KR19990034664A - Casting brass alloy and its manufacturing method - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a brass alloy used for casting and a manufacturing method thereof.

2. Technical problem to be solved by the invention

The present invention, while using a low-cost brass scrap containing lead (Pb) as the main raw material, while suppressing the elution amount of lead (Pb) to the maximum, while improving the machinability, castability, corrosion resistance and the like (Cu) -zinc ( Zn) brass alloy for castings.

3. Summary of Solution to Invention

The present invention uses the brass scrap, copper (Cu) scrap and zinc (Zn) now, while the content of lead (Pb), which is impurity, is 0.2% by weight or less, copper (Cu) is 56.0 to 61.0% by weight, Zinc (Zn) is the residual amount of the alloy, 0.1 to 0.5% by weight of aluminum (Al) to improve mechanical strength and castability, 0.1 to 0.5% by weight of iron (Fe) to improve mechanical strength, castability and 0.2 ~ 0.6 wt% of tin (Sn) to improve corrosion resistance, 0.15 ~ 0.5 wt% of nickel (Ni) as an anticorrosion aid, and 0.1 ~ 0.5 wt% of bismuth (Bi) to improve processability Then, charge it into the melting furnace and dissolve at 950 ~ 1050 ℃ for 1 ~ 2 hours, adjust the planned components, and raise the temperature of the melting furnace to 1060 ~ 1090 ℃ to keep the nonmetallic substance floating while removing for 5 ~ 15 minutes, Lower the furnace temperature to 1000 ~ 1050 ℃ and charge 3 ~ 20ppm boron (B) as grain refiner. It can be achieved by the composition of the brass alloy for casting "and the method of manufacturing the same, which is tapping after flow for 5 to 15 minutes.

4. Important uses of the invention

The brass alloy for casting manufactured by the present invention is excellent in workability while suppressing the dissolution of lead (Pb), and it can be used for construction and water supply and drainage parts, drinking water and cold and hot water parts, tableware-related items, food cookers and various parts. Can be.

Description

Casting brass alloy and its manufacturing method

The present invention relates to a brass alloy, and more particularly, to a brass alloy for castings based on copper (Cu) and zinc (Zn) and a manufacturing method thereof.

Brass alloys for casting have a wide variety of uses, from mechanical, electrical, electronic, automotive, and building materials to everyday life, and must have suitable properties for these various applications. In order to obtain a variety of alloying elements are added.

Of these, one of the most required physical properties is workability, 1.0 to 4.5% by weight of lead (Pb) is added in order to improve the workability, lead (Pb) has a grain-like structure with little solid solution in brass As it is distributed in the chip, the chip is crushed during processing, and as the lubricant, Pb, which has a relatively low melting point due to heat generated during processing, acts as a lubricant, reducing the processing resistance. In addition, it has been treated as an essential part of the manufacture of free cutting brass because it also has the effect of extending the life of cutting tools.

However, lead (Pb) is absorbed into the human body through food and drinking water as well as breathing and contact with the air, accumulates in the bones, and develops in children in the growing phase, and osteoporosis in adults. It causes the skin and eyes, such as jaundice, vomiting, digestive disorders, lethargy, gum black line, hypertension, and visual impairment, as well as affects the brain, causing cramps and shock. The use of this eluted brass alloy is strictly regulated.

In order to solve the above problems, many studies have been conducted on brass alloys in which bismuth (Bi) is added instead of lead (Pb). As a result, US Patent No. 5,288,458, Japanese Patent Application Laid-Open No. Related technologies such as Japanese Patent Application Laid-Open No. 5-255778, Japanese Laid-Open Patent Publication No. 54-135618, International Publication No. 93-24670, and International Publication No. 94-24325 have been disclosed.

In the case of U.S. Patent No. 5,288,458, 1.8 to 5.0% by weight of musbis (Bi) is added to a copper (Cu) -zinc (Zn) binary brass alloy having a mixed phase of alpha + beta (α + β) two phases. The remainder is to disclose an alloy having improved cold workability by using aluminum (Al), tin (Sn), silicon (Si), magnesium (Mg), lead (Pb), etc. as an impurity. Processability has been greatly improved, but as the relatively expensive bismuth (Bi) is added a lot of disadvantages in terms of economics, there is a problem that the mechanical properties are weak due to the excessive addition of bismuth (Bi).

