JP2000119774A - Free cutting copper alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a free cutting copper alloy capable of securing industrially satisfactory machinability while greatly reducing lead content as compared with the conventional free cutting copper alloy. SOLUTION: This free cutting copper alloy has an alloy composition consisting of, by weight, 69-79% copper, 2.0-4.0% silicon, 0.02-0.4% lead, and the balance zinc. It is desirable that one or more elements selected from, by weight, 0.3-3.5% tin, 0.02-0.25% phosphorus, 0.02-0.15% antimony, and 0.02-0.15% arsenic are further incorporated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a free-cutting copper alloy containing almost no lead component.

[0002]

2. Description of the Related Art As a copper alloy having excellent machinability, generally,
Bronze alloys such as JIS H5111 BC6 and JIS
Brass alloys such as H3250-C3604 and C3771 are known. These materials have improved machinability by containing about 1.0 to 6.0% by weight of lead, and have conventionally been used for various products requiring cutting (for example, water for water supply pipes). Plugs, plumbing fittings, valves, etc.)
It is useful as a component material.

[0003] By the way, lead does not form a solid solution in the matrix,
It is intended to improve the machinability by dispersing in the form of particles. However, when the lead content is less than 1% by weight, the chips are spirally connected as shown in FIG. 1 (D). Various troubles such as generation and entanglement with the byte occur.
On the other hand, if the lead content is 1.0% by weight or more, the cutting resistance can be sufficiently reduced, but the lead content is not less than 2.
If the amount is less than 0% by weight, the cut surface becomes rough. Therefore, in order to ensure industrially satisfactory machinability, the lead content is usually set to 2.0% by weight or more. Generally, about 3.0% by weight or more of lead is contained in a wrought copper alloy which requires a high degree of cutting, and about 5% by weight of lead is contained in a bronze-based casting. For example, the above-mentioned JIS H5111 BC6
Has a lead content of about 5.0% by weight.

[0004]

However, since lead is a harmful substance that has an adverse effect on the human body and the environment, its use has recently tended to be greatly restricted. For example, metal vapor generated during high-temperature work such as melting and casting of alloys may contain lead components, or lead components may be eluted from faucet fittings or valves due to contact with drinking water or the like. Yes, there are problems with human health and environmental health. Therefore, recently, developed countries such as the United States have tended to significantly limit the lead content in copper alloys, and in Japan, there has been a strong demand for the development of free-cutting copper alloys with the lowest possible lead content. Have been.

The present invention has been made in response to such global trends and demands, and has been industrially fully satisfied while significantly reducing the lead content as compared with conventional free-cutting copper alloys. It is an object of the present invention to provide a free-cutting copper alloy capable of securing a possible machinability.

[0006]

SUMMARY OF THE INVENTION The present invention proposes the following free-cutting copper alloy to achieve the above object.

That is, in the first invention, 69-79% by weight of copper and 2.0% of silicon are used as a copper alloy having excellent machinability.
The present invention proposes a free-cutting copper alloy (hereinafter, referred to as "first invention alloy") containing -4.0% by weight and 0.02 to 0.4% by weight of lead, and having an alloy composition of zinc. .

[0008] Lead does not form a solid solution in the matrix, but is dispersed in a granular form to improve machinability. On the other hand, silicon contains a γ phase (or κ
By improving the phase, the machinability is improved. As described above, the two have completely different functions in alloy characteristics, but they are common in improving machinability. Focusing on this point, the first invention alloy enables significant reduction of the lead content by adding silicon while securing industrially satisfactory machinability.
That is, the first invention alloy has improved machinability by forming a γ phase by adding silicon.

[0009] When the amount of silicon is less than 2.0% by weight, γ sufficient to ensure industrially satisfactory machinability is required.
No phase formation takes place. Further, the machinability is improved as the amount of silicon added increases, but even if added over 4.0% by weight, there is no machinability improvement effect commensurate with the added amount. By the way, since silicon has a high melting point and a low specific gravity and is easily oxidized, when silicon alone is charged into a furnace during melting of the alloy, the silicon floats on the molten metal surface and is oxidized at the time of melting to form silicon oxide or silicon oxide. And it becomes difficult to produce a silicon-containing copper alloy. Therefore, in the production of an ingot of a silicon-containing copper alloy, the addition of silicon is usually performed after a Cu-Si alloy is added, which increases the production cost. Even in consideration of such alloy production costs, it is not preferable to add silicon in an amount exceeding the amount (4.0% by weight) at which the machinability improving effect is saturated. Further, according to the experiment, the silicon content was 2.0 to
When 4.0 wt% is added, in order to maintain the original characteristics of the Cu—Zn alloy, the copper content is set in a range of 69 to 79 wt% in consideration of the relationship with the zinc content. Has been found to be preferable. For these reasons, in the first invention alloy, the contents of copper and silicon are set to 69 to 79% by weight and 2.0 to 4.0% by weight, respectively. The addition of silicon improves machinability,
The flowability, strength, wear resistance, stress corrosion cracking resistance and high temperature oxidation resistance during casting are also improved. Also, ductility and dezincification corrosion resistance are improved to some extent.

On the other hand, the amount of lead added is 0.0
It was set to 2 to 0.4% by weight. That is, in the first invention alloy, the addition of silicon having the above-described functions ensures the machinability even when the amount of lead is reduced, but in particular, the machinability is superior to the conventional free-machining copper alloy. In order to obtain machinability, it is necessary to add 0.02% by weight or more of lead. However, when the amount of lead exceeds 0.4% by weight, the cut surface is rather rough, the workability in hot working (for example, forgeability) is deteriorated, and the ductility in cold is also reduced. If the amount of lead added is as small as 0.4% by weight or less, no matter how strict the lead content regulation that will be enacted in advanced countries including Japan in the near future, it will be It is thought that regulations can be cleared sufficiently. In addition, also in the second to eleventh invention alloys described later, the amount of lead added is set to 0.02 to 0.4% by weight for the above-described reason.

In the second invention, the copper alloy also having excellent machinability includes 69 to 79% by weight of copper, 2.0 to 4.0% by weight of silicon, and 0.02 to 0.4% of lead. weight%
And bismuth 0.02 to 0.4% by weight, tellurium 0.02
-0.4% by weight and one element selected from 0.02 to 0.4% by weight of selenium, and the balance is zinc. Inventive alloy ").

