JPH042738A - Electrical part, copper alloy for it, and manufacture thereof - Google Patents

Abstract

PURPOSE: To produce a high strength copper base alloy excellent in spring characteristics by subjecting a cast ingot composed of a copper base alloy having a specified compsn. to hot-rolling, heat treatment, cold rolling and low temp. stress relieving annealing treatment under specified conditions in succession.

CONSTITUTION: A copper base alloy contg., by weight, 20 to 27% Zn, 2.0 to 7.0% Al, 0.5 to 5.0% Ni, 0.1 to 1.0% Si, 0.01 to 0.5% Zr, and the balance Cu is melted at 1,100 to 1,200°C in an induction furnace in a reducing atmosphere and is poured into a die to form into a cast ingot. This ingot is homogenized at 850 to 900°C for 1 to 6hr, is subjected to hot rolling at 800 to 850°C and is subjected to heat treatment at 550 to 660°C for 1 to 5hr to produce single FCCα phases. Next, its thickness is reduced by ≥50% by cold rolling, furthermore, in the process of the cold rolling, annealing is executed at 450 to 500°C for 1 to 3hr to form fine grain size, and after final cold rolling, low temp. stress relieving annealing is executed at 200 to 300°C for 30 to 60min to impart excellent spring characteristics thereto.

COPYRIGHT: (C)1992,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to copper alloys for electrical and electronic components, and more particularly to new and improved copper alloys with good spring properties for connector and spring applications. The present invention relates to copper alloys and methods for producing such new and improved copper alloys.

[Prior art and problems to be solved by the invention] Materials used for electrical and electronic components such as connectors, springs, relays, contacts, and switches have high strength and good spring characteristics. This is required. High-strength copper-based alloys are currently in use, with the most widely used copper-based metal being phosphor bronze (CDA510.0DA511
) and beryllium copper alloy (CDA172°CDA175
).

Since phosphor bronze contains a relatively high content of tin (5% by weight), the manufacturing process is difficult due to the segregation of tin during solidification. In addition, the cost of phosphor bronze is high due to the complex manufacturing process as well as the high content of expensive tin components.

Segregation of the tin component must be minimized during solidification and rolling conditions must be carefully controlled to avoid cracking during thermomechanical processing. However, the mechanical properties of phosphor bronze (CDA510) are inferior to those of beryllium copper alloys for electrical component applications.

Although beryllium copper alloys have excellent mechanical properties along with good electrical and thermal conductivity, the cost of these alloys is very high due to their beryllium content. Also, beryllium alloys pose health problems when used, and due to the presence of beryllium, all melting, crushing,
Appropriate safety measures must be taken for machining and welding operations.

One prior art copper alloy is disclosed in JP-A-52-5219. However, this particular alloy does not exhibit an increase in tensile strength and ductility. A second prior art copper alloy is disclosed in JP-A-80-59015. This alloy exhibits increased tensile strength, but requires the addition of phosphorus. Finally, a third prior art copper alloy is disclosed in JP-A-59-25935.

This alloy has high wear resistance rather than increased tensile strength, but requires the use of zinc, zirconium and iron additives.

It is an object of the present invention to develop a new low-cost, high-performance copper alloy that has high strength and spring properties, but does not require the use of expensive alloying components.

[Means to solve the problem]

According to the present invention, in order to achieve the above object, zinc 20
-27% by weight, aluminum 2.0-5.0% by weight, nickel 0.5-5.0% by weight, silicon 0.1-1.0% by weight, zirconium 0°01-0.5% by weight, and the balance A copper alloy comprising copper having high strength and excellent spring properties is provided.

Furthermore, according to the present invention, (A) 20 to 27% by weight of zinc;
Aluminum 2.0~5.0% by weight, Nickel 0.5~
A copper-based alloy consisting of 5.0% by weight, 0.1 to 1.0% by weight of silicon, 0.01 to 065% by weight of zirconium, and the balance copper was melted in an induction furnace under a reducing atmosphere to a melting temperature of 11% by weight.
Molten metal is injected into the mold at a temperature of 00 to 1200℃, (
B) Homogenize at 850-900°C for 1-6 hours, 800-900°C
Hot rolled at 850°C, (C) Heat treated at 550 to 660°C for 1 to 5 hours after hot rolling to produce a single FCCα phase, (D) Thickness after hot rolling is 50°C. (E) During the cold rolling, annealing is performed at 450 to 500°C for 1 to 3 hours to produce a very small grain size. F) Copper-based alloy with high strength and excellent spring properties, which consists of each step of performing low-temperature stress relief annealing treatment at 200 to 300°C for 30 to 60 minutes to produce excellent spring properties after the final cold rolling process. A manufacturing method is provided.

[Actions, effects and modes of the invention]

Advantageously, by using the present invention, the use of expensive alloying components such as tin and beryllium can be completely omitted. Instead, large amounts of inexpensive alloying components such as zinc and aluminum are added as the main alloying component to reduce cost. Additionally, small amounts of microalloy components (1% by weight or less) such as silicon and zirconium are added to improve grain size. Importantly, optimal thermomechanical manufacturing methods are employed to obtain superior strength and ductility due to grain size improvement, and superior spring properties are obtained by applying suitable heat treatments.

