KR101045080B1 - A high cutting copper alloy with improved strength and ductility - Google Patents

Abstract

The present invention relates to a high-cut copper alloy containing zinc (Zn), calcium (Ca) or calcium and silicon (Si) and having improved strength and ductility by adding a small amount of cast grain fine material.

The high-cut copper alloy with improved strength and ductility according to the present invention comprises copper (Cu), zinc (Zn), calcium (Ca), silicon (Si) and cast grain fine materials. More specifically, the copper (Cu) is 57.0 to 59.4 wt%, zinc (Zn) is 40 wt%, calcium (Ca) is 0.5 to 1.0 wt%, silicon (Si) is included less than 2.0 wt%, The remainder is a cast granular fire. In addition, the cast granular fine material includes 20 to 100 ppm of phosphorus (P) and 10 to 80 ppm of zirconium (Zr). The copper alloy configured as described above has the advantage that not only the workability is improved but also the strength and workability are improved.

High strength, high cutting, calcium, silicon, cast granules, rolling, copper alloy

Description

A high cutting copper alloy with improved strength and ductility}

1 is an optical micrograph of a conventional copper alloy (75Cu-24Zn-1Ca).

Figure 2 is a table showing the alloy composition and hardness of the preferred examples and comparative examples of the high-cut copper alloy according to the present invention.

Figure 3 is an optical microscope comparison picture of the cast alloy of the preferred embodiment and comparative example of a high-cut copper alloy according to the present invention.

4 is an optical microscope comparison picture of an alloy formed by hot rolling a preferred example and comparative example of a high-cut copper alloy according to the present invention.

Fig. 5 is a table comparing torques generated when drilling Example 2 (cast alloy) of a high-cut copper alloy according to the present invention and a conventional copper alloy (C3604).

Fig. 6 is a physical photograph comparing the shape of chips generated by Example 2 (cast alloy) of a high-cut copper alloy according to the present invention and a conventional lead-containing copper alloy (C3604).

7 is a graph showing a comparison of the tensile properties of the comparative example and the example of the high-cut copper alloy according to the present invention.

8 is a table summarizing FIG.

The present invention relates to a copper alloy, and more particularly, calcium and silicon (Si) are added to a copper alloy made of copper (Cu) and zinc (Zn), and additionally, cast granules such as phosphorus (P) and zirconium (Zr). The present invention relates to a high cutting copper alloy in which a small amount of fine material is added to improve cutting workability, hot and cold workability, strength and ductility.

Recently, as the use of copper has been expanded in various ways, researches on the development of copper alloys with improved workability have been actively conducted to realize various shapes.

However, copper has a high elongation, and thus, copper is easily adsorbed to the tool when the cutting tool is processed, thereby causing a problem of reduced workability. In order to solve this problem, various researches such as development of a high-cutting copper alloy having a new alloy composition have been conducted.

For example, in the early days of active research to improve the machinability of copper alloys, lead brass was prepared by adding 2.5 to 3.7 wt% of lead (Pb) to copper, and it was possible to obtain very excellent properties in terms of machinability.

However, the harmful effects of lead have been discovered in the world, leading to strong restrictions on the use of lead worldwide, and the difficulty in removing lead from copper is very difficult and the low recyclability poses a problem in terms of efficient use of finite resources. Accordingly, researches on additives that can replace lead have been conducted.

As a result, high-cut lead-free brass was developed in which bismuth (Bi) was added to copper. However, bismuth has not yet been clearly identified as harmful to the human body, and the recyclability is also low as in the case of lead, so the use of bismuth is limited in terms of material sustainability.

In the high cutting copper alloy, first, an element which forms a second phase of an intermetallic compound which is hardly dissolved in the copper alloy and is not excellent in toughness, is added. 10-2007-0009295 discloses a "free-cutting copper alloy" in which calcium is added to increase the machinability of copper.

Calcium has little solubility in copper alloys and is known to produce Cu ₅ Ca intermetallic compounds. These intermetallic compounds have very low fracture toughness, which can improve the machinability of copper alloys evenly distributed in copper alloys. You can expect

However, the machinability of the free-cut copper alloy was improved by adding calcium, but resulted in a decrease in hot and cold workability. This is because the continuity of the copper alloy matrix is inhibited by the Cu ₅ Ca phase continuously generated along the grain boundary as shown in FIG. 1, and the intermetallic compound is preferentially destroyed during processing, thereby greatly reducing the ductility of the entire alloy. .