That is, the second invention alloy is composed of the first invention alloy containing 0.02 to 0.4% by weight of bismuth and 0.02 to 2.0% of tellurium.
The alloy composition further contains 0.4% by weight and one of 0.02 to 0.4% by weight of selenium.

Bismuth, tellurium, or selenium, like lead, does not form a solid solution in the matrix, but exhibits a function of improving machinability by dispersing in the form of particles. Is to supplement. Therefore, when any of these is co-added with silicon and lead, the machinability can be further improved beyond the machinability improvement limit by the addition of silicon and lead. In the second invention alloy, noting this point, one of bismuth, tellurium, and selenium is added to further improve the machinability of the first invention alloy. In particular, by adding bismuth, tellurium, or selenium in addition to silicon and lead, a high degree of machinability is exhibited even when a complicated shape is cut at a high speed. However, the effect of improving the machinability due to the addition of bismuth, tellurium or selenium is not exhibited when the amount of each addition is less than 0.02% by weight. On the other hand, since these are more expensive than copper, even if they are added in excess of 0.4% by weight, the machinability is improved with a slight increase in the added amount, but economically. No effect commensurate with the amount added was observed. If the amount exceeds 0.4% by weight, hot workability (for example, forgeability) deteriorates, and cold workability (ductility) also decreases. Moreover, even if heavy metals such as bismuth may have the same problem as lead, it is considered that there is no possibility that a special problem will occur if a small amount of 0.4% by weight or less is added. From these points,
In the second invention alloy, the addition amount of bismuth, tellurium, or selenium was 0.02 to 0.4% by weight. When lead and bismuth, tellurium or selenium are co-added, it is preferable that the total addition amount of both is set to 0.4% by weight or less. When the total amount of addition exceeds slightly 0.4% by weight, the workability in hot and the ductility in cold decrease, though not as much as when the amount of single addition exceeds 0.4% by weight. This is because there is a risk that the cutting may start or the chip form may shift from FIG. 1 (B) to FIG. 1 (A). by the way,
Since bismuth, tellurium, or selenium improves machinability by a function different from that of silicon as described above, the proper contents of copper and silicon are not affected by their addition. Therefore, the contents of copper and silicon in the second invention alloy were the same as those in the first invention alloy.

Further, in the third invention, as a copper alloy also having excellent machinability, 70 to 80% by weight of copper, 1.8 to 3.5% by weight of silicon, and 0.02 to 0.4% of lead. weight%
0.3 to 3.5% by weight of tin and 1.0 to 1.0% of aluminum
A free-cutting copper alloy containing 3.5% by weight and at least one element selected from 0.02 to 0.25% by weight of phosphorus and having an alloy composition consisting of zinc in the remainder (hereinafter referred to as “third alloy”). Inventive alloy ").

When tin is added to a Cu—Zn alloy,
Like silicon, it forms a γ phase to improve machinability. For example, by adding 1.8 to 4.0% by weight of tin to a Cu-Zn-based alloy containing 58 to 70% by weight of Cu, even if silicon is not added, good machinability is obtained. Show. Therefore, by adding tin to the Cu—Si—Zn-based alloy, the formation of the γ phase can be promoted, and the machinability of the Cu—Si—Zn-based alloy can be further improved. The formation of the gamma phase by tin is 1.0
When the amount reaches 3.5% by weight, a saturated state is reached. If the amount of tin exceeds 3.5% by weight, not only the effect of forming the γ phase becomes saturated, but also the ductility decreases. Also, the amount of tin added was 1.0% by weight.
When the amount is less than 0.5, the effect of forming the γ phase is small, but the amount of addition is 0.1.
When the content is 3% by weight or more, there is an effect of dispersing and homogenizing the γ phase formed by silicon, and the machinability is also improved by the dispersion effect of the γ phase. That is, if the amount of tin added is 0.3% by weight or more, the machinability is improved by the addition.

Also, aluminum has a function of promoting the formation of the γ phase, similarly to tin, and aluminum is added together with or instead of tin to form Cu—Si—Z
The machinability of the n-based alloy can be further improved. Aluminum has a function to improve the strength, abrasion resistance, resistance to high-temperature oxidation, and a function to lower the alloy specific gravity, in addition to the machinability. It is necessary to add 1.0% by weight. However, 3.
Even if it is added in excess of 5% by weight, the machinability improving effect commensurate with the added amount is not observed, and the ductility is reduced as in the case of tin.

Phosphorus does not have the function of forming a γ phase unlike tin and aluminum. However, the γ phase generated by adding silicon or by co-adding one or both of tin and aluminum with the phosphorus is uniform. And the function of improving the γ-phase distribution is provided. With such a function, the machinability by the γ-phase formation can be further improved. Also,
By the addition of phosphorus, the crystal grains of the α phase in the matrix are refined at the same time as the dispersion of the γ phase, thereby improving the hot workability and improving the strength and the stress corrosion cracking resistance. Further, there is also an effect of remarkably improving the flowability of the molten metal during casting. Such an effect by the addition of phosphorus is not exhibited when the addition is less than 0.02% by weight. On the other hand, if the added amount of phosphorus exceeds 0.25% by weight, the effect of improving machinability or the like corresponding to the added amount cannot be obtained, and excessive addition leads to deterioration of hot forgeability and extrudability.

In the third invention alloy, paying attention to this point,
In a Cu-Si-Pb-Zn-based alloy (first invention alloy), 0.3-3.5% by weight of tin, 1.0-3.5% by weight of aluminum, and 0.02-0.25% by weight of phosphorus are added. By adding at least one of them, the machinability is further improved.

