EP4394064A1 - Lead-free free-cutting beryllium copper alloy - Google Patents

Lead-free free-cutting beryllium copper alloy Download PDF

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Publication number
EP4394064A1
EP4394064A1 EP23866641.6A EP23866641A EP4394064A1 EP 4394064 A1 EP4394064 A1 EP 4394064A1 EP 23866641 A EP23866641 A EP 23866641A EP 4394064 A1 EP4394064 A1 EP 4394064A1
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EP
European Patent Office
Prior art keywords
free
copper alloy
beryllium copper
lead
cutting
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Pending
Application number
EP23866641.6A
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German (de)
English (en)
French (fr)
Inventor
Hiromitsu Uchiyama
Koki Chiba
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NGK Insulators Ltd
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NGK Insulators Ltd
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Publication of EP4394064A1 publication Critical patent/EP4394064A1/en
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C9/00—Alloys based on copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C9/00—Alloys based on copper
    • C22C9/10—Alloys based on copper with silicon as the next major constituent
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/08—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of copper or alloys based thereon

Definitions

  • the present invention relates to a lead-free free-cutting beryllium copper alloy.
  • Patent Literature 1 JPS50-139017A discloses a quaternary copper alloy for spring materials, composed of from 0.5% to 1.5% of Be, from 0.2% to 3.0% of Sn, from 0.5% to 2.0% of Si, and the balance being Cu and inevitable impurities as an example of beryllium copper alloys.
  • a free-cutting beryllium copper alloy (UNS No.: C17300) is generally known as a beryllium copper alloy with superior machinability. This alloy is improved in machinability by allowing beryllium copper to contain from about 0.2% to 0.6% by weight of lead (Pb).
  • Patent Literature 2 JPS54-30369B discloses a free-cutting beryllium copper alloy as such a copper alloy, in which a copper alloy containing 0.5% to 4% by weight of Be is allowed to contain from 0.01% to 3% by weight of one selected from Pb, Te, and Bi, from 0.01% to 5% by weight of rare earth elements, and from 0.1% to 5% by weight of Al or Si.
  • Patent Literature 3 JP2000-119775A discloses a leadless free-cutting copper alloy defined by an alloy composition composed of from 69% to 79% by weight of Cu, from 2.0% to 4.0% by weight of Si, and the balance consisting of Zn.
  • Patent Literature 4 JP2021-42459A discloses a free-cutting copper alloy containing from 58.5 mass% to 63.5 mass% of Cu, from more than 0.4 mass% to 1.0 mass% of Si, from 0.003 mass% to 0.25 mass% of Pb, from 0.005 mass% to 0.19 mass% of P, and the balance composed of Zn and inevitable impurities.
  • Lead-containing copper alloys including free-cutting beryllium copper alloys as disclosed in Patent Literature 2 are superior in machinability, as described above, and accordingly have been conventionally used as a constituent material of various products.
  • lead is a harmful substance that adversely affects the human body and environment, and its use has tended to be greatly restricted in recent years.
  • lead-free free-cutting brass has been developed, as disclosed in Patent Literatures 3 and 4.
  • beryllium copper alloys however, there is no practical free-cutting material free from lead, and lead-free free-cutting beryllium copper alloys have been long awaited to be developed.
  • an object of the present invention is to provide a lead-free free-cutting beryllium copper alloy that is superior in machinability.
  • the present invention provides the following aspects:
  • the lead-free free-cutting beryllium copper alloy according to the present invention consists of from 1.80% to 2.10% by weight of Be, from 0.10% to 3.00% by weight of Si, from 0.20% to 0.40% by weight of Co, from 0% to 0.10% by weight of Fe, from 0% to 0.10% by weight of Ni, and the balance being Cu and inevitable impurities.
  • lead-free free-cutting beryllium copper alloy contains no lead (Pb).
  • This copper alloy has a matrix phase being an ⁇ phase, a Si-rich phase being a ⁇ phase rich in Si, and Co-Be-Si intermetallic compound grains.
  • the Co-Be-Si intermetallic compound grains contain Co, Be, and Si, and optionally Fe and/or Ni.
  • a specific microstructure formed by allowing a beryllium copper alloy containing from 1.80% to 2.10% by weight of Be to contain from 0.10% to 3.00% by weight of Si can provide a lead-free beryllium copper alloy exhibiting superior machinability.
  • Lead-containing copper alloys including free-cutting beryllium copper alloys, are superior in machinability, as described above, and accordingly have been conventionally used as a constituent material of various products.
  • lead is a harmful substance that adversely affects the human body and environment, and its use has tended to be greatly restricted in recent years.
  • the lead-free free-cutting beryllium copper alloy of the present invention can solve the above issue favorably. More specifically, allowing a beryllium copper alloy to contain Si reduces the cutting resistance of the beryllium copper alloy.
