JPH02200750A - Aluminum alloy stock excellent in electric conductivity and its production - Google Patents

Abstract

PURPOSE:To increase electric conductivity and to improve weldability and extrudability by limiting the amount of precipitates by subjecting an Al alloy in which respective contents of Mg and Si are specified to homogenizing treatment and to cooling under respectively specified conditions and then applying hot extrusion and heat treatment to the above. CONSTITUTION:An ingot of an Al alloy having a composition consisting of 0.25-0.50% Mg, 0.25-0.50% Si, <=0.10% Fe, <=0.10%, in total, of other impurities, and the balance essentially Al is subjected to homogenizing treatment at 400-530 deg.C for 2-48hr, cooled at 10-70 deg.C/hr cooling rate, and then subjected to hot extrusion and to heat treatment, by which the amount of Mg2Si precipitates is regulated to 1.2% by area ratio. By this method, a thermal conductivity equal to or higher than that of Al of ordinary purity can be obtained. This Al alloy stock is useful as conduit line forming material for air transmission line.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an aluminum alloy material with excellent electrical conductivity and a method for manufacturing the same, and is particularly suitable for use as a conduit aerial power transmission line for power transmission. This paper relates to an aluminum alloy material and its manufacturing method.

C. Prior Art] A conduit aerial power transmission line is a new type of underground power transmission line that has recently been put into practical use. Figures 1 and 2 show cross-sectional views of the pipeline aerial power transmission line, in which aluminum alloy vibrators are used for the inner cylindrical conductor 1 and the outer cylindrical conductor 2, and the inner cylindrical conductor 1.2 is Sulfur hexafluoride-11 (SF 6 ) gas is used as an insulator in the space. A stranded wire conductor 3 is placed inside the inner cylindrical conductor 1.
is stored.

Although the material for such an aluminum alloy vibrator has not yet been determined, it is required to have good conductivity, workability, and on-site weldability. For this purpose, JIS6083 alloy, which is a typical alloy for extrusion, is used.

[Problem to be solved by the invention] The conventional JIS 8083 alloy has an electrical conductivity of 53 to 55.
(IAcs, %) was lower than 57 to 59 (IACS, %) for ordinary aluminum with a purity of 99.5%, and the power loss during power transmission was large.

Furthermore, since the JISBOfi3 alloy has poor weldability, there is a problem in that a method for joining the pipes must be devised.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an aluminum alloy material that has high electrical conductivity and excellent weldability and extrudability, and a method for producing the same.

[Means for Solving the Problem] In order to achieve the above object, the present invention provides Mg; 0.25
~0.50%, Si: 0.25~0.50%, F
e≦0.10% and other impurities in total not more than o, io%, the remainder consists essentially of Al, and Mg2Si
After homogenizing an aluminum alloy material with excellent electrical conductivity characterized by a precipitate area ratio of 1.2% or less and an alloy having the above composition at 400 to 530°C for 2 to 48 hours, lO This is a manufacturing method in which hot extrusion is performed after cooling at a cooling rate of ~70°C/hr.

The reasons for limiting the range of alloy components and manufacturing conditions in the present invention are as follows.

Mg: Mg coexists with Si to form M g 2 Si precipitates and contributes to improving the strength, but the higher the Mg concentration, the lower the electrical conductivity. Therefore, when the Mg amount is less than the lower limit, the strength as a conductor is insufficient, and when it exceeds the upper limit, the electrical conductivity decreases. Therefore, the amount of Mg is 0.2
5% to 0.5%.

St:Si coexists with Mg to form Mg2Si precipitates and contributes to improving strength, but if the amount of Si becomes too high, electrical conductivity and weldability decrease. When 5iffi is less than the lower limit, the strength as a single substance is insufficient, and when it exceeds the upper limit, the electrical conductivity becomes low. Therefore, the amount of Si is 0.2
5% to 0.5%.

Fe: Fe lowers the electrical conductivity of the aluminum alloy, so the upper limit is 0.10%.

Other impurities: Mg, Si, Cu other than Fe.

Since impurities such as Mn, Cr, Zn, and Ti lower electrical conductivity, their total amount is regulated to 0.10% or less.

