U.S. patent application number 15/562684 was filed with the patent office on 2018-03-29 for copper alloy for use in a member for water works.
The applicant listed for this patent is KURIMOTO, LTD.. Invention is credited to Syohei MATSUBA, Takeaki MIYAMOTO, Hiroshi YAMADA, Masaaki YAMAMOTO.
Application Number | 20180087130 15/562684 |
Document ID | / |
Family ID | 57003999 |
Filed Date | 2018-03-29 |
United States Patent
Application |
20180087130 |
Kind Code |
A1 |
MIYAMOTO; Takeaki ; et
al. |
March 29, 2018 |
COPPER ALLOY FOR USE IN A MEMBER FOR WATER WORKS
Abstract
It is an object of the present invention to obtain a copper
alloy for use in a member for water works which inhibits leaching
of Pb and exhibits suitable mechanical properties and castability,
while restraining the amount of usage of Bi but securing the
recyclability. The alloy of the present invention contains 0.5% by
mass or less of Ni; 12% by mass or more and 21% by mass or less of
Zn; 1.5% by mass or more and 4.5% by mass or less of Sn, a total
content of Zn and Sn being 23.5% by mass or less; 0.005% by mass or
more and 0.15% by mass or less of P; 0.05% by mass or more and
0.30% by mass or less of Pb; less than 0.2% by mass of Bi; and the
balance, wherein the balance is Cu and unavoidable impurities.
Inventors: |
MIYAMOTO; Takeaki; (Osaka,
JP) ; YAMAMOTO; Masaaki; (Osaka, JP) ;
MATSUBA; Syohei; (Osaka, JP) ; YAMADA; Hiroshi;
(Osaka, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KURIMOTO, LTD. |
Osaka |
|
JP |
|
|
Family ID: |
57003999 |
Appl. No.: |
15/562684 |
Filed: |
March 31, 2015 |
PCT Filed: |
March 31, 2015 |
PCT NO: |
PCT/JP2015/060141 |
371 Date: |
September 28, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C22C 9/04 20130101 |
International
Class: |
C22C 9/04 20060101
C22C009/04 |
Claims
1. A copper alloy for use in a member for water works, the copper
alloy consisting of: 0.5% by mass or less of Ni; 12% by mass or
more and 21% by mass or less of Zn; 1.4% by mass or more and 4.5%
by mass or less of Sn, a total content of Zn and Sn being 23.5% by
mass or less; 0.005% by mass or more and 0.15% by mass or less of
P; 0.05% by mass or more and 0.30% by mass or less of Pb; less than
0.2% by mass of Bi; and the balance, wherein the balance is Cu and
unavoidable impurities.
Description
TECHNICAL FIELD
[0001] The present invention relates to a material for use in a
member for water works, which is made of a copper alloy and in
which the level of lead leaching is not more than a stipulated
value.
BACKGROUND ART
[0002] A cast bronze metal (JIS H5120 CAC406), which has been
conventionally used for parts in materials and equipment for water
works and in feed water supply systems, is excellent in
castability, corrosion resistance, machinability, and/or water
pressure resistance and used for parts in materials and equipment
for water works and in feed water supply systems, and the like in
various fields. This cast bronze metal (CAC406) contains from 4.0
to 6.0% by weight of lead so as to have the high machinability, and
has characteristics of easy workability. However, this lead
contained has a property to leach into the tap water in contact
with the same, which fails to satisfy recent leaching lead amount
regulations. Thus, in order to reduce the amount of toxic lead
leaching, a copper alloy containing a reduced content of lead, or a
lead-free copper alloy which contains no lead have been
examined.
[0003] For example, Patent Document 1 as mentioned below discloses
a brass alloy having an adjusted composition containing from 8 to
40% by mass of Zn, 0.0005 to 0.04% by mass of Zr, 0.01 to 0.25% by
mass of P, at least one or more kinds of 0.005 to 0.45% by mass of
Pb, 0.005 to 0.45% by mass of Bi, 0.03 to 0.45% by mass of Se, and
0.01 to 0.45% by mass of Te, and the balance of Cu and unavoidable
impurities. This brass alloy is an alloy in which solid metals and
liquid metals mixed in a semi-solid state are solidified, and in
the course of its solidification, granular .alpha. primary crystals
are crystallized or an .alpha. solid phase exists. Further, it is
disclosed that as conditions of other elements, one or more kinds
of 2 to 5% by mass of Si, 0.05 to 6% by mass of Sn, and 0.05 to
3.5% by mass of Al may be contained and in particular, Zr with the
coexistence with P is effective in the size reduction in a
semi-solid state.
