JP3461081B2 - Copper alloy for mold casting excellent in corrosion resistance, method for producing the alloy, and faucet using the alloy - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper alloy for die casting which is excellent in corrosion resistance, particularly dezincification corrosion resistance, and is suitable for water supply and drainage fittings such as faucets and valves, and copper for die casting which is excellent in corrosion resistance. The present invention relates to an alloy, a method for producing the alloy, and a water faucet using the alloy.

[0002]

2. Description of the Related Art As a copper alloy having excellent corrosion resistance, Japanese Patent Publication No.
The weight ratio of Cu 58.0 to 6 is disclosed in JP-A 8-38500.
3.0%, Sb 0.02 to 0.5%, Pb 0.5 to 3.
0%, Sn 0.2 to 1.0%, Fe 0.1 to 0.5%,
A special dezincification-corrosion-resistant special brass consisting of the balance Zn and inevitable impurities is disclosed. In addition, bronze casting (JIS B
C6 (see Table 1) also has excellent corrosion resistance. Furthermore, the brass castings used for casting are JIS YBsC3
(See Table 1).

[0003]

When an alloy having a composition similar to that of the conventional alloy (Table 4) was subjected to die casting, casting cracks occurred. The reason is that when Sn is 0.2% by weight or more and the zinc equivalent is smaller than 35.7% by weight, the solidification temperature range exceeds 17 ° C and shrinkage occurs when the molten metal is cooled and solidifies on the mold surface. Since the solidification temperature range is wide with respect to the cracks of the generated solid, the layer of the mixture of the solid and the liquid in contact with the solid becomes thick, so that the flow of molten metal becomes poor and the liquid becomes difficult to be supplied to the crack of the solid. As a result, cracks remain on the surface of the casting. When die casting was also performed on JIS BC6, casting cracks also occurred. However, when the solidification temperature range is small, since the mixture of the solid and the liquid is thin, the flow of hot water is good, and the liquid is supplied to the cracks of the solid caused by the solidification shrinkage,
No cracks on the surface of the casting.

Although JIS YBsC1 to 3 are for castings, they are not excellent in corrosion resistance.

Therefore, the present invention provides a copper alloy for die casting which is excellent in die casting property and corrosion resistance, a manufacturing method for improving the corrosion resistance of the alloy, and a water faucet excellent in corrosion resistance.

[0006]

A die casting alloy according to the present invention is a copper alloy having two phases, an α phase and a β phase,
Composition is Sn, Sb, As, P, Pb, Al, Fe, Z
In the die casting alloys of n and Cu, each of the above groups
The compounding ratio of the components is Sn 0.05 to 0.2% by weight, Sb,
Any one or more of As and P is 0.05 to 0.
3% by weight, Zn = 1, Sn = 2, Pb = 1, Al = 6,
Solidification in which the zinc equivalent calculated from the Guillet coefficient of Fe = 0.9 is 35.7 to 41.0% by weight, the balance is Cu, and the β phase area occupation ratio is 15% or less. The temperature range is 17 ° C. or less. The die casting alloy contains Zn 33.0 to 37.0 wt% and Pb.
0.5 to 3.0 wt% and Al 0.1 to 0.5 wt% can be contained. Further, the alloy for die casting of the present invention
Is a copper alloy consisting of two phases, α phase and β phase.
The composition is Sn, Sb, As, P, Pb, Al, F
In the copper alloy for die casting, which is e, Zn, and Cu,
The compounding ratio of each composition is Sn 0.05 to 0.2% by weight,
Any one or more of Sb, As or P 0.05
~ 0.3 wt%, Zn = 1, Sn = 2, Pb = 1, Al
= 6, Fe = 0.9 calculated by Guillet's coefficient
Zinc equivalent is 35.7 to 41.0% by weight, the balance is C
After casting the copper alloy consisting of u
Hold it for at least 3 minutes and within 3 hours to increase the β phase area occupation ratio to 15
% Or less.

[0007]

[0008]

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The copper alloy of the present invention has a Sn content of 0.2.
The amount of Sb, As, and P is 0.05 to 0 in order to improve mold castability by adjusting the weight ratio to 1% or less, the zinc equivalent to 35.7% by weight or more, and the Al content to 0.1% by weight or more as necessary. 0.3% by weight, zinc equivalent 41.0% by weight or less, Z as necessary
Excellent corrosion resistance can be obtained by setting n to 37% by weight or less and by reducing the area occupancy ratio of the β phase by heat treatment after casting.

The action and composition range of the additional alloying elements in the copper alloy of the present invention will be described. 1) Sn 0.05 to 0.2 wt% In order to improve the corrosion resistance, 0.05 wt% or more is added, but in the mold casting, Sn which functions to expand the solidification temperature range exceeds 0.2 wt%. And the solidification temperature range is 17 °
Since C exceeds C and casting cracks frequently occur, Sn is suppressed to 0.2% by weight or less in order to prevent the solidification temperature range from exceeding 17 ° C as shown in FIG. As for machinability, there is no problem in yield even if machined with a component of 0.2% by weight or less.

