U.S. patent application number 10/597568 was filed with the patent office on 2008-10-16 for master alloy for casting a modified copper alloy and casting method using the same.
Invention is credited to Keiichiro Oishi.
Application Number | 20080253924 10/597568 |
Document ID | / |
Family ID | 35839218 |
Filed Date | 2008-10-16 |
United States Patent
Application |
20080253924 |
Kind Code |
A1 |
Oishi; Keiichiro |
October 16, 2008 |
Master Alloy for Casting a Modified Copper Alloy and Casting Method
Using the Same
Abstract
An advantage of the invention is to provide a master alloy used
in a casting of a modified copper alloy, grains of which can be
refined during a melt-solidification, and also a method of casting
a modified copper alloy using the same. In order to achieve the
advantage, master alloy for casting a copper alloy in a form of Cu:
40 to 80%, Zr: 0.5 to 35% and the balance of Zn; and Cu: 40 to 80%,
Zr: 0.5 to 35%, P: 0.01 to 3% and the balance of Zn are used, and
thus grain-refined copper alloy casting products are obtained.
Inventors: |
Oishi; Keiichiro; (Osaka,
JP) |
Correspondence
Address: |
GRIFFIN & SZIPL, PC
SUITE PH-1, 2300 NINTH STREET, SOUTH
ARLINGTON
VA
22204
US
|
Family ID: |
35839218 |
Appl. No.: |
10/597568 |
Filed: |
August 10, 2005 |
PCT Filed: |
August 10, 2005 |
PCT NO: |
PCT/JP2005/014678 |
371 Date: |
July 31, 2006 |
Current U.S.
Class: |
420/477 ;
164/57.1; 420/587 |
Current CPC
Class: |
A61P 11/06 20180101;
C22C 1/03 20130101; C22C 30/06 20130101; C22C 30/02 20130101; B22D
21/025 20130101; B22D 21/022 20130101; C22C 9/00 20130101; C22C
1/06 20130101; C22F 1/08 20130101; C22C 9/04 20130101; B22D 27/00
20130101 |
Class at
Publication: |
420/477 ;
420/587; 164/57.1 |
International
Class: |
C22C 9/04 20060101
C22C009/04; C22C 9/00 20060101 C22C009/00; B22D 27/00 20060101
B22D027/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 10, 2004 |
JP |
2004-233952 |
Claims
1-13. (canceled)
14. A master alloy for casting a copper alloy, comprising: Cu: 40
to 80 wt. %; Zr: 0.5 to 35 wt. %; and the balance of Zn.
15. The master alloy for casting a copper alloy, according to claim
14, further comprising: P: 0.01 to 3 wt. %.
16. The master alloy for casting a copper alloy according to claim
14, further comprising: one element selected from the group
consisting of Mg: 0.01 to 1 wt. %, Al: 0.01 to 5 wt. %, Sn: 0.1 to
5 wt. %, B: 0.01 to 0.5 wt. %, Mn: 0.01 to 5 wt. % and Si: 0.01 to
1 wt. %.
17. The master alloy for casting a copper alloy according to claim
14, wherein said Cu occupies 50 to 65 wt. %, and said Zr occupies 1
to 10 wt. %.
18. The master alloy for casting a copper alloy according to claim
14, wherein said master alloy is an ingot formed in a shape of a
boat, continuous casting material formed in a shape of a rod or
wire, or hot extrusion material formed in a shape of a rod or
wire.
19. A master alloy for casting a copper alloy, comprising: Cu: 40
to 80 wt. %; Zr: 0.5 to 35 wt. %; P: 0.01 to 3 wt. %; and the
balance of Zn.
20. The master alloy for casting a copper alloy according to claim
19, further comprising: one element selected from the group
consisting of Mg: 0.01 to 1 wt. %, Al: 0.01 to 5 wt. %, Sn: 0.1 to
5 wt. %, B: 0.01 to 0.5 wt. %, Mn: 0.01 to 5 wt. % and Si: 0.01 to
1 wt. %.
21. The master alloy for casting a copper alloy according to claim
19, wherein said Cu occupies 50 to 65 wt. %, and said Zr occupies 1
to 10 wt. %.
22. The master alloy for casting a copper alloy according to claim
19, wherein said master alloy is an ingot formed in a shape of a
boat, continuous casting material formed in a shape of a rod or
wire, or hot extrusion material formed in a shape of a rod or
wire.
23. A method of casting a modified copper alloy from a molten
copper alloy containing Zr and P, the method comprising the steps
of: providing a molten copper alloy; adding at least Zr in the form
of Cu--Zn--Zr alloy or Cu--Zn--Zr--P alloy into said molten copper
alloy; and casting said molten copper alloy.
24. The method of casting a modified copper alloy from a molten
copper alloy containing Zr and P according to claim 23, wherein Zr
is added in the form of Cu--Zn--Zr--P alloy and concentration of
the metal Zr in the molten alloy is in a range of 5 ppm or more in
the presence of P when the molten copper alloy begins to
solidify.
25. The method of casting a modified copper alloy from a molten
copper alloy containing Zr and P according to claim 24, wherein
concentration of the metal Zr in the molten alloy is in a range of
20 to 500 ppm in the presence of P when the molten copper alloy
begins to solidify.
26. The method of casting a modified copper alloy from a molten
copper alloy containing Zr and P according to claim 24, wherein an
amount ratio of P to Zr in said molten copper alloy satisfies
0.5<P/Zr<150.
27. The method of casting a modified copper alloy from a molten
copper alloy containing Zr and P according to claim 26, wherein the
amount ratio of P to Zr in said molten copper alloy satisfies
1<P/Zr<50.
28. The method of casting a modified copper alloy from a molten
copper alloy containing Zr and P according to claim 27, wherein the
amount ratio of P to Zr in said molten copper alloy satisfies
1.2<P/Zr<25.
29. The method of casting a modified copper alloy from a molten
copper alloy containing Zr and P according to claim 24, wherein
primary alpha phases begin to be crystallized during
solidification.
30. The method of casting a modified copper alloy from a molten
copper alloy containing Zr and P according to claim 29, wherein
beta phases are crystallized by peritectic or eutectic
reactions.
31. The method of casting a modified copper alloy from a molten
copper alloy containing Zr and P according to claim 29, wherein one
or more phases selected from the group consisting of kappa, gamma,
delta and mu phases are precipitated in an alpha phase matrix by a
solid phase reaction.
32. The method of casting a modified copper alloy from a molten
copper alloy containing Zr and P according to claim 23, wherein a
copper alloy to be modified is one selected from the group
consisting of Cu--Zn, Cu--Zn--Si, Cu--Zn--Sn, Cu--Zn--Al,
Cu--Zn--Bi, Cu--Zn--Pb, Cu--Zn--Si--Mn, Cu--Zn--Si--Pb,
Cu--Zn--Si--Sn, Cu--Zn--Si--Al, Cu--Zn--Sn--Pb, Cu--Zn--Sn--Bi,
Cu--Zn--Sn--Al, Cu--Sn, Cu--Sn--Pb, Cu--Sn--Bi, Cu--Al, Cu--Al--Si,
Cu--Si, Cu--Cr, Cu--Pb, Cu--P, and Cu--Te.
