JPS5952223B2 - Copper alloy for aquaculture cages - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to the use of a copper alloy (Cu), which has particularly high strength and excellent corrosion resistance, and is suitable for use as wire mesh and supports for cages, as well as structural materials for marine structures. alloy).

□Currently, while the 200 nautical mile area has become established worldwide,
As fishing resources in deep-sea fishing grounds are also being depleted,
The current situation is that it has become unavoidable to seek fishery resources from coastal fishing grounds.

Since aquaculture is an effective means of securing fishery resources in such coastal fishing grounds, various attempts have been made regarding aquaculture, and are achieving great results.

By the way, in this aquaculture fishery, it is essential to use containers for raising fish and shellfish, that is, cages for raw fish, and these cages are required to have the following characteristics. .

In other words, (a) Since the raw material is used in seawater, it must have sufficient corrosion resistance against seawater.

(b) Fish cages are used to move fish from the coast to offshore as they grow, and to protect farmed fish from environmental hazards such as oil spills and red tides. Fish are moved underwater, and even when they are in the cage, they are affected by the waves, so a considerable load is placed on the cage, especially the wire mesh, and the wire mesh can be damaged, causing the fish to be cultured. etc. may escape, so raw cages, especially wire mesh, must have sufficient strength to prevent damage from these external forces.

(C) In recent years, there has been a tendency for the cages themselves to become larger, and as a result, there has been a strong demand for reducing the diameter of the wire mesh in order to reduce weight. Based on experience, it must have mechanical properties such as a tensile strength of 6.0 kg and 7 mm2 or more, and an elongation of 20% or more.

1(d) When manufacturing the wire mesh and pillars that make up the cage, raw materials must have excellent plastic flexibility, as they are subjected to hot extrusion and cold working.

(e) If seaweed or microorganisms adhere to the cages used for raw fish, especially the wire mesh, the mesh will become clogged and seawater will be blocked from flowing in, causing a lack of oxygen in the cages and causing the death of farmed fish. In particular, the wire mesh must have properties that prevent seaweed and microorganisms from adhering to it.

(f) Harmful elements that would accumulate in the bodies of farmed fish, etc. must not be leached out.

On the other hand, currently, various materials such as galvanized steel wire, steel wire, nylon wire, cupronickel wire, etc. are used and put into practical use for the wire mesh of raw cages, especially raw cages. However, the above-mentioned wire does not satisfy the characteristics required for a screen, and even the cupronickel wire, which is attracting particular attention, has problems in terms of strength, and as mentioned above, the wire is not suitable for use in extremely harsh environments. is not fully satisfactory as a wire mesh material for cages.

From the above-mentioned viewpoint, the present inventor conducted research to obtain a material that satisfies the above-mentioned characteristics required for cages for cultured bundles, especially for wire nets for live cages, and found that Mn: 5 to 30 %.

Contains Zn: 5 to 25%, Ni: Q, 2 to 20%, A1: 0.1 to 3.0%, and further contains rare earth elements: 0.01 to 0.3%, if necessary.
.

A Cu alloy with a composition consisting of Cu and unavoidable impurities (at least % by weight) has excellent corrosion resistance equivalent to or better than that of conventional cupronickel, and We have obtained the knowledge that it satisfies all the properties required for raw wire cages, especially raw wire cages, such as having higher strength than cupronickel, excellent plastic workability, and bactericidal action. It was.

This invention was made based on the above knowledge, and the present invention was made by adding Fe and Ti to the Cu alloy having the above composition for the purpose of refining the crystal grains, and adding PB and Te for the purpose of improving the machinability. , and C for the purpose of improving strength.
O and Si are added to S! for the purpose of further improving corrosion resistance.
1 and In in a total of 3% by weight, respectively, as necessary.
Even if Cu is contained within a range not exceeding 100%, the properties of the above-mentioned Cu alloy, which has the properties required for raw bamboo cages, will not be impaired in any way.

Next, the reason why the composition range of the Cu alloy of the present invention is limited as described above will be explained.

(a) Mn The Mn component lowers the melting temperature of the alloy to facilitate melting and casting, and increases the alloy strength.

However, if the content is less than 5%, the desired effect cannot be obtained, while if the content exceeds 30%, the corrosion resistance will decrease rapidly. It was set at 30%.

