U.S. patent application number 13/258467 was filed with the patent office on 2012-02-02 for high-strength copper alloy.
This patent application is currently assigned to San-Etsu Metals Co., Ltd.. Invention is credited to Akimichi Kojima, Katsuyoshi Kondoh, Yoshiharu Kosaka.
Application Number | 20120027638 13/258467 |
Document ID | / |
Family ID | 43011077 |
Filed Date | 2012-02-02 |
United States Patent
Application |
20120027638 |
Kind Code |
A1 |
Kosaka; Yoshiharu ; et
al. |
February 2, 2012 |
HIGH-STRENGTH COPPER ALLOY
Abstract
A high-strength copper alloy contains 20 to 45% of zinc, 0.3 to
1.5% of iron, 0.3 to 1.5% of chromium, and a balance of copper,
based on mass.
Inventors: |
Kosaka; Yoshiharu; (Toyama,
JP) ; Kojima; Akimichi; (Toyama, JP) ; Kondoh;
Katsuyoshi; (Osaka, JP) |
Assignee: |
San-Etsu Metals Co., Ltd.
Toyama
JP
|
Family ID: |
43011077 |
Appl. No.: |
13/258467 |
Filed: |
April 16, 2010 |
PCT Filed: |
April 16, 2010 |
PCT NO: |
PCT/JP2010/056854 |
371 Date: |
September 22, 2011 |
Current U.S.
Class: |
420/471 ;
420/478; 420/479; 420/480; 420/587 |
Current CPC
Class: |
C22C 9/04 20130101; C22F
1/08 20130101 |
Class at
Publication: |
420/471 ;
420/478; 420/587; 420/480; 420/479 |
International
Class: |
C22C 9/04 20060101
C22C009/04; C22C 30/02 20060101 C22C030/02 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 24, 2009 |
JP |
2009-106162 |
Claims
1. A high-strength copper alloy containing 20 to 45% of zinc, 0.3
to 1.5% of iron, 0.3 to 1.5% of chromium, 0.2 to 3.5% of aluminum,
0.3 to 3.5% of calcium, and a balance of copper, based on mass.
2. The high-strength copper alloy according to claim 1, wherein a
content ratio (Fe/Cr) of said iron to said chromium is 0.5 to 2
based on mass.
3. The high-strength copper alloy according to claim 1, wherein
said high-strength copper alloy further contains at least one kind
of element selected from the group consisting of 0.05 to 4% of
lead, 0.02 to 3.5% of bismuth, 0.02 to 0.4% of tellurium, 0.02 to
0.4% of selenium, and 0.02 to 0.15% of antimony, based on mass.
4. The high-strength copper alloy according to claim 1, wherein
said high-strength copper alloy further contains 0.2 to 3% of tin,
based on mass.
5. (canceled)
6. The high-strength copper alloy according to claim 1, wherein
said high-strength copper alloy further contains at least one kind
of element selected from a lanthanoid group consisting of
lanthanum, cerium, neodymium, gadolinium, dysprosium, ytterbium,
and samarium, and a total content of said at least one kind of
element is 0.5 to 5%, based on mass.
7. The high-strength copper alloy according to claim 1, wherein
said high-strength copper alloy further contains at least one kind
of element selected from the group consisting of 0.5 to 3% of
manganese, 0.2 to 1% of silicon, 1.5 to 4% of nickel, 0.1 to 1.2%
of titanium, 0.1 to 1.5% of cobalt, and 0.5 to 2.5% of zirconium,
based on mass.
8. The high-strength copper alloy according to claim 1, wherein
said high-strength copper alloy includes iron-chromium compound
particles at grain boundaries.
9. The high-strength copper alloy according to claim 8, wherein
said iron-chromium compound particles are particles precipitated at
said grain boundaries during solidification in a casting
method.
10. The high-strength copper alloy according to claim 9, wherein
said iron-chromium compound particles have a particle size of 10 to
50 .mu.m.
11. The high-strength copper alloy according to claim 1, wherein
said copper alloy is a copper alloy subjected to hot plastic
working after being produced by a casting method.
12. The high-strength copper alloy according to claim 11, wherein
said hot plastic working is a working method selected from the
group consisting of extrusion, forging, rolling, drawing, and
pulling.
Description
TECHNICAL FIELD
[0001] The present invention relates to high-strength copper alloys
having excellent mechanical characteristics, and more particularly
to high-strength copper alloys produced by a casting method. More
preferably, the present invention is intended to provide
high-strength copper alloys having strength characteristics
improved by performing hot plastic working on cast copper
alloys.
BACKGROUND ART
[0002] Copper alloys are widely used in automotive parts, parts of
home electric appliances, electric, electronic, or optical parts,
piping members (faucet fittings, valves), etc. In view of the
recent measures against global warming, there has been a strong
demand for reduction in size, weight, and thickness of products and
members has been greatly desired, and the copper alloys having
higher specific gravity than iron need to be increased in strength
in order to meet such a demand.
