JP2723817B2 - Bronze casting alloy for materials of drinking water equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alloy relating to a copper alloy casting containing lead as one element in a copper alloy component, and more particularly to an alloy used for equipment, materials, valves, fittings, meters, etc. for facilities related to drinking water, and in general. Related to alloys applied to industrial equipment materials.

[0002]

2. Description of the Related Art A bronze casting conventionally used as a drinking water device (equivalent to a JIS BC or LBC system)
Since is excellent in castability, workability, and pressure resistance, it is widely used in industrial products.

[0003] Bronze casting alloys have a wide solidification temperature range of about 100 ° C due to the characteristics of the contained metal, so that microporous (microbubbles) are generated throughout the casting during solidification. Since it does not become an alloy with a metal, it escapes from the shell of the porous nucleus and is filled with grain boundaries and microbubbles to play a role in maintaining the pressure resistance of the alloy.

[0004] However, lead is a harmful metal component to the human body, and it is considered that elution of lead into water should be minimized.

[0005] In terms of environmental protection, the Ministry of Health and Welfare has determined that the standard for elution of lead in which water dissolves in water is 0.1 ppm or less as an environmental standard for drinking water.
m, which was strictly revised to 1/2 of that before. However, the current state of the current JIS bronze casting alloy does not meet the standard value even in flowing water.

[0006]

The problem to be solved by the present invention is to maintain the above-mentioned reference value of 0.05 ppm while maintaining the current JIS standard chemical composition, mechanical properties and pressure resistance.
An object of the present invention is to provide a bronze casting alloy capable of holding the following.

[0007]

According to the present invention, there is provided a base metal which retains the functionality (castability, mechanical properties, workability, pressure resistance) while preventing the elution of lead in the metal to 0.05 ppm or less. Japanese Industrial Standard-JIS that contains considerable lead to have
-H5111 BC1 and BC1 whose lead content is adjusted or BC6 alloy base added with titanium, boron and magnesium as an improving element to combine the base metal and the added element Is a modification of

[0008]

[Function] When titanium is added to the alloy base of BC1 or BC6 of Japanese Industrial Standards-JIS-H5111, the crystal nucleus of the entire copper alloy is rapidly refined, and lead with a low melting temperature is confined in the crystal nucleus. To prevent lead out of the shell.

On the other hand, since the addition of titanium lowers the strength of the crystal grain boundary, boron that forms an interstitial intermetallic compound is added to compensate for this, and the boron is deflected to the grain boundary to reinforce the grain boundary, and , Due to boron's unique crystal refining effect,
Prevents the crystal from growing again during solidification of the copper alloy.

Furthermore, the elution of lead is drastically reduced by chemically stabilizing lead by adding magnesium.
Note that the addition of only titanium or boron alone has the effect of rapidly miniaturizing the crystal nuclei of the entire copper alloy, so that the elution of lead can be prevented to some extent.

[0011]

[Example] The composition ratio of BC1 alloy in Japanese Industrial Standards-JIS-H5111 is copper 79.0% -83.0%, tin 2.0% -4.0%, zinc
It is 8.0% to 12.0%, lead is 3.0% to 7.0%, and 0.5% to 1.0% nickel and less than 0.1% iron are planned as impurities.

In the Japanese Industrial Standard JIS-H5111, the component ratio of BC6 alloy is 83% -87.0% copper, 4.0% -6.0% tin, 4.0% -6.0% zinc, and 4.0% -6.0% lead. In addition, 0.1% to 1.0% nickel and less than 0.1% iron are planned as impurities.

[0013] As described above, the present invention uses BC1 and BC6 with good leadability and good castability and workability as a material for equipment for drinking water among the bronze castings of JIS-H5111 based on titanium alloy. , Boron, and magnesium are added and processed in the form of ingots, intermediate alloys, and fluxes in a molten alloy processing furnace, and then cast into a mold, such as a sand mold, a shell mold, or a mold, or a vanishing model casting to produce a bronze alloy casting. is there.

