JPH0832935B2 - High strength and high toughness Cu alloy with little characteristic anisotropy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention has high strength and high toughness, has excellent solder adhesion, and has little difference between the properties in the processing direction and the direction perpendicular to the processing. The present invention relates to a Cu alloy having little characteristic anisotropy.

[Prior Art] Generally, in% by weight (hereinafter,% indicates weight%), Ti: 2 to
The Cu-Ti alloy containing 5% has an excellent precipitation hardening ability and, therefore, a strength comparable to that of beryllium copper can be obtained. Therefore, high strength and high toughness are required for electrical connections such as connectors and switches. It is used as a spring material for contacts.

[Problems to be solved by the invention]

On the other hand, in recent years, demands for smaller and lighter parts are strict, and along with this, it is inevitable to reduce the wall thickness and increase the strength, so that the workability tends to increase. In such cases, the properties in the machining direction and the direction perpendicular to the machining show a marked difference, and such characteristic anisotropy is fatal for the spring material, especially the spring limit value and the repeated bending property. It strongly appears in.

In particular, this characteristic anisotropy is prominently exhibited in the above-mentioned conventional Cu-Ti alloys, and therefore, during processing, a large degree of processing cannot be obtained, and further, the characteristic anisotropy is increased during the processing step. Requires special high temperature heat treatment to erase,
As a result, not only becomes a complicated processing step, but also causes a cost increase, and causes difficult problems such as the occurrence of problems such as crystal coarsening and brittleness due to high temperature heat treatment, and the occurrence of adverse effects such as oxidation. This is the current situation.

[Means for solving problems]

Therefore, the present inventors, from the above viewpoints, pay attention to the above-mentioned conventional Cu-Ti alloy having high strength and high toughness, and conduct research to improve it and reduce the characteristic anisotropy. As a result, when the conventional Cu-Ti alloy contains Cr and an iron group metal together as alloy components, the property anisotropy of the processed material, particularly the processed material with a high degree of processing, is significantly suppressed. In addition, primary crystal particles of Ti-iron group metal intermetallic compound
As a result of being effectively miniaturized by the action of the Cr component, bending workability and plating property are remarkably improved, and when Ca, Mg, Zn, and Cd are additionally contained, solder adhesion is improved. We have found that it will be improved further.

The present invention has been made based on the above findings, in which Ti: 2.1 to 5%, Cr: 0.02 to 0.5%, one or more iron group metals: 0.15 to 0.95%, Ca, One or more of Mg, Zn, and Cd: 0.0
It is characterized by a high-strength and high-toughness Cu alloy having a composition of 1 to 0.5% and the balance of Cu and unavoidable impurities with little characteristic anisotropy and excellent solder adhesion.

Next, the reason why the composition of the Cu alloy of the present invention is limited as described above will be explained.

(A) Ti The Ti component has the effect of improving the strength and toughness of the alloy, but if its content is less than 2.1%, the desired effect cannot be obtained on the other hand, while its content is 5%. If the content exceeds this range, the heat-related workability will deteriorate, so the content was set to 2.1-5%.

(B) Cr and iron group metal Both of these components suppress the occurrence of characteristic anisotropy in the processed material in the coexisting state as described above, and the Cr component is an intermetallic compound dispersed in the matrix. There is an effect of refining the primary crystal particles to improve bending workability and plating property, but the content thereof is Cr: less than 0.02% and iron group metal: less than 0.15%, the desired effect cannot be obtained in the above operation, On the other hand, if the content of Cr exceeds 0.5% and the iron group metal exceeds 0.95%, the crystallized particles in the base material become coarse, and the bending workability and the matting property are deteriorated. Therefore, the contents were determined to be Cr: 0.02 to 0.5% and iron group metal: 0.15 to 0.95%, respectively.

(C) Ca, Mg, Zn, and Cd These components have the effect of improving the solder adhesion as described above, but if the content is less than 0.01%, the desired good solder adhesion is secured. However, if the content exceeds 0.5%, a remarkable deterioration phenomenon in solder adhesion will appear, so the content is set to 0.
It was set at 01-0.5%.

〔Example〕

Next, the Cu alloy of the present invention will be specifically described by way of Examples.

Using a normal high-frequency vacuum melting furnace, prepare a molten metal with the composition shown in Table 1 in a graphite crucible and cast it into a metal ingot with a diameter of 60 mmφ and a weight of 5 kg. Width: 100 mm × height: 6 mm by forging and hot rolling
After holding it at a temperature of 920 ° C for 1 hour, subject it to solution heat treatment under the conditions of rapid cooling in water, and then cold rolling and 360 ~ 5
Repeated intermediate annealing at a temperature in the range of 00 ℃,
Rolling rate: 50% final cold rolling, finally temperature: 36
By subjecting to strain relief annealing held at 0 ° C. for 20 minutes, thin sheet materials of Cu alloys 1 to 21 of the present invention and comparative Cu alloys 1 to 7 each having a plate thickness of 0.25 mm were manufactured.

Then, the tensile strength was measured in the rolling direction and the direction perpendicular to the rolling in these thin plate materials, and the spring limit value was measured using a burr / spring limit tester on one side. Use a jig to hold the test piece in an upright position, and alternately bend the test piece 180 ° alternately left and right centering on the sandwiched root part, and repeat the number of times until cracks occur in the bent part (90 ° = 1 Times and calculation),
In addition, the test piece was
It has a composition of Sn-37% Pb and is immersed in molten solder at a temperature of 230 ° C. to deposit a solder having a thickness of about 10 μm on the surface thereof. To ℃
Heat treatment was performed under the condition of holding for 500 hours, and the presence or absence of peeling of the solder after heating was observed. The results are shown in Table 1.

〔The invention's effect〕

From the results shown in Table 1, the Cu alloys 1 to 21 of the present invention,
Both have high strength and high toughness, and the anisotropy in these characteristics is extremely small, and further, the solder adhesion is excellent, while as seen in the comparative Cu alloys 1 to 7, When the content of at least one of the constituents (marked with * in Table 1) is out of the range of the present invention, it is clear that at least one of the above-mentioned characteristics is inferior. .

As described above, the Cu alloy of the present invention has high strength and high toughness and has very little anisotropy of these properties, and this property anisotropy can be increased by increasing the workability. Since it is not necessary, it can be made even thinner and has excellent solder adhesion. Therefore, when it is used as a spring material for electrical contacts such as connectors and switches, it is possible to reduce its weight and size. In addition to making it possible, it has excellent performance over a long period of time.

Claims (1)

[Claims] 1. Ti: 2.1 to 5%, Cr: 0.02 to 0.5%, one or more of iron group metals: 0.15 to 0.95%, one of Ca, Mg, Zn, and Cd. Or two or more: 0.0
High strength and high toughness Cu with little characteristic anisotropy, characterized by containing 1 to 0.5%, and the balance being Cu and inevitable impurities.
alloy.