[0003] Of the copper alloys, brass alloys containing zinc are often
used in such parts as described above, due to their corrosion
resistance. Japanese Unexamined Patent Publication No. 2000-119775
(Patent Literature 1) has been proposed as related art for
increasing the strength of the brass alloys. Patent Literature 1
discloses that a brass alloy having tensile strength
characteristics as high as about 600 to 800 MPa is obtained by hot
extrusion of a cast copper alloy. Silicon (Si) as an added element
has an advantage in that it forms .gamma.-phase forming a matrix,
and thus improves a cutting property of a copper alloy. However,
since Si is hard, adding Si causes problems such as higher cutting
resistance and a shorter tool life as compared to brass alloys as
described in JIS H 3250-C3604, C3771, etc.
[0004] Other literatures disclosing high-strength copper alloys
include Japanese Patent No. 3,917,304 (free-cutting copper alloy,
Patent Literature 2) and Japanese Patent No. 3,734,372 (lead-free
free-cutting copper alloy, Patent Literature 3). In the techniques
disclosed in these patent literatures, it is proposed that a small
amount of zirconium and phosphorus be added to obtain granular
crystal rather than dendrite crystal formed by a normal casting
method, and the granular crystal be refined to 10 .mu.m, thereby
implementing high strength and high ductility. However, in the
brass alloys disclosed in these patent literatures, a matrix is
significantly harder than conventional brass alloys, thereby
causing problems such as a degraded cutting property and a shorter
tool life.
[0005] Meanwhile, in Japanese Patent No. 4,190,570 (lead-free
free-cutting copper alloy extruded material, Patent Literature 4),
the inventors succeeded in improving the cutting property of a
brass powder alloy extruded material and also obtaining high
tensile strength thereof by producing brass alloy powder and adding
graphite particles to the brass alloy powder instead of lead by
using a powder metallurgy process. In a manufacturing method of a
copper alloy disclosed in Patent Literature 4, copper alloy powder
having fine crystal grains is produced by using a rapid
solidification method, and this powder is formed and solidified by
hot extrusion, whereby a copper alloy base material having a fine
structure can be obtained. Thus, a copper alloy extruded material
having high strength and high ductility is obtained. However, as
compared to a typical manufacturing process of a brass alloy, the
copper alloy powder need be first formed and solidified in order to
prepare a billet body for extrusion. It is therefore difficult to
apply this manufacturing method to a conventional process of
extruding a cast billet, and a press forming machine, a compacting
apparatus, etc. is required to solidify the copper alloy
powder.
CITATION LIST
Patent Literature
[0006] PTL1: Japanese Unexamined Patent Publication No.
2000-119775
[0007] PTL2: Japanese Patent No. 3,917,304
[0008] PTL3: Japanese Patent No. 3,734,372
[0009] PTL4: Japanese Patent No. 4,190,570
SUMMARY OF INVENTION
Technical Problem
[0010] It is an object of the present invention to manufacture a
copper alloy having high strength characteristics by a casting
process. In order to achieve this object, the present invention
proposes a copper-zinc alloy containing a proper amount of iron and
chromium. Thus, the high-strength copper alloy according to the
present invention is widely applicable to automotive parts, parts
of home electric appliances, electric, electronic, or optical
parts, piping members, etc.
Solution to Problem
[0011] A high-strength copper alloy according to the present
invention contains 20 to 45% of zinc, 0.3 to 1.5% of iron, 0.3 to
1.5% of chromium, and a balance of copper, based on mass.
[0012] Preferably, in the high-strength copper alloy, a content
ratio (Fe/Cr) of the iron to the chromium is 0.5 to 2 based on
mass.
[0013] In one embodiment, the high-strength copper alloy further
contains at least one kind of element selected from the group
consisting of 0.05 to 4% of lead, 0.02 to 3.5% of bismuth, 0.02 to
0.4% of tellurium, 0.02 to 0.4% of selenium, and 0.02 to 0.15% of
antimony, based on mass. The high-strength copper alloy may further
contain 0.2 to 3% of tin, based on mass. The high-strength copper
alloy may further contain 0.2 to 3.5% of aluminum and 0.3 to 3.5%
of calcium, based on mass. The high-strength copper alloy may
further contain at least one kind of element selected from a
lanthanoid group consisting of lanthanum, cerium, neodymium,
gadolinium, dysprosium, ytterbium, and samarium, and a total
content of the at least one kind of element may be 0.5 to 5%, based
on mass. The high-strength copper alloy may further contain at
least one kind of element selected from the group consisting of 0.5
to 3% of manganese, 0.2 to 1% of silicon, 1.5 to 4% of nickel, 0.1
to 1.2% of titanium, 0.1 to 1.5% of cobalt, and 0.5 to 2.5% of
zirconium, based on mass.
[0014] Preferably, the high-strength copper alloy includes
iron-chromium compound particles at grain boundaries. The
iron-chromium compound particles are particles precipitated at the
grain boundaries during solidification in a casting method, and
preferably have a particle size of 10 to 50 .mu.m.
[0015] Preferably, the copper alloy is a copper alloy subjected to
hot plastic working after being produced by a casting method. The
hot plastic working is, e.g., a working method selected from the
group consisting of extrusion, forging, rolling, drawing, and
pulling.
