U.S. patent application number 13/646259 was filed with the patent office on 2013-01-31 for copper alloy wrought material, copper alloy part, and method of producing a copper alloy wrought material.
This patent application is currently assigned to FURUKAWA ELECTRIC CO., LTD.. The applicant listed for this patent is FURUKAWA ELECTRIC CO., LTD.. Invention is credited to Chizuna KAMATA, Hideo KANEKO, Kazuhiro KOSEKI, Kazuo KURAHASHI, Kensaku ODA, Isao TAKAHASHI, Yoshihiro YAMAMOTO.
Application Number | 20130028784 13/646259 |
Document ID | / |
Family ID | 44762237 |
Filed Date | 2013-01-31 |
United States Patent
Application |
20130028784 |
Kind Code |
A1 |
TAKAHASHI; Isao ; et
al. |
January 31, 2013 |
COPPER ALLOY WROUGHT MATERIAL, COPPER ALLOY PART, AND METHOD OF
PRODUCING A COPPER ALLOY WROUGHT MATERIAL
Abstract
A copper alloy wrought material, containing 1.5 to 7.0 mass % of
Ni, 0.3 to 2.3 mass % of Si, 0.02 to 1.0 mass % of S, and
optionally at least one selected from the group consisting of Sn,
Mn, Co, Zr, Ti, Fe, Cr, Al, P, and Zn in a total amount of 0.05 to
2.0 mass %, with the balance being Cu and unavoidable impurities,
wherein sulfide particles, which contribute to machinability, are
dispersed therein, in which an average diameter of the sulfide
particles is 0.1 to 10 .mu.m, and in which an area ratio of the
sulfide particles is 0.1 to 10%, and wherein the copper alloy
wrought material has a tensile strength of 500 MPa or greater and
an electrical conductivity of 25% IACS or higher.
Inventors: |
TAKAHASHI; Isao; (Tokyo,
JP) ; KANEKO; Hideo; (Tokyo, JP) ; KAMATA;
Chizuna; (Tokyo, JP) ; YAMAMOTO; Yoshihiro;
(Tokyo, JP) ; ODA; Kensaku; (Tokyo, JP) ;
KURAHASHI; Kazuo; (Tokyo, JP) ; KOSEKI; Kazuhiro;
(Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FURUKAWA ELECTRIC CO., LTD.; |
Tokyo |
|
JP |
|
|
Assignee: |
FURUKAWA ELECTRIC CO., LTD.
Tokyo
JP
|
Family ID: |
44762237 |
Appl. No.: |
13/646259 |
Filed: |
October 5, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2010/073451 |
Dec 24, 2010 |
|
|
|
13646259 |
|
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Current U.S.
Class: |
420/471 ;
148/684; 164/122; 420/473; 420/479; 420/481; 420/482; 420/485;
420/488 |
Current CPC
Class: |
C22C 1/10 20130101; C22F
1/08 20130101; C22C 9/10 20130101; C22C 9/06 20130101; C22F 1/00
20130101 |
Class at
Publication: |
420/471 ;
420/473; 420/479; 420/481; 420/482; 420/488; 420/485; 164/122;
148/684 |
International
Class: |
C22C 9/06 20060101
C22C009/06; C22F 1/08 20060101 C22F001/08; B22D 27/04 20060101
B22D027/04 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 7, 2010 |
JP |
2010-088228 |
Jun 24, 2010 |
JP |
2010-143420 |
Sep 17, 2010 |
JP |
2010-210201 |
Dec 16, 2010 |
JP |
2010-280946 |
Claims
1. A copper alloy wrought material, containing 1.5 to 7.0 mass % of
Ni, 0.3 to 2.3 mass % of Si, 0.02 to 1.0 mass % of S, and
optionally at least one selected from the group consisting of Sn,
Mn, Co, Zr, Ti, Fe, Cr, Al, P, and Zn in a total amount of 0.05 to
2.0 mass %, with the balance being Cu and unavoidable impurities,
wherein sulfide particles are dispersed therein, in which an
average diameter of the sulfide particles is 0.1 to 10 .mu.m, and
in which an area ratio of the sulfide particles is 0.1 to 10%, and
wherein the copper alloy wrought material has a tensile strength of
500 MPa or greater and an electrical conductivity of 25% IACS or
higher.
2. The copper alloy wrought material according to claim 1, wherein
the sulfide particles are composed of at least one selected from
the group consisting of Cu--S, Mn--S, Zr--S, Ti--S, Fe--S, Al--S,
Cr--S, and Zn--S.
3. A copper alloy part, formed by subjecting the copper alloy
wrought material according to claim 1 to cutting.
4. A method of producing the copper alloy wrought material
according to claim 1, wherein a cooling speed at the time of
casting is set to 0.1 to 50.degree. C./second.
5. A copper alloy wrought material, containing 1.5 to 7.0 mass % of
Ni, 0.3 to 2.3 mass % of Si, 0.02 to 1.0 mass % of S, and
optionally at least one selected from the group consisting of Sn,
Mn, Co, Zr, Ti, Fe, Cr, Al, P, and Zn in a total amount of 0.05 to
2.0 mass %, with the balance being Cu and unavoidable impurities,
wherein sulfide particles are present in crystals of the matrix at
40% or larger in an area ratio of the sulfide particles in a
cross-section parallel to the wrought direction, wherein the
sulfide particles having an aspect ratio in the cross-section
parallel to the wrought direction of 1:1 to 1:100 are dispersed in
the matrix, and wherein the copper alloy wrought material has a
tensile strength of 500 MPa or greater and an electrical
conductivity of 25% IACS or higher.
6. The copper alloy wrought material according to claim 5, wherein
the sulfide particles are composed of at least one selected from
sulfides of Cu--S, Mn--S, Zr--S, Ti--S, Fe--S, Al--S, Cr--S, and
Zn--S.
7. A copper alloy part, formed by subjecting the copper alloy
wrought material according to claim 5 to cutting.
8. A method of producing the copper alloy wrought material
according to claim 5, containing the steps of: conducting any one
of steps (a) and (b), at the time of working a copper alloy
composition containing 1.5 to 7.0 mass % of Ni, 0.3 to 2.3 mass %
of Si, 0.02 to 1.0 mass % of S, and optionally at least one
selected from the group consisting of Sn, Mn, Co, Zr, Ti, Fe, Cr,
Al, P, and Zn in a total amount of 0.05 to 2.0 mass %, with the
balance being Cu and unavoidable impurities; area-reduction working
at 0% to 95%; and subjecting the resultant worked-product to aging
at 350 to 600.degree. C.: (a) subjecting the copper alloy
composition to hot working, and then to quenching; (b) subjecting
the copper alloy composition to hot working, then to cold working
and a heat treatment at a temperature of 600.degree. C. to
1,000.degree. C. repeatedly for one or more times, and to a
solution treatment before final cold-working.
Description
TECHNICAL FIELD
[0001] The present invention relates to a metal part that can be
used in electronic equipments, precision machines, automobiles, and
the like, specifically to a copper alloy part produced by cutting.
Further, the present invention relates to a copper alloy wrought
material suitable for that copper alloy part, and to a method of
producing the same.
BACKGROUND ART
[0002] Examples of a method of producing a metal part include
cutting, such as turning and punching. Cutting is a working method
particularly effective for the production of a part which has a
complicated shape or a part which requires a high dimensional
accuracy. In the case of performing cutting, machinability often
becomes a problem. Machinability is represented by items, such as
cut chip treatment, tool service life, cutting resistance, and cut
face roughness, and efforts have been made to improve the material
in order to enhance those. Copper alloys are used in many metal
parts for the reasons, such as high in mechanical strength,
excellent in electrical conductivity and heat conductivity,
excellent in corrosion resistance, and excellent in color tone.
Copper alloys are also frequently subjected to working by cutting,
and are used in applications, such as, for example, faucets for tap
water, valves, gears, and ornaments. In these applications, use is
made of alloys prepared by adding lead to brass (Cu--Zn-based),
bronze (Cu--Sn-based), aluminum-bronze (Cu--Al-based), and nickel
silver (Cu--Zn--Ni-based), so as to enhance machinability. However,
those applications are ones which do not require high mechanical
strength or high electrical conductivity.
[0003] In the applications which require high mechanical strength
or high electrical conductivity, for example, in an application,
such as a pin material for coaxial connectors, use is made of any
of free-cutting phosphor bronze (see Patent Literature 1) and
free-cutting beryllium copper (see Patent Literature 2), which are
obtained by adding lead to phosphor bronze and beryllium copper,
respectively. These materials are subjected to cutting with a
precision machine tool such, as an NC lathe, and are used in
high-reliability parts for the applications of electronic
equipments or the like.
[0004] As such, in order to enhance the machinability of copper
alloys, generally lead is added. This is because, since lead does
not form any solid solution in a copper alloy, lead is finely
dispersed in the material, and cut chips are apt to be broken and
separated off at the region in the cutting. However, since lead is
considered to have adverse affection on the human body and the
environment, use of lead has become restricted, and thus there is
an increasing demand for a material which does not contain lead and
has improved machinability. As an alternative material for copper
alloys containing lead, there are known copper alloys obtained by
adding bismuth to brass or bronze (see Patent Literatures 3 and 4).
Further, it is also known that, in brass, the zinc concentration is
increased to form a .beta. phase or a .gamma. phase, which are each
a copper-zinc-based compound, or alternatively silicon is added to
form a .kappa. phase, which is a copper-silicon-based compound, so
that any of these compounds is made to serve as the starting point
for the breakage and separation off of cut chips, and thereby
machinability is enhanced (Patent Literatures 5 and 6). Further,
there is a known method of adding sulfur to bronze to form a
sulfide, and thereby making the sulfide to act as the starting
point for the breakage and separation off of cut chips (Patent
Literature 7). In addition to that, in connection with making the
sulfide as the starting point for the breakage and separation off
of cut chips, there is also a known method related to
age-precipitation-type alloys of a copper-zirconium-based and a
copper-titanium-based (Patent Literature 8).
CITATION LIST
Patent Literatures
[0005] Patent Literature 1: JP-A-50-066423 ("JP-A" means unexamined
published Japanese patent application)
[0006] Patent Literature 2: JP-A-52-117244
[0007] Patent Literature 3: JP-A-2001-059123
[0008] Patent Literature 4: JP-A-2000-336442
[0009] Patent Literature 5: JP-A-2000-319737
[0010] Patent Literature 6: JP-A-2004-183056
[0011] Patent Literature 7: JP-A-2006-152373
[0012] Patent Literature 8: JP-A-2001-240923
[0013] Patent Literature 9: JP-A-2008-75172
[0014] Patent Literature 10: JP-A-6-212374
[0015] Patent Literature 11: JP-A-7-90520
DISCLOSURE OF INVENTION
Technical Problem
[0016] However, the techniques descried in the patent literatures
have the following problems.