  • the swarf produced by cutting beryllium copper alloys containing Si is easy to shear into chips and unlikely to wind around the tool.
  • the beryllium copper alloy of the present invention exhibits superior machinability not only in terms of reducing cutting resistance but also in terms of improving the shapes of the swarf.
  • "lead-free" in the lead-free free-cutting beryllium copper alloy means that the lead content is lower than or equal to the detection limit in the elemental analysis of the copper alloy.
  • Si-rich phases and Co-Be-Si intermetallic compound grains containing Si probably serve as a stress concentration origin of shear failure to facilitate the braking of the swarf into smaller pieces.
  • Be imparts superior fundamental performance (strength, workability, fatigue properties, heat resistance, corrosion resistance, etc.) as beryllium copper alloy to copper alloy.
  • the Be content of the copper alloy of the present invention is from 1.80% to 2.10% by weight and is preferably from 1.80% to 2.00% by weight. A Be content in such a range can lead to the above-mentioned fundamental performance effectively and prevent excess Be from reducing electric conductivity.
  • Si forms Si-rich phases and Co-Be-Si intermetallic compound grains to impart superior machinability to beryllium copper alloy.
  • the Si content of the copper alloy of the present invention is from 0.10% to 3.00% by weight, preferably from 0.30% to 2.50% by weight, more preferably from 0.45% to 2.50% by weight, still more preferably from 0.50% to 2.20% by weight, particularly preferably from 0.80% to 2.00% by weight and is, for example, from 1.00% to 2.00% by weight.
  • a Si content in such a range can improve machinability effectively and prevent excess Si from reducing productivity (causing cracking during forging) in actual operations.
  • the Si content of the copper alloy can be preferably from 0.45% to 3.00% by weight, more preferably from 0.50% to 3.00% by weight, particularly preferably from 1.00% to 3.00% by weight, for example, from 2.00% to 3.00% by weight.
  • Co forms Co-Be-Si intermetallic compound grains to impart superior machinability to beryllium copper alloy.
  • the Co content of the copper alloy of the present invention is from 0.20% to 0.40% by weight, preferably from 0.20% to 0.35% by weight, more preferably from 0.22% to 0.30% by weight, and particularly preferably from 0.22% to 0.28% by weight.
  • a Co content in such a range enables effective crystal refinement and the improvement of copper alloy properties and can prevent excess Co from reducing productivity in actual operations.
  • Fe and Ni are optional elements that may be considered as impurities in the copper alloy of the present invention, and desired to be as little as possible because high Fe and Ni contents degrade mechanical properties. Accordingly, the Fe and Ni contents of the copper alloy of the present invention are each from 0% to 0.10% by weight, preferably from 0% to 0.005% by weight.
  • the copper alloy of the present invention has a microstructure including a matrix phase, Si-rich phases, and Co-Be-Si intermetallic compound grains.
  • the Si-rich phases are present in the matrix phase
  • the Co-Be-Si intermetallic compound grains are present at the interfaces between the Si-rich phases and the matrix phase.
  • the matrix phase is defined by an ⁇ phase and contributes to the superior fundamental performance (strength, workability, fatigue properties, heat resistance, corrosion resistance, etc.) as beryllium copper alloy.
  • a Si-rich phase is defined by a ⁇ phase rich in Si and contributes to improving the machinability.
  • the presence of Si in the matrix phase improves shearability and facilitates breaking the swarf into smaller pieces.
  • the expression "rich in Si” means that Si is detected in a higher concentration in the elemental analysis than in the matrix phase ( ⁇ phase) and not necessarily in a higher concentration than in Co-Be-Si intermetallic compound grains.
  • the matrix phase has a face-centered cubic (FCC) lattice crystal structure
  • the Si-rich phase has a body-centered cubic (BCC) lattice crystal structure.
  • the BCC structure is unlikely to deform and more shearable than the FCC structure. This means that Si-rich phases having a BCC structure can also contribute to improving the machinability.
  • the percentage of area S BCC of BCC regions identified as body-centered cubic (BCC) lattices relative to the sum of area S FCC of FCC regions identified as face-centered cubic (FCC) lattices and area S BCC of BCC regions is preferably 5% or more, more preferably from 5 to 40%, still more preferably from 10 to 30%, particularly preferably from 15 to 30%, and most preferably from 15 to 25%.
  • the EBSD measurement can be conducted according to the procedure and conditions described in the Examples below.
  • Co-Be-Si intermetallic compound grains also contribute to improving the machinability.
  • the Co-Be-Si intermetallic compound grains contain Co, Be, and Si, and optionally Fe and/or Ni.
  • Co-Be-Si intermetallic compound grains contain Co, Be, and Si as essential elements, and these elements are dominant.