[0016] The configurations, functions, advantageous effects, etc. of
the present invention described above will be described below in
"Description of Embodiments."
BRIEF DESCRIPTION OF DRAWINGS
[0017] FIG. 1 is a stress-strain diagram in a tension test.
[0018] FIG. 2 shows images showing a result of structure
observation by an optical microscope.
[0019] FIG. 3 shows an image showing a result of SEM-EDS analysis
of a brass alloy extruded material.
[0020] FIG. 4 is a diagram illustrating a hole drilling test
method.
DESCRIPTION OF EMBODIMENTS
[0021] [Addition of Iron and Chromium]
[0022] In a copper alloy of the present invention, iron and
chromium are essential elements to be added. The iron content is
0.3 to 1.5%, and the chromium content is 0.3 to 1.5%, based on
mass. Since chromium has low solid solubility in copper, a
copper-chromium mother alloy is prepared, and is added to molten
pure copper melted in a crucible, thereby adjusting the chromium
content. Next, a predetermined weight of iron is added. Then, other
element or elements are added as required, and lastly, zinc is
added. The mixture is stirred and poured into a casting mold. Zinc
tends to evaporate as compared to other elements due to its high
vapor pressure. Thus, zinc is lastly added to the molten copper
alloy.
[0023] The molten copper alloy is cooled and solidified in the
casting mold. During the cooling and solidification, chromium
slightly solid-solved in copper is crystallized at copper grain
boundaries, and then iron is crystallized near the crystallized
chromium. Thus, chromium-iron compound particles having a size
(particle size) of about 10 to 50 .mu.m are present at the grain
boundaries, and strength of the brass alloy is increased due to
dispersion strengthening by the compound particles at the grain
boundaries.
[0024] In Japanese Patent No. 4,190,570 (lead-free free-cutting
copper alloy extruded material) as well, the inventors describe the
effect of improving strength of the brass alloy by adding iron and
chromium. However, the invention described in this patent is based
on a powder metallurgy process by a rapid solidification method as
a basic manufacturing method, chromium and iron, supersaturatedly
solid-solved in copper alloy powder, are precipitated during an
extrusion process, and are precipitated at grain boundaries or
inside crystal grains as an iron-chromium compound as small as
several hundreds of nanometers to several microns. Such submicron
fine iron-chromium compound particles that are precipitated based
on the powder metallurgy process are completely different in a
grain size and a production mechanism from the iron-chromium
particles (compound particles) crystallized at the grain boundaries
during solidification by a casting method as proposed in the
present invention.
[0025] Regarding the iron content and the chromium content that are
suitable for strengthening the brass alloy, it is desirable that
the brass alloy contain 0.3 to 1.5% of iron and 0.3 to 1.5% of
chromium, based on mass. The effect of improving the strength of
the brass alloy as described above is not sufficient if the iron
content and the chromium content are less than 0.3%. On the other
hand, ductility of the brass alloy is reduced if the iron content
and the chromium content are more than 1.5%. Corrosion resistance
of the brass alloy is reduced if the iron content is more than
2%.
[0026] It is desirable that the content ratio (Fe/Cr) of iron to
chromium be 0.5 to 2, based on mass. The proportion of the
chromium-iron compound at the grain boundaries described above
increases in the case where the content ratio of iron to chromium
is in this range. In other words, if the content ratio of iron to
chromium is less than 0.5 or more than 2, iron or chromium is
independently crystallized at the grain boundaries, whereby the
effect of improving the strength is reduced.
[0027] [Addition of Element for Improving Cutting Property]
[0028] In order to improve the cutting property of the brass alloy,
it is desirable that the brass alloy contains at least one kind of
element selected from the group consisting of 0.05 to 4% of lead,
0.02 to 3.5% of bismuth, 0.02 to 0.4% of tellurium, 0.02 to 0.4% of
selenium, and 0.02 to 0.15% of antimony, based on mass. If the
content of each element is less than the lower limit of the above
range, a sufficient cutting property cannot be obtained, and a
brass alloy base material has a rough surface after a cutting
process, and the tool life is reduced. On the other hand, if the
content of each element is more than the upper limit of the above
range, mechanical characteristics such as strength and ductility
are degraded because the element serves as an origin of fracture.
Note that in view of the recent environmental problems, since the
use of lead is restricted, it is more preferable to select bismuth
as an element for improving the cutting property.
[0029] [Various Added Elements]
[0030] Tin is effective not only in forming .gamma.-phase in the
matrix, but also in increasing the strength of the alloy by forming
a compound with copper. A preferred tin content is 0.2 to 3% based
on mass. The effect described above is not sufficient if the tin
content is less than 0.2%. On the other hand, adding more than 3%
of tin reduces the ductility of the brass alloy. Adding more than
2% (the content) of tin improves dezincing resistance of
.beta.-phase.
