JP5522692B2 - High strength copper alloy forging - Google Patents

Description

  The present invention relates to a high-strength copper alloy forging material suitable for forging products such as resin injection mold materials.

Conventionally, copper alloys such as brass (Cu—Zn), bronze (Cu—Sn), Be copper and Corson alloy (Cu—Ni—Si) have been used as alloys having excellent conductivity and thermal conductivity. Yes. In particular, Be copper and Corson alloy are used for resin injection mold materials and aircraft members that require heat conduction and strength and hardness. However, the above-mentioned Be copper is concerned about the toxicity of dust generated during melting and processing, and an alternative material is required. Further, the Corson alloy is required to have higher thermal conductivity, higher strength, and higher hardness.
In general, Cu alloys are liable to crack during forging or heat treatment, and it is required to improve ductility in addition to hot workability.

  In recent years, copper alloys obtained by adding Mg, Sn, Ti, Zr, Al, Mn, etc. to a Cu—Ni—Si based copper alloy as a measure to increase the strength and improve the bending workability with a copper alloy foil strip. It has been proposed (see Patent Documents 1 to 5). Mg and Sn are dissolved in the matrix to improve the strength. Ti, Zr, Al, and Mn have a strong affinity for sulfur, so they form a compound with sulfur, reducing the segregation of sulfides to the grain boundaries that cause hot work cracking.

  The copper alloy foil strips as shown in Patent Documents 2, 3, and 5 are added with Sn, Mn, Zr, and the like, and before and after the solution treatment and the aging treatment, hot rolling, cold rolling and hot rolling. By repeatedly performing drawing and cold drawing, it has bending workability and strength exceeding conventional copper alloy foil strips.

JP 2006-9108 A JP 2008-196042 A JP 2008-223136 A JP 2008-266787 A JP 2010-106363 A

However, when manufacturing a Cu alloy molded product, since it is mainly formed by hot forging, when rolling and drawing processes such as those performed in foil strip manufacturing cannot be employed, Patent Documents 2, 3, and 5 are shown. Even if a forged molded product is manufactured with various components, high strength cannot be obtained.
In order to obtain high strength, an increase in the amount of Ni and Si is effective, but the thermal conductivity and hot workability are reduced. Moreover, the crystallized substance produced | generated during solidification and the precipitate produced | generated during heat processing increase, and the ductility after heat processing falls.

  The present invention has been made against the background of the above circumstances, and can be used for forged molded articles such as resin injection mold materials, and can obtain characteristics of high hardness, high strength, high ductility, and high thermal conductivity. It aims at providing the high strength copper alloy forging material which can be performed.

In order to solve the above problems, the present invention contains a suitable amount of Zr having an effect of increasing the ductility by suppressing the precipitation of Ni ₂ Si to the grain boundary in the Cu—Ni—Si based copper alloy, To obtain a material having the effect of increasing the density of fine precipitates and having characteristics of high hardness, high strength, and high thermal conductivity by containing an appropriate amount of P that forms a compound with Ni, Si and Zr. Is possible.

That is, among the high-strength copper alloy forgings of the present invention, the first present invention is mass%, Ni: 3 to 7.2%, Si: 0.7 to 1.8%, Zr: 0.02 to 0.35% P: containing from 0.002 to 0.05%, balance Ri Do Cu and inevitable impurities, 0.2% proof stress above 650 MPa, elongation of 5% or more, conductivity is 30% It is more than IACS .

The high-strength copper alloy forging material of the second aspect of the present invention is, in mass%, Ni: 3 to 7.2%, Si: 0.7 to 1.8%, Zr: 0.02 to 0.35%, P : containing 0.002 to 0.05%, further, Cr, Mn, and containing 1.5% or less in total of one or more of Zn, Ri Do the balance is Cu and inevitable impurities, 0. 2% yield strength is 650 MPa or more, elongation is 5% or more, and conductivity is 30% IACS or more .

  The reasons for limiting the composition of each component in the present invention will be described below. In addition, all the content of the following component is shown by the mass%.

