JPH07103456B2 - Method for increasing crystal grain size of copper alloy material - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for enlarging crystal grains in a copper alloy material.

[0002]

2. Description of the Related Art Conventionally, in the field of decorative materials, it has been attempted to treat a metal material so as to expose coarse crystals on its surface, and as a treatment method thereof, JP-B-38-10956. No. or Japanese Examined Shoko 38-162
As disclosed in Japanese Unexamined Patent Publication No. 20-205, a method in which an aluminum material is lightly worked (plastic deformation of about several percent), annealed at a recrystallization temperature of aluminum or higher, and then etched, or Japanese Patent Publication No. 52-13167 is used. No. or Japanese Patent Publication Sho 52-2
As disclosed in Japanese Patent No. 2338, there is known a method in which an aluminum material is buckled and curved so that it is substantially plastically worked and then annealed at a recrystallization temperature or higher.

However, these methods can be applied to aluminum materials and the like, but cannot be applied to copper alloy materials. That is, in a metal material such as aluminum having a low recrystallization temperature and a high stacking fault energy, the crystal grains can be easily coarsened, so that the crystal grains can be made sufficiently large. For example, some cold working was performed. Even if the brass material (C2600P) is annealed at a temperature higher than the recrystallization temperature (for example, 850 ° C.), the crystal grains are coarsened to about 2 mm at best.

Therefore, the applicant of the present invention has previously filed Japanese Patent Application Laid-Open No. 1-1.
As disclosed in Japanese Patent No. 36950, a method of enlarging crystal grains by subjecting a copper alloy material to appropriate plastic working and then heat treating it in a β phase generation temperature region or a temperature region in the vicinity thereof (hereinafter referred to as “ "Traditional method") was developed.
That is, this method utilizes that the β-phase crystal grains easily grow in the above temperature range, and the energy accumulated in the crystal grains is diverged by plastic deformation by performing appropriate plastic working, This is to promote the growth of crystal grains.

[0005]

However, in the conventional method, the energy accumulated in the crystal grains is only diffused to accelerate the enlargement of the crystal grains. It can only be made huge, and there are few variations in terms of decorative effects.

Moreover, when the heat treatment is repeatedly performed to make the crystal grains larger, it is necessary to perform the plastic working before each heat treatment step, so that the treatment efficiency is very poor. That is, if the copper alloy material is taken out of the furnace every time the heat treatment is finished and cold working including a cleaning step is performed, the number of steps is unnecessarily increased, the processing efficiency is deteriorated, and the cost is disadvantageous. Is. In addition, if the copper alloy material is repeatedly heat-treated at a high temperature, a large thermal strain may occur due to the properties of the copper alloy, which makes it difficult to perform plastic working, or the strain may cause uniform plastic deformation. In some cases, it may not be possible to carry out a good crystal grain enlargement treatment, and the yield will deteriorate.

Further, since it is an essential condition to perform plastic working before heat treatment, copper alloy materials such as forged products, cast products and drawn products which are difficult to plastic work are difficult to process. There is a limit to the copper alloy material that can be treated because it cannot be treated effectively.

The present invention solves such a problem in the conventional method, and makes it possible to easily and inexpensively increase the grain size of a copper alloy material regardless of its material and shape.
Moreover, crystal grains cannot be obtained by the conventional method for several tens of meters.
It is an object of the present invention to provide a crystal grain enlarging treatment method for a copper alloy material capable of enlarging to m or more.

[0009]

In order to achieve the above-mentioned object, in the method for treating crystal grains of a copper alloy material according to the present invention, in order to achieve the above-mentioned object, the copper alloy material is in a β single phase temperature range or a temperature in the vicinity thereof. An initial heating step of heating and holding the region for a predetermined time, a gradual cooling process of gradually cooling the heated copper alloy material to a predetermined temperature, and a temperature region in which the gradually cooled copper alloy material becomes a β single phase or a temperature region in the vicinity thereof. And a reheating step of heating and holding for a predetermined time. Further, in order to further increase the size of the crystal grains, it is proposed that the slow cooling step and the reheating step be alternately repeated a plurality of times after the initial heating step.