33. The method of casting a modified copper alloy from a molten
copper alloy containing Zr and P according to claim 32, wherein
said copper alloy to be modified satisfies
60<Cu-3.5Si-1.8Al-0.5X+0.5Y+Mn<90 where X is Sn, Sb, As or Mg
and Y is Pb, Bi, Se, Te or Cr.
Description
TECHNICAL FIELD
[0001] The present invention relates to a master alloy used for
casting a modified copper alloy having refined grains, which is
used in a casting method such as continuous casting, semi-solid
metal casting, sand casting, permanent mold casting, low pressure
die casting, die casting, lost wax casting, up casting, squeeze,
centrifugal casting or the like, and also relates to a method of
casing a modified copper alloy using the same.
BACKGROUND ART
[0002] Since the grain refinement of a copper alloy is very
effective in improving 0.2% proof strength (a strength when
permanent distortion reaches 0.2%, hereinafter referred to as
simply `proof strength`) or the like, it is strongly desirable to
refine grains of a copper alloy. For example, the proof strength is
proportional to one over the square root of the grain size D
(D.sup.-1/2) according to the Hall-Petch theory (see E. O. Hall,
Proc. Phys. Soc. London. 64 (1951) 747. and N.J. Petch, J. Iron
Steel Inst. 174 (1953) 25.).
[0003] Basically, the grains of a copper alloy have been refined as
follows:
(A) the grains are refined during the melt-solidification of the
copper alloy, or (B) the grains are refined by processing or
heating the copper alloy (ingot such as slurry or the like; casting
including die casting or the like; and hot forged parts or the
like), in which stacking energy such as distortion energy or the
like acts as a driving force.
[0004] As methods of refining the grains like (A) in the prior art,
(a) to (d) have been proposed.
[0005] (a) Crystallized substances or the like are made to act as
crystal nuclei by adding grain refining elements such as Ti, Zr or
the like (Introduction of effective heterogeneous nuclei) (for
example, see Patent document 1).
[0006] (b) Homogeneous nuclei are generated by pouring a molten
alloy within an extremely narrow temperature range and thus
subjecting the molten alloy to super-cooling.
[0007] (c) Facilitating the generation of crystal nuclei or cutting
the arms of grown dendrites (tree-like crystal) by using an
electromagnetic induction agitator or steering (a device for
stirring the molten alloy); usually combined with method (b).
[0008] (d) Rapid solidification technique by die casting or the
like or solidifying a casting locally and rapidly by using a
chilling block.
[0009] In the above methods, the molten alloy is solidified before
the dendrites are grown, whereby the grains are refined.
[0010] In addition, as the methods of refining the grains after
casting like (B) in the prior art,
[0011] (e) Part of distortion energy provided by adequate processes
(rolling, drawing, forging or the like) on a melt-solidified alloy
material such as ingot or the like is accumulated in a metal, and
the energy accumulation brings the increase in re-crystallization
nuclei, whereby the grains are refined by using the energy as a
driving force (see Patent document 2).
[0012] (f) Melt-solidified alloy material such as ingot or the like
is provided with proper distortion energy and then heated, whereby
the accumulated energy released by the heating leads to
re-crystallization.
[0013] Patent document 1: JP-A-2004-100041
[0014] Patent document 2: JP-A-2002-356728
[0015] However, in the method (a), a large amount of the grain
refining elements should be used, and the large amount of the grain
refining elements can have an adverse influence on the inherent
features of a copper alloy. That is, even though the components of
the copper alloy are selected and determined to make the copper
alloy have the features suitable for the usage or the like, when
the grains of the copper alloy composed of the above-mentioned
components (hereinafter referred to as `copper alloy to be
modified`) are refined by method (a) in order to produce a
grain-refined copper alloy (referred to as `modified copper
alloy`), the adverse influence of the large amount of the grain
refining elements on the inherent features of the copper alloy to
be modified is bigger than the feature-improving effect or
feature-enhancing effect obtained by the grain refinement of the
copper alloy to be modified, whereby the features of the modified
copper alloy cannot be improved or enhanced as a whole.
[0016] In addition, since both methods (b) and (c) take a large
space or long time, the methods are not suitable for a small and
complex-shaped casting as well as a large-scaled and great quantity
of ingots, which are formed in a predetermined shape by a
continuous operation. Furthermore, the grains cannot be refined by
the methods as effectively as the above problems can be ignored,
whereby the methods have few industrial merits. Still furthermore,
a method of (d) has the following problem: that is, the rapid
solidification technique such as die casting or the like can be
applied to a limited range of solidified shapes or producing
procedures, and the rapid solidification technique using a chilling
block solidifies a casting locally, whereby the technique can be
installed to limited places and refine the grains to a low
degree.
[0017] Still furthermore, in methods (e) and (f), which are
basically different from methods (a) to (d), in which the grains
are refined during the melt-solidification, the grains are refined
by providing energy to an alloy after the melt-solidification, and
a machine for providing energy (for example, rolling machine,
drawing machine or forging machine) is required, whereby energy or
initial and running cost for the grain refinement would rise
significantly.
[0018] It is an advantage of an aspect of the invention to provide
a method of casting a modified copper alloy capable of refining
grains during the melt-solidification of the copper alloy without
the problems in the related art being induced.
DISCLOSURE OF THE INVENTION
[0019] Grains can be refined during the melt-solidification of an
alloy when primary crystals are generated from a molten liquid much
faster than the growth of dendrite crystals. After passionate
investigations, the present inventors found out that when an
extremely small amount of Zr is added to a copper alloy in the
presence of P and the ratio of P/Zr is in a proper range, the
generation of alpha phases, primary crystals, is facilitated
considerably, whereby the grains are refined remarkably during the
melt-solidification. In addition, it is found that when peritectic
or eutectic reaction occurs during solidification and beta phases
are crystallized around the primary alpha phases, the grains are
further refined. Furthermore, it is also found that when the beta
phases are transformed into kappa, gamma, delta, and mu-phases in
the alpha phase matrix by the reaction in solid phases, the grains
are much further refined.
[0020] However, Zr is an active and high melting point metal,
whereby it is difficult to control the amount of Zr in a narrow
range. In addition, even when the predetermined amount of Zr is
added to a copper alloy, if Zr in the copper alloy is oxidized or
sulphurized, such oxidized or sulfurized Zr cannot make any
contribution to the grain refinement. On the other hand, when a
large amount of Zr is added, the effect of Zr to refine the grains
is saturated, and further, Zr does not contribute to the grain
refinement, whereby the grain size increases, and the features such
as electric. thermal conductivities or the like deteriorate.
Furthermore, copper alloy members containing a large amount of Zr
can generate a great amount of oxide and sulfide according to the
melting atmosphere and the type or state of raw materials when they
are re-melted for recycling (various manufacturing processes
(material--commercialization), disposed products or the like),
whereby high quality castings cannot be made.
[0021] Still furthermore, even though the amount of Zr can be
controlled in an extremely narrow range with relative easiness if
non-contaminated materials are melted in a melting furnace having
special equipment or the like that makes non-oxidation atmosphere
and vacuum, such special equipment is expensive, and a great amount
of energy and time must be consumed in order to use the equipment.
Still furthermore, it is also found that the way of adding Zr needs
to be studied in order for a base material to contain the minimum
necessary amount of Zr, which can refine the grains even when the
alloy is cast at an end user level.
