JP2000119778A - Method and equipment for manufacturing brass and brass material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further improve the machinability of a brass material, particularly a brass material securing machinability in dependence on a hardness difference between α-phase and γ-phase grains, and to provide a method and equipment for manufacturing such a brass material. SOLUTION: Because this brass has >=2.5 wt.% Pb content, 68-94% area ratio of α-phase, 0-10% area ratio of β-phase, and 6-22% area ratio of γ-phase, strength is secured in dependence on the γ-phase and SCC resistance is secured in dependence on the presence of the plural phases as well as machinability is secured in dependence on a hardness difference between the grain boundaries of the α- and γ-phases. It is investigated that, in particular, regulation of area ratio of the γ-phase to 6-22% ts best suited for securing machinability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brass material, a method for producing the same, and a production facility.

[0002]

2. Description of the Related Art Conventionally, as a method for improving the machinability of a brass material, a method relying on the β phase as shown in C3604 is known. There was a problem that the SCC resistance was poor.

[0003] Therefore, the applicant of the present invention has proposed a crystal structure of α + γ phase, which depends on the hardness difference between α and γ phase particles.
WO98 / 10106 has previously proposed that a cutting resistance index of 80 or more based on a free-cutting brass bar according to 3604 can be ensured, and that strength and SCC resistance can also be ensured.

[0004] However, it is difficult to say that the crystal structure of the α + γ phase has been sufficiently studied on the optimum crystal phase ratio and the optimum manufacturing method for improving the machinability.

The present invention is directed to a brass material, particularly a brass material which secures machinability depending on a difference in hardness between α and γ phase particles, further improving the machinability, and a method for producing such a brass material. The purpose is to provide manufacturing equipment.

[0006]

The brass according to the present invention has a Pb content of 2.5 wt% or more and an α-phase area ratio of 68 to 94%, preferably 76 to 94%.
92%, area ratio of β phase is 0 to 10%, preferably 0 to 10%.
6%, the area ratio of the γ phase is 6 to 22%, preferably 8 to 1
Since it is 8%, not only the cutability is ensured depending on the hardness difference between the α and γ phase grain boundaries, but also the strength is ensured depending on the γ phase,
SCC resistance is ensured depending on the existence of multiple phases.

In particular, it has been found that setting the area ratio of the γ-phase to 6 to 22%, preferably 8 to 18%, is optimal for ensuring the machinability.

Also, the area ratio of the β phase is 0 to 10%, preferably 0 to 6%, and it is not necessary to completely eliminate the β phase, so that the production restriction is small.

[0009] In a preferred embodiment, the average crystal grain size of the α phase is set to 15 µm or less, so that machinability, strength, and the like are improved.
Both SCC resistance can be improved.

More specifically, (1) a 0.2% proof stress or yield stress of 300 N / mm2 or more while securing a cutting resistance index of 90 or more based on a free-cutting brass bar in accordance with C3604; A cutting resistance index of 90 or more based on a free-cutting brass bar according to industrial standard JIS C-3604, and (3)
When a brass cylindrical sample is exposed to an ammonia atmosphere on a 14% ammonia aqueous solution for 24 hours while applying a load, the sample can satisfy the SCC resistance of not more than 180 N / mm 2, at which the sample does not crack.

[0011] More preferably, the Sn concentration in the γ phase is 8w.
By setting the content to t% or more, the dezincification corrosion resistance can be improved. When the β phase exists, the Sn concentration in the β phase is desirably 1.8 wt% or more.

Specifically, (4) When a zinc removal corrosion test is performed in accordance with the Japan Copper and Brass Association technical standard JBMA T-303, when the maximum zinc removal depth direction is parallel to the machining direction, the maximum zinc removal It is possible to have corrosion resistance that satisfies at least one of the condition that the depth is 100 μm or less, and the maximum dezincing penetration depth direction is perpendicular to the processing direction and the maximum dezincing depth is 70 μm or less. .

