JP6473465B2 - Aluminum alloy conductor wire and method for manufacturing the same - Google Patents

Description

  The present invention relates to an aluminum alloy conductor electric wire and a method for producing the same, and more specifically, it is excellent in mechanical strength such as tensile strength, and is excellent in elongation that is in a trade-off relationship with the strength. In addition, the present invention relates to an aluminum alloy conductor wire excellent in electrical conductivity and a method for manufacturing the same.

  Aluminum conductor wires are lighter and cheaper than copper conductor wires and copper alloy conductor wires, are easy to cast, and are easily alloyed with other metals. It is widely used as a conductor for processed transmission lines, underground transmission lines, building cables, etc. because it is easy to process and has excellent corrosion resistance and durability in the atmosphere.

  However, pure aluminum conductor wires have excellent properties such as elongation and electrical conductivity, but have insufficient mechanical strength such as tensile strength. Especially, cables used in automobiles, aircraft, prime movers, etc. When it is applied as a conductor of a cable used in such severe vibration environment, it is necessary to improve the mechanical strength that determines the resistance to vibration.

  Therefore, conventionally, the mechanical strength of aluminum alloy conductor wires is improved through the alloy of aluminum (Al) and alloy elements such as iron (Fe), copper (Cu), magnesium (Mg), zirconium (Zr), and beryllium (Be). Improvement techniques have been proposed.

  However, since a conventional aluminum alloy electric wire requires an excessive amount of alloying elements to achieve the intended mechanical strength, the elongation rate and electrical conductivity, etc., which are in contradiction to the mechanical strength, are not good. There are problems such as a significant decrease in temperature, a high heat treatment temperature required for production, a long heat treatment, and the addition of beryllium (Be), which is an environmentally regulated substance. There was a problem that the production unit price increased.

  In addition, when a small amount of alloy element is added to avoid a significant decrease in the elongation rate, electrical conductivity, etc. of the aluminum alloy conductor wire, the mechanical strength of the aluminum alloy conductor wire is insufficiently improved, In order to improve the mechanical strength of the aluminum alloy conductor wire, there is a problem that the manufacturing process becomes complicated, such as the need for a crystal grain refinement process.

  Under such circumstances, in the current cable industry, in order to replace copper conductor wires and copper alloy conductor wires with aluminum alloy conductor wires, the mechanical strength such as tensile strength and the elongation rate, which has a contradictory relationship, Although active research has been conducted to improve the electrical conductivity at the same time, the optimal alloy element combinations and process conditions for aluminum alloy conductor wires have not been established. The tensile strength increases as the wire diameter decreases, but the elongation and electrical conductivity tend to decrease. Therefore, in the case of a thin wire conductor wire with a diameter of 0.15 to 0.5 mm, the optimum combination of alloy elements Is extremely difficult to find, and involves great difficulty in technological progress.

   The present invention relates to an aluminum alloy conductor electric wire, which is excellent in mechanical strength such as tensile strength, elongation, and electrical conductivity at the same time, even when the diameter is small. The purpose is to provide.

  Another object of the present invention is to provide an aluminum alloy conductor wire that is environmentally friendly and can reduce production costs.

  Furthermore, it is a further object of the present invention to provide a method for manufacturing the aluminum alloy conductor wire, which has a simple manufacturing process, thereby reducing manufacturing costs.

  In order to achieve the above object, the present invention provides iron (Fe) 0.3 to 0.6% by weight, copper (Cu) 0.3 to 0.5% by weight, boron (B) 0.001 to 0.01%. The remaining balance is formed from an aluminum alloy composition comprising aluminum (Al) and unavoidable impurities, including 0.01% by weight and titanium (Ti) 0.01% to 0.03% by weight. An aluminum alloy conductor wire having an average distance between precipitates of 2 to 15 μm and an average diameter of 0.15 to 0.5 mm, which is an average of distances between precipitates distributed within a unit radius (50 μm). provide.

  Here, the boron (B) and the titanium (Ti) are present as an Al—Ti—B intermetallic compound, and provide an aluminum alloy conductor wire.

The precipitate may be selected from the group consisting of an Al—Fe intermetallic compound, an Al—Cu intermetallic compound, and an Al—Ti—B intermetallic compound.

