JP6482530B2 - Low lead brass alloy for water supply components - Google Patents

Description

  The present invention relates to a material made of a brass alloy and applied to a water supply member having erosion-corrosion resistance.

  Conventionally, JIS H5120 brass casting CAC203, which has been used for water-related parts such as faucet fittings, contains 0.5 to 3.0% by mass of lead, and has recently been used for water supply parts implemented around the world. It is difficult to meet the lead regulations of copper alloys. Therefore, in order to reduce the influence of harmful lead, production of a copper alloy having a reduced lead content is being studied.

  However, when the lead content is simply reduced, the castability, machinability, and pressure resistance of the copper alloy are reduced, and for example, when used in a valve, water leakage may occur. In order to compensate for such a change in properties due to a decrease in lead, it has been studied to improve cutting performance, dezincification corrosion resistance, and pressure resistance by containing Bi.

  For example, in Patent Document 1 below, Zn is contained together with Zn in an amount of 0.4 to 3.2 mass%, Bi is 0.1 to 4.5 mass%, and P is 0.001 to 0.3 mass%. A brass alloy that suppresses dezincification corrosion and improves mechanical properties and castability while suppressing the content is described.

  Further, in Patent Document 2 below, as a brass alloy that prevents deterioration of water quality and is excellent in machinability and polishability as a plating pretreatment, 0.3 to 1.0% of Sn and 0.5 to 1.0 A brass alloy containing 1% Ni, 0.4-8% Al, 0.01-0.03% P, 1.0-2.0% Bi, and a trace amount of Sb is described. (For example, No. 6, 20). Moreover, the brass alloy in which 5-10 ppm B is further contained by weight ratio in said composition is also described.

  However, in order to ensure machinability, a copper alloy containing a large amount of Bi must be used separately from other copper alloys that do not contain Bi when recycled. This is because, for example, when Bi is mixed into a copper alloy containing Pb, it becomes brittle. The alloy according to Patent Document 1 has Bi because it contains Bi, and the alloy according to Patent Document 2 is also an example of No. 1 in Example. 6 has the same problem.

  On the other hand, a brass alloy that does not contain Bi and is useful as a water supply member from the viewpoint of recyclability is known. For example, Alloy No. 2 which is a comparative example of Patent Document 2. Since 20 does not include Bi, there is no problem that requires discrimination based on the presence or absence of Bi during recycling.

  Patent Document 3 listed below does not contain Bi and Pb as a copper alloy for wire rods, Cu: 62 to 91 mass%, Sn: 0.01 to 4 mass%, and Zr: 0.0008 to 0.045 mass%. And a copper alloy material composed of P: 0.01 to 0.25 mass% and Zn: balance (for example, No. 803). In this copper alloy, in addition to the above-described content range, it is a condition that 62 ≦ Cu−0.5 × Sn−3 × P ≦ 90 is established between the mass% of Cu, Sn, and P. It is said. Furthermore, the total content of the α phase, the γ phase, and the β phase is a phase structure having an area ratio of 95 to 100%, and the average crystal grain size at the time of melt solidification is 0.2 mm or less. Yes. However, when this wire alloy is to be diverted to a water supply member, Bi is not contained, so that the recyclability is sufficient, but the necessary machinability cannot be exhibited.

  Moreover, when using a brass alloy for a water supply member, there is an important problem apart from recyclability. When any brass alloy is used for a water supply member such as a valve, it is exposed to corrosion induced by a rapid flow of water called erosion-corrosion. When the brass alloy is in contact with water that has been left stationary, the metal material surface is gently covered with an oxide film to prevent corrosion, but in an environment exposed to running water, in addition to normal corrosion, The oxide film is destroyed by the influence of shearing force and turbulent flow caused by the flow, and corrosion proceeds. In Comparative Example No. No. 20 alloy has insufficient erosion-corrosion resistance. Examples of brass alloys having such erosion-corrosion resistance include the alloys described in Patent Documents 4 to 6 below.

  Patent Document 4 includes Zn: less than 10 to 25 wt%, P: 0.005 to 0.070 wt%, Sn: 0.05 to 1.0 wt%, Al: 0.05 to 1.0 wt%, and Fe : 0.005 to 1.0 wt%, Pb: 0.005 to 0.3 wt%, any one or two of them in total, 0.005 to 1.3 wt%, with the balance being copper and inevitable impurities A copper alloy having excellent erosion-corrosion resistance is described.