The brass material having the above crystal structure is
A brass material having a Pb content of 2.5% by weight or more, for example, an apparent Zn content of 37 to 46% by weight is used for 40%
It is manufactured by a manufacturing method having an annealing step of holding for 10 minutes or more (1 to 2 hours in a case of a temperature range of 460 ° C. or less) in a temperature range of 0 to 520 ° C.

The annealing step is not necessarily performed at 400
Even if the temperature is not in the temperature range of ５520 ° C., the β phase is not stably present and the γ phase is stably present. Is 6
% Or less, and may be in a temperature range in which the area ratio of the γ phase can be 6% or more, preferably 8% or more.

Here, the term "apparent Zn content" means that A is Cu content [wt%], B is Zn content [wt%], and t is the third element (for example, Sn). Z
When n equivalents and Q are the content of the third element [wt%], “{(B + t · Q) / (A + B + t · Q)} × 10
0 ”is used.

In order to improve the dezincification corrosion resistance, the brass material contains Sn in an amount of 0.5 to 7% by weight, preferably 0.1 to 7% by weight.
It is preferable to contain 9 to 2% by weight.

More preferably, prior to the annealing step, P
A brass material having a b content of 2.5 wt% or more and an apparent Zn content of 37 to 46 wt% is hot-extruded at a temperature of 650 ° C. or less and a cross-sectional reduction rate of 90% or more, and is extruded from brass. By having an extruding step for making the crystal grain size, the crystal grain size can be reduced.

Note that the extrusion step is not always 650
The temperature and the cross-sectional reduction rate at the time of hot extrusion such that the crystal grain size of the brass extruded product becomes 15 μm or less may be used even if the temperature is not more than 90 ° C. and the cross-sectional reduction rate is not 90% or more.

More preferably, after the extrusion step,
The brass extruded product is heated to 0.4 K /
By having a cooling step of cooling in seconds or more, it is possible to prevent the crystal once refined from becoming coarse.

According to the present invention, it is also provided that the Pb content is 2.5 wt.
% Or more, and the apparent Zn content is 37 to 46 wt.
% Brass material is hot-extruded to produce a brass extruded product, and at the time of hot extrusion, the extrusion step of controlling the temperature and the reduction rate of the area to reduce the crystal grain size, and after the extrusion step, An extruded product is held for a predetermined time in a temperature range where the β phase is not stably present and the γ phase is stably present, and an annealing step of decreasing the area ratio of the β phase and increasing the area ratio of the γ phase, After the annealing step, a cooling step of cooling the brass extrudate to 400 ° C. or less, and after the cooling step, the average crystal grain size of the α phase is 1
5 μm or less, β phase area ratio is 10% or less, preferably 6% or less, γ phase area ratio is 6% or more, preferably 8%
It is characterized by having the above crystal structure.

Preferably, the Sn content of the brass material is 0.5
-7 wt%, preferably 0.9-2 wt%, so that the Sn concentration in the γ phase is 8 wt% after the cooling step.
Or more.

Also, a brass material having a Pb content of 2.5 wt% or more and an apparent Zn content of 37 to 46 wt% is hot-extruded to produce a brass extruded product. Temperature, the extrusion step of controlling the cross-sectional reduction rate to refine the crystal grain size, and after the extrusion step, the extruded brass is subjected to γ without β phase being stably present.
Holding the phase in a temperature range where the phase is stably present for a predetermined time, reducing the area ratio of the β phase to increase the area ratio of the γ phase, and after the annealing step, extruding the brass material for 4 hours.
A cooling step of cooling the temperature to 00 ° C. or less,
After the cooling step, the Japanese Industrial Standard JIS C-3604
And a 0.2% proof stress or a yield stress of 300 N / mm2 or more based on a free-cutting brass bar according to JIS.

