CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a National Stage of International Application No. PCT/KR2017/011419, filed Oct. 16, 2017 which claims priority to Korean Application No. 10-2017-0060919, filed May 17, 2017, the disclosure of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to an aluminum alloy for a cable conductor. Specifically, the present invention relates to an aluminum alloy for a cable conductor, which is excellent in both mechanical properties, such as tensile strength, at room temperature and high temperatures and elongation, and electrical conductivity, is simple to manufacture at low costs, and is eco-friendly.

BACKGROUND OF THE INVENTION

Aluminum conductor wire is lighter and cheaper than copper conductor wire and copper alloy conductor wire. In addition, aluminum has been widely used for overhead transmission lines, underground transmission lines, cables for buildings, etc., because it is easy to cast, is easy to be used in alloys with other metals, is easy to process at room temperature and high temperatures, and has excellent corrosion resistance and durability in the air.

However, pure aluminum is excellent in elongation, electrical conductivity, etc. but is insufficient in mechanical strength such as tensile strength. In particular, when used for conductors of cables in a highly vibrated environment, e.g., automobiles, planes, motors, etc., mechanical strength which is a factor for determining resistance to vibration should be improved.

Therefore, related art of improving the mechanical strength of an aluminum alloy through alloying of aluminum (Al) with an alloying element such as iron (Fe), copper (Cu), magnesium (Mg), zirconium (Zr), and beryllium (Be) has been known.

However, in the case of an existing aluminum alloy, an excessive amount of an alloying element should be added thereto to achieve desired mechanical strength and thus elongation, electrical conductivity, etc. which are in a tradeoff relation with the mechanical strength decrease greatly or should be heat treated at high treatments or for a long time for manufacture. Furthermore, environmental problems may occur and manufacture costs may increase due to the addition of beryllium (Be) which is an environmentally regulated material.

In addition, when a small amount of an alloying element is added to the aluminum alloy to avoid a large decrease in elongation, electrical conductivity, etc., the mechanical strength of the aluminum alloy is insufficiently improved or a grain refinement process is additionally required to improve the mechanical strength of the aluminum alloy, thereby complicating a manufacturing process.

Under this circumstance, in the current mainstream cable industry, research is being actively conducted on improvement of both mechanical strength, such as tensile strength, of aluminum alloys and elongation, electrical conductivity, etc. which are in a tradeoff relation with the mechanical strength so as to replace copper conductor wire and copper alloy conductor wire with aluminum alloy conductor wire. However, there are many difficulties in technological progress because an optimal combination of alloying elements and process conditions for aluminum alloys have yet to be established.

Therefore, there is an urgent need for an aluminum alloy for cable conductors, which is excellent both in mechanical properties, such as tensile strength and elongation, at room temperature and high temperatures, and electrical conductivity, is simple to manufacture at low costs, and is eco-friendly.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to providing an aluminum alloy for a cable conductor, which is excellent in both mechanical properties, such as tensile strength and elongation, at room temperature and high temperature and electrical conductivity.

The present invention is also directed to providing an aluminum alloy for a cable conductor, which is simple to manufacture at low costs and is eco-friendly.

According to an aspect of the present invention, provided is an aluminum alloy for a cable conductor, comprising iron (Fe), copper (Cu), boron (B) and titanium (Ti), wherein a particle diameter growth rate defined by the following Equation 1 is 30 to 70%:
particle diameter growth rate(%)=(a−b)/b*100,   [Equation 1]

wherein a represents an average particle diameter of crystal grains measured after heat treating the aluminum alloy at 600° C. for 1 hour, and

b represents an average particle diameter of crystal grains measured after heat treating the aluminum alloy at 400° C. for 1 hour.

According to another aspect of the present invention, provided is the aluminum alloy, wherein a wire rod of the aluminum alloy drawn to a diameter of 0.4 mm has tensile strength of 140 MPa or more, elongation of 15% or more, and electrical conductivity of 59% IACS or more.

According to other aspect of the present invention, provided is the aluminum alloy, further comprising at least one intermetallic compound selected from the group consisting of an Al-Fe intermetallic compound, an Al-Cu intermetallic compound and an Al-Ti intermetallic compound.

According to other aspect of the present invention, provided is the aluminum alloy, wherein the iron (Fe) is contained in an amount of 0.3 to 0.6 wt %, the copper (Cu) is contained in an amount of 0.3 to 0.5 wt %, the boron (B) is contained in an amount of 0.001 to 0.01 wt %, and the titanium (Ti) is contained in an amount of 0.01 to 0.03 wt %, based on total weight of the aluminum alloy.

According to other aspect of the present invention, provided is the aluminum alloy, wherein impurities selected from the group consisting of vanadium (V), chromium (Cr) and nickel (Ni) are contained in an amount of 0.1 wt % or less, based on total weight of the aluminum alloy.

According to other aspect of the present invention, provided is the aluminum alloy, wherein each of vanadium (V), chromium (Cr) and nickel (Ni) is contained in an amount of 0.01 wt % or less, based on the total weight of the aluminum alloy.

According to other aspect of the present invention, provided is the aluminum alloy, wherein tensile strength when the aluminum alloy is heat-treated at 310° C. for six hours after being drawn is 90% or more of tensile strength before the heat treatment is performed.

According to other aspect of the present invention, provided is a cable conductor manufactured by preparing a rod by continuous casting and rolling by adjusting pouring temperature of the aluminum alloy to 720 to 780° C., drawing the rod to a diameter of 0.4 mm, and performing heat treatment thereon at 310° C. for six hours.

An aluminum alloy for a cable conductor according to the present invention is excellent in improving all tensile strength at room temperature and high temperatures and elongation and electrical conductivity, etc., which are in a tradeoff relation with the tensile strength, through selection of specific alloying elements, a mixing ratio, and a particle diameter growth rate precisely controlled when heating.

In addition, the aluminum alloy for a cable conductor according to the present invention is simple to manufacture at low costs because an additional high-temperature and long-time heat treatment and an additional grain refinement process are not needed, and is eco-friendly because environmentally regulated materials can be excluded as alloying elements.