[0004] Moreover, Patent Document 2 as mentioned below discloses a
copper alloy for use in a member for water works, the copper alloy
containing: less than 0.5% by mass of Ni in a limited manner; less
than the detection limit of Pb; 0.2% by mass or more and 0.9% by
mass or less of Bi; 12.0% by mass or more and 20.0% by mass or less
of Zn; 1.5% by mass or more and 4.5% by mass or less of Sn; and
0.005% by mass or more and 0.1% by mass or less of P; in which a
total content of Zn and Sn is 21.5% by mass or less, and the
balance being unavoidable impurities and Cu. Further, it is
proposed that 0.0003 to 0.006% by mass of B is additionally
contained.
PRIOR ART DOCUMENT
Patent Document
[0005] Patent Document 1: Japanese Patent No. 5116976
[0006] Patent Document 2: Japanese Patent No. 5406405
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0007] Conventionally, as copper alloys containing reduced toxic
Pb, a copper alloy containing Bi and Si substituting Pb has been
used to prevent a reduction in properties, such as the
machinability and the water pressure resistance. On the other hand,
in machine components unrelated to lead leaching other than members
for water works, and the like, a cast bronze metal containing lead
is often used. In cases in which such copper alloys are produced on
the same line, if a cast bronze metal containing lead is melted and
cast after a lead-free copper alloy containing Bi and Si, Bi and Si
of the lead-free copper alloy produced before remain in a melting
furnace and are mixed into a cast bronze metal to be produced. In a
cast bronze metal product into which these elements are
unintentionally mixed, product defects may increase and mechanical
properties may be greatly reduced, and thus elements, such as Bi
and Si, are desirably used as little as possible for convenience of
the production site.
[0008] In addition, the alloy of Patent Document 1 has a problem in
that in a range in which the Zn content is high, the
dezincification corrosion is prone to occur, and has a property in
which in a range in which the Pb content is high, the lead leaching
level fails to be satisfied. Moreover, since Bi is contained, there
has been a recycle problem as described above. Further, if in a
range in which the Zn content is high and the Sn content is low, Zr
is contained, the improvement in properties is effectively made
during a casting process having a small temperature range of
solidification, such as that of solidification from a semi-solid
state, whereas if in a range in which the Zn content is low and the
Sn content is high, Zr is contained and in a process of casting a
metal, which is not in a semi-solid state but completely liquid, in
a mold, a temperature range to solidification is large so that a
compound of Zr may be generated and shrinkage cavities may be
facilitated to reduce mechanical properties.
[0009] Moreover, in the alloy of Patent Document 2, since Bi is
contained, there has been a recycle problem as described above.
[0010] Accordingly, an object of the present invention is to
provide a copper alloy for use in a member for water works, which
has suitable mechanical properties and castability, while not only
inhibiting lead leaching but also maintaining the
recyclability.
Means for Solving the Problems
[0011] The present invention has solved the above mentioned
problems by a copper alloy for use in a member for water works, the
copper alloy consisting of: 0.5% by mass or less of Ni; 12% by mass
or more and 21% by mass or less of Zn; 1.4% by mass or more and
4.5% by mass or less of Sn, a total content of Zn and Sn being
23.5% by mass or less; 0.005% by mass or more and 0.15% by mass or
less of P; 0.05% by mass or more and 0.30% by mass or less of Pb;
less than 0.2% by mass of Bi; and the balance, wherein the balance
is Cu and unavoidable impurities.
[0012] Bi is limited to be less than 0.2% by mass so as to be
capable of being used even when mixed with another alloy in
recycling. Meanwhile, even when Bi is less than 0.2% by mass as
described above, if Pb is 0.30% by mass or less, effects of
improving properties, such as the machinability, due to addition of
Pb can be exhibited, while leaching lead amount regulations are
satisfied. Further, values of Zn and Sn are adjusted together so as
to be such a blending as to be capable of exhibiting sufficient
mechanical properties without using Bi which has a large influence
in recycling.
[0013] Moreover, Ni is 0.5% by mass or less so as to be capable of
inhibiting an occurrence of shrinkage cavities.
[0014] Further, this copper alloy may contain in a limited manner
an element which may be mixed therein as another unavoidable
impurity. Note that its total amount is required to fall within
such as range as not to inhibit effects of the present invention,
and is preferably less than 1.0% by mass and the content of each of
such element is preferably less than 0.5% by mass.
Effects of the Invention
[0015] According to the present invention, it is possible to obtain
a copper alloy which is also excellent in recyclability and has
good mechanical properties by limiting the content of Pb and not
containing Bi so as to be capable of producing a member for water
works in which safety is further secured.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a schematic view of type A defined in JISH 5120
for obtaining a sample used in a tensile test evaluation method in
Examples.
[0017] FIG. 2 is a schematic view of a type 4 test specimen defined
in JISZ 2241 used in a tensile test evaluation method in
Examples.
[0018] FIG. 3 is a structural view illustrating a structure of an
erosion-corrosion test.
[0019] FIGS. 4(a) and 4(b) are views illustrating a spiral-shaped
test mold used in a flowability test in Examples.
[0020] FIG. 5 is a structural view of a step-shaped mold used in a
shrinkage cavity test in Examples.