[0031] Aluminum forms an intermetallic compound with copper, and
its spherical particles are dispersed in the matrix, thereby
improving mechanical characteristics such as strength and hardness,
and high-temperature oxidation resistance of the copper alloy. A
preferred aluminum content is 0.2 to 3.5% based on mass. The above
effect of aluminum is not sufficient if the aluminum content is
less than 0.2%. On the other hand, adding more than 3.5% of
aluminum coarsens the compound with copper, resulting in reduced
ductility of the brass alloy. Moreover, since aluminum, together
with calcium described below, forms an intermetallic compound
Al.sub.2Ca, thereby contributing to improvement in strength and
hardness.
[0032] Calcium, contained together with aluminum in the copper
alloy, forms the intermetallic compound Al.sub.2Ca, thereby
contributing to improvement in strength and hardness. A preferred
calcium content is 0.3 to 3.5% based on mass. The above effect is
not sufficient if the calcium content is less than 0.3%. On the
other hand, adding more than 3.5% of calcium coarsens the
intermetallic compound Al.sub.2Ca, resulting in reduced ductility
of the brass alloy.
[0033] A lanthanoid group (lanthanum, cerium, neodymium,
gadolinium, dysprosium, ytterbium, and samarium) is effective as
each element of the lanthanoid group is precipitated at grain
boundaries as a compound with copper or is independently
crystallized at the grain boundaries, and thus strengthens the
matrix. It is desirable that the total content of the lanthanoid
element group be 0.5 to 5% based on mass. The effect of the
lanthanoid element group is not sufficient if the total content
thereof is less than 0.5%. Adding more than 5% of the lanthanoid
element group reduces the ductility, and also excessively hardens
the copper alloy, thereby reducing extrusion workability.
[0034] The strength and hardness of the copper alloy can be
improved by adding at least one kind of element selected from the
group consisting of 0.5 to 3% of manganese, 0.2 to 1% of silicon,
1.5 to 4% of nickel, 0.1 to 1.2% of titanium, 0.1 to 1.5% of
cobalt, and 0.5 to 2.5% of zirconium as a transition metal element
group, based on mass. The above effect of improving the
characteristics is not sufficient if the content of each element is
less than the lower limit of the above range. On the other hand,
the ductility of the copper alloy is reduced if the content of each
element exceeds the upper limit of the above range.
[0035] [Manufacturing Method]
[0036] A molten copper alloy having the above composition is
produced, and an ingot material is produced by a method in which
the molten copper alloy is poured into a casting mold, or a
continuous casting method. Moreover, hot plastic working, such as
an extrusion, forging, rolling, drawing, or pulling, is performed
on the ingot material as necessary. At this time, the heating
temperature that allows the ingot to be sufficiently
plastic-deformed is in the range of 600 to 850.degree. C. In
particular, the heating temperature is desirably 750.degree. C. or
less in order to suppress evaporation of zinc during heating.
EXAMPLES
(1) Example 1
[0037] Cast copper alloy ingots containing elements shown in Tables
1 and 2 were prepared. Each ingot was subjected to a hot extrusion
process immediately after heating and keeping the ingot at
700.degree. C. The extrusion process was performed at an extrusion
ratio of 37. Tensile test pieces were obtained from each copper
alloy extruded material, and a tensile test was conducted at room
temperature at a strain rate of 5.times.10.sup.-4/s. The result is
shown in Tables 1 and 2. Sample Nos. 1 to 16 are examples of the
present invention, and Sample Nos. 17 to 19 are comparative
examples.
[0038] [Table 1]
[0039] [Table 2]
[0040] Since Sample Nos. 1 to 5 as examples of the present
invention contain a predetermined amount of iron and chromium,
tensile strength (TS) of the extruded material is higher than
Sample No. 19 as a comparative example by about 130 to 210 MPa.
This is because iron-chromium compound particles made of iron and
chromium are dispersed at grain boundaries, and thus the strength
of the copper alloy is significantly increased. It is also
recognized that the tensile strength is increased as the amount of
iron and chromium is increased.
[0041] Sample Nos. 6 to 8 as examples of the present invention are
copper alloys containing bismuth (Bi), and Sample Nos. 9 to 11 as
examples of the present invention are copper alloys containing lead
(Pb). Bismuth and lead are the elements that are added to improve
the cutting property of the copper alloy. The tensile strength of
the copper alloys of Sample Nos. 9 to 11 is slightly lower than
Sample No. 2 as an example of the present invention containing
neither bismuth nor lead, but is higher than Sample No. 17 or 18 as
a comparative example by about 160 to 190 MPa. Thus, adding bismuth
or lead to the brass alloy containing iron and chromium can improve
the cutting property while maintaining high tensile strength.
[0042] In Sample Nos. 12 and 13 as examples of the present
invention, it can be verified that the strength is increased by
adding tin (Sn).
[0043] Sample Nos. 14 to 16 as examples of the present invention
contain aluminum (Al) and calcium (Ca). Thus, the tensile strength
is significantly increased by dispersion of an intermetallic
compound Al.sub.2Ca in the matrix of the copper alloy.