  Patent Document 5 includes Zn: 25 to 40 wt%, P: 0.005 to 0.070 wt%, Sn: 0.05 to 1.0 wt%, Al: 0.05 to 1.0 wt% as essential elements. Furthermore, Fe: 0.005 to 1.0 wt%, Pb: 0.005 to 1.3 wt% in total, any one or two of 0.005 to 1.3 wt% is included, with the balance being copper and unavoidable A copper alloy having excellent dezincification resistance and a crystal grain size of 0.015 mm or less is described.

  Furthermore, in Patent Document 6, Zn: 25 to 40 wt%, P: 0.005 to 0.070 wt%, Sn: 0.05 to 1.0 wt%, Al: 0.05 to 1.0 wt%, Si: 0 0.005 to 1.0 wt% as an essential component, and further, any one or two of Fe: 0.005 to 1.0 wt% and Pb: 0.005 to 0.3 wt% in total amount of 0.005 Copper excellent in dezincification corrosion resistance, characterized by including 1.3 wt% of the alloy composed of copper and inevitable impurities as the balance, and cold rolling at a workability of 3 to 20% after final annealing Alloys are described.

  Furthermore, in the following Patent Document 7, as a copper alloy containing Zr or Te as a trace element, Zn: 8 to 40%, Zr: 0.0005 to 0.04%, P: 0.01 to 0.25% Containing Si: 2 to 5%, Sn: 0.05 to 6% by mass and Al: 0.05 to 3.5% by mass, with the remainder being Cu and inevitable impurities A copper alloy is described. In addition, as Example 105, there is no Si or Bi, Zn: 27%, Sn: 0.8%, Al: 0.8%, P: 0.05%, Pb: 0.18%, Zr: 0 A copper alloy composed of 0.005% and Te: 0.12% is described.

Further, Patent Document 8 below describes an example in which an effect of individual elements is unified by zinc equivalent (Zneq), and an alloy satisfying necessary physical properties is found by satisfying the inequality condition of zinc equivalent Zneq. Yes. However, this is an example including Bi. Specifically, Al: 0.4 to 2.5 mass%, P: 0.001 to 0.3 mass%, Bi: 0.1 to 4.5 mass%, Ni: 0 to 5 0.5% by mass, the contents of Mn, Fe, Pb, Sn, Si, Mg, and Cd are each 0 to 0.5% by mass, contain Zn, and the remainder consists of Cu and inevitable impurities. And it is conditional on content of Zneq and Al satisfying following formula (1) (2).
Zneq + 1.7 × Al ≧ 35.0 (1)
Zneq-0.45 × Al ≦ 37.0 (2)

WO2013 / 145964 A1 JP 2000-239765 A Japanese Patent No. 4094044 JP 60-138034 A JP-A 61-199043 JP 62-30862 A WO2007 / 091690 A1 Japanese Patent No. 5522582

  However, since the alloy according to Patent Document 4 has a small Zn content, the tensile strength is insufficient and a problem occurs in mechanical properties. Further, although erosion-corrosion resistance is claimed in the literature, the Sn content is actually insufficient and the erosion-corrosion resistance is insufficient.

  The alloys according to Patent Documents 5 and 6 have a problem that elongation tends to be insufficient due to a large Zn content, and dezincification corrosion easily occurs. Furthermore, the erosion-corrosion resistance was insufficient.

  Further, since Patent Document 7 contains Zr and Te as essential elements, there is a problem when used in combination with other copper alloys. Since Te is particularly toxic, it was not preferable to use it for water supply components.

  Furthermore, since the alloy of Patent Document 8 contains Bi, it cannot be used by being mixed with other general copper alloys containing Pb during recycling. Also. There was also a problem that the erosion-corrosion resistance was insufficient.

  Therefore, the present invention maintains erosion-corrosion resistance while maintaining the dezincification corrosion resistance necessary as a water supply member, suppressing the use of elements exhibiting toxicity, and ensuring the recyclability by suppressing the Bi content. An object of the present invention is to obtain a brass alloy having excellent mechanical properties as a water supply member.

In the present invention, Zn is 24% by mass or more and 34% by mass or less, Sn is 0.5% by mass or more and 1.7% by mass or less, Al is 0.4% by mass or more and 1.8% by mass or less, and P is 0.005%. Containing not less than 0.2% by mass and not more than 0.01% by mass and not more than 0.25% by mass of Pb, with the balance consisting of copper and inevitable impurities,
When Sn is less than 1.0% by mass, the above-mentioned problem is solved by a low lead brass alloy for water supply members that satisfies the condition of the following formula (3) with respect to the mass% of Al and Sn.
・ Al + 2 × Sn ≧ 2.8 (3)

  A lower Pb is desirable, but even in a limited range that suppresses the effect on health, a small amount contributes to improved machinability. Moreover, Pb and the Al—P compound act as a chip breaker in a composite manner, thereby greatly contributing to improvement in machinability. Thereby, it becomes an alloy suitable for manufacture of a water supply member, ensuring sufficient machinability. Further, by containing a predetermined amount of Sn, the mechanical properties such as tensile strength, elongation, and 0.2% proof stress required as a brass alloy containing a large amount of Zn are exhibited while exhibiting durability against erosion-corrosion. be able to.