  • Fe and Ni are optional elements or trace elements that can be considered impurities, as mentioned above and are, therefore, not considered dominant in the Co-Be-Si intermetallic compound grains.
  • the Co-Be-Si intermetallic compound grains preferably have a hardness from 1.0 to 12.0 GPa, more preferably from 1.5 to 7.5 GPa, and still more preferably from 2.0 to 6.0 GPa as measured by a nanoindentation test in accordance with ISO14577. Having a hardness in such a range achieves machinability effectively.
  • the nanoindentation test measures hardness in a small region at many points, and the resulting hardnesses have a wide distribution. Therefore, 100% of the measured points of the Co-Be-Si intermetallic compound grains need not be within the above ranges as long as the majority (for example, 90% or more) is within the above ranges. Hence, it is acceptable that the distribution of measured hardnesses includes hardnesses less than 1.0 GPa or higher than 12.0 GPa to a small extent (for example, less than 10%).
  • the number of Co-Be-Si intermetallic compound grains is not limited, provided that the machinability of the beryllium copper alloy can be improved without impairing the above-described fundamental performance. From the viewpoint of improving machinability more effectively, the number of Co-Be-Si intermetallic compound grains at a cross section of the copper alloy is preferably 320 or less per unit area of 1 mm 2 , more preferably from 50 to 300, and still more preferably from 80 to 200.
  • the shape of Co-Be-Si intermetallic compound grains is not limited to spherical and may be plate-like, rod-shaped, needle-shaped, or in variant shapes without limitation. Accordingly, the size of the Co-Be-Si intermetallic compound grains is preferably specified by cross-sectional area rather than by diameter.
  • the Co-Be-Si intermetallic compound grains have a cross-sectional area preferably from 0.3 to 70 ⁇ m 2 per grain, more preferably from 1.0 to 65 ⁇ m 2 , and still more preferably from 5.0 to 60 ⁇ m 2 .
  • the copper alloy of the present invention has superior machinability, as described above, and when a cross section of the swarf generated by cutting the copper alloy is observed along a longitudinal direction, the cross section of the swarf has a sheared profile with zigzag-shaped unevenness.
  • the zigzag-shaped unevenness preferably satisfies the relationship 1.10 ⁇ h 2 /h 1 ⁇ 6.60, more preferably 2.0 ⁇ h 2 /h 1 ⁇ 6.6, and still more preferably 2.5 ⁇ h 2 /h 1 ⁇ 6.6, wherein as depicted in Figures 8 , h 1 represents the average of distances between recesses in the zigzag-shaped unevenness, and h 2 represents the average of heights of the protrusions in the unevenness.
  • h 1 represents the average of distances between recesses in the zigzag-shaped unevenness
  • h 2 represents the average of heights of the protrusions in the unevenness.
  • the lead-free free-cutting beryllium copper alloy of the present invention can be preferably produced by, but not limited to, (a) melting and casting of raw materials for the above-described composition; (b) homogenization heat treatment; (c) hot working; (d) cold working; (e) solution annealing; and (f) aging treatment, in this order.
  • the preferred aspects of copper alloys have been described above, and thus descriptions will be omitted here.
  • one or more raw materials whose constituents are adjusted to result in the above-described composition are melted into a copper alloy molten metal. If a given element is added, the element alone, a master alloy, or the like can be added to the raw material. Alternatively, a raw material containing such additive elements may be melted together with a copper raw material.
  • a copper alloy raw material that can provide the compositions presented in Table 1 was prepared.
  • the copper alloy raw material was melted, and the resulting molten metal was poured into a mold to form a cylindrical ingot (billet).
  • the resulting beryllium copper alloy sample (hereinafter referred to as a copper alloy sample) was evaluated in terms of the following.
  • the hardness (GPa) of Co-Be-Si intermetallic compound grains at the cross section of beryllium copper alloys was measured at each microregion by a nanoindentation test. This test was performed in accordance with ISO14577 on samples with a Poisson's ratio of 0.3 under the conditions of 0.25 mN maximum load, 60 ⁇ m (X axis) ⁇ 60 ⁇ m (Y axis) measurement region, and 60 (X axis) ⁇ 60 (Y axis) measurement points using a nanoindenter (trade name: iMicro nanoindenter, manufactured by KLA Corporation). The hardness distribution of the Co-Be-Si intermetallic compound grains thus measured were represented by histograms.
  • Copper alloy samples were used as work materials, and the cutting resistance (N) of the work materials when cut with a tool (tool bit) was examined. More specifically, a work material 2 was lowered while being rotated to be spirally cut with a tool 4, as depicted in Figure 10 under the test environment and cutting conditions below. At this time, the cutting resistance of the work material was measured with a multi-component force dynamometer (9129AA, manufactured by Kistler Group). The results are presented in Table 1.