Also provided is an aluminum alloy conductor electric wire characterized in that the average grain size of crystal grains is 40 μm or less.

  And the aluminum alloy conductor electric wire characterized by tensile strength of 140 MPa or more, elongation of 15% or more, and electrical conductivity of 59% IACS or more is provided.

Moreover, the inevitable impurities are vanadium (V), a chromium (Cr) and nickel (Ni), aluminum alloy conductor wires, characterized in that each of the contents of inevitable impurities is not more than 0.01 wt% provide.

  Meanwhile, a step of producing an aluminum alloy composition containing iron (Fe), copper (Cu), etc., and the remaining remaining amount of aluminum and inevitable impurities, and Al—Ti immediately before the casting of the aluminum alloy composition A step of adding a B alloy, a step of producing an aluminum alloy wire by continuous casting and rolling of the aluminum alloy composition, a step of drawing the aluminum alloy wire, and heat treating the aluminum alloy wire that has undergone the wire drawing step A method for manufacturing an aluminum alloy conductor wire.

Here, prior to the addition of the Al-Ti-B alloy, and said containing Mukoto the step of filtering the de-gasification and debris of the aluminum alloy composition, a production method of an aluminum alloy conductor wires To do.

  Moreover, the temperature of the aluminum alloy composition continuously cast and rolled is 730 to 900 ° C., and the method for producing an aluminum alloy conductor wire is provided.

  Furthermore, the heat treatment is carried out at 260 to 360 ° C. for 2 to 12 hours, and the average grain size of the crystal grains after the heat treatment is 50 μm or less.

  The aluminum alloy conductor wire according to the present invention has a mechanical strength of an aluminum alloy conductor wire even when the diameter is small, and an elongation ratio that is incompatible with this, even when the diameter is small, by selecting a specific alloy element and precisely controlling the compounding ratio. There is an excellent effect that electric conductivity and the like can be improved at the same time.

  Since the aluminum alloy conductor wire according to the present invention does not use an alloy element that induces environmental problems, it is environmentally friendly and has an excellent effect of reducing production cost because it does not contain an excessive amount of alloy elements.

  The method for producing an aluminum alloy conductor wire according to the present invention does not require a separate grain refinement process, so the production process is simple, thereby reducing the production cost and controlling the precise process conditions. There is an excellent effect that the characteristics of the aluminum alloy conductor wire manufactured by the method can be improved uniformly.

It is a flowchart of the manufacturing process of the aluminum alloy conductor wire which concerns on this invention. It is the figure which showed the distance between deposits in the SEM photograph of the aluminum alloy conductor wire of Example 1 which concerns on this invention, and the SEM photograph of the aluminum alloy conductor wire of the comparative example 5. And SEM photograph of the aluminum alloy conductor wires according to the first embodiment of the present invention and shows a SEM photograph of the aluminum alloy conductor wires of Comparative Example 5.

  Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the embodiments described herein, and can be embodied in other forms. Rather, the embodiments presented herein are provided so that the content disclosed may be thorough and complete so as to fully convey the spirit of the invention to those skilled in the art.

  An aluminum alloy composition for forming an aluminum alloy conductor wire according to the present invention contains aluminum (Al) as a main component, and iron (Fe), copper (Cu), boron (B), and titanium (Ti) as alloy elements. Is further contained. The aluminum alloy conductor electric wire is a thin wire having an average diameter of 0.15 to 0.5 mm, and the aluminum alloy conductor electric wire having such a thin wire has a mechanical strength such as tensile strength and a contradictory relationship therewith. Although it is extremely difficult to improve the elongation rate and electrical conductivity at the same time, the crystal is controlled by controlling the optimum alloying ratio of the alloy elements described below and the distance between the precipitates forming the crystal grains. This can be achieved through grain refinement.

  Iron (Fe) as the alloy element exists as an Al—Fe intermetallic compound in the matrix. In particular, the Al—Fe intermetallic compound improves mechanical strength such as tensile strength by suppressing the growth of crystal grains because most of the Al—Fe intermetallic compound is precipitated in the heat treatment stage during the manufacturing process of the aluminum alloy conductor wire. Will work.