[0017] In the techniques described in Patent Literatures 1 and 2,
lead is used as an additive element for enhancing machinability as
described above, and there is a concern for a load to the
environment. Particularly, in the technique described in Patent
Literature 2, there is no substance which can replace lead as an
additive element for enhancing the machinability of free-cutting
beryllium copper, and beryllium itself is also considered as one of
elements having adverse affection on the environment. Therefore,
there is an increasing demand for not only an alternative material
of copper alloys to which lead is added, but also an alternative
material of beryllium copper.
[0018] Further, in the techniques described in Patent Literatures 3
and 4, when bismuth is added, machinability is improved; however,
the alloy becomes to be apt to be broken in working, and
particularly, it becomes difficult to perform hot working. That is,
another means is necessary to improve hot workability. The
compounds formed in the alloys described in Patent Literatures 5
and 6 are unique to a brass-system, and it is substantially
difficult to apply the compounds to other alloy systems. Patent
Literature 7 is a technique related to a casting, and the technique
is preferable in the case of directly cutting a casting; however,
there is no disclosure on a technique for obtaining a wrought
material (plastically-worked material), such as a bar material or a
sheet material. The material obtained by the technique described in
Patent Literature 8 is generally low in mechanical strength, and
for example, the material is insufficient for applications which
require high mechanical strength, such as a pin material for
coaxial connectors. Thus, there is a need to apply other
techniques.
[0019] The materials disclosed in Patent Literatures 1 to 8 are not
Corson alloys (Cu--Ni--Si-based copper alloys), and actually do not
serve as materials to which reference can be made. JP-A-2008-75172
(Patent Literature 9) discloses a Cu--Ni--Si-based alloy provided
for use as an electronic material, which has improved electrical
conductivity, mechanical strength, bending property, and stress
relaxation resistance in combination, with minimized addition of
other alloying elements. However, there is no disclosure on the
balance between ductility and malleability (drawability) and
machinability standing together, and there is no mention on the
adjustment of the sulfur concentration. JP-A-6-212374 (Patent
Literature 10) and JP-A-7-90520 (Patent Literature 11) disclose
Corson alloys with ductility and malleability taken into
consideration, but in both of the alloys, the sulfur concentration
is restricted to 20 ppm (0.002%) or less because of the ductility
and malleability.
[0020] The present invention has been made in view of such
problems, and is contemplated for providing a copper alloy wrought
material which is excellent in machinability and ductility and
malleability, and which is optimal in applications in which high
mechanical strength or high electrical conductivity is required,
while attaining a reduced load to the environment. Further, the
present invention is contemplated for providing a copper alloy
part, which is obtained by subjecting the above-mentioned copper
alloy wrought material to cutting, and for providing a method of
producing the wrought material.
Solution to Problem
[0021] The inventors of the present invention, having been studied
keenly, found that, by controlling the size (average diameter) and
the area ratio of sulfide particles in an age-precipitation-type
copper alloy of a specific composition, a copper alloy wrought
material can be obtained, which is excellent in ductility and
malleability (drawability) (hot- and cold-workability) and
machinability, and which is also excellent in mechanical strength
and electrically conductivity. Further, the inventors found a
composition and a casting method, each of which is to obtain the
sulfide particles, and also found a composition, a microstructure,
and a casting method, each of which exhibits excellent hot
workability and cold workability.
[0022] Further, the inventors of the present invention, having been
studied keenly, found that, by forming sulfide particles in the
matrix of an age-precipitation-type copper alloy of a specific
composition, and by making 40% or more of the sulfide particles
exist in the grains of the matrix having a cross-section that is in
parallel to the wrought direction, and by making the sulfide
particles having an aspect ratio in the cross-section parallel to
the wrought direction of 1:1 to 1:100 be dispersed in the matrix, a
copper alloy wrought material can be obtained, which is excellent
in ductility and malleability (drawability) (hot- and
cold-workability) and machinability, and which is also excellent in
mechanical strength and electrically conductivity. Further, the
inventors found a composition and a production method, each of
which is to obtain the sulfide particles, and also found a
composition, a microstructure, and a production method, each of
which exhibits excellent hot workability and cold workability.
[0023] The present invention is attained based on those
findings.
[0024] That is, the present invention is to provide the following
means:
(1) A copper alloy wrought material, containing 1.5 to 7.0 mass %
of Ni, 0.3 to 2.3 mass % of Si, and 0.02 to 1.0 mass % of S, with
the balance being Cu and unavoidable impurities, wherein sulfide
particles are dispersed therein, in which a size (average diameter)
of the sulfide particles is 0.1 to 10 .mu.m, and in which an area
ratio of the sulfide particles is 0.1 to 10%, and wherein the
copper alloy wrought material has a tensile strength of 500 MPa or
greater and an electrical conductivity of 25% IACS or higher. (2)
The copper alloy wrought material as described in (1), further
containing at least one selected from the group consisting of Sn,
Mn, Co, Zr, Ti, Fe, Cr, Al, P, and Zn in a total amount of 0.05 to
2.0 mass %. (3) The copper alloy wrought material as described in
(1) or (2), wherein the sulfide particles are composed of at least
one selected from the group consisting of Cu--S, Mn--S, Zr--S,
Ti--S, Fe--S, Al--S, Cr--S, and Zn--S. (4) A copper alloy part,
formed by subjecting the copper alloy wrought material as described
in any one of (1) to (3) to cutting. (5) The copper alloy part as
described in (4), which is used in an electronic equipment part, a
structural part, or an element part. (6) A method of producing the
copper alloy wrought material as described in any one of (1) to
(3), wherein a cooling speed at the time of casting is set to 0.1
to 50.degree. C./second. (7) A copper alloy wrought material,
containing 1.5 to 7.0 mass % of Ni, 0.3 to 2.3 mass % of Si, and
0.02 to 1.0 mass % of S, with the balance being Cu and unavoidable
impurities, wherein sulfide particles are present in crystals of
the matrix at 40% or larger in an area ratio of the sulfide
particles in a cross-section parallel to the wrought direction,
wherein the sulfide particles having an aspect ratio in the
cross-section parallel to the wrought direction of 1:1 to 1:100 are
dispersed in the matrix, and wherein the copper alloy wrought
material has a tensile strength of 500 MPa or greater and an
electrical conductivity of 25% IACS or higher. (8) The copper alloy
wrought material as described in (7), further containing at least
one selected from the group consisting of Sn, Mn, Co, Zr, Ti, Fe,
Cr, Al, P, and Zn in a total amount of 0.05 to 2.0 mass %. (9) The
copper alloy wrought material as described in (7) or (8), wherein
the sulfide particles are composed of at least one selected from
sulfides of Cu--S, Mn--S, Zr--S, Ti--S, Fe--S, Al--S, Cr--S, and
Zn--S. (10) A copper alloy part, formed by subjecting the copper
alloy wrought material as described in any one of (7) to (9) to
cutting. (11) The copper alloy part as described in (10), which is
used in applications which require mechanical strength,
electrically conductivity, heat conductivity, and wear resistance,
such as an electronic equipment part, a structural part, and an
element part. (12) A method of producing the copper alloy wrought
material as described in any one of (7) to (9), containing the
steps of:
[0025] conducting any one of steps (a) and (b), at the time of
working a copper alloy composition containing 1.5 to 7.0 mass % of
Ni, 0.3 to 2.3 mass % of Si, and 0.02 to 1.0 mass % of S, with the
balance being Cu and unavoidable impurities;
[0026] area-reduction working at 0% to 95%; and
[0027] subjecting the resultant worked-product to aging, in which
the sulfide particles are present in crystals of the matrix at 40%
or larger in a total area of the sulfide particles dispersed in the
matrix in a cross-section parallel to the wrought direction, and in
which the sulfide particles having an aspect ratio in the
cross-section parallel to the wrought direction of 1:1 to 1:100 are
dispersed in the matrix:
[0028] (a) subjecting the copper alloy composition to hot working,
and then to quenching;
[0029] (b) subjecting the copper alloy composition to hot working,
then to cold working and a heat treatment at a temperature of
600.degree. C. to 1,000.degree. C. repeatedly for one or more
times, and to a solution treatment before final cold-working.
(13) The method of producing the copper alloy wrought material as
described in (12), wherein the copper alloy wrought material
further contains at least one selected from the group consisting of
Sn, Mn, Co, Zr, Ti, Fe, Cr, AI, P, and Zn in a total amount of 0.05
to 2.0 mass %.
[0030] Herein, the phrase that "sulfide particles are present in
crystals of the matrix at 40% or larger in an area ratio of the
sulfide particles in a cross-section that is in parallel to the
wrought direction" means that 40% or more of the sulfide particles
dispersed in the matrix are present in grain boundaries. Further,
the phrase that "sulfide particles having an aspect ratio in the
cross-section that is in parallel to the wrought direction of 1:1
to 1:100 are dispersed (in the matrix)" means that the aspect ratio
of all the sulfide particles dispersed in the matrix is within the
range of 1:1 to 1:100. Herein, the matrix refers to individual
regions, or a collection of the regions, surrounded by the grain
boundaries in an alloy structure, and typically, the matrix exists
in the form of islands each having an arbitrary shape, which are
respectively surrounded by the grain boundaries and are adjacent to
each other.
Advantageous Effects of Invention
[0031] The copper alloy wrought material of the present invention
is excellent in mechanical strength and electrically conductivity,
and is also excellent in machinability and ductility and
malleability (drawability), without utilizing an environmentally
hazardous substance, such as lead or beryllium. For example, in
order to prevent a decrease in the insertion and extraction force
that is required in connector pin materials, the decrease in the
insertion and extraction force can be suppressed by having a high
tensile strength in the same level of that of beryllium copper. The
present invention can suppress a decrease in the insertion and
extraction force in the same level of that of beryllium copper at a
tensile strength of 500 MPa or greater. Further, in a part of an
electronic equipment or the like, in which tensile strength or/and
electrically conductivity is desired, since the copper alloy
wrought material of the present invention has an electrical
conductivity of 25% IACS or higher, the alloy material is superior
to beryllium copper due to its excellent electrically conductivity.
Further, the copper alloy wrought material of the present invention
is preferably suitable as a material for a part of electronic
equipments or the like, which is produced by cutting. The copper
alloy part of the present invention can be produced with high
accuracy through cutting, and has sufficient characteristics that
are necessary as a part of electronic equipments and the like.
[0032] Other and further features and advantages of the invention
will appear more fully from the following description,
appropriately referring to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
{FIG. 1}
[0033] FIG. 1 is a diagram schematically showing a lateral side (a)
and the cross-section (b) of a copper alloy bar viewed in parallel
with the wrought direction.