By the way, tin, aluminum or phosphorus improves the machinability by the function of forming the γ phase or the function of dispersing the γ phase as described above. Has a close relationship with Therefore, in the third invention alloy in which tin, aluminum or phosphorus is added to silicon, the function of improving the machinability by replacing the first invention alloy with silicon is exhibited, and the machinability is improved irrespective of the γ phase. The required addition amount of silicon is smaller than that of the second invention alloy to which bismuth, tellurium, or selenium is added, which exhibits a function of improving (a function of improving machinability by dispersing in a matrix form in a granular form). . That is, even if the silicon addition amount is less than 2.0% by weight, and if it is 1.8% by weight or more, it is possible to obtain industrially satisfactory machinability by co-adding tin, aluminum or phosphorus. it can. But,
Even if the amount of silicon is 4.0% by weight or less, if it exceeds 3.5% by weight, the effect of improving machinability by adding silicon becomes saturated by co-adding tin, aluminum or phosphorus. . From this point, in the third invention alloy, the addition amount of silicon is set to 1.8 to 3.5% by weight. Further, from the relation with the addition amount of silicon and the relation with addition of tin, aluminum or phosphorus, the upper and lower limits of the copper content are slightly larger than those of the second invention alloy, and the preferable content is 70 to 70%. 80
% By weight.

Further, in the fourth invention, as a copper alloy also having excellent machinability, 70 to 80% by weight of copper, 1.8 to 3.5% by weight of silicon, and 0.02 to 0.4% of lead. weight%
0.3 to 3.5% by weight of tin and 1.0 to 1.0% of aluminum
One or more elements selected from 3.5% by weight and phosphorus 0.02 to 0.25% by weight, bismuth 0.02 to 0.4% by weight, tellurium 0.02 to 0.4% by weight and selenium 0.0
A free-cutting copper alloy (hereinafter, referred to as a "fourth invention alloy") containing one element selected from 2 to 0.4% by weight and having an alloy composition with the balance being zinc is proposed.

That is, in the fourth invention alloy, bismuth 0.02 to 0.4% by weight and tellurium 0.02 to
The alloy composition further contains 0.4% by weight or any of 0.02 to 0.4% by weight of selenium. The reason for adding these elements and the reason for determining the amount of addition are described for the second invention alloy. It is the same as

Further, in the fifth invention, the copper alloy having excellent corrosion resistance in addition to machinability is provided in an amount of 69 to 79% by weight of copper.
2.0 to 4.0% by weight of silicon and 0.02 to 0.4% of lead.
Wt%, tin 0.3-3.5 wt%, phosphorous 0.02-0.
25% by weight, 0.02 to 0.15% by weight of antimony and 0.02 to 0.15% by weight of arsenic and at least one element selected from the group consisting of zinc. A machinable copper alloy (hereinafter referred to as "fifth invention alloy") is proposed.

That is, the fifth invention alloy is the same as the first invention alloy, except that 0.3 to 3.5% by weight of tin, 0.02 to 0.25% by weight of phosphorus, 0.02 to 0.15% by weight of antimony and 0.
The alloy composition further contains at least one of 02 to 0.15% by weight.

Tin has a function of improving corrosion resistance (anti-zinc corrosion resistance, corrosion resistance) and forgeability in addition to the function of improving machinability. That is, the corrosion resistance of the α-phase matrix can be improved, and the corrosion resistance, forgeability, and stress corrosion cracking resistance can be improved by dispersing the γ phase. In the fifth invention alloy,
Corrosion resistance is improved by such a function of tin, and machinability is improved mainly by the effect of silicon addition. Therefore, the contents of silicon and copper are the same as those of the first invention alloy. On the other hand, in order to exhibit the function of improving corrosion resistance and forgeability, it is necessary that the amount of tin added be at least 0.3% by weight. However, the effect of improving the corrosion resistance and forgeability by adding tin exceeds 3.5% by weight, the effect corresponding to the added amount cannot be obtained, and it is economically useless.

As described above, phosphorus not only has a function of improving machinability but also has a corrosion resistance (dezincification corrosion resistance, It has the function of improving pickling resistance, forgeability, stress corrosion cracking resistance and mechanical strength. In the fifth invention alloy, the function of phosphorus improves corrosion resistance and the like, and the machinability is improved mainly by the effect of silicon addition. The effect of improving the corrosion resistance etc. by adding phosphorus is
This is exhibited by adding a small amount of phosphorus, and is exhibited by adding 0.02% by weight or more. However, 0.25% by weight
If the amount exceeds the above range, not only the effect corresponding to the added amount is not obtained, but also the hot forgeability and the extrudability are rather lowered.

Antimony and arsenic also improve anti-zinc corrosion resistance, etc., in a very small amount (0.02% by weight or more), like phosphorus. However, even if it is added in excess of 0.15% by weight, not only the effect commensurate with the amount added is not obtained, but also the hot forgeability and extrudability are rather reduced, as in the case of excessive addition of phosphorus.

From these facts, in the fifth invention alloy, in addition to the same amounts of copper, silicon and lead as in the first invention alloy,
By adding at least one of tin, phosphorus, antimony, and arsenic as an element for improving corrosion resistance within the above range, not only machinability but also corrosion resistance and the like can be improved. In the fifth invention alloy, tin and phosphorus mainly function as corrosion resistance improving elements similar to antimony and arsenic. As with the inventive alloy, the amounts of copper and silicon were 69-79% by weight and 2.
It is set to 0 to 4.0% by weight.

Further, in the sixth invention, the copper alloy, which is also excellent in machinability and corrosion resistance, comprises 69 to 79% by weight of copper.
2.0 to 4.0% by weight of silicon and 0.02 to 0.4% of lead.
Wt%, tin 0.3-3.5 wt%, phosphorous 0.02-0.
At least one element selected from the group consisting of 25% by weight, 0.02 to 0.15% by weight of antimony and 0.02 to 0.15% by weight of arsenic, 0.02 to 0.4% by weight of bismuth, and 0.1% of tellurium; A free-cutting copper alloy (hereinafter referred to as “No. 1”) containing an element selected from the group consisting of 02 to 0.4% by weight and 0.02 to 0.4% by weight of selenium, and the balance being zinc. 6
Inventive alloy ").

That is, in the sixth invention alloy, bismuth 0.02 to 0.4% by weight and tellurium 0.02 to
It has an alloy composition further containing any one of 0.4% by weight and 0.02 to 0.4% by weight of selenium. Similar to the second invention alloy, bismuth, In addition to improving the machinability by adding any one of tellurium and selenium, tin, phosphorus,
Corrosion resistance and the like are improved by adding at least one selected from antimony and arsenic.
Therefore, the addition amounts of copper, silicon, lead, bismuth, tellurium, and selenium are the same as those of the second invention alloy, and tin,
The addition amounts of phosphorus, antimony and arsenic were the same as those of the fifth invention alloy.