  Here, the iron (Fe) content may be 0.3 to 0.6% by weight based on the total weight of the aluminum alloy composition. When the iron (Fe) content is less than 0.3% by weight, the mechanical strength of the aluminum alloy conductor wire is insufficiently improved. On the other hand, when it exceeds 0.6% by weight, Al— When the Fe intermetallic compound becomes coarse, the extrudability of the aluminum alloy composition is lowered, and the elongation rate and electrical conductivity of the aluminum alloy conductor wire may be greatly reduced.

  In addition, copper (Cu) as an alloy element is dissolved in aluminum (Al) to increase the corrosion potential of the aluminum alloy and improve the corrosion resistance of the aluminum alloy. -Cu exists as an intermetallic compound, and precipitates at the heat treatment stage to suppress the growth of crystal grains, thereby improving the mechanical strength such as tensile strength.

  Here, the copper (Cu) content may be 0.3 to 0.5% by weight based on the total content of the aluminum alloy composition. When the content of copper (Cu) is less than 0.3% by weight, the degree to which the mechanical strength of the aluminum alloy conductor wire is improved is insufficient. If the compound becomes coarse, the extrudability of the aluminum alloy composition is lowered, and the elongation rate and electrical conductivity of the aluminum alloy conductor wire may be greatly reduced.

  Boron (B) as the alloy element promotes the precipitation of intermetallic compounds at the heat treatment stage in the manufacturing process of the aluminum alloy conductor wire, thereby suppressing the coarsening of the crystal grains. It will increase the strength and suppress the decrease in electrical conductivity.

  Here, the boron (B) content may be 0.001 to 0.01% by weight based on the total weight of the aluminum alloy composition. When the content of boron (B) is less than 0.001% by weight, the degree to which the mechanical strength of the aluminum alloy conductor wire is improved is insufficient. There is a possibility that the electrical conductivity of the aluminum alloy conductor wire is greatly reduced by generating a compound.

  Titanium (Ti) as the alloy element has a melting point of 1800 ° C., which is higher than the melting point of 1540 ° C. of iron (Fe), which is another alloy element, and 1084.5 ° C. of copper (Cu). -B alloy rods are added in the form of rods and are present uniformly as Al-Ti precipitates in the aluminum alloy, thereby further increasing the average distance between precipitates that determine the crystal size of the aluminum alloy. As a result, the strength of the aluminum alloy conductor wire is further improved by refining the crystal grains.

  Deposits at an average distance between the precipitates include not only Al—Ti intermetallic compounds but also Al—Fe intermetallic compounds, Al—Cu intermetallic compounds, and the like, and are reduced by the addition of titanium (Ti). The average distance between the precipitates, that is, the average distance between the precipitates distributed within the unit radius (50 μm) based on an arbitrary precipitate is preferably 2 to 15 μm, more preferably 2 to 5.5 μm. In this way, by reducing the average distance between the precipitates, the precipitates can act as a barrier and suppress the growth of crystal grains. That is, since titanium (Ti) acts as a mechanism for grain refinement to reduce the average distance between precipitates, the average grain size of the grains can be controlled to about 50 μm or less, preferably about 10 to 40 μm. Excellent effect is achieved.

  In addition, since the aluminum alloy to which titanium (Ti) is added can be made finer by the Al-Ti intermetallic compound as described above, it can be used at a higher temperature to improve the elongation rate of the aluminum alloy, or Even when heat treatment is carried out for a longer time, the degree of decrease in tensile strength is much lower than that of the aluminum alloy to which titanium (Ti) is not added, so that titanium (Ti) is not added and the same tensile strength is exhibited. The elongation rate greatly improved as compared with the elongation rate of the aluminum alloy can be shown.

  Here, the titanium (Ti) content may be 0.01 to 0.03% by weight based on the total weight of the aluminum alloy composition. When the content of titanium (Ti) is less than 0.01% by weight, the effect of refining crystal grains of the aluminum alloy conductor wire is difficult to be exhibited. On the other hand, when the content exceeds 0.03% by weight, a large amount of impurities are contained in the aluminum alloy. Is added to produce a coarse intermetallic compound, and the extrudability of the aluminum alloy composition and the tensile strength and electrical conductivity of the aluminum alloy conductor wire may be reduced.