{FIG. 2}
[0034] FIG. 2 is a diagram schematically showing the
cross-sectional structure of a copper alloy bar viewed under an
electron microscope (SEM) in parallel to the wrought direction, and
the diagram is an overview image of the grain boundaries and
sulfide particles.
{FIG. 3}
[0035] FIG. 3 is a diagram schematically showing the
cross-sectional structure of the copper alloy bar viewed under an
electron microscope (SEM) in parallel to the wrought direction, and
the diagram shows FIG. 2, with the sulfide particles on the grain
boundaries being excluded.
{FIG. 4}
[0036] FIG. 4 is a diagram explaining the aspect ratio of the
sulfide particles, shown as a magnification of a part of FIG.
2.
{FIG. 5}
[0037] FIG. 5 is a lateral side view schematically showing one
shape of the connector pins produced in Examples 1-3 and 2-3.
{FIG. 6}
[0038] FIG. 6 is a lateral side view schematically showing the
other shape of the connector pins produced in Examples 1-3 and
2-3.
MODE FOR CARRYING OUT THE INVENTION
[0039] Preferred embodiments of the copper alloy wrought material
of the present invention will be roughly divided into a first
embodiment and a second embodiment, and each described in detail.
Herein, with respect to the second embodiment, descriptions that
are common with the first embodiment may be omitted. These two
embodiments are intended to have special technical features that
are the same as or corresponding to each other, and to form a
single inventive concept. In the present specification, the term
"copper alloy" means that the material does not encompass the
conception of shape, and the terms "copper alloy material" and
"copper alloy wrought material" mean that the material encompasses
the conception of shape.
First Embodiment
<Ni and Si>
[0040] In a preferred embodiment of the copper alloy wrought
material of this embodiment, nickel (Ni) and silicon (Si) are added
to form a Ni--Si precipitate (Ni.sub.2Si) in the metal matrix by
controlling the content ratio of Ni and Si, to thereby achieve
precipitation hardening, and to enhance the mechanical strength and
electrically conductivity of the copper alloy wrought material.
This Ni--Si precipitate (Ni.sub.2Si: precipitate for precipitation
hardening) does not contribute much to enhancement of
machinability.
[0041] In a preferred embodiment of the copper alloy wrought
material of this embodiment, addition of sulfur (S) leads to the
formation of sulfide particles, in the matrix, which contribute to
enhancement of machinability. As the sulfide particles serve as the
starting points for the breakage and separation off of chips when
cutting is carried out, the chips become to be apt to be finely
broken and separated off, to enhance machinability. Further, by
controlling the cooling speed at the time of casting, the size
(average diameter) and the area ratio of the sulfide particles are
controlled, and chip breakability and separability is enhanced, but
hot workability and cold workability are not impaired. Thus,
wrought working such as extrusion, rolling or drawing, is made
possible.
[0042] The copper alloy in this embodiment is subjected to hot
working or cold working while being in the state in which nickel
(Ni) and silicon (Si) have formed a solid solution, or in the state
in which a Ni-Si precipitate has been formed. In each of the
states, the wrought workability is generally poor, and cracking,
breakage and the like are apt to occur in the working. When sulfide
particles are formed in this copper alloy, wrought workability is
further deteriorated, and working is made difficult. Since wrought
workability is affected by the size (average diameter) and the area
ratio of the sulfide particles, the size (average diameter) and the
area ratio of the sulfide particles are specifically defined in
this embodiment. Based on those, wrought workability and
machinability, which are not easily achieved at the same time in a
well balance, can be enhanced simultaneously in the
Cu--Ni--Si-based alloy.
[0043] The content of Ni is 1.5 to 7.0 mass %, and preferably 1.7
to 6.5 mass %. If the amount of Ni is too small, the degree of
precipitation hardening by the Ni--Si precipitate is small and the
mechanical strength is not sufficient. If the amount of Ni is too
large, which means that the amount is excessive, it leads not only
not to increase the amount of the Ni--Si precipitate that
contributes to the strength enhancement, but also to deteriorate
hot workability and cold workability (that is, ductility and
malleability) by forming a large amount of Ni--Si crystallized
product upon melt-casting, which are not preferable.
[0044] The content of Si is necessary in an amount of about 1/5 to
1/3 of the Ni content, on the basis of mass %, for the formation of
the Ni--Si precipitate (Ni.sub.2Si). Thus, in this embodiment, the
content of Si is 0.3 to 2.3 mass %, and preferably 0.34 to 2.2 mass
%.
<S>
[0045] In the copper alloy wrought material of this embodiment, it
is necessary that the size (average diameter) of the sulfide
particles be 0.1 to 10 .mu.m, and the sulfide particles be present
with an area ratio thereof in 0.1 to 10%. For this purpose, the
content of S is 0.02 to 1.0 mass %, and preferably 0.03 to 0.8 mass
%. If the content is too small, the area ratio of the sulfide
particles is small, and sufficient chip breakability and
separability may not be obtained. If the content of S is too large,
hot workability and cold workability (that is, ductility and
malleability) are deteriorated.
[0046] It is conventionally known that the amount of S is limited
to a trace amount in Corson alloys (Patent Literatures 10 and 11).
In this embodiment, this amount is daringly increased to a large
extent, while the amounts of other additive elements are set to be
within specific ranges, and the working is preferably carried out
under specific conditions. Thus, a copper alloy wrought material in
which sulfide particles have a predefined aspect ratio in the
wrought direction was obtained, and a good balance between the
machinability and the ductility and malleability is achieved.
[0047] Further, the copper alloy wrought material of this
embodiment may also contain one kind or two or more kinds of tin
(Sn), manganese (Mn), cobalt (Co), zirconium (Zr), titanium (Ti),
iron (Fe), chromium (Cr), aluminum (Al), phosphorus (P), and zinc
(Zn). These elements enhance the mechanical strength of the
Cu--Ni--Si alloy by forming solid solutions or precipitates, or
enhance machinability by forming sulfide particles. In the case of
containing any of these elements, it is preferable to contain one
kind or two or more kinds selected from Sn, Mn, Co, Zr, Ti, Fe, Cr,
Al, P and Zn in a total amount of 0.05 to 2.0 mass %. If the
content is smaller than 0.05 mass %, the alloy material containing
any of these elements is not much different from an alloy material
which does not contain these elements in terms the effect of
strength enhancement or machinability improvement. Further, if the
content is larger than 2.0 mass %, not only the effect of enhancing
mechanical strength and improving machinability is saturated, but
also the electrical conductivity is lowered, thus it is not
advantageous. Examples of the sulfide components include Cu--S,
Mn--S, Zr--S, Ti--S, Fe--S, Al--S, Cr--S, and Zn--S, and
particularly, the Cu--S-based sulfide is effective. There are also
sulfides composed of unavoidable impurities and S.
<Definition of Sulfide>
[0048] Examples of the sulfide components include Cu--S, Mn--S,
Zr--S, Ti--S, Fe--S, Al--S, Cr--S, and Zn--S. The sulfide is
preferably at least one selected from the group consisting of
Cu--S, Mn--S, Zr--S, Ti--S, Fe--S, Al--S, Cr--S, and Zn--S, and
particularly, Cu--S is effective. There are also sulfides composed
of unavoidable impurities and S. Herein, the term "Cu--S" means a
generic term for sulfides composed of Cu and S, such as Cu.sub.2S
and CuS, and the same is also applied to the term "Mn--S" or the
like.
[0049] Next, descriptions will be made on the definitions on the
size (average diameter) and area ratio of the sulfides, which are
compounds that contribute to enhancement of machinability, and
features thereof. Sulfide particles have an effect of finely
breaking and separating off the chips occurred upon the cutting,
and machinability is enhanced thereby. However, if the size
(average diameter) of the sulfide particles is smaller than 0.1
.mu.m, significant effects may not be obtained. Further, even if
there are sulfide particles having a size (average diameter) of 0.1
.mu.m or larger, if the total area ratio is small, chips are not
finely broken and separated off. Specifically, if sulfide particles
having a size (average diameter) of 0.1 .mu.m or larger are not
distributed at a density of 0.1 to 10% in terms of area ratio,
chips are not sufficiently broken and separated off. In addition,
since sulfides are soft, the sulfide particles may be extended
longitudinally depending on the working ratio at hot working or
cold working, but it is acceptable as long as the above-described
ranges of the size (average diameter) and area ratio of the sulfide
particles are satisfied in the cross-section perpendicular to the
longitudinal direction of the wrought material (transverse
cross-section). The size (average diameter) of the sulfide
particles is defined as the value obtained, by observing the
transverse cross-sections with an electron microscope, measuring
the sizes of 100 or more sulfide particles to convert those into
diameters of respective circles equivalent in areas, and averaging
the diameters. The area ratio of the sulfide particles is defined
as the value obtained, by counting the number of sulfide particles
seen in one visual field that is observed with an electron
microscope, determining the respective diameters of the individual
sulfide particles by converting the sizes into diameters of
respective circles equivalent in areas, averaging the diameters,
determining the area from the average diameter, determining the
total area of the sulfide particles per visual field by multiplying
the area by the number of sulfide particles, and dividing the
resultant total area of the sulfide particles by the total area of
one visual field.
[0050] On the other hand, sulfide deteriorates hot workability and
cold workability of a material. Since sulfide particles are apt to
be formed at the grain boundaries, to lower the grain boundary
strength, if the size (average diameter) of the sulfide particles
is too large, or if the area ratio is too large, the sulfide
particles cause cracking when the material is subjected to hot
working or cold working, to lead that the resultant material cannot
be used as a wrought material. Thus, it is necessary to limit the
size (average diameter) of the sulfide particles to 10 .mu.m or
less, and the area ratio of the sulfide particles to 10% or
less.
[0051] This size (average diameter) of the sulfide particles varies
depending onto the cooling speed at casting. If the cooling speed
is slow, the sulfide particles become larger, and on the contrary,
if the cooling speed is high, the sulfide particles become smaller.
The cooling speed is preferably 0.1 to 50.degree. C./second, and
more preferably 0.3 to 40.degree. C./second.
<Mechanical Properties and Production Conditions>
[0052] Next, description will be made on the mechanical properties
of the copper alloy wrought material in a preferred embodiment of
the first embodiment.
[0053] The copper alloy wrought material in this embodiment is
intended to substitute lead-containing phosphor bronze or beryllium
copper, that is, to substitute copper alloys containing
environmentally hazardous substances, and therefore, the copper
alloy wrought material needs to have a mechanical strength
equivalent to that of the wrought materials of these alloys.