(b) The Zn component has the same effect as the above-mentioned Mn component, and also has the effect of improving hot extrudability, but if its content is less than 5%, the desired effect cannot be obtained;
If the content exceeds 5%, the elongation of the alloy will decrease and the cooling workability will also deteriorate, so the content was set at 5 to 25%.

(C) Although the Ni component has the effect of improving the corrosion resistance of the alloy,
If the content is less than 0.2%, the desired corrosion resistance cannot be secured, while if the content exceeds 20%, the melting point of the alloy will exceed 1000°C, and as a result, the Zn
The content was determined to be 0.2 to 20% because the evaporation becomes significant, which not only makes dissolution work difficult, but also makes it difficult to adjust the component composition, and also causes high costs.

(d) AI In addition to improving the alloy strength, the AI acid component has a molten metal deoxidizing effect, but if the content is less than 0.1%, the desired effect cannot be obtained; If it is contained in excess of %, the wire rod will not only have a marked decrease in its elasticity but also become too brittle to be used as a wire rod.
Its content was determined to be 0.1 to 3.0%.

(e) Rare earth elements Rare earth elements are included as necessary when it is necessary to further improve the corrosion resistance of the alloy, but if the content is less than 0.01%, the desired corrosion resistance improvement effect will not be achieved; If the content exceeds 0.3%, it will not only be difficult to dissolve but also cause defects to occur in the ingot, so the content was set at 0.01 to 0.3%.

Next, the Cu alloy of the present invention will be explained using examples and compared with conventional materials.

First, molten alloys each having the final component composition shown in Table 1 are prepared using an ordinary high-frequency furnace, and cast.
Next, the resulting ingot was subjected to regular hot extrusion and cold drawing to reduce the outer diameter to 3.
．． Invention alloy wire rods 1 to 23 each having a diameter of 2 mm were manufactured.

For the purpose of comparison, commercially available conventional wire rods 1 to 9 shown in Table 1, each having an outer diameter of 3.2 mmφ, were also prepared.

Next, the tensile strengths of the alloy wire rods 1 to 23 of the present invention and conventional wire rods 1 to 9 thus prepared were measured, and a corrosion resistance test was conducted by immersing them in seawater for one year.

In the corrosion resistance test, the depth of corrosion and its appearance were measured and observed.

These measurement results are also shown in Table 1.

As shown in Table 1, stainless steel wire is the best among conventional wire rods in terms of strength and corrosion resistance, but it is undesirable for use as a cage when raw because it is highly susceptible to adhesion of microorganisms.

In this respect, cupronickel wire has almost no adhesion of microorganisms or generation of wire flux, and has excellent corrosion resistance, but it has problems in terms of strength.

In addition, all other conventional wire materials have low strength, and although some exhibit excellent corrosion resistance, they all cause wire bundles and significant adhesion of microorganisms, making them difficult to use raw as cages. There's a problem.

On the other hand, the alloy wire rods of the present invention have high strength and excellent corrosion resistance, and there is almost no adhesion of microorganisms or generation of wire bundles, so they are extremely suitable for use as cages when raw. It is clear that.

As mentioned above, the Cu alloy of the present invention has excellent corrosion resistance equivalent to or better than that of cupronickel, which has been attracting attention as the most useful of conventional wire materials, and has superior corrosion resistance to conventional cupronickel in terms of strength. It has extremely high strength that far surpasses that of other metals, and has extremely excellent properties such as almost no change in its surface properties even when exposed to seawater for a long period of time.It also has excellent plastic workability and bactericidal properties. Therefore, it exhibits extremely excellent properties when used as a structural material for raw materials, especially raw materials, as well as wire mesh for raw materials, as well as other structures for ditches.

Claims (1)

[Claims] 1 Mn: 5 to 30%, Zn: 5 to 25%, Ni: 0.2 to 20%, A1: 0.1 to 3.0%, Cu and inevitable impurities: remainder, (hereinafter % by weight) is a copper alloy for aquaculture cages. 2 Mn: 5-30%, Zn: 5-25%, Ni: 0.2-20%, A1: 0.1-3.0%, Rare earth elements: 0.01-0.3%, Cu and unavoidable Impurities: Residual (more than % by weight) A copper alloy for aquaculture cages.