US20110081271A1

US20110081271A1 - Low-lead copper alloy

Info

Publication number: US20110081271A1
Application number: US12/575,102
Authority: US
Inventors: Wen Lin Lo; Xiao Ming Peng
Original assignee: Modern Islands Co Ltd
Current assignee: Modern Islands Co Ltd
Priority date: 2009-10-07
Filing date: 2009-10-07
Publication date: 2011-04-07

Abstract

The present invention provides a low-lead copper alloy, which includes 0.05 to 0.3 wt % of lead, 0.3 to 0.8 wt % of aluminum, 0.01 to 3 wt % of bismuth, 1 to 4 wt % of silicon, 0.1 to 1 wt % of tin, and more than 93.6% of copper and zinc, wherein copper is in an amount ranging from 61 to 78 wt %. The low-lead copper alloy of the present invention has excellent toughness and processability, and can provide increased resistance in an environment with a high concentration of chlorine ions.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to copper alloys, and more particularly, to a low-lead brass alloy.
2. Description of Related Art
Brass comprises copper and zinc, as major ingredients, usually at a ratio of about 7:3 or 6:4. In addition, brass usually comprises a small amount of impurities. In the context of improving the properties of brass, a conventional brass contains lead (mostly in the range of 1 to 3 wt %) to achieve the desired mechanical properties for use in industry, thereby becoming an important industrial material that is widely applicable in metallic devices and valves for use in pipelines, faucets and water supply and discharge system.
However, as the awareness of environmental protection grows and the impact of heavy metals on human health and issues like environmental pollution become major focuses, there is a tendency to restrict the usage of lead-containing alloys. Various countries, such as Japan and the United States, have sequentially amended relevant regulations in an effort to lower lead content in the environment by particularly demanding that no lead shall leach from lead-containing alloy materials used in products ranging from electronic appliances and automobiles to faucets and water systems, and stipulating that lead contamination shall be avoided during processing.
On another relevant matter, if the zinc content of brass exceeds 20 wt %, corrosion (such as dezincification) is likely to occur. This occurs particularly when brass is in an environment with a high concentration of chlorine ions (such as a marine environment) in which dezincification corrosion of brass is accelerated. Because dezincification seriously damages the structure of brass, the surface intensity of brass products is lowered and even pores may be formed in brass pipes. This significantly decreases the lifespan of brass products, thereby causing application problems.
Regarding the above issues of high lead content and dezincification, the industry continues to develop copper alloy formulations. For example, in addition to copper and zinc as main ingredients, TW421674, U.S. Pat. No. 7,354,489, US20070062615, US20060078458, US2004023441, US2002069942, etc., disclose lead-free copper alloy formulations containing silicon (Si) and other elements. However, the drawback of these alloys is poor machinability. CN10144045 discloses a lead-free copper alloy formulation comprising aluminum, silicon and phosphorus as major ingredients. Although this formulation can be used in casting, the