JPH08337831A - Copper alloy for die casting excellent in corrosion resistance, production of the same alloy and faucet using the same alloy - Google Patents

Abstract

PURPOSE: To produce a copper alloy for die casting excellent in die castability and corrosion resistance, to provide a producing method for improving the corrosion resistance of the same alloy and to produce a faucet excellent in corrosion resistance. CONSTITUTION: This copper alloy is the one in which, a in a copper alloy composed of two phases of an α phase and a β phase, at least, by weight, 0.05 to 0.2% Sn and one or >= two kinds among Sb, As and P by 0.05 to 0.3% are contained, the maximum corrosion depth is regulated to <=200μm (JBMA test) and the solidifying temp. range is regulated to <=17 deg.C or is the one in which, in a copper alloy composed of two phases of an α phase and a βphase, at least, 0.05 to 0.2% Sn and or >= two kinds among Sb, As and P by 0.05 to 0.3% are contained, and zinc equivalent is regulated to 35.7 to 41.0%. In either alloy, the area occupancy ratio of the βphase is preferably regulated to <=15%. Moreover, the same copper alloy is suitable for faucet fittings, particularly for the pressure resistant parts.

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]

In the copper alloy for die casting according to the present invention, at least 0.05 to 0.2% by weight of Sn, Sb, As or a copper alloy consisting of two phases of α phase and β phase is used. P
Any one or two or more of 0.05 to 0.3% by weight, a maximum corrosion depth of 200 μm or less (JBMA test), a solidification temperature range of 17 ° C or less, a copper alloy, or an α phase and a β alloy. At least S in a copper alloy consisting of two phases
n 0.05-0.2 wt%, Sb, As or any one kind of P or two or more 0.05-0.3 wt% is contained,
It is a copper alloy for die casting having a zinc equivalent of 35.7 to 41.0% by weight. Zn33.
0 to 37.0 wt% and Al 0.1 to 0.5 wt% can be contained.

Further, according to the present invention, it is possible to produce a copper alloy for die casting which is excellent in corrosion resistance by heat-treating each of the die casting alloys after casting to reduce the β phase area occupancy ratio. In particular, the area occupancy ratio of the β phase is reduced to 15% or less to improve the corrosion resistance.

Each of the above-mentioned copper alloys for die casting is used in the range of 450 to 550.
By heat treatment at ° C for 30 minutes or more and within 3 hours to reduce the β phase area occupancy rate to 15% or less, a copper alloy for die casting with excellent corrosion resistance can be manufactured. When it is 8% or less, it is possible to manufacture a copper alloy for die casting, which is excellent in corrosion resistance for a water faucet metal fitting, and is particularly suitable for a pressure resistant portion of the water faucet metal fitting.

[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 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) Impurities Inevitable impurities such as 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 casting, dust and the like are harmful to the human body, and therefore there is a problem in that dust countermeasures are expensive. 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 the front page (72) Inventor Jun Yamauchi 2-1-1 Nakajima, Kokurakita-ku, Kitakyushu City Tohoku Kikai Co., Ltd. (72) Inventor Masaaki Shima 2-1-1 Nakajima, Kokurakita-ku, Kitakyushu No. Totoki Co., Ltd. (72) Inventor Nobuo Shimamura 2-1-1 Nakajima, Kokurakita-ku, Kitakyushu City In-Tokoki Co., Ltd. (72) Kuki Nishiyama 2-1-1 Nakajima, Kokurakita-ku, Kitakyushu No. Totoki Equipment Co., Ltd.

Claims (11)

[Claims] 1. A copper alloy consisting of two phases, an α phase and a β phase, containing at least one of 0.05 to 0.2% by weight of Sn and Sb, As or P or two or more of 0.05 to 0. A copper alloy for die casting, containing 0.3% by weight, a maximum corrosion depth of 200 μm or less (JBMA test), and a solidification temperature range of 17 ° C. or less. 2. A copper alloy consisting of two phases, an α phase and a β phase, containing at least one of 0.05 to 0.2% by weight of Sn, Sb, As, and P or two or more of 0.05 to 0. A copper alloy for die casting, containing 0.3% by weight and having a zinc equivalent of 35.7 to 41.0% by weight. 3. The copper alloy for die casting according to claim 1, wherein the area occupancy ratio of the β phase is 15% or less. 4. Zn 33.0-37.0 wt%, Al
The copper alloy for die casting according to claim 1, 2 or 3, wherein the copper alloy contains 0.1 to 0.5% by weight. 5. The copper alloy for casting metal molds for faucet fittings according to claim 1, wherein the area occupancy ratio of the β phase is 8% or less. 6. A copper alloy consisting of two phases, an α phase and a β phase, containing at least one of 0.05 to 0.2% by weight of Sn and Sb, As or P or two or more of 0.05 to 0. A die having excellent corrosion resistance, characterized by containing a copper alloy containing 0.3% by weight of zinc and having a zinc equivalent of 35.7 to 41.0% by weight and then heat-treating it after casting to reduce an area occupancy ratio of β phase. Manufacturing method of copper alloy for casting. 7. The copper alloy for die casting having excellent corrosion resistance according to claim 6, wherein the copper alloy contains 33.0 to 37.0% by weight of Zn and 0.1 to 0.5% by weight of Al. Manufacturing method. 8. A heat treatment for 30 minutes or more and 3 hours or less at 450 to 550 ° C. after casting to make the β phase area occupation ratio 15%.
The method for producing a copper alloy for die casting having excellent corrosion resistance according to claim 6 or 7, characterized by the following. 9. The method for producing a copper alloy for die casting for a faucet fitting according to claim 6, 7 or 8, wherein the area occupancy ratio of the β phase is 8% or less. 10. A copper alloy consisting of two phases, an α phase and a β phase, containing at least 0.05 to 0.2 wt% Sn, Sb and As.
Or P, containing one or more of 0.05 to 0.3% by weight, zinc equivalent of 35.7 to 41.0% by weight, and β phase area occupancy ratio of 15% or less. A faucet characterized by using a copper alloy that is. 11. A copper alloy consisting of two phases, an α phase and a β phase, containing at least 0.05 to 0.2 wt% Sn, Sb and As.
Or, one or more of P is contained in an amount of 0.05 to 0.3% by weight, zinc equivalent is 35.7 to 41.0% by weight, and the β phase area occupancy ratio is 8% or less. A copper alloy
A water faucet characterized by being used at least in a pressure resistant portion.