[0022] After passionate investigations, the inventors found out a
casting method, through which Zr can remain in a molten liquid
without being oxidized nor sulfurized, even when the furnace having
a special equipment or the like is not used. That is, the inventors
found out that Zr needs to be added in the form of Cu--Zn--Zr or
Cu--Zn--P--Zr master alloy so that it can remain in the molten
alloy without being oxidized nor sulphurized in order to refine the
grains, while, in general, Zr is added to a molten copper alloy in
the form of Cu--Zr.
[0023] That is, the invention provides a master alloy comprising
Cu: 40 to 80 wt. %, Zr: 0.5 to 35 wt. % and the balance of Zn, or a
master alloy comprising Cu: 40 to 80 wt. %, Zr: 0.5 to 35 wt. %, P:
0.01 to 3 wt. %, and the balance of Zn, both of which are used for
casting a copper alloy.
[0024] It is preferable that the master alloys according to the
invention further contain one element selected from the group
consisting of Mg: 0.01 to 1 wt. %, Al: 0.01 to 5 wt. %, Sn: 0.1 to
5 wt. %, B: 0.01 to 0.5 wt. %, Mn: 0.01 to 5 wt. % and Si: 0.01 to
1 wt. %. Particularly, it is more preferable that Cu occupy 50 to
65 wt. % and Zr occupy 1 to 10 wt. % in the master alloys since the
master alloys have a low-melting point and can be rapidly melted
into a molten alloy. (In the present specification, it should be
understood that "%" means "wt. %".) When a master alloy of the
invention is used, metal Zr as well as P can exist in the molten
alloy during solidification without influence of oxidation or
sulfurization even when a small amount of Zr is added. Accordingly,
primary alpha phases are crystallized and grains are easily
refined.
[0025] According to the invention, when manufacturing a copper
alloy by casting molten copper alloy containing Zr and P, it is
possible to cast a modified copper alloy by adding at least Zr in
the form of Cu--Zn--Zr or Cu--Zn--Zr--P master alloy. In the
above-mentioned casting methods according to the invention, a
concentration of metal Zr in the molten copper alloy, which is
required for grain refinement, is easily controlled in the range of
5 ppm or more and preferably 20 to 500 ppm. It is, therefore,
possible to efficiently crystallize primary alpha phases and to
efficiently refine grains.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a view showing a macro-structure of 76Cu-3Si-21Zn
casting, which is cast by using the master alloy of Sample No.
1(62Cu-3Zr-35Zn) in Table 1, observed by a magnifying glass of 7.5
times magnification;
[0027] FIG. 2 is a view showing the micro-structure of
76Cu-3Si-21Zn casting, which is cast by using the master alloy of
Sample No. 1 in Table 1, observed by a metallurgical
microscope;
[0028] FIG. 3 is a view showing the macro-structure of
76Cu-3Si-21Zn casting, which is cast by using the master alloy of
Sample No. 13 (50Cu-50Zr) in Table 1, observed by the magnifying
glass of 7.5 times magnification; and
[0029] FIG. 4 is a view showing the micro-structure of
76Cu-3Si-21Zn casting, which is cast by using the master alloy of
Sample No. 13 in Table 1, observed by the metallurgical
microscope.
BEST MODE FOR CARRYING OUT THE INVENTION
[0030] The invention provides a master alloy composed of Cu: 40 to
80%, Zr: 0.5 to 35%, and a remainder Zn; or Cu: 40 to 80%, Zr: 0.5
to 35%, P: 0.01 to 3%, and the remainder Zn. Hereinafter, the
reason why each component should be in a limited range will be
described.
Cu: Since the invention relates to a copper alloy master alloy, Cu
is a main element. However, the melting point does not decrease as
much as desired when Zr is added to pure Cu (melting point:
1083.degree. C.) (therefore, it will take a long time to melt the
master alloy: consequently, the effective amount of Zr decreases,
and the formation of zirconium oxide is facilitated in the alloy,
whereby Zr becomes totally ineffective). In addition, copper alone
cannot prevent the loss of Zr during the melting of the master
alloy and the formation of zirconium oxide in the alloy, therefore,
another additives are required to prevent the oxidation loss and
sulphurization loss of Zr and the formation of zirconium oxide in
the alloy. Furthermore, even when the other alloy element (Zn) is
added, if Cu occupies more than 80%, the above three problems
(melting point, the loss of Zr, the absence of effective Zr) cannot
be solved satisfactorily. However, when no Zn is contained in the
alloy to be modified, a master alloy used for such alloy must
consist of majority of Cu and minority of Zn, otherwise, the amount
of Zn in the modified alloy may exceed the limit allowed for
impurities.
[0031] Meanwhile, the reason why the minimum amount of Cu is
defined as 40% is that, when the amount of Cu does not reach 40%,
the melting point (liquidus line temperature) seldom decreases and,
conversely, high melting point zirconium oxide is generated. In
addition, when the amount of Cu decreases, that is, the amount of
the remainder Zn becomes excessive, too much Zn is evaporated and
thus the melting temperature does not decrease during the
manufacture of a master alloy, whereby it is difficult to
manufacture the master alloy.
Zr: Zr is an important element for grain refinement during the
solidification. The melting point (liquidus line temperature) of a
metal decreases when the metal is alloyed. That is, the melting
point of Zr is 1850.degree. C., and the melting point of Cu--Zr
intermediate alloy is in the range of 1000 to 1120.degree. C.
However, an average copper alloy has the liquidus line temperature
in the range of 870 to 1050.degree. C., the melting temperature in
the range of 950 to 1200.degree. C., and the pouring temperature in
the range of 890 to 1150.degree. C. The melting point of a master
alloy needs to be equal to or lower than the liquidus line
temperature of such copper alloy. In addition, the amount of Zr
begins to decrease as soon as Zr is melted in the oxidation
atmosphere. Therefore, if the melting takes a long time, the amount
of Zr cannot reach the predetermined amount. Therefore, it is
preferable that the melting point be as low as possible.
[0032] The minimum amount of Zr is defined as 0.5%, which is 100
times of the required amount 0.005%, in consideration of economic
burden, time and effort for charging Zr into a molten alloy or the
like. Even though it is preferable that the maximum amount of Zr be
as high as possible, the melting point of the alloy does not
decrease. The maximum amount of Zr is, therefore, defined as 35% in
order to make the melting point equal to or lower than the liquidus
line temperature. The amount of Zr is preferably in the range of 1
to 20%, more preferably in the range of 1 to 10%, and most
preferably in the range of 2 to 6%.
[0033] Zn: With the addition of Zn, a low melting point Zr--Zn--Cu
intermetallic compound can be formed, whereby the melting point of
such intermetallic compound is lowered than that of the matrix.
Next, a molten alloy contains oxygen, and some oxygen forms zinc
oxide before the oxygen forms zirconium oxide, whereby the amount
of oxygen in the molten alloy decreases so as to prevent Zr from
being oxidized and, consequently, to prevent the loss of Zr amount.
Therefore, it is preferable that the amount of Zn be larger than
that of Zr, depending also on the concentration of oxygen in the
molten alloy. It is more preferable that the amount of Zn be twice
or more than that of Zr, and most preferable that the amount of Zn
be three times or more than that of Zr. However, it is required to
adjust the amount of Zr and Zn properly on the basis of the amount
of Zn that can be contained as an impurity in a copper alloy to be
modified, such as Cu--Sn, which does not contain Zn as a necessary
element. Therefore, it is most preferable that the master alloy
contain 50 to 65% of Cu, 1 to 10% (2 to 6%) of Zr, and the
remainder Zn. In this case, the melting point reaches the lowest,
and, since more amount of Zn is contained than that of Zr in the
alloy, more amount of Zn is melted than that of Zr when Zr in the
master alloy is melted, whereby the oxidation loss of Zr and the
formation of zirconium oxide can be prevented.
