JP3335002B2 - Lead-free free-cutting brass alloy with excellent hot workability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead-free free-cutting brass alloy having excellent dezincification corrosion resistance and hot workability. In particular, the brass alloy of the present invention has many cutting steps in the manufacturing process, such as water tap fittings and water fittings for general piping,
It is most suitable for use in fields where the material is required to have machinability, and even when in contact with drinking water or general industrial wastewater, the elution of Pb is required to be below specified levels. It is most suitable for a sliding member used in a corrosive environment and a general industrial sliding member that restricts the inclusion of Pb in metal powder scattered by sliding.

[0002]

2. Description of the Related Art Brass-based JIS H3250C3604 alloy and C3771 alloy, and bronze-based JIS H5111 BC are used as water faucet fittings and water fittings for general piping.
Six alloys are widely used.

[0003] Further, as in JIS H3250 C4641 alloy, Cu-Zn-S having improved dezincification corrosion resistance is provided.
An n-Pb-based alloy also exists. As a free-cutting brass containing no Pb, there is a Cu-Zn-Bi-based alloy (alloy disclosed in JP-A-5-255778). Furthermore, without Pb,
As an alloy for faucet fittings containing Sn, Cu-Zn-Sn-
There is a Bi-based alloy (JP-B 5-63536). In addition, strength and hot workability similar to ordinary brass can be expected, and Cu-Zn-Sn-Bi is used as brass containing no Pb.
-P-In alloys are known (USP No. 5,
167, 726 alloy).

On the other hand, bronze, brass, and aluminum bronze are generally known as sliding copper alloys. Among them, brass is widely used because it is most easily hot worked and inexpensive. In addition, Cu-Zn is used as a Bi-free lead-free sliding member.
-Bi-Ti-P-Sn-graphite alloys
No. 3-16456 alloy).

[0005]

Problems to be Solved by the Invention Brass JIS H3
250 C3604 alloy, C3771 alloy , and bronze-based JIS H5111 BC6 alloy both contain Pb to improve machinability, so that the machinability almost satisfies the requirements of the cutting process in the manufacturing process. ing. However, since both contain a large amount of Pb, metal vapor containing Pb at the time of high-temperature operations such as melting and casting welding, and dust containing Pb generated during cutting / grinding have an adverse effect on human bodies and the environment during production. Have given. In addition, Pb is eluted from the water-contacting portion even during use, which harms the human body and the environment through drinking water and drainage. Furthermore, when the brass-based alloy is used in the wetted portion, dezincification corrosion occurs, and the function cannot often be achieved.

[0006] The JIS H3250 C4641 alloy also contains a considerable amount of Pb, and thus cannot prevent the same lead harm as described above.

The alloy disclosed in Japanese Patent Application Laid-Open No. 5-255778 has no harm of Pb and good machinability, but causes dezincification corrosion. In addition, since it contains misch metal as an additional element, it has a disadvantage of being expensive.

[0008] The component range of the alloy of Japanese Patent Publication No. Hei 5-63536 is by weight, Cu = Bal, Zn = 5-15%, Sn
= 1 to 12%, Bi = 1.5 to 7%, and Zn
Since the content is small, the strength is low, the price is high, and the hot workability is poor.

[0009] USP No. The 5,167,726 alloy is expensive because it contains expensive In. Also, there is a Cu-Zn-Sn-Bi-P-based alloy containing no In,
P in the added component, when dissolved, combines with Fe as an impurity in the raw material to form a hard spot, which may impair machinability, or cause poor appearance or functional impairment as a product. For this reason, it is necessary to examine the raw materials to be used, and there is a disadvantage that the cost is disadvantageous.

On the other hand, brass as a sliding copper alloy is inferior in seizure resistance and machinability as it is.
% Of Pb is added to improve the characteristics. For this reason, the harm of lead as described above cannot be prevented.

Also, Japanese Patent Publication No. 63-16456 alloy is
Graphite is added to the brass-based material to improve the wear characteristics.However, in order to measure the uniform distribution of graphite, it is necessary to perform pressure solidification using a mold. There is a disadvantage that the cost is increased due to the production of a mold and the like.

As described above, each of the conventional alloys has poor machinability, resistance to dezincification corrosion, prevention of lead pollution to the human body and the environment, lacks strength, is expensive, or is hot. In all respects, such as poor workability, it was not satisfactory.

The present invention has been made in view of the above circumstances, and has improved machinability, excellent dezincification corrosion resistance and hot workability, and substantially reduces pollution of the human body and the environment by lead. It is an object of the present invention to provide a lead-free free-cutting brass alloy which can be eliminated, is inexpensive and has excellent strength. A further object of the present invention is to provide a lead-free free-cutting brass alloy which is improved in wear characteristics in addition to the above-mentioned respective characteristics and can be used as a sliding member.