[0021] FIG. 6 shows photographs illustrating the results of a
liquid penetrant testing in Examples.
MODE FOR CARRYING OUT THE INVENTION
[0022] The present invention will now be described in detail.
[0023] The present invention relates to a copper alloy for use in a
member for water works, which contains Pb in a limited manner and
is blended without containing Bi.
[0024] In the above mentioned copper alloy, a Zn content is
required to be 12% by mass or more, and preferably 13% by mass or
more. The Zn content of less than 12% by mass results in producing
curled machining chips so as to reduce the machinability.
Meanwhile, the Zn content is required to be 21% by mass or less,
and is preferably 20% by mass or less and more preferably 18% by
mass or less. Too high a Zn content results in not only a reduction
in mechanical properties but also an increase of zinc residue so as
to complicate the casting.
[0025] In the above mentioned copper alloy, a Sn content is
required to be 1.4% by mass or more, and preferably 2.0% by mass or
more. The Sn content of less than 1.4% by mass results in producing
curled machining chips so as to reduce the machinability, similarly
to effects of Zn. Moreover, an oxide film which protects a surface
of a member for water works is removed by the water stream so that
the resistance to erosion-corrosion in which the corrosion of the
alloy progresses becomes insufficient. Meanwhile, the Sn content is
required to be 4.5% by mass or less, and is preferably 4.3% by mass
or less and more preferably 3.0% by mass or less. This is because
too high a Sn content results in a reduced elongation and/or an
occurrence of shrinkage cavities during the sand casting.
[0026] In the above mentioned copper alloy, a total content of Zn
and Sn is required to be 23.5% by mass or less, and preferably
21.0% by mass or less. If an amount of Zn solid-solubilized in Cu
is too high, the solid solubility of Sn is reduced to result in an
increased concentration of Sn in the residual liquid phase during
the solidification, and as a result, the crystallization of
.beta.-phase due to peritectic reaction is more likely to occur.
Eventually, .alpha.+.delta. phases, composed of .alpha.-phases
scattered in hard .delta.-phases (Cu.sub.31Sn.sub.8), are generated
between dendrites, resulting in a reduction in the tensile
strength. Further, the presence of Bi dispersed in the vicinity of
the .alpha.+.delta. phases, during the generation thereof, leads to
a synergistic reduction in the mechanical properties of the alloy.
In addition, when the casting is carried out under the conditions
of low solidification rate, such as when producing a thick wall
casting or sand casting, there is a potential risk that the
resulting casting may develop casting defects during the final
solidification, such as a defect referred to as "tin sweat", a
state where Sn exudes from the surface of the alloy as if it is
sweating, or shrinkage cavity defects. If the total content of Zn
and Sn exceeds 23.5% by mass, a reduction in mechanical properties
and an occurrence of casting defects will be unignorable.
[0027] In the above mentioned copper alloy, a P content is required
to be 0.005% by mass or more, and preferably 0.01% by mass or more.
Since P produces a deoxidizing effect, too low a P content reduces
the deoxidizing effect during the casting, resulting not only in an
increased occurrence of gas defects, but also in a decreased
flowability of molten metal due to oxidation of the molten metal.
On the other hand, the P content is required to be 0.15% by mass or
less, and preferably 0.05% by mass or less. If the P content is too
high, P reacts with water in the mold to increase the occurrence of
gas defects and shrinkage cavity defects in the resulting casting,
and the mechanical properties thereof are also reduced. On the
other hand, since the above mentioned copper alloy contains a high
amount of Zn, gas absorption is reduced due to the degassing effect
of Zn. This allows for production of a casting with little casting
defects, even if the P content is low as compared to a
representative bronze alloy, JIS
[0028] In the above mentioned copper alloy, a Pb content is
required to be 0.05% by mass or more, and preferably 0.07% by mass
or more. This is because while Pb is contained slightly so as to
greatly improve the machinability, the Pb content of less than
0.05% by mass results in its effects insufficient. On the other
hand, the Pb content is required to be 0.30% by mass or less, and
preferably 0.20% by mass or less. Pb is an element whose leaching
should be prevented as much as possible, and if the Pb content
exceeds 0.30% by mass, it will be difficult to satisfy a leaching
reference value in a leaching test.
[0029] In the above mentioned copper alloy, a Ni content is
required to be 0.5% by mass or less. Ni may not be contained but
produces effects exhibiting stable mechanical properties, and, at
the same time, produces effects of inhibiting an occurrence of
shrinkage cavities, which facilitates production of a decent
casting. On the other hand, if the Ni content exceeds 0.5% by mass,
the machinability is prone to be reduced.