Therefore, BC1 and BC6 of JIS-H5111
JIS-H5111 has a high content of lead in JIS-H5111, it is considered to be suitable as a material for equipment for drinking water because of its excellent castability and processability. For BC1, the lead content was kept to a minimum) and the base metal ingot was 2
Each type of ingot is manufactured with a certain amount of titanium, boron, and magnesium added to it in a stepwise manner. For each ingot and sample, tensile strength, elongation, hardness, castability, workability, lead dissolution, pressure resistance The test of sex etc. was performed.

The base metal ingots are No. 1 and No. 2
Made a kind. For the chemical composition of each ingot,
The No. 1 ingot is shown in Tables 1 to 3, and the No. 2 ingot is shown in each upper row in Tables 7 to 11, with the balance being copper and unavoidable impurities.

Here, No. 2 ingot is JIS-H5111 B
On the other hand, the No. 1 ingot corresponds to BC1 except that the lead component ratio is reduced to the BC7 level.

In each ingot, nickel has a regulating or catalytic function in producing an alloy. On the other hand, iron is a negative factor in the present invention among the inevitable impurities.

It has been found that a large amount of iron combines with the added titanium and boron to form an alloy having high hardness, and particularly deteriorates workability. Therefore, the content of iron is desirably 0.1% or less.

Next, a fixed amount of titanium, boron and magnesium were added to each ingot alone or in combination to prepare a copper alloy sample. In addition, two samples of the same component were produced because each test was performed twice for the same product.

Table 1 shows the components of the sample obtained by adding only a certain amount of titanium to the No. 1 ingot, Table 2 shows the components of the sample obtained by adding a certain amount of boron thereto, and Table 3 shows the components of the sample obtained by adding a certain amount of boron to the No. 1 ingot. 2 shows the components of a sample to which amounts of titanium, boron and magnesium were added, respectively.

[Table 1]

[Table 2]

[Table 3]

Table 4 shows the components of the sample obtained by adding only a certain amount of titanium to the No. 2 ingot, Table 5 shows the components of the sample obtained by adding a certain amount of boron thereto, and Table 6 shows the components of the sample obtained by adding a certain amount of boron to the No. 2 ingot. 2 shows the components of a sample to which amounts of titanium, boron and magnesium were added, respectively.

[Table 4]

[Table 5]

[Table 6]

The amount and role of the elements added to each ingot will be described below.

Titanium was added in the range of 0.01% to 0.05%. By adding titanium in the above range, the crystal of the entire copper alloy is rapidly refined as a substitutional intermetallic compound (the crystal size is reduced to 1/2 to 1/5).
As a result, the crystal nucleus of the copper alloy having a high solidification temperature is refined, so that the solidification of the crystal shell is accelerated, and the lead has a function of drastically reducing the outflow of lead from the shell.

Boron was added in the range of 0.02% to 0.1%. The miniaturization with titanium is performed rapidly as described above, but at that time, the mechanical strength is lowered because the grain boundary strength is weakened. Therefore, boron, which is a metal that forms an interstitial intermetallic compound, is added for the purpose of supplementing it.

As a result, boron is deflected to the grain boundaries and reinforces the grain boundaries. Although slower than titanium, boron also has the function of making the crystal finer. Therefore, since the solidification temperature range of bronze is as wide as about 100 ° C., crystals tend to re-grow during solidification, but boron has a role to prevent it.

[0026] Magnesium was added in the range of 0.5% to 1%. Magnesium was added to the third composition as an element having the effect of stabilizing lead.

Each of the copper alloys in the above tables was tested and observed for tensile tests, hardness, castability, workability, lead dissolution, and pressure resistance. The test and observation criteria are as follows. 1. Prior to each test, deacidification with P: 0.03% was performed. 2. Tensile test and measured value of hardness are JIS-Z2241 and JIS
According to S-Z2243. 3. The castability and workability were compared and observed with BC6 (PB5%), and 1 to 5 points (5 points were the best) were evaluated. 4. The lead elution test was performed under the condition that the test piece was immersed in the same tap water at 15 ° C. for 50 hours. 5. With respect to the pressure resistance test, for each sample, two types, a fresh sand casting (product A) and a disappearing model casting (product B) were manufactured. 6. The pressure resistance test was carried out by using a sample cast as a water meter (minimum wall thickness: 3 m / m) by casting a mold and a vanishing model with each sample alloy.