Accordingly, the copper alloy wrought material is required to have
a tensile strength of 500 MPa or greater and an electrical
conductivity in terms of IACS (International Annealed Copper
Standard) of 25% IACS or higher, as the mechanical strength and
electrically conductivity that would not cause any problem in
practical use. The copper alloy in this embodiment is of
age-precipitation-type, and the mechanical strength and
electrically conductivity of the copper alloy are enhanced by
forming Ni.sub.2Si as described above. Thus, it is necessary that
the copper alloy contain Ni in an amount of 1.5 to 7.0 mass %, and
Si in an amount of 0.3 to 2.3 mass %. Further, the temperature at
the time of the solution treatment in the course of the production
process is preferably within the range of 750 to 1,000.degree. C.,
and the temperature at the time of aging is preferably within the
range of 350 to 600.degree. C.
[0054] In this embodiment, there are no particular limitations on
the method of producing the copper alloy wrought material, except
that the size (average diameter) of the sulfide particles is
controlled by setting the cooling speed at casting to the range
described above. For example, it is enough if the area of the
transverse cross-section of the ingot (cake or billet) is larger
than the area of the cross-section of the wrought material to be
produced. Since the copper alloy wrought material of this
embodiment is a wrought material of an age-precipitation-type
copper alloy, at least an aging heat treatment step is necessary
after the melt-casting step of the copper alloy raw material, but
the steps of hot working, annealing, and solution treatment, other
than the step(s) to obtain the copper alloy wrought material, may
be carried out optionally, if needed. For example, in regard to the
hot working step, it is possible to produce the copper alloy
wrought material of this embodiment through any one of the
production methods, such as hot extrusion of a billet, hot forging
of an ingot, and continuous casting. Further, there are no
particular limitations on the shape of the product, and it is
preferable to produce the product in a shape with which a copper
alloy part of the final form can be easily obtained by the
subsequent cutting step. That is, it is enough to produce a copper
alloy wrought material having a predetermined shape, such as wire,
rod, bar, sheet, or tube, in accordance with the application of the
copper alloy part, and to use the formed material appropriately.
For example, when the copper alloy part as the final form is a
screw, a rivet or the like, the shape of the copper alloy wrought
material is preferably a round rod shape.
[0055] Examples of the copper alloy part include parts, which
currently use lead-containing phosphor bronze or beryllium copper,
which require mechanical strength, electrically conductivity, heat
conductivity, and wear resistance, and which are produced in
complicated shapes mainly by cutting, for example, electronic
equipment parts, such as male pins and female pins of coaxial
connectors, barrel and plunger materials of the probes used in IC
sockets or battery terminal connectors, and connector terminals for
audio cables; structural parts, such as hinges of antennas,
fasteners, bearings, guide rails, resistance welders, and
timepieces; and element parts, such as cogwheels, bearings, and
ejector pins of molds. The "copper alloy part" of this embodiment
may also be a product which includes the copper alloy part produced
by cutting, as a part thereof.
Second Embodiment
<Ni and Si>
[0056] Also for the copper alloy wrought material of this
embodiment, the content ratio of Ni and Si is controlled. The
contents are the same as those in the first embodiment.
[0057] In a preferred embodiment of the copper alloy wrought
material of this embodiment, addition of sulfur (S) leads to the
formation of sulfide particles that contribute to enhancement of
machinability, in the matrix. This embodiment has a common feature
to the first embodiment, from the viewpoint that as these sulfide
particles serve as the starting points for the breakage and
separation off of chips when cutting is carried out, the chips
become to be apt to be finely broken and separated off, to enhance
machinability. Sulfide particles are formed upon casting, but when
once formed, a large portion of the sulfide particles are present
at the grain boundaries, to cause deterioration of hot workability
and cold workability (that is, ductility and malleability). Thus,
through wrought working and heat treatment, the sulfide particles
formed in the ingot (cake or billet) are made to exist in the
crystals of the matrix such that the area ratio of sulfide
particles in a cross-section that is in parallel to the wrought
direction would be 40% or higher, and sulfide particles having an
aspect ratio, as viewed from the wrought direction, in the
cross-section parallel to the wrought direction, of 1:1 to 1:100,
preferably 1:1 to 1:50, are dispersed in the matrix, chip
breakability and separability is enhanced, and hot workability and
cold workability are not impaired, to thereby that wrought working,
such as extrusion, rolling or drawing, is made possible. The copper
alloy in this embodiment is subjected to hot working or cold
working while being in the state in which nickel (Ni) and silicon
(Si) have formed a solid solution, or in the state in which a
Ni--Si precipitate has been formed. In each of the states, the
wrought workability is generally poor, and cracking, breakage and
the like are apt to occur in the working. When sulfide particles
are formed in this copper alloy, wrought workability is further
deteriorated, and working is made difficult. Since wrought
workability is largely affected by the position where the sulfide
particles exist, when a large amount of the sulfide particles are
made to exist in the crystals, ductility and malleability are
improved. In this embodiment, the area ratio of the sulfide
particles that exist in the grains is defined.
[0058] The content of Ni is 1.5 to 7.0 mass %, and preferably 1.7
to 6.5 mass %. If the amount of Ni is too small, the degree of
precipitation hardening by the Ni--Si precipitate is small and the
mechanical strength is not sufficient. If the amount of Ni is too
large, which means that the amount is excessive, it leads not only
not to increase the amount of the Ni--Si precipitate that
contributes to the strength enhancement, but also to deteriorate
hot workability and cold workability (that is, ductility and
malleability) by forming a large amount of Ni--Si crystallized
product upon melt-casting, which are not preferable.
[0059] The content of Si is necessary in an amount of about 1/5 to
1/3 of the Ni content, on the basis of mass %, for the formation of
the Ni--Si precipitate (Ni.sub.2Si). Thus, in this embodiment, the
content of Si is 0.3 to 2.3 mass %, and preferably 0.34 to 2.2 mass
%.
<S>
[0060] In the copper alloy wrought material of this embodiment, it
is necessary to make the sulfide particles thus formed to exist in
the crystals of the matrix in the cross-section that is in parallel
to the wrought direction, at an area ratio of 40% or larger, and to
control the aspect ratio of the sulfide particles in the
cross-section parallel to the wrought direction, to the ratio
described above. In order to achieve those, the content of S is set
to 0.02 to 1.0 mass %, and preferably 0.03 to 0.8 mass %. If this
content is too small, sufficient chip breakability and separability
is not obtained. If the content of S is too large, hot workability
and cold workability (that is, ductility and malleability) becomes
poor. It is preferable that the sulfide particles thus formed and
dispersed be present in the crystals of the matrix at an area ratio
of 50% or larger. This embodiment is also similar to the first
embodiment, from the viewpoint that S is actively contained in the
addition amount described above, which exceeds the general
upper-limit amount defined conventionally.
<Other Additive Elements>
[0061] The copper alloy wrought material of this embodiment may
also contain one kind or two or more kinds of tin (Sn), manganese
(Mn), cobalt (Co), zirconium (Zr), titanium (Ti), iron (Fe),
chromium (Cr), aluminum (Al), phosphorus (P), and zinc (Zn). The
effects, the ranges of preferable contents and the like of the
additive element are similar to those of the first embodiment.
<Definition of Sulfide>
[0062] Next, description will be made on the definitions on the
proportion of the sulfide particles, which are compounds to
contribute to enhancement of machinability, existing in the
crystals of the matrix in the cross-section parallel to the wrought
direction, and the aspect ratio of the sulfide particles, and
features thereof. The sulfide particles have an effect of finely
breaking separating off the chips occurred upon cutting, and
thereby machinability is enhanced. However, the position at which
the sulfide particles are present largely affects the ductility and
malleability (hot workability and cold workability). The proportion
of the sulfide particles that are present in the grains of the
matrix is the value obtained, by observing the cross-section
parallel to the wrought direction with an electron microscope,
counting the number of total sulfide particles observed in one
visual field, measuring the sizes of each sulfide particles to
convert those into diameters of the respective circles equivalent
in area, averaging the diameters, determining the area from the
average diameter, and multiplying the area by the number of sulfide
particles, to thereby determine the total area of total sulfide
particles seen in one visual field, subsequently counting only the
number of sulfide particles that are in the grains and across the
grain boundaries, measuring the sizes of each of said sulfide
particles to convert those into diameters of the respective circles
equivalent in area, averaging the diameters, determining the area
from the average diameter, and multiplying the area by the number
of said sulfide particles, to thereby determine the total area of
the sulfide particles that are present in the grains and across the
grain boundaries, and dividing the thus-determined total area by
the total area of all the sulfide particles seen in one visual
field. It is enough that this proportion of sulfide particles that
are present in the grains and across the grain boundaries is 40% or
higher. If the proportion is 40% or less, the ductility and
malleability become poor. In this case, the area ratio of the
sulfide particles is in the range of 0.1% to 20%, and preferably
0.1 to 10%. The area ratio of the sulfide particles is the value
obtained by dividing the total area of the sulfide particles seen
in one visual field, by the total area of one visual field.
[0063] Since sulfide particles are soft, the sulfide particles may
be extended longitudinally depending on the working ratio of hot
working or cold working, and are broken and separated, to be
dispersed in the matrix. In regard to the aspect ratio of the
dispersed sulfide particles, when the cross-section is observed
with an electron microscope, and the length t.sub.1 in the
direction perpendicular to the wrought direction is defined to be
1, the aspect ratio is designated as the ratio (t.sub.2/t.sub.1) of
the length t.sub.2 of the sulfide particles that are extended in
parallel to the wrought direction. If the aspect ratio is greater
than 1:100, there is a possibility that the defined content of S
may not be satisfied, and thus chips may not be finely broken and
separated upon cutting. Even in the case where the sulfide
particles do not have a shape that is linear in the wrought
direction, the definition does not change, and as shown in FIG. 4,
the aspect ratio is evaluated by determining the length t.sub.2 in
the wrought direction of the area occupying the region, and the
length t.sub.1 in the direction perpendicular to the length in the
wrought direction.
Measurement Examples for Sulfide Particles
[0064] FIG. 1(a) is a front view in which a copper alloy rod 10 is
viewed in parallel to the wrought direction R, and FIG. 1(b) is a
cross-sectional view, while 10a represents the cross-section,
illustrated schematically.
[0065] FIG. 2 is a schematic diagram of the electron microscopic
observation of the cross-section viewed in parallel to the wrought
direction, and shows grain boundaries 21 and the state of sulfide
particles, observed in one visual field. In the figure, 21
represents the grain boundary, 22 represents sulfide particle
present at the grain boundary, and 23 represents sulfide particle
present in the grain. Herein, the total area of all the sulfide
particles observed in one visual field is determined.
[0066] Next, FIG. 3 is a diagram schematically showing the
cross-sectional microstructure of a copper alloy rod viewed, with
an electron microscope (SEM), in parallel to the wrought direction,
and shows sulfide particles that are present in the grains, with
the grain boundaries, and the sulfide particles present at the
grain boundaries of FIG. 2 being excluded. The total area of the
sulfide particles that are present in the grains as shown in this
diagram is determined, and the proportion of the sulfide particles
that are present in the grains and the sulfide particles that are
seen in one visual field is determined. In this case, the area
ratio of the sulfide particles that are present in the grains is
61%.