(2) Example 2
[0044] As in Example 1, cast copper alloy ingots containing
elements shown in Tables 3 and 4 were prepared. Each ingot was
subjected to a hot extrusion process immediately after heating and
keeping the ingot at 700.degree. C. The extrusion process was
performed at an extrusion ratio of 37. Tensile test pieces were
obtained from each copper alloy extruded material, and a tensile
test was conducted at room temperature at a strain rate of
5.times.10.sup.-4/s. The result is shown in Tables 3 and 4. Sample
Nos. 20 to 24 and 28 to 33 are examples of the present invention,
and Sample Nos. 25 to 27, 34, and 35 are comparative examples.
[0045] [Table 3]
[0046] [Table 4]
[0047] Each of Sample Nos. 21, 22, 23, and 24 as examples of the
present invention contains a lanthanoid element. Thus, the tensile
strength of these samples reaches 640 to 680 MPa, which is higher
than Sample No. 20 as an example of the present invention
containing no lanthanoid element.
[0048] Each of Sample Nos. 29 and 30 as examples of the present
invention is also a brass alloy containing a lanthanoid element. It
can be verified that the tensile strength of these samples is
significantly higher than Sample No. 28 as an example of the
present invention containing no lanthanoid element.
[0049] Sample No. 31 as an example of the present invention is a
brass alloy containing a proper amount of silicon (Si), Sample No.
32 as an example of the present invention is a brass alloy
containing a proper amount of nickel (Ni), and Sample No. 33 as an
example of the present invention is a brass alloy containing a
proper amount of titanium (Ti). It can be verified that the tensile
strength of these samples is higher than Sample No. 28 as an
example of the present invention containing none of these
elements.
[0050] Although Sample Nos. 25 to 27, 34, and 35 as comparative
examples contain iron and chromium, the content ratio of iron to
chromium is not in the range of 0.5 to 2, based on mass. Thus, it
is recognized that the tensile strength of these samples is higher
than Sample No. 19 as a comparative example containing neither iron
nor chromium. However, the tensile strength of these elements is
lower than the brass alloys as examples of the present invention
whose content ratio of iron to chromium is in the range of 0.5 to 2
(Sample Nos. 1 to 5 as examples of the present invention in Table
1, Sample No. 20 as an example of the present invention in Table 3,
and Sample No. 28 as an example of the present invention in Table
4).
(3) Example 3
[0051] Tensile test pieces were obtained from the brass alloy
extruded materials of Sample Nos. 3 and 5 as examples of the
present invention and the brass extruded material of Sample No. 19
as a comparative example, and a tensile test was conducted. FIG. 1
shows a stress-strain diagram in this tensile test. It can be seen
from the figure that Sample Nos. 3 and 5 as examples of the present
invention have higher tensile strength and higher endurance
strength (yield strength) than Sample No. 19 as a comparative
example.
(4) Example 4
[0052] FIG. 2 shows the result of structure observation of Sample
No. 3 as an example of the present invention by an optical
microscope. It can be seen from the figure that Fe--Cr compound
particles having a particle size of about 20 to 50 .mu.m are
uniformly dispersed in the brass alloy matrix.
(5) Example 5
[0053] FIG. 3 shows the result of scanning electron
microscopy-energy dispersive spectroscopy (SEM-EDS) analysis of the
brass alloy extruded material of Sample No. 12 as an example of the
present invention described in Example 1. It can be seen from the
figure that main components of the compound that is dispersed are
iron (Fe) and chromium (Cr).
(6) Example 6
[0054] Cast copper alloy ingots containing elements shown in Tables
5 and 6 are prepared. Tensile test pieces were obtained from each
copper alloy ingot, and a tensile test was conducted at room
temperature at a strain rate of 5.times.10.sup.-4/s. The result is
shown in Tables 5 and 6. Sample Nos. 1 to 16 are examples of the
present invention, and Sample Nos. 17 to 19 are comparative
examples. It can be seen that the strength of the examples of the
present invention is higher than the comparative examples even in
the cast ingot materials before the protrusion process, because the
examples of the present invention contains a proper amount of
predetermined elements.
[0055] [Table 5]
[0056] [Table 6]
(7) Example 7
[0057] The cutting property of the brass alloy extruded materials
of Sample Nos. 5 to 11 as examples of the present invention and
Sample Nos. 17 to 19 as comparative examples described in Examples
1 and 2 were evaluated by conducting a drilling test. Note that as
a test method, the time it takes to drill a hole having a depth of
5 mm in each copper alloy extruded material with constant load (in
this example, with a weight of 1 kg) applied to a drill as shown in
FIG. 4 was compared. Shorter processing time means a more
satisfactory cutting property. Note that the drilling test was
conducted for 10 samples per extruded material by rotating a
high-speed steel drill having a diameter of 4.8 mm.phi. at a
rotational speed of 1,000 rpm under dry conditions (with no cutting
oil), and a mean value was obtained from the measurement values.
The result is shown in Table 7.
[0058] [Table 7]
[0059] As shown in Table 7, in Sample No. 5 as an example of the
present invention containing none of the elements that improve the
cutting property such as bismuth and lead, a hole having a depth of
5 mm was not able to be formed under the above conditions even if
the drilling was performed for three minutes. Sample Nos. 6 to 8 as
examples of the present invention are brass alloys containing
bismuth. In Sample Nos. 6 to 8, a hole was able to be formed, and
the processing time decreases as the amount of bismuth is
increased. Sample Nos. 9 to 11 as examples of the present invention
are alloys containing lead, and the cutting time decreases as the
lead content is increased. Thus, it was verified that adding
bismuth or lead can significantly improve the cutting property
while maintaining high tensile strength.
