JPS6154100B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a Cu-Ni-Sn alloy, and more specifically, a Cu-Ni-Sn alloy in which coarsening of crystal grains is suppressed by the addition of B. This invention relates to spring copper alloys for equipment.

Cu-Ni-Sn copper alloys are used as spring materials for electrical equipment in connectors, relays, etc., similar to Cu-Be alloys (beryllium bronze) and phosphor bronze, which is a Cu-Sn alloy with P added. . Especially, 8.5~
Copper alloy containing 10.5% Ni and 1.8-2.8% Sn is
It is well known as CDA-725 alloy. Various improvements have been made to Cu-Ni-Sn based copper alloys (for example, JP-A-52-136828;
JP-A-52-136829, JP-A-53-26223, and JP-A-54-57422).

Cu-Ni-Sn based copper alloys have various excellent properties (corrosion resistance, electrical conductivity, solderability, creep resistance, high strength), but on the other hand, they have the disadvantage of causing surface roughness. That is, when manufacturing connectors and the like, bending is unavoidable, and roughness such as orange peel or wrinkles occurs on the surface of the Cu-Ni-Sn alloy at the bent portion. Such surface roughness reduces the adhesion of the plating layer during plating after bending, and if plating is applied before bending, the plating layer is likely to peel off.

An object of the present invention is to provide a Cu--Ni--Sn spring copper alloy for electrical equipment in which the surface roughening phenomenon does not occur during bending or is very small as described above.

According to the invention, this purpose is achieved by using 5 to 20% by weight of
This is achieved by a spring copper alloy for electrical equipment containing Ni, 1 to 8% by weight of Sn, and 0.02 to 1.0% by weight of B, with the remainder consisting of Cu and impurities.

In Cu-Ni-Sn copper alloys, if Ni is less than 5% by weight and Sn is less than 1% by weight, sufficient strength cannot be obtained due to precipitation hardening, and if Ni is 20% by weight or Sn8
If it exceeds % by weight, work hardening becomes extremely large and workability deteriorates.

The effects of appendix B according to the present invention are considered to be as follows.

The coarser the crystal grains, the more pronounced the roughening phenomenon in the bent portion becomes. In other words, plastic deformation of a material caused by bending generally involves the deformation of individual crystal grains that aggregate as a unit to form the overall deformation, but the crystal grains on the surface of the material may bulge out during deformation. The larger the crystal grains, the rougher the surface becomes. Therefore, the rough skin phenomenon can be solved by making the crystal grains finer. On the other hand, the grain size of expanded copper materials is generally
It depends on the final solution temperature or final sintering temperature. In the case of Cu-Ni-Sn copper alloy,
In particular, the higher the amount of Sn, the more precipitation-hardened it is.
Solution heat treatment is performed at a temperature of 800°C, and crystal grains easily become coarse at such high temperatures. Therefore, by adding B to the Cu-Ni-Sn copper alloy, we can create a B compound (Ni-B intermetallic compound) that is stable even at the temperature where the crystals become coarse as described above.
can be uniformly and finely dispersed to prevent grain boundary movement (coarsening). In addition, the crystal grains can be made finer than in the case where B is not added. If the amount of B added is 0.02% by weight or less, the amount of B compound precipitated is extremely small and there is no effect of preventing crystal grain coarsening. Furthermore, if the amount of B added is 1.0% by weight or more, the precipitates become coarse and the cold workability and mechanical properties deteriorate, making the steel unsuitable for practical use.

Furthermore, the added B acts as a deoxidizing agent during melting and casting, and has the effect of producing a sound ingot.

Example B addition amount is 0, 0.02, 0.05, 0.2, 0.5 and 1.0
Instead of weight%, Cu-9wt%Ni-6wt%Sn
The alloy was melted to make ingots. Furthermore, B is
It is a Cu-B master alloy and was added after the other components were melted. The manufactured ingot was subjected to solution treatment at 825° C. for 10 hours (ie, heated for 10 hours and then quenched in water). Thereafter, the ingot surface was externally milled, and cold annealing at 825°C for 1 hour and annealing at 825°C for 1 hour were repeated to give a final plate thickness of 0.6 mm. The plate material thus obtained was subjected to final annealing at 825° C. for 1 hour, then water quenched, and the size of crystal grains was measured. The results are shown in FIG. It can be seen that the addition of B made the crystals finer. Furthermore, an optical microscopic photograph (320
2 times) were photographed for the case without B addition and for the case with 0.05% by weight B addition. Figure 2 shows no B addition (Cu
-9%Ni-6%Sn), Figure 3 is a micrograph of
Addition of 0.05% by weight (Cu-9%Ni-6%Sn-0.5B)
This is a microscopic photograph. These photographs also show that the addition of B does not cause the crystal grains of the Cn-Ni-Sn based copper alloy to become coarse.

The size of the crystal grains of the plate material immediately after final annealing (before rolling) hardly changes even if a processing rate of about 50% is applied by subsequent rolling. In other words, the crystal grain size at the time of final annealing remains almost the same as the crystal grain size of the rolled material. Therefore, when comparing the surfaces of the bent parts when the processed products in these cases (no additives and 0.05 wt. However, with the 0.05 wt% B additive material, wrinkles and rough skin phenomena such as orange peel are not observed. In addition, the bending process is performed with a plate thickness of 0.6 mm and a bending diameter of 0.6 mm.
The bent surface was observed using a Roubaix.

[Brief explanation of the drawing]

Figure 1 is a chart showing the relationship between the amount of B added and the grain size in a Cu-Ni-Sn based copper alloy, and Figure 2 is a graph showing the relationship between the amount of B added and the size of crystal grains in a Cu-Ni-Sn based copper alloy.
Figure 3 is a micrograph of a wt% Sn alloy;
It is a micrograph of a weight% Sn alloy.

Claims (1)

[Claims] 1. A spring copper alloy for electrical equipment, characterized by containing 5 to 20% by weight of Ni, 1 to 8% by weight of Sn, and 0.02 to 1.0% by weight of B, with the remainder consisting of Cu and impurities.