In the seventh invention, the copper alloy having excellent strength and abrasion resistance in addition to machinability includes copper 62 to 7
8% by weight, 2.5 to 4.5% by weight of silicon, and 0.02% of lead
And 0.4% by weight and one or more elements selected from 0.3 to 3.0% by weight of tin, 0.2 to 2.5% by weight of aluminum and 0.02 to 0.25% by weight of phosphorus. , Manganese 0.7
-3.5% by weight and at least one element selected from 0.7-3.5% by weight of nickel, and the balance is zinc. 7 invention alloy ").

Manganese or nickel combines with silicon to form a fine intermetallic compound of Mn _X Si _Y or Ni _X Si _Y and precipitates uniformly on the matrix, thereby improving wear resistance and strength. Therefore, by adding one or both of manganese and nickel, high strength,
The wear resistance is improved. Such effects are exhibited when manganese and nickel are each added in an amount of 0.7% by weight or more. However, even if it is added in excess of 3.5% by weight, the effect becomes saturated, and an effect commensurate with the added amount cannot be obtained. Silicon is added with manganese or nickel, taking into account the amount of consumption required for the formation of an intermetallic compound with manganese or nickel.
It was decided to add 4.5% by weight.

The addition of tin, aluminum and phosphorus strengthens the α phase of the matrix and improves machinability. Tin and phosphorus improve the strength and wear resistance by dispersing the α phase and the γ phase, and also improve the machinability. Tin improves the strength and machinability by adding 0.3% by weight or more,
When added in excess of 3.0% by weight, ductility decreases. Therefore, in the seventh invention alloy in which high strength and wear resistance are improved, the addition amount of tin is set to 0.3 to 3.0% by weight in consideration of the effect of improving machinability. Aluminum is
It contributes to the improvement of abrasion resistance and the matrix strengthening function is 0.1%.
It is exhibited by addition of 2% by weight or more. However, 2.5
If added in excess of weight percent, the ductility decreases. Therefore, considering the machinability improvement effect, the addition amount of aluminum is set to 0.2 to 2.5% by weight. Further, by adding phosphorus, the crystal grains of the α-phase in the matrix are refined at the same time as the dispersion of the γ-phase, thereby improving the hot workability and improving the strength and wear resistance. In addition, there is also an effect of significantly improving the flowability of the molten metal during casting. Such an effect can be achieved by adding phosphorus to 0.1.
This can be achieved by adding in the range of 02 to 0.25% by weight. The amount of copper was set to 62 to 78% by weight based on the relationship with the amount of silicon added and the relationship between manganese and nickel combined with silicon.

Further, in the eighth invention, as a copper alloy excellent in high temperature oxidation resistance in addition to machinability, copper 69 to 79
Wt%, silicon 2.0-4.0 wt%, lead 0.02-0.
A free-cutting copper alloy containing 4% by weight, 0.1-1.5% by weight of aluminum and 0.02-0.25% by weight of phosphorus, and the balance being zinc (hereinafter referred to as "the eighth invention"). Alloy ”).

Aluminum is an element that improves the strength, machinability, and wear resistance, and also improves the high-temperature oxidation resistance. As described above, silicon also has functions of improving machinability, strength, abrasion resistance, stress corrosion cracking resistance, and high temperature oxidation resistance. Improvement of high-temperature oxidation resistance by aluminum is 0.1% by weight by co-addition with silicon.
The above addition is performed. However, aluminum was added to 1.
Even if it is added in excess of 5% by weight, the effect of improving high-temperature oxidation resistance corresponding to the amount added is not observed. From this point, the addition amount of aluminum is set to 0.1 to 1.5% by weight.

[0035] Phosphorus is added to improve the flowability of the molten metal during alloy casting. Phosphorus improves not only the flowability of the molten metal but also the high-temperature oxidation resistance in addition to the above-mentioned machinability and dezincification corrosion resistance. The effect of such phosphorus addition is 0.1.
Exhibited at 02% by weight or more. However, 0.25% by weight
Even if added beyond the above, the effect corresponding to the added amount is not seen,
On the contrary, the alloy becomes brittle. From this point,
The addition amount of phosphorus was 0.02 to 0.25% by weight.

Although silicon is added to improve machinability as described above, silicon also has a function of improving the flowability of molten metal like phosphorus. The improvement of the melt flowability by silicon is exhibited by the addition of 2.0% by weight or more, and overlaps the addition range necessary for improving the machinability.
Therefore, the addition amount of silicon is set to 2.0 to 4.0% by weight in consideration of improvement in machinability.

In the ninth invention, copper alloys having excellent machinability and high-temperature oxidation resistance include copper 69-79.
Wt%, silicon 2.0-4.0 wt%, lead 0.02-
0.4% by weight and 0.1-1.5% by weight of aluminum
0.02 to 0.25% by weight of phosphorus and 0.02 of bismuth
An alloy composition containing at least one element selected from 0.4% by weight, 0.02 to 0.4% by weight of tellurium and 0.02 to 0.4% by weight of selenium, and the balance being zinc. The proposed copper alloy (hereinafter referred to as “ninth invention alloy”) is proposed.

That is, the ninth invention alloy is the same as the eighth invention alloy, except that 0.02 to 0.4% by weight of bismuth and
It is an alloy composition further containing 0.4% by weight and any one of 0.02 to 0.4% by weight of selenium. As described above, bismuth, which is an element for improving machinability similar to lead, is used. By adding the same, the machinability is further improved while ensuring the same high-temperature oxidation resistance as that of the eighth invention alloy.

Further, in the tenth invention, copper alloys having excellent machinability and high-temperature oxidation resistance include copper 69 to 7
9% by weight, 2.0 to 4.0% by weight of silicon, and 0.02% of lead
-0.4% by weight and aluminum 0.1-1.5% by weight
0.02 to 0.25% by weight phosphorus and 0.02 to chromium
A free-cutting copper alloy containing 0.4% by weight and one or more elements selected from 0.02 to 0.4% by weight of titanium and having the balance of zinc (hereinafter referred to as “No. Inventive alloy ").