In the case of Japanese Patent Laid-Open No. 5-255778, 0.5 to 4.0 weight of brass alloy composed of 57 to 61% by weight of copper (Cu), 0 to 0.9% by weight of mitshu metal, and zinc (Zn) Bismuth (Bi) is added to the brass alloy composed of 57 to 61% by weight of copper (Cu), 0.1 to 0.5% by weight of mitschmethyl and zinc (Zn). The addition of 0.5 to 3.0% by weight of lead (Pb) is disclosed for the brass alloy with excellent workability. In the case of this alloy, the content of bismuth (Bi) is added to have an economically beneficial effect, There is a problem that can not prevent the dissolution of lead (Pb) fundamentally.

In the case of Japanese Laid-Open Patent Publication No. 54-135618, the copper (Cu) content is 58 to 65% by weight, and the lead (Pb) content is 0.1% or less by weight of copper (Cu) -zinc (Zn) as an unavoidable impurity. Bismuth (Bi) was added to 0.5% to 1.5% by weight of the brass alloy to reveal excellent workability and forging, but in this case, the content of lead (Pb) managed as impurities is 0.1% or less. According to the regulations, if this alloy is to be manufactured using existing brass scrap, there is a problem in that it is difficult to lower the content of lead (Pb), thereby increasing the manufacturing cost.

International Publication No. 93-24670 discloses 57-62% by weight of copper (Cu), 3.0% by weight of other alloying components and melt management impurities, additives for improving machinability, brass containing zinc (Zn) as a residue. A technique of adding bismuth (Bi) to an alloy is disclosed, and other alloying components, additives and impurities for improving machinability are aluminum (Al), boron (B), lead (Pb), tin (Sn), and iron. (Fe), antimony (Sb), silicon (Si), manganese (Mn), nickel (Ni), and the like are listed.

In the case of this alloy, most of the above-mentioned shortcomings have excellent workability and main components. However, pure copper (Cu) and zinc (Zn) should be used for managing lead (Pb), which is an impurity. Due to this problem, the manufacturing cost is increased.

In view of the above problems, the present invention is fundamentally excellent in machinability, castability and corrosion resistance, even though the elution of lead (Pb) is released at 1 ppm or less specified by the Ministry of Health and Welfare. It is to provide a brass alloy for casting and a method of manufacturing the same that can be produced at a cost.

1 is a graph showing the change in leaching amount of lead (Pb) according to the leaching solution and lead (Pb) content

Figure 2a is a graph of the change in cutting force according to the lead (Pb) content

Figure 2b is a graph of the change in cutting force according to the bismuth (Bi) content

Figure 3a is an optical micrograph of the cutting chip shape when the lead (Pb) content is 2.87% by weight

Figure 3b is an optical micrograph of the cutting chip shape when the lead (Pb) content is 1.37% by weight

Figure 3c is an optical micrograph of the cutting chip shape when the lead (Pb) content is 0.62% by weight

Figure 3d is an optical micrograph of the cutting chip shape when the lead (Pb) content is 0.09% by weight

Figure 3e is a micrograph of the cutting chip shape when the bismuth (Bi) content is 0.74% by weight

Figure 3f is a micrograph of the cutting chip shape when the bismuth (Bi) content is 0.45% by weight

Figure 3g is an optical micrograph of the cutting chip shape when the bismuth (Bi) content is 0.33% by weight

Figure 3h is an optical micrograph of the cutting chip shape when the bismuth (Bi) content is 0.14% by weight

Figure 4a is an optical micrograph of the microstructure without the addition of boron (B)

Figure 4b is an optical micrograph of the microstructure when the boron (B) is added 3.3ppm

Figure 4c is an optical micrograph of the microstructure when boron (B) is added 9.4ppm

Figure 4d is an optical micrograph of the microstructure when the boron (B) is added 14.3ppm

5A is an optical micrograph of corrosion characteristics when 0.15 wt% tin (Sn) and 0.03 wt% nickel (Ni) are added.

5B is an optical microscope photograph of corrosion characteristics when 0.53 wt% tin (Sn) and 0.03 wt% nickel (Ni) are added.

5C is an optical microscope photograph of corrosion characteristics when 0.43 wt% tin (Sn) and 0.25 wt% nickel (Ni) are added.

5D is an optical microscope photograph of corrosion characteristics when 0.41 wt% tin (Sn) and 0.21 wt% nickel (Ni) are added.

Brass alloy for casting of the present invention for solving the above problems is 56.0 ~ 61.0% by weight of copper (Cu), 0.1 ~ 0.5% by weight of aluminum (Al), 0.1 ~ 0.5% by weight of iron (Fe), 0.2 ~ 0.6% by weight of tin (Sn), 0.15 to 0.5% by weight of nickel (Ni), 0.2% by weight of one lead (Pb), zinc for additives and grain refining agents to enhance processability, which can be added as needed (Zn).