[0010]

In the initial heating step, the α-phase region is transformed into the β-phase by heating and holding the copper alloy material in the temperature region where the β-single phase is formed or in the vicinity thereof for a predetermined time. At this time, it is not always necessary to completely remove the α-phase region by heat treatment. Such heat treatment is performed using an electric furnace or the like whose temperature can be easily controlled. The heating temperature and heating time are
It is appropriately set according to the copper content, the amount of additional elements, etc. in the material to be treated. As the copper alloy material, brass or the like that can have a β phase region in a predetermined temperature region can be used in terms of material,
In addition, there is no limitation in shape, and plate shape, bar shape, line shape,
A non-processed product such as a pipe shape, a forged product made of this material, an intermediate processed product such as a deep-drawn product, a final processed product, or a cast product can be used.

In the slow cooling step, the α phase precipitates around the β grain boundary, and the amount of precipitation increases as the temperature decreases. The α phase is mainly precipitated on the (111) plane of the β phase, and the α phase density is particularly high at the β crystal grain boundary. The precipitation morphology (distribution, amount, orientation, shape) of this α phase greatly differs depending on the cooling method and the cooling end temperature, and finally the precipitation morphology greatly affects the degree of enlargement of crystal grains. The slow cooling step is usually performed subsequent to the initial heating step by controlling the furnace temperature. That is, the heated copper alloy material is cooled in the furnace. Therefore, the transition from the initial heating step to the slow cooling step and further to the reheating step can be smoothly performed without taking out the copper alloy material from the furnace, and the treatment efficiency can be significantly improved by the continuous treatment. obtain.

In the reheating step, after the slow cooling step, the temperature is raised to a temperature region where it becomes a β single phase or a temperature region in the vicinity thereof, and the temperature is maintained at that temperature.
Most of the phases disappear. At this stage, a fine α phase remains at the β grain boundary, but after that, the presence of the α phase at the β grain boundary disappears with the passage of time, and the merging of crystal grains progresses. . In other words, the small crystal grains are eaten by the mosquitoes to become huge, and at the final stage, only the crystal grains become large. This is because the α phase remaining at the β grain boundary has the effect of suppressing the β crystal grain growth, and when the pinning disappears,
This is probably because abnormal growth of β crystal grains occurs.
Therefore, the rate of temperature increase from the cooling end temperature to the reheating temperature and the heating time are also important factors in achieving the enlargement of crystal grains together with the above-described slow cooling conditions.

As described above, according to the method of the present invention, α + β → β
Giant crystal grains are obtained by the heat treatment process of α + β → β, and it can be said that this is a kind of secondary recrystallization method with phase change. As described above, the α phase precipitated at the β grain boundary has the effect of inhibiting the growth of β crystal grains, and the β phase is refined by repeating the heat treatment to increase the interfacial energy of the β phase. It is possible to realize abnormal grain growth. Therefore, by further repeating the slow cooling step and the reheating step a plurality of times, it becomes possible to further increase the size of the crystal grains, and the heat treatment conditions (heating temperature, heating time, temperature rising rate, cooling rate, cooling end temperature, annealing By appropriately changing the number of repetitions of the reheating step including the cooling step, etc.), the grain size can be changed from the same several mm as in the conventional method to several tens of mm which cannot be obtained by the conventional method and further. It can be freely controlled over a range, and a crystal grain of a desired size can be obtained.

If necessary, the final treated product may be subjected to a surface treatment such as pickling or surface polishing, and by such treatment, the crystal grains that have become huge can be remarkably exposed. At this time, further clear film treatment is applied,
The surface color may be retained. The crystal grain size does not change depending on the cooling conditions after the final reheating treatment, but it has a great influence on the surface condition such as color tone. That is, the surface condition can be changed by changing the cooling conditions. For example, a surface having a vivid metallic luster can be obtained by rapid cooling, and a surface with a calm color tone can be obtained by slow cooling.

[0015]

EXAMPLE As a first example, the copper alloy material No. 1-12
Were heat-treated under the conditions shown in Table 1 using an electric furnace. Each copper alloy material is a copper-zinc alloy (Cu: 58.6 wt%, Pb: 0.
004% by weight, Sn: 0.008% by weight, Fe: 0.0
Disk shape (diameter 70m) consisting of 11% by weight, Zn: balance
m, thickness 5 mm), a semi-continuously cast ingot (diameter 220 mm) was hot extruded (700 ° C.), and the extruded material (diameter 26 mm) was hot forged (700 ° C.). It was obtained.

