JP5416323B1 - Brass alloy for water supply components - Google Patents

Abstract

A brass alloy for water supply members that is easy to manufacture is obtained by reducing the number of main components whose contents must be controlled. Ni is contained in an amount of 0.3 to 5.5% by mass, P is contained in an amount of 0.01 to 0.5% by mass, Bi is contained in an amount of 0.1 to 5.0% by mass, and Zn is contained. It is based on a brass alloy in which the contents (mass%) of Zn and Ni satisfy the following two formulas (1) and (2), and the balance is copper and trace elements.
Zn + 2.2 × Ni ≧ 32.5 (1)
Zn-1.3 × Ni ≦ 38.6 (2)

Description

  The present invention relates to a brass alloy containing zinc, and in particular, to a brass alloy for water supply members used in a water supply path or the like.

  A copper alloy containing 20 to 40% zinc is called brass or brass, which has excellent castability, ductility, and machinability, and also has a lustrous appearance similar to gold, and is used for various purposes. ing. For example, Patent Document 1 discloses that tin is 0.3 to 1.0%, nickel is 0.5 to 1.0%, aluminum is 0.4 to 8%, phosphorus is 0.01 to 0.03%, A brass alloy containing 1.0 to 2.0% bismuth and having a total of tin, nickel and aluminum phosphorus of 1.5% or more is described.

JP 2000-239765 A

  However, the brass alloy described in Patent Document 1 is composed of a balance of three components of tin, nickel, and aluminum in addition to the amount of zinc, and has many main components, including depletion of zinc during actual production. There was a problem that quality control was difficult.

  Therefore, the present invention reduces the types of main components, facilitates quality control during production, suppresses dezincing corrosion, has excellent mechanical properties, machinability, castability, and excellent versatility. The purpose is to obtain an alloy.

In the present invention, Ni is contained in an amount of 0.3 to 5.5% by mass, P is contained in an amount of 0.005 to 0.5% by mass, and Bi is contained in an amount of 0.1 to 5.0% by mass. Together with Zn,
The content (mass%) of Zn and Ni satisfies the following two formulas (1) and (2),
The above problem was solved by a brass alloy whose balance is copper and trace elements.
Zn + 2.2 × Ni ≧ 32.5 (1)
Zn-1.3 × Ni ≦ 38.6 (2)

  The feature of the present invention is that the necessary physical properties are achieved in a wide Zn content range by the balance between Ni and P while excluding Sn and Al or Sn intentionally. Ni exhibits an effect of preventing dezincification corrosion by dissolving with copper. For this reason, by containing Zn in a range corresponding to the amount of Ni, the dezincification corrosion suppressing effect was sufficiently exhibited, and the effect was reinforced by P and Bi. However, if P and Bi are excessive, the mechanical properties deteriorate, so the range is limited.

  In addition, the brass alloy according to the present invention may contain other trace elements as long as the above dezincification corrosion performance and mechanical properties are not impaired. Specific examples of the trace element include elements other than those described above having at least each content of less than 1.0% by mass. For example, elements such as Sn, Si, Fe, Mn, Mg, Pb, Cd, and Se that can be mixed as impurities can be used. These elements may be difficult to avoid mixing from the raw materials in the production of the alloy. However, the smaller the content, the better the effects of the present invention. In addition, elements that may cause harm when the amount of elution is large, such as Pb, Cd, and Se, are preferably as small as possible regardless of physical properties such as mechanical properties and dezincification corrosion resistance, and are less than the detection limit. It is desirable to be.

  Furthermore, when the brass alloy according to the present invention contains B in the range of 0.15% by mass or less in addition to the above components, the dezincification corrosion resistance is further improved and the mechanical properties are also suitable. Therefore, it is preferable.

  Furthermore, in order to further improve the tensile strength, the brass alloy according to the present invention may contain Al in the range of 1.0% by mass or less in addition to the above components.

  According to the present invention, a brass alloy having a high dezincification corrosion-inhibiting effect and excellent mechanical properties, etc., in which a suitable physical property cannot be obtained unless rigorously prepared for a large number of components in the past. Can be manufactured.

Schematic diagram of test pieces used in the examples Cross-sectional conceptual diagram of dezincing depth The graph which plotted the evaluation result with respect to content of Ni and Zn in an Example 100 times cross-sectional photograph of the sample of Comparative Example 9 in which Zn is excessive 200-fold cross-sectional photograph of the sample of Example 22 200 times cross-sectional photograph of the sample of Comparative Example 11 containing no P 200 times cross-sectional photograph of the sample of Comparative Example 14 containing no Bi

  The present invention will be specifically described below. The present invention is a brass alloy containing at least Ni, P, Bi and Zn. Dezincification corrosion is suppressed mainly by addition of Ni and supplementarily P and Bi.