Lead (Pb) in the composition element is good if it does not basically contain, but lead (Pb) is an impurity introduced with other metals in the manufacturing process of the brass alloy, except when using conventional brass scrap, etc. Not only is it difficult to do the following, but the processing cost is excessive, and in order to release below the prescribed value prescribed by the Ministry of Health and Welfare, it is preferable to control it to 0.2 weight% or less by prior analysis.

Aluminum (Al) is a metal added to improve the castability as well as the mechanical strength of the alloy. When it is contained in an amount of 0.1% by weight or less, the fluidity becomes poor in a molten state, and when it is contained in an amount of 0.5% by weight or more, Although the composition can be improved, aluminum oxide (Al ₂ O ₃ ) is formed in the barrel, which adversely affects the formation of the alloy.

Tin (Sn) is an element added to improve not only castability but also corrosion resistance by suppressing elution of lead (Pb), and it is difficult to obtain an effect of improving castability at 0.2 wt% or less, and is added at 0.6 wt% or more. In the case of forming a weak gamma (Y) phase, there is a problem that the mechanical properties deteriorate, so 0.2 to 0.6% by weight should be added. Nickel (Ni) is added as an assistant for improving the corrosion resistance of tin (Sn), and is added in an amount of 0.15 to 0.5 wt% less than that of tin (Sn).

Iron (Fe) is added to improve the mechanical strength, the higher the content, the mechanical strength can be improved, so should be added in more than 0.1% by weight, if more than 0.5% by weight of other metal and intermetallic compound There is a problem that the alloy becomes weak by forming a.

In addition to the above components, bismuth (Bi) may be added in order to prevent a decrease in the mechanical processability caused by insufficient content of lead (Pb) according to the nature of the product to be manufactured, but bismuth (Bi) is relatively As it is an expensive metal and occupies an important position for the cost increase of the product, it is recommended to add 0.1 to 0.5% by weight in accordance with the composition of the composition, and to add fine grains of the alloy to obtain a beautiful surface during polishing. It is preferable to add boron (B) to become within the range of 3-10 ppm.

The manufacture of the brass alloy for castings having the composition described above uses brass scrap, copper (Cu) scrap and zinc (Zn) now to quantitate by compounding according to the lead (Pb) content in the scrap. , Fe (Fe) is a ferro-copper alloy of 10% by weight iron (Fe) -copper (Cu) master alloy in the form of the amount corresponding to the calculation, and other alloying elements that are lacking in the formulation calculation of scrap Phosphorous tin (Sn), aluminum (Al), nickel (Ni), bismuth (Bi), etc., are added to the present state and added to the melting furnace, and are first melted for 1 to 2 hours at 950 to 1050 ° C. When the ingredients are matched and finally the requirements of the chemical components are met, the secondary furnace is raised to 1060 to 1090 ° C for 5 to 15 minutes while the nonmetallic substance is floated and removed, and the furnace temperature is lowered to 1000 to 1050 ° C. Let's do it.

Since non-metallic inclusions cause a pit on the surface of the product, it is necessary to raise the melting furnace temperature to 1060 to 1090 ° C. for 5 to 15 minutes while lifting the non-metallic inclusions to remove slag.

In addition, the addition of boron (B) as the grain refining agent, at the melting temperature of 1000 ~ 1050 ℃ just before tapping, to form a powdered state in the form of agglomerate and forced to the bottom of the melting furnace, until the alloy component is completely melted 5 Hold for 15 minutes.

The reason for forcing the boron (B) into the bottom of the furnace in the above method is to prevent the loss of boron due to the generation of boron oxide by reacting with oxygen in the air, and to diffuse and dissolve uniformly from the bottom of the furnace. It is to ensure that.

Hereinafter, the present invention will be described in detail through Examples and Comparative Examples.

Examples 1 and 2 and Comparative Examples 1 to 5 are for the dissolution test of lead (Pb), the implementation status and results are as follows.

Example 1

57.5-58.0 wt% of copper (Cu), 0.1-0.15 wt% of lead (Pb), 0.1-0.15 wt% of iron (Fe), 0.15-0.2 wt% of tin (Sn), 0.3-0.4 wt% of aluminum (Al), Nickel (Ni) 0.1 wt% or less, the remainder is zinc (Zn) brass alloy, brass (Cu) scrap, zinc (Zn) now and iron (Fe) -copper (Cu) master alloy Then, tin (Sn), aluminum (Al), nickel (Ni) is added to the melting furnace, and the mixture is calculated. The mixture is heated for 1 hour and 30 minutes while stirring at 1000 ° C to completely dissolve the chemical composition, and then the temperature of the melting furnace is adjusted. After raising to 1070 ℃ and maintained for 10 minutes to remove the non-metallic inclusions in the slag state, after lowering the temperature of the melting furnace to 1000 ℃ by tapping with a prepared ingot mold and analyzed the components and the results are shown in Table 1.