In addition to aluminum (Al) as a main component and iron (Fe), copper (Cu), boron (B), and titanium (Ti) as an alloy element, the aluminum alloy composition is inevitably added in the manufacturing process. as impurities, for example, vanadium (V), made and Nde containing chromium (Cr) and nickel (Ni), each content of the inevitable impurities state, and are for example 0.01 wt% or less, the unavoidable impurities the total content of, for example, 0.1 wt% or less.

  The aluminum alloy conductor wire manufactured from the aluminum alloy composition has a uniform distribution of fine precipitates from iron (Fe), copper (Cu) and titanium (Ti) added as alloy elements, that is, precipitates. The tensile strength of 140 Mpa or more is exhibited through the refinement of crystal grains by reducing the distance between them and through further refinement of crystal grains by promoting precipitation of intermetallic compounds such as Al-Fe and Al-Cu by boron (B), Through miniaturization of crystal grains, long-term heat treatment can be performed at a high temperature while minimizing the decrease in tensile strength, so that the elongation rate can be improved to 15% or more and the electrical conductivity to 59% IACS or more at the same time. An excellent effect that can be achieved.

  FIG. 1 is a flowchart of a manufacturing process of an aluminum alloy conductor wire according to the present invention.

  As shown in FIG. 1, the method of manufacturing an aluminum alloy conductor wire according to the present invention can include the following steps a) to e).

That is, a) an aluminum alloy composition containing 0.3 to 0.6% by weight of iron (Fe) and 0.3 to 0.5% by weight of copper (Cu), with the remaining remaining portion being made of aluminum and inevitable impurities Producing a product (molten metal) (S110);
b) Al—Ti—B alloy is added immediately before casting the aluminum alloy composition to further add 0.001 to 0.01% by weight of boron (B) and 0.01 to 0.03% by weight of titanium (Ti). Producing an aluminum alloy composition comprising (S120);
c) producing an aluminum alloy wire by continuous casting and rolling of the aluminum alloy composition (S130);
d) drawing the aluminum alloy wire (S140);
e) the drawing process the aluminum alloy wire which has undergone a heat treatment 2-12 hours at a temperature range of two hundred and sixty to three hundred and sixty ° C. Step (S150) and; the including.

In particular, the production method of the aluminum alloy conductor wire according to the present invention, a) a step (S110) Thereafter, further including the degassing and filtration step of the foreign matter of the aluminum alloy composition. Here, the degassing and foreign matter filtering steps are preferably performed between a) step (S110) and b) step (S120). b) When the degassing and foreign matter filtering steps are performed after step (S120), there is a risk that the Al—Ti intermetallic compound may leak together with the gas.

  As described above, the Al-Ti-B alloy precipitates added in step b) are uniformly distributed in the matrix, thereby reducing the distance between the precipitates that determine the size of the crystal grains. As a result, the mechanical strength such as the tensile strength of the aluminum alloy can be improved by refining the crystal grains.

  Thus, the method for producing an aluminum alloy conductor wire according to the present invention does not require a separate crystal grain refinement step, and thus the production process is simple, thereby reducing the production cost.

  Meanwhile, in step c) (S130), the temperature of the aluminum alloy composition applied to the continuous casting and rolling is preferably 730 to 900 ° C. The reason why the injection temperature of the composition applied to the continuous casting and rolling is limited as described above is to obtain a solid solution that is an intermetallic compound, that is, a casting having a dense microstructure.

  Here, when the injection temperature of the aluminum alloy composition exceeds 900 ° C., there is a problem that the microstructure of the casting becomes coarse. On the other hand, when the casting temperature is less than 730 ° C., the mold space is insufficient due to insufficient fluidity of the composition. There is a risk of a miss run phenomenon that cannot be filled precisely. Here, the continuous casting and rolling method may be replaced with a continuous casting method.

  The aluminum alloy wire produced in step c) is most preferably cast with a diameter of about 10 mm so as to be usefully applied to an automobile cable. Depending on the application, the diameter of the cast aluminum alloy wire may be appropriately selected by a normal engineer.