  The brass alloy according to the present invention contains 0.3% by mass or more of Ni. By containing Ni, there is an effect that mechanical properties such as tensile strength and anti-dezincing corrosion resistance are improved. This effect is considered to appear when Ni dissolves in Cu. However, when the solid solution amount of Ni increases excessively, gas absorption and the like increase, and the castability deteriorates due to generation of gas defects and shrinkage cavities. For this reason, the content of Ni needs to be 5.5% by mass or less, and is preferably 4.5% by mass or less. Moreover, in the brass alloy concerning this invention, content of Ni is prescribed | regulated also in relation with Zn mentioned later.

  The brass alloy concerning this invention needs to contain 0.005 mass% or more of P, and when it contains 0.03 mass% or more, it is preferable. When P is contained, even a slight amount greatly contributes to dezincification corrosion resistance. If it is less than 0.005% by mass, this effect tends to be insufficient. On the other hand, the P content needs to be 0.5% by mass or less, and is preferably 0.25% by mass or less. Exceeding 0.25% by mass tends to cause some problems in elongation, and exceeding 0.5% by mass not only tends to cause problems in tensile strength, but also tends to cause shrinkage. Prone to various problems.

  The brass alloy according to the present invention needs to contain 0.1 mass% or more of Bi, and preferably contains 0.3 mass% or more. Bi is finely dispersed in the alloy to dramatically improve the machinability and exhibit anti-dezincing corrosion resistance. However, if it is less than 0.1% by mass, these effects become insufficient. End up. On the other hand, if there is too much Bi, not only the dezincification corrosion resistance is lowered, but also the mechanical properties are liable to be lowered, so it is necessary to be 5.0% by mass or less, and 4.0% by mass. % Or less is preferable.

  The brass alloy according to the present invention may contain other trace elements in addition to the above elements. Other trace elements are at least less than 0.5% by mass, and include elements other than those described above. For example, Sn, Mn, Fe, Pb, Si, Mg, Cd, Se, etc. are mentioned. Among these, Sn, Mn, Fe, Si, Mg, and Pb are derived from the raw material and easily mixed as impurities. However, since there is a possibility that the effect of the present invention may be inhibited even if there is too much each, it is necessary to keep the content within a range not inhibiting the effect of the present invention.

  Particularly in the brass alloy according to the present invention, the content of Sn as a trace element (impurity) needs to be less than 0.3% by mass, and preferably less than 0.1% by mass. The brass alloy according to the present invention makes it easy to produce a stable quality alloy by reducing the number of main components that determine quality, and it is difficult to balance with other components when Sn is excessively contained. Become. Specifically, when it is 0.3% by mass or more, dezincification corrosion resistance is liable to be reduced, and it becomes difficult to balance the entire alloy. In order to stabilize the quality during production, the smaller the Sn content, the better.

  The content of elements other than Sn may be less than 0.5 mass% per element, and is preferably less than 0.3 mass%. Of these, Pb is relatively easy to mix, but it is desirable to avoid mixing as much as possible, preferably less than 0.3% by mass, and more preferably less than 0.1% by mass. Furthermore, Cd and Se are harmful per se, and if they are used in a large amount for water supply components, these components may be dissolved in water. Therefore, the amount is preferably less than 0.1% by mass and contained as an inevitable impurity. The following is more preferable, and it is most preferable that it is less than the detection limit. In addition, other trace elements including Sn are preferably contained as inevitable impurities in order to exhibit the effects of the present invention more stably.

  The brass alloy according to the present invention may contain B in addition to the above elements. By containing 0.001% by mass or more of B, the mechanical properties and the dezincification corrosion resistance can be further improved from the brass alloy having the compounding ratio specified above. Preferably, it is 0.002 mass% or more. However, when B is excessive, intermetallic compounds derived from B increase, shrinkage cavities frequently occur, castability that can be obtained for products for water supply members is lost, and dezincification corrosion resistance is also reduced. Therefore, the content of B is preferably 0.150% by mass or less, more preferably 0.100% by mass or less, and further preferably 0.050% by mass or less.