Example 2

Copper (Cu) 60.5--61.0 wt%, Lead (Pb) 0.05-0.1 wt%, Iron (Fe) 0.15-0.2 wt%, Tin (Sn) 0.15-0.2 wt%, Aluminum (Al) 0.1-0.2 wt% , Brass (Cu) scrap, zinc (Zn) now and iron (Fe) -copper (Cu) master alloy to produce brass alloys of 0.1 wt% or less of nickel (Zn), the remainder being zinc (Zn) Then, tin (Sn), aluminum (Al) and nickel (Ni) are added to the melting furnace and blended with each other. The mixture is heated for 1 hour and 30 minutes while stirring at 1000 ° C to completely dissolve the chemical composition, and then the temperature of the melting furnace. After raising to 1090 ℃ and maintained for 10 minutes to remove the non-metallic inclusions in the slag state, lowering the temperature of the melting furnace to 1020 ℃ after tapping with a prepared ingot mold and analyzed the components are shown in Table 1 .

Comparative Example 1

61.0-61.5 wt% of copper (Cu), 2.5-3.0 wt% of lead (Pb), 0.55-0.65 wt% of iron (Fe), 0.6-0.7 wt% of tin (Sn), 0.1-0.2 wt% of aluminum (Al), Pure copper, zinc (Zn) now and iron (Fe) -copper (Cu) master alloys, tin (Sn), to produce brass alloys of 0.15 to 0.25% by weight of nickel (Zn), the remainder being zinc (Zn) Aluminum (Al) and nickel (Ni) are mixed and charged into a melting furnace, heated for 1 hour and 30 minutes while stirring at 1000 ° C to completely dissolve the chemical composition, and then the temperature of the melting furnace is raised to 1070 ° C for 10 minutes. After maintenance, the non-metallic inclusions in the slag state were removed, the temperature of the melting furnace was lowered to 1000 ° C., followed by tapping with a prepared ingot mold to analyze the components. The results are shown in Table 1.

Comparative Example 2

61.5-62.0 wt% of copper, 1.5-2.0 wt% of lead (Pb), 0.2-0.3 wt% of iron (Fe), 0.25-0.35 wt% of tin (Sn), 0.5-0.6 wt% of aluminum (Al), Pure copper, zinc (Zn) now and iron (Fe) -copper (Cu) master alloys, tin (Sn), to produce brass alloys of 0.1 to 0.15% by weight of nickel (Zn), the remainder being zinc (Zn) Aluminum (Al) and nickel (Ni) are mixed and charged into a melting furnace, heated for 1 hour and 30 minutes while stirring at 1000 ° C to completely dissolve the chemical components, and then the temperature of the melting furnace is raised to 1090 ° C for 10 minutes. After the maintenance, the non-metallic inclusions in the slag state were removed, and the temperature of the melting furnace was lowered to 1020 ° C., followed by tapping with a prepared ingot mold to analyze the components. The results are shown in Table 1.

Comparative Example 3

Copper (Cu) 58.5-59.0 wt%, Lead (Pb) 1.0-1.5 wt%, Iron (Fe) 0.1 wt% or less, Tin (Sn) 0.15-0.2 wt%, Aluminum (Al) 0.6-0.7 wt%, Nickel (Ni) 0.1 wt% or less, to produce a brass alloy with the remainder zinc (Zn), pure copper, zinc (Zn) now and iron (Fe) -copper (Cu) master alloy, tin (Sn), aluminum ( Al) and nickel (Ni) were mixed and charged into a melting furnace, heated at 1000 ° C for 1 hour and 30 minutes to completely dissolve, and the chemical components were adjusted. Then, the temperature of the melting furnace was raised to 1090 ° C for 10 minutes. Next, the non-metallic inclusions injured in the slag state were removed, and the temperature of the melting furnace was lowered to 1020 ° C., followed by tapping with a prepared ingot mold to analyze the components. The results are shown in Table 1 below.

Comparative Example 4

Copper (Cu) 58.0-58.5 wt%, Lead (Pb) 0.5-1.0 wt%, Iron (Fe) 0.2-0.3 wt% or less Tin (Sn) 0.15-0.2.wt%, Aluminum (Al) 0.25-0.35 wt% In order to produce brass alloys of 0.1 wt% or less of nickel (Ni) and the remainder of zinc (Zn), pure copper, zinc (Zn) now and iron (Fe) -copper (Cu) mother alloys, tin (Sn), Aluminum (Al) and nickel (Ni) are mixed and charged into a melting furnace, heated for 1 hour and 30 minutes while stirring at 1000 ° C to completely dissolve the chemical components, and then the temperature of the melting furnace is raised to 1090 ° C for 10 minutes. After the maintenance, the non-metallic inclusions in the slag state were removed, and the temperature of the melting furnace was lowered to 1020 ° C., followed by tapping with a prepared ingot mold to analyze the components. The results are shown in Table 1.