  In the wire drawing process which is the step d) (S140), the cast aluminum alloy wire is processed to reduce the cross section, thereby producing an alloy wire of a predetermined standard. For example, the step d) (S140) includes the step of thick drawing of the aluminum alloy wire produced in step c) (S130) into a wire having an average diameter of about 2 mm, and an average diameter of about 0.15 to 0. A thin wire drawing step for forming a 5 mm wire can be included.

  The aluminum alloy wire drawn in step d) step (S140) is heat-treated by a heat treatment step e) in step (S150). In the aluminum alloy wire, after the internal stress of the alloy is increased by the heat treatment, the elongation rate is improved by recovery by releasing the stress. However, if the heat treatment temperature is excessively high or the heat treatment time is excessively delayed, the tensile strength may be greatly damaged by the coarsening of the crystal grains. Therefore, when the elongation rate of the aluminum alloy wire is maximized by the heat treatment and the tensile strength is not greatly damaged, that is, when the average grain size of the crystal grains is maintained below about 50 μm, the heat treatment may be interrupted. It is the most efficient.

  E) In the heat treatment process of step (S150), the average distance between the precipitates is 2 to 15 μm, that is, the average grain size of the crystal grains is maintained at about 50 μm or less, and the elongation rate is maximized. The heat treatment temperature may be about 260-360 ° C., and the heat treatment time may be about 2-12 hours. Within the range that satisfies the heat treatment process conditions, the heat treatment time is increased as the heat treatment temperature is lowered, while the heat treatment time is shortened as the heat treatment temperature is increased, thereby minimizing the degree of decrease in tensile strength due to heat treatment, In addition, the improvement in elongation can be maximized.

1. Production Example An aluminum alloy wire containing an alloy component as shown in Table 1 below and the remainder being aluminum (Al) and inevitable impurities is produced, and a wire drawing process and a heat treatment process (310 ° C., 6 hours) The strand test piece by an Example and each comparative example was manufactured. The unit of content of the alloy components shown in Table 1 below is% by weight.

2. Evaluation of physical properties 1) Evaluation of tensile strength and elongation rate The tensile strength and elongation rate of each aluminum alloy wire test piece according to Examples or Comparative Examples were tested using a gripping device for wire according to the standard of ASTM B557. After measuring the force required to be pulled at a speed of 1 mm / s with both ends of the piece fixed, calculate the tensile strength using the offset method. The elongation percentage is calculated from the length of the test piece, and the result is as shown in Table 1 below.

2) Evaluation of electrical conductivity The electrical conductivity of each aluminum alloy wire test piece according to the example or the comparative example was calculated by measuring the electrical resistance by the Kelvin Double Bridge method according to the standard of ASTM B193.

  As shown in Table 1, the aluminum alloy strand test pieces of Examples 1 to 10 according to the present invention have an average distance between precipitates according to an optimum combination of alloy elements, a minimum content of alloy elements and an optimum blending ratio. By reducing the crystal grain size, the tensile strength is reduced to 140 MPa or more by minimizing the decrease in tensile strength even though the elongation is improved to 15% or more by heat treatment. It was confirmed that the electrical conductivity could be maintained at 59% IACS or higher by minimizing the alloy element content.

  On the other hand, in the test pieces of Comparative Examples 1 and 3, an extremely small amount of an iron (Fe) or copper (Cu) alloy element that improves the tensile strength of the aluminum alloy is added, and the degree to which the tensile strength is improved in the aluminum alloy is slight. On the other hand, in the test pieces of Comparative Examples 2 and 4, the iron (Fe) or copper (Cu) alloy element was added in an excessive amount, and the electrical conductivity in the aluminum alloy was standard. It was confirmed that the value dropped below a certain 59% IACS.

  In addition, the test piece of Comparative Example 5 is used for the refinement of crystal grains despite the addition of appropriate amounts of iron (Fe) and copper (Cu) alloy elements that improve the tensile strength of the aluminum alloy. Titanium (Ti) and boron (B) are not added, and the distance between the precipitates increases, thereby coarsening the crystal grains, resulting in a significant decrease in tensile strength during heat treatment to improve elongation. On the other hand, in the test piece of Comparative Example 6, titanium (Ti) and boron (B) were excessively added, and rather a coarse intermetallic compound was formed, and thereby the tensile strength and electrical conductivity were increased. It was confirmed that it was greatly reduced.