[0030] The above mentioned copper alloy may contain another
impurities as the balance, in addition to Cu, within such a range
as not to inhibit effects of the present invention. Note that the
content is preferably restricted to such an extent as to be
contained as unavoidable impurities which are unavoidably contained
in view of problems of raw materials and problems during
production. A total amount of the elements which constitute the
unavoidable impurities is preferably less than 1.0% by mass, and
more preferably less than 0.5% by mass. This is because, if too
much unexpected elements are incorporated in the alloy, even if the
above mentioned elements are contained within the above mentioned
ranges, there is a potential risk that the physical properties of
the alloy may be deteriorated. Further, a content of each element
is preferably less than 0.4% by mass.
[0031] Among the elements which constitute above mentioned
unavoidable impurities, a content of Bi is preferably less than
0.2% by mass, more preferably less than 0.1% by mass, and still
more preferably less than the detection limit. Since Bi is not
solid-solubilized in Cu, but dispersed, a higher Bi content is more
prone to cause a reduction in the strength, such as the tensile
strength. Further, such dispersed Bi leads to a tendency to easily
cause an occurrence of shrinkage cavities during the sand casting.
Further, too high a Bi content results in an occurrence of various
demerits, such as a reduction in mechanical properties caused by
mixture of Bi into an alloy to be recycled in recycling a member
for water works produced using the above mentioned copper alloy so
that the member for water works is required to be collected
separately.
[0032] Among the elements that constitute the unavoidable
impurities which the above mentioned copper alloy may contain, a
content of Si is preferably less than 0.01% by mass, and more
preferably less than 0.005% by mass. Too high a Si content results
in facilitation of shrinkage cavities so that a decent casting
fails to be produced.
[0033] Among the elements that constitute the unavoidable
impurities which the above mentioned copper alloy may contain, a
content of Al is preferably less than 0.01% by mass, and more
preferably less than 0.005% by mass. Similarly to Si, too high an
Al content results in facilitation of shrinkage cavities so that a
decent casting fails to be produced.
[0034] Among the elements that constitute the unavoidable
impurities which the above mentioned copper alloy may contain, a
content of Sb is preferably less than 0.05% by mass, more
preferably less than 0.03% by mass, and still more preferably less
than the detection limit. Since Sb tends to form Cu--Sn--Sb-based
intermetallic compounds, which tend to reduce the toughness of the
alloy, there is a risk that the mechanical properties of the alloy
may be reduced.
[0035] Among the elements that constitute the unavoidable
impurities which the above mentioned copper alloy may contain, a
content of Zr is preferably less than 0.01% by mass, more
preferably less than 0.0005% by mass, and still more preferably
less than the detection limit. Containing Zr results in degradation
of mechanical properties and facilitation of shrinkage cavities so
that a decent casting fails to be produced.
[0036] Among the elements that constitute the unavoidable
impurities which the above mentioned copper alloy may contain, the
content of each of the unavoidable impurities is preferably less
than 0.4% by mass, more preferably less than 0.2% by mass, and
still more preferably less than the detection limit. Examples of
such impurities include Fe, Mn, Cr, Mg, Ti, Te, Se, Cd, etc. Among
those in particular, the content of Se and Cd, which are known to
be toxic, is each desirably less than 0.1% by mass, and more
preferably less than the detection limit.
[0037] Note that, the values of the content of the elements as
described in the present invention denote the values of the content
of elements in the resulting casting or forging, not the content
thereof in the raw materials.
[0038] The balance of the above mentioned copper alloy is Cu. The
copper alloy according to the present invention can be produced by
a common method for producing a copper alloy. When producing a
member for water works using the thus obtained copper alloy, a
common casting method (such as sand casting) can be used. For
example, a member for water works can be prepared by a method in
which an alloy is melted using an oil furnace, gas furnace, or high
frequency induction melting furnace, and then cast using molds in
various shapes.
EXAMPLES
[0039] Examples in which the copper alloy of the present invention
was actually produced will now be described. Firstly, the testing
methods for copper alloy will be described.
<Mechanical Properties Test>
[0040] A sample prepared by being cast into a shape of type A
sample defined in JISH 5120 was processed into a type 4 test
specimen defined in JISZ 2241. Specific shapes are each indicated
in FIGS. 1 and 2. Among those, a type A test specimen in FIG. 1 is
a hatched portion in the figure, and the unit of the size is mm.
Moreover, a diameter d.sub.o is 14.+-.0.5 mm, an original gauge
length of the test specimen L.sub.o is 50 mm, a length of a
parallel portion L.sub.c is 60 mm or more, and a radius of a
shoulder portion R is 15 mm or more.
[0041] With respect to this test specimen, the tensile strength and
elongation were then measured in accordance with JIS Z2241. The
mechanical properties of each of the test specimens were evaluated
based on the thus obtained values. [0042] The tensile strength was
evaluated as follows: 195 MPa or more was evaluated as
".smallcircle."; and less than 195 MPa was evaluated as "x". [0043]
The elongation was evaluated as follows: 15% or more was evaluated
as ".smallcircle."; and less than 15% was evaluated as "x".
[0044] Note that, these threshold values are reference values for
JIS H5120 CAC406 generally used in a member for water works.