(8) Example 8
[0060] Cast copper alloy ingots containing elements shown in Table
8 were prepared. Each ingot was subjected to a hot extrusion
process immediately after heating and keeping the ingot at
650.degree. C. The extrusion process was performed at an extrusion
ratio of 37. Tensile test pieces were obtained from each copper
alloy extruded material, and a tensile test was conducted at room
temperature at a strain rate of 5.times.10.sup.-4/s. Regarding
evaluation of the cutting property, mean processing time was
calculated by a method similar to that of Example 7 described
above. The result is shown in Table 8. All of Sample Nos. 40 to 56
are examples of the present invention.
[0061] [Table 8]
[0062] As can be seen from Table 8, copper alloys having high
tensile strength, high elongation (ductility), and a high cutting
property can be obtained by adding to brass a proper amount of
element that improves the strength and a proper amount of element
that improves the cutting property.
(9) Example 9
[0063] Molten copper alloys containing elements shown in Table 9
were prepared, and powders having a powder particle size of 150
.mu.m or less (a mean particle size of 112 to 138 .mu.m) were
produced by a water atomizing method. Each powder was heated and
pressed (with a pressure of 40 MPa) in a vacuum atmosphere at
750.degree. C. by a discharge plasma sintering apparatus to produce
a dense sintered compact. Each sintered compact was subjected to a
hot extrusion process immediately after heating and keeping (for 15
minutes) the sintered compact at 650.degree. C. in a nitrogen gas
atmosphere. The extrusion process was performed at an extrusion
ratio of 37. Tensile test pieces were obtained from each copper
alloy extruded material, and a tensile test was conducted at room
temperature at a strain rate of 5.times.10.sup.-4/s. Regarding
evaluation of the cutting property, mean processing time was
calculated by a method similar to that of Example 7 described
above. The result is shown in Table 9. All of Sample Nos. 60 to 69
are examples of the present invention.
[0064] [Table 9]
[0065] As can be seen from Table 9, copper alloys having high
tensile strength, high elongation (ductility), and a high cutting
property can be obtained by adding to brass a proper amount of
element that improves the strength and a proper amount of element
that improves the cutting property. In particular, in the case of
using powder produced by the water atomizing method, a grain
refining effect is additionally provided, and thus the tensile
strength of the extruded material is further increased as compared
to the case of producing the extrusion ingot by the casting
method.
INDUSTRIAL APPLICABILITY
[0066] The present invention can be advantageously used as a
high-strength copper alloy having excellent mechanical
characteristics.
TABLE-US-00001 TABLE 1 Sample No. 1 2 3 4 5 6 7 8 9 10 11 Zn 39.8
40.2 40.4 39.9 40.0 40.1 39.8 40.0 39.8 40.1 39.9 Fe 0.42 0.63 0.98
1.23 1.41 0.68 0.73 0.70 1.05 1.09 1.06 Cr 0.38 0.58 1.02 1.17 1.38
0.73 0.90 0.97 0.98 1.12 1.19 Sn 0.02 -- 0.03 -- 0.02 0.04 -- --
0.01 -- 0.02 Bi -- -- -- -- -- 0.57 1.26 2.28 -- -- -- Pb 0.03 0.02
0.01 0.02 0.03 0.02 0.01 0.02 0.45 0.92 2.08 Al -- -- -- -- -- --
-- -- -- -- -- Ca -- -- -- -- -- -- -- -- -- -- -- Cu Balance
Balance Balance Balance Balance Balance Balance Balance Balance
Balance Balance Fe/Cr Ratio 1.11 1.09 0.96 1.05 1.02 0.93 0.81 0.72
1.07 0.97 0.89 TS 587 609 624 647 665 598 589 580 609 600 587
.epsilon. 30.2 29.1 27.9 26.4 25.2 31.2 29.3 27.8 28.7 27.4 26.1
TS; Tensile Strength (MPa), .epsilon.; Breaking Elongation (%)
TABLE-US-00002 TABLE 2 Sample No. 12 13 14 15 16 17 18 19 Zn 40.2
40.7 39.7 39.4 39.2 40.1 39.8 40.4 Fe 0.72 0.69 0.82 0.99 0.87 0.02
0.03 0.01 Cr 0.97 0.87 0.98 1.19 1.03 -- -- -- Sn 0.98 2.13 -- --
-- -- -- -- Bi -- -- -- -- -- 2.27 -- -- Pb 0.01 0.02 0.02 0.03
0.02 0.02 2.78 0.02 Al -- -- 0.43 0.64 0.88 -- -- -- Ca -- -- 0.37
0.55 0.69 -- -- -- Cu Balance Balance Balance Balance Balance
Balance Balance Balance Fe/Cr Ratio 0.74 0.79 0.84 0.83 0.84 -- --
-- TS 644 662 644 658 668 402 411 453 .epsilon. 26.3 25.1 26.2 25.3
24.4 39.8 38.7 48.9 TS; Tensile Strength (MPa), .epsilon.; Breaking
Elongation (%)
TABLE-US-00003 TABLE 3 Sample No. 20 21 22 23 24 25 26 27 Zn 40.1
40.4 39.8 39.3 40.2 40.2 40.0 40.3 Fe 0.97 0.89 0.88 0.93 0.90 0.84
0.86 0.92 Cr 0.89 0.83 0.88 0.86 0.83 0.23 0.31 0.33 Sn 0.01 0.02
0.03 0.02 0.03 0.03 0.01 0.02 Pb 0.03 0.02 0.01 0.02 0.03 0.02 0.01
0.02 La -- 1.09 2.54 -- -- -- -- -- Ce -- -- -- 0.78 -- -- -- -- Nd
-- -- -- -- 0.65 -- -- -- Gd -- -- -- -- -- -- -- -- Yb -- -- -- --
-- -- -- -- Si -- -- -- -- -- -- -- -- Ni -- -- -- -- -- -- -- --
Ti -- -- -- -- -- -- -- -- Cu Balance Balance Balance Balance
Balance Balance Balance Balance Fe/Cr Ratio 1.09 1.07 1.00 1.08
1.08 3.65 2.77 2.79 TS 618 641 683 662 652 554 563 567 .epsilon.