alloy has poor machinability and a processing efficiency much lower than that of a lead brass. Thus, the alloy is not suitable for large-scale production. CN101285138 and CN101285137 disclose lead-free copper alloy formulations comprising phosphorus as a major element, but the formulations are likely to lead to defects like cracks and slag inclusions in the alloy when they are used in casting. For example, U.S. Pat. No. 7,297,215, U.S. Pat. No. 6,974,509, U.S. Pat. No. 6,955,378, U.S. Pat. No. 6,149,739, U.S. Pat. No. 5,942,056, U.S. Pat. No. 5,653,827, U.S. Pat. No. 5,487,867, U.S. Pat. No. 5,330,712, U.S. Pat. No. 5,637,160, US20060005901, US20040094243, US20070039667, etc. disclose brass alloys comprising added bismuth (Bi). The bismuth content of the above alloy formulations approximately range from 0.5 wt % to 7 wt %. However, the high bismuth content is likely to lead to defects like cracks and slag inclusions. Further, the high bismuth content leads to higher production costs, making it adverse to commercialization. U.S. Pat. No. 6,413,330 discloses a lead-free copper alloy formulation comprising ingredients like bismuth, silicon, etc. CN101440444 discloses a lead-free high zinc brass alloy. Because the zinc brass alloy has a combination of high silicon content and low copper content, the alloy has poor fluidity in the molten state. The poor fluidity makes the molten alloy fill in the cavity of a metallic mold more slowly, thereby causing defects like misrun. CN101403056 discloses a brass alloy comprising bismuth and manganese, but the high bismuth content is likely to cause defects like cracks and slag inclusions. The combination of low bismuth content and high manganese content causes a high degree of hardness, such that chip breaking is less likely to occur and machinability is poor. Moreover, the brass alloy formulation still has defects like poor casting properties and material embrittlement.
Furthermore, regarding the formulations of dezincification-resistant brass alloys, in addition to copper and zinc as principal ingredients, U.S. Pat. No. 4,417,929 discloses a formulation comprising iron, aluminum and silicon, U.S. Pat. No. 5,507,885 and U.S. Pat. No. 6,395,110 disclose formulations comprising phosphorus, tin and nickel, U.S. Pat. No. 5,653,827 discloses a formulation comprising iron, nickel and bismuth, U.S. Pat. No. 6,974,509 discloses a formulation comprising tin, bismuth, iron, nickel and phosphorus, U.S. Pat. No. 6,787,101 discloses a formulation comprising phosphorus, tin, nickel, iron, aluminum, silicon and arsenic, all at the same time, and U.S. Pat. No. 6,599,378 and U.S. Pat. No. 5,637,160 disclose adding selenium and phosphorus in brass alloys to achieve a dezincifying effect. Conventional dezincification-resistant brasses usually have higher lead contents (most in the range from 1 to 3 wt %), which facilitates cold/thermal processing of brass materials. However, they do not meet environmental requirements, because lead leaching is high and lead contamination is likely to occur during processing.
Thus, the industry continues to develop brass materials, and to seek for an alloy formulation that can substitute for lead-containing brasses while possessing desirable properties like good dezincification corrosion resistance, casting properties, machinability, corrosion resistance and mechanical properties.