2) Any one or more of Sb, As and P 0.05 to 0.3 wt% In order to improve the corrosion resistance, 0.05 wt% or more is added, but 0.3 wt% Since corrosion resistance does not remarkably improve even if the content exceeds the above range, it was set to 0.3% by weight or less in consideration of economic efficiency. It should be noted that, instead of Sb, As or P having the same action as Sb
May be added, or these may be added in combination.

3) Zn 33.0 to 37.0 wt% 33.0 wt% or more is added in consideration of the casting yield, but when it exceeds 37.0 wt%, as shown in Table 3,
The β-phase region, which is inferior in corrosion resistance, increases and the dezincification corrosion resistance decreases, so the content is made 37.0% by weight or less.

4) 0.1 to 0.5% by weight of Al 0.1% by weight or more is added to improve the castability, but if it exceeds 0.5% by weight, elongation and impact value decrease. , 0.5 wt% or less.

5) Zinc equivalent 35.7-41.0% by weight The zinc equivalent of the present invention is the well-known Guillet zinc equivalent, and the coefficients are Zn = 1, Ni = -1.3, Fe =
0.9, Pb = 1, Mg = 2, Sn = 2, Al = 6, S
i = 10.

As a result of investigating the relationship between the zinc equivalent and the corrosion depth, as shown in FIG. 3, the heat-treated copper alloy has higher corrosion resistance as the zinc equivalent is smaller, the zinc equivalent is larger, and the copper alloy is not heat treated. The maximum corrosion depth in the JBMA test is 200 μm, and the maximum corrosion depth becomes larger than that of the copper alloy without heat treatment when the zinc equivalent is further increased. Therefore, the maximum corrosion depth is set to 200 μm or less at which the effect of improving the corrosion resistance due to heat treatment is lost.
That is, the zinc equivalent was within the range of 41.0% by weight or less. Next, when the relationship between the zinc equivalent and the solidification temperature range was examined, as is clear from FIG. 4, the larger the zinc equivalent, the smaller the solidification temperature range. As mentioned above, the solidification temperature range is 17
When the temperature exceeds ° C, casting cracks frequently occur, so the solidification temperature range is 17 ° C or less, and therefore, the zinc equivalent is 35.7% by weight or more as the allowable range.

6) Pb 0.5 to 3.0% by weight It is a well-known additive element for improving the machinability, and in the present invention, 0.5% by weight or more is added, if necessary. If it exceeds 3.0% by weight, the elongation and the impact value decrease, so the content is made 3.0% by weight or less.

7) The inevitable impurities such as the impurity Fe are suppressed as much as possible to reduce their influence.

Next, the heat treatment will be described. The component composition of the copper alloy of the present invention exhibits an α + β two-phase structure in the as-cast state, and since the amount of Sn added is small, the dezincification resistance of the β phase is poor and the corrosion resistance is not excellent. As shown in FIG. 1, when the relationship between the area occupancy ratio of the β phase and the corrosion depth was examined, it was found that the smaller the area occupancy ratio of the β phase, the higher the corrosion resistance. Therefore, the range of the area occupancy ratio of the β phase in which the corrosion resistance is allowed is the maximum corrosion of 200 μm or less in the JBMA test as described above, and therefore, the corresponding β
The area occupancy ratio of the phase was set to 15% or less as the upper limit of tolerance.

Since conventional materials and die casting methods do not have the corrosion resistance required for faucets, pressure resistant parts such as the primary pressure side cannot withstand corrosion with brass. The water resistant metal fittings were molded and the non-pressure resistant parts were molded by die casting. However, in sand mold casting, dust and the like are harmful to the human body, and therefore there is a problem that it is expensive to take measures against dust. In addition, there is a problem that the surface treatment of the faucet appearance such as polishing is expensive and the cost is increased. However, with the material and the manufacturing method of the present invention, the die casting can be used for the pressure resistant portion, and the above problem can be solved. Conventionally, the life of a faucet is usually about 10 years. Therefore, when the copper alloy of the present invention is used for a pressure resistant part of a faucet, in order to satisfy the above-mentioned durability, in consideration of corrosion resistance, β-phase The area occupation ratio should be 8% or less.

In the copper alloy of the present invention, the β phase region is reduced by the heat treatment at 450 to 550 ° C.
As the Sb concentration increases, the β phase dramatically increases the corrosion resistance.

When the heat treatment temperature exceeds 550 ° C., the β-phase region tends to increase and the corrosion resistance deteriorates to 450 ° C.
If it is less than C, it takes a long time to eliminate the localized uneven distribution of elements existing in the grain boundaries and to reduce the β phase region, so that 450 to 5
50 ° C is desirable.

If the heat treatment time is less than 30 minutes, the effect of decreasing the β phase does not appear, so it is desirable to hold the heat treatment for 30 minutes or more, but 3 hours or less is sufficient, and if it exceeds 3 hours, the heat treatment effect is not so much. Therefore, it is set to 30 minutes or more and 3 hours or less in consideration of economy.