Chromium and titanium have a function of improving high-temperature oxidation resistance, and the function is remarkably exhibited particularly by a synergistic effect by co-addition with aluminum. Such functions are exhibited at 0.02% by weight or more, regardless of whether they are added alone or co-added,
It is saturated at 0.4% by weight. From such a point, in the tenth invention alloy, chromium 0.0
An alloy composition further containing at least one of 2 to 0.4% by weight and 0.02 to 0.4% by weight of titanium to further improve the high-temperature oxidation resistance of the eighth invention alloy. I have.

In the eleventh invention, the copper alloy having excellent machinability and high-temperature oxidation resistance includes copper 69 to 7
9% by weight, 2.0 to 4.0% by weight of silicon, and 0.02% of lead
-0.4% by weight and aluminum 0.1-1.5% by weight
0.02 to 0.25% by weight phosphorus and 0.02 to chromium
One or more elements selected from 0.4% by weight and 0.02 to 0.4% by weight of titanium;
Wt%, tellurium 0.02 to 0.4 wt% and selenium 0.1 wt%.
The present invention proposes a free-cutting copper alloy (hereinafter, referred to as an "eleventh invention alloy") containing one element selected from 02 to 0.4% by weight and having an alloy composition of zinc.

That is, the eleventh invention alloy is the same as the tenth invention alloy, except that 0.02 to 0.4% by weight of bismuth and 0.0
It has an alloy composition further containing any one of 2 to 0.4% by weight and 0.02 to 0.4% by weight of selenium, and improves the machinability by a function different from that of silicon as described above. By adding bismuth, which is an element similar to lead, etc., the machinability is further improved while securing the high-temperature oxidation resistance similar to that of the tenth invention alloy.

Further, in the twelfth invention, the above-mentioned alloys of the invention are subjected to a heat treatment at 400 to 600 ° C. for 30 minutes to 5 hours, thereby improving the machinability of the alloys. Hereinafter, referred to as a “twelfth invention alloy”).

The alloys of the first to eleventh inventions are added with a machinability improving element such as silicon and have excellent machinability due to the addition of such an element. The machinability may be further improved by heat treatment. For example, when the copper concentration in the first to eleventh invention alloys is high and the γ phase is small and the κ phase is large, the κ phase is changed to the γ phase by the heat treatment, and the γ phase is finely dispersed. Precipitation further improves machinability. In addition, when assuming the production of actual castings, wrought materials, and hot forged products, depending on the conditions of the casting conditions, productivity after hot working (hot extrusion, hot forging, etc.), work environment, etc. May be forcibly air-cooled or water-cooled. In such a case, in the first to eleventh invention alloys, particularly, when the copper concentration is low, the γ phase is slightly less and contains the β phase, but when the heat treatment is performed, the β phase changes to the γ phase. At the same time, the γ phase is finely dispersed and precipitated, and the machinability is improved. However, in any case, if the heat treatment temperature is lower than 400 ° C., the above-mentioned phase change rate becomes slow, and the heat treatment takes an extremely long time, and thus cannot be economically used. Conversely, when the temperature exceeds 600 ° C., the κ phase increases or the β phase appears, so that the effect of improving machinability cannot be obtained. Therefore, considering practicality,
In order to improve machinability, 30 to 400 ° C to 600 ° C
It is preferable to perform the heat treatment for a period of minutes to 5 hours.

[0045]

EXAMPLE As an example, an ingot (having a cylindrical shape having an outer diameter of 100 mm and a length of 150 mm) having the composition shown in Tables 1 to 15 was extruded into a round bar having an outer diameter of 15 mm while hot (750 ° C.). Then, the first invention alloy No. 1001-No. 100
7, the second invention alloy no. 2001-No. 2006, the third invention alloy No. 3001-No. 3010, 4th invention alloy No. 4001-No. 4021, Fifth invention alloy N
o. 5001-No. 5020, the sixth invention alloy No. 6
001-No. 6045, 7th invention alloy No. 7001
-No. 7029, Eighth Invention Alloy No. 8001-N
o. 8008, ninth invention alloy No. 9001-No. 9
006, the tenth invention alloy No. 10001-No. 10
008 and the eleventh invention alloy no. 11001-No. 1
1011 was obtained. Further, an ingot (having a cylindrical shape having an outer diameter of 100 mm and a length of 150 mm) having a composition shown in Table 16 was extruded into a round bar having an outer diameter of 15 mm by hot (750 ° C.). Heat treatment under the conditions shown in
Inventive alloy No. 2 12001-No. 12004 was obtained. That is, No. No. 12001 is the first invention alloy No.
An extruded material having the same composition as No. 1006 was heat-treated at 580 ° C. for 30 minutes. 12002 is N
o. An extruded material having the same composition as that of No. 1006 was heat-treated at 450 ° C. for 2 hours. No. 12003 is the first invention alloy No. The extruded material having the same composition as No. 1007 was No. 1007. No. 12001 was heat-treated under the same conditions (580 ° C., 30 minutes). No. 12004 is No. 100
Extruded material having the same composition as No. 7 It was heat-treated under the same conditions as 12002 (450 ° C., 2 hours).

As a comparative example, an ingot having a composition shown in Table 17 (a cylindrical shape having an outer diameter of 100 mm and a length of 150 mm) was extruded hot (750 ° C.) to obtain an outer diameter of 15 mm.
No. extruded material (hereinafter referred to as “conventional alloy”) No. 13
001-No. 130006 was obtained. In addition, No. 130
01 is equivalent to “JIS C3604”,
No. No. 13002 corresponds to “CDA C36000”. 13003 is "JIS C377
No. 1 ". 13004 is "CD
AC69800 ". Also, N
o. 13005 is equivalent to "JIS C 6191", and is aluminum bronze having the highest strength and abrasion resistance among the copper products specified in JIS. Also, N
o. 13006 is equivalent to "JIS C4622", and is a naval brass having the highest corrosion resistance among the brass products specified in JIS.

[0047]

[Table 1]

[0048]

[Table 2]

[0049]

[Table 3]

[0050]

[Table 4]

[0051]

[Table 5]

[0052]

[Table 6]

[0053]

[Table 7]

[0054]

[Table 8]

[0055]

[Table 9]

[0056]

[Table 10]

[0057]

[Table 11]

[0058]

[Table 12]

[0059]

[Table 13]

[0060]

[Table 14]

[0061]

[Table 15]

[0062]

[Table 16]

[0063]

[Table 17]

Then, in order to confirm the machinability of the first to twelfth invention alloys in comparison with the conventional alloys, the following cutting tests were performed, and the main component force of the cutting, the chip state, and the cutting surface morphology were determined. .