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EP23866641.6A 2022-10-28 2023-09-01 Lead-free free-cutting beryllium copper alloy Pending EP4394064A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2022173377 2022-10-28
PCT/JP2023/032138 WO2024090037A1 (ja) 2022-10-28 2023-09-01 鉛フリー快削ベリリウム銅合金

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EP4394064A1 true EP4394064A1 (en) 2024-07-03

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US (1) US20240263277A1 (enrdf_load_stackoverflow)
EP (1) EP4394064A1 (enrdf_load_stackoverflow)
JP (1) JPWO2024090037A1 (enrdf_load_stackoverflow)
KR (1) KR20240063124A (enrdf_load_stackoverflow)
CN (1) CN118265806A (enrdf_load_stackoverflow)
TW (1) TWI866458B (enrdf_load_stackoverflow)
WO (1) WO2024090037A1 (enrdf_load_stackoverflow)

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CN118910463A (zh) * 2024-10-10 2024-11-08 国工恒昌新材料(义乌)有限公司 一种vcm弹片用高导电率铍铜箔材及其制备方法

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JPS63125648A (ja) * 1986-11-13 1988-05-28 Ngk Insulators Ltd ベリリウム銅合金の製造法
JPS63143247A (ja) * 1986-12-06 1988-06-15 Ngk Insulators Ltd 鋳造方法
JP3378430B2 (ja) * 1996-03-28 2003-02-17 日本碍子株式会社 耐熱性および曲げ部の美観に優れる高強度ベリリウム銅合金
JP3734372B2 (ja) 1998-10-12 2006-01-11 三宝伸銅工業株式会社 無鉛快削性銅合金
JP5135496B2 (ja) * 2007-06-01 2013-02-06 Ｄｏｗａメタルテック株式会社 Ｃｕ−Ｂｅ系銅合金板材およびその製造法
KR102623143B1 (ko) 2019-06-25 2024-01-09 미쓰비시 마테리알 가부시키가이샤 쾌삭성 구리 합금 주물, 및 쾌삭성 구리 합금 주물의 제조 방법
CN111057886B (zh) * 2019-10-29 2021-06-22 宁夏中色新材料有限公司 一种铍铜铸轧辊套的制备方法和铍铜铸轧辊套
JP2021155837A (ja) * 2020-03-30 2021-10-07 日本碍子株式会社 ベリリウム銅合金リング及びその製造方法
CN113174509B (zh) * 2021-03-15 2022-10-14 江阴金湾合金材料有限公司 一种高强度铍铜合金棒及其制备工艺

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US20240263277A1 (en) 2024-08-08
CN118265806A (zh) 2024-06-28
WO2024090037A1 (ja) 2024-05-02
TWI866458B (zh) 2024-12-11
JPWO2024090037A1 (enrdf_load_stackoverflow) 2024-05-02
KR20240063124A (ko) 2024-05-09
TW202428897A (zh) 2024-07-16

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