  In addition, when Sn is less than 1.0 mass%, in order to ensure erosion-corrosion resistance, it is necessary to satisfy | fill the conditions of said Formula (3) between Al as further conditions. Both Al and Sn are involved in erosion-corrosion resistance. In particular, in an environment where Sn is less than 1.0% by mass, the contribution to erosion-corrosion resistance is doubled with respect to Al. . In order to obtain the necessary physical properties while ensuring the balance of the alloy, the condition of the above formula (3) is ensured. On the other hand, when Sn is 1.0% by mass or more, erosion-corrosion resistance can be sufficiently ensured and 0.2% proof stress is also ensured even if the above formula (3) is not satisfied.

  In addition, although the element which improves machinability similarly has Si, in the brass alloy concerning this invention, it shall be less than the quantity contained as an unavoidable impurity. This is because Si generates an oxide and easily causes a problem in recyclability and mechanical properties, particularly elongation, and may reduce erosion-corrosion resistance.

  Further, as a variation of the brass alloy according to the present invention, when B is further contained in the range of 0.015% by mass or less in addition to the above composition, it greatly contributes to the dezincification corrosion resistance effect.

  Furthermore, as another variation of the brass alloy according to the present invention, in addition to the above-described blending, even when Ni is contained in a range of 1.8% by mass or less, it greatly contributes to the dezincification corrosion resistance effect. .

  According to the present invention, a brass alloy water supply member that secures safety, durability, and convenience, which also secures cutting properties while suppressing recycle by increasing the content of Bi and also has erosion-corrosion resistance, is manufactured. Can do.

It is a schematic diagram of the tensile test evaluation method. It is a conceptual diagram of an erosion-corrosion test apparatus. It is a reference figure of the machinability evaluation method. It is a graph of the erosion-corrosion maximum depth with respect to Sn content in an Example. It is a graph of the erosion-corrosion maximum depth with respect to the value T of Formula (4) in an Example. It is a photograph which shows the cutting powder in a machinability test.

The present invention will be described in detail below.
This invention is a brass alloy for water supply members containing at least Zn, Sn, Al, P, and Pb.

  The Zn content of the brass alloy needs to be 24% by mass or more, and is preferably 27% by mass or more. If it is less than 24% by mass, the tensile strength is insufficient and a problem occurs in the mechanical properties. Moreover, by setting it as 27 mass% or more, 0.2% yield strength can fully be ensured and it becomes a brass alloy excellent in intensity | strength. On the other hand, it needs to be 34% by mass or less, and is preferably 32% by mass or less. If there is too much Zn, the elongation tends to be insufficient. Moreover, when Zn exceeds 34 mass%, dezincification corrosion will become large too much.

  The Sn content of the brass alloy needs to be 0.5% by mass or more, and if it is less than 0.5% by mass, the resistance to erosion-corrosion becomes insufficient. When the content is 1.0% by mass or more, erosion-corrosion resistance can be sufficiently secured, and 0.2% proof stress can be sufficiently secured. On the other hand, it needs to be 1.7% by mass or less, and preferably 1.3% by mass or less. This is because if the amount of Sn is too large, the elongation is too low. Moreover, when Sn is less than 1.0 mass%, in order to ensure erosion-corrosion resistance, it is necessary to satisfy the condition of formula (3) described later in relation to Al.

  The Al content of the brass alloy needs to be 0.4% by mass or more, preferably 0.6% by mass or more. If it is less than 0.4% by mass, the tensile strength and the 0.2% proof stress are insufficient, which causes a problem in mechanical properties. Further, a compound formed with P described later greatly contributes to the machinability, but if Al is insufficient, the effect becomes insufficient. On the other hand, it is necessary to be 1.8% by mass or less, and preferably 1.3% by mass or less. If it exceeds 1.8% by mass, the elongation may decrease too much.