[0067] The aspect ratio of a sulfide particle means, as shown in
FIG. 4, when the length t.sub.1 of the sulfide particle in the
direction perpendicular to the wrought direction is defined to be
1, the ratio of the length t.sub.2 of the sulfide particle that is
extended in parallel to the wrought direction, to the length in the
perpendicular direction (in the case of the lower example of the
drawing, 13).
<Mechanical Properties and Production Conditions>
[0068] Next, description will be made on the mechanical properties
of the copper alloy wrought material in a preferred embodiment of
this embodiment. The copper alloy in this embodiment is intended to
substitute lead-containing phosphor bronze or beryllium copper,
that is, to substitute copper alloys containing environmentally
hazardous substances, and therefore, this embodiment is similar to
the first embodiment from the viewpoint that the copper alloy needs
to have a mechanical strength equivalent to that of these alloys.
Accordingly, this embodiment is also similar to the first
embodiment in terms of the preferable ranges of the properties
(tensile strength, electrical conductivity) that are required for
practical use.
[0069] The method of producing the copper alloy wrought material of
this embodiment is primarily characterized in that the sulfide
particles that are present in a large amount at the grain
boundaries upon casting are made, through wrought working and heat
treatment, to exist in the crystals of the matrix such that the
area ratio of sulfide particles in the cross-section in parallel to
the wrought direction would be 40% or greater, and to disperse the
sulfide particles in the cross-section in parallel to the wrought
direction such that the aspect ratio would be in the range of 1:1
to 1:100.
[0070] Preferable examples of the wrought working and heat
treatment include the followings.
[0071] (a) The copper alloy is rapidly cooled after hot working,
followed by subjecting to area-reduction working at 0% to 95% (more
preferably 30 to 90%), and to a final aging treatment.
[0072] (b) After hot working, the copper alloy is subjected to cold
working and a heat treatment at a temperature of 600.degree. C. to
1,000.degree. C. repeatedly for one or more times, followed by
subjecting to a solution treatment before the final cold-working,
to area-reduction working at 0% to 95% (more preferably, 30 to
90%), and to a final aging treatment.
[0073] Herein, in the case where the cold working and the heat
treatment at a temperature of 600.degree. C. to 1,000.degree. C.
are respectively carried out once, the cold working is carried out
as the final cold-working, and the heat treatment at a temperature
of 600.degree. C. to 1,000.degree. C. is carried out as a solution
treatment.
[0074] Further, the area-reduction working is a cold working, and
the phrase "area-reduction working at 0%" means that the
area-reduction working is not carried out. The temperature of the
final aging treatment is preferably 350.degree. C. to 600.degree.
C., and more preferably 400.degree. C. to 550.degree. C.
[0075] The purpose of the heat treatment at a temperature of
600.degree. C. to 1,000.degree. C. is to enhance the workability of
the wrought material. The temperature range is preferably
800.degree. C. to 1,000.degree. C., and more preferably 900.degree.
C. to 1,000.degree. C. Further, the time period of the heat
treatment is preferably from 1 hour to 3 hours. The cooling
conditions are substantially arbitrary, and cooling may be carried
out in the manner of slow cooling or rapid cooling. The cooling
speed is sufficient if it is in the range of 0.1 to 1,000
C..degree. second.
[0076] The step immediately before the area-reduction working is
preferably a hot working or a solution treatment, from the
viewpoint that the control of the shape and the dispersion state of
the sulfide particles is appropriately conducted through the
area-reduction working, while the aspect ratio of the sulfide
particles in the cross-section in parallel to the wrought direction
is brought close to 1:1. In this case, the temperature of the hot
working or solution treatment is preferably 750.degree. C. to
1,000.degree. C., more preferably 850.degree. C. to 1,000.degree.
C., and even more preferably 900.degree. C. to 1,000.degree. C.
[0077] By conducting rapid cooling (water quenching or the like)
immediately after the hot working (hot rolling, hot drawing, hot
extrusion or the like), an effect equivalent to the solution
treatment can be obtained.
[0078] Since the copper alloy wrought material of this embodiment
is a wrought material of an age-precipitation-type copper alloy, it
is essential that the aging treatment step is preferably employed
at least after the step of melt-casting of the copper alloy raw
material, and other steps than the step to obtain the copper alloy
wrought material, such as the hot working step, an annealing step,
the solution treatment step, and the heat treatment step at a
temperature of 600.degree. C. to 1,000.degree. C., are carried out
optionally, if needed. For example, in regard to the hot working
step, it is possible to produce the copper alloy wrought material
of this embodiment through any one of the usual production methods,
such as hot extrusion of a billet, hot forging of an ingot, and
continuous casting.
[0079] In addition to the above, preferred examples of the shape of
the product or the copper alloy part may be similar to those of the
first embodiment described above.
EXAMPLES
[0080] The present invention will be described in more detail based
on examples given below, but the invention is not meant to be
limited by these.
Example 1
Example 1-1
[0081] Each of copper alloys of the respective composition having
alloying elements as shown in Table 1-1 was melted in a high
frequency melting furnace, followed by casting the respective
billet at the cooling speed of 0.5 to 5.degree. C./second. The
diameter of the billet was set to 200 mm. The resultant billet was
hot extruded at 950.degree. C., immediately followed by water
quenching, to obtain a round bar with diameter 20 mm. Then, the
resultant round rod was subjected to cold drawing, to obtain a
round rod with diameter 10 mm, followed by subjecting to an aging
heat treatment at a temperature of 450.degree. C. for 2 hours.
[0082] With respect to the resultant samples of each of the
thus-obtained copper alloy wrought materials (round rods), [1]
tensile strength, [2] electrical conductivity, and [3]
machinability were investigated by the following methods.
Measurement methods of each evaluation item are described
below.
[1] Tensile Strength (TS)
[0083] The tensile strength of each of three samples was measured
in accordance with JIS Z 2241, and its average value (MPa) was
obtained and shown.
[2]]Electrical Conductivity (EC)
[0084] The electrical conductivity of each of two samples was
measured in a thermostatic bath controlled at 20.degree. C.
(.+-.1.degree. C.) by using a four-terminal method, and its average
value (% IACS) was obtained and shown.
[3] Machinability
[0085] Stepwise cutting was conducted to cut the outer diameter of
the round rod using a general lathe, to produce a rivet with
diameter 9.6 mm at the major diameter portion and diameter 8 mm at
the minor diameter portion. The shapes of the respective chips thus
occurred were observed. Chips that were broken and separated off at
a length of 5 mm or less were judged to be "good"; chips that were
broken and separated off but had a length of 5 mm or longer but 10
mm or shorter were judged to be "fair"; and chips that were
connected in a helical shape were judged to be "poor". The grades
that do not cause any problem in practical use are "good" and
"fair". The cutting conditions were: the rotation speed at 1,010
rpm, the conveyance speed at 0.1 mm per rotation, and the notch
margin at 0.2 mm. An ultra-hard bit was used, and no cutting oil
was used.
[0086] Further, the size (average diameter) and the area ratio of
the sulfide particles were determined, by observing the
microstructure of the respective sample of the round rod with
diameter 10 mm on any three transverse cross-sections, under a
scanning electron microscope (SEM), in three visual fields,
respectively. The size (average diameter) of the sulfide particles
was determined, by measuring the sizes of 100 or more sulfide
particles per visual field to convert those into diameters of
respective circles equivalent in areas, and averaging the
diameters. The area ratio of the sulfide particles was determined,
by counting the number of sulfide particles seen in one visual
field, determining the area of an individual sulfide particle from
the average diameter converted from the size into a diameter of a
circle equivalent in area, multiplying the area by the number to
determine the total area of the sulfide particles per visual field,
and dividing the total area by the area of one visual field.
Further, the alloying elements of the sulfide particles were
analyzed, by using an energy dispersive fluorescent X-ray analyzer
(EDX) attached to the SEM.
[0087] The results are shown in Table 1-1. In Examples 1-1 to 1-25,
the contents of the alloying elements were within the range
according to the present invention, and all of the working examples
satisfied the conditions of tensile strength 500 MPa or greater and
electrical conductivity 25% IACS or higher. Further, the size
(average diameter) of the sulfide particles was 0.1 to 10 .mu.m,
and the area ratio of the sulfide particles satisfied the range of
0.1 to 10%, while the working examples had no cracking upon
material working and had satisfactory machinability.
[0088] Comparative examples 1-1 to 1-9 are comparative examples in
which the contents of the alloying elements were outside of the
range as defined in the present invention. Comparative examples 1-1
and 1-3 had a low Ni content and a low Si content, and was poor in
the tensile strength. Comparative example 1-2 had a high Ni content
and a high Si content, and was poor in the electrical conductivity.
Comparative example 1-4 had a high Ni content and a high Si
content, and cracking was occurred in the cold working. Comparative
example 1-5 had a low S content and a small area ratio of sulfide
particles, and was poor in the machinability. Comparative examples
1-6 and 1-7 had a high S content and a large area ratio of sulfide
particles, and cracking was occurred in the hot working.
Comparative examples 1-8 and 1-9 had the total amount of Sn, Mn,
Co, Zr, Ti, Fe, Cr, Al, P and Zn greater than 2.0 mass %, and was
poor in the electrical conductivity.
[0089] Conventional examples 1-1 and 1-2 are free cutting phosphor
bronze and free cutting beryllium copper. The copper alloy wrought
materials of Examples can exhibit properties that are equivalent or
superior to those of Conventional examples 1-1 and 1-2, without
containing any environmentally hazardous substances which are
contained in the materials of Conventional examples 1-1 and
1-2.