Homogenization treatment conditions: Ingot homogenization treatment at 400-530℃
Good temperature range. If the homogenization temperature is below the lower limit, the Mg-5t-based product produced during casting will not fully infiltrate, resulting in low strength. The same applies when the processing time is less than the lower limit. If the homogenization temperature exceeds the upper limit, the strength will increase, but the electrical conductivity will decrease.

The same applies when the processing time exceeds the upper limit.

Cooling rate: If the cooling rate after homogenization treatment exceeds the upper limit, the strength will increase but the electrical conductivity will decrease. If the cooling rate is less than the lower limit, Mg2Si may be coarsely precipitated and the strength may be reduced. Therefore, the cooling rate is 1O~70℃/h
Let it be r.

Mg2Si precipitates: Mg2Si precipitates are necessary to ensure strength, but as the amount increases, electrical conductivity decreases. In order to obtain an electrical conductivity higher than ordinary purity aluminum (99.5%), the content was set to 1.2% or less.

(Example] The present invention will be explained below with reference to Examples and Comparative Examples.

Example 1 A 150φ ingot of an alloy having the composition shown in Table 1 was homogenized and cooled under the conditions shown in Table 1, and then extruded at 480°C into a tube with an outer diameter of 80+gs and a wall thickness of 5II 1m, and subjected to the treatment shown in Table 1. A TB material was prepared under the conditions shown in ``Conditions'', and its performance was evaluated. As the results are shown in Table 1, Examples No. 1 to 8 have good performance.

No. 9 to 10 have low strength.

No. 11.13 has high strength but low conductivity.

No. 12 had low strength and conductivity.

No. 14.15 has low conductivity, and No. 18 has low strength.

Example 2 A 150φ ingot of No. 1 alloy shown in Table 1 was extruded into a tube with an outer diameter of 601111×wall thickness of 5Il1m and heat treated under the conditions shown in Table 2. Table 2 shows its performance.

Examples No. 21 to 30 have good strength and conductivity.

Nos. 31 and 32 have low strength and conductivity.

NO43-34 have high strength but low conductivity.

No. 35 has high conductivity but low strength.

Example 3 Tests similar to those in Table 2 were conducted using alloys No., i, and 4.8 in Table 1 and changing the heat treatment conditions, and the results are shown in Table 3.

The criteria for the present invention used in the above examples were as follows.

Proof strength in tensile test: 6゜5kgf/am2 or more
Tensile strength: 11゜5 kgf/am2 or more Elongation: 15% or more Welding cracking sensitivity: 10% or less Electrical conductivity: 59% or more In addition, the welding cracking susceptibility test was conducted by welding bushbone test materials with stepwise changes in depth of cut. 5. At this time, the propagation of cracks generated from the edges was stopped by restraint relaxation, and the crack susceptibility was evaluated by the ratio of the crack length to the length of the test material. The welding conditions are welding wire"l5
-A535B alloy, W pressure 18V, electric power All 0A, welding speed 18eg+/min.

[Effects of the Invention] According to the present invention, an aluminum alloy material with high electrical conductivity and excellent weldability and extrudability is obtained, which is useful as a tube furnace forming material for pipe air power transmission. It is.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are explanatory diagrams of a conduit aerial power transmission line. 1...Inner cylindrical conductor, 2...Outer cylindrical conductor, 3...
・Twisted conductor. Patent Applicant Sumitomo Light Metal Industries Co., Ltd. Agent Patent Attorney Hide Komatsu Agent Patent Attorney Hiroshi Asahi

Claims (2)

[Claims] (1) Mg: 0.25~0.50%, Si: 0.25~
0.50%, Fe≦0.10% and other impurities in a total of 0.10% or less, the remainder substantially consists of Al, and the area ratio of Mg_2Si precipitates is 1.2% or less. An aluminum alloy material with excellent electrical conductivity. (2) Mg: 0.25~0.50%, Si: 0.25~
Homogenization of an aluminum alloy containing 0.50%, Fe≦0.10% and other impurities in a total of 0.10% or less, with the balance substantially consisting of Al at 400 to 530°C for 2 to 48 hours. After the treatment, it is cooled at a cooling rate of 10 to 70°C/hr, and then hot extruded and heat treated to reduce the area ratio of Mg_2Si precipitates to 1.2% or less. Excellent electrical conductivity. Manufacturing method of aluminum alloy material.