28.2 25.7 21.2 23.3 24.8 33.6 32.1 32.6
TABLE-US-00004 TABLE 4 Sample No. 28 29 30 31 32 33 34 35 Zn 39.4
40.3 39.6 40.1 40.4 39.5 39.3 40.4 Fe 0.62 0.58 0.59 0.62 0.60 0.64
0.57 0.60 Cr 0.60 0.59 0.62 0.61 0.62 0.65 0.21 0.17 Sn 0.01 --
0.02 0.02 0.03 -- 0.02 -- Pb 0.45 0.92 2.08 0.01 0.02 0.02 0.03
0.02 La -- -- -- -- -- -- -- -- Ce -- -- -- -- -- -- -- -- Nd -- --
-- -- -- -- -- -- Gd -- 1.65 -- -- -- -- -- -- Yb -- -- 1.32 -- --
-- -- -- Si -- -- -- 0.38 -- -- -- -- Ni -- -- -- -- 1.87 -- -- --
Ti -- -- -- -- -- 0.44 -- -- Cu Balance Balance Balance Balance
Balance Balance Balance Balance Fe/Cr Ratio 1.03 0.98 0.95 1.02
0.97 0.98 2.71 3.53 TS 601 653 646 634 639 633 549 555 .epsilon.
29.6 25.3 26.1 26.2 27.4 28.1 34.4 34.1
TABLE-US-00005 TABLE 5 Sample No. 1 2 3 4 5 6 7 8 9 10 11 Zn 39.8
40.2 40.4 39.9 40.0 40.1 39.8 40.0 39.8 40.1 39.9 Fe 0.42 0.63 0.98
1.23 1.41 0.68 0.73 0.70 1.05 1.09 1.06 Cr 0.38 0.58 1.02 1.17 1.38
0.73 0.90 0.97 0.98 1.12 1.19 Sn 0.02 -- 0.03 -- 0.02 0.04 -- --
0.01 -- 0.02 Bi -- -- -- -- -- 0.57 1.26 2.28 -- -- -- Pb 0.03 0.02
0.01 0.02 0.03 0.02 0.01 0.02 0.45 0.92 2.08 Al -- -- -- -- -- --
-- -- -- -- -- Ca -- -- -- -- -- -- -- -- -- -- -- Cu Balance
Balance Balance Balance Balance Balance Balance Balance Balance
Balance Balance Fe/Cr Ratio 1.11 1.09 0.96 1.05 1.02 0.93 0.81 0.72
1.07 0.97 0.89 TS 442 449 464 477 482 437 441 422 449 452 426
.epsilon. 36.2 32.3 29.7 28.9 28.1 33.7 32.1 29.8 30.3 30.1 29.4
TS; Tensile Strength (MPa), .epsilon.; Breaking Elongation (%)
TABLE-US-00006 TABLE 6 Sample No. 12 13 14 15 16 17 18 19 Zn 40.2
40.7 39.7 39.4 39.2 40.1 39.8 40.4 Fe 0.72 0.69 0.82 0.99 0.87 0.02
0.03 0.01 Cr 0.97 0.87 0.98 1.19 1.03 -- -- -- Sn 0.98 2.13 -- --
-- -- -- -- Bi -- -- -- -- -- 2.27 -- -- Pb 0.01 0.02 0.02 0.03
0.02 0.02 2.78 0.02 Al -- -- 0.43 0.64 0.88 -- -- -- Ca -- -- 0.37
0.55 0.69 -- -- -- Cu Balance Balance Balance Balance Balance
Balance Balance Balance Fe/Cr Ratio 0.74 0.79 0.84 0.83 0.84 -- --
-- TS 473 481 467 482 485 301 308 332 .epsilon. 28.9 27.9 28.5 27.5
26.2 42.5 44.2 51.4 TS; Tensile Strength (MPa), .epsilon.; Breaking
Elongation (%)
TABLE-US-00007 TABLE 7 Sample No. 5 6 7 8 9 10 11 17 18 19 Mean
Cutting Time Unable to Cut 36.85 29.94 24.24 36.61 28.62 21.79 22.6
18.83 45.26 n = 1 >180 38.7 31.1 24.4 33.2 29.2 21.2 22.4 19.2
38.2 n = 2 >180 34.5 29.8 24.6 36.4 28.4 22.3 23.1 18.7 39.2 n =
3 >180 36.6 30.2 24.3 38.3 28.1 21.8 23.7 18.3 40.2 n = 4