That is, the outer peripheral surface of each extruded material obtained as described above was cut by a lathe with a serious cutting tool (rake angle: -8 °) at a cutting speed of 50 m / min and a cutting depth (cutting allowance). ): 1.5 mm, feed amount: 0.11 mm / re
v. The signal from the three-component dynamometer attached to the cutting tool was converted into a voltage signal by a heavy strain measuring instrument, recorded by a recorder, and converted into a cutting resistance. by the way,
The magnitude of the cutting force is determined by the three-component force, namely, the main component, the feed component and the back component. In this case, the magnitude of the cutting force is determined by the main component (N) showing the largest value among the three components. It was decided to judge. The results were as shown in Tables 18 to 33.

Further, the state of the chips generated by the cutting was observed and classified into four types as shown in FIGS. 1 (A) to 1 (D) according to their shapes, and the results are shown in Tables 1 to 15. By the way, as shown in Fig. (D), when the chip has a spiral shape of three or more turns, processing of the chip (collection and reuse of the chip, etc.)
In addition, it becomes difficult to perform cutting, and troubles such as chip entanglement with the cutting tool and damage to the cutting surface occur, so that good cutting cannot be performed. Further, as shown in Fig. (C), when the chip has a spiral shape of about two turns from an arc shape of about half a roll, a big trouble such as a spiral shape of three or more turns occurs. However, it is still not easy to treat chips, and in the case of performing continuous cutting, there is a possibility that the cutting tool may be entangled or the cutting surface may be damaged. However, when the chip is sheared into a fine needle-shaped piece as shown in (A) or a fan-shaped piece or an arc-shaped piece as shown in (B), the above trouble does not occur, and (C) Since it is not bulky as shown in the figures and (D), the processing of chips is easy. However, if the chips are sheared into a fine shape as shown in FIG. 3A, the chips may sneak into the sliding surface of a machine tool such as a lathe to cause a mechanical obstacle, or to be stuck by fingers or eyes of an operator. May be dangerous. Therefore, in judging the machinability, the one shown in FIG. (B) is the best, the one shown in (A) follows, and the one shown in (C) or (D) is inappropriate. It is appropriate to do. In Tables 18 to 33, those in which the best chip state shown in FIG.
In the figure, a somewhat good chip condition was observed, and "○"
In the graph, (も の) indicates the case where the bad chip state shown in FIG. 7 (C) was observed, and “×” indicates the case where the worst chip state shown in (D) was observed.

After cutting, the quality of the cut surface was judged by the surface roughness. The results are shown in Tables 18 to 33
As shown in FIG. By the way, the maximum height (Rmax) is often used as a standard of the surface roughness, and although it depends on the use of the brass product, it is generally judged that if Rmax <10 μm, the machinability is extremely excellent. 10μ
If m ≦ Rmax <15 μm, it can be determined that industrially satisfactory machinability has been obtained, and Rmax ≧ 15 μm
In the case of m, it can be determined that the machinability is poor. Table 18-
In Table 33, the case where Rmax <10 μm is indicated by “○”.
In the case of 10 μm ≦ Rmax <15 μm, “△” indicates that R
The case where max ≧ 15 μm is indicated by “x”.

As is clear from the results of the cutting tests shown in Tables 18 to 33, the first invention alloy No. 1001-No.
1007, the second invention alloy No. 2001-No. 200
6, the third invention alloy no. 3001-No. 3010, 4th invention alloy No. 4001-No. 4021, Fifth Invention Alloy No. 5001-No. 5020, sixth invention alloy N
o. 6001-No. 6045, 7th invention alloy No. 7
001-No. 7029, Eighth Invention Alloy No. 8001
-No. 8008, ninth invention alloy No. 9001-N
o. 9006, 10th invention alloy No. 10001-N
o. 10008, Eleventh Invention Alloy No. 11001-N
o. No. 11011 and the twelfth invention alloy. 12001-
No. No. 12004 is a conventional alloy No. 1 containing a large amount of lead. No. 13001-No. 13003
It has the same machinability as. In particular, as far as the state of chip formation is concerned, the conventional alloy No. having a lead content of 0.1% by weight or less is used. 13004-No. As compared to the conventional alloy No. 13006, the conventional alloy No. 13001-
No. Excellent machinability compared to 13003.
In addition, the first invention alloy No. 1006 and no. 1007
In comparison with the twelfth invention alloy No. 12
001-No. 12004 has equal or higher machinability, and depending on conditions such as alloy composition, the first
It is understood that the machinability of the eleventh invention alloy can be further improved.

Next, in order to confirm the hot workability and mechanical properties of the first to twelfth invention alloys in comparison with the conventional alloys, the following hot compression test and tensile test were performed.

That is, from each extruded material obtained as described above, the first extruded material having the same shape (outer diameter 15 mm, length 25 mm)
And the 2nd test piece was cut out. Then, in the hot compression test, each first test piece was heated to 700 ° C. and held for 30 minutes, and then compressed at a compression rate of 70% in the axial direction (the height (length) of the first test piece was reduced). It was compressed from 25 mm to 7.5 mm), and the surface morphology (deformability at 700 ° C.) after compression was visually determined. The results were as shown in Tables 18 to 33. Judgment of the deformability was visually performed from the state of cracks on the side surface of the test piece, and in Tables 18 to 33, those in which no cracks occurred were indicated by “○”, and those in which small cracks occurred were indicated by “△”, Those having large cracks are indicated by "x". Further, a tensile test was carried out using each of the second test pieces by a conventional method, and the tensile strength (N /
mm ² ) and elongation (%) were measured.

From the results of the hot compression test and the tensile test shown in Tables 18 to 33, the first to twelfth invention alloys are the same as those of the conventional alloy No. No. 13001-No. 13004 and No. 130
It has a hot workability and a mechanical property equal to or higher than that of 06, and it has been confirmed that it can be industrially suitably used. In particular, regarding the seventh invention alloy, the conventional alloy No. which is the aluminum bronze having the highest strength among the copper-brought products specified in JIS. It has the same mechanical properties as 13005, and is understood to be excellent in high strength.