  In addition, the specimens of Comparative Examples 7 and 9 have excellent tensile strength because the diameter of the wire is excessively small, but the elongation rate, which is in a contradictory relationship with this, and the electrical conductivity greatly decreased, The specimens of Comparative Examples 8 and 10 were confirmed to have a large drop in tensile strength although the elongation and electrical conductivity were excellent because the wire diameter was excessively large.

  Incidentally, FIGS. 2 and 3 are comparative photographs of a scanning electron microscope (SEM) showing the distance between precipitates and the degree of crystal grain refinement in Example 1 and Comparative Example 5 depending on whether or not titanium (Ti) is added. It is.

  2 and 3, the aluminum alloy conductor wire according to the present invention reduces the distance between precipitates that determine the size of crystal grains by adding titanium (Ti). By inducing grain refinement, it is possible to minimize the degree to which the tensile strength decreases during heat treatment to improve the elongation of aluminum alloy wire, resulting in a contradictory relationship with the tensile strength. It has an outstanding effect of unpredictability that improves the growth rate at the same time.

  In addition, by reducing the grain size, sufficient tensile strength can be achieved even if only a small amount of iron (Fe) and copper (Cu) is added to the alloy elements. This produces an excellent effect of minimizing the decrease in electrical conductivity.

Although the foregoing has been a description of the preferred embodiments of the invention, those skilled in the art will recognize that the invention may be practiced in various ways without departing from the spirit and scope of the invention as defined in the claims. It should be possible to implement with modifications or variations. Therefore, if the modified implementation basically includes the constituent elements of the claims of the present invention, it should be determined that all are included in the technical scope of the present invention.

Claims (4)

Iron (Fe) 0.3-0.6 wt%, Copper (Cu) 0.3-0.5 wt%, Boron (B) 0.001-0.01 wt%, and Titanium (Ti) 0.01- 0.03% by weight, and the remaining balance is formed from an aluminum alloy composition comprising aluminum (Al) and inevitable impurities
Distance between precipitates distributed within a unit radius of 50 μm based on an arbitrary precipitate selected from the group consisting of Al—Fe intermetallic compounds, Al—Cu intermetallic compounds, and Al—Ti—B intermetallic compounds The average distance between precipitates is 2 to 15 μm, the average diameter is 0.15 to 0.5 mm, the average grain size of crystal grains is 40 μm or less, the tensile strength is 140 Mpa or more, and the elongation is Is an aluminum alloy conductor electric wire having an electrical conductivity of 59% IACS or more.   The aluminum alloy conductor wire according to claim 1, wherein the boron (B) and the titanium (Ti) are present as an Al-Ti-B intermetallic compound. The unavoidable impurities are vanadium (V), chromium (Cr) and a nickel (Ni), each unavoidable impurity content according to claim 1 or 2, wherein the at most 0.01 wt% Aluminum alloy conductor wire. Iron (Fe) 0.3-0.6 wt%, Copper (Cu) 0.3-0.5 wt%, Boron (B) 0.001-0.01 wt%, and Titanium (Ti) 0.01- Producing an aluminum alloy composition comprising 0.03% by weight, the remaining balance being aluminum and inevitable impurities;
Adding an Al-Ti-B alloy immediately before casting the aluminum alloy composition;
Performing the degassing and foreign matter filtration of the aluminum alloy composition before adding the Al-Ti-B alloy;
Producing an aluminum alloy wire by continuous casting and rolling of the aluminum alloy composition;
Drawing the aluminum alloy wire;
Heat treating the aluminum alloy wire that has undergone the wire drawing step,
The temperature of the aluminum alloy composition continuously cast and rolled is 730 to 900 ° C.,
The method for producing an aluminum alloy conductor wire according to claim 1 or 2, wherein the heat treatment is performed at 260 to 360 ° C for 2 to 12 hours, and the average grain size of the crystal grains after the heat treatment is 40 µm or less.