Copper alloy material No. 1 to 9 and No. For No. 12, the primary heat treatment and the secondary heat treatment were continuously performed, and after the secondary heat treatment, they were taken out of the electric furnace and water-cooled. That is,
In the primary heat treatment, first, the temperature was raised at a constant rate of 18 ° C / min to 780 ° C, the heating state was maintained for 90 minutes, and then the electric furnace was controlled to cool at 1 ° C / min.
(3 ° C / min for No. 6) at a predetermined temperature (Table 1
(Cooling end temperature) shown in FIG. In the secondary heat treatment that is continuously performed after cooling the furnace, the temperature is raised at a predetermined rate (temperature rising rate shown in Table 1) and reheated to 780 ° C., and this heating state is maintained for 90 minutes, and then the copper alloy material is used. Was taken out of the electric furnace and cooled with water.

The copper alloy material No. For Nos. 10 and 11, the primary heat treatment, the secondary heat treatment and the tertiary heat treatment were performed, and after the tertiary heat treatment, they were taken out of the electric furnace and water-cooled. That is,
First, the temperature is raised at a constant rate of 18 ° C / min to reach a predetermined temperature (N
o. For No. 10, 700 ° C., No. 10 7 for 11
After heating to 80 ° C., this heating state is maintained for a predetermined time (No. 1).
No. 0 is 60 minutes, No. No. 11 is maintained for 90 minutes), and then at a predetermined cooling end temperature (N
o. For No. 10, 550 ° C., No. 10 5 for 11
The furnace was cooled to 10 ° C. After such a primary heat treatment, No.
Cooling end temperature (500 ° C.) and No. 10 1
The secondary heat treatment was performed under the same conditions as the primary heat treatment except for the heating rate (4 ° C./min) for No. 1, followed by reheating to 780 ° C. at a heating rate of 4 ° C./min. After being kept for a minute, the copper alloy material was taken out of the electric furnace and cooled with water.

As a comparative example, the same copper alloy material No. Heat treatment was performed on 13 to 19 as shown in Table 1. That is, the copper alloy material No. 13 to 19,
In the electric furnace, the temperature was raised at a constant rate of 18 ° C./min to heat to a predetermined temperature (heating temperature shown in Table 2), and the heating state was maintained for 90 minutes (1000 minutes for No. 16) and then the electric furnace. I took it out of. After that, No. 13-
With respect to No. 16, the treatment was finished by cooling with water. On the other hand, No.
Samples 17 to 19 were rapidly cooled to 30 ° C. by water cooling or air cooling, reheated to 780 ° C. in an electric furnace, maintained in the heated state for 90 minutes, and then taken out from the electric furnace. And No. The samples 17 and 18 were cooled with water and the treatment was completed. In addition, No. Regarding No. 19, after being rapidly cooled to 30 ° C. by water cooling, it was reheated to 780 ° C. again in an electric furnace, maintained in the heated state for 90 minutes, taken out from the electric furnace and water cooled.

Then, each copper alloy material No. 1-1
For No. 9, the macrostructure was exposed with nitric acid and the grain size was measured. The results are shown in Table 1. In the comparative example, only a few mm of huge crystal grains were obtained, but in the example (excluding No. 12),
A crystal grain which was enlarged to several tens of mm was obtained. In particular, N
o. In 11, the material diameter was increased to 70 mm or more,
There were no grain boundaries.

[0020]

[Table 1]

[0021]

[Table 2]

As the second embodiment, the copper alloy material No.
20 to 25 were heat-treated under the conditions shown in Table 2, respectively. Each copper alloy material is a copper-zinc alloy (Cu: 60.0 wt%, Pb: 0.01 wt%, S
It is a cylindrical (diameter 35 mm, length 50 mm) cast product made of n: 0.01% by weight, Fe: 0.02% by weight, Zn: the balance.

That is, each copper alloy material No. 20-25
Is heated at a constant rate of 18 ° C / min in an electric furnace for 8
After heating to 10 ° C and maintaining this heating state for 90 minutes, the furnace was cooled to a predetermined temperature (cooling end temperature shown in Table 2) at a cooling rate of 1 ° C / min (3 ° C / min for Nos. 22 and 25). Chilled After cooling the furnace, the temperature was raised at a predetermined rate (temperature rising rate shown in Table 2) and reheated to 810 ° C., and this heating state was maintained for 90 minutes. And No. For 20 to 24, the treatment was completed by taking them out from the electric furnace and cooling them with water.
On the other hand, No. For No. 25, the furnace was cooled to 520 ° C. at 1 ° C./min, and the temperature was raised to 81 ° C. at a rate of 4 ° C./min.
After heating again to 0 ° C. and maintaining this heating state for 90 minutes, it was taken out of the electric furnace and cooled with water.