[0034] P: P is an essential element. P can be added in a form of
Cu--P alloy as well as in a form of Cu--Zr--P--Zn master alloy. The
amount of P should be in the range of 7 to 20%, preferably 10 to
15% in the case of Cu--P alloy and 0.01 to 3% in the case of
Cu--Zr--P--Zn master alloy. However, the amount of P should be
adjusted to meet the following ratio of P/Zr at the
melt-solidification. Meanwhile, it is preferable that the
Cu--Zr--P--Zn master alloy contain, particularly, 50 to 65% of Cu
and 1 to 10% of Zr, since the melting point decreases, and the
master alloy can be melted into molten alloy quickly.
[0035] It is preferable that the master alloys according to the
invention further contain at least one element selected from the
group consisting of Mg: 0.01 to 1%, Al: 0.01 to 5%, Sn: 0.1 to 5%,
B: 0.01 to 0.5%, Mn: 0.01 to 5%, and Si: 0.01 to 1%.
[0036] These elements further lower the melting point of the Zr
intermetallic compound and the melting point of Cu--Zn matrix. In
addition, the elements prevent the oxidation. sulphurization loss
of Zr. Mg, Mn and Al prevent the sulphurization loss. The reason
why the elements should be in the limited range is as follows: the
minimum amount is the necessary amount to prevent the oxidation
loss of Zr, and conversely, over the maximum amount raises the
melting point, whereby no better effect can be found even when the
element is added more than necessary.
[0037] Meanwhile, if 0.005 mass % or more of Mg is contained in a
molten alloy before charging Zr, the component S in the molten
alloy is removed or fixed in the form of MgS. However, if the
excessive amount of Mg is added to a molten alloy, Mg is oxidized
like Zr, whereby casting defects such as oxide inclusion or the
like happen. Mn also removes the component S, even though not as
much as Mg. Sn refines the grains remarkably in the presence of Zr
and P, even though Sn alone can refine the grains to a small
degree. Sn improves mechanical properties (strength or the like),
corrosion resistance, and wear resistance, and works to cut
dendrite arms, whereby the grains are granulated and refined.
However, Sn carries out such functions even more remarkably when Zn
exists. In addition, gamma phases generated by the addition of Sn
suppress the grain growth after the melt-solidification and thus
contribute to the grain refinement. However, a high melting point
Zr--Sn--Cu intermetallic compound, the melting point of which
exceeds 1000.degree. C., is likely to be formed when the amount of
Sn exceeds 5%. Accordingly, it is preferable that the amount of Sn
be smaller than that of Zn. Al improves the flowability of a molten
alloy and prevents the oxidation/sulphurization loss of Zr, whereby
Al contributes remarkably to the grain refinement in casting
process when added with Zr and P. Furthermore, Al works to cut the
dendrite arms, like Sn, so as to granulate the grains, and improves
the strength, wear resistance or the like of the alloy.
[0038] Master alloys according to this invention can be
manufactured by the following method.
[0039] Pure Cu is melted in non-oxidation atmosphere, and then Zn
is added for deoxidation (First charge of Zn). In this case, the
concentration of Zn should be in the range of 3 to 25' in
consideration of the relationship with the temperature of the
molten alloy as well as in consideration of the relationship with
the vapor pressure of Zn. The temperature of the molten alloy is
raised up to 1100 to 1200.degree. C., and a predetermined amount of
a commercial master alloy Cu--Zr (Zr occupies 10 to 60%) is
charged. And, finally, a low melting point Zn is charged (Second
charge of Zn). Subsidiary components such as B and Mg (active
metals) are added at the same time as or after the second charge of
Zn. In the case of Sn, Al, Mn, Si (to be added in the form of pure
Si or Cu-15 Si), and P (to be added in the form of Cu-15 P), it is
preferable that a predetermined amount be added after the first
charge of Zn or at the same time as or after the second charge of
Zn.
[0040] The above intermediate alloys are poured in the shape of a
boat, a grain or the like, or manufactured by a continuous casting
in the shape of a rod or a wire. Alternatively, the intermediate
alloys are once manufactured into a large-sized casting, and then
the large-sized casting is formed into wire, rod, plate, or thin
plate by hot extrusion or hot rolling.
[0041] When such master alloys are charged into a melting furnace,
a holding furnace, a tundish or the like simultaneously or
continuously, a predetermined concentration of Zr can be secured in
the molten copper alloy with the presence of a predetermined
concentration of P.
[0042] (Manufacturing a Rod, a Wire, a Hollow Bar, and a
Large-Sized Ingot by Continuous Casting)
[0043] Basically, components other than Zr are added within a
predetermined composition range of an alloy. In consideration of
raw material conditions (such as raw materials being contaminated
with oil etc.), desulphurization and deoxidation additives such as
Mg, Sn, Al, Mn, and Si are further added within the effective
component range (or equal to or less than the concentration of
impurities), and then desulphurization and deoxidation are carried
out for confirmation. Generally, the melting furnace, gutter,
tundish, distributor are coated with charcoal in order to block
themselves from the air. Meanwhile, in the case of the
grain-refining element P, it is preferable that the shortfall of P
be replenished by charging Cu--P alloy (generally, P occupies 10 to
15%) into the melting furnace.
[0044] There are two methods for adding Zr, as described below. The
concentration of Zr and what subsidiary components to be contained
in a Zr master alloy are determined on the basis of the features of
the alloy to be modified (melting point, additives or the
like).
[0045] First of all, a master alloy is charged into the melting
furnace in order to make the alloy contain the predetermined amount
of Zr. And then, a casting such as ingot, billet etc. is cast.
Meanwhile, it takes a long time to complete the whole casting
process (semi-continuous casting), whereby the oxidation loss of Zr
happens in the melting furnace or the like. In order to replenish
the shortfall of Zr, master alloys in the form of several to 20
millimeter-large grains or wire or rod are further charged
continuously or at regular intervals to the tundish and the
distributor prior to the pouring. In this case, the melting point
of the master alloy must be lower than the pouring temperature of
the alloy. In the case where the master alloy can be melted
completely in the tundish and the distributor within one minute
without stirring, Zr can be precisely added by measuring the
melting loss of Zr during the casting beforehand.
[0046] In the other method, after the deoxidation and
desulphurization and the addition of P, the molten alloy is flowed
into the tundish or the distributor, and, there, a master alloy is
added in order to make the alloy contain a predetermined
concentration of Zr. While casting continuously, master alloys in
the form of several to 20 millimeter-large granular, wire or rod
are continuously charged into the tundish or the distributor. When
50 ppm of Zr is required, a master alloy containing 5% of Zr
occupies at most 1/1000 of the required amount of Zr, whereby no
problem happens during the casting. In case of the addition of a
master alloy to the tundish or the distributor, it is preferable
that the amount of Zr corresponding to the loss amount, say 1 to
40% of extra Zr, be added.