Moreover, when content of Sn is less than 1.0 mass%, it is necessary to satisfy | fill the conditions of following formula (3) about content of Sn and Al. The maximum depth that can be generated by erosion-corrosion tends to be improved by the increase of Al and Sn, but especially in an environment where Sn is less than 1.0% by mass, the erosion-corrosion resistance due to an increase in Sn content. The contribution to improvement appears as a double effect compared to the contribution to improvement of erosion-corrosion resistance due to an increase in Al content.
・ Al + 2 × Sn ≧ 2.8 (3)

  The P content of the brass alloy needs to be 0.005% by mass or more, preferably 0.01% by mass or more. When there is too little P, the effect which the Al-P compound formed between Al contributes to machinability will become thin, and it will become easy to connect cutting powder. Moreover, since P exhibits a deoxidation effect, if it is too small, the deoxidation effect at the time of casting will be reduced, so that gas defects will increase and the molten metal will oxidize and the molten metal flow will be reduced. On the other hand, it needs to be 0.2% by mass or less, and preferably 0.15% by mass or less. When there is too much P, hard Al-P compounds etc. will increase too much and elongation will fall. Furthermore, it reacts with the moisture in the mold, and gas defects and shrinkage defects increase.

  The brass alloy must have a Pb content of 0.01% by mass or more, and preferably 0.03% by mass or more. The presence of Pb contributes to the machinability together with the Al—P compound, but if it is less than 0.01% by mass, the machinability may be insufficient. In particular, since the brass alloy contains Sn and a hard γ phase is formed, contribution of the machinability improving effect by Pb is indispensable. On the other hand, if it exceeds 0.25% by mass, it becomes difficult to satisfy the leaching standard as an alloy for water supply members depending on the region, and therefore the content needs to be 0.25% by mass or less at the maximum.

  In addition to Cu, the brass alloy may contain elements other than those described above as raw materials and inevitable impurities that are inevitably contained due to problems during production. However, it is necessary to keep the content of these elements within a range that does not impair the effects of the present invention. This is because if there are too many unexpected elements, the physical properties may be hindered even in the range of the above elements. The total amount of these inevitable impurities is preferably less than 1.0% by mass, and more preferably less than 0.5% by mass.

  Among the inevitable impurities, the Si content is preferably less than 0.2% by mass, more preferably less than 0.1% by mass, and even more preferably less than the detection limit. If there is too much Si, oxides will be involved, elongation will be reduced, and shrinkage will be promoted, making it impossible to produce a sound casting.

  Among the inevitable impurities, the Bi content needs to be less than 0.3% by mass, preferably less than 0.1% by mass, and more preferably less than the detection limit. This is because if Bi is contained in an amount that cannot be ignored, it must be handled separately when the product is recycled, which makes it difficult to handle. If Bi is contained in an amount exceeding 0.3% by mass, the coexistence with Pb contained in the brass alloy of the present invention results in insufficient elongation, which may cause a problem in mechanical properties.

  The content of the elements that are inevitable impurities is preferably less than 0.4% by mass, more preferably less than 0.2% by mass, and even more preferably less than the detection limit. Examples of such impurities include Fe, Mn, Cr, Zr, Mg, Ti, Te, Se, and Cd. Among these, Se, Cd, and Te, which are known to be toxic, are desirably less than 0.1% by mass, and more desirably less than the detection limit. Further, Zr for increasing shrinkage defects is desirably less than 0.1% by mass, and more desirably less than the detection limit.

  On the other hand, when the brass alloy contains 0.0005% by mass or more of B as an element to be intentionally contained separately from the inevitable impurities, the dezincification corrosion resistance is greatly improved. This is because the crystal grains are refined by B and become a shape that is hardly subject to dezincing corrosion. When B is contained in an amount of 0.0007% by mass or more, dezincification corrosion resistance is further improved, which is preferable. On the other hand, if it exceeds 0.015% by mass, a large amount of a hard compound is generated in the structure, which may adversely affect the machinability and elongation.

  Moreover, the brass alloy may contain Ni as an element to be intentionally contained separately from the inevitable impurities. When Ni is contained in an amount of 0.1% by mass or more, the dezincification corrosion resistance of the brass alloy is improved by increasing the area of the α phase having excellent corrosion resistance. This effect can be overlapped with the effect of the B content. On the other hand, it is preferable that it is 1.8 mass% or less, and it is more preferable in it being 0.5 mass% or less. When Ni is added excessively, the phase with a large amount of Sn increases, so that elongation and machinability are likely to deteriorate. When Ni exceeds 1.8% by mass, a decrease in elongation cannot be ignored. In order to reliably suppress the decrease in elongation, the content is preferably 0.5% by mass or less.

  In addition, you may add both B and Ni in the range of said content as an element intentionally contained in the said brass alloy.

  In addition, the value of content in this invention shows content in the time of manufacturing an alloy by casting, forging, etc. instead of the ratio in a raw material.