Comparative Example 5

56.5-57.5% by weight of copper (Cu), 0.2-0.3% by weight of lead (Pb), 0.1-0.2% by weight of iron (Fe), 0.2-0.25% by weight of tin (Sn), 0.25-0.35% by weight of aluminum (Al) Pure copper, zinc (Zn) now and iron (Fe) -copper (Cu) master alloys, tin (Sn), aluminum to produce brass alloys with 0.1% by weight of nickel (Ni) and the remainder zinc (Zn) (Al) and nickel (Ni) are mixed and charged into a melting furnace, heated for 1 hour and 30 minutes while stirring at 1000 ° C to completely dissolve the chemical components, and then the temperature of the melting furnace is raised to 1090 ° C for 10 minutes. After removing the non-metallic inclusions in the slag state, lowering the temperature of the melting furnace to 1020 ℃ and tapping with a prepared ingot mold for component analysis and the results are shown in Table 1.

TABLE 1

(Unit: weight%)

<Pb dissolution test>

According to the standards and specifications of the Ministry of Health and Welfare Notice No. 95-47 No. 6 apparatus and containers and packaging, the alloy prepared in the above Examples and Comparative Examples was sampled from the ingot and the surface area was calculated. Distilled water and 4% acetic acid solution were used as the leaching solution, respectively, at a rate of 2 ml. After dipping the sample in the leaching solution, the sample was covered with a glass plate, and sometimes stirred for 30 minutes while maintaining 95 ° C. Lead (Pb) contained in the leaching solution The content of was measured and the results are shown in Table 2.

TABLE 2

As can be seen from Table 2 and Figure 1 in the case of Examples 1 and 2, the content of lead (Pb) is 0.13% by weight, 0.09% by weight, respectively, as well as distilled water, 4% acetic acid solution in the Ministry of Health and Welfare Lead (Pb) is eluted below the standard value of 1 ppm, but in the case of Comparative Example 5 in which the content of lead (Pb) is 0.25% by weight, the elution amount of lead (Pb) enters the pass line when distilled water is used. In the case of 4% acetic acid solution, it is shown as 1.20 ppm exceeding the reference value, and lead (Pb) is eluted far in excess of the reference value even in Comparative Examples 1 to 4, which is the case of an alloy having a high content of lead (Pb). Able to know.

Examples 3 to 5 and Comparative Example 6 are examples for revealing an appropriate amount of bismuth (Bi) added in order to prevent a decrease in machinability caused by insufficient content of lead (Pb).

Example 3

57.5-58.0 wt% of copper (Cu), 0.1-0.2 wt% of lead (Pb), 0.15-0.25 wt% or less of iron (Fe), 0.2-0.3 wt% of tin (Sn), 0.2-0.3 wt% of aluminum (Al) , Nickel (Ni) 0.1% by weight or less, bismuth (Bi) 0.4-0.5% by weight, the rest of the brass to produce a brass alloy, brass (Cu) scrap, zinc (Zn) now and The iron (Fe) -copper (Cu) master alloy, tin (Sn), aluminum (Al), and nickel (Ni) bismuth (Bi) are added to the melting furnace and charged into the melting furnace, and the mixture is stirred at 1000 ° C for 30 hours. Heat for a minute to completely dissolve to adjust the chemical composition, then raise the temperature of the furnace to 1090 ℃, hold for 10 minutes, remove the floating non-metallic inclusions in the slag state, lower the temperature of the furnace to 1020 ℃ and prepared ingot state The component was analyzed by tapping with a mold and the results are shown in Table 3.

Example 4

Copper (Cu) 56.0-56.5 wt%, Lead (Pb) 0.05-0.1 wt%, Iron (Fe) 0.15-0.25 wt%, Tin (Sn) 0.4-0.5 wt%, Aluminum (Al) 0.2-0.3 wt%, Nickel (Ni) 0.1% by weight or less, Bismuth (Bi) 0.3-0.4% by weight, the remainder of the brass alloy, copper (Cu) scrap, zinc (Zn) now and iron to produce a brass alloy The (Fe) -copper (Cu) master alloy, tin (Sn), aluminum (Al) and nickel (Ni) bismuth (Bi) is added to the melting furnace and charged into the melting furnace, followed by stirring for 1 hour and 30 minutes. Heated to complete dissolution to adjust the chemical composition, then the temperature of the melting furnace to 1090 ℃ to maintain for 10 minutes, then removing the non-metallic inclusions in the slag state, lowering the temperature of the melting furnace to 1020 ℃ and prepared ingot state mold The component was analyzed by tapping with and the results are shown in Table 3.