<Erosion-Corrosion Test>
[0045] A sample prepared by casting in a metal mold having a size
of 20 mm diameter.times.120 mm (length) was processed to have a
cylindrical shape having a size of 16 mm diameter, as illustrated
in FIG. 3, so as to be a test specimen 12, a nozzle 11 having a
diameter of 1.6 mm is provided at a position spaced apart from this
test specimen 12 by 0.4 mm, 1% CuCl.sub.2 solution 13 was made to
flow from the nozzle 11 toward the sample at the flow rate of 0.4
L/min in the normal flow direction for 5 hours, and the weight loss
(abrasion amount) and the maximum depth of the sample before and
after the test were measured. [0046] The abrasion amount was
evaluated as follows: less than 150 mg was evaluated as
".smallcircle."; 150 mg or more and less than 200 mg was evaluated
as ".DELTA."; and 200 mg or more was evaluated as "x". [0047] The
maximum depth was evaluated as follows: less than 100 .mu.m was
evaluated as ".smallcircle."; 100 .mu.m or more and less than 150
.mu.m was evaluated as ".DELTA."; and 150 .mu.m or more was
evaluated as "x".
<Machinability Test and Drilling Test>
[0048] For each of the alloys, the drilling test using a drilling
machine was carried out. The drilling test was carried out using
each of the samples formed by machining to cylindrical samples
having a size of 18 mm diameter.times.20 mm (height), and using a
drilling machine, times required to drill a hole having a 5 mm
depth from a deep part of the cylinder were measured under the
drilling conditions as indicated in Table 1. Times with the results
of less than 6 seconds were evaluated as ".smallcircle."; times
with the results of 6 seconds or more and less than 7 seconds were
evaluated as ".DELTA."; and times with results of 7 seconds or more
were evaluated as "x".
TABLE-US-00001 TABLE 1 Item Conditions Cutting tool Material
High-speed steel (SDD0600 Cutting Diameter: 6 mm manufactured by
diameter Mitsubishi Total 102 mm Corporation) length Flute 70 mm
length Point 118.degree. angle Load 25 kg Rotational speed 960 rpm
Drilling depth 5 mm
<Test for Flowability>
[0049] Each of the copper alloys of Examples and Comparative
Examples was heated and melted, and then cast using a spiral-shaped
test mold as illustrated in FIGS. 4(a) and 4(b), to obtain a
spiral-shaped test specimen. Since each of the alloys varying in
its Zn content has a different temperature at which solidification
starts, it is impossible to evaluate the proper flowability of
molten metal for each of the alloys, using the same pouring
temperature. Therefore, the temperature at which the solidification
starts was measured for each of the alloys, by thermal analysis
method, and then the casting was carried out at a temperature of
+110.degree. C. above the measured temperature. Then, the flow
length of the spiral-shaped portion of the thus cast spiral-shaped
test specimen was measured. Flow lengths with the results of 300 mm
or more were evaluated as ".smallcircle."; flow lengths with the
results of 280 mm or more and less than 300 mm were evaluated as
".DELTA."; and flow lengths with results of less than 280 mm were
evaluated as "x".
<Test for Casting Defects>
<Liquid Penetrant Testing Using Step-Shaped Sample>
[0050] For each of the alloys, liquid penetrant testing was
performed using a step-shaped sample, and evaluation of casting
defects was performed. "-" in the Table denotes that the evaluation
was not carried out. Specifically the testing was carried out as
follows. A step-shaped CO.sub.2 mold as illustrated in FIG. 5 was
prepared (casting temperature at 1120.degree. C.), which was
provided with three stepped portions with varying wall thicknesses
of 10, 20 and 30 mm, so that the feeding effect was reduced and the
resulting casting was more likely to develop casting defects, and
the thus obtained casting was cut in half in the middle, and the
liquid penetrant testing was carried out in accordance with JIS
Z2343 so that occurrences of casting defects and minute gaps in
this liquid penetrant testing were examined. Those in which no
defect indications such as defects of shrinkage cavities and gas
defects were observed in a portion having a thickness of 10 and 20
mm were evaluated as ".smallcircle."; those in which some defect
indications were not observed in the portion having a thickness of
10 mm but observed in the portion having a thickness of 20 mm were
evaluated as ".DELTA."; and those in which some defect indications
were observed in the portions having a thickness of 10 and 20 mm
were evaluated as "x". A portion having a thickness of 30 mm was
not evaluated.
<Production Method>
[0051] Materials containing each of the elements were mixed, and
melted in a high frequency induction melting furnace, followed by
casting using a CO.sub.2 mold to produce samples each having the
composition as indicated in Table 2. Note that all the values of
the content of the elements are expressed in % by mass and are
values measured after the production. Further, a conventionally
used bronze material containing lead, JIS H5120 CAC406, was used as
Comparative Example 12, which was used for the comparison of
physical properties. Its content is also indicated in the Table.