  The brass alloy according to the present invention may contain Al in addition to the above elements. By containing 0.2% by mass or more of Al, the tensile strength can be further improved from the brass alloy having the compounding ratio specified above. However, when Al is excessive, dezincification corrosion resistance and elongation decrease, so the Al content is preferably 1.0% by mass or less, and more preferably 0.8% by mass or less.

  The amount of Zn contained in the brass alloy according to the present invention is specified together with the above-described Ni content. Zn may cause dezincification corrosion instead of improving mechanical properties. When Zn is used alone, the range in which the balance between mechanical properties and dezincification resistance is good is extremely narrow. There's a problem. However, when Ni is contained, the range in which the balance can be secured with respect to the Zn content can be expanded, and there is an effect of reducing the difficulty in manufacturing the brass alloy according to the present invention. The allowable range of Zn spread by this effect appears as the following inequalities (1) and (2). This indicates that the allowable range in which Zn can exist increases as the amount of Ni increases. That is, if the Zn content deviates from the condition of formula (1) and is small, the tensile strength becomes insufficient, but if Ni is large, the shortage of Zn can be compensated accordingly. However, if the tensile strength is ensured more reliably, the Zn content is preferably 33% by mass or more. On the other hand, if the Zn content is large and deviates from the condition of the formula (2), the dezincification corrosion resistance becomes insufficient, but if Ni is large, the influence of the increase in Zn can be suppressed accordingly. . However, it is preferable to satisfy the following inequality (3) in order to ensure dezincification corrosion resistance more reliably.

Zn + 2.2Ni ≧ 32.5 (1)
Zn-1.3Ni ≦ 38.6 (2)
Zn-0.5Ni ≦ 38.8 (3)

  The brass alloy according to the present invention can be used for casting in which it is melted and poured into a mold, and particularly when it is used for a die casting product, the effect can be suitably exhibited. Moreover, you may use for a forging, a wrought copper product, etc. In any case, it is possible to suppress the formation of β-phase where dezincification is likely to proceed, but even if the crystal structure is likely to change, the mechanical properties and machinability of the material are ensured within the above blending ratio range. However, elution and dezincification corrosion can be suppressed.

  Furthermore, since the brass alloy according to the present invention excludes Sn from the main components for which the blending ratio must be adjusted in manufacturing, even if it is manufactured by casting in which strict quality control is difficult at the time of manufacturing, as intended It is easy to manufacture products with the necessary characteristics such as anti-dezincing corrosion resistance and mechanical properties.

  The Example which specifically mix | blended the brass alloy concerning this invention is given. First, the evaluation method will be described.

<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. 1, and a proportional test piece in which the original cross-sectional area S ₀ of the parallel portion and the original gauge point distance L ₀ have a relationship of L ₀ = 5.65 × S ₀ ^ (1/2). It is. 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 tension test was implemented based on JISZ2241, and the tensile 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. Further, the elongation is a value representing the permanent elongation of the test piece after being tested until it breaks as a percentage of the original score distance.
-Evaluation of tensile strength was made into (circle) ... 300MPa or more, (triangle | delta) ... 250MPa or more and less than 300MPa, x ... less than 250MPa. In the table below, the item is displayed as “Draw” and the unit is omitted.
・ Evaluation of elongation was as follows: ○ …… 30% or more, Δ …… 20% or more but less than 30%, × …… less than 20%. In the table below, the item is displayed as “stretched” and the unit is omitted.

<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, after washing with water and rinsing with ethanol, the dezincing depth of the cross section immediately (in Fig. 2, the part that was further dezincified and corroded from the corroded surface excluding the corrosion depth A of the entire surface) B depth (μm) 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.
-Dezincification corrosion average depth: ○: Less than 200 μm, x: 200 μm or more. In the table below, the item is indicated as “flat”.
・ Maximum depth of dezincification corrosion: ○ …… less than 200 μm, Δ …… 200 μm or more and less than 400 μm, × …… 400 μm or more. In the table below, the item is indicated as “Most”.

<Castability test>
In order to use it as a castability test in the mechanical property test and dezincification corrosion test described above, the influence on the workability and product is explained from the flowability of the molten metal and its product structure when casting into a φ28mm × 200mm mold. It was evaluated as follows.
・ Evaluation of castability: ○ …… Can be cast without problems, △ …… Slightly adversely affects the product due to deterioration of workability, gas defects, and shrinkage, but no fatal defects, × …… Work The product was adversely affected by deterioration of properties, gas defects and shrinkage nests, making it unsuitable as a brass alloy for water supply components.