Example 5

57.5-58.0 wt% of copper (Cu), 0.1-0.2 wt% of lead (Pb), 0.3-0.4 wt% of iron (Fe), 0.2-0.3 wt% of tin (Sn), 0.2-0.3 wt% of aluminum (Al), Nickel (Ni) 0.1% by weight or less, Bismuth (Bi) 0.1-0.2% by weight, the remainder of the brass alloy, copper (Cu) scrap, zinc (Zn) now and iron to produce a brass alloy The (Fe) -copper (Cu) master alloy, tin (Sn), aluminum (Al) and nickel (Ni) bismuth (Bi) is added to the melting furnace and charged into the melting furnace, followed by stirring for 1 hour and 30 minutes. Heated to complete dissolution to adjust the chemical composition, then the temperature of the melting furnace to 1090 ℃ to maintain for 10 minutes, then removing the non-metallic inclusions in the slag state, lowering the temperature of the melting furnace to 1020 ℃ and prepared ingot state mold The component was analyzed by tapping with and the results are shown in Table 3.

Comparative Example 6

58.0-58.5 wt% of copper (Cu), 0.05-0.1 wt% of lead (Pb), 0.15-0.2 wt% of iron (Fe), 0.1-0.2 wt% of tin (Sn), 0.1-0.2 wt% of aluminum (Al), Pure copper, zinc (Zn) now and iron (Fe) -copper (Cu) for the production of brass alloys of 0.1% by weight or less of nickel (Ni), 0.7 to 0.8% by weight of bismuth (Bi), and the balance of zinc (Zn) ) The master alloy, tin (Sn), aluminum (Al), and nickel (Ni) bismuth (Bi) are added to the melting furnace and mixed with each other.The mixture is heated for 1 hour and 30 minutes with stirring at 1000 ° C to completely dissolve the chemicals. After adjusting the components, the temperature of the melting furnace was raised to 1090 ° C. for 10 minutes to remove the non-metallic inclusions in the slag state, and the temperature of the melting furnace was lowered to 1020 ° C., followed by tapping with a prepared ingot mold to analyze the ingredients. The results are shown in Table 3.

TABLE 3

(Unit: weight%)

<Processing characteristics evaluation experiment>

The change in processing characteristics of Examples 2 to 5 and Comparative Examples 1 and 3 to 6 was measured and the results are shown in Table 4.

In the case of excellent workability, the cutting force is low, and the chip is broken in a shear-like shape. In the case of poor workability, the cutting force is high and the chip curls. For this, the cutting force and chip shape were observed.

The cutting force was used as a drill method. The drill was a high speed steel drill with a diameter of 3.5 mm and the cutting speed was performed at 1100 rpm and a cutting depth of 10 mm.

TABLE 4

As can be seen from the experimental results for the cutting resistance of Example 2, Comparative Example 1 and Comparative Examples 3 to 5 of Table 4 and the graph of FIG. 2A, the numerical value of the cutting resistance decreases as the content of lead (Pb) decreases. It can be seen that, in general, since the machinability is excellent when the cutting resistance is 4 kgfcm or less, it can be seen that the higher the content of lead (Pb), the better the machinability. In addition, as can be seen in the graph of FIG. 2B, even when 0.1 to 0.8 wt% of bismuth (Bi) is added, the cutting resistance is 4 kgfcm or less.

In addition, in the case of Example 2 and Comparative Example 6, in which the content of lead (Pb) was the same, Example 6, in which 0.74 wt% of bismuth (Bi) was added, all chip shapes were shear type. It can be seen from Figure 3d and 3e. This result is similar to the case where Bismuth (Bi) is added at 0.5% by weight or less as in Examples 3 to 5, and the brass alloy has a bismuth (Bi) content of 0.1 to 0.5 to have an appropriate cutting resistance. It can be seen that the weight percent is appropriate.

It should be noted that the results of Examples 3 to 5, which are relatively less than Comparative Example 6, in which bismuth (Bi) is added in a relatively high amount, have excellent results in cutting resistance, because of castability and corrosion resistance. It is believed to be due to the influence of tin (Sn) added for the improvement of the aluminum, Al (al) added to improve the castability and mechanical properties, and iron (Fe) added to improve the mechanical strength.