SUMMARY OF THE INVENTION

In order to attain the above and other objectives, the present invention provides a dezincification-resistant copper alloy, comprising 0.05 to 0.3 wt % of lead, 0.3 to 0.8 wt % of aluminum, 0.01 to 0.3 wt % of bismuth, 1 to 4 wt % of silicon, 0.1 to 1 wt % of tin, and more than 93.6 wt % of copper and zinc, wherein copper is in an amount ranging from 61 to 78 wt %.
In an embodiment, the low-lead copper alloy of the present invention is comprised of copper and zinc in a total amount ranging from 93.6 to 98.54 wt %, and preferably more than 94 wt %. In an embodiment, copper is present in the low-lead copper alloy in an amount ranging from 61 to 78 wt %, preferably ranging from 62 to 74 wt %, and more preferably ranging from 66 to 72 wt %. As mentioned, the low-lead copper alloy of the present invention also comprises a silicon ingredient. Therefore, as compared with conventional lead brasses, the low-lead copper alloy of the present invention must have higher copper content, so as to provide the alloy material with good toughness.
In the low-lead copper alloy of the present invention, the lead content ranges from 0.05 to 0.3 wt %. In a preferred embodiment, the lead content ranges from 0.1 to 0.25 wt %, and more preferably ranges from 0.15 to 0.20 wt %. Addition of an appropriate amount of lead can increase the machinability of the brass alloy.
In the low-lead copper alloy of the present invention, the bismuth content is less than 0.3 wt %. In an embodiment, the bismuth content ranges from 0.01 to 0.3 wt %, preferably ranges from 0.05 to 0.25 wt %, and more preferably ranges from 0.1 to 0.2 wt %. Addition of an appropriate amount of bismuth is beneficial to increasing machinability of the alloy.
In the low-lead copper alloy of the present invention, the aluminum content ranges from 0.3 to 0.8 wt %. In a preferred embodiment, the aluminum content ranges from 0.4 to 0.7 wt %, and preferably ranges from 0.5 to 0.65 wt %. Addition of an appropriate amount of aluminum can increase the fluidity of a copper liquid, and improve the casting properties of the alloy material.
In the low-lead copper alloy of the present invention, the silicon content ranges from 1 to 4 wt %. In a preferred embodiment, the silicon content ranges from 1.5 to 3.5 wt %, and more preferably ranges from 2 to 3 wt %. Addition of an appropriate amount of silicon can increase the machinability of the brass, and increase the corrosion resistance and stress corrosion resistance of the alloy material in an environment with a high concentration of chlorine ions (such as a marine environment).
In the low-lead copper alloy of the present invention, the tin content ranges from 0.1 to 1 wt %. In a preferred embodiment, the tin content ranges from 0.2 to 0.9 wt %, and preferably ranges from 0.4 to 0.8 wt %. Addition of an appropriate amount of tin can increases the corrosion resistance of the alloy material in an environment with a high concentration of chlorine ions (such as a marine environment), and increases the intensity of the alloy material.
Moreover, addition of silicon and bismuth in the copper alloy maintains the machinability of the alloy material when it has low lead content, and increases the corrosion resistance of the alloy material in an environment with a high concentration of chlorine ions (such as a marine environment).
The low-lead copper alloy of the present invention can be a substitute material for conventional lead-containing brasses, and has excellent casting properties and good machinability and mechanical properties. Further, the low-lead copper alloy of the present invention comprises an extremely low lead content, thereby complying with environmental regulations. At the same time, the low-lead copper alloy of the present invention has good dezincification corrosion resistance, especially resistance to high concentrations of chlorine ions. Thus, the alloy of the present invention is suitable for application to environments with higher concentrations of chlorine ions, such as marine waters and swimming pools.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the relationship of the kinetic property and the zinc content of a copper alloy;