[0047] Meanwhile, when the components are added continuously, the
top priority is to melt the components quickly (the second priority
is not to oxidize the components), whereby it is preferable that a
master alloy contain 1 to 10% of Zr and have the concentration of
Cu in the range of 50 to 65%. Furthermore, it is preferable that a
master alloy contain elements that can lower the melting point of
each alloy system. Meanwhile, when the components are added into
the melting furnace, it is important to melt the components
quickly, however, it is also important that Zr does not form
oxidation and/or sulphurization in order to keep the loss of Zr
minimum.
[0048] (In the Case of Low-Pressure Casting, Die Casting, Molten
Alloy Forging (Metal Fittings for Water Supply, Water Meters or the
Like))
[0049] In the above-mentioned casting methods, a melting furnace is
highly airtight, whereby it is common that raw materials are
charged into the melting furnace little by little as may be
necessary during the casting in order to replenish the reduced
amount of molten alloy for the manufacturing of a casting. In
addition, when all raw materials are charged simultaneously, the
temperature of the melting furnace decreases, and thus the casting
temperature also decreases, therefore, in general, raw materials
are not charged simultaneously during operation time, but charged
at the intervals of operations such as early in the morning, during
lunch time, and late at night. That is, generally, a small amount
of raw materials is charged to stabilize the molten temperature as
much as possible. The above continuous operation can be carried out
by, largely, two methods.
[0050] The first method is to charge raw materials containing no Zr
and a master alloy in order to make the amount of Zr reach a
predetermined value. In this case, the master alloy is prepared in
a granular form, or by cutting the master alloy in the form of rod,
wire, boat or the like into a certain length. In addition, process
scrap and defective products in runners, which are sequentially
generated, and which oxidation or sulphurization is rarely
generated therein, are positively used in the continuous operation.
In this case, the master alloy is added in consideration of the
amount of Zr contained in the scraps. Meanwhile, when disposed
products or the like are used as raw materials, the disposed
products are used at the intervals between operations and, in this
case, Zr master alloy is added after the molten alloy is oxidized
and sulphurized sufficiently by Mg, Al or the like.
[0051] The other method is to charge ingots containing a
predetermined amount of Zr at regular intervals (in consideration
of the loss amount of Zr).
[0052] (In the Case of a Batch-Type Casting Such as Sand Casting
Etc.)
[0053] Since the components are melted simultaneously in a large
melting furnace, basically, the process is identical to the
above-mentioned process. What is different is that, while a
continuous casting is adopted in the above-mentioned process, a
batch-type casting is adopted in this case. In sand casting, it is
normal that the molten alloy is ladled and then poured into a sand
molding. The difference is that a sufficiently oxidized and
sulphurized molten master alloy is charged into the melting furnace
in case of continuous casting, while a master alloy is charged into
the ladle in case of sand casting.
[0054] The casting methods of the invention are useful for
preparing a copper alloy, wherein a small amount of Zr is added in
the presence of P; firstly primary alpha phases are crystallized;
secondarily peritectic or eutectic reaction occurs during
solidification; and then the grains are refined. Specifically, such
copper alloy includes Cu--Zn, Cu--Zn--Si, Cu--Zn--Sn, Cu--Zn--Al,
Cu--Zn--Pb, Cu--Zn--Bi, Cu--Zn--Si--Mn, Cu--Zn--Si--Pb,
Cu--Zn--Si--Sn, Cu--Zn--Si--Al, Cu--Zn--Sn--Pb, Cu--Zn--Sn--Bi,
Cu--Zn--Sn--Al, Cu--Sn, Cu--Sn--Pb, Cu--Sn--Bi, Cu--Al, Cu--Al--Si,
Cu--Si, Cu--Cr, Cu--Pb, Cu--P, and Cu--Te. Master alloys in Table 4
are used for each copper alloy after the composition ratios of the
master alloys are adjusted in the above-mentioned ranges.
Particularly, when such master alloys are used, it is required to
prevent the loss of the master alloy (the loss of effective Zr
contained in the master alloy) with cares on the followings: 1) the
molten alloy is deoxidized and desulphurized beforehand and 2) the
melting temperature and the casting temperature is in the
appropriate range.
[0055] For the above-mentioned copper alloys, it is preferable that
a small amount of Zr, that is, 5 ppm or more, preferably, 20 to 500
ppm Zr be added in the presence of P, preferably, 0.01 to 0.35 mass
% P.
[0056] Zr, like other additives, can refine the grains of a copper
alloy slightly by itself; however, Zr can refine the grains
remarkably in the presence of P. Even though Zr can refine the
grains at the amount of 5 ppm or more, the grains can be refined
remarkably when 10 ppm or more of Zr is added, and further
remarkably when 20 ppm or more of Zr is added. Therefore, the
amount of Zr should be 5 ppm or more, preferably 10 ppm or more,
and more preferably 20 ppm or more. However, the minimum amount of
Zr, at which the grains are refined by Zr in the presence of P,
considerably depends on the composition of matrix. For example, for
Cu--Sn alloy, Cu--Sn--Zn alloy, Cu--Sn--Zn--Pb alloy,
Cu--Sn--Zn--Bi alloy, Cu--Si alloy, Cu--Si--Zn alloy, Cu--Zn alloy,
Cu--Zn--(Bi, Pb) alloy, Cu--Al alloy, Cu--Zn--Al alloy,
Cu--Zn--Al--Sn alloy, Cu--Zn--Al--Sn--(Bi, Pb) alloy and
Cu--Zn--Al--(Bi, Pb) alloy, the grains are refined effectively even
when the amount of Zr is 5 ppm. However, for the copper alloys
having the composition close to pure Cu (for example, copper alloys
satisfying
[Zn]+3.times.[Sn]+5.times.[Si]+3.times.[Al]+0.5.times.[Bi]+0.5.times.[Pb]-
<15), it is preferable that the amount of Zr should be 50 ppm or
more in order to refine the grains effectively.
[0057] On the other hand, if the amount of Zr exceeds 0.3 mass %,
the grain refining function of Zr is saturated regardless of the
types or amounts of the other components. Meanwhile, since Zr has
an extremely strong affinity to oxygen, when an alloy is melted in
the air or scrap materials are used as raw materials, Zr is likely
to become oxide or sulfide. Accordingly, if Zr is added
excessively, the oxide or sulfide is included during the casting.
In order to avoid such problem, it can be considered to melt and
cast the alloy under vacuum or completely inactive gas atmosphere.
However, in this case, the casting method will lose its general
versatility and consequently, the casting cost rises drastically
for a modified copper alloy, to which Zr is added only as a grain
refining element. Considering the above problem, to modify a copper
alloy according to this invention, the amount of Zr, which is not
formed in the form of oxide or sulfide, should be 500 ppm or less,
preferably 300 ppm or less, and optimally 200 ppm or less.
[0058] In addition, if the amount of Zr is in the above range, even
when the modified copper alloy is melted in the air as a recycled
material, the amount of zirconium oxide or zirconium sulfide
generated during the melting is reduced, and robust modified copper
alloy can be obtained. Furthermore, it is possible to easily
transform the modified copper alloy into a copper alloy to be
modified.