  The remainder of the brass alloy is Cu. The brass alloy concerning this invention can be obtained with the manufacturing method of a general copper alloy, and when manufacturing a water supply member with this brass alloy, a general manufacturing method (for example, casting, copper drawing, forging, etc.) Can be manufactured. For example, there is a method in which an alloy is melted using a heavy oil furnace, a gas furnace, a high frequency induction melting furnace, etc., and cast into a mold of each shape.

  Hereafter, the example which actually manufactured the brass alloy concerning this invention is given and reported. First, the test method performed with respect to a brass alloy is demonstrated.

<Tensile test method>
A sample cast in a φ28 mm × 200 mm mold was processed into a 14A test piece defined by JIS Z2241. The specific shape is as shown in FIG. This is a proportional test piece in which the original cross-sectional area S ₀ of the parallel portion and the original point distance L ₀ are in a relationship of L ₀ = 5.65 × S ₀ ^ (1/2). The diameter d _{0 of the} rod-shaped portion was 4 mm, the original point distance L ₀ was 20 mm, the columnar parallel portion length L _c was 30 mm, and the shoulder radius R was 15 mm. (L ₀ = 5.65 × (2 × 2 × π) ^ (1/2) = 20.04)

About this test piece, the tensile test was implemented based on JISZ2241, and the tensile strength (MPa), 0.2% yield strength (MPa), and elongation (%) were evaluated as follows. The tensile strength was the maximum test force Fm that the test piece withstood during the test until it showed a discontinuous yield in the test. 0.2% proof stress, the plastic elongation, a stress when becomes equal to 0.2% relative to the original gauge length _{L 0.} Further, the elongation is a value expressed as a percentage of permanent elongation of the test piece after testing to failure to the original gauge length L _0.
-Evaluation of tensile strength was made into "Good" (G) ... 300MPa or more, "Fair" (F) ... 250MPa or more and less than 300MPa, "Insufficient" (I) ... less than 250MPa.
The evaluation of 0.2% proof stress was “Good” (G): 100 MPa or more, “Fair” (F): 80 MPa or more and less than 100 MPa, “Insufficient” (I): less than 80 MPa.
・ Evaluation of elongation was “Good” (G): 25% or more, “Fair” (F): 20% or more and less than 25%, “Insufficient” (I): less than 20%.

<Erosion-corrosion test>
As shown in FIG. 2, a sample cast into a φ20 × 120 mmL mold is processed into a cylindrical shape of φ16 mm as a test piece 12, and a gap of 0.4 mm is formed with respect to this test piece 12. A nozzle 11 having a diameter of 1.6 mm was set, and a 1% CuCl ₂ aqueous solution 13 was continuously flowed from the nozzle 11 toward the sample at a flow rate of 0.4 L / min for 5 hours, and the weight loss (depletion amount) of the sample before and after the test. And the maximum depth was measured.
・ Evaluation of the amount of wear was “Good” (G): less than 250 mg, “Fair” (F): 250 mg or more and less than 350 mg, “Insufficient” (I): 350 mg or more.
・ Evaluation of maximum depth of erosion-corrosion was “Good” (G): 150 μm or less, “Fair” (F): deeper than 150 μm and 200 μm or less, and “Insufficient” (I): deeper than 200 μm.

<Perforation test>
Each alloy was subjected to a drilling test using a drilling machine. In the drilling test, each test material was machined to φ18 mm × 20H, and evaluation was performed using the drilling machine under the drilling conditions shown in Table 1. The evaluation method measures the time required for drilling 5 mm, and evaluates “Good” (G) for 20 sec or less, “Fair” (F) for more than 20 sec and 25 sec or less, and “Insufficient” (I) for more than 25 sec. did.

<Lathe processing test>
About the alloy to be tested, a sample cast in a φ28 × 200 mm mold is fed by a general-purpose lathe using a carbide brazing tool, and dry cutting is performed at 0.15 mm / rev and a rotational speed of 550 rpm. Obtained. As shown in FIG. 3, the evaluation method of the cutting powder was classified according to the shape, and a good one (“Good” (G)) and a poor one (“Insufficient” (I)) were determined.

