JPH06248375A - High strength and conductive copper alloy - Google Patents

Abstract

PURPOSE:To develop a copper allay for a spring having high strength and high electrical conductivity by specifying the compsn. constituted of Ti, Cr, Zr, Fe, Ni and Cu. CONSTITUTION:This is a copper alloy for a spring contg., by weight, 2.0 to 5.O% Ti, 0.01 to 0.6% Cr, 0.01 to 0.2%. Zr, 0.01 to 0.3% Fe and 0.01 to 0.3% Ni, and the balance Cu with inevitable impurities. By adding Cr and Zr to Cu-Ti alloy series, its strength is improved, and by adding Fe and Ni, mainly, its electrical conductivity is improved. This copper alloy is subjected to hot rolling, cold rolling and solution treatment, is again subjected to cold rolling and is subjected to aging treatment at 350 to 500 deg.C, by which its characteristics of excellent strength and electrical conductivity can be obtd. without deteriorating its elongation and workability.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a high strength and high conductivity copper alloy. As a use of the present invention, for example, it is suitable for use of a conductive spring material such as a connector, a relay and a switch.

[0002]

[Prior Art and Problems] Conventionally, connectors, relays,
A copper alloy such as phosphor bronze, nickel silver, titanium copper, and beryllium copper is used as a conductive spring material such as a switch. Beryllium copper has excellent properties in terms of strength and conductivity, but has the drawback of being expensive because it is highly toxic to beryllium and requires special manufacturing equipment. ing. Further, as a material excellent in stress relaxation characteristics, which is an important characteristic of spring materials, Cu called titanium copper is used.
There is a -Ti alloy, and particularly for a conductive spring material, a Cu-Ti alloy containing 2.0 to 5.0% of Ti is used. The Cu-Ti alloy has a remarkable age hardening property and has a strength comparable to that of beryllium copper, but has a drawback that its conductivity is slightly low. Also, to increase strength, T
Increasing the content of i causes a problem that conductivity decreases. In recent years, as electronic devices have become smaller and lighter, demands for smaller electronic components and thinner walls have become stronger. Therefore, it is also necessary to improve the properties such as strength and conductivity of the conductive spring material. However, Cu-
In an age-hardenable alloy such as a Ti alloy, when the aging treatment is performed at high temperature for a long time in order to increase the conductivity, there is a problem that the strength deteriorates due to overaging.

[0003]

[Methods for solving the problems] In order to solve these problems, a study was conducted to improve the properties of the Cu-Ti alloy, and an alloy having higher strength and higher conductivity than the Cu-Ti alloy was developed. We were able to. By adding an appropriate amount of Cr and Zr to the Cu-Ti alloy, the strength could be improved without deteriorating the characteristics such as conductivity and workability. By adding appropriate amounts of Fe and Ni to the Cu-Ti alloy, it was possible to improve the conductivity without lowering the strength. That is, according to the present invention, Ti 2.0 to 5.
0 wt%, Cr 0.01 to 0.6 wt%, Zr 0.
01-0.2 wt%, Fe 0.01-0.3 wt%,
A high-strength and high-conductivity copper alloy containing 0.01 to 0.3 wt% of Ni and the balance being Cu and inevitable impurities.

[0004]

DETAILED DESCRIPTION OF THE INVENTION A Cu—Ti alloy containing Ti in an amount of 2.0 to 5.0 wt% is rapidly cooled after solution treatment and is subjected to an aging treatment to form fine precipitates aligned with the mother phase. hand,
It is an age precipitation hardening type copper alloy that brings remarkable age hardening properties and is excellent in strength and spring properties. The present invention is an age precipitation hardening type copper alloy having high strength and high conductivity, in which the strength and conductivity of the Cu-Ti alloy system are further improved. In general,
In the age precipitation hardening type alloy, when the solution treatment is carried out at high temperature or for a long time, the crystal grains become coarse, and the strength is lowered and the workability is deteriorated. On the contrary, if the solution treatment temperature is too low or the treatment time is too short, the solution treatment cannot be performed sufficiently. Further, if the aging treatment is carried out at a high temperature or if the aging treatment is carried out for a long time, the conductivity is improved, but if it is overaged, the strength is lowered. For this reason, it is necessary to make the conditions of the solution treatment and the aging treatment appropriate according to the characteristics of the intended alloy system, but these conditions are almost determined by the composition of the alloy and cannot be freely controlled.