  About the Example and Comparative Example of the present invention, after melting at each compounding ratio, the sample was melted by casting, and the content of each element of the sample and the results of the above test were combined, and the following: Shown in each table. Here, the content of Cu is obtained by subtracting the sum of the contents of each element other than Cu from 100% by mass, and “Expression 1”, “Expression 2”, and “Expression 3” are the above inequalities (1) to ( The value of each left side of 3) is shown. Examples are extracted from these examples and comparative examples, and each component is verified. “Comprehensive” as used herein refers to comprehensive evaluation (hereinafter referred to as “comprehensive evaluation”) for evaluating whether it is suitable as a brass alloy for water supply members. The above-mentioned mechanical property test, dezincification corrosion test, and castability In the test, all of the evaluations of “◯” were evaluated as “◯”, those including Δ evaluation but not including “×” evaluation were evaluated as “×”, and those including even one “×” were determined as “×”.

  First, Table 1 lists comparative examples and examples in which the contents of Al, Sn, and Si were set below the detection limit and the amounts of Ni, Bi, P, Zn, and Cu were prepared. Among these, Comparative Examples 1-3 has Ni content less than a detection limit. As a result, although Comparative Example 1 satisfies Equation 1, it is considered that the tensile strength is insufficient because Ni is not present. On the other hand, in Comparative Examples 2 and 3, Zn is excessively deviating from the allowable range of Zn in the state where Ni is not present even though Equation 2 is satisfied. It seems that ease has been demonstrated as it is. That is, Comparative Examples 1 to 3 indicate that it is difficult to balance the alloy performance in the situation where there is no Ni.

  In Comparative Examples 4 to 9, Ni is gradually increased. Of these, Comparative Examples 4, 5, and 8 do not satisfy Formula 1, and the evaluation of the tensile strength is x. In Comparative Example 8, the evaluation is also reduced to Δ because the Zn is too little. . On the other hand, in Comparative Examples 6, 7, and 9 that do not satisfy Formula 2, the evaluation of dezincification corrosion is x. On the contrary, in Comparative Example 10, Ni was excessive and all of the formulas 1 to 3 were satisfied. However, there was a slight problem in castability, and the tensile strength was lowered due to the formation of shrinkage cavities.

  Examples 1 to 10 include evaluation of Δ in part. Of these, Examples 1, 3, 6, 9, and 10 that satisfy Expression 2 but do not satisfy Expression 3 have an evaluation of the maximum dezincing depth of Δ, and Expression 3 is sufficient to suppress dezincing corrosion sufficiently. It was shown that it is more desirable to satisfy the conditions. On the other hand, Examples 2, 4, 5, 7, and 8 satisfy Formula 1, but the content of only Zn itself is slightly less than 33% by mass, so that there is a slight problem in tensile strength, and Δ. . In Examples 8 to 10, since the amount of Ni is slightly higher and exceeds 4.5% by mass and close to 5% by mass, the gas absorption is increased due to the influence of Ni that is a solid solution of Ni in Cu. It is thought that a gas defect or shrinkage nest has occurred in the part. In Examples 11 to 25, data obtained as a good result are arranged in order of Ni content.

  These results are plotted on the graph of FIG. 3 with the Zn content on the horizontal axis and the Ni content on the vertical axis. The left side of the trapezoid is a line of Formula 1, the vertical broken line is a line of 33% by mass of Zn that is distinguished from Examples 2, 4, 5, 7, and 8, and the broken line on the right side is a line of Formula 3. The solid line on the right side is the line of Equation 2. The upper base is a line with 5.5% by mass of Ni, the lower base is a line with 0.3% by mass of Ni, and the upper horizontal broken line is a line with 4.5% by mass of Ni. From these, it can be seen that Examples 11 to 25, all of which were evaluated as ◯, are located in a central region surrounded by a broken line, and Examples 1 to 10 having evaluations of Δ in part. Is located in the area surrounded by the solid line outside. Moreover, the comparative examples 1-3 which do not contain Ni are evaluated as x regardless of the inequality line.