Further, a brass material having a Pb content of 2.5 wt% or more and an apparent Zn content of 37 to 46 wt% is hot-extruded to produce a brass extruded product and hot-extruded. Temperature, the extrusion step of controlling the cross-sectional reduction rate to refine the crystal grain size, and after the extrusion step, the brass extruded product is a temperature at which the β phase is not stably present and the γ phase is stably present. Area for a predetermined time, β
An annealing step of reducing the area ratio of the phase to increase the area ratio of the γ phase, and after the annealing step, a cooling step of cooling the brass extruded product to 400 ° C. or less, and after the cooling step, Standard JIS C-36
A cutting resistance index of 90 or more based on a free-cutting brass bar according to No. 04, and a maximum value at which a cylindrical sample of brass is not cracked when exposed to an ammonia atmosphere on a 14% aqueous ammonia solution for 24 hours while applying a load. Stress is 180N / m
The SCC resistance of not less than m2 can be satisfied.

According to the present invention, the Pb content is 2.5 wt.
% Or more, and the apparent Zn content is 37 to 46 wt.
%, Sn content is 0.5 to 7% by weight, preferably 0.9%
~ 2wt% brass material is hot-extruded to produce a brass extruded product, and at the time of hot-extrusion, the temperature and cross-section reduction rate are controlled to reduce the crystal grain size, and after the extrusion step, The brass extruded product is kept for a predetermined time in a temperature range where the β phase is not stably present and the γ phase is stably present, and an annealing step of decreasing the β phase area ratio and increasing the γ phase area ratio is performed. And a cooling step of cooling the brass extruded product to 400 ° C. or less after the annealing step.
90 based on a free-cutting brass bar according to IS C-3604
The above cutting force index and the Japan Copper and Brass Association technical standard JBMA
When a dezincification corrosion test in accordance with T-303 is performed, if the maximum dezincification depth direction is parallel to the processing direction, the maximum dezincification depth is 100 μm or less, and the maximum dezincification depth direction is processed. When it is perpendicular to the direction, it can have corrosion resistance that satisfies at least one of the conditions of a maximum dezincing depth of 70 μm or less.

In the above manufacturing method, the Pb content is 2.5 wt% or more, and the apparent Zn content is 37 wt.
~ 46 wt% of brass material can be accepted, and the brass material is heated at a temperature range of 400 to 520 ° C for 10 minutes or more (46%).
In the case of a temperature range of 0 ° C. or lower, it can be realized by a brass material manufacturing facility having a device capable of holding for 1 to 2 hours.

Preferably, a brass material having a Pb content of 2.5% by weight or more and an apparent Zn content of 37 to 46% by weight can be received, and the temperature at the time of extrusion is 48%.
An extruder for hot-extruding a brass extruded product under the conditions of 0 to 650 ° C. and a cross-sectional reduction rate of 90% or more during extrusion, and a brass extruded product can be received. It has a device capable of holding for 10 minutes or more (1-2 hours in the case of a temperature range of 460 ° C. or less) in a temperature range of 〜520 ° C. It is desirable to have a device that cools until:

[0027]

Embodiments of the present invention will be described in detail below. 1 and 2 show Examples 1 and 2 according to the present invention and Comparative Example 1.
3 is a table showing various comparisons with Tables 1 to 3.

The term "apparent Zn (content) content" in FIG. 2 means that A is Cu content [wt%], B is Zn content [wt%], and t is a third element (for example, When Zn equivalent of Sn) and Q of the third element are the content [wt%], “{(B + tQ) / (A + B + tQ)} × 1
00 ”.

In FIG. 1, corrosion resistance (dezincification corrosion resistance)
In the dezincification corrosion test according to the Japan Copper and Brass Association Technical Standard (JBMA T-303), the maximum dezincification depth is 100 μm or less when parallel to the processing direction, and 70 μm or less when perpendicular to the processing direction. And those that did not meet these criteria were marked as x.

The machinability was measured using a free-cutting brass bar (JIS C3
If the cutting resistance index based on 604) is a bar,
Less than was rated as x, 80 or more as ○, and 90 or more as ◎.