As a comparative example, No. The same copper alloy material No. 20 to 25. Heat treatment was performed on Nos. 26 to 29 as shown in Table 2. That is, the copper alloy material No. 26 ~
In the electric furnace, the temperature of No. 29 was raised at 18 ° C./min to 810 ° C., and the heating state was maintained for 90 minutes (No. 2).
No. 7 was kept for 1000 minutes) and then taken out of the electric furnace. After that, No. With respect to Nos. 26 and 27, the treatment was terminated by cooling with water. On the other hand, No. For 28 and 29,
After being rapidly cooled to 30 ° C. by water cooling or air cooling, it was reheated to 810 ° C. in the electric furnace, maintained in the heated state for 90 minutes, and then taken out from the electric furnace. And No. Two
No. 8 was cooled with water and the treatment was completed. In addition, No. Two
Regarding No. 9, after being rapidly cooled to 30 ° C. by air cooling, it was reheated again to 810 ° C. in an electric furnace,
After maintaining for 0 minutes, it was taken out of the electric furnace and cooled with water.

Then, each copper alloy material No. 20 ~
For No. 29, the macrostructure was exposed with nitric acid and the grain size was measured. The results are shown in Table 2,
In the comparative example, only huge crystal grains of about several mm were obtained, but in the example, crystal grains enlarged to several tens of mm were obtained. In particular, No. In Nos. 24 and 25, the material was made larger than the material diameter (35 mm) and there was no grain boundary at all.

As is clear from Tables 1 and 2, the secondary heat treatment (slow cooling and reheating) is required to make the crystal grains extremely large only by performing the primary heat treatment, and to make them ultra-large in size of several tens mm or more. ) Is understood to be necessary. Also,
Comparative Example No. 17-19 and No. From 28 and 29, no matter how many times the heat treatment is repeated, slow cooling (furnace cooling) between heating steps
It is understood that if it is not done, it cannot be made huge. Further, in No. 1 in the first embodiment. Although the crystal grain size of 12 is 3 mm, this indicates that the size can be increased to several mm by changing the heat treatment condition (in this example, the cooling end temperature).

As described above, according to the method of the present invention, extremely large crystal grains which cannot be obtained by the conventional method can be obtained, and the grain size can be changed to several mm by changing the heat treatment conditions. It is possible to freely control over a wide range from to several tens of millimeters.

As a third embodiment, copper alloy material No. Thirty
Is heated at a constant rate of 18 ° C./min to 810 ° C., this heating state is maintained for 90 minutes, and then 1 ° C./m
Furnace cooling to 540 ° C with in, followed by a heating rate of 4 ° C / m
Reheat to 810 ° C for 90 minutes and hold for 1 more
After furnace cooling to 540 ° C at a rate of 4 ° C / min.
It was heated again to 810 ° C. for min and held for 90 minutes, taken out from the electric furnace and cooled with water.

As a comparative example, the copper alloy material No. 31
Was heat-treated under the same conditions as the above-mentioned primary heat treatment. That is,
Copper alloy material No. 31 is heated at 18 ° C./min to 8
After heating to 10 ° C. and maintaining this heating state for 90 minutes, it was taken out of the electric furnace and cooled with water.

Each copper alloy material No. 30 and 31 are copper-zinc alloys (Cu: 6) that form a β single phase at about 790 ° C.
0.23% by weight, Pb: 0.02% by weight, Sn: 0.0
Commercially available C2801P-H plate (width 365 mm, length 35) consisting of 1% by weight, Fe: 0.03% by weight, Zn: balance.
A rectangular plate having a thickness of 0 mm and a thickness of 2 mm was used.

Then, each heat-treated copper alloy material No. Three
Regarding 0 and 31, the macrostructure was expressed with nitric acid to measure the crystal grain size, and JIS Z2201 No. 5 test pieces were sampled to test for tensile strength, proof stress, and elongation. The measurement and test results are shown in Table 3. In addition, the test piece is divided into the one parallel to the rolling direction and the one perpendicular to it.
No. Sample No. 30 was sampled so that crystal grain boundaries were not included in the parallel part of the test piece and its vicinity.

[0032]

[Table 3]

As is clear from the measurement results of Table 3, according to the present invention, the grain size is 1 depending on the shape of the copper alloy material.
It is understood that it can be made extremely large up to 00 mm or more.