FIG. 2A is a metallographic structural distribution of a specimen of an C85710 lead brass;

FIG. 2B is a metallographic structural distribution of a specimen of a low-lead brass of the present invention;

FIG. 3A is a metallographic structural distribution of a specimen of the C85710 lead brass after a test of dezincification corrosion resistance was performed;

FIG. 3B is a metallographic structural distribution of a specimen of the low-lead brass of the present invention after a test of dezincification corrosion resistance was performed; and

FIG. 4 is a schematic diagram of an inlaid sample in an electrochemical test.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The detailed description of the present invention is illustrated by the following specific examples. Persons skilled in the art can conceive of other advantages and effects of the present invention based on the disclosure contained in the specification of the present invention.
Unless otherwise specified, the ingredients comprised in the copper alloy of the present invention, as discussed herein, are all based on the total weight of the alloy, and are expressed in weight percentages (wt %).
FIG. 1 is a graph showing the relationship of the kinetic property and the zinc content of a copper material. As for (α+β) dual phases, before the zinc content of the alloy reaches 45%, the intensity of the alloy increases with increasing zinc content at room temperature. Once the zinc content exceeds 45%, due to the appearance of γ phase in the metallographic distribution of the alloy, the embrittlement of the structure is increased, and the intensity of the alloy is drastically decreased. On the other hand, regarding a brass alloy formulation comprising complex ingredients, “zinc equivalents” of the elements comprised in the formulation are used to calculate the zinc content. Because the copper alloy of the present invention comprises silicon, the zinc equivalent of silicon is 10. That is, when 1% silicon is added in a Cu—Zn alloy, the metallographic structure of the alloy is comparable to the metallographic structure of a Cu—Zn alloy with 10% zinc content. As such, addition of silicon in the brass alloy enables α/(α+β) phase boundary in the Cu—Zn alloy to obviously shift to the copper side, strongly reducing in the α phase region. Therefore, the silicon content of the alloy should be no higher than 4 wt %. Silicon content of higher than 4 wt % is likely to lead to the presence of γ phase, which increases the embrittlement of the structure. Further, the copper alloy of the present invention should comprise higher copper content, so that good intensity and toughness of the alloy material are maintained. In the low-lead copper alloy of the present invention, the zinc equivalents of the comprised ingredients are as follows: zinc equivalent of 10 for silicon, zinc equivalent of 6 for aluminum, zinc equivalent of 2 for tin, zinc equivalent of 1 for lead, and zinc equivalent of 1 for bismuth.
The low-lead copper alloy formulation according to the present invention can have lead content that is lowered to the range of 0.05 to 0.3 wt %, to comply with international standards of lead content of pipeline materials in contact with water. Hence, the low-lead copper alloy according to the present invention is beneficial to the manufacture of faucets and lavatory components, pipelines for tap water, water supply systems, etc.
In an embodiment, the low-lead copper alloy of the present invention comprises 61 to 78 wt % of copper, 0.05 to 0.3 wt % of lead, 0.3 to 0.8 wt % of aluminum, 0.01 to 0.3 wt % of bismuth, 1 to 4 wt % of silicon, 0.1 to 1 wt % of tin, and zinc in balance.
In an embodiment, the low-lead copper alloy of the present invention comprises 62 to 74 wt % of copper, 0.1 to 0.25 wt % of lead, 0.4 to 0.7 wt % of aluminum, 0.05 to 0.25 wt % of bismuth, 1.5 to 3.5 wt % of silicon, 0.2 to 0.9 wt % of tin, and zinc in balance, wherein unavoidable impurities are less than 0.1 wt %.
In an embodiment, the low-lead copper alloy of the present invention comprises 66 to 72 wt % of copper, 0.15 to 0.25 wt % of lead, 0.5 to 0.65 wt % of aluminum, 0.2 to 0.3 wt % of bismuth, 2 to 3 wt % of silicon, 0.4 to 0.8 wt % of tin, and zinc in balance, wherein unavoidable impurities are less than 0.1 wt %.
The present invention is illustrated by the following exemplary examples.
The ingredients of the low-lead copper alloy of the present invention used in the following test examples are described below, wherein each of the ingredients is added at a proportion based on the total weight of the alloy.

Example 1


	Cu: 72.21 wt %	Al: 0.594 wt %
	Bi: 0.178 wt %	Si: 2.732 wt %
	Sn: 0.498 wt %	Pb: 0.141 wt %
	Zn: in balance

Example 2


	Cu: 74.23 wt %	Al: 0.451 wt %
	Bi: 0.169 wt %	Si: 2.941 wt %
	Sn: 0.645 wt %	Pb: 0.184 wt %
	Zn: in balance

Example 3


	Cu: 69.91 wt %	Al: 0.554 wt %
	Bi: 0.183 wt %	Si: 2.941 wt %
	Sn: 0.762 wt %	Pb: 0.136 wt %
	Zn: in balance

Example 4


	Cu: 62.47 wt %	Al: 0.684 wt %
	Bi: 0.187 wt %	Si: 2.123 wt %
	Sn: 0.417 wt %	Pb: 0.193 wt %
	Zn: in balance