The following tests were carried out for each of the resulting
copper alloys. Note that "-" in the Table denotes to be less than
the detection limit. Note that, the content of each of B, Bi, Sb,
Al, Si, and Fe was less than the detection limit, in each of
Examples and Comparative Examples except Comparative Example 11.
The overall evaluation was carried out according to the following
standards: those having ".smallcircle." evaluation in all the tests
performed were defined as ".smallcircle."; those having at least
one ".DELTA." evaluation in any of the tests were defined as
".DELTA."; and those having as least one "x" evaluation in any of
the tests were defined as "x".
TABLE-US-00002 TABLE 2 Cu Zn Sn Zn + Sn P Pb Ni Bi Overall Balance
12~21 1.4~4.5 .ltoreq.23.5 0.005-0.15 0.05~0.30 .ltoreq.0.5 <0.2
Evaluation Comparative Balance 10.70 2.41 13.11 0.025 0.21 -- -- x
example 1 Example 1 Balance 12.00 2.52 14.52 0.026 0.22 -- --
.smallcircle. Example 2 Balance 14.89 2.47 17.36 0.025 0.22 -- --
.smallcircle. Example 3 Balance 18.05 2.53 20.58 0.024 0.21 -- --
.smallcircle. Example 4 Balance 20.75 2.41 23.16 0.026 0.21 -- --
.DELTA. Comparative Balance 14.95 0.99 15.94 0.023 0.21 -- -- x
Example 2 Example 5 Balance 14.95 1.43 16.38 0.022 0.21 -- --
.DELTA. Example 2 Balance 14.89 2.47 17.36 0.025 0.22 -- --
.smallcircle. Example 6 Balance 17.58 4.39 21.97 0.024 0.21 -- --
.smallcircle. Example 7 Balance 14.91 4.50 19.41 0.025 0.22 -- --
.DELTA. Comparative Balance 14.71 4.92 19.63 0.023 0.22 -- -- x
Example 3 Example 5 Balance 14.95 1.43 16.38 0.022 0.21 -- --
.smallcircle. Example 3 Balance 18.05 2.53 20.58 0.024 0.21 -- --
.smallcircle. Example 4 Balance 20.75 2.41 23.16 0.026 0.21 -- --
.DELTA. Comparative Balance 19.79 4.51 24.30 0.027 0.20 -- -- x
Example 4 Comparative Balance 14.74 2.26 17.00 0.004 0.21 -- -- x
Example 5 Example 8 Balance 14.87 2.27 17.14 0.007 0.21 -- --
.DELTA. Example 2 Balance 14.89 2.47 17.36 0.025 0.22 -- --
.smallcircle. Example 9 Balance 15.03 2.30 17.33 0.058 0.21 -- --
.DELTA. Example 10 Balance 15.09 2.41 17.50 0.130 0.23 -- --
.DELTA. Comparative Balance 14.83 2.30 17.13 0.192 0.22 -- -- x
Example 6 Comparative Balance 15.01 2.36 17.37 0.032 0.03 -- -- x
Example 7 Example 11 Balance 15.10 2.38 17.48 0.029 0.06 -- --
.DELTA. Example 2 Balance 14.89 2.47 17.36 0.025 0.22 -- --
.smallcircle. Example 12 Balance 15.19 2.47 17.66 0.029 0.27 -- --
.smallcircle. Comparative Balance 15.18 2.39 17.57 0.029 0.32 -- --
Pb Example 8 leaching x Example 2 Balance 14.89 2.47 17.36 0.025
0.22 -- -- .smallcircle. Example 13 Balance 15.32 2.38 17.70 0.028
0.21 0.11 -- .DELTA. Example 14 Balance 14.36 2.41 16.77 0.023 0.21
0.31 -- .DELTA. Example 15 Balance 14.27 2.35 16.62 0.018 0.21 0.50
-- .DELTA. Comparative Balance 14.93 2.25 17.18 0.026 0.20 0.67 --
x Example 9 Comparative Balance 14.62 2.52 17.14 0.025 0.21 1.00 --
x Example 10 Comparative Balance 15.35 2.26 17.61 0.028 0.20 -- 0.3
x Example 11 Comparative Balance 5.14 5.78 10.92 0.021 5.38 0.15 --
Pb Example 12 leaching x
TABLE-US-00003 TABLE 3 Machinability Erosion-Corrosion Properties
Drilling test Maximum depth Abrasion amount .smallcircle. less than
.smallcircle. less than .smallcircle. less than 6 seconds 100 .mu.m
150 mg .DELTA. 6 seconds .DELTA. 100 .mu.m .DELTA. 150 mg
Mechanical Properties or more or more and or more and Tensile and
less than Flowability less than less than strength Elongation 7
seconds Flow Casting Defects 150 .mu.m 200 mg 195 MPa 15% or x 7
seconds Flowability length Defects Defects x 150 .mu.m x 200 mg
Overall or more more or more evaluation (mm) evaluation type or
more or more Evaluation Comparative .smallcircle. 241 .smallcircle.
