JPH0456755A - Manufacture of phosphor bronze excellent in bendability - Google Patents

Abstract

PURPOSE:To improve the bendability of phosphor bronze by subjecting phosphor bronze in which Sn, P, S and Cu are specified to annealing at a prescribed temp. for prescribed time at least for one time. CONSTITUTION:Phosphor bronze constituted of, by weight, 0.5 to 9% Sn, 0.01 to 0.35% P, <=20ppm S and the balance Cu is melted. At the time of annealing this phosphor bronze, it is executed at 550 to 750 deg.C for >=30min at least for one time. Thus, its bendability can be improved and is used as the material for electric and electronic parts having a small bend radius.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing 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 has become essential. Phosphor bronze is originally a copper alloy with good bending workability, but recently there has been a demand for further improvements.

[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 Sn: 0.5 to 9.0 wt%, P
: 0.01 to 0.35 νt%, S: 20 ppm or less, or further Zn: 0.01 to 0.
Phosphor bronze containing 5 wt% and the balance consisting of Cu and unavoidable impurities is annealed at least once to 550 % by weight.
This is a method for producing phosphor bronze with excellent bending workability, characterized by carrying out the process at a temperature of ~750°C for 30 minutes or more.

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 wt%, P amount is 0.01 to 0.3
The reason for setting the Sn content to 5 wt% 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 workability will deteriorate. Furthermore, if P is less than 0.11wt%, the deoxidizing effect will not be sufficient and a healthy ingot cannot be obtained, whereas if it exceeds 0.35vt%, workability and stress corrosion cracking resistance will deteriorate. In general, alloyed phosphor bronzes having this composition range or partially containing a low Sn content are used as low tin phosphor bronzes.

The reason why the amount of S is 20 ppm 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 Cu2S 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. That is, by reducing the amount of S to 2 oppIm 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 almost no effect, and if it exceeds 0.5 wt%, the soldering properties will deteriorate and the stress corrosion cracking resistance will decrease.

Further, the reason why at least one annealing is performed at a temperature of 550 to 750°C for 30 minutes or more is that by performing such high-temperature and long-term annealing, the linear structure of Cuz S is divided, and the S
This is because unreacted Zn reacts with S and becomes ZnS which is not very harmful to bending workability. This annealing is 550~7
The reason for setting the temperature at 50℃ for 30 minutes or more is that below 550℃,
It takes too much time to divide the linear structure and generate ZnS, and if the temperature exceeds 750°C, the Cu-
This is because low-melting-point segregated substances such as P compounds become semi-molten, and the annealed material (coil) adheres closely.

In order to further reduce the amount of S, Mn, AI.

It is also effective to desulfurize the molten metal by adding metal elements such as Mg5NaSCaSCe and Zr5Cr in a total amount of 0.1 wt% or less during melting to improve bending workability.

As described above, the present inventors have found that bending workability can be improved by desulfurizing phosphor bronze, adding Zn, and performing high-temperature, long-term annealing at least once.

[Example] Phosphor bronze having the chemical composition shown in Table 1 was melted and cast in the atmosphere to obtain an ingot with a thickness of 20111 m.

These ingots were annealed at 500° C. for 1 hour and then cold rolled to a thickness of 1O2. Thereafter, it was annealed under each annealing condition shown in Table 1, and one side was shaved to a depth of 0.51. After cold rolling to a thickness of 2cm, it was annealed at a temperature of 350 to 500°C so that the crystal grains became IOμ days. After pickling No. 1 to 6 (
C5210 equivalent) is 0.33 ■ Thickness, No. 7 to 12
(corresponding to C5111) was cold rolled to a thickness of 0.38+am. At a temperature of 300 to 450℃, the crystal grains become 5μ■
After pickling, it was cold rolled to a total thickness of 0.25 ml, strain relief annealed at a temperature of 200 to 350°C, and pickled.

The tensile strength, elongation, and bending workability of each of the phosphor bronzes thus obtained were investigated. For bending workability, perform 1800 bends with a bending radius (-0,375m5) that is 1.5 times the board thickness, observe the appearance of the bent part with a microscope (50x magnification), and check the occurrence of cracks and rough skin conditions from A to D. It was evaluated by

In the examples of the present invention, No. 1 to No. 6 correspond to C5210.

It can be seen that Nos. 7 to 12 are phosphor bronzes equivalent to C5111 and have good bending workability.

On the other hand, the comparative example has the same tensile strength and elongation as the inventive example except for No. 13.17. In No. 13, since the amount of Sn was too large, edge cracks and surface cracks occurred during the first cold rolling, and the characteristic values etc. could not be evaluated. No, 14.
No. 16 had a high S content and was insufficiently annealed, so its bending workability was poor. In No. L5, the amount of P was too low, so many blowholes caused by oxygen occurred, and edge cracks occurred during cold rolling.

Furthermore, since the annealing is insufficient, the bending workability is not very good. In No. 17, the annealing temperature was too high, so the half-melted part during annealing became a flaw during cold rolling after annealing, and this flaw became the starting point for breakage during the tensile test and cracking during bending.
It has low elongation and poor bending workability.

Table 1 [Effects of the Invention] The present invention improves the bending workability of phosphor bronze by reducing the amount of S and annealing the phosphor bronze containing Zn at a high temperature and for a long time at least once. It is widely applied to phosphor bronze for electrical and electronic parts, which tend to be smaller.

Claims (2)

[Claims] (1) Sn: 0.5-9.0wt%, P: 0.01-0
．． Contains 35 wt%, S: 20 ppm or less, and the balance is Cu.
A method for producing phosphor bronze with excellent bending workability, characterized in that phosphor bronze containing unavoidable impurities is annealed at least once at a temperature of 550 to 750° C. for 30 minutes or more. (2) Sn: 0.5-9.0wt%, P: 0.01-0
．． 35wt%, Zn: 0.01-0.5wt%, S: 2
Phosphor bronze containing 0 ppm or less and the balance consisting of Cu and unavoidable impurities is annealed at least once at 55%
A method for producing phosphor bronze with excellent bending workability, characterized by carrying out the process at a temperature of 0 to 750°C for 30 minutes or more.