Test Example 1

Rounded sand, a urea formaldehyde resin, a furan resin and a curing agent were used as raw materials to prepare a sand core using a core shooter, and the gas evolutions of the resins were measured using a testing machine for testing gas evolutions. The obtained sand core must be completely used within 5 hours, or it needs to be baked dry.
The low-lead brass alloy of the present invention and scrap returns were preheated for 15 minutes to reach a temperature higher than 400° C. Then, the alloy of the present invention and the scrap returns were mixed at a weight ratio of 7:1, along with addition of 0.2 wt % of refining slag, for melting in an induction furnace at a temperature ranging from 1100 to 1050° C. until the brass alloy reached a certain molten state (hereinafter referred to as “molten copper liquid”). A metallic gravity casting machine coupled with the sand core and the gravity casting molds to perform casting, and a temperature monitoring system further controlled temperatures so as to maintain the casting temperature in a range from 1060 to 1080° C. In each casting, the feed amount was preferably 1 to 2 kilograms, and the casting time was controlled to a range of 3 to 8 seconds. By the above high-temperature melting and low-temperature rapid casting, segregation of silicon in the alloy structure can be effectively avoided.
After the molds were cooled, the molds were opened and the casting head was cleaned. The mold temperatures were monitored so as to control the mold temperatures in a range from 200 to 220° C. to form casting parts. Then, the casting parts were released from the molds. Then, the molds were cleaned to ensure that the site of the core head was clean. A graphite liquid was spread on the surfaces of the molds following by cooling by immersion. The temperature of the graphite liquid for cooling the mold was preferably maintained in a range from 30 to 36° C., and the specific weight of the graphite liquid ranged from 1.05 to 1.06.
Inspection was performed on the cooled casting parts, and the casting parts were sent into a sand cleaning drum for cleaning. Then, an as-cast treatment was performed, wherein a thermal treatment for distressing annealing was performed on as-casts to eliminate the internal stress generated by casting. The as-casts were subsequently mechanically processed and polished, so that no sand, metal powder or other impurities adhered to the cavities of the casting parts. A quality inspection analysis was performed and the overall production yield was calculated by the following equation.
O.P. Yield=Number of Non-Defective Products/Total Number of Products×100%
The overall production yield reflects the qualitative stability of production processes. High qualitative stability of production processes ensures normal production.
Moreover, a conventional C85710 lead brass was used as a comparative example to produce products by the same process as described above. The ingredients, processing characteristics and overall production yield of each of the alloys are shown in Table 1.

TABLE 1

Ingredients, Processing Characteristics and Overall Production Yield of the Alloys

C85710 Lead Brass

Low-Lead Brass of the Present Invention

Category

Comparative	Comparative	Example	Example	Example	Example
Example 1	Example 2	1	2	3	4

Measured Cu	61.5	61.1	72.21	74.23	69.91	62.47
Content (%)
Measured Al	0.607	0.589	0.594	0.451	0.554	0.684
Content (%)
Measured Pb	1.47	1.54	0.141	0.184	0.136	0.193
Content (%)
Measured Bi	0.0119	0.0089	0.178	0.169	0.183	0.187
Content (%)
Measured Si	0.0002	0.0002	2.732	2.941	2.421	2.123
Content (%)
Measured Sn	<0.0005	<0.0005	0.498	0.645	0.762	0.417
Content (%)
Casting Yield	96%	95%	94%	93%	92%	91%
Processing	99%	99%	97%	97%	98%	97%
Yield
Polishing Yield	92%	94%	96%	95%	95%	96%
Overall	87.4%	88.4%	87.5%	85.7%	85.6%	84.7%
Production
Yield

The material fluidity of the low-lead brass of the present invention was close to that of the conventional C85710 lead brass. Further, the low-lead brass of the present invention had low sensitivity to embrittlement, and can maintain machinability of the material while not being particularly susceptible to defects like cracks. Thus, the low-lead brass of the present invention can satisfy the needs of production processes.
As shown in Table 1, as for the test group in which the low-lead brass of the present invention was used as a raw material, the yield can be more than 80%. Also, the material fluidity of the low-lead brass of the present invention was close to that of the conventional C85710 lead brass, and the yield of the low-lead brass of the present invention was also comparable to that of the C85710 lead brass. Hence, the low-lead brass of the present invention can indeed be a substitute material for the C85710 lead brass. The low-lead brass of the present invention also has the advantage of having low-lead content, thereby meeting environmental needs and statutes.

Test Example 2

FIGS. 2A and 2B show the metallographic structural distributions of the brass materials when the specimens were examined under an optical metallographic microscope at 100× magnification.
FIG. 2A shows the metallographic structural distribution of the C85710 lead brass (Comparative Example 2). The measured values of the major ingredients of the C85710 lead brass are as follows: Cu: 61.1 wt %, Al: 0.589 wt %, Pb: 1.54 wt %, Bi: 0.0089 wt %, and Si: 0.0002 wt %. The alloy had an α phase, and the grains were granular.
The measured values of the ingredients of the low-lead brass of Example 1 are as follows: Cu: 72.21 wt %, Al: 0.594 wt %, Pb: 0.141 wt %, Bi: 0.178 wt %, Si: 2.732 wt % and Sn: 0.498 wt %. FIG. 2B shows the metallographic structural distribution of the low-lead brass of Example 1. As shown in FIG. 2B, Example 1 exhibited an equitaxed dendritic crystal phase structure having low sensitivity to embrittlement. Because grains are dendritic and granular, chip breaking of the material can provide good machinability.