In the case of tin (Sn) added to improve castability and corrosion resistance, it was possible to improve castability by adding 0.6 wt% or less in Examples 3 to 5, but Comparative Example 6 added to 0.2 wt% or less In Essence, the effect was drastically reduced. This can be observed from the experiment in the step mold, which is the fluidity test method of the molten metal, and it was found that 0.1 to 0.5% by weight of the fluidity improvement by the addition of aluminum (Al) was appropriate.

Examples 6, 7 and Comparative Example 7 are examples for determining the content of boron (B) added to refine the grains of brass alloy.

Example 6

57.0-57.5 weight% of copper (Cu), 0.2 weight% or less of lead (Pb), 0.2-0.3 weight% or less of iron (Fe), 0.4-0.5 weight% of tin (Sn), 0.2-0.3 weight% of aluminum (Al), Nickel (Ni) 0.2-0.3 wt%, Bismuth (Bi) 0.3-0.4 wt%, the remainder of brass scrap, copper (Cu) scrap, zinc (Zn) now and The iron (Fe) -copper (Cu) master alloy, tin (Sn), aluminum (Al), and nickel (Ni) bismuth (Bi) are added to the melting furnace and charged into the melting furnace, and the mixture is stirred at 1000 ° C for 30 hours. Heat for a minute to dissolve completely to adjust the chemical composition, then raise the temperature of the furnace to 1090 ℃, hold for 10 minutes, remove the floating non-metallic inclusions in the slag state, lower the temperature of the furnace to 1020 ℃, and boron before tapping (B) 3.5 ppm of powder was formed into agglomerate state, forcedly charged to the bottom of the melting furnace, and maintained for 10 minutes, followed by tapping with a prepared ingot mold to analyze the components. The results are shown in Table 5, and the results of photographing the microstructure with an optical microscope are shown in FIG. 4B.

Example 7

57.0-57.5 wt% of copper (Cu), 0.2 wt% or less of lead (Pb), 0.2-0.3 wt% of iron (Fe), 0.4-0.5 wt% of tin (Sn), 0.2-0.3 wt% of aluminum (Al), nickel (Ni) 0.2-0.3% by weight, Bismuth (Bi) 0.1-0.2% by weight, brass scrap, copper scrap, zinc (Zn) now and iron to produce brass alloys with the remainder zinc (Zn) The (Fe) -copper (Cu) master alloy, tin (Sn), aluminum (Al) and nickel (Ni) bismuth (Bi) is added to the melting furnace and charged into the melting furnace, followed by stirring for 1 hour and 30 minutes. Heated to complete dissolution to adjust the chemical composition, and then the temperature of the melting furnace to 1090 ℃ to maintain for 10 minutes, then remove the non-metallic inclusions in the slag state, lower the temperature of the melting furnace to 1020 ℃ and boron before tapping B) 10ppm powder was formed into agglomerate state, forcedly charged to the bottom of the melting furnace, and maintained for 10 minutes, followed by tapping with a prepared ingot mold for component analysis. The results are shown in Table 5, and the results of photographing the microstructure with an optical microscope are shown in FIG. 4C.

Comparative Example 7

57.0-57.5 wt% of copper (Cu), 0.2 wt% or less of lead (Pb), 0.1-0.2 wt% of iron (Fe), 0.5-0.6 wt% of tin (Sn), 0.2-0.3 wt% of aluminum (Al), nickel (Ni) 0.1 wt% or less, bismuth (Bi) 0.35 to 0.45 wt%, to produce a brass alloy with the balance of zinc (Zn), brass scrap, copper scrap, zinc (Zn) now and iron ( The Fe-copper (Cu) master alloy, tin (Sn), aluminum (Al) and nickel (Ni) bismuth (Bi) is added to the melting furnace and charged into the melting furnace, and stirred at 1000 ° C. for 1 hour and 30 minutes. Heat to complete dissolution to adjust the chemical composition, and then raise the temperature of the melting furnace to 1090 ℃, hold for 10 minutes, remove the non-metallic inclusions in the slag state, lower the temperature of the melting furnace to 1020 ℃ and boron (B before tapping) ) 15ppm powder was formed into agglomerate state, forcedly charged to the bottom of the melting furnace, held for 10 minutes, and then tapped with a prepared ingot mold to perform component analysis. The results are shown in Table 5, and the results of capturing the microstructure with an optical microscope are shown in FIG. 4B.

Figure 4a is a case of Example 5 without the addition of boron (B) is shown a larger grain than in Figure 4b, it can be seen that in the microstructure photographs of Figures 4c and 4d relatively fine grains, Figure When comparing the photograph of FIG. 4C with the photograph of FIG. 4D, since the difference of a grain cannot be detected, the content of boron B does not need to exceed 10 ppm.

