JPH0456739A - Phosphor bronze excellent in bendability - Google Patents

Abstract

PURPOSE:To stably manufacture a phosphor bronze sheet excellent in bendability, at the time of manufacturing phosphor bronze by reducing the content of S, or furthermore, adding Zn and refining its grain size by cold rolling and heat treatment. CONSTITUTION:At the time of manufacturing phosphor bronze constituted of, by weight, 0.5 to 9.0% Sn, 0.01 to 0.35% P and the balance Cu, the content of S for reducing the content of Cu2S damaging its bendability to <=20ppm and, according to necessity, 0.01 to 0.5% Zn is added thereto to convert harmful Cu2S into harmless ZnS. Furthermore, the slab of this phosphor bronze is repeatedly subjected to cold rolling and annealing and is worked into a sheet material having 1 to 10mum grain size, by which the phosphor bronze sheet having more excellent bendability than that of a conventional one can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to phosphor bronze, which is widely used as electrical and electronic components.

[Prior Art] Phosphor bronze is a typical copper alloy that has been used for a long time as an electrical and electronic component. Materials for electrical and electronic components such as connector lead frames are required not only to have high strength and high conductivity, but also to have good bending workability.

Particularly recently, as parts have become smaller, the bending radius of materials has also become smaller, and materials for electrical and electronic parts are
Good bending workability is essential. Phosphor bronze is originally a copper alloy with good bending workability.
Recently, further improvements have been required.

[Problems to be Solved by the Invention] In view of the above-mentioned prior art, the present invention aims to further improve the bending workability of phosphor bronze.

[Means for Solving the Problems] The present invention provides S n of 0.5 to 9. Owt%, P
: 0.01 to 0.35 wt%, S: 20 ppm or less, or further Zn: 0.01 to 0.
It is a phosphor bronze with excellent bending workability, containing 5 wt% of Cu and the balance being Cu and unavoidable impurities. In particular, it is preferable that the average crystal grain size is in the range of 1 to 10 μm.

The strength of phosphor bronze is improved by solid solution of Sn in Cu, and P
This method improves manufacturability by deoxidizing S
N amount is 0.5 to 9.0 νt%, P amount is 06 inches to OJ5w
The reason why Sn is set at t% is that if the Sn content is less than 0.5 wt%, no significant improvement in strength can be expected, whereas if it exceeds 9.0 wt%, the manufacturability and processability will deteriorate. Also, P is 0.0
If it is less than 1wt%, the deoxidizing effect will not be sufficient and a sound ingot will not be obtained.On the other hand, if it exceeds 0.35wt%, the workability,
This is because the stress corrosion cracking resistance deteriorates, and generally alloyed phosphor bronzes having this composition range or some of them are used as low tin phosphor bronzes.

The reason why the amount of S is 209 p■ or less is to improve bending workability. S is contained in raw materials (oil in scrap), charcoal, etc. during melting, and a certain amount of S is unavoidably mixed. The mixed S exists as CuzS in phosphor bronze.

When this Cu2S is cold rolled, it is elongated and becomes a linear shape, which tends to become a starting point for cracking when bending is performed. In other words, by reducing the amount of S to 20 ppm or less,
The bending workability of phosphor bronze can be improved.

The addition of Zn converts S into Cu2S, which is harmful to bending workability.
This is to change the ZnS from ZnS to less harmful ZnS, which is easily divided during annealing, does not form a long linear structure after cold working, and does not adversely affect the bending workability of the phosphor bronze. to make it good, but the amount is 0.01
The reason for setting the content to 0.5 wt% is that if it is less than 0.01 wt%, there will be little effect, and if it exceeds 0.5 vt%, the soldering properties will deteriorate and the stress corrosion cracking resistance will decrease.

The reason why the average crystal grain size of the product is set to 1 to 10 μm is to improve bending workability. It is practically difficult to obtain a uniform recrystallized structure of less than 1 μm, and if unrecrystallized portions remain, bending workability will be significantly impaired. Moreover, if the thickness exceeds lOμ, roughness will occur during bending.

Also, in order to reduce the amount of S, Mn5Al.

It is also effective to desulfurize the molten metal by adding metal elements such as Mg, Na5CaSCe, Zr, and Cr in a total amount of 0.1 νt% or less during melting to improve bending workability.

As described above, the present inventors desulfurize phosphor bronze, add Zn, and perform high-temperature long-term annealing at least once after cold rolling, so that the average grain size of the product is 1 to 10μ■. It has been found that bending workability can be significantly improved by this.

[Example] Phosphor bronze having the chemical composition shown in Table 1 was melted and cast in the atmosphere, and cold rolling and annealing were repeated to obtain a cold rolled plate having a thickness of 0.25 mm. These phosphor bronze plates were appropriately strain-relieved annealed and their average crystal grain size, tensile strength, elongation, and bending workability were investigated. Bending workability is determined by bending radius 1.5 times the plate thickness (
- 0.375 mm), the appearance of the bent part was observed under a microscope (50x magnification), and the occurrence of cracks and rough skin were evaluated using A-D.

Among the alloys of the present invention, No. 1 to 6 correspond to C5210, No.
7 to 12 are phosphor bronze equivalent to C5111.

As can be seen from Table 1, the alloy of the present invention reduces the amount of S, makes the crystal grains fine, and further adds Zn.
It can be seen that it has high strength and excellent bending workability. On the other hand, the comparative alloys have tensile strength and elongation equivalent to those of the invention alloy, but Nos. 13 to 16 have a high S content and have poor bending workability.

Table 1 is available, and it is widely applied to phosphor bronze for electrical and electronic parts, which tend to be smaller.

Claims (3)

[Claims] (1) Sn: 0.5-9.0wt%, P: 0.01-0
．． Contains 35 wt%, S: 20 ppm or less, and the balance is Cu.
Phosphor bronze with excellent bending workability, which is made up of unavoidable impurities. (2) Sn: 0.5-9.0wt%, P: 0.01-0
．． 35wt%, Zn: 0.01-0.5wt%, S: 2
Phosphor bronze with excellent bending workability, containing 0 ppm or less, with the balance being Cu and unavoidable impurities. (3) The phosphor bronze according to claim (1) or (2), which has an average crystal grain size of 1 to 10 μm and has excellent bending workability.