When utilizing the present invention to produce strip or sheet products, cold rolling is employed. To enable cold rolling, it is desirable to use a face-centered cubic (FCC) structure for the base matrix. To enhance the strength of the final product, some solid solution hardening components can be added to the FCC matrix without forming a second phase, such as body-centered cubic (BCC) in copper-zinc systems. can. Very high strength can be obtained by combining various strengthening mechanisms such as viscosity improvement, cold rolling, and solid solution hardening. Good spring properties can be achieved by stress relief heat treatment after the final cold rolling process.

Zn20-27% by weight, Ai) 2-5% by weight, NiO,
5 to 5.0 wt%, Si0.1 to 1.0 wt%, and Z
A copper-based alloy consisting of r0.01-0.5% by weight is melted in an induction furnace. The cast ingot was rolled at 850 ml before hot rolling.
Homogenization heat treatment at ~900°C for 1-6 hours. For hot rolling, the ingot slab is reheated to 800-850" and then hot rolled using a reversible hot rolling mill. The hot rolled plate is rolled to the desired shape before cold rolling. F
Annealed at 550-660°C for 1-5 hours to produce CCα phase. The annealed hot rolled strip is then cold rolled using a reversible cold rolling mill.

The copper alloy of the present invention showed good suitability for secondary forming in hot rolling as well as cold rolling. During the cold rolling process, the strips were annealed at 450-500 °C for 1-3 hours after the thickness was reduced by about 50%. The thermomechanical treatment creates a fine grain structure for increased strength and ductility of the alloy. The alloy can also be used in cold rolled strip or rolled at 30-60°C at 200-300°C to increase spring properties.
It can also be subjected to stress relief heat treatment.

Alloy Ingredients and Limitations: Zinc addition (20-27% by weight) was made as the main solid solution hardener to reduce the cost of the invention alloy. Above 27% by weight zinc, a two-phase transition can occur, namely the alpha phase FCC and the BCC beta phase, both of which are detrimental to ductility. On the other hand, the zinc content is 20% by weight.
If it is less than that, the alloy will not exhibit sufficient strength.

Ag is added to the alloy of the invention (2-5% by weight).

It has been found that when the amount of Al1 exceeds 5% by weight, cold rolling becomes difficult and ductility becomes low.

Conversely, if the amount of AII is less than 2% by weight, the desired high strength cannot be obtained.

The addition of Ni (0.5-5% by weight) was made to improve the ductility of the alloy. Ni is an FCCα phase stabilizing component and expands the solubility of Aff in the Cu-Zn-Al-X system. If the Ni content is less than 0.5% by weight, the improvement in ductility will not be sufficient, while if the Ni content exceeds 5% by weight, the cost of the resulting alloy will become uneconomical.

Addition of Si (0.1-1.0% by weight) was made to improve grain size and increase strength. The amount of Si is 0.
If it was less than 1% by weight, fine particle size or sufficient strength could not be obtained. On the other hand, if the amount of Si exceeded 1% by weight, it was detrimental to the improvement of ductility.

The addition of Zr (0.01-0.5 wt%) was very important to further reduce the grain size in order to achieve high strength together with good ductility.

By adding Zr and St simultaneously, a very small particle size with high strength and forming suitability was obtained. It has been found that if the Zr content is less than 0.01% by weight, grain size improvement is not sufficient, while if the Zr content exceeds 0.5% by weight, possible grain boundary segregation of the α phase occurs.

Manufacturing process: Zn 20-27% by weight, A472-5% by weight, Ni
The copper alloy of the present invention, consisting of O, 5-5.0% by weight, SiO, 1-1.0% by weight and ZrO, 01-0.5% by weight, is melted in an induction furnace under a reducing atmosphere. . Commercial pure raw materials of electrolytic copper, zinc, aluminum and nickel are used.

Pure silicon and zirconium are added.

The molten metal is poured into the mold when the melting temperature is 1100-1200°C. The cast ingot is heated to 85% before hot rolling.
Homogenize at 0-900°C for 1-6 hours. 800-85
After reheating the ingot at 0° C. for 1 to 2 hours, the ingot is hot rolled using a reversible hot rolling mill. When the desired thickness is reached, the ingot is cooled to room temperature. In order to obtain a homogeneous structure with equilibrium in the α-phase, the hot-rolled plate was annealed at 550-660 °C for 1-5 hours,
Continue to cool down. The annealed plate is then subjected to a cold rolling process without cracking,
This shows good cold rolling formability for the alloy of the invention. After about 70% reduction by cold rolling, the cold strip is annealed at 450-500° C. for 1-3 hours to further reduce the thickness.

The final cold-rolled strip is exposed for application removal at 200-300° C. for 0.5-1 hour to increase spring properties.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 An alloy having the chemical composition shown in Table 1 (No. 1.2°3.4.
5) was melted using a high frequency induction furnace.

Liquid metal at 1150℃ 50 x 50 x 130
It was poured into a mold having dimensions of mm.