The cutting resistance index will be described in detail with reference to FIG. 3. In the cutting test, the peripheral surface of the round bar-shaped sample 1 is turned on a lathe at two different speeds of 100 [m / min] and 400 [m / min]. While cutting, the main component force Fv was measured. The cutting resistance index is a free-cutting brass bar that is said to have the best machinability for the main component force (Japanese Industrial Standard JIS C-3604).
Is the percentage of the main component. (The cutting resistance index for each cutting speed was averaged.)

Further, the SCC resistance is as follows:
Stress 180 in ammonia atmosphere on aqueous ammonia solution
When exposed for 24 hours while applying a load of N / mm2,
When the sample was broken, it was evaluated as x, and when it was not broken, it was evaluated as ○.

As shown in FIG. 4, the SCC resistance test was carried out by exposing the cylindrical sample 3 to the NH 3 vapor atmosphere for 24 hours in a state where a load was applied vertically to the cylindrical sample 3 in the glass digitizer 2. Was investigated.

As can be seen from FIGS.
Has a high Sn content and an optimum range of the area ratio of the γ phase of 8 to 15%, so that all the characteristics are excellent.

On the other hand, in Comparative Examples 1 and 3, although the corrosion resistance was good due to the large amount of Sn added, the SCC resistance was inferior due to the small area ratio of the γ phase and the particle size was large, and the soft α phase was large. Because it is too much, it is inferior in 0.2% proof stress and machinability.

The reason why Comparative Example 1 is slightly superior in machinability is that the β and γ phases are more or less precipitated.

Next, Comparative Example 2 is inferior in corrosion resistance due to a small amount of Sn and a large amount of β phase, but inferior in SCC resistance due to a small area ratio of γ phase and a large particle diameter, although the cutability is good due to the large β phase. ing.

Here, the crystal structures as in Examples 1 and 2 are obtained by the manufacturing method shown in FIG.

That is, Examples 1 and 2 are Comparative Examples 1 to 3.
Extrusion is performed at a lower temperature (580 ° C., 610 ° C.) than in the comparative example, so that a small crystal grain size shown in FIG. 1 is obtained.
° C; the γ-phase is stably precipitated, but the β-phase is annealed for a long time (2 h) in a temperature range in which the γ-phase is not stably present). As shown in FIG. The area ratio of the β phase can be reduced.

To supplement the annealing, if the annealing temperature is too high, the β phase increases, and if the annealing temperature is too low, the rate of transformation from the β phase to the α and γ phases slows down. is there. (In case of temperature range below 460 ° C, 1-2 hours)

If the annealing time is less than 10 minutes, the β phase becomes 1
When the annealing time is 10 minutes or more, the β phase becomes 10% or less and the γ phase becomes 6% or more, and when the annealing time exceeds 1 hour, the γ phase becomes spherical. It is recognized, thereby improving 0.2% proof stress and machinability. (In the case of a temperature range of 460 ° C. or lower, annealing for 1 hour or more is preferable because the transformation speed is low.)

Subsequently, although not shown in FIG. 1, Examples 1 and 2 satisfy the following erosion corrosion resistance.

FIG. 5 shows a method of the erosion corrosion resistance test. In the erosion corrosion resistance test, as shown in FIG. 5, a cylindrical sample 5 having an orifice 4 therein was used, and water was flowed through the orifice 4 at a flow rate of 40 m / sec.
4.9 × 105 Pa (5 kg /
The tightening torque to the resin stopper 6 required for sealing the orifice 4 under a water pressure of 2 cm 2 was measured.

The results of the test in FIG. 5 are as shown in FIG. 6, and Examples 1 and 2 obtained better characteristics than Comparative Examples 1 to 3.

[Brief description of the drawings]

FIG. 1 is a comparison table (crystal structure and characteristics) between Examples 1 and 2 of an embodiment according to the present invention and Comparative Examples 1 to 3.

FIG. 2 is a comparison table (composition, production method) between Examples 1 and 2 and Comparative Examples 1 to 3.

FIG. 3 is an explanatory diagram of a cutting test of the embodiment.