The first to sixth invention alloys and the eighth to first alloys
2 In order to confirm the corrosion resistance and stress corrosion cracking resistance of the invention alloy in comparison with the conventional alloy, a dezincification corrosion test according to the method specified in "ISO 6509" and "JIS H32"
A stress corrosion cracking test specified in “50” was conducted.

That is, in the dezincification corrosion test of “ISO 6509”, a sample collected from each extruded material was embedded in a phenol resin material such that the surface of the exposed sample was perpendicular to the extrusion direction of the extruded material. The surface of the sample was polished with emery paper to # 1200, and the surface was ultrasonically washed in pure water and dried. The corrosion test sample thus obtained was treated with 1.0% cupric chloride dihydrate (CuCl 2).
Immersed in ₂ · 2H ₂ O) aqueous solution (12.7 g / l), was held for 24 hours at a temperature of 75 ° C., and taken out from the aqueous solution, the maximum value of the dezincification corrosion depth (maximum Dezincification corrosion depth) was measured. The results are shown in Tables 18 and 2.
5 and Tables 28 to 33.

As can be understood from the results of the dezincification corrosion tests shown in Tables 18 to 25 and Tables 28 to 33, the first to fourth invention alloys and the eighth to twelfth invention alloys produced a large amount of lead. Conventional alloy No. No. 13001-No. 5th and 6th invention alloys which have excellent corrosion resistance compared to 13003, and which improve corrosion resistance as well as machinability,
Conventional alloy No., which is a Naval brass with the highest corrosion resistance among the brass products specified in S. It was confirmed that it had extremely excellent corrosion resistance as compared with 130006.

In the stress corrosion cracking test of "JIS H3250", a sample having a length of 150 mm was cut out from each extruded material, and each sample was placed on an arc-shaped jig having a radius of 40 mm. The test piece was bent so that one end thereof was at 45 ° to the other end. Each specimen to which the residual tensile stress was applied in this way was degreased,
After being dried, it was kept in an ammonia atmosphere (25 ° C.) in a desiccator containing 12.5% ammonia water (ammonia diluted with an equal amount of pure water). That is, each test piece is held at a position about 80 mm above the ammonia water level in the desiccator. When the holding time of the test piece in the ammonia atmosphere has passed for 2 hours, 8 hours, and 24 hours, the test piece was taken out of the desiccator, washed with 10% sulfuric acid, and the test piece was cracked. The presence or absence was visually recognized with a magnifying glass (magnification: 10 times). The results were as shown in Tables 18 to 25 and Tables 28 to 33. In these tables, those in which a clear crack was observed when the holding time in the ammonia atmosphere was 2 hours were "XX", and no crack was observed after 2 hours. When a clear crack was observed after 8 hours, it was marked with "X".
No crack was observed after the elapse of time.
A sample in which a clear crack was observed over time was indicated by "△", and a sample in which no crack was observed even after 24 hours was indicated by "○".

As can be understood from the results of the stress corrosion cracking tests shown in Tables 18 to 25 and Tables 28 to 33, the fifth and sixth invention alloys of which the corrosion resistance is improved as well as the machinability are, of course, included. Also, the first to fourth invention alloys and the eighth to twelfth invention alloys, for which corrosion resistance is not particularly taken into consideration, also include the conventional alloy N which is aluminum bronze containing no zinc.
o. It has stress corrosion cracking resistance equivalent to 13005,
Conventional alloy No., which is a Naval brass with the highest corrosion resistance among the brass products specified in S. It was confirmed to have stress corrosion cracking resistance better than 13006.

Further, in order to confirm the high-temperature oxidation resistance of the eighth to eleventh invention alloys in comparison with the conventional alloys, the following oxidation tests were performed.

That is, each extruded material No. 8001-N
o. 8008, no. 9001-No. 9006, N
o. 10001-No. 10008, no. 11001
-No. No. 11011 and No. 13001-13006
From this, a round bar-shaped test piece whose surface was ground to have an outer diameter of 14 mm and cut to a length of 30 mm was obtained, and the weight of each test piece (hereinafter referred to as “weight before oxidation”) was measured. Thereafter, each test piece was stored in a magnetic crucible,
It was left in an electric furnace maintained at 0 ° C. Then, when the standing time has passed 100 hours, the test piece is taken out of the electric furnace, the weight of each test piece (hereinafter referred to as “post-oxidation weight”) is measured, and the oxidation increase is calculated from the pre-oxidation weight and the post-oxidation weight. did. Here, the oxidation increase refers to the surface area 10c of the test piece.
It indicates the degree of weight increase (mg) due to oxidation per m ² , and “weight increase by oxidation (mg / 10 cm ² ) = (weight after oxidation (mg) −weight before oxidation (mg)) × (10 cm ² )
/ Surface area of test piece (cm ² ) ”. That is, the weight after oxidation of each test piece is greater than the weight before oxidation, which is due to high-temperature oxidation. That is, when exposed to a high temperature, oxygen and copper, zinc, and silicon combine to form Cu ₂ O, ZnO, and SiO ₂ , and the weight increases due to the oxygen increment. Therefore,
It can be said that the smaller the degree of the increase in weight (oxidation increase), the more excellent the high-temperature oxidation resistance is, and the results shown in Tables 28 to 31 and 33 are obtained.

As is evident from the results of the oxidation tests shown in Tables 23 to 31 and Table 33, the increase in oxidation of the eighth to eleventh invention alloys is the highest in high-temperature oxidation resistance among the copper products specified in JIS. Conventional alloy N which is aluminum bronze
o. 13005, which is much smaller than other conventional alloys. Therefore, it was confirmed that the eighth to eleventh invention alloys were extremely excellent in high-temperature oxidation resistance in addition to machinability.