>180 35.7 30.8 23.3 37.2 29.6 21.7 22.2 18.9 41.0 n = 5 >180
37.2 28.8 24.1 34.3 28.4 21.5 22.6 19.0 42.0 n = 6 >180 36.8
29.7 24.7 37.9 29.4 21.9 22.8 19.1 43.4 n = 7 >180 36.6 29.2
25.1 38.2 28.3 22.1 22.3 18.7 46.6 n = 8 >180 37.5 28.6 23.8
36.8 27.9 22.3 21.8 18.6 48.4 n = 9 >180 37.7 30.4 23.9 37.6
28.8 21.7 22.5 19.1 54.4 n = 10 >180 37.2 30.8 24.2 36.2 28.1
21.4 22.6 18.7 59.2 Drilling Load: 1 kgf, Drill Diameter; 5 mm
.phi., Hole Depth; 5 mm
TABLE-US-00008 TABLE 8 Tensile Endurance Mean Sample Added Element
(wt %) Strength Stress Breaking Cutting No. Zn Fe Cr Sn Ti Bi Pb
Fe/Cr MPa MPa Elongation % Time s 40 40.57 0.54 0.70 0.65 2.37 0.77
610.2 311.6 31.3 33.21 41 40.81 0.23 0.26 0.60 0.99 0.89 596.7
290.7 29.4 36.12 42 40.64 0.23 0.26 0.60 2.02 0.88 595.8 293.4 27.4
14.77 43 40.83 0.22 0.22 0.58 2.85 1.00 622.4 284.1 22.2 18.10 44
40.30 0.61 0.88 0.66 1.90 0.69 606.2 298.2 28.1 28.06 45 39.22 0.47
0.45 0.62 1.89 1.04 523.1 302.3 32.2 27.45 46 39.26 0.40 0.58 0.62
2.12 0.69 506.5 282.9 29.4 31.50 47 37.30 0.68 0.83 0.79 2.55 0.82
547.2 339.9 16.4 29.18 48 37.30 0.68 0.83 0.79 2.98 0.82 600.1
348.9 28.8 43.04 49 39.65 0.65 0.98 0.63 1.51 0.66 629.7 294.8 29.3
25.13 50 40.50 0.63 0.98 0.65 2.19 0.64 624.4 334.8 31.8 33.08 51
40.31 0.51 0.73 0.66 2.45 0.70 600.8 291.0 34.8 26.89 52 40.44 0.33
0.49 0.64 2.28 0.67 613.7 322.9 33.6 35.73 53 40.86 0.22 0.34 0.59
2.97 0.65 582.1 284.8 36.8 22.37 54 40.03 0.43 0.54 0.98 2.03 0.80
629.7 294.8 28.5 35.08 55 39.81 0.38 0.67 0.65 0.99 2.95 0.57 604.6
222.3 34.4 29.52 56 39.43 0.31 0.37 0.64 0.89 3.24 0.84 550.4 245.0
36.8 20.82
TABLE-US-00009 TABLE 9 Tensile Endurance Mean Sample Added Element
(wt %) Strength Stress Breaking Cutting No. Zn Fe Cr Sn Ti Bi Pb
Fe/Cr MPa MPa Elongation % Time s 60 40.57 0.54 0.70 0.65 1.01 1.23
0.77 605.6 379.9 16.2 33.45 61 40.30 0.61 0.88 0.66 1.90 1.32 0.69
586.5 363.4 12.9 32.05 62 40.30 0.61 0.88 0.66 1.90 1.28 0.69 586.6
378.4 9.7 36.07 63 40.50 0.63 0.98 0.65 2.98 0.64 626.7 364.4 25.2
24.56 64 40.50 0.63 0.98 0.65 2.65 0.64 646.2 393.2 19.1 29.61 65
40.31 0.51 0.73 0.66 3.13 0.70 604.1 365.0 23.6 22.17 66 40.86 0.22
0.34 0.59 3.53 0.65 580.0 332.0 33.6 19.25 67 40.03 0.43 0.54 0.98
2.45 0.80 626.4 324.4 25.7 28.29 68 40.03 0.43 0.54 0.98 2.34 0.80
646.2 389.9 19.1 31.87 69 39.81 0.30 0.56 0.65 0.99 2.54 0.54 654.3
457.1 19.3 27.25
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