38.0 x 7.01 -- -- -- -- -- -- -- -- x Example 1 Example 1
.smallcircle. 227 .smallcircle. 32.0 .smallcircle. 5.54 -- -- -- --
-- -- -- -- .smallcircle. Example 2 .smallcircle. 246 .smallcircle.
44.0 .smallcircle. 5.64 .smallcircle. 318 .smallcircle. --
.smallcircle. 73 .smallcircle. 104 .smallcircle. Example 3
.smallcircle. 220 .smallcircle. 38.0 .smallcircle. 5.64 -- -- -- --
-- -- -- -- .smallcircle. Example 4 .smallcircle. 236 .smallcircle.
44.0 .DELTA. 6.98 -- -- -- -- -- -- -- -- .DELTA. Comparative
.smallcircle. 228 .smallcircle. 48.0 .DELTA. 6.39 -- -- -- -- x 409
x 202 x Example 2 Example 5 .smallcircle. 238 .smallcircle. 55.0
.smallcircle. 5.20 -- -- -- -- .DELTA. 116 .DELTA. 152 .DELTA.
Example 2 .smallcircle. 246 .smallcircle. 44.0 .smallcircle. 5.64
.smallcircle. 318 .smallcircle. -- .smallcircle. 73 .smallcircle.
104 .smallcircle. Example 6 .smallcircle. 208 .smallcircle. 19.3 --
-- -- -- -- -- -- -- -- -- .smallcircle. Example 7 .smallcircle.
243 .smallcircle. 25.0 .DELTA. 6.07 -- -- -- -- .smallcircle. 18
.smallcircle. 65 .DELTA. Comparative .smallcircle. 202 x 14.0 x
9.54 -- -- -- -- .smallcircle. 27 .smallcircle. 61 x Example 3
Example 5 .smallcircle. 238 .smallcircle. 55.0 .smallcircle. 5.20
-- -- -- -- .DELTA. 116 .DELTA. 152 .smallcircle. Example 3
.smallcircle. 220 .smallcircle. 38.0 .smallcircle. 5.64 -- -- -- --
-- -- -- -- .smallcircle. Example 4 .smallcircle. 236 .smallcircle.
44.0 .DELTA. 6.98 -- -- -- -- -- -- -- -- .DELTA. Comparative x 192
x 14.0 -- -- -- -- -- -- -- -- -- -- x Example 4 Comparative
.smallcircle. 231 .smallcircle. 38.0 .DELTA. 6.05 x 258
.smallcircle. -- -- -- -- -- x Example 5 Example 8 .smallcircle.
243 .smallcircle. 42.0 .DELTA. 6.73 .DELTA. 294 .smallcircle. -- --
-- -- -- .DELTA. Example 2 .smallcircle. 246 .smallcircle. 44.0
.smallcircle. 5.64 .smallcircle. 318 .smallcircle. -- .smallcircle.
73 .smallcircle. 104 .smallcircle. Example 9 .smallcircle. 235
.smallcircle. 41.0 .DELTA. 6.82 .smallcircle. 358 .smallcircle. --
-- -- -- -- .DELTA. Example 10 -- -- -- -- -- -- .smallcircle. 394
.DELTA. Shrinkage -- -- -- -- .DELTA. cavities Comparative
.smallcircle. 263 .smallcircle. 52.0 .smallcircle. 5.92 x 258 x
Shrinkage -- -- -- -- x Example 6 cavities Comparative
.smallcircle. 235 .smallcircle. 43.0 x 7.39 -- -- -- -- -- -- -- --
x Example 7 Example 11 .smallcircle. 249 .smallcircle. 59.0 .DELTA.
6.25 -- -- -- -- -- -- -- -- .DELTA. Example 2 .smallcircle. 246
.smallcircle. 44.0 .smallcircle. 5.64 .smallcircle. 318
.smallcircle. -- .smallcircle. 73 .smallcircle. 104 .smallcircle.
Example 12 .smallcircle. 244 .smallcircle. 49.0 .smallcircle. 5.15
-- -- -- -- -- -- -- -- .smallcircle. Comparative .smallcircle. 229
.smallcircle. 42.0 .smallcircle. 4.83 -- -- -- -- -- -- -- -- Pb
Example 8 leaching x Example 2 .smallcircle. 246 .smallcircle. 44.0
.smallcircle. 5.64 .smallcircle. 318 .smallcircle. -- .smallcircle.
73 .smallcircle. 104 .smallcircle. Example 13 .smallcircle. 242
.smallcircle. 59.0 .DELTA. 6.70 -- -- -- -- -- -- -- -- .DELTA.
Example 14 -- -- -- -- .DELTA. 6.48 -- -- -- -- -- -- -- -- .DELTA.
Example 15 -- -- -- -- .DELTA. 6.74 -- -- -- -- -- -- -- -- .DELTA.