TABLE-US-00001 TABLE 1-1 Alloy composition (mass %) Total amount of
Sn Name Ni Si S Sn Mn Co Zr Ti Fe Cr Al P Zn to Zn Cu Example 1-1
1.5 0.37 0.69 0.00 Balance Example 1-2 1.8 0.46 0.26 0.00 Balance
Example 1-3 2.3 0.54 0.46 0.00 Balance Example 1-4 2.8 0.69 0.14
0.26 0.26 Balance Example 1-5 3.3 0.84 0.21 0.08 0.08 Balance
Example 1-6 3.8 0.96 0.12 0.11 0.11 Balance Example 1-7 4.2 1.12
0.29 0.13 0.13 Balance Example 1-8 4.8 1.30 0.31 0.11 0.11 Balance
Example 1-9 5.5 1.36 0.18 0.13 0.08 0.21 Balance Example 1-10 6.3
1.53 0.22 0.24 0.09 0.33 Balance Example 1-11 7.0 1.96 0.27 0.15
0.16 0.31 Balance Example 1-12 2.2 0.55 0.28 0.08 0.11 0.19 Balance
Example 1-13 2.7 0.73 0.25 0.07 0.22 0.29 Balance Example 1-14 3.2
0.83 0.03 0.15 0.18 0.33 Balance Example 1-15 3.7 0.93 0.11 0.09
0.13 0.22 Balance Example 1-16 1.6 0.34 0.98 0.23 0.23 Balance
Example 1-17 2.4 0.57 0.31 0.05 0.11 0.63 0.79 Balance Example 1-18
2.7 0.75 0.18 0.08 0.04 0.12 Balance Example 1-19 3.3 0.82 0.23
0.21 0.35 0.56 Balance Example 1-20 3.7 0.95 0.09 0.16 0.10 0.26
Balance Example 1-21 5.8 1.28 0.08 0.22 0.18 0.05 0.02 0.47 Balance
Example 1-22 6.5 1.77 0.11 0.10 0.14 0.21 0.38 0.83 Balance Example
1-23 2.3 0.55 0.08 0.22 0.08 0.12 0.11 0.39 0.92 Balance Example
1-24 1.8 0.49 0.42 0.12 0.18 0.17 0.05 0.72 1.24 Balance Example
1-25 3.1 0.79 0.26 0.12 0.19 0.13 0.08 0.08 0.02 0.43 1.05 Balance
Comparative 1.3 0.29 0.21 0.00 Balance example 1-1 Comparative 7.5
2.31 0.25 0.08 0.08 Balance example 1-2 Comparative 1.4 0.29 0.31
0.18 0.18 Balance example 1-3 Comparative 7.8 2.45 0.19 0.27 0.27
Balance example 1-4 Comparative 3.2 0.82 0.01 0.24 0.17 0.41
Balance example 1-5 Comparative 3.1 0.80 1.08 0.18 0.18 Balance
example 1-6 Comparative 3.7 0.94 1.22 0.24 0.15 0.39 Balance
example 1-7 Comparative 3.3 0.80 0.25 0.53 0.12 0.28 0.25 0.42 0.64
2.24 Balance example 1-8 Comparative 2.7 0.68 0.54 0.86 0.21 0.18
0.08 0.71 2.04 Balance example 1-9 Conventional Sn:0.4, Zn:0.4,
Pb:4.0, P:0.1 (free-cutting phosphor bronze) Balance example 1-1
Conventional Be:1.9, Pb:0.4, Ni + Co:0.4 (free-cutting beryllium
copper) Balance example 1-2 Size of Area ratio Component sulfide of
sulfide of particles particles TS EC Name sulfide (.mu.m) (%) (MPa)
(% IACS) Machinability Example 1-1 Cu--S 4.6 5.5 515 39.3 Good
Example 1-2 Cu--S 2.3 1.9 603 38.2 Good Example 1-3 Cu--S 2.9 3.8
712 39.5 Good Example 1-4 Cu--S 1.8 1.1 810 35.3 Good Example 1-5
Cu--S 1.6 1.5 864 35.9 Good Example 1-6 Cu--S 1.4 0.8 942 35.6 Good
Example 1-7 Cu--S, Mn--S 3.1 2.4 961 31.0 Good Example 1-8 Cu--S,
Mn--S 2.5 2.7 983 30.0 Good Example 1-9 Cu--S 1.7 1.3 996 35.7 Good
Example 1-10 Cu--S, Mn--S 2.1 2.0 987 33.3 Good Example 1-11 Cu--S,
Mn--S 2.6 2.3 1,011 25.3 Good Example 1-12 Cu--S, Zr--S 1.8 2.2 692
37.4 Good Example 1-13 Cu--S, Ti--S 2.0 2.0 781 35.2 Good Example
1-14 Cu--S 0.9 0.3 858 34.4 Fair Example 1-15 Cu--S 1.3 0.8 913
28.0 Good Example 1-16 Cu--S, Mn--S 5.1 7.7 559 32.5 Good Example
1-17 Cu--S, Al--S, Zn--S 2.6 2.8 726 36.2 Good Example 1-18 Cu--S,
Cr--S 1.6 1.7 771 30.7 Good Example 1-19 Cu--S, Fe--S, Zn--S 1.9
2.0 856 25.2 Good Example 1-20 Cu--S 1.2 0.5 921 28.3 Fair Example
1-21 Cu--S, Mn--S 1.3 0.8 994 28.8 Good Example 1-22 Cu--S, Mn--S
1.7 1.1 1,018 26.2 Good Example 1-23 Cu--S, Zr--S 1.2 0.5 731 28.4
Fair Example 1-24 Cu--S, Mn--S, Ti--S, Zn--S 2.9 3.8 602 29.3 Good
Example 1-25 Cu--S, Mn--S, Zr--S, Al--S 2.2 2.4 842 28.3 Good
Comparative Cu--S 1.8 1.9 441 39.0 Good example 1-1 Comparative
Cu--S 2.5 2.0 971 21.4 Good example 1-2 Comparative Cu--S 2.7 2.7
469 35.7 Good example 1-3 Comparative Cu--S, Mn--S 1.9 1.5 Cracked
in cold working example 1-4 Comparative Cu--S 0.9 0.08 867 30.4
Poor example 1-5 Comparative Cu--S 5.9 10.5 Cracked in hot working
example 1-6 Comparative Cu--S, Mn--S, Zr--S 6.2 11.2 Cracked in hot
working example 1-7 Comparative Cu--S, Zr--S, Ti--S 2.2 2.0 905
17.4 Good example 1-8 Comparative Cu--S, Mn--S, Cr--S, Al--S 3.6
4.3 776 18.7 Good example 1-9 Conventional None (Pb particles)
Pb:4.7 1.3 475 15.3 Good example 1-1 Conventional None (Pb
particles) Pb:2.8 0.1 1,130 23.4 Good example 1-2
Example 1-2
[0090] Small-sized ingots were produced, with the alloying elements
of Example 1-6 and Example 1-16 in Table 1-1, using a small-sized
mold (25 mm.times.25 mm.times.300 mm) for laboratory use, while the
cooling speed at casting was changed, for example, by changing the
preheating temperature of the mold. The ingots thus obtained were
subjected to hot rolling at a temperature of 950.degree. C.,
immediately followed by water quenching, to obtain round rods with
diameter 20 mm, respectively. Then, the resultant round rods were
subjected to cold drawing, to obtain round rods with diameter 10
mm, followed by subjecting to an aging heat treatment at a
temperature of 450.degree. C. for 2 hours. With respect to the
respective samples of the copper alloy wrought materials (round
rods) obtained as above, [1] tensile strength, [2] electrical
conductivity, and [3] machinability were examined in the same
manner as in Example 1-1, and the size (average diameter) and the
area ratio of the sulfide particles were also similarly determined
by the methods described above. The results are shown in Table
1-2.
TABLE-US-00002 TABLE 1-2 Alloy composition (mass %) Name Ni Si S Sn
Mn Cu Example 3.8 0.96 0.12 0.11 Balance 1-26 Example 3.8 0.96 0.12
0.11 Balance 1-27 Example 3.8 0.96 0.12 0.11 Balance 1-28 Example
3.8 0.96 0.12 0.11 Balance 1-29 Example 1.6 0.34 0.98 0.23 Balance
1-30 Example 1.6 0.34 0.98 0.23 Balance 1-31 Example 1.6 0.34 0.98
0.23 Balance 1-32 Example 1.6 0.34 0.98 0.23 Balance 1-33
Comparative 3.8 0.96 0.12 0.11 Balance example 1-10 Comparative 3.8
0.96 0.12 0.11 Balance example 1-11 Comparative 1.6 0.34 0.98 0.23
Balance example 1-12 Comparative 1.6 0.34 0.98 0.23 Balance example
1-13 Area Size ratio of of Cooling Component sulfide sulfide speed
of particles particles TS EC Machin- Name (.degree. C./sec.)
sulfide (.mu.m) (%) (MPa) (% IACS) ability Example 0.1 Cu--S 9.6
0.9 948 36.1 Fair 1-26 Example 2 Cu--S 1.4 0.8 952 35.7 Good 1-27
Example 11 Cu--S 0.6 0.8 950 35.6 Good 1-28 Example 45 Cu--S 0.1
0.7 936 35.3 Fair 1-29 Example 0.2 Cu--S, Mn--S 9.2 7.8 572 32.1
Good 1-30 Example 1 Cu--S, Mn--S 4.0 7.8 566 32.6 Good 1-31 Example
10 Cu--S, Mn--S 1.2 7.6 562 31.7 Good 1-32 Example 48 Cu--S, Mn--S
0.3 7.3 558 31.3 Good 1-33 Comparative 0.09 Cu--S 10.7 0.9 Cracked
in cold working example 1-10 Comparative 59 Cu--S 0.06 0.5 942 35.1
Poor example 1-11 Comparative 0.08 Cu--S, Mn--S 15.3 8.0 Cracked in
hot working example 1-12 Comparative 65 Cu--S, Mn--S 0.08 7.2 574
31.7 Poor example 1-13
[0091] In Table 1-2, Examples 1-26 to 1-29 are working examples
produced with the same alloying elements as those in Example 1-6
and Examples 1-30 to 1-33 are working examples produced with the
same alloying elements as those in Example 1-16, each by changing
the cooling speed in the range according to the present invention.
When the cooling speed is made fast, the size (average diameter) of
the sulfide particles tends to be small, but all of the working
examples satisfied the values within the range according to the
present invention, to exhibit excellent machinability. In Table
1-2, Comparative examples 1-10 and 1-11 are comparative examples
produced with the same alloying elements as those in Example 1-6
and Comparative examples 1-12 and 1-13 are comparative examples
produced with the same alloying elements as those in Example 1-16,
each by setting the cooling speed outside of the range defined in
the present invention. When the cooling speed was slow (Comparative
examples 1-10 and 1-12), the size (average diameter) of the sulfide
particles become large, and cracking was occurred in the cold
working or hot working. When the cooling speed was fast
(Comparative examples 1-11 and 1-13), the size (average diameter)
of the sulfide particles was less than 0.1 .mu.m, and the
machinability was poor.
Example 1-3
[0092] Round rods with diameter .phi.2 mm and .phi.7 mm,
respectively, were obtained, from the round rods with diameter 10
mm which were obtained by the method in Example 1-1, using the
alloying elements of Example 1-6 and Example 1-16 in Table 1-1,
respectively. Using the thus-obtained round rods, 1,000 connector
pins, as shown in FIG. 5 and FIG. 6, respectively, were obtained by
using an NC lathe. As a result, working into the parts was able to
carry out, without any twining of chips to the worked parts, and
without any changes in the dimension due to tool abrasion. The
outer diameter working conditions were: the rotation speed at 3,000
rpm, and the conveyance speed at 0.02 mm per rotation; and the
drilling conditions were: the rotation speed at 2,500 rpm, and the
conveyance speed at 0.03 mm per rotation, and a cutting oil was
used. In FIG. 5, 50 represents a connector pin, and 51 represents a
slit. In FIG. 6, 60 represents a connector pin of another form, 61
represents a slit, and 62 represents a tapering section.