[0059] In addition, from a view point of casting products, it is
preferable to add Zr, which is not oxidized or sulphurized, in the
form of granular substance or thin plate-like substance, or as an
intermediate alloy in such forms as granular or thin plate-like
right before the pouring during the casting. That is, as described
above, since Zr is an easily oxidized element, it is preferable to
add Zr right before the pouring during the casting. However, in
this case, since the melting point of Zr is higher than that of a
copper alloy by 800 to 1000.degree. C., it is preferable to add Zr
as granular substance (grain diameter: about 2 to 50 mm), thin
plate substance (thickness: about 1 to 10 mm) or); or a low melting
point master alloy in the granular form or thin plate-like form
having the melting point close to that of the copper alloy and
containing a great amount of necessary elements.
[0060] Meanwhile, like Zr, P itself can refine the grains of a cast
alloy slightly, however, P can refine the grains remarkably in the
presence of Zr, or Zr and Si. That is, even though 100 ppm (0.01
mass %) or more of P can refine the grains, at least 300 ppm or
more of P is required to refine the grains remarkably when no Si is
added, however, only 200 ppm or more of P can refine the grains
remarkably when Si is added. In addition, if 300 ppm or more of P
is contained when Si is added, the grains can be refined further
remarkably.
[0061] On the other hand, if the amount of P exceeds 0.35 masse,
the grain refining function of P is saturated. In order to
effectively refine the grains without negative influence on the
inherent features of an alloy in the casting method, in which P is
added as a grain refining element, it is preferable that the amount
of P be 0.25 mass % or less, more preferably 0.2 mass % or less,
and optimally 0.15 mass %.
[0062] Meanwhile, it can be considered that an intermetallic
compound of Zr and P may play a role in the grain refinement
process, and the amount ratio of P/Zr should satisfy
0.5<P/Zr<150, preferably 1<P/Zr<50, and optically
1.2<P/Zr<25. By limiting the amount ratio of P/Zr in the
above range, the primary alpha phases can be crystallized during
the solidification, and then beta phases can be crystallized by
peritectic or eutectic reaction. Accordingly, the grains can be
refined.
[0063] Since the invention relates to the methods of refining
grains during the casting process, it is possible to improve the
hot workability of a copper alloy, and thus to perform the
processing work such as rolling, forging, extruding, drawing or the
like satisfactorily after casting.
[0064] According to the invention, the casting methods (wherein
casting products, ingot, slab or the like are obtained by 1) sand
casting, 2) permanent mold casting, 3) low-pressure casting, 4)
continuous casting, 5) die casting, 6) squeeze, 7) lost wax casting
8) semi-solid (semi-solid metal solidifying method), 9) molten
alloy forging) can achieve the strength improvement (comparing to a
copper alloy to be modified, the strength and the proof strength
are improved by 10 to 20% or more, and the elongation or the like
is improved to the same or more degree), brittleness reduction,
wall thickness reduction, weight lightening, toughness improvement,
impact characteristic improvement, ductility improvement, casting
defect (porosity, shrinkage cavity, hole, crack- or the like)
reduction or the like of copper alloy casting products. Therefore,
it is possible to obtain high quality casting products including
complex shaped products, extremely large-sized and small-sized
products.
[0065] In addition, according to the invention, since the casting
methods provide castings (casting products), particularly produced
by permanent mold casting or continuous casting, which have the
same degree of grain size and strength as those of hot extruding
material or drawing material of a copper alloy to be modified, the
castings according to the present invention can replace the
extruding material and the drawing material (or forging material
made of the hot extruding material or the drawing material). The
castings according to the present invention need not to be
subjected to the working processes such as extrusion or the like,
whereby the manufacturing cost can be reduced considerably, and the
energy can be saved.
[0066] In order to effectively refine the grains during the
melt-solidification in any casting methods, it is preferable that
the primary crystal be alpha phases during the melt-solidification,
and that beta phases occupy 95% or less in the total phase
structure right after the melt-solidification and also 50% or less
at the room temperature after the melt-solidification. It is more
preferable that beta phases occupy 20% or less in the total phase
structure at the room temperature and beta phases be transformed
into alpha, kappa, gamma, delta, and mu-phases. Furthermore, if an
adequate amount of predetermined phases (one to three phases among
beta, kappa, gamma, and delta phases) exist at a high temperature
right after the melt-solidification, the beta, kappa and gamma
phases suppress the growth of alpha grains and thus the grains are
effectively refined. Therefore, it is preferable that beta, kappa,
gamma and delta phases occupy 5 to 95% of the surface ratio (total)
in the phase structure at the high temperature right after the
melt-solidification. It is also preferable that the phase diagram
include one to four phases selected from alpha, beta, kappa, gamma,
delta or mu phases at the room temperature after
melt-solidification. Meanwhile, kappa, gamma, delta and mu phases
existing at the room temperature after the melt-solidification have
no adverse influence on grain refinement. In addition, in the case
of a copper alloy containing Zn and Si, the above phases contribute
to the grain refinement, and, particularly, the grains are refined
remarkably when kappa and/or gamma phases exist abundantly.
Meanwhile, when a lot of beta phase exists (for example, when beta
phase occupies more than 10% of the surface ratio in the phase
diagram at the room temperature), even though the corrosion
resistance or ductility of the castings (permanent mold casting
products or the like) may deteriorate, such problems can be solved
by conducting an adequate heat treatment on the castings (for
example, heat treatment at 400 to 600.degree. C. for 10 minutes to
4 hours). That is, heat treatment can remove or divide beta phases.
The effect of the heat treatment to remove and divide beta phases
becomes more remarkable as the grain size becomes smaller.
[0067] In addition, in order to drastically refine the grains in
both macro-structure and micro-structure, it is preferable that the
forms of solid phases during the melt-solidification, or the grains
or alpha phases at the room temperature after the
melt-solidification be circular or substantially circular when
observed two-dimensionally, which is formed by cutting the dendrite
arms. That is, it is preferable that the two dimensional forms be
non-dendritic, circular, oval, cross-like, needle-like or
polygonal. Particularly, if the solid phases have the dendrite arms
spreading like a net within the castings (castings including ingot,
slab, die casting or the like, semi-solid metal forging products or
the like), the grains of which are strongly desired to be
substantially circular and small, otherwise, flowability of the
molten alloy deteriorates and substantial defects such as porosity,
shrinkage cavity, blowhole, casting crack or the like occur.
However, if the two dimensional forms are circular or substantially
circular and then the solid phases are granulated, flowability to
every corner is notably improved and thus high quality casting
products can be obtained. The improvement of flowability (molten
alloy flowability) is profitable and practically effective in the
semi-solid metal casting method or semi-solid metal forging method
performed in a semi-solid metal state (solid phase+liquid phase).
For example, it is not required to perform a grain refining
treatment (for example, steering, electromagnetic induction
agitation, hot working (hot extrusion, drawing or the like)) as a
pretreatment on materials used in the semi-solid metal forging
method (For this reason, it becomes preferable for, particularly,
thixo-casting). Furthermore, when the grains are small and
substantially circular, a casting having such grains shows a strong
resistance against the crack caused by thermal distortion or the
like during and right after the melt-solidification. In addition,
even when used as ingot, such castings have a great deformability.
Therefore, materials difficult to be hot worked can also be easily
obtained without crack.
[0068] Generally, except when a casing is rapidly solidified or
under special techniques such as the above electromagnetic
induction agitation or the like, the grain size of the casting
(melt-solidified copper alloy) is larger than that of the material
produced by post-casting treatment such as rolling or the like
applying distortion energy and is larger ten times or more thereof.