[0014]

The lead-free free-cutting brass alloy according to the present invention, which is excellent in dezincification corrosion resistance and hot workability, is 22 to 45% by weight, Zn: 0.2 to 4% by weight. %, S
n: 0.3 to 3%, with the balance being Cu and impurities. Further, more preferably, by weight%, Z
n: 22-42%, Bi: 0.5-2%, Sn: 0.5-
2%, with the balance being Cu and impurities.

On the other hand, a lead-free free-cutting brass alloy further improved in wear resistance in addition to the above alloy properties is as follows: (1) by weight%, (a) Zn: 22 to 45%, Bi: 0.2%.
2-4%, Sn: 0.3-3%, and (b) N
i: 4% or less, Si: 3% or less, Al: 6% or less, M
At least one element selected from the group consisting of n: 5% or less and Sb: 1% or less is contained, with the balance being Cu and impurities.

(2) Also, in terms of% by weight, (a) Zn: 22
-45%, Bi: 0.2-4%, Sn: 0.3-3%, (b) Ni: 4% or less, Si: 3% or less,
At least one element selected from the group consisting of Al: 6% or less, Mn: 5% or less, and Sb: 1% or less;
e: 3% or less, Co: 3% or less, Ti: 3% or less, M
o: 1% or less, Cr: 1% or less, Zr: 2% or less, N
b: characterized by containing at least one element selected from the group consisting of 1% or less, with the balance being Cu and impurities.

(3) Further, more preferably, by weight%,
(a) Zn: 22 to 42%, Bi: 0.5 to 2%, Sn:
0.5 to 2%, and (b) Ni: 4% or less, S
i: 4% or less, Al: 6% or less, Mn: 5% or less, S
b: characterized by containing at least one element selected from the group consisting of 1% or less, with the balance being Cu and impurities.

(4) Or, by weight%, (a) Zn: 2
2 to 42%, Bi: 0.5 to 2%, Sn: 0.5 to 2%, and (b) Ni: 4% or less, Si: 4% or less, Al: 6% or less, Mn At least one element selected from the group consisting of: 5% or less, Sb: 1% or less;
(c) Fe: 3% or less, Co: 3% or less, Ti: 3% or less, Mo: 2% or less, Cr: 2% or less, Zr: 2% or less, Nb: 2% or less It contains at least one element, and the balance is made up of Cu and impurities.

Next, the reasons for specifying the chemical components and the amounts thereof as described above in the alloy of the present invention will be described.

(1) Zn Since Zn strengthens the matrix of this alloy, at least 2
2 % is required. However, if it exceeds 45%, a large amount of fragile γ phase is precipitated, so it is necessary to reduce the content to 45% or less. Among them, the range of 22 to 42% is preferable because of good hot workability and high strength.

(2) Sn Sn improves the dezincification corrosion resistance of brass material.
0.3% or more is required. However, if it exceeds 3%, it saturates and impairs hot workability, so it is made 0.3 to 3%. Especially, the range of 0.5 to 2% is preferable.

(3) Bi Addition of Bi improves the machinability and seizure resistance when it is 0.2% or more, but when it is too much, the toughness is reduced. Preferably, it is set to 0.5 to 2%.

(4) Ni, Si, Al, Mn groups, and
Fe, Co, Ti, Mo, Cr, Zr, Nb group Addition of Ni, Si, Al, Mn strengthens the matrix and also adds Fe, Co, Ti, Mo, Cr, Zr, Nb.
In combination with b and the like, a hard intermetallic compound is generated, and wear resistance and seizure resistance are improved. If the amount is too large, hard spots are formed, and the machinability and wear characteristics are impaired.

(5) Sb Sb improves the machinability and seizure resistance together with Bi and also improves the wear resistance, but if it exceeds 1%, the toughness is impaired.

The method for producing each of the above alloys is not particularly limited. For example, even if it is a cast material, a hot-rolled material, a cold-rolled material, or any other material to which necessary heat treatment, plastic working, cutting, or the like is added, all are included.

Pb is allowed as an impurity in a range not exceeding 0.4% by weight. In the presence of this level of Pb, P
There is no pollution problem caused by dust containing b. Further, even when the alloy of the present invention is used for drinking water,
This amount of Pb is never eluted in drinking water or wastewater and has no adverse effect on the human body or the environment.