<Dezincification corrosion test method>
A sample cut into a 10 mm square cube from a sample cast in a φ28 mm × 200 mm mold was used as a test piece, and the test was performed in accordance with ISO 6509. That is, the periphery of the test piece was covered with an epoxy resin having a thickness of 15 mm or more, and only one surface of the test piece was exposed from the resin. The exposed surface 100 mm ² was polished with wet polishing paper, finished with 1200 polishing paper, and washed with ethanol immediately before the test. The sample embedded in the epoxy resin and exposed only on one side was immersed in 250 mL of a 12.7 g / L cupric chloride aqueous solution at 75 ± 5 ° C. for 24 hours. After completion of the test, it was washed with water, rinsed with ethanol, and immediately, the dezincing depth of the cross section was measured using an optical microscope. Specifically, the sample 10 mm is divided into 5 fields of view, and the dezincification depth for each field of view is measured at the minimum point and the maximum point, and the average value of 10 points in total is the dezincification corrosion average depth. Of the 10 points, the depth of the deepest point was evaluated as the maximum dezincification corrosion depth as follows. Any of those results that were not x were considered acceptable.
・ Evaluation of the average depth of dezincification corrosion is “Very Good” (V): less than 50 μm, “Good” (G): 50 μm to less than 100 μm, “Fair” (F): 100 μm to less than 200 μm, “ Insufficient ”(I): 200 μm or more.
・ Evaluation of maximum dezincification corrosion depth is “Very Good” (V): less than 100 μm, “Good” (G): 100 μm or more and less than 200 μm, “Fair” (F): 200 μm or more and less than 400 μm, “ Insufficient "(I) ... 400 μm or more.

<Sample production method>
The materials constituting each element were mixed, melted in a high frequency induction melting furnace, and then cast to prepare test materials in each example having the contents shown in each table. In addition, all the values of content are the mass%, and are the measured values after manufacture. The following tests were performed on each obtained copper alloy. In all the examples in the table, Sb, Si, and Fe were less than the detection limit. In addition, elements not described in the table and blanks indicate that they are below the detection limit.

  First, the contents of the above formula (3) were confirmed by changing the contents of Sn and Al. Table 2 shows the components used for the evaluation, the mechanical properties, and the results of the erosion-corrosion (EC) test. FIG. 4 shows the results plotted as a line graph for each Al concentration with the horizontal axis representing the value of Sn and the vertical axis representing the maximum erosion-corrosion depth. In addition, Test Examples 1-4 are examples of Al: 0.6 mass%, Test Examples 5-8 are Al: 1.0 mass%, and Test Examples 9-12 are Al: 1.7 mass%. Each group arranges an example in the order of increasing the amount of Sn.

  As a result of the test, the erosion-corrosion (EC) in the region where the Sn content is 1.0% by mass or more, compared to the example in which the Sn content is less than 1.0% by mass, regardless of the Al content. ) Maximum depth has been shown to improve particularly. Further, it was shown that when the Sn content is the same, the maximum erosion-corrosion depth is improved as the Al content is increased. However, it has been shown that the tendency is particularly prominent in the region where the Sn content is less than 1.0% by mass.

  Therefore, among the above examples, an example in which Sn is less than 1.0% by mass was examined. That is, Table 3 shows samples extracted from Test Examples 1 and 2 in which Al is 0.6% by mass, Test Examples 5 and 6 in which Al is 1.0% by mass, and Test Examples 9 and 10 in which Al is 1.7% by mass. Shown in Among these, the erosion-corrosion maximum depth was “Insufficient” in Test Examples 1, 2, and 5. Compared to Test Example 1, Test Example 2 has a Sn content higher by about 0.2% by mass. Further, Test Example 5 is higher in Al content by about 0.4% by mass than Test Example 1. In Test Example 2 and Test Example 5, the value of the maximum erosion-corrosion depth is almost the same. That is, in comparison with Test Example 1, Test Example 2 in which the Sn content increased by 0.2% and Test Example 5 in which the Al content increased by 0.4% were the test examples at the maximum erosion-corrosion depth. The decrease from 1 is equal. From this, in the region where Sn is less than 1.0% by mass, the Sn content contributes to the improvement of the erosion-corrosion resistance due to the decrease in the maximum erosion-corrosion depth due to the increase in the Sn or Al content. The increase effect is presumed to be twice that of the Al content increase effect. From this, the number T according to the following formula (4) can be used as an index of erosion-corrosion resistance.

  T = Al + 2 × Sn (4)

FIG. 5 is a graph plotting the data in Table 3 above, with the value of equation (4) on the horizontal axis and the value of maximum erosion-corrosion depth on the vertical axis. As a result of plotting, in the range where the value T of the equation (4) is less than 2.8, the maximum erosion-corrosion depth showed a decreasing tendency almost linearly as the value of the equation (4) T increased. Further, in the range where the value T of the formula (4) is 2.8 or more, the maximum erosion-corrosion depth tends to be almost constant. From this, it was confirmed that when the Sn content is less than 1.0 mass%, the erosion-corrosion resistance can be sufficiently ensured by satisfying the condition of the above formula (3).