  Regarding Zn and Ni, combinations in which one content is almost the same and the other content is varied are shown in Table 2. Comparative Example 1 and Example 2 are combinations in which Zn is arranged around 33% by mass and the presence or absence of Ni is changed. In Example 2, it can be seen that the tensile strength is greatly improved by the addition of Ni. Comparative Example 3 and Example 12 are combinations in which Zn is aligned around 37 mass% and the presence or absence of Ni is changed. In Comparative Example 3, it is shown that dezincification corrosion occurs when Zn increases, but in Example 12 where Ni is added, it is shown that it is completely suppressed. Comparative Example 6 and Examples 3, 20, and 24 are combinations in which the amount of Ni is changed by aligning at about 39% by mass with more Zn. When Zn is increased, it can be seen that dezincification corrosion cannot be sufficiently suppressed only by adding a little Ni, and it is necessary to increase the amount of Ni to some extent. In Example 3 that satisfies Equation 2, this is slightly improved, In Examples 20 and 24 that satisfy Equation 3, it is shown that this is further improved. In contrast, Examples 5, 18, 20, 6 and Comparative Example 9 are combinations in which the amount of Zn is changed by aligning Ni around 1.5% by mass. Example 5 shows that when Zn is less than 33% by mass and there is a sufficient amount of Ni, the tensile strength remains somewhat uneasy, and in Examples 18 and 20 where Zn is sufficient, Has been improved. However, in Example 6, which does not satisfy Formula 3 because Zn increases too much, there is a sign of a problem in the maximum depth of dezincification corrosion, and in Comparative Example 9 where Zn increases so as not to satisfy Formula 2, the dezincification depth is maximum. Both averages became a problem. The range in which the physical properties are balanced by the addition of Ni is shown.

<Verification of fluctuations in P-1>
Based on the value of Example 20, Comparative Example 11 and Examples 26 to 30 in which the content of P was increased from 0 were prepared while adjusting the content other than P to a value close to this. Table 3 shows Comparative Example 11 (P = 0) and Examples 26 to 28, 20, and 29 to 30 in which these are arranged in the order of the P content. In Comparative Example 11 in which P was less than the detection limit, dezincification corrosion was severe, but in Examples 26 to 28 in which P was added, dezincification corrosion was improved according to the amount added. On the other hand, the elongation fluctuated in a complicated manner with respect to the change of P, and in Table 3, the maximum was found in Example 20, but when P increased further, the elongation turned to a decrease, and P was 0.450 mass. % Of Example 30 decreased to the extent that the evaluation was Δ.

<Verification of fluctuations in P-2>
On the basis of the value of Example 18, Comparative Examples 12 and 13 were prepared in which the content of P was increased to 0.5% by mass or more while the content other than P was adjusted to a value close to this. These are shown in Table 4 in order of P content. In Comparative Example 12 in which P exceeded 0.5 mass%, both tensile strength and elongation were significantly deteriorated, and in Comparative Example 13 in which P was close to 1.0 mass%, the dezincification corrosion was remarkably deteriorated, and castability was improved. Also caused problems.

<Verification of changes in Bi>
Comparative Examples 14, 15 and Examples in which the Bi content was increased from 0% by mass to 7.68% by mass while adjusting the content other than Bi to a value close to this based on the value of Example 19. 31-34 were prepared. These are shown in Table 5 in the order of Bi content, in the order of Comparative Example 14, Example 31, Example 19, Examples 32 to 34, and Comparative Example 15. In Comparative Example 14 where Bi is less than the detection limit, dezincification corrosion was remarkable, but in Example 31 where Bi was added in an amount of 0.30% by mass, this was remarkably improved. Up to Example 33 where the Bi content was close to 4.0% by mass, the dezincification corrosion resistance tended to improve as Bi increased, but in Example 34 where Bi exceeded 4.0% by mass, The dezincification corrosion property turned worse, and in Comparative Example 15 in which Bi was further increased, not only the dezincification corrosion resistance but also the mechanical properties were remarkably deteriorated.

<Verification of Al content>
Example 35, Example 36, and Comparative Example 16 were prepared by increasing the amount of Al that was less than the detection limit in Example 18 while adjusting the content to a value close to this based on the value of Example 18. Prepared. These are shown in Table 6 in order of the Al content. As the Al content increased, the tensile strength improved significantly. On the other hand, the dezincification corrosion resistance deteriorates as the Al increase increases, and the elongation also decreases. When Al exceeds 1.0 mass%, the dezincification corrosion exceeds the allowable limit.

<Verification of Sn content>
Based on the value of Example 18, while adjusting the content to a value close to this, Example 37 and Comparative Example 17 were prepared in which the amount of Sn that was less than the detection limit in Example 18 was increased. These are shown in Table 7 in order of Sn content. When Sn is contained, the dezincification corrosion resistance is remarkably deteriorated, and in Example 37 of 0.29% by mass, the dezincing depth is already the maximum, the influence of both the average is large, and the average is in the range of ○, The maximum was rated △. In the comparative example 17 of 0.38% by mass, a practically problematic value was obtained. In Comparative Example 17, since the value of dezincification corrosion was remarkably bad, the mechanical properties were not measured.