FIG. 4 shows stress corrosion cracking resistance (SCC resistance) of the embodiment.
Illustration of test

FIG. 5 is an explanatory diagram of an erosion corrosion resistance test of the same embodiment.

FIG. 6 shows a result of an erosion corrosion resistance test of the same embodiment.

[Explanation of symbols]

1 ... sample, 2 ... glass digitizer, 3 ... cylindrical sample,
4: Orifice, 5: cylindrical sample, 6: resin stopper

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22F 1/00 640 C22F 1/00 640A 683 683 684 684C 691 691B 691C 692 694Z 694 694B 694A

Claims (19)

[Claims] (1) a Pb content is 2.5 wt% or more;
The area ratio of the α phase is 68 to 94%, and the area ratio of the β phase is 0 to
Brass having an area ratio of 10% and a γ phase of 6 to 22%. 2. The brass according to claim 1, wherein the average crystal grain size of the α phase is 15 μm or less. 3. The brass according to claim 1, wherein the Sn concentration in the γ phase is 8 wt% or more. 4. The composition according to claim 1, wherein the Pb content is at least 2.5 wt%.
A method for producing a brass material, comprising an annealing step of holding a brass material having an apparent Zn content of 37 to 46 wt% in a temperature range of 400 ° C to 520 ° C for 10 minutes or more. 5. The brass material contains 0.5 to 7 wt% of Sn.
The method for producing a brass material according to claim 4, wherein the brass material is contained. 6. An apparent Z value prior to said annealing step.
The brass material whose n content is 37-46 wt% is 650
The method for producing a brass material according to claim 4 or 5, further comprising an extruding step of hot-extruding the brass extruded product at a temperature of not more than 0 ° C and a cross-sectional reduction rate of 90% or more. 7. Prior to the annealing step, the apparent Z
An extruding step in which a brass material having an n content of 37 to 46 wt% is hot-extruded to produce a brass extruded product, and the temperature and the cross-sectional reduction rate during hot extrusion are controlled to reduce the crystal grain size to 15 μm or less. The method for producing a brass material according to claim 4, comprising: 8. A Pb content of 2.5 wt% or more,
A brass material having an apparent Zn content of 37 to 46 wt% is maintained for a predetermined time in a temperature range in which the β phase is not stably present and the γ phase is stably present, and the area ratio of the β phase is 10%. Less than,
A method for producing a brass material, comprising an annealing step of setting an area ratio of a γ phase to 6% or more. 9. The brass material contains 0.5 to 7 wt% of Sn.
The method for producing a brass material according to claim 8, wherein the brass material is contained. 10. Prior to the annealing step, a brass material having an apparent Zn content of 37 to 46% by weight is prepared by adding 65% by weight to a brass material.
The method for producing a brass material according to claim 8 or 9, further comprising an extrusion step of hot-extruding at a temperature of 0 ° C or less and a cross-section reduction rate of 90% or more to produce an extruded brass product. 11. Prior to the annealing step, a brass material having an apparent Zn content of 37 to 46% by weight is hot-extruded to produce a brass extruded product, and a temperature and a cross-sectional reduction rate during the hot extrusion. Controlling the crystal grain size to 15 μm
The method for producing a brass material according to claim 8 or 9, further comprising an extruding step. 12. A brass material having a Pb content of 2.5 wt% or more and an apparent Zn content of 37 to 46 wt% is hot-extruded to produce a brass extruded product. And an extrusion step of controlling the cross-sectional reduction rate to refine the crystal grain size.After the extrusion step, the extruded brass is heated to a temperature at which the β phase is not stably present and the γ phase is stably present. Holding for a predetermined time in the zone, an annealing step of reducing the area ratio of the β phase to increase the area ratio of the γ phase, and after the annealing step, a cooling step of cooling the brass extruded product to 400 ° C. or less. Having an average crystal grain size of the α phase of 15 μm or less, β
A method for producing a brass material having a crystal structure in which the area ratio of a phase is 10% or less and the area ratio of a γ phase is 6% or more. 13. The brass material having a Sn content of 0.5 to 0.5.
7 wt%, and after the cooling step,