Further, as is clear from the test results of Table 3, the processing material No. 30 is the treated material N of the comparative example
o. Compared with No. 31, there is almost no difference in tensile strength and proof stress, but elongation is four times or more, and ductility is remarkably improved. This is because the crystal grain boundaries are lost due to the enlargement of the crystal grains, and a single crystal is formed. That is, the lack of mechanical properties such as ductility, which is a fatal defect in a copper alloy having a β-phase structure, is caused by enlarging the crystal grain boundary beyond the extent that it can be lost in relation to the shape of the copper alloy material. , Can be effectively resolved.

Therefore, the copper alloy material treated by the method of the present invention is not only used as a decorative material, but also as a structural material requiring mechanical strength or a copper-based shape memory alloy having a β-phase structure at high temperature. It can be preferably used as a material and the like, and is expected to greatly expand its applications.

As the fourth embodiment, the copper alloy material No.
32 to 35 were heated to 800 ° C. at a temperature rising rate of 18 ° C./min and held for 90 minutes, then cooled to 540 ° C. at a cooling rate of 1 ° C./min, and further heated at a temperature rising rate of 4 ° C./min to 80 ° C.
It was reheated to 0 ° C. and held for 90 minutes, then taken out of the electric furnace and cooled with water. Copper alloy material No. Nos. 32 to 35 are brass extruded materials having the compositions shown in Table 4, each having a diameter of 100 m.
m, 150 mm long casting rod, diameter 95 mm, length 12
It was obtained by carrying out hot extruding (700 ° C.) into a rod shape having a diameter of 15 mm after chamfering to 0 mm.

Each processed copper alloy material No. 32
For ~ 35, the macrostructure was exposed with nitric acid and the grain size was measured. The measurement results are as shown in Table 4.

As is apparent from Table 4, it is understood that the crystal grains can be made extremely large regardless of the material of the copper alloy material, and in particular, a third element such as Ni or Al is contained. It is understood that even with the existing copper alloy, if the structure is such that it becomes a β single phase at high temperature, the crystal grains can be made extremely large. Of course, it will be understood that by making a judgment including the above-mentioned examples, it is possible to realize super-large crystal grains regardless of the shape of the copper alloy material.

[0039]

[Table 4]

[0040]

As can be easily understood from the above description, according to the method of the present invention, it is possible to obtain extremely enlarged crystal grains which cannot be obtained by the conventional method, and the heat treatment conditions are set. It can be changed from a few mm to 100
It is possible to obtain a copper alloy material having a desired crystal grain size in a very wide range of mm or more.

Therefore, there are many decorative variations due to the huge crystal plane, and it can be used for a wide range of purposes such as wall materials for decoration of buildings, other general decorative materials, various accessories, crafts, etc. It is possible to provide a highly decorative copper alloy material.

Moreover, the deficiency of mechanical properties (ductility, etc.), which is a fatal defect of the copper alloy material, can be eliminated by turning the crystal grains into single crystals. Therefore, the copper alloy material obtained by the present invention is not only used as a decorative material, but also in a field that has not been used because of the lack of mechanical properties as described above (for example, as a structural material or a β-phase structure at high temperature). Copper-based shape memory alloy materials, etc.), which are expected to greatly expand the applications.

Further, according to the present invention, since there is no need for plastic working as in the conventional method, there is no limitation on the material and shape of the copper alloy material that can be processed, and moreover, continuous processing in a furnace is possible, Processing efficiency and yield can be significantly improved as compared with the method, and extremely economical and efficient processing can be performed.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshinori Tsuji 8-374, Sanpo-cho, Sakai City, Osaka Prefecture Sanpo Shindoku Kogyo Co., Ltd. (56) Reference JP-A-1-136950 (JP, A)

Claims (2)

[Claims] 1. An initial heating step of heating and holding the copper alloy material in a temperature region where it becomes a β single phase or a temperature region in the vicinity thereof for a predetermined time, and a slow cooling step of gradually cooling the heated copper alloy material to a predetermined temperature. A method of enlarging crystal grains of a copper alloy material, comprising: a reheating step of heating and holding the gradually cooled copper alloy material in a temperature region where it becomes a β single phase or a temperature region in the vicinity thereof for a predetermined time. 2. The method for enlarging crystal grains of a copper alloy material according to claim 1, wherein the slow cooling step and the reheating step are alternately repeated a plurality of times after the initial heating step.