<Verification of Si content>
Based on the value of Example 18, while adjusting the content to a value close to this, Example 38 and Comparative Example 18 in which the amount of Si that was less than the detection limit in Example 18 was increased were prepared. These are shown in Table 8 in order of Si content. The elongation decreased with the increase of Si, and when it exceeded 0.5 mass%, the evaluation of elongation was x. However, the anti-dezincing corrosion resistance once deteriorated in Example 38 when Si was added, but has turned to improvement in Comparative Example 18 in which more Si is added, and it is difficult to manage the physical properties that change depending on the amount of Si added. It was shown that. For this reason, it is considered that Si should be less than the detection limit.

<Verification of B content>
Based on the value of Example 18, while adjusting the content to a value close to this, Examples 39 to 42 and Comparative Example 19 were prepared in which the amount of B that was less than the detection limit in Example 18 was increased. . These are shown in Table 9 in order of content of B. Up to Example 41, the tensile strength and dezincification resistance improved with the increase of B. However, in Example 42 where B is 0.105% by mass, castability is slightly deteriorated due to an increase in intermetallic compounds due to B, shrinkage cavities, etc., and in dezincification corrosion, B is somewhat less than the detection limit. Declined. Further, in Comparative Example 19 in which B is 0.201% by mass, the machinability is remarkably lowered by the intermetallic compound, and a large amount of shrinkage nest is generated, so that the castability deteriorates to a state where it is difficult to apply as a brass member product for water supply. Furthermore, the maximum dezincification corrosion depth was deteriorated by 2.5 times or more compared with Example 18.

<About measured data of dezincing depth>
The photograph selected about the characteristic example among the observation data of the depth of a dezincification corrosion in said dezincification corrosion test is shown.

  FIG. 4 shows a cross-sectional enlarged photograph of 100 times that of the sample of Comparative Example 9 in which zinc is 41.2% by mass and does not satisfy Formulas 2 and 3. As a result of the measurement, the maximum dezincification corrosion depth was 313.3 μm, and the dezincification corrosion average depth was 253.4 μm, and x. Although it is difficult to confirm in black and white, the part discolored from the vicinity of the surface causes dezincing corrosion as a whole.

  FIG. 5 shows a 200-fold enlarged photograph of the sample of Example 22 in which the overall evaluation is ○. It is a double scale of FIG. As a result of the measurement, the maximum dezincification corrosion depth was 122.3 μm, and the average dezincification corrosion depth was 41.1 μm. As can be seen from black and white, the vicinity of the surface is not discolored and it can be seen that there is almost no phase change.

  FIG. 6 shows a 200-times enlarged photograph of the sample of Comparative Example 11 that does not contain P. It is the same scale as FIG. As a result of measurement, as a result of measurement, the maximum dezincification corrosion depth was 293.9 μm, and the average dezincification corrosion depth was 206.5 μm. Although it is difficult to confirm in black and white, there is a part where the part that has undergone a color change and phase change has penetrated deeply into the inside, and this part has caused dezincing corrosion greatly.

  FIG. 7 shows a 200-times enlarged photograph of the cross section of the sample of Comparative Example 14 that does not contain Bi. It is the same scale as FIG. As a result of the measurement, the maximum dezincification corrosion depth was 442.6 μm, and the average dezincification corrosion depth was 334.8 μm. Although it is difficult to confirm with black and white, the part where the phase change has occurred due to discoloration has reached a depth of around 200 μm, and the maximum depth of dezincification corrosion has reached even deeper than the discoloration range. It was.

Claims (3)

Ni is contained in an amount of 0.3 to 5.5% by mass, P is contained in an amount of 0.005 to 0.5% by mass, Bi is contained in an amount of 0.1 to 5.0% by mass, and Zn is contained. Contains,
The content (mass%) of Zn and Ni satisfies the following formulas (1) and (2),
Brass alloy for water supply components with the balance being copper and trace elements.
Zn + 2.2 × Ni ≧ 32.5 (1)
Zn-1.3 × Ni ≦ 38.6 (2)   The brass alloy for water supply members which further contained 0.001 mass% or more and 0.15 mass% or less B in the brass alloy for water supply members concerning Claim 1.   The brass alloy for water supply members which contains 0.2 mass% or more and 1.0 mass% or less of Al further to the brass alloy for water supply members concerning Claim 1 or Claim 2.

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