[0093] With respect to the connector pin with the shape of FIG. 5,
evaluation was made on the insertion/extraction property that is
required as a characteristic of a pin material. The evaluation
method was as follows: a pin gauge with diameter .phi.0.92 mm was
inserted into the pin worked above, and the insertion/extraction
force (initial value T0) was measured; then, the same pin was
repeatedly subjected to inserting and extracting for 500 times, and
the insertion/extraction force (T1) was measured again; and the
ratio to the initial value, T1/T0, was determined. it can be said
that the larger the value of T1/T0 is, the smaller the lowering in
the insertion/extraction force is, which is satisfactory in the
performance as a connector pin. The evaluation was made with five
pins, and the average value was determined. For comparison, the
same evaluation was carried out with respect to the materials of
Conventional examples 1-1 and 1-2 in Table 1-1. The results are
shown in Table 1-3.
[0094] It can be seen from Table 1-3 that Examples exhibit
insertion/extraction property that are equivalent to that of free
cutting beryllium copper of Conventional example 1-2, and that they
are excellent connector pins. The insertion/extraction property of
free cutting phosphor bronze of Conventional example 1-1 was
inferior to that of Examples, with resulting in that there is a
concern for contact failure upon a long-term use.
TABLE-US-00003 TABLE 1-3 Evaluation of insertion/extraction
property Name (T1/T0) Example 1-6 0.86 Example 1-16 0.80
Conventional example 1-1 0.53 Conventional example 1-2 0.85
Example 2
Example 2-1
[0095] Samples were obtained in the same manner as in Example 1-1,
using copper alloys of the respective composition having alloying
elements as shown in Table 2-1. The measurement methods and
conditions for the properties were also the same as those in
Example 1-1.
[0096] The area ratio of the sulfide particles that were present in
the crystals of the matrix in the cross-section in parallel to the
wrought direction, was determined, by observing the microstructure
of the respective sample of round rod with diameter 10 mm on any
three cross-sections each in parallel to the wrought direction,
under a scanning electron microscope (SEM), in three visual fields,
respectively. That is, the area ratio was determined, by counting
the number of total sulfide particles observed in one visual field,
measuring the sizes of each sulfide particles to convert those into
diameters of the respective circles equivalent in area, averaging
the diameters, determining the area from the average diameter, and
multiplying the area by the number of sulfide particles, to thereby
determine the total area of total sulfide particles seen in one
visual field, subsequently counting only the number of sulfide
particles that were in the grains and across the grain boundaries,
measuring the sizes of each of said sulfide particles to convert
those into diameters of the respective circles equivalent in area,
averaging the diameters, determining the area from the average
diameter, and multiplying the area by the number of said sulfide
particles, to thereby determine the total area of the sulfide
particles that were present in the grains and across the grain
boundaries, and dividing the thus-determined total area by the
total area of all the sulfide particles seen in one visual field.
Further, the alloying elements of the sulfide particles were
analyzed, by using an energy dispersive fluorescent X-ray analyzer
(EDX) attached to the SEM. Please note, although not shown in the
table, that the wrought materials of Examples each had the aspect
ratio in the cross-section that was in parallel to the wrought
direction, within the range of 1:1 to 1:100, and that the area
ratio of the sulfide particles in the transverse cross-section of
the wrought materials satisfied the requirement of 0.1 to 10%.
[0097] The results are shown in Table 2-1. In Examples 2-1 to 2-25,
the contents of the alloying elements were within the range
according to the present invention, and all of the working examples
satisfied the conditions of tensile strength 500 MPa or greater and
electrical conductivity 25% IACS or higher. Further, 40% or more of
sulfide particles in the cross-section in parallel to the wrought
direction were present in the crystals of the matrix, while the
working examples had no cracking upon material working and had
satisfactory machinability.
[0098] Comparative examples 2-1 to 2-9 are comparative examples in
which the respective alloy composition was outside of the range as
defined in the present invention. Comparative examples 2-1 and 2-3
was too low in the Ni content and Si content, resulted in an
insufficient tensile strength. Comparative example 2-2 was too high
in the Ni content and the Si content, and was poor in the
electrical conductivity. Comparative example 2-4 was too high in
the Ni content and the Si content, and cracking was occurred in the
cold working. Comparative example 2-5 had a low S content, and 40%
or more of the sulfide particles in the cross-section in parallel
to the wrought direction were present in the crystals of the
matrix, but the machinability was poor. Comparative examples 2-6
and 2-7 had a high S content, and 40% or more of the sulfide
particles in the cross-section in parallel to the wrought direction
were not present in the crystals of the matrix, and cracking was
occurred in the hot working. Comparative examples 2-8 and 2-9 had
the total amount of Sn, Mn, Co, Zr, Ti, Fe, Cr, Al, P and Zn
greater than 2.0 mass %, and was poor in the electrical
conductivity.
[0099] Conventional examples 2-1 and 2-2 are free cutting phosphor
bronze and free cutting beryllium copper. The copper alloy wrought
materials of Examples can exhibit properties that are equivalent or
superior to those of Conventional examples 2-1 and 2-2, without
containing any environmentally hazardous substances which are
contained in the materials of Conventional examples 2-1 and
2-2.
TABLE-US-00004 TABLE 2-1 Alloy composition (mass %) Total amount of
Sn Name Ni Si S Sn Mn Co Zr Ti Fe Cr Al P Zn to Zn Cu Example 2-1
1.5 0.37 0.69 0.00 Balance Example 2-2 1.8 0.46 0.26 0.00 Balance
Example 2-3 2.3 0.54 0.46 0.00 Balance Example 2-4 2.8 0.69 0.14
0.26 0.26 Balance Example 2-5 3.3 0.84 0.21 0.08 0.08 Balance
Example 2-6 3.8 0.96 0.12 0.11 0.11 Balance Example 2-7 4.2 1.12
0.29 0.13 0.13 Balance Example 2-8 4.8 1.30 0.31 0.11 0.11 Balance
Example 2-9 5.5 1.36 0.18 0.13 0.08 0.21 Balance Example 2-10 6.3
1.53 0.22 0.24 0.09 0.33 Balance Example 2-11 7.0 1.96 0.27 0.15
0.16 0.31 Balance Example 2-12 2.2 0.55 0.28 0.08 0.11 0.19 Balance
Example 2-13 2.7 0.73 0.25 0.07 0.22 0.29 Balance Example 2-14 3.2
0.83 0.03 0.15 0.18 0.33 Balance Example 2-15 3.7 0.93 0.11 0.09
0.13 0.22 Balance Example 2-16 1.6 0.34 0.98 0.23 0.23 Balance
Example 2-17 2.4 0.57 0.31 0.05 0.11 0.63 0.79 Balance Example 2-18
2.7 0.75 0.18 0.08 0.04 0.12 Balance Example 2-19 3.3 0.82 0.23
0.21 0.35 0.56 Balance Example 2-20 3.7 0.95 0.09 0.16 0.10 0.26
Balance Example 2-21 5.8 1.28 0.08 0.22 0.18 0.05 0.02 0.47 Balance
Example 2-22 6.5 1.77 0.11 0.10 0.14 0.21 0.38 0.83 Balance Example
2-23 2.3 0.55 0.08 0.22 0.08 0.12 0.11 0.39 0.92 Balance Example
2-24 1.8 0.49 0.42 0.12 0.18 0.17 0.05 0.72 1.24 Balance Example
2-25 3.1 0.79 0.26 0.12 0.19 0.13 0.08 0.08 0.02 0.43 1.05 Balance
Comparative 1.3 0.29 0.21 0.00 Balance example 2-1 Comparative 7.5
2.31 0.25 0.08 0.08 Balance example 2-2 Comparative 1.4 0.29 0.31
0.18 0.18 Balance example 2-3 Comparative 7.8 2.45 0.19 0.27 0.27
Balance example 2-4 Comparative 3.2 0.82 0.01 0.24 0.17 0.41
Balance example 2-5 Comparative 3.1 0.80 1.08 0.18 0.18 Balance
example 2-6 Comparative 3.7 0.94 1.22 0.24 0.15 0.39 Balance
example 2-7 Comparative 3.3 0.80 0.25 0.53 0.12 0.28 0.25 0.42 0.64
2.24 Balance example 2-8 Comparative 2.7 0.68 0.54 0.86 0.21 0.18
0.08 0.71 2.04 Balance example 2-9 Conventional Sn:0.4, Zn:0.4,
Pb:4.0, P:0.1 (free-cutting phosphor bronze) Balance example 2-1
Conventional Be:1.9, Pb:0.4, Ni + Co:0.4 (free-cutting beryllium
copper) Balance example 2-2 Area ratio of sulfide particles TS EC
Name Component of sulfide in gains (%) (MPa) (% IACS) Machinability
Example 2-1 Cu--S 61 515 39.3 Good Example 2-2 Cu--S 55 603 38.2
Good Example 2-3 Cu--S 53 712 39.5 Good Example 2-4 Cu--S 50 810
35.3 Good Example 2-5 Cu--S 62 864 35.9 Good Example 2-6 Cu--S 58
942 35.6 Good Example 2-7 Cu--S, Mn--S 57 961 31.0 Good Example 2-8
Cu--S, Mn--S 54 983 30.0 Good Example 2-9 Cu--S 58 996 35.7 Good
Example 2-10 Cu--S, Mn--S 55 987 33.3 Good Example 2-11 Cu--S,
Mn--S 60 1,011 25.3 Good Example 2-12 Cu--S, Zr--S 50 692 37.4 Good
Example 2-13 Cu--S, Ti--S 62 781 35.2 Good Example 2-14 Cu--S 48
858 34.4 Fair Example 2-15 Cu--S 58 913 28.0 Good Example 2-16
Cu--S, Mn--S 55 559 32.5 Good Example 2-17 Cu--S, Al--S, Zn--S 63
726 36.2 Good Example 2-18 Cu--S, Cr--S 50 771 30.7 Good Example
2-19 Cu--S, Fe--S, Zn--S 55 856 25.2 Good Example 2-20 Cu--S 44 921
28.3 Fair Example 2-21 Cu--S, Mn--S 61 994 28.8 Good Example 2-22
Cu--S, Mn--S 53 1,018 26.2 Good Example 2-23 Cu--S, Zr--S 52 731
28.4 Fair Example 2-24 Cu--S, Mn--S, Ti--S, Zn--S 52 602 29.3 Good
Example 2-25 Cu--S, Mn--S, Zr--S, Al--S 61 842 28.3 Good
Comparative Cu--S 62 441 39.0 Good example 2-1 Comparative Cu--S 54
971 21.4 Good example 2-2 Comparative Cu--S 59 469 35.7 Good
example 2-3 Comparative Cu--S, Mn--S 55* Cracked in cold working
example 2-4 Comparative Cu--S 63 867 30.4 Poor example 2-5
Comparative Cu--S 35* Cracked in hot working example 2-6
Comparative Cu--S, Mn--S, Zr--S 33* Cracked in hot working example
2-7 Comparative Cu--S, Zr--S, Ti--S 57 905 17.4 Good example 2-8
Comparative Cu--S, Mn--S, Cr--S, Al--S 50 776 18.7 Good example 2-9
Conventional Pb particles 475 15.3 Good example 2-1 Conventional Pb
particles 1,130 23.4 Good example 2-2 *The area ratio of sulfide
particles in grains, in the samples cracked 515
Example 2-2
[0100] Copper alloys having the compositions of Examples 2-1, 2-6
and 2-16 and Comparative example 2-5 in Table 2-1 were melted in a
high frequency melting furnace, respectively, and billets with
diameter 300 mm were obtained by casting at a cooling speed of
1.degree. C./second, respectively. The respective billet was hot
extruded at a temperature of 950.degree. C., immediately followed
by water quenching, to obtain a round rod with diameter 30 mm.