TABLE 5

(Unit: weight%)

Corrosion Resistance Evaluation Experiment

The corrosion resistance was evaluated by the international standard ISO-6509 test method, and the corrosion solution was dissolved into distilled water by dissolving 12.7 g of copper chloride (CuCl ₂ · 2H ₂ O) in 1000 ± 10 ml. The sample was exposed by mounting the surface of about 10x10 mm 2 and polished with abrasive cloth # 1200, and then washed with ethyl alcohol. The polished sample was immersed in 250 (+50, -10) ml of corrosion solution per 100 mm 2, corroded for 24 hours at 75 ± 5 ℃ and observed the average corrosion depth with an optical microscope as shown in the photograph of Fig. 5a to 5d It was.

Figure 5a is a corrosion test results of the brass alloy prepared by Comparative Example 6 shows an average corrosion depth of about 300μm, Figure 5b is a corrosion characteristic test results of the brass alloy prepared by Comparative Example 7 average corrosion depth Represents about 400 μm, but in the case of FIGS. 5C and 5D corresponding to Examples 6 and 7, the average corrosion depth is about 150 μm, indicating that the corrosion resistance is excellent.

In the case of the brass alloy of the present invention prepared by containing the content of lead (Pb) as an impurity as described above through Examples 1 to 7 and Comparative Examples 1 to 7 below 0.2 wt%, It can satisfy the standards of the Ministry of Health and Welfare even under the condition of 4% acetic acid solution, which is a severe elution amount of (Pb), and has little leaching of lead (Pb) using brass scrap and copper (Cu) scrap, which are relatively inexpensive raw materials. By manufacturing the brass alloy, the cost of raw materials was reduced, and bismuth (Bi) was added in an amount of 0.1 to 0.5% by weight instead of lead (Pb) to obtain excellent machinability, and 3 to 10 ppm of boron (B) was added. By forming fine grains to produce a higher quality product, while providing a brass alloy for improving the mechanical strength, castability, corrosion resistance, etc., not only industrial machinery parts, but also related to tap water related water, It can be used to replace the roasting meat BBQ plate, such as brass alloy castings for general associated with the plant, environmental pollution, as well as there will be an effect that can be loaded in a brass alloy harmless.

Claims (6)

In the cast brass alloy mainly containing copper (Cu) to zinc (Zn), the brass alloy is 56.0 to 61.0 wt% copper (Cu), 0.1 to 0.5 wt% aluminum (Al1), 0.1 to 0.5 wt% Of iron (Fe), 0.2-0.6% by weight of tin (Sn), 0.15-0.5% by weight of nickel (Ni), 0.20% by weight or less of lead (Pb), workability enhancing additives and grain refinement are added as necessary. , Brass alloy for casting, characterized in that the remainder composed of zinc (Zn). 2. The brass alloy for casting according to claim 1, wherein 0.1 to 0.5% by weight of bismuth (Bi) is added as a workability improving additive. The brass alloy for casting according to claim 1 or 2, wherein 3 to 10 ppm of boron (B) is added as a grain refiner. Brass scrap, copper (Cu) scrap and zinc (Zn) are now used while the content of lead (Pb), which is an impurity, is 0.2% by weight or less, and copper (Cu) is 56.0 to 61.0% by weight and zinc (Zn) It is a residual amount of silver alloy, 0.1 to 0.5% by weight of aluminum (Al) to improve mechanical strength and castability, 0.1 to 0.5% by weight of iron (Fe) to improve mechanical strength, to improve castability and corrosion resistance 0.2-0.6 wt% tin (Sn), 0.15-0.5 wt% nickel (Ni) as an anticorrosion aid, and bismuth (Bi) 0.1-0.5 wt% to improve processability. After charging to 950 ~ 1050 ℃ for 1 to 2 hours to dissolve the planned components, and raise the temperature of the furnace to 1060 ~ 1090 ℃ while maintaining the 5 to 15 minutes by floating the non-metallic inclusions, and again the temperature of the furnace 5 to 15 minutes by loading 3-10 ppm of boron (B) as a grain refiner, to 1000-1050 degreeC After holding method of producing a casting brass alloy according to claim Sikkim the tapping at a temperature of 1000 ~ 1050 ℃. The method of manufacturing a brass alloy for casting according to claim 4, wherein boron (B) is molded into a lump state and charged as a grain refiner. The method of manufacturing a brass alloy for casting according to claim 4, wherein boron (B) is forced into the bottom of the melting furnace as a grain refining agent.