  Among the above test examples, Test Examples 3, 4, 6 to 12 correspond to examples of the alloys according to the present invention. Among these, Test Examples 6, 9, and 10 correspond to the examples in which Sn is less than 1.0% by mass and satisfies the condition of T ≧ 2.8. On the other hand, Test Examples 3, 4, 7, 8, 11, and 12 satisfy the condition that Sn is 1.0 mass% or more, and correspond to Examples.

  Next, changes in mechanical properties and erosion-corrosion resistance when the contents of Zn, Al, P, Sn, and Pb were changed were evaluated by a tensile test and an erosion-corrosion test. Table 4 shows the components and results.

  First, an example in which the Zn content was changed was prepared. Comparative Example 1 in which Zn is less than 24% by mass has a problem in tensile strength. In Example 1 which is 24% by mass or more, the tensile strength can be secured to some extent, and in Examples 2 and 3 which are 27% by mass or more, sufficient tensile strength can be secured. On the other hand, in Comparative Example 2 in which Zn is too much and exceeds 34% by mass, a problem occurs in elongation.

  Secondly, an example in which the Al content was changed was prepared. In Comparative Example 3 where Al was less than the detection limit, both the tensile strength and the 0.2% proof stress were insufficient. In Example 4 in which Al is 0.39% by mass, tensile strength and 0.2% proof stress can be secured to some extent, and in Examples 5, 3, and 6 in which Al is 0.6% by mass or more, sufficient Tensile strength and 0.2% yield strength can be secured. On the other hand, in Comparative Example 4 in which Al is too much and exceeds 1.8% by mass, there is a problem in elongation, and in Example 6 of 1.66% by mass which is less than 1.8% by mass, a certain amount of elongation occurs. It has been secured.

  Third, an example in which the P content was changed was prepared. In Example 8 in which P is slightly large, the erosion-corrosion resistance was slightly lowered. Furthermore, in Comparative Example 5 in which P is large and exceeds 0.2% by mass, the elongation is too low.

  Fourth, an example in which the Sn content was changed was prepared. In Comparative Example 6 in which Sn is 0.11% by mass and Comparative Example 7 in which Sn is 0.31% by mass, the erosion-corrosion resistance is insufficient and both the weight loss and the maximum depth are problematic. Value. In Example 9 where Sn was 0.91% by mass and T = Al + 2 × Sn = 2.82, erosion-corrosion resistance could be secured to some extent. Furthermore, in Examples 3 and 10 where Sn was 1.0% by mass or more, sufficient erosion-corrosion resistance could be secured. On the other hand, in Comparative Examples 8 and 9 where Sn exceeds 1.7% by mass, the elongation is too low. In Example 10 where Sn is 1.54% by mass, a certain degree of elongation can be secured.

  Fifth, an example in which the content of Pb was changed was prepared. In the range of Examples 11, 3 and 12, both the mechanical properties and the erosion-corrosion resistance were good. However, in Example 12 where Pb was close to 0.25% by mass, a slight decrease in elongation was observed.

<Machinability evaluation for P and Pb>
It was then evaluated by drilling test and turning test cutting of the change in case of adjust the content for P and Pb. The components and results are shown in Table 5.

  First, the difference due to changes in P is verified. Example 13 in which P was 0.009% by mass and Comparative Example 10 in which P was less than the detection limit were prepared. A perforation test was conducted on these, Examples 7, 3 and 8, and Comparative Example 5 described above. In Comparative Example 10 where P is less than the detection limit, it took too much time, and chips were connected. In Examples 13, 7, and 3 containing 0.005% by mass or more of P, perforation was completed in a sufficiently short time. Moreover, the chips obtained in Examples 13 and 3 are divided. This is considered to be because the Al—P compound formed by containing P works as a chip breaker during cutting. On the other hand, in Example 8 and Comparative Example 5 in which P exceeds 0.1% by mass, the time required for perforation becomes slightly longer and cannot be ignored.

  Further, Comparative Example 10, Example 13, and Example 3 were evaluated by the shape of the cutting powder. The photographs are shown in FIGS. 6A, 6B, and 6C, respectively. In Comparative Example 10, a problematic cutting powder connected in a helical shape was generated, but in Example 13 in which P was increased, the cutting powder was shortened as a whole, and in Example 3 in which P was increased, further cutting powder was generated. It became short and excellent.