That is, grains should be refined as long as a great amount of
energy is consumed. Therefore, from a technical viewpoint, it is
inadequate to treat `castings with the grains refined during the
melt-solidification`, and `castings with the grains refined by
post-casting treatment like methods (e) and (f)` in the same
category. However, as understood from the following examples,
comparing to a copper alloy with the refined grains by extruding,
drawing or rolling, the grain size of a modified copper alloy of
the invention, the grains of which are refined during the casting
process, is almost equal, and the mechanical strength is also
almost equal or higher. It deserves attention that a casting,
produced simply by melting and solidifying a predetermined
composition, has the almost same mechanical strength as that of a
casting produced by consuming a great amount of energy through
rolling or the like.
[0069] Furthermore, in comparison with a copper alloy to be
modified, the proof strength of casting products of a modified
copper alloy (0.2% proof strength of ingot or the like after the
melt-solidification) is improved by 10% or more (preferably 20% or
more, more preferably 30% or more, and optically 40% or more)
through the grain refinement, when both alloys are cast under the
identical condition except for the grains being refined (in the
modified copper alloy) or not (in the copper alloy to be
modified).
[0070] (Manufacturing Master Alloys)
[0071] Master alloys disclosed in Tables 1 to 3 are manufactured by
the above-mentioned methods of manufacturing a master alloy.
[0072] In the following Table 1, 75 ppm Zr+0.06% P is added to
Alloy 1: 76Cu-3Si-21Zn alloy, and the optimal amount of Zr (which
is not in the form of oxide and sulfide) is defined as 25 to 75
ppm.
[0073] In the following Table 2, 100 ppm Zr+0.06% P is added to
Alloy 2: 73Cu-25.5Zn-1.5Sn alloy, and the optimal amount of Zr
(which is not in the form of oxide and sulfide) is defined as 40 to
100 ppm.
[0074] In the following Table 3, 200 ppm Zr+0.06% P is added to
Alloy 3: 90Cu+10Sn alloy, and the optimal amount of Zr (which is
not in the form of oxide and sulfide) is defined as 120 to 200
ppm.
EXAMPLE 1
[0075] Electrolytic Cu, electrolytic Zn, electrolytic Sn, and
Cu-15% Si alloy are melted in the descending order of melting
point, which is Cu, Cu-15' Si alloy, Zn and Sn, and then Cu-15P is
added so that the total mass reaches about 3 kilograms. The
temperature of the final molten alloy is set at approximately
100.degree. C. above the liquidus line temperature of each alloy
(that is, 970.degree. C. for Alloy 1, 1040.degree. C. for Alloy 2,
and 1120.degree. C. for Alloy 3). After 5-minute holding, Zr master
alloys disclosed in Tables 1 to 3 are added so that a predetermined
amount of Zr can be contained at the final stage. After 10-second
stirring by a graphite rod, the alloy is held for one minute, and
then again, is stirred by the graphite rod for about 5 seconds.
After that, the molten alloy is poured into a .phi.40.times.250(l)
or 35t.times.65w.times.200(l) sized metal mold.
[0076] Meanwhile, as a comparative example, a predetermined amount
of Cu-35Zr and Cu-50Zr alloys is added.
[0077] Furthermore, the holding time is extended for some
alloys.
[0078] Each of the master alloys is cut into a cube having sides of
about 5 mm, and then is cut again to contain a predetermined Zr
amount.
[0079] The pouring temperature is, generally, in the range of 30 to
150.degree. C. above the liquidus line temperature. If the pouring
temperature is too high, casting defects such as crack or the like
are likely to occur. The melting temperature is, generally,
50.degree. C. above the pouring temperature in consideration of the
temperature decrease in a runner or the like. An unreasonable rise
of temperature results in the waste of energy.
[0080] 40 mm-long pieces are cut off from the top and bottom of the
complete castings, and then the surfaces thereof are grinded. After
that, the macro-structure is developed by nitric acid, and then the
real scale and 7.5 times magnified grain size are measured by a
magnifying glass according to JIS comparative method.
[0081] FIG. 1 is a view showing the macro-structure of
76Cu-3Si-21Zn casting that is cast by using a master alloy of
Sample No. 1 (62Cu-3Zr-35Zn) in Table 1, the surface of which is
treated by nitric acid and then observed by a magnifying glass of
7.5 times magnification. FIG. 2 is a view showing the
micro-structure of 76Cu-3Si-21Zn casting that is cast by using the
master alloy of Sample No. 1 in Table 1, the surface of which is
treated by hydrogen peroxide and ammonia and then observed by a
metallurgical microscope. From FIG. 2, it can be understood that,
in the casting alloy, the grain size is 50 .mu.m or less and,
accordingly, the grains are refined.
[0082] Furthermore, FIG. 3 is a view showing the macro-structure of
76Cu-3Si-21Zn casting that is cast by using a master alloy of
Sample No. 13 (50Cu-50Zr) in Table 1, the surface of which is
treated by nitric acid and then observed by a magnifying glass of
7.5 times magnification. FIG. 4 is a view showing the
micro-structure of 76Cu-3Si-21Zn casting that is cast by using the
master alloy of Sample No. 13 in Table 1, the surface of which is
treated by hydrogen peroxide and ammonia and then observed by a
metallurgical microscope. The grain size in the casting products
manufactured by using this master alloy is 150 .mu.m.
TABLE-US-00001 TABLE 1 Master alloy (75 ppm Zr + 0.06% P) is added
to 76Cu--3Si--21Zn alloy Type of master alloys (%) Casting result
No. Cu Zr Zn Others Zr Grin size .mu.m Remark 1 62 3 35 0 69 50
.mu.m or less 2 61 0.9 38.1 0 71 50 .mu.m or less 3 58 6 36 0 68 50
.mu.m or less 4 76 3 21 0 67 50 .mu.m or less 5 44 31 25 0 60 50
.mu.m or less 6 55 12 33 0 65 50 .mu.m or less 7 60 4 35.5 Mg 0.5
71 50 .mu.m or less 8 58 6 34 Al 2 70 50 .mu.m or less 9 60 4 35.4
Si 0.6 71 50 .mu.m or less 10 60 4 35.7 B 0.3 71 50 .mu.m or less
11 57 6 35 Mn 2 68 50 .mu.m or less 12 55 4 40 P 1 70 50 .mu.m or
less 13 50 50 0 0 12 200 Part of master alloy not melted 14 50 50 0
0 32 150 Bottom: 100 .mu.m, Top: 200 .mu.m, Holding time: 3 min.