[0027]

[Operation] (1) Pb is substantially harmless 0.4% compared to conventional free-cutting brass material which has improved machinability by adding lead.
Since it is suppressed as follows, it is possible to substantially eliminate the adverse effect of lead on the human body and the environment during production and use. (2) In order to improve the machinability, Bi is added in a range that is substantially harmless to the human body and the environment, thereby ensuring the same machinability as a free-cutting copper alloy containing lead. (3) By adding a predetermined amount of Sn, dezincification corrosion is prevented. (4) Since it is based on a brass alloy containing 22 to 45% of Zn, it is excellent in hot workability, has high strength, and can be provided at low cost.

The above-mentioned lead-free free-cutting brass alloys having excellent dezincification corrosion resistance and hot workability include Ni, Si, Al, Mn,
By adding one or more metal elements such as Sb, Fe, Co, Ti, Mo, Cr and Nb, the above (1), (2),
In addition to the functions and effects described in (3) and (4), a wear member having abrasion characteristics required for a slide member and excellent in machinability that can be used even in a corrosive environment has been completed.

[0029]

Examples (1) Test materials Table 1 shows the materials of the present invention, and Table 2 shows the materials of the comparative examples (including conventional alloys). Alloys composed of the components Nos. 1 to 29 shown in Tables 1 and 2 were melted in a high-frequency induction furnace, and cast into a billet for extrusion having a diameter of 205 × 300 L (unit: mm). At 680-780 ° C,
It was hot-extruded to φ53 × 3000 L to obtain a test material of an example of the present invention and a test material of a comparative example. Nos. 15, 16, and 24 in which cracks occurred during hot extrusion were melted again and cast into a JIS H 5113E test material by die casting to obtain a test material.

[Table 1]

[Table 2]

(2) Tensile Test and Hardness Test Each test material was machined into a JIS Z 22014 tensile test piece (with a hardness piece) and tested. Table 3 shows the results.

[Table 3]

(3) Dezincification corrosion test Each test material was machined to φ20 × 10L, and the Japan Copper and Brass Association technical standard “Dezincification corrosion test method for brass rods” (JBMA-
T-303-1988), the depth of the dezincing layer was measured, and evaluated as follows. The results are shown in Table 3.・ Dezincing layer depth: less than 10 μm ◎ ・ 〃: 10 or more to less than 100 μm ○ ・…: 100 μm or more ×

(4) Dissolution test Each test material was machined to φ20 × 150L, and the “water-supply equipment-related regulations,” specified by the Japan Water Works Association.
Rules and Examination Standards (revised in July 1983) ", measure the amount of lead elution, and set the standard elution limit at 0.0.
Passes of 2 mg / l or less were regarded as acceptable, and those exceeding 0.02 mg / l were rejected. In Table 3, "Pass" indicates "Pass" and "X" indicates "Fail".

(5) Cutting Test Each test material was machined to φ20 × 150 L, and the outer diameter portion was turned under the conditions shown in Table 4 to perform a cutting test. The machinability was evaluated as shown in FIG. 1 based on the shape of the cutting powder generated during processing. The bite shape is based on the shape shown in FIG.

[Table 4]

(6) Abrasion test Each test material was machined into the shape of a test piece (test pin) shown in FIG. 3, and a Fabry wear test was performed using the V-block shown in FIG. Was done. The wear resistance and seizure resistance were evaluated based on the wear amount and the Fabry value according to the criteria shown in Table 5.

[Table 5]

Test conditions Rotation speed: 300 rpm Sliding speed: 0.102 m / sec Specimen size: φ6.5 × 40 Lubricating oil: Turbine oil # 32 Material material: SCM 415 (HCQT) HRC = 60 Surface roughness : Test piece-2-3S, mating material-2-3S

Test method a) Abrasion resistance evaluation test A test was conducted at a load of 300 kgf for 10 minutes, the weight before and after the test was measured, and the loss on wear (mm ³ ) was calculated from the density and evaluated. The smaller the abrasion loss, the better the abrasion resistance. B) Seizure resistance evaluation test Increase the load at an initial load of 200 kgf at 38 kgf per second, test until seizure, and record the torque and load.
Load is P (Kgf), torque is T (Kgf-cm), and time is t
(Sec), and assuming that the time until burning is t ₁ (sec), the Fabry value F (Kgf · m), which is an evaluation value of burning resistance, can be obtained by the following equation. The larger the F value, the better the seizure resistance.