  Next, the difference due to the change in Pb is verified. Comparative Example 11 in which Pb was newly below the detection limit was prepared. A drilling test was conducted on these and Examples 11, 3, and 12 described above. In Comparative Example 11 in which Pb was less than the specified value, the perforation time was significantly increased. In Example 11 in which Pb was 0.025% by mass, the machinability could be ensured by suppressing the drilling time to some extent. In Examples 3 and 12 with more Pb, the drilling time was sufficiently shortened. Further, Comparative Example 11 and Example 11 were evaluated by the shape of the cutting powder. The photograph of the cutting powder of the comparative example 11 and Example 11 is shown to each of FIG.6 (d), (e). In any case, the shape of the cutting powder was satisfactory.

  Further, Comparative Example 12 was prepared as an example not containing both P and Pb. About this comparative example 12, the evaluation by the shape of cutting powder and the drilling test were done. A photograph of the cutting powder is shown in FIG. As a result, since Comparative Example 12 does not contain P and Pb, the cutting powder produces a problematic cutting powder that is connected for a longer time than Comparative Example 10 containing only Pb. It has become a long time.

  In addition, we will examine examples for each case. The data is shown in Table 6.

<Results of dezincification corrosion test>
It was verified using Example 2, Example 3, and Comparative Example 2 how the depth of dezincification corrosion changes due to the difference in Zn. In Example 2 where the amount of Zn was sufficiently small, an excellent value was shown, and even in Example 3, there was little corrosion. On the other hand, in Comparative Example 2 where Zn exceeds 34% by mass, the maximum depth is close to the allowable limit, and the average depth is significantly deteriorated.

<Verification of behavior by addition of Bi>
When Comparative Example 13 containing 0.35% by mass of Bi was prepared with a composition close to that of Example 3, the elongation was greatly reduced, and it was confirmed that there was a problem not only from recyclability but also from mechanical properties. .

<Verification of behavior by addition of Ni-1>
Example 14 was prepared by adding 0.82% by mass of Ni, and Comparative Example 14 by adding 1.88% by mass of Ni in the same manner as in Example 3. In both Example 14 and Comparative Example 14, the dezincification corrosion resistance was greatly improved, but in Comparative Example 14 containing 1.88% by mass of Ni, the elongation was too low.

<Verification of behavior by addition of Ni-2>
Examples 15 and 16 in which Sn was reduced and Pb was increased as compared with Example 14 were prepared. The anti-dezincing corrosion resistance of Example 16 with more Ni than Example 15 was further improved. Further, when the erosion-corrosion resistance was measured for Examples 15 and 16, both showed good results. However, in Example 16, a certain degree of elongation could be secured, but it was also shown that it slightly decreased.

<Verification of behavior by addition of B-1>
Example 17 was prepared with a formulation close to that of Example 3 and further adding 0.006% by mass of B. In both cases, the dezincification resistance was greatly improved.

<Verification of behavior by addition of B-2>
Examples 18 to 20 were prepared with a formulation close to that of Example 3 and an increased amount of B added. The B content in Example 18 is 0.0007% by mass, the B content in Example 19 is 0.0012% by mass, and the B content in Example 20 is 0.011% by mass. The dezincification corrosion resistance was particularly improved as the amount of B increased, and the dezincification corrosion resistance of Example 20 was particularly excellent. However, in Example 20, it was also shown that a certain degree of elongation could be ensured but would decrease.

<Verification of behavior by addition of B and Ni>
Examples 21 to 23 were prepared by adding both B and Ni in a formulation similar to Example 3. All of them exhibited particularly excellent values for dezincification corrosion resistance. However, it was also shown that in some examples, a certain degree of elongation could be ensured but it would decrease.

11 Nozzle 12 Test piece 13 CuCl ₂ aqueous solution

Claims (3)

Zn is 24% by mass to 34% by mass, Sn is 0.5% by mass to 1.7% by mass, Al is 0.4% by mass to 1.8% by mass, and P is 0.005% by mass to 0 %. .15 wt% or less, the Pb containing 0.25 wt% or less than 0.01 wt%, the low-lead brass alloy for tap member ing from the balance copper and inevitable impurities.
However, when Sn is less than 1.0 mass%, the condition of the following formula (1) is satisfied with respect to Al and Sn mass% .
・ Al + 2 × Sn ≧ 2.8 (1) The low lead brass alloy for water supply members which contains B in addition to 0.0005 mass% or more and 0.015 mass% or less in addition to the mixing | blending of the copper alloy for water supply members of Claim 1 . The low lead brass alloy for water supply members which contains 0.1 mass% or more and 1.8 mass% or less of Ni further in addition to the mixing | blending of the copper alloy for water supply members of Claim 1 or 2 .

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