The method for producing a brass material according to claim 12, wherein the n concentration is 8 wt% or more. 14. A brass material having a Pb content of 2.5 wt% or more and an apparent Zn content of 37 to 46 wt% is hot-extruded to produce a brass extruded product. And an extrusion step of controlling the cross-sectional reduction rate to refine the crystal grain size.After the extrusion step, the extruded brass is heated to a temperature at which the β phase is not stably present and the γ phase is stably present. Holding for a predetermined time in the zone, an annealing step of reducing the area ratio of the β phase to increase the area ratio of the γ phase, and after the annealing step, a cooling step of cooling the brass extruded product to 400 ° C. or less. Having a cutting resistance index of 90 or more based on a free-cutting brass bar according to Japanese Industrial Standard JIS C-3604 after the cooling step,
A method for producing a brass material satisfying a 0.2% proof stress or a yield stress of 300 N / mm2 or more. 15. A brass material having a Pb content of 2.5% by weight or more and an apparent Zn content of 37 to 46% by weight is hot-extruded to produce a brass extruded product. And an extrusion step of controlling the cross-sectional reduction rate to refine the crystal grain size.After the extrusion step, the extruded brass is heated to a temperature at which the β phase is not stably present and the γ phase is stably present. Holding for a predetermined time in the zone, an annealing step of reducing the area ratio of the β phase to increase the area ratio of the γ phase, and after the annealing step, a cooling step of cooling the brass extruded product to 400 ° C. or less. Having a cutting resistance index of 90 or more based on a free-cutting brass bar according to Japanese Industrial Standard JIS C-3604 after the cooling step,
When a cylindrical sample of brass is exposed to an ammonia atmosphere on a 14% aqueous ammonia solution for 24 hours while applying a load, the sample is not broken and has a maximum stress of 180 N / mm 2 or more. Production method. 16. A brass material having a Pb content of 2.5 wt% or more, an apparent Zn content of 37 to 46 wt%, and an Sn content of 0.5 to 7 wt% is hot-extruded. Extruding step of making the brass extruded product, controlling the temperature at the time of hot extrusion and reducing the cross-sectional reduction rate to refine the crystal grain size, and after the extruding step, the brass extruded product has a stable β phase. Holding for a predetermined time in a temperature range in which the γ phase is stably present, and reducing the area ratio of the β phase to increase the area ratio of the γ phase; and, after the annealing step, extruding the brass material for 400 hours. A cooling step of cooling to a temperature of not more than 90 ° C. or less, and after the cooling step, a cutting resistance index of 90 or more based on a free-cutting brass bar according to Japanese Industrial Standard JIS C-3604, and a technical standard JBM When performing a dezincification corrosion test according to AT-303, when the maximum dezincification penetration depth direction is parallel to the processing direction, the maximum dezincification depth is 100 μm.
m or less, and a method for producing a brass material having corrosion resistance that satisfies at least one of the following conditions: when the maximum dezincing penetration depth direction is perpendicular to the processing direction, the maximum dezincing depth is 70 μm or less. . 17. A brass material having a Pb content of 2.5 wt% or more and an apparent Zn content of 37 to 46 wt% can be received, and the brass material is subjected to a temperature range of 400 to 520 ° C. Production equipment for brass materials with equipment that can hold for more than 10 minutes. 18. A brass material having a Pb content of 2.5 wt% or more and an apparent Zn content of 37 to 46 wt% can be received, and the temperature at the time of extrusion is 480 to 480.
An extruder for hot extrusion under conditions of 650 ° C. and a cross-sectional reduction rate of 90% or more during extrusion to produce a brass extruded product; and an extruder capable of receiving the brass extruded product; A brass material manufacturing facility having an apparatus capable of holding a temperature in a temperature range of 520 ° C. for 10 minutes or more. 19. The brass material manufacturing equipment according to claim 18, further comprising a device for cooling the brass extruded product coming out of the extruder to 400 ° C. or less.