Then, the resultant round rod was worked to diameter 20 mm by cold
drawing, followed by subjecting to a solution treatment at a
temperature of 950.degree. C., to obtain a round rod with diameter
20 mm.
[0101] The thus-obtained round rod was subjected to area-reduction
working, to obtain a round rod with diameter 20 mm (an
area-reduction working 0%), a round rod with diameter 16 mm (an
area-reduction working 36.0%), a round rod with diameter 10 mm (an
area-reduction working 75.0%), a round rod with diameter 4.5 mm (an
area-reduction working 94.9%), and a round rod with diameter 3.5 mm
(an area-reduction working 96.9%), respectively. Further, the
resultant round rods were subjected to an aging treatment as
follows: the round rod with diameter 20 mm was treated at
500.degree. C. for 2 hours; the round rod with diameter 16 mm was
treated at 480.degree. C. for 2 hours; the round rod with diameter
10 mm was treated at 450.degree. C. for 2 hours; and the round rods
with diameter 4.5 mm and 3.6 mm were treated at 430.degree. C. for
2 hours. With respect to the thus-obtained samples of the copper
alloy wrought materials (round rods), [1] tensile strength and [2]
electrical conductivity were examined in the same manner as in
Example 1, and [3] machinability was examined by the following
method.
[3] Machinability
[0102] The materials with the respective diameters were subjected
to external cutting, using a general lathe, to obtain round rods
with diameter 3 mm, followed by stepwise cutting to cut the outer
diameter of the round rods. The shapes of the respective chips thus
occurred were observed. Chips that were broken and separated off at
a length of 5 mm or less were judged to be "good"; chips that were
broken and separated off but had a length of 5 mm or longer but 10
mm or shorter were judged to be "fair"; and chips that were
connected in a helical shape were judged to be "poor". The grades
that do not cause any problem in practical use are "good" and
"fair". The cutting conditions were: the rotation speed at 1,010
rpm, the conveyance speed at 0.1 mm per rotation, and the notch
margin at 0.2 mm. An ultra-hard bit was used, and no cutting oil
was used.
[0103] The area ratio of the sulfide particles in the cross-section
in parallel to the wrought direction and present in the crystals of
the matrix, was determined, by the method described above, by
observing the microstructure of the respective sample of round rod
with diameter of 20, 16, 10, 4.5, or 3.5 mm on any three
cross-sections each in parallel to the wrought direction, under a
scanning electron microscope (SEM), in three visual fields,
respectively. Further, the aspect ratio of the sulfide particles
was determined from the ratio of the length of the sulfide
particles that were extended in parallel to the wrought direction,
while the length in the direction perpendicular to the wrought
direction of the sulfide particles observed with the electron
microscope was defined to be 1.
TABLE-US-00005 TABLE 2-2 Working ratio in area- Alloy composition
(mass %) reduction Name Ni Si S Sn Mn Cu (%) Example 2-26 1.5 0.37
0.69 Balance 0.0 Example 2-27 1.5 0.37 0.69 Balance 36.0 Example
2-28 1.5 0.37 0.69 Balance 75.0 Example 2-29 1.5 0.37 0.69 Balance
94.9 Example 2-30 3.8 0.96 0.12 0.11 Balance 0.0 Example 2-31 3.8
0.96 0.12 0.11 Balance 36.0 Example 2-32 3.8 0.96 0.12 0.11 Balance
75.0 Example 2-33 3.8 0.96 0.12 0.11 Balance 94.9 Example 2-34 1.6
0.34 0.98 0.23 Balance 0.0 Example 2-35 1.6 0.34 0.98 0.23 Balance
36.0 Example 2-36 1.6 0.34 0.98 0.23 Balance 75.0 Example 2-37 1.6
0.34 0.98 0.23 Balance 94.9 Reference comparative 1.5 0.37 0.69
Balance 97.0 example 2-1 Reference comparative 3.8 0.96 0.12 0.11
Balance 97.0 example 2-2 Reference comparative 1.6 0.34 0.98 0.23
Balance 97.0 example 2-3 Reference comparative 3.2 0.82 0.01 0.24
0.17 Balance 0.0 example 2-4 Reference comparative 3.2 0.82 0.01
0.24 0.17 Balance 36.0 example 2-5 Reference comparative 3.2 0.82
0.01 0.24 0.17 Balance 75.0 example 2-6 Reference comparative 3.2
0.82 0.01 0.24 0.17 Balance 97.0 example 2-7 Area ratio of sulfide
particles in grains Aspect TS EC Machin- Name (%) ratio (MPa) (%
IACS) ability Example 2-26 55 1:1 to 1:3 504 37.5 Good Example 2-27
62 1:1 to 1:9 522 34.5 Good Example 2-28 61 1:1 to 1:60 515 39.3
Good Example 2-29 53 1:1 to 1:72 580 33.0 Good Example 2-30 57 1:1
to 1:4 890 34.5 Good Example 2-31 60 1:1 to 1:15 896 33.4 Good
Example 2-32 58 1:1 to 1:78 942 35.6 Good Example 2-33 59 1:1 to
1:80 954 35.0 Good Example 2-34 60 1:1 to 1:5 526 30.3 Good Example
2-35 55 1:1 to 1:20 550 30.8 Good Example 2-36 55 1:1 to 1:71 559
32.5 Good Example 2-37 49 1:1 to 1:95 606 32.4 Good Reference
comparative Cracked in cold working example 2-1 Reference
comparative Cracked in cold working example 2-2 Reference
comparative Cracked in cold working example 2-3 Reference
comparative 52 1:1 to 1:3 808 31 Poor example 2-4 Reference
comparative 42 1:1 to 1:5 854 32.2 Poor example 2-5 Reference
comparative 57 1:1 to 1:76 867 30.4 Poor example 2-6 Reference
comparative 45 1:1 to 1:131 958 31.5 Poor example 2-7
[0104] In Table 2-2, Examples 2-26 to 2-37 are working examples, in
which use was made of the same alloying elements as those in
Examples 2-1, 2-6 and 2-16, respectively, each by conducting the
area-reduction working within the range according to the present
invention. Each of those working examples satisfied the
requirements of tensile strength of 500 MPa or greater and
electrical conductivity of 25% IACS or higher. Further, 40% or more
of the sulfide particles in the cross-section in parallel to the
wrought direction were present in the crystals of the matrix, and
the sulfide particles having an aspect ratio of 1:1 to 1:100 were
dispersed in the cross-section in parallel to the wrought
direction, and no cracking occurred in the material working, and
the machinability was also satisfactory.
[0105] Comparative examples 2-10 to 2-12 each had alloy
compositions defined in the present invention, but the working
ratio in the area-reduction working was outside of the range
according to the present invention, and cracking was occurred in
the cold working. Comparative examples 2-13 to 2-16 had the same
alloying elements as in Comparative example 2-5. Comparative
examples 2-13 to 2-15 were subjected to the area-reduction working
to an extent according to the present invention; however, since the
S content was low, although 40% or more of the sulfide particles in
the cross-section in parallel to the wrought direction were present
in the crystals of the matrix, the machinability was poor.
[0106] Comparative example 2-16 was subjected to the area-reduction
working to an extent that was outside of the range according to the
present invention, although 40% or more of the sulfide particles in
the cross-section in parallel to the wrought direction were present
in the crystals of the matrix and no cracking was occurred, sulfide
particles with an aspect ratio exceeding 1:100 were dispersed in
the cross-section in parallel to the wrought direction, and the
machinability was poor.
Example 2-3
[0107] Samples having the alloy compositions of Example 2-6 and
Example 2-16 in Table 2-1, respectively, were evaluated on the
insertion/extraction property of connectors in the same manner as
in Example 1-3. The results are shown in Table 2-3, and it can be
seen that Examples exhibit the insertion/extraction property
equivalent to free cutting beryllium copper of Conventional example
2-2, and that the samples of the working examples are excellent
connector pins. The insertion/extraction property of free cutting
phosphor bronze of Conventional example 2-1 was inferior to
Examples.
TABLE-US-00006 TABLE 2-3 Ratio of insertion/extraction Name force
to initial value Example 2-6 0.86 Example 2-16 0.80 Conventional
example 2-1 0.53 Conventional example 2-2 0.85
[0108] Having described our invention as related to the present
embodiments, it is our intention that the invention not be limited
by any of the details of the description, unless otherwise
specified, but rather be construed broadly within its spirit and
scope as set out in the accompanying claims.
[0109] This non-provisional application claims priority under 35
U.S.C. .sctn.119 (a) on Patent Application No. 2010-280946 filed in
Japan on Dec. 16, 2010, Patent Application No. 2010-210201 filed in
Japan on Sep. 17, 2010, Patent Application No. 2010-143420 filed in
Japan on Jun. 24, 2010, and Patent Application No. 2010-88228 filed
in Japan on Apr. 7, 2010, each of which is entirely herein
incorporated by reference.
REFERENCE SIGNS LIST
[0110] 10 Copper alloy rod [0111] 10' Copper alloy rod cut along
the wrought direction [0112] 10a Cross-section in parallel to the
wrought direction [0113] R Wrought direction [0114] 21 Grain
boundary [0115] 22 Sulfide particle present at a grain boundary
[0116] 23 Sulfide particle present in a grain [0117] 24 Length of a
sulfide particle in the direction perpendicular to the wrought
direction [0118] 25 Length of the sulfide particle in the direction
parallel to the wrought direction [0119] 50, 60 Connector pins
[0120] 51, 61 Slits [0121] 62 Tapering section
* * * * *