.
It cannot be said that the lifespan is necessarily sufficient, and it has been desired to further improve the characteristics.

[0004] In addition, such electrode materials are generally subjected to cold working after solution treatment, but the cold working rate is 40 to 40%.
Good characteristics could not be obtained unless the ratio was as high as 80%. This leads to an increase in manufacturing man-hours, so
There was a need for something that could provide good strength even at low cold working rates.

[0005]

[Problems to be Solved by the Invention] As described above, the characteristics of conventional electrode materials for resistance welding are not sufficient, and good characteristics cannot be obtained unless the cold working rate is increased during manufacturing. There was a problem. An object of the present invention is to provide an electrode material for resistance welding that has a long life, high strength, and has good characteristics even at a low cold working rate. [Structure of the invention]

[0006]

[Means for Solving the Problems and Effects] In order to achieve the above object, the present invention contains Cr in a proportion of 0.2 to 1.0% by weight.
2%, Zr 0.05 to 0.6%, and Cr and Z
The sum of r is 0.4~1.4%, and the Si is 0.005~
Contains 0.05%, B 0.001 to 0.1%,
The present invention provides an electrode material for resistance welding, characterized in that the remainder consists of Cu and unavoidable trace elements.

[0007] Cr and Zr constituting the electrode material for resistance welding in the present invention have the effect of improving strength and reducing fatigue of the electrode tip, and Cr is 0.2 to 1.2 wt%,
Zr is 0.05 to 0.6 wt%, and Cr and Zr
The sum of these is contained in the range of 0.4 to 1.4 wt%. If it is less than these conditions, the strength will be insufficient, and if these conditions are exceeded, segregation will likely occur during ingot production. Practically, 0.3 to 0.8 wt% of Cr, Z
It is preferable to contain 0.1 to 0.4 wt% of r.

[0008] Furthermore, Si has the effect of improving strength and electrical conductivity, and is contained in an amount of 0.005 to 0.05 wt%. If it is less than 0.005 wt%, the effect will be small, and if it exceeds 0.05 wt%, the conductivity will decrease. Practically 0.01 to 0.04 wt%
It is preferable to contain.

Furthermore, B has the effect of improving the strength without lowering the electrical conductivity, especially in the region where the cold working rate is low (1
0 to 60%).
001 to 0.1 wt%. If it is less than 0.001, the effect will be small, and if it exceeds 0.1 wt%, it will collect at grain boundaries, etc., and hot workability will deteriorate. Practically speaking, it is preferably contained in an amount of 0.01 to 0.07 wt%. Cu, which constitutes the remainder, has high electrical and thermal conductivity and is suitable for use as a base material for electrode materials. Note that this alloy is allowed to contain impurities that are unavoidable during manufacturing.

[0010] The electrode material for resistance welding of the present invention can be obtained by, for example, casting a material having the above-mentioned composition by a melting method or the like to form an ingot, hot working it, and heating it at 850 to 1000°C.
After solution treatment for 0.5-3 hours, the cold working rate is 10-
60%, preferably 10 to 40% due to the manufacturing process, to form it into a predetermined shape, and further 450 to 600
Aging treatment is performed at ℃ for 1 to 5 hours, and finally it is manufactured by machining to a predetermined size.

The resistance welding electrode material manufactured in this manner has an electrical conductivity of 65 to 85 IACS%, which is an appropriate value for an electrode, and under the usage conditions: 400 to 600 IACS%.
Good strength can be obtained even at ℃. Furthermore, the welding resistance is also good.

0012

EXAMPLES The present invention will be illustrated by the following examples. Example 1

[0013] Sample No. in Table 1. Metal materials having the compositions shown in 1 to 5 (end A) were prepared respectively, and an ingot of 180φ x 7501 mm was formed by high frequency melting method.
After heating at 0° C. for 1 hour, a round bar of 25φ was formed by hot working. This was solution-treated at 960°C and then cold-worked into a 16φ round bar. Furthermore, this round bar 4
After aging at 80°C for 2 hours, it was air cooled and cut to create a resistance welding electrode with an outer diameter of 16φ and a tip of 6φ in the shape shown in Figure 1 with a cold working rate of 59%. did. Similarly, as a comparative example, No. A sample having the composition shown in 6A was prepared in the same manner. Example 2

[0014] An ingot having the same composition as in Example 1 (sample number suffix B) was heated at 800°C for 1 hour and then hot worked to form a round bar of 20φ. This was processed in the same manner as in Example 1 to create a resistance welding electrode having the same shape as in Example 1 with a cold working rate of 36%. Similarly, as a comparative example, No. A sample having the composition shown in 6B was prepared in the same manner.

The electrical conductivity and hardness of the resistance welding electrodes prepared in Examples 1 and 2 and Comparative Example were measured. The results are shown in Table 1. In addition, welding characteristics were evaluated by the following method.

That is, a 1 mm thick zinc steel plate on which a zinc layer was formed with a thickness of 2 to 5 μm was attached to a welding machine as a welding material, welding current: 14000 A, electrode pressure: 400
Resistance welding (spot welding) was performed under the conditions of Kgf and energization cycle: ON for 2 seconds and OFF for 2 seconds. Here, the diameter of each electrode tip increased from the original 6 mmφ to 9 mmφ due to thermal deformation, and the welding resistance of each electrode was evaluated based on the presence or absence of welding at the time when re-polishing became necessary. As a result N
o. No welding occurred in samples Nos. 1 to 6, and no decrease in welding resistance due to the addition of B was observed.

[0017] Also, No. Regarding No. 2 and No. 6, Table 2 shows the results of evaluating the lifespan by the number of dots until repolishing was required under the above-mentioned conditions. From this result, No. The second sample is No. It can be seen that a longer life than 6 was obtained. Furthermore, the results of measuring the temperature characteristics of hardness are shown in FIG. This result shows that good strength is obtained even at the working temperature (400 to 600°C).

These evaluation results show that the resistance welding electrode material of Example 1 exhibits long life, high strength, and good characteristics. Further, it can be seen from Example 2 that even at a low cold working rate, properties equivalent to or better than those of the conventional method were obtained.

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

As described in detail above, the present invention provides a resistance welding electrode material that has a long life, excellent high-temperature strength, and high productivity.

[Brief explanation of drawings]

FIG. 1: Resistance welding electrode according to an example.

FIG. 2 is a diagram showing the temperature characteristics of hardness in the resistance welding electrode according to the example.

[Explanation of symbols]

1... Electrode tip

Claims (1)

[Claims] Claim 1: 0.2 to 1.2% Cr by weight, Z
r is 0.05 to 0.6%, the sum of Cr and Zr is 0.4 to 1.4%, and Si is 0.005 to 0.05.
%, contains 0.001 to 0.1% of B, and the balance is Cu
and an unavoidable trace element.