[0023]

EXAMPLES Specific examples of the present invention will be described. Copper alloys having the compositions shown in Table 1 were manufactured by a known melting method, and the alloys of the present invention were held at 500 ° C for 3 hours.
In this example, Pb was added to improve machinability.

The results of the dezincification corrosion test conducted on the copper alloy are shown in Table 2. The copper alloy of the present invention is
It can be seen that zinc corrosion resistance is superior to that of the brass casting of Comparative Example 1, and that the corrosion resistance is comparable to that of the bronze casting of Comparative Example 2.

[0025]

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[0026]

The effects of the present invention are as follows. 1) The copper alloy according to the present invention hardly causes casting cracks in die casting including die casting, and has excellent castability.

2) The water supply / drainage fitting or valve made of the copper alloy according to the present invention is excellent in corrosion resistance against tap water, well water, industrial water, etc., particularly, dezincification corrosion resistance.

3) Since the copper alloy according to the present invention can be used for mold casting such as a water faucet which has been conventionally sand mold-cast, the conventional sand mold casting is not required, and the cost of dust countermeasures associated with the sand mold casting is eliminated. It will not take.

4) Since the copper alloy according to the present invention is excellent in mold castability, the surface quality of the cast product is good, so that the polishing amount is small and the polishing cost is lower than the conventional one.

5) According to the present invention, the area occupancy ratio of the β phase can be controlled by a simple heat treatment, and an alloy having excellent corrosion resistance can be manufactured.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a β phase ratio and a corrosion depth.

FIG. 2 is a diagram showing a relationship between a Sn addition amount and a solidification temperature range.

FIG. 3 is a diagram showing a relationship between zinc equivalent and corrosion depth.

FIG. 4 is a diagram showing a relationship between a zinc equivalent and a solidification temperature range.

─────────────────────────────────────────────────── ─── Continuation of front page (72) Masaaki Shima, 1-1-2 Nakajima, Kokurakita-ku, Kitakyushu City Totoki Equipment Co., Ltd. (72) Nobuo Shimamura 2-1-1 Nakajima, Kokurakita-ku, Kitakyushu No. Totoki Co., Ltd. (72) Inventor Kuki Nishiyama 2-1-1 Nakajima, Kokurakita-ku, Kitakyushu City Totoki Co., Ltd. (56) Reference JP-A-6-108184 (JP, A) JP 60-194035 (JP, A) JP 54-56925 (JP, A) JP 4-74838 (JP, A) JP 62-30862 (JP, A) JP 5-271850 (JP , A) JP-B 56-53624 (JP, B1) JP-B 58-38500 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) C22C 9/04 B22C 9/06 B22C 17/22 C22F 1/08

Claims (5)

(57) [Claims] 1. A copper alloy having two phases, an α phase and a β phase, having a composition of Sn, Sb, As, P, Pb, Al, F.
In the alloy for die casting, which is e, Zn, and Cu, the compounding ratio of each composition is Sn 0.05 to 0.2 wt%, Sb, As, or P, and any one kind or two or more kinds.
05 to 0.3% by weight, Zn = 1, Sn = 2, Pb = 1,
According to Guillet's coefficient of Al = 6, Fe = 0.9
Gold having a calculated zinc equivalent of 35.7 to 41.0% by weight, the balance of Cu, and a solidification temperature range of 17 ° C. or lower with an area occupation ratio of β phase of 15% or lower. Copper alloy for die casting. 2. Zn33.0-37.0 wt%, Pb
The copper alloy for die casting according to claim 1, which contains 0.5 to 3.0% by weight and 0.1 to 0.5% by weight of Al. 3. A copper alloy having two phases, an α phase and a β phase, having a composition of Sn, Sb, As, P, Pb, Al, F.
In the copper alloy for die casting, which is e, Zn, and Cu, the compounding ratio of each composition is Sn 0.05 to 0.2% by weight,
Any one or more of Sb, As or P 0.05
~ 0.3 wt%, Zn = 1, Sn = 2, Pb = 1, Al
= 6, Fe = 0.9 calculated by Guillet's coefficient
Zinc equivalent of 35.7 to 41.0 percent by weight, the balance being C
After casting, a copper alloy composed of u is cast at 450 to 550 ° C for 3
Hold for 0 minutes or more and within 3 hours, and set the β phase area occupation ratio to 1
A method for producing a copper alloy for die casting, which is excellent in corrosion resistance, characterized by being 5% or less. 4. The copper alloy comprises 33.0 to 37.0 wt% Zn, 0.5 to 3.0 wt% Pb, and 0.1 to 0.5 Al.
The method for producing a copper alloy for die casting having excellent corrosion resistance according to claim 3, wherein the copper alloy is contained in a weight percentage. 5. A water faucet comprising the copper alloy for die casting according to claim 1 or 2.