extended 15 65 35 0 0 15 150 Part of master alloy not melted 16 65
35 0 0 43 125 .mu.m or less Bottom: 50 .mu.m, Top: 200 .mu.m,
Holding time: 3 min. extended
TABLE-US-00002 TABLE 2 Master alloy (100 ppm Zr + 0.06% P) is added
to 73Cu--25.5Zn--1.5Sn alloy Type of master alloys (%) Casting
result No. Cu Zr Zn Others Zr Grin size .mu.m Remark 17 62 3 35 0
90 50 .mu.m or less 18 61 0.9 38.1 0 89 50 .mu.m or less 19 58 6 36
0 87 50 .mu.m or less 20 76 3 21 0 86 50 .mu.m or less 21 44 31 25
0 76 50 .mu.m or less 22 55 12 33 0 82 50 .mu.m or less 23 60 4
35.5 Mg 0.5 90 50 .mu.m or less 24 58 6 34 Al 2 92 50 .mu.m or less
25 60 4 33 Sn 3 89 50 .mu.m or less 26 57 6 35 Mn 2 90 50 .mu.m or
less 27 55 4 40 P 1 91 50 .mu.m or less 28 50 50 0 0 27 300 Part of
master alloy not melted 29 50 50 0 0 55 1000 Bottom: 500 .mu.m,
Top: 150 .mu.m, Holding time: 3 min. extended 30 50 50 0 0 53 275
Bottom: 150 .mu.m, Top: 400 .mu.m Holding time: 3 min. extended,
Second experiment 31 65 35 0 0 57 175 Bottom: 100 .mu.m, Top: 250
.mu.m
TABLE-US-00003 TABLE 3 Master alloy (200 ppm Zr + 0.06% P) is added
to 90Cu--10Sn alloy Type of master alloys (%) Casting result No. Cu
Zr Zn Others Zr Grin size .mu.m Remark 32 62 3 35 0 178 50 .mu.m or
less 33 61 0.9 38.1 0 182 50 .mu.m or less 34 58 6 36 0 173 50
.mu.m or less 35 76 3 21 0 176 50 .mu.m or less 36 44 31 25 0 157
50 .mu.m or less 37 55 12 33 0 166 50 .mu.m or less 38 60 4 35.5 Mg
0.5 176 50 .mu.m or less 39 58 6 34 Al 2 180 50 .mu.m or less 40 60
4 33 Sn 3 179 50 .mu.m or less 41 57 6 35 Mn 2 178 50 .mu.m or less
42 55 4 40 P 1 181 50 .mu.m or less 43 50 50 0 0 75 400 Part of
master alloy not melted 44 50 50 0 0 118 250 Bottom: 100 .mu.m,
Top: 400 .mu.m Second experiment 45 65 35 0 0 115 175 Bottom: 100
.mu.m, Top: 250 .mu.m
EXAMPLE 2
[0083] For each alloy system in Table 4, a specific composition of
an alloy is adjusted to make the copper alloy meet
60<Cu-3.5Si-1.8Al-0.5X+0.5Y+Mn<90 (wherein X is Sn, Sb, As,
Mg; Y is Pb, Bi, Se, Te, Cr; preferably in the range of 62 to 71,
and more preferably in the range of 63 to 67). In casting, typical
master alloys indicated in the rightmost column are adjusted in the
range of the invention and then added. In the same way as Example
1, 40 mm-long pieces are cut off from the top and bottom of the
casting and then the surfaces thereof are grinded. After that, the
macro-structure is developed by nitric acid, and then the real
scale and 7.5 times magnified grain size are measured by a
magnifying glass according to JIS comparative method. In any cases,
the grain size is 50 .mu.m or less.
TABLE-US-00004 TABLE 4 Typical composition of alloys to be modified
(grain refined) Alloy Typical master system Cu Zn Si Sn Al Pb Bi Mn
Cr P Te alloy Cu--Zn 70 remainder Cu--Zn--Zr, Cu--Zn--Zr--P,
Cu--Zn--Zr--B Cu--Zn--Si 76 remainder 3 Cu--Zn--Zr, Cu--Zn--Zr--P,
Cu--Zn--Zr--Si Cu--Zn--Si 79 remainder 3.8 Same as above **2
Cu--Zn--Sn 69.5 remainder 1.2 Cu--Zn--Zr, Cu--Zn--Zr--P,
Cu--Zn--Zr--Sn Cu--Zn--Sn 78 remainder 2.5 Same as above **2
Cu--Zn--Al 77 remainder 2 Cu--Zn--Zr, Cu--Zn--Zr--P, Cu--Zn--Zr--Al
Cu--Zn--Pb 63 remainder 1 Cu--Zn--Zr, Cu--Zn--Zr--P, Cu--Zn--Zr--Mg
Cu--Zn--Bi 63 remainder 1 Cu--Zn--Zr, Cu--Zn--Zr--P, Cu--Zn--Zr--Mg
Cu--Zn--Si--Mn 73 remainder 4 3 Cu--Zn--Zr, Cu--Zn--Zr--P,
Cu--Zn--Zr--Mn Cu--Zn--Si--Mn 64 remainder 1 3 Same as above **2
Cu--Zn--Si--Pb 76 remainder 3 0.1 Cu--Zn--Zr, Cu--Zn--Zr--P,
Cu--Zn--Zr--B Cu--Zn--Si--Sn 77 remainder 3 0.4 Cu--Zn--Zr,
Cu--Zn--Zr--P, Cu--Zn--Zr--Si Cu--Zn--Si--Sn 75 remainder 1.5 0.5
Same as above **2 Cu--Zn--Si--Al 77 remainder 3 0.5 Cu--Zn--Zr,
Cu--Zn--Zr--P, Cu--Zn--Zr--Al
TABLE-US-00005 TABLE 5 Cu--Zn--Sn--Pb 64 remainder 1.5 1
Cu--Zn--Zr, Cu--Zn--Zr--P, Cu--Zn--Zr--Sn Cu--Zn--Sn--Pb 84
remainder 5 4 Same as above **2 Cu--Zn--Sn--Bi 82 remainder 5 2
Cu--Zn--Zr, Cu--Zn--Zr--P, Cu--Zn--Zr--Sn Cu--Zn--Sn--Bi 63
remainder 1 1 Same as above **2 Cu--Zn--Sn--Al 74 remainder 1.5 0.5
Cu--Zn--Zr, Cu--Zn--Zr--P, Cu--Zn--Zr--Al Cu--Sn 90 10
Cu(high)-Zn--Zr, Cu--Zn--Zr--P, Cu(high)-Zn--Zr--Sn Cu--Sn--Pb 83 9
8 Cu(high)-Zn--Zr, Cu--Zn--Zr--P, Cu(high)-Zn--Zr--Sn Cu--Sn--Bi 89
6 5 Cu(high)-Zn--Zr, Cu--Zn--Zr--P, Cu(high)-Zn--Zr--Sn Cu--Al 92 8
Cu(high)-Zn--Zr, Cu--Zn--Zr--P, Cu--Zn--Zr--Al Cu--Al--Si 93 2 5
Cu(high)-Zn--Zr, Cu--Zn--Zr--P, Cu--Zn--Zr--Al Cu--Si 97 3
Cu(high)-Zn--Zr, Cu--Zn--Zr--P, Cu--Zn--Zr--Si Cu--Cr 99 1
Cu(high)-Zn--Zr, Cu--Zn--Zr--P, Cu--Zn--Zr--Mg Cu--P 99.8 0.2
Cu(high)-Zn--Zr, Cu--Zn--Zr--P, Cu--Zn--Zr--Mg Cu--Pb 99 1
Cu(high)-Zn--Zr, Cu--Zn--Zr--P, Cu--Zn--Zr--Mg Cu--Te 99.3 0.7
Cu(high)-Zn--Zr, Cu--Zn--Zr--P, Cu--Zn--Zr--Mg **means a case that
there are two typical compositions.
INDUSTRIAL APPLICABILITY
[0084] According to the methods of the invention for melting and
solidifying a copper alloy to be modified, grains of modified
copper alloy can be refined in continuous casting method,
semi-solid metal casting method, sand casting method, permanent
mold casting method, low-pressure casting method, die casting, lost
wax, up casting, squeeze, centrifugal casting method, welding,
lining, overlaying or build-up spraying.
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