Therefore, it is necessary to control the microstructure of the developed calcium alloy in order to improve the workability, ie ductility. Since the Cu ₅ Ca phase of the process structure is very likely to be formed in the form of a plate when solidified, the Cu ₅ Ca phase is more likely to be formed in a spherical shape than the plate shape and the size thereof may be reduced when the casting structure or particles are refined. .

In this case, the ductility can be increased by greatly improving the continuity of the copper alloy matrix.

On the other hand, the free-cutting copper alloy is mainly used as a structural part, so the strength of the structure must be maintained. In this case, the copper alloy having a high strength has the same volume of the lighter component or the same mass as the lower strength copper alloy. It is expected that the use of high-strength free-cut copper alloys can be rapidly increased as the production of large parts becomes possible.

In addition, if the production is made by a rolling method capable of mass production, it is expected that not only productivity may be increased, but also the second phase which is easily generated continuously by rolling may be discontinuously and uniformly distributed.

An object of the present invention is to add a predetermined calcium and silicon to copper and zinc, and additionally added cast granules to remove the inclusions and to control the inclusion distribution through hot rolling, as well as to improve the machinability and workability. It is to provide high cutting copper alloy as much as possible.

The high-cut copper alloy with improved strength and ductility according to the present invention for achieving the above object is copper (Cu), zinc (Zn), calcium (Ca), silicon (Si) and cast grain fine material Characterized in that configured to include.

The copper (Cu) is 57.0 to 59.4% by weight, zinc (Zn) is 40% by weight, calcium (Ca) is 0.5 to 1.0% by weight, silicon (Si) is included less than 2.0% by weight, the balance (殘部) It is characterized in that the cast granule fine fire.

The cast granulated fine material is characterized in that it comprises 20 to 100ppm phosphorus (P) and 10 to 80ppm zirconium (Zr).

It can be machined with a hot working rate of 80% or less and a cold working rate of 60% or less.

It has a hardness of 200 Hv or more.

It is characterized by having an elongation of 20% or more.

According to the present invention having such a configuration, not only the cutting property but also the ductility is improved, and the overall machinability is improved, and the strength is also greatly increased by adding silicon (Si).

Hereinafter, with reference to the accompanying Figure 2 looks at the configuration of the high-cut copper alloy (hereinafter referred to as "high-cut copper alloy") improved strength and ductility according to the present invention.

2 is a table showing the alloy composition and hardness of the preferred examples and comparative examples of the high-cut copper alloy according to the present invention.

As shown in FIG. 2, the high-cut copper alloy according to the present invention includes copper (Cu), zinc (Zn), calcium (Ca), silicon (Si), and cast grain fine materials.

The cast granulated fine material is configured to increase the cold workability of the copper alloy by preventing continuous inclusions from being formed inside the copper alloy. In addition, in the case of pure calcium (Ca), the price is high, which may cause an increase in manufacturing cost when used as an additive, but the calcium-silicon compound has an advantage of being obtained at a very low price, and additionally, an advantage of obtaining an improved copper alloy. There is this.

Various examples of the copper alloy were prepared as shown in FIG. 2 within a weight range as described above.

That is, in the copper alloys according to Examples 1 to 4, the copper (Cu), zinc (Zn), calcium (Ca) and silicon (Si) content of 58.5wt.% 40wt%, 0.5wt%, 1.0 25 to 50 ppm of phosphorus (P) and zirconium (Zr) were contained while fixed at wt%.

In addition, the copper alloy according to Example 3 and Example 4, the content of copper (Cu), zinc (Zn), calcium (Ca) and silicon (Si) 57.0wt.% 40wt%, 1.0wt%, 2.0 50 to 100 ppm of phosphorus (P) and 50 to 80 ppm of zirconium (Zr) were included as fixed at wt%.

On the other hand, in the copper alloys according to Comparative Examples 1 to 3, the content of copper (Cu), zinc (Zn), and calcium (Ca) was fixed at 20 to 100 ppm with 59.4 wt%, 40 wt%, and 0.6 wt% fixed, respectively. Phosphorus (P) and 10 to 80 ppm zirconium (Zr) were optionally included and silicon (Si) was not added.

Comparing the strength of the comparative examples and the examples prepared with the composition as described above, the hardness of the copper alloy of Comparative Examples 1 to 3 has a hardness of 111.3 (Hv) or more and 158.3 (Hv) or less as shown in FIG. As can be seen, the hardness is comparable or higher than that of general copper alloys.

As shown in FIG. 2, the copper alloys of Examples 1 to 4 have very high hardness of 196.8 (Hv) or more and 257.6 (Hv) or less.