Comparative .smallcircle. 250 .smallcircle. 50.0 x 7.37 -- -- -- --
-- -- -- -- x Example 9 Comparative -- -- -- -- x 7.71 -- -- -- --
-- -- -- -- x Example 10 Comparative x 180 .smallcircle. 22.0
.smallcircle. 4.12 -- -- -- -- -- -- -- -- x Example 11 Comparative
.smallcircle. 250 .smallcircle. 33.2 -- 2.15 .DELTA. 298
.smallcircle. -- -- -- -- -- Pb Example 12 leaching x
[0052] First, CAC406 of Comparative Example 12 will be described.
CAC406 has mechanical properties, such as a tensile strength of 195
MPa or more and an elongation of 15% or more, which are values
defined in JIS. Moreover, since CAC406 contains 5.38% by mass of
Pb, good results were obtained in the drilling test. Further, the
flow length measured in the test for flowability of molten metal
was 298 mm, which was evaluated as ".DELTA.". On the other hand,
since from 4 to 6% by mass of Pb is contained, Comparative Example
12 has a problem in lead leaching.
[0053] Firstly, Comparative Example 1 and Examples 1 to 4 were
prepared to have a varying Zn content, with the contents of
elements other than Zn being as close to each other as possible.
These were arranged in the first group in Table 2 and Table 3 in
ascending order of Zn content. With respect to the mechanical
properties, each showed values exceeding the tensile strength of
195 MPa and the elongation of 15%, whereas in Comparative Example 1
in which Zn is less than 12% by mass, the time required for
machining was too long. On the other hand, in Example 4 in which Zn
is nearly 21% by mass which is the upper limit, it was found that
the machinability tended to be reduced.
[0054] Next, with Example 2 as a reference, Comparative Example 2,
Examples 5, 6, and 7, and Comparative Example 3 were prepared to
have a varying Sn content, with the contents of elements other than
Sn being as close to each other as possible. These were arranged in
the second group in Table 2 and Table 3 in ascending order of the
Sn content. In Example 5 in which the Sn content is 1.43% by mass
which is close to the lower limit value, the erosion-corrosion
resistance had a tendency to be slightly reduced, and in
Comparative Example 2 in which the Sn content is 0.99% by mass, the
erosion-corrosion resistance remarkably lacked. On the other hand,
in Example 7 in which Zn is 4.5% by mass, the machinability had a
tendency to be reduced, and in Comparative Example 3 in which the
Sn content is 4.92% by mass which exceeds 4.5% by mass, a problem
in elongation and machinability occurred.
[0055] Next, Examples 5, 3, and 4 were arranged in ascending order
of the total content of Zn+Sn in Table 2, and Comparative Example 4
in which the content of Zn+Sn further exceeds as compared to those
and exceeds 23.5% by mass was prepared, and those were arranged in
the third group in Table 2 and Table 3 in ascending order of the
total content of Zn+Sn. In Comparative Example 4, both the tensile
strength and the elongation were greatly reduced.
[0056] Next, with Example 2 as a reference, Comparative Example 5,
Examples 8 and 9, and Comparative Example 6 were prepared to have a
varying P content, with the contents of elements other than P being
as close to each other as possible. These were arranged in the
fourth group in Table 2 and Table 3 in ascending order of the P
content. In each of Comparative Example 5 in which the P content is
less than 0.005% by mass and Comparative Example 6 in which the P
content exceeds 0.15% by mass, there consequently occurred a
problem in flowability. Further, the results for the liquid
penetrant testing are indicated in FIG. 6. In Comparative Example 6
in which the P content exceeds 0.15% by mass, there entirely
occurred shrinkage cavities. Note that in the photograph, the
portions having a thickness of 30 mm were not estimated and parts
in which red and fine spots are generated in a thinner portion were
examined. In Examples other than Comparative Example 6, at the
portions having a thickness of 20 mm or less, no spots were found,
which provided good results.
[0057] Next, with Example 2 as a reference, Comparative Example 7,
Examples 10, Example 11, and Comparative Example 8 were prepared to
have a varying Pb content, with the contents of elements other than
Pb being as close to each other as possible. These were arranged in
the fifth group in Table 2 and Table 3 in ascending order of the Pb
content. In Comparative Example 7 in which the Pb content is 0.03%
by mass which is less than 0.05% by mass, there consequently
occurred a problem in machinability.
[0058] Further, with compositions similar to that of Example 2,
Examples 13, 14, and 15 and Comparative Examples 9 and 10 were
prepared to contain Ni. None of those had a problem in mechanical
properties. However, in Comparative Examples 9 and 10 in which the
Ni content exceeds 0.5% by mass, there occurred a problem in
machinability.
[0059] Still further, with a composition similar to that of Example
2, Comparative Example 11 was prepared to contain 0.3% by mass of
Bi. The tensile strength was greatly reduced so that there occurred
a problem in mechanical properties. Moreover, this content
exhibited a problem in view of recyclability.
* * * * *