Cu-Cr alloys and Cu-Zr alloys are
Like the Cu-Ti alloy, it is an age precipitation hardening alloy.
When Cr and Zr are added to the Cu-Ti alloy, Cr and Zr
Also causes age precipitation hardening, and the strength is improved as compared with the Cu-Ti alloy. In addition, an appropriate amount of Cr for the Cu-Ti alloy
Is effective in suppressing coarsening of crystal grains during the solution treatment. Furthermore, adding an appropriate amount of Zr to the Cu-Ti alloy has the effect of suppressing grain boundary precipitation during aging treatment and suppressing softening due to overaging. When an appropriate amount of Fe and Ni are added to the Cu-Ti alloy,
Aging treatment at high temperature for a long time becomes possible, and conductivity can be improved without lowering strength. this is,
Since the aging treatment condition required for aging precipitation of the compound containing Fe or Ni is higher temperature and longer time than in the case of Cu-Ti alloy, the aging treatment is performed again under the condition that the Cu-Ti alloy softens due to overaging. This is because the precipitation causes hardening. Further, by simultaneously adding Fe and Ni, the effect of preventing the strength reduction due to overaging becomes remarkable due to the difference in the time required for the precipitation.

Next, the composition range of the alloy system of the present invention will be described. In the present invention, the content of Ti is 2.0 to
The reason for setting 5.0 wt% is that the content of Ti is 2.0 wt.
If it is less than%, sufficient age precipitation hardening does not occur, so that the strength required for the spring material cannot be obtained. Also, Ti
This is because if the content of Al exceeds 5.0 wt%, workability and conductivity are significantly deteriorated. The content of Cr is 0.01 to
0.6 wt% and Zr content of 0.01 to 0.2 w
The reason for setting t% is that if the content of Cr or Zr is less than 0.01%, the effect of suppressing grain boundary type precipitation and the effect of refining crystal grains cannot be obtained, and the strength cannot be improved. This is because. If the Cr content exceeds 0.6 wt% or if the Zr content exceeds 0.2 wt%, the limit amount of Cr or Zr that can form a solid solution in copper is exceeded. This is because Cr, Zr, or a compound containing Cr, Zr has already precipitated, and this precipitate not only contributes to age precipitation hardening, but also decreases elongation and deteriorates workability. Fe and Ni
The content of each of 0.01 to 0.3 wt% is because the Fe or Ni content is less than 0.01%, the aging precipitation effect by the compound containing Fe or Ni cannot be obtained, and the strength is This is because the conductivity cannot be improved without lowering the conductivity. When the content of Fe or Ni exceeds 0.3 wt%, it is combined with Ti during melting and casting, and a compound containing Ti and Fe or Ni is precipitated, and this precipitate is not solutionized by homogenizing annealing or solution treatment. This is because not only it does not contribute to age precipitation hardening, but also the amount of Ti to be solution-treated is reduced and the strength is lowered. Further, since this precipitate is harder than the parent phase at room temperature, it lowers elongation, deteriorates cold workability, and causes cracking. Therefore, the content of Fe or Ni should be 0.3 wt% or less. Do not cross. The raw material used is a pure metal or a mother alloy, but it is desirable that the impurity element is small. In the alloy of the present invention, Ti and Zr
It is desirable to use a raw material containing a small amount of gas components such as oxygen because it contains such an active metal.

Next, the heat treatment conditions will be described. Since the alloy component of the present invention contains an active metal such as Ti or Zr that is particularly likely to combine with oxygen, the alloy is melted in vacuum or in an inert gas. Since the ingot obtained by melting the alloy and casting it in a mold causes segregation during solidification, it is held at a temperature of 800 to 950 ° C., homogenized annealing is performed, and then hot rolling is performed. If the homogenization annealing temperature is less than 800 ° C, the temperature is too low to be sufficiently homogenized. The solution treatment is carried out by holding the temperature at 800 to 950 ° C. to form a single phase, and then putting it in water to cool it.
Quench to form a supersaturated solid solution. Solution treatment temperature is 8
If the temperature is lower than 00 ° C, the temperature is too low to allow the alloying elements to be sufficiently solid-dissolved, and it may not be possible to form a single phase. The alloy elements that cannot be solid-dissolved become precipitates, which causes a decrease in elongation and deterioration of workability. Further, if the solution treatment temperature exceeds 950 ° C., the crystal grains become coarse, so that the strength decreases and the workability deteriorates. The aging treatment was performed by cold rolling the supersaturated solid solution obtained by the solution treatment and then 350
Hold at a temperature of ~ 500 ° C. When aging treatment is performed,
Although the strength and the electric conductivity gradually increase, if the aging treatment is performed for a longer time than necessary, overaging causes the strength to decrease, so that an appropriate condition must be selected. Since the appropriate aging temperature and time differ depending on the composition, a test to find appropriate conditions for each composition is performed. When the temperature of the aging treatment exceeds 500 ° C., the solubility of the alloying element in solid solution in copper becomes large, and the strength and the conductivity decrease. Further, if the aging temperature is lower than 350 ° C., the aging treatment is possible, but since the treatment for an extremely long time is required, the productivity is deteriorated and it is industrially meaningless.