(Equation 1)

[0037]

The gist of the alloy of the present invention for preventing lead damage to the human body and the environment has been substantially achieved. Among conventional alloys, Bi-added free-cutting copper alloys containing no Pb include:
Certainly, the harm of Pb can be prevented, but these cannot be subjected to hot extrusion or cause dezincification corrosion, so that their production methods and applications are limited. In addition, some special elements are added, but this is because the added elements are expensive,
Uses are limited. On the other hand, the alloy of the present invention is a lead-free free-cutting copper alloy that can be hot extruded, does not cause dezincification corrosion, and is inexpensive and excellent in strength, so that there is no need to worry about lead pollution. is there.

In the present invention, in addition to these characteristics, Ni,
Al, Mn, Fe, Ti, Mo, Co, Cr, Si, N
By adding a general-purpose metal element such as b, the wear characteristics are improved and the sliding member can be used, and can be used in a corrosive environment such as seawater, which cannot be used with the conventional sliding member. It is what came to be.

[Brief description of the drawings]

FIG. 1 is a view for explaining evaluation criteria for machinability in a cutting test.

FIG. 2 is a diagram illustrating the shape of a cutting tool used in a cutting test.

FIG. 3 is a diagram illustrating the shape of a test piece used for a wear test.

FIG. 4 is a view for explaining the shape of a mating material used in a wear test.

FIG. 5 is a diagram illustrating a test method in a Fabry wear test.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kazuyuki Inagaki 1 New Arashi Nishiashiwara, Tateyama-machi, Nakashinkawa-gun, Toyama 1 Examiner at Chuetsu Alloy Casting Co., Ltd. Kengo Koyanagi (56) References JP-A-61- 133351 (JP, A) JP-A-5-255778 (JP, A) JP-B 5-63536 (JP, B2) JP-B 63-16456 (JP, B1) Patent 27263 (JP, C2) International publication 93 / 24670 (WO, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C22C 9/04

Claims (7)

(57) [Claims] 1. A weight%, Zn: 22 ~45%, Bi:
0.2% to 4%, Sn: 0.3% to 3%, with the balance being Cu and impurities, a lead-free free-cutting brass alloy having excellent dezincification corrosion resistance and hot workability. 2. A weight%, (a) Zn: 22 ~45%,
Bi: 0.2 to 4%, Sn: 0.3 to 3%, (b) Ni: 4% or less, Si: 3% or less, Al: 6%
In the following, it contains at least one element selected from the group consisting of Mn: 5% or less and Sb: 1% or less, with the balance being Cu and impurities, being excellent in dezincification corrosion resistance, hot workability, and wear resistance. Lead-free free-cutting brass alloy with excellent properties. (3) Zn: 22 to 45% by weight,
Bi: 0.2 to 4%, Sn: 0.3 to 3%, (b) Ni: 4% or less, Si: 3% or less, Al: 6% or less, Mn: 5% or less, Sb At least one element selected from the group consisting of: 1% or less, and (c) Fe: 3% or less, Co: 3% or less, Ti: 3% or less, Mo: 1% or less, Cr: 1% or less, Zr: 2% or less, Nb: At least one element selected from the group consisting of 1% or less, the balance being Cu and impurities, excellent in dezincification corrosion resistance, hot workability, and wear resistance. Excellent lead-free free-cutting brass alloy. 4. In weight%, Zn: 22-42%, Bi:
A lead-free free-cutting brass alloy containing 0.5 to 2%, Sn: 0.5 to 2%, and the balance being Cu and impurities, and having excellent dezincification corrosion resistance and hot workability. (5) Zn: 22 to 42% by weight,
Bi: 0.5 to 2%, Sn: 0.5 to 2%, and (b) Ni: 4% or less, Si: 4% or less, Al: 6%
In the following, it contains at least one element selected from the group consisting of Mn: 5% or less and Sb: 1% or less, with the balance being Cu and impurities, being excellent in dezincification corrosion resistance, hot workability, and wear resistance. Lead-free free-cutting brass alloy with excellent properties. 6.% by weight: (a) Zn: 22 to 42%;
Bi: 0.5 to 2%, Sn: 0.5 to 2%, and (b) Ni: 4% or less, Si: 4% or less, Al: 6%
Hereinafter, at least one element selected from the group consisting of Mn: 5% or less and Sb: 1% or less, (c) Fe: 3% or less, Co: 3% or less, Ti: 3% or less, Mo: 2 % Or less, Cr: 2% or less, Zr: 2% or less, Nb: at least one element selected from the group consisting of 2% or less, with the balance being dezincification corrosion resistance and heat consisting of Cu and impurities. Lead-free free-cutting brass alloy with excellent workability and wear resistance. 7. The lead-free free-cutting brass alloy according to claim 1 , wherein a Pb content is 0.4% by weight or less .