Test Example 3

A dezincification test was performed on the brass alloys of Example 1 and Comparative Example 1 to test the corrosion resistance of the brasses. The dezincification test was performed according to the Australian standard AS2345-2006 “Dezincification resistance of copper alloys.” Before a corrosion experiment was performed, a novolak resin was used for inlaying to make the exposed area of each of the specimens to be 100 mm². All the specimens were ground flat using a #600 metallographic abrasive paper, following by washing using distilled water. Then, the specimens were baked dry. The test solution was 1% CuCl₂solution prepared before use, and the test temperature was 75±2° C. The specimens and the CuCl₂solution were placed in a temperature-controlled water bath to react for 24±0.5 hours. The specimens were removed from the water bath, and cut along the vertical direction. The cross-sections of the specimens were polished, and then the depths of corrosion of the specimens were measured and observed under a digital metallographic electron microscope. Results are shown in FIGS. 3A and 3B.
As shown in FIG. 3A, the average depth of dezincification for Comparative Example 1 was 372.54 μm. As shown in FIG. 3B, the average depth of dezincification for Example 1 was 37.67 μm. It can be corroborated from the above that the low-lead brass of the present invention had better dezincification corrosion resistance.

Test Example 4

A test of the average levels of corrosion of the brass alloys of Example 1 and Comparative Example 1 was performed by an electrochemical method, so as to determine the average corrosion resistance of the brass alloys. The specimens of the brass alloys were polished and inlaid into a sample 1 as shown in FIG. 4, wherein the length of the surface of a brass specimen 11 exposed on the Inlaid Sample 1 was about 10 mm, the depth of the brass specimen 11 chelated in a resin layer 12 was about 12 mm, and the brass was coupled to a conductive wire 13.
The Inlaid Sample 1 was immersed in a 5% sodium chloride solution. A polarization curve of polarization potential versus electric current density was plotted by employing a linear polarization method, and the polarization resistance R_Pwas calculated using the following formula. Specifically, the greater the R_pvalue is, the better the average corrosion resistance of the material.
R _p =ΔE/ΔI,
where R_prepresents the polarization resistance, ΔE represents polarization potential, and ΔI represents external electric current density.

TABLE 2

Polarization Resistance Comparison

	Inlay Sample No.
	Category

Comparative Example 1

Example 1

	#1	#2	#3	Avg.	#	1	#2	#3	Avg.

Polarization	5.72	5.65	6.21	5.83	15.73	16.17	16.65	16.17
Resistance
R_p(KΩ/cm²)

As shown in Table 2, the R_pvalue (i.e., 16.17 KΩ/cm²) of the low-lead brass of the present invention was way higher than that (i.e., 5.83 KΩ/cm²) of the C85710 lead brass. It is corroborated that the low-lead brass alloy of the present invention had excellent average corrosion resistance, particularly in an environment with a high concentration of chlorine ions. Thus, the low-lead brass alloy of the present invention can be a material for products in an environment with a high concentration of chlorine ions. Examples include, but are not limited to, pipelines for use in swimming pools or pipelines for use in marine environments.

Test Example 5

A test of mechanical properties was performed on the brass alloys according to the standard set forth in IS06998-1998 “Tensile experiments on metallic materials at room temperature.” Results are shown in Table 3.

TABLE 3

Precipitation Amounts of the Metals in the Products

Mechanical Properties

Material

Tensile Strength (Mpa)

Elongation (%)

Type	1	2	3	4	5	Avg.	1	2	3	4	5	Avg.