[0080]

[Table 18]

[0081]

[Table 19]

[0082]

[Table 20]

[0083]

[Table 21]

[0084]

[Table 22]

[0085]

[Table 23]

[0086]

[Table 24]

[0087]

[Table 25]

[0088]

[Table 26]

[0089]

[Table 27]

[0090]

[Table 28]

[0091]

[Table 29]

[0092]

[Table 30]

[0093]

[Table 31]

[0094]

[Table 32]

[0095]

[Table 33]

As a second embodiment, Tables 9 to 11
Is extruded into a round bar having an outer diameter of 35 mm by hot (700 ° C.) the ingot (in a cylindrical shape having an outer diameter of 100 mm and a length of 200 mm) having the composition shown in FIG. 7001a
-No. 7029a was obtained. In addition, as a second comparative example, an ingot (outer diameter 100 mm, length 2
Extruded into a round bar-shaped extruded material (hereinafter referred to as “conventional alloy”) having an outer diameter of 35 mm. 13001a-No. 13006a
I got In addition, No. 7001a-No. 7029a and No. 13001a-No. 13006a, respectively,
The copper alloy No. described above. 7001-No. 7029 and N
o. No. 13001-No. It has the same alloy composition as 13006.

Then, in the seventh invention alloy no. 7001a-
No. The wear resistance of the conventional alloy no. 130
01a-No. The following abrasion test was performed in order to confirm by comparison with 13006a.

That is, each extruded material obtained as described above was cut into an outer peripheral surface, and then punched and cut to obtain an outer diameter of 32 mm and a thickness (length in the axial direction) of 10 mm. After obtaining a ring-shaped test piece, each test piece was fitted and fixed on a rotatable shaft, and a 50 kg load was applied to a 48 mm-diameter SUS304 roll having an axis parallel to the test piece to make pressure contact. Keep in state. After a while
The SUS304 roll and the test piece rolling thereon are driven to rotate at the same rotation speed (209 rpm) while multi-oil is dropped on the outer peripheral surface of the test piece. When the number of rotations of the test piece reaches 100,000 times, S
The rotation of the US304 roll and the test piece was stopped, and the weight difference before and after the rotation of each test piece, that is, the wear loss (mg)
Was measured. The smaller the loss on wear, the better the copper alloy with excellent wear resistance. The results are shown in Table 34.
~ As shown in Table 36.

As is clear from the results of the wear tests shown in Tables 34 and 36, the seventh invention alloy No. 7001a-N
o. 7029a is a conventional alloy No. No. 13001-No.
13004 and No. Of course, compared to 13006, JI
Conventional bronze alloy No. S, which is an aluminum bronze having the highest wear resistance among the copper products specified in S.S. It was confirmed that the abrasion resistance was superior to that of 13005. Therefore,
When judged comprehensively in consideration of the results of the tensile test described above, the seventh invention alloy has the most excellent abrasion resistance among the brass products specified in JIS in addition to the machinability. It can be said that it has the same high strength and wear resistance as bronze.

[0100]

[Table 34]

[0101]

[Table 35]

[0102]

[Table 36]

[0103]

As will be easily understood from the above description, the first to twelfth invention alloys have a very small amount of lead (0.02 to 0.4 weight%) which is a machinability improving element. %), It is extremely machinable and can be used safely as a substitute for conventional free-cutting copper alloys containing large amounts of lead. There is no environmental health problem at all, and it is possible to sufficiently respond to recent trends in which lead-containing products are being regulated.

Further, the fifth and sixth invention alloys are excellent in corrosion resistance in addition to machinability, and are used for cutting products, forgings, castings, etc. requiring corrosion resistance (for example, water taps). , Water supply and drain fittings, valves, stems, hot water supply piping parts, shafts, heat exchanger parts, etc.), and their practical value is extremely large.

Further, the alloy of the seventh invention is excellent in high strength and wear resistance in addition to machinability, and is a cut product, a forged product or a cast product requiring high strength and wear resistance. It can be suitably used as a constituent material of products and the like (for example, bearings, bolts, nuts, bushes, gears, sewing machine parts, hydraulic parts, etc.), and its practical value is extremely large.

Further, the eighth to eleventh invention alloys are excellent in high-temperature oxidation resistance in addition to machinability, and are used in cutting products, forgings, castings, etc. which require high-temperature oxidation resistance. For example, it can be suitably used as a constituent material of a nozzle for an oil / gas hot air heater, a burner head, a gas nozzle for a water heater, etc., and its practical value is extremely large.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a form of a chip.

Claims (8)

[Claims] 1. Copper 69-79% by weight, silicon 2.0-4.
A free-cutting copper alloy containing 0% by weight and 0.02 to 0.4% by weight of lead, and a balance of zinc. 2. Tin 0.3 to 3.5% by weight, phosphorus 0.02 to
0.25% by weight, 0.02-0.15% by weight of antimony
2. The composition according to claim 1, further comprising at least one element selected from the group consisting of arsenic and 0.02 to 0.15% by weight.
Free-cutting copper alloys described in 1. 3. The method according to claim 1, wherein 70 to 80% by weight of copper and 1.8% to silicon
3.5% by weight, lead 0.02 to 0.4% by weight and tin 0.
3 to 3.5% by weight, aluminum 1.0 to 3.5% by weight
A free-cutting copper alloy containing an alloy composition containing at least one element selected from the group consisting of phosphorus and 0.02 to 0.25% by weight of phosphorus, with the balance being zinc. 4. 62 to 78% by weight of copper and 2.5 to 2.5% of silicon
4.5% by weight, 0.02 to 0.4% by weight of lead, and 0.1% of tin.
3-3.0 wt%, aluminum 0.2-2.5 wt%
And at least one element selected from 0.02 to 0.25% by weight of phosphorus and at least one element selected from 0.7 to 3.5% by weight of manganese and 0.7 to 3.5% by weight of nickel. A free-cutting copper alloy comprising an alloy composition containing the following elements and the balance being zinc. 5. Copper 69-79% by weight, silicon 2.0-4.
0% by weight, lead 0.02 to 0.4% by weight, aluminum 0.1 to 1.5% by weight and phosphorus 0.02 to 0.25% by weight
A free-cutting copper alloy, comprising: an alloy composition containing zinc and the balance being zinc. 6. The method according to claim 5, further comprising at least one element selected from 0.02 to 0.4% by weight of chromium and 0.02 to 0.4% by weight of titanium. Free-cutting copper alloy. 7. Bismuth 0.02 to 0.4% by weight, tellurium 0.02 to 0.4% by weight and selenium 0.02 to 0.4%
6. The method according to claim 1, further comprising at least one element selected from the group consisting of:
Or the free-cutting copper alloy according to claim 6. 8. A heat treatment at 400 to 600 ° C. for 30 minutes to 5 hours. Free-cutting copper alloys described in 1.