Ni: 3 to 7.2%
Si: 0.7-1.8%
Ni and Si form precipitation particles of intermetallic compounds mainly composed of Ni ₂ Si in which Ni and Si are fine by performing an aging treatment, and remarkably increase the strength of the alloy. Further, with the precipitation of Ni ₂ Si in the aging treatment, the conductivity is improved and the thermal conductivity is improved. However, when the Ni concentration is less than 3% and the Si concentration is less than 0.7%, the desired strength cannot be obtained. Further, when the Ni concentration exceeds 7.2% and the Si concentration exceeds 1.8%, a large amount of Ni ₂ Si, Ni ₅ Si ₂ or the like crystallizes or precipitates during casting, and during forging or heat treatment It becomes easy to break. In addition, if the Ni concentration exceeds 7.2%, the electrical conductivity also decreases, and the thermal conductivity decreases. In consideration of the balance between manufacturability and characteristics, the Ni concentration is desirably a lower limit of 3.5% and an upper limit of 6.6%. The Si concentration is desirably a lower limit of 0.8% and an upper limit of 1.7%. The Ni / Si ratio is preferably 3.8 to 4.6. If it deviates from this ratio, the excess Ni or Si is dissolved in the Cu matrix and the thermal conductivity is lowered.

Zr: 0.02 to 0.35%
Zr has a strong affinity with sulfur, so it forms a compound with sulfur and reduces the segregation of sulfides to the grain boundaries that are the cause of work cracking (hot work cracking). Improvement). On the other hand, as a result of intensive investigations by the inventors, it has been found that the diffusion of Ni and Si is suppressed by containing Zr, Ni ₂ Si precipitated at the grain boundary is reduced, and ductility after aging is improved. . To obtain this effect, 0.02% or more of Zr is contained. However, if the content exceeds 0.35%, the productivity and characteristics deteriorate due to the increase and aggregation of crystallized substances such as Zr oxide and Ni ₂ SiZr, so the upper limit is made 0.35%. Considering the balance between manufacturability and characteristics, the lower limit is preferably 0.05% and the upper limit is 0.3%.

P: 0.002 to 0.05%
P increases the strength by increasing the density of fine precipitates. Further, the hardness is increased by forming a compound containing a small amount of P in Ni, Si, Zr and Ni ₂ Si or Ni ₂ SiZr. In order to acquire these effects, it contains 0.002% or more. However, if it exceeds 0.05%, the thermal conductivity is greatly reduced, so the upper limit is made 0.05%. For the same reason, it is desirable to set the lower limit to 0.01% and the upper limit to 0.04%.

Cr, Mn, Zn: 1.5% or less in total Cr, Mn, Zn contains one or more as desired.
Cr forms an intermetallic compound with Si, and has the effect of improving the strength and miniaturizing the crystal grains. Mn has a strong affinity for sulfur, so it forms a compound with sulfur and reduces workability (hot workability) by reducing the segregation of sulfides to the grain boundaries that cause work cracking (hot work cracking). ). Zn improves the strength by solid solution strengthening. Moreover, if an inexpensive brass scrap can be used at the time of melt | dissolution, a manufacturing cost can be reduced. However, if Cr, Mn, and Zn are excessively contained in the total amount, the thermal conductivity is lowered. Therefore, the total amount of Cr, Mn, and Zn is set to 1.5% or less.
Desirably, the total amount is 1.0% or less. Moreover, when it contains 1 or more types of Cr, Mn, and Zn, it is desirable to set it as 0.1% or more in total amount.

  As described above, according to the present invention, it is possible to obtain a high-strength copper alloy forged material that is less susceptible to cracking during processing or heat treatment and that has characteristics of high hardness, high strength, and high thermal conductivity.

The high-strength copper alloy forged material of the present invention can be produced by a conventional method.
The copper alloy used in the present invention can be melted by a conventional method, and an ingot can be obtained by melting the material in a vacuum atmosphere, an inert atmosphere, an air atmosphere or the like. The atmosphere is preferably a vacuum atmosphere or an inert atmosphere. Further, secondary melting using an electroslag remelting furnace or the like may be performed. It is also possible to obtain a plate material by a continuous casting method.