Example 1	398	404	421	417	391	406.2	12	12	11	10	13	11.6
Comparative	356	337	363	374	367	359.6	12	11	13	13	12	12.2
Example 1

As shown in Table 3, the tensile strength of the low-lead brass alloy of the present invention was higher than that of the conventional C85710 lead brass, and the elongation of the low-lead brass alloy of the present invention was comparable to that of the C85710 lead brass, indicating that the low-lead brass alloy of the present invention had mechanical properties comparable to those of the C85710 lead brass. Nevertheless, the low-lead brass of the present invention has low-lead content, thereby meeting environmental demands. Thus, the low-lead brass of the present invention can indeed substitute for the C85710 lead brass in the manufacturing of products.

Test Example 6

A test was performed according to the standard set forth in NSF 61-2007a SPAC for the allowable precipitation amounts of metals in products, to examine the precipitation amounts of the metals of the brass alloys in an aqueous environment. Results are shown in Table 4.

TABLE 4

Precipitation Amounts of the Metals of the Products

			Comparative
	Upper Limit		Example 1 (after
	of Std.	Comparative	a lead-stripping	Example
Elements	Value (μg/L)	Example 1	treatment)	1

Lead	5.0	19.173	0.462	0.352
Bismuth	50.0	0.011	0.006	0.019
Aluminum	5.0	0.093	0.012	0.273
Tin	10.0	0.032	0.026	0.053

As shown in Table 4, the precipitation amounts of each of the metals of the low-lead brass of the present invention were all lower than the upper limits of the standard values. Thus, the low-lead brass alloy of the present invention complies with the requirements set forth in NSF 61-2007a SPAC. The lead content of the material of Comparative Example 1 that didn't experience a lead-stripping treatment substantially exceeded the standard value almost four-fold. However, the material of Example 1 easily met the standard value without experiencing a lead-stripping treatment. Further, the precipitation amount of lead of Example 1 was still lower than Comparative Example 1 after a lead-stripping treatment was performed. Thus, the low-lead brass alloy of the present invention is more environmentally friendly, and less threatening to human health.
In light of the above, the low-lead copper alloy of the present invention has mechanical processing properties comparable to those of the conventional C85710 lead brass. Further, the low-lead copper alloy of the present invention had better tensile strength and higher production yields in processing, and can substantially decrease the precipitation amount of lead in production. Thus, the alloy of the present invention is extremely suitable for replacing the alloy material of a conventional brass in manufacturing of products (such as lavatory products (e.g., faucets)). Moreover, the low-lead copper alloy of the present invention has excellent resistance to chlorine ions, thereby facilitating production of water supply systems for use in an environment with a high concentration of chlorine ions and facilitating production of copper products for use in a marine environment.
The invention has been described using exemplary preferred embodiments. However, it is to be understood that the scope of the invention is not limited to the disclosed arrangements. The scope of the claims, therefore, should be accorded the broadest interpretation, so as to encompass all such modifications and similar arrangements.

Claims

1. A low lead copper alloy, comprising:

0.05 to 0.3 wt % of lead;

0.3 to 0.8 wt % of aluminum;

0.01 to 0.3 wt % of bismuth;

1 to 4 wt % of silicon;

0.1 to 1 wt % of tin; and

more than 93.6% of copper and zinc, wherein the copper is in an amount ranging from 61 to 78 wt %.

2. The low lead copper alloy of claim 1, wherein the lead is in an amount ranging from 0.15 to 0.25 wt %.

3. The low lead copper alloy of claim 1, wherein the aluminum is in an amount ranging from 0.5 to 0.65 wt %.

4. The low lead copper alloy of claim 1, wherein the bismuth is in an amount ranging from 0.1 to 0.2 wt %.

5. The low lead copper alloy of claim 1, wherein the silicon is in an amount ranging from 2 to 3 wt %.

6. The low lead copper alloy of claim 1, wherein the copper is in an amount ranging from 66 to 72 wt %.

7. The low lead copper alloy of claim 1, wherein the copper is in an amount ranging from 62 to 74 wt %.