As a result, the data shown in Tables 7 to 12 were obtained. At a certain distribution value shown in Tables 9 and 12, the elution of lead was suppressed to half or less of the conventional value, and the pressure resistance, strength and It was confirmed that the mechanical properties were improved.

Hereinafter, the results shown in each table will be described.

Table 7 shows data when only titanium (Ti) was added to the No. 1 ingot.

[Table 7] The effect of crystal refinement was that titanium addition was 0.01 to 0.05
%, Which is about 1/3 to 1/4 of the diameter compared to the NO.1 ingot without titanium added. The elution of lead was slightly improved from No. 1 ingot for samples 1 to 6,
In all cases, the standard value of 0.05 ppm could not be cleared. Materials 5 and 6 with a large amount of added titanium have poor hot water flow,
As such, it was unsuitable for thin casting.

Table 8 shows data when titanium (Ti) and boron (B) were added to No. 1 ingot.

[Table 8] The crystal refining effect is almost the same as that of the case where only titanium is added, and it is spheroidized and the grain boundary strength is increased as compared with the case where only titanium is added, so that the variation in hydraulic strength is small. Was. In addition, although the elution amount of lead decreased as a whole as compared with the case where only titanium was added, it still did not clear the standard value of 0.05 ppm.

With respect to pressure resistance and mechanical properties, the vanishing casting, which can be poured in a reducing atmosphere, was superior to the case of the sand mold cavity mold. Samples 5 and 6 had poor molten metal flow, were unsuitable for thin casting, and leaked due to a molten metal phenomenon.

Table 9 shows data when titanium (Ti), boron (B) and magnesium (Mg) were added to No. 1 ingot.

[Table 9] The mechanical properties, castability, workability, and microstructure of the microstructure were almost the same as those obtained when Ti and B were added to the No. 1 ingot, but the elution of lead was very effective. In 4 and 6, the standard value of 0.05 ppm was cleared. Overall, the vanishing model castings were more stable.

Table 10 shows data when only titanium (Ti) was added to No. 2 ingot.

[Table 10] The crystal refining effect is remarkable, and the crystal is 1/3 to 1/4 in diameter.
Rank. In the structure, there was not much lead outflow at the grain boundaries, but the lead elution was more than in the case of No. 1 ingot (Table 7),
None of them cleared the standard value of 0.05 ppm. In addition,
Samples 5 and 6 containing a large amount of Ti had poor castability.

Table 11 shows data when titanium (Ti) and boron (B) were added to No. 2 ingot.

[Table 11] As in the case where only titanium was added, there was not much outflow of lead at the grain boundaries, but the difference was that the refined crystals were rounded. As a result, the elution of lead tends to be smaller than in the case where only titanium is added, but the standard value has not yet been cleared.

Table 12 shows that No. 2 ingot had titanium (Ti),
It is data when boron (B) and magnesium (Mg) are added.

[Table 12] The metal crystal structure and mechanical properties were almost the same as No. 2 ingot. The amount of lead eluted in tap water has the effect of remarkably decreasing, and in samples 1-4, the standard value of 0.05 ppm
Cleared.

[0037]

Since the present invention is constructed as described above, the lead in the metal can be maintained while maintaining the functionality (castability, mechanical properties, workability, pressure resistance) of the base metal containing considerable lead. Can be prevented from dissolving into water at 0.05 ppm or less.
Such an effect can be obtained.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-8-120369 (JP, A) JP-A-6-184669 (JP, A) JP-B-53-44136 (JP, B2)

Claims (2)

(57) [Claims] [1] Japanese Industrial Standard JIS-H5111BC1, BC1
For which the lead content was adjusted, or BC
The alloy base of No. 6 contains about 0.01% to 0.1% of titanium or about 0.02% to 0.1% of boron, or both, to form an intermetallic compound and lead component eluted at the grain boundary of the crystal. Bronze casting alloy for drinking water equipment, which replaces lead and intermetallic compounds to prevent the elution of lead components into water 2. The bronze casting alloy according to claim 1, wherein magnesium is added in an amount of about 0.5% -1%.