Hereinafter, examples of the present invention will be described.

[Examples] The alloy composition of the present invention was blended, vacuum melted in a graphite crucible using a high frequency vacuum melting furnace, and then cast in a mold,
We made an ingot of 30mm x 80mm x 150mm. The chemical composition is shown in Table 1. After chamfering the ingot, 90
After heating to 0 ° C and homogenizing annealing, hot rolling is performed to obtain a width of 8
A plate material having a thickness of 0 mm and a thickness of 7 mm was used and the surface was ground to remove defects such as scale on the surface. This was cold-rolled to a thickness of 1.5 mm, solution-treated at 850 ° C., and then rapidly cooled in water. Then, it was cold-rolled to a thickness of 0.6 mm, solution-treated again at 850 ° C., and then rapidly cooled in water. This is cold-rolled with a final working ratio of 50%, finished into a 0.3 mm plate, and subjected to an aging treatment in vacuum at a temperature in the range of 350 to 500 ° C. under conditions that maximize age hardening. It was The aging treatment conditions are shown in Table 2. The tensile strength, elongation, Vickers hardness, and conductivity of the plate material thus obtained were measured. Table 2 shows the results of measuring the aging treatment conditions and characteristics. The workability shown in Table 2 is indicated by x when cracks occurred on the side during cold rolling, and by o when cracks did not occur on the side. In addition, the results of comparative examples made in the same manner are shown in Tables 1 and 2.

[Table 1]

[Table 2]

As is clear from Tables 1 and 2, the alloy composition of the present invention has a tensile strength of 100 kg / mm ² or more and an electric conductivity of 13% IACS under the conditions that maximize the age hardening. From the above, it is clear that the alloy has high strength and high conductivity as compared with the case of the comparative alloy composition. In addition, the elongation is as large as 11.7% or more despite the high strength. Alloys containing no Fe and Ni, such as alloy numbers 7 and 8, have a conductivity of 10-11% IAC.
It can be seen that the conductivity is poor under the condition where S is low and the age hardening is maximum. Further, as in Alloy Nos. 9 and 10, when either Fe or Ni is not contained, the effect of suppressing the strength reduction due to overaging is smaller than that of the alloys of the present invention, and the high strength due to the synergistic effect of Fe and Ni. It becomes possible to keep.

Alloy No. 3 of the present invention and Alloy No. 11
Comparing the comparative alloys of No. 11 and No. 11, since the Cr content is less than 0.01 wt%, the tensile strength is 6 kg.
As low as / mm ² . Further, it is clear that when the Ti content is less than 2.0 wt% as in Alloy No. 14, the tensile strength is remarkably reduced and the spring material is not suitable for use. In the alloy composition of the present invention, the elongation is 11.7% in all cases.
As described above, when the composition of Fe or Ni exceeds 0.3 wt% as in Alloy Nos. 9, 10, 12, and 13, the elongation decreases to 5.7% or less. This is because if the Fe or Ni content exceeds 0.3 wt%, Ti and F
This is because a compound containing e or Ni is deposited. With the alloy composition of the present invention, cracking did not occur during cold rolling. As is clear from alloy numbers 10 and 13, Fe
Alternatively, it can be seen that if the Ni composition exceeds 0.3 wt%, cracks occur on the side during cold rolling and workability deteriorates.

[0011]

According to the present invention, it is possible to obtain a high-strength and high-conductivity copper alloy suitable for a conductive spring material, which has excellent strength and conductivity without impairing elongation and workability.

Claims (1)

[Claims] 1. Ti 2.0-5.0 wt%, Cr
0.01-0.6 wt%, Zr 0.01-0.2 wt
%, Fe 0.01 to 0.3 wt%, Ni 0.01 to
A high-strength and high-conductivity copper alloy containing 0.3 wt% and the balance being Cu and unavoidable impurities.