3 shows an optical micrograph of the high-cut copper alloy cast according to the present invention. As shown in the drawings, both the comparative examples and the examples show the cast grain structure, but it can be seen that the continuous inclusions are reduced by the addition of the cast grain fine material.

This continuous reduction of inclusions can be said to be an effective casting because it can act as a factor that can increase the workability in the machining process, such as rolling in the future.

The cast high strength, high cutting copper alloy was hot rolled at 700 ° C. over 7 times with a total thickness reduction ratio of 80%, and the alloys of Comparative Examples and Examples were rolled well.

Referring to the optical micrograph of the hot-rolled high-cut copper alloy with reference to Figure 4, compared to the cast alloy, the hot-rolled alloy is found that the cast grain structure is decomposed by rolling, the second phase inclusions are distributed evenly distributed. Can be.

The even distribution of these inclusions may not only improve the machinability of the copper alloy, but also effectively improve the machinability.

Copper alloy prepared as described above can be seen through the machining process through the torque (Torque) transmitted to the drill tool as the depth is deepened during machining using the drill tool.

As shown in FIG. 5, specimens were taken from the cast alloy of the copper alloy (right picture) of Example 2 including the copper alloy (left picture) to which no cast grain fine material was added and the fine grain of the cast material. Comparing the magnitude of the torque transmitted to the drill tool when drilling with a high speed oral drill, it can be seen that the magnitude of the torque is similar.

Also, when compared to the torque during cutting of the C3604 copper alloy, which is a free cutting brass, the torque does not vary significantly, and the shape of the cut chip is similar to that of the free cutting brass (see FIG. 6).

This proves that the machinability of the copper alloy does not decrease even if the cast fine grain is added to the copper alloy.

On the other hand, as a result of evaluating cutting workability by taking specimens from hot-rolled alloys, the overall torque was reduced compared to the cast alloys. As described above, the cast grain structure was decomposed by hot rolling and the second phase inclusions were relatively reduced. This is because the cutting property is evenly distributed.

7 is a graph showing the mechanical properties of the comparative examples and examples of the copper alloy hot-rolled at 80% thickness reduction after casting according to the present invention, Figure 8 is a table summarized in FIG.

As shown in these figures, the tensile strength (TS) of the comparative example and the Example showed 407 ~ 667 MPa, the elongation was 5.5 ~ 30.1%. It can be seen that the tensile strength of these comparative examples and examples is significantly higher than the tensile strength of the commercially available C3604BE 335MPa.

In particular, in the case of the silicon-added embodiment it can be seen that the tensile strength is increased by 50% or more. On the other hand, the elongation was similar or somewhat higher in Examples 1 and 2 compared to 20% of the commercialized C3604BE, but in Examples 3 and 4, the elongation was significantly reduced.

Therefore, it can be seen that it is possible to produce a high-cut copper alloy similar to the machinability and workability while having a high strength without containing lead (Pb), which is a harmful free-cut brass.

The scope of the present invention is not limited to the above-described embodiments, and many other modifications based on the present invention will be possible to those skilled in the art within the scope of the present invention.

According to the high-cut copper alloy according to the present invention as described in detail above, a predetermined calcium (Ca) and silicon (Si) is added to copper and zinc, and additionally, cast granules such as phosphorus (P) and zirconium (Zr). A small amount was added to remove the continuous inclusions, and the distribution of the inclusions was relatively evenly controlled by hot rolling.

Accordingly, there is an advantage that the machinability, such as tensile strength and machinability, is improved while the hot rolling property is secured.

In addition, the elongation is increased, there is an advantage that can improve the cold working performance.

Claims (6)

delete delete delete 57.0 to 59.4 wt% copper (Cu), 40 wt% zinc (Zn), 0.5 to 1.0 wt% calcium (Ca), less than 2.0 wt% silicon (Si), and the balance In the high-cutting copper alloy with improved strength and ductility, including the cast granulated fine material, It can be machined with hot working rate of less than 80% and cold working rate of less than 60%, and has elongation more than 20%, The cast granulated fine material, 20 to 100ppm phosphorus (P) and 10 to 80ppm zirconium (Zr) is characterized in that the high-cut copper alloy with improved strength and ductility. 5. The high-cut copper alloy with improved strength and ductility according to claim 4 having a hardness of 200 Hv or more. 6. The high cutting copper alloy with improved strength and ductility according to claim 5, having a tensile strength of 503.7 MPa or more.

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