  The copper alloy is processed as necessary. The content of the processing is not particularly limited as the present invention, and a known forging method such as pressing, hammering, rolling or the like can be employed, and the characteristics of the present invention can be obtained by using any processing method. Is possible. The processing is preferably hot processing in consideration of manufacturability, and further, hot processing performed at 600 ° C. or higher is preferable, but the same characteristics as hot processing can be obtained even at processing at room temperature. Further, the processing may be a combination of hot processing and cold processing. Further, forging and hot forging are desirable as processing, and it is more desirable to perform hot forging at 600 ° C. or higher.

The processed copper alloy material can be subjected to a solution treatment after processing or during processing. The conditions of the solid solution treatment are, for example, holding at 800 to 1000 ° C. for 1 to 10 hours, and then cooling a temperature range of 500 ° C. or higher at a cooling rate of 5 ° C./second or more in order to sufficiently dissolve Ni and Si. Is mentioned.
The processed copper alloy material can be subjected to aging treatment after the solution treatment or as processed. As for the conditions of an aging treatment, what hold | maintains at 400-500 degreeC for 1 to 30 hours is mentioned, for example.
The obtained high-strength copper alloy material has characteristics such that 0.2% proof stress is 650 MPa or more, elongation is 5% or more, and conductivity is 30% IACS or more.
In addition, although this invention has the characteristic outstanding as a forging material, in the composition of this invention, characteristics, such as favorable ductility, can be acquired even in the casting material which is not processed.

Examples of the present invention will be described below.
Raw materials were blended so as to have the component composition shown in Table 1 (including other inevitable impurities) and melted in a vacuum induction melting furnace to prepare an alloy having a diameter of 100 mm × 200 mm. This alloy was hot-forged with a hammer at 900 ° C. to obtain a 25 mm thick plate material, which was kept at 970 ° C. for 4 hours and then subjected to a solution treatment in which it was cooled with water. Then, the aging treatment suitable for the raw material of each component for 1 to 30 hours was performed at 400-500 degreeC, and the test material was obtained.

The following evaluation was performed on the prepared specimen (tensile test).
Each specimen was subjected to a normal temperature tensile test based on JISZ2201 and Z2241, and 0.2% proof stress (YS), tensile strength (TS), elongation, and drawing were evaluated. The measurement results are shown in Table 2.
(Vickers hardness)
For each specimen, the Vickers hardness was measured with a load of 5 kg based on JISZ2244. The measurement results are shown in Table 2.
(Thermal conductivity)
The conductivity was measured for each specimen. As shown in the Wiedemann-Franz rule, the thermal conductivity and the electrical conductivity are in a substantially proportional relationship, and the thermal conductivity can be evaluated by the electrical conductivity. The measurement results are shown in Table 2.

As shown in Table 2, the examples of the present invention had a 0.2% proof stress of 650 MPa or more, an elongation of 5% or more, and a conductivity of 30% IACS or more. Moreover, it had a hardness equal to or higher than that of the comparative example.
As described above, according to the present invention, by including appropriate amounts of Zr and P in the Ni—Si—Cu alloy, excellent performance is achieved in that strength, ductility, and altitude are increased while maintaining high conductivity, that is, high thermal conductivity. It was revealed that

Claims (2)

In mass%, Ni: 3 to 7.2%, Si: 0.7 to 1.8%, Zr: 0.02 to 0.35%, P: 0.002 to 0.05%, the balance There Ri Do Cu and inevitable impurities, 0.2% proof stress above 650 MPa, elongation of 5% or more, high strength copper alloy forging conductivity and characterized in that 30% IACS or more. In mass%, Ni: 3 to 7.2%, Si: 0.7 to 1.8%, Zr: 0.02 to 0.35%, P: 0.002 to 0.05%, , Cr, Mn, and containing less than 1.5% in total of one or more of Zn, the balance Ri Do Cu and inevitable impurities, 0.2% proof stress above 650 MPa, elongation of 5% or more, conductivity A high-strength copper alloy forging having a rate of 30% IACS or more .