The ingot was homogenized at 900°C for 1 hour and hot rolled at 850°C. The hot rolled plate was annealed at 550°C for 5 hours. Cold rolling the annealed plate 5
Reduced by 0%.

An intermediate annealing treatment was performed at 500'C for 1 hour during the cold rolling process. The final plate was annealed at 250”C for 1 hour to enhance its spring properties.

The obtained alloy No. 5 of the present invention (“PM” in Fig. 3)
The mechanical properties of C-707'') were compared with those of phosphor bronze CDA310 and Cu-Be alloys CDA175 and CDA172. The results are shown in Figure 3.
It has greater strength than DA310 but is inferior to CDA-172. Due to the final annealing treatment on the cold-rolled sheet, the spring characteristic value decreased from 33 kg/mm2 to 80 kg/mm2.
Increases to m+g 2.

Example 2 The alloy shown in Table 2 (No. 6.7) was melted and cast in the same manner as in Example 1.

Being able is essential.

By adding Si and Zr simultaneously, as shown in Fig. 1 (C)
As shown in Figure 2, the grain size was further improved and high strength was obtained along with good ductility.

Figure 2 shows the dislocation substructure developed by cold rolling.

Dislocation substructure is essential for high strength.

Example 3 Two alloys having the compositions shown in Table 4 were melted in an induction furnace and cast into a rectangular mold.

The ingot was homogenized at 850°C for 6 hours.

The homogenized ingot was hot rolled at 800°C. The hot rolled plates were annealed under two different conditions. The first condition is 550°C to obtain a complete FCCα phase.
The second condition was 700° C. for 1 hour to obtain a mixture of α and β phases. The annealed plates were cold rolled to reduce the complete α-phase plates and the binary α and β-phase plates by 50%. Cold cracking occurred for the α+β phase material when a 50% reduction was applied, but no cold rolling cracking occurred for the α phase material for the same reduction (50%). Therefore, a 35% reduction was applied to the α+β phase material. The final rolled sheet was annealed at 220° C. for 1 hour. The mechanical properties of the α+β phase material (35% reduction) are summarized in Table-3. When compared with that of the complete α phase (see Table 2), the mechanical properties of the α+β phase material are inferior to those of the α phase material. Therefore, the post-annealing treatment after hot rolling caused complete FCCα phase transition, and after homogenization treatment at 850°C for 5 hours, the ingot was
After reheating to 0°C, hot rolling was performed. The hot-rolled plates were annealed at 600 and 650 °C for 3 and 1 h, respectively, to obtain the thermodynamic equilibrium phase of the FCCα phase.

The annealed plate is cold rolled in several steps.
% and 70%), the thickness decreased during the above steps.

The first cold rolled strip was annealed at 500° C. and 450° C. for 1.5 hours and 2.5 hours, respectively, and then subjected to second cold rolling.

To investigate the effect of low temperature annealing treatment on the mechanical properties, the final cold rolled strip was
Annealed at ℃ for 30 and 40 minutes, respectively. The results are summarized in Table-4.

[Brief explanation of drawings]

Figure 1 (A), (B) and (C) are Cu-232n-
3 is an optical micrograph of an alloy structure showing the result of adding 81 and Zr to an alloy consisting of 3,4AIJ-INi. Figure 2 shows the Cu-23Zn-3,4 dislocation substructure.
1 is a transmission electron micrograph of a cold rolled strip of an alloy consisting of All-INi-0,3S i-0,IZr. Figure 3 shows a typical composition Cu-23Zn-3,4AΩ-INi-0,3S, designated as PMC-707.
1 is a graph showing the yield strength and tensile strength of the i-0, IZr inventive alloy in comparison to other high performance alloys, phosphor bronze CDA310, beryllium copper CDA175 and CDA172 alloys. Applicant Boongsan, Corporation Agent
Patent attorney Masaaki Yonehara

Claims (2)

[Claims] (1) Zinc 20-27% by weight, aluminum 2.0-5%
．． 0% by weight, 0.5-5.0% by weight of nickel, 0.0% of silicon.
A copper alloy with high strength and excellent spring properties consisting of 1-1.0% by weight of zirconium, 0.01-0.5% by weight of zirconium and the balance copper. (2) (A) 20-27% by weight of zinc, aluminum 2.
0-5.0% by weight, 0.5-5.0% by weight of nickel, 0.1-1.0% by weight of silicon, 0.01-0.0% by weight of zirconium.
A copper-based alloy consisting of 5% by weight and the balance copper is melted in an induction furnace under a reducing atmosphere, and the melting temperature is 1100-1200°C.
(B) Homogenize at 850-900℃ for 1-6 hours,
(C) After hot rolling, heat treatment is performed at 550-660°C for 1-5 hours to produce a single FCCα phase; (D) The thickness after hot rolling is (E) during the cold rolling, annealing is performed at 450 to 500°C for 1 to 3 hours to produce a very small grain size; (F) A copper base with high strength and excellent spring properties, which consists of each step of performing low-temperature stress relief annealing treatment at 200 to 300°C for 30 to 60 minutes to produce excellent spring properties after the final cold rolling process. Alloy manufacturing method.