JP2582073B2 - Method for producing high-strength heat-resistant aluminum alloy for electric conduction - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a high-strength heat-resistant aluminum alloy for electric conduction, and more particularly to a method for producing an aluminum alloy for electric conduction excellent in strength, electric conductivity, heat resistance and toughness. Things.

The high-strength heat-resistant aluminum alloy for electric conductivity manufactured according to the present invention is used for, for example, high-strength heat-resistant ACSR, high-strength steel core high-strength heat-resistant ACSR, aluminum-coated steel core high-strength heat-resistant ACSR, high-strength heat-resistant aluminum alloy busbar, etc. It is a conductive aluminum alloy product that has both strength and heat resistance.

(Prior art and problems) In recent years, for example, in order to increase the transmission capacity and improve the reliability of the power system by operating one circuit in the event of an accident during two-circuit operation, a heat-resistant steel core aluminum alloy stranded wire (hereinafter referred to as TACSR) ) Is used.

When such TACSR is further used for transmission lines of long diameter such as overhead ground wire and crossing the strait, for example, heat resistant steel core aluminum stranded wire of long diameter (hereinafter referred to as KTACSR), high strength aluminum alloy A high-strength heat-resistant aluminum alloy wire for electric conduction, which has both tensile strength and heat resistance of a heat-resistant aluminum alloy, is required. Conventionally, work hardening type aluminum alloys have been used for such aluminum alloy wires with improved strength by cold working. However, depending on the manufacturing method, desired strength, elongation, electrical conductivity, heat resistance, toughness, etc. Therefore, a more stable alloy composition manufacturing method has been desired.

(Means for Solving the Problems) The present invention has been made to solve the above problems,
Zr: 0.25-0.7%, Si: 0.10-0.4%, Fe: 0.10-1.0%, C
u: 0.10 to 0.40% after melting the remainder usual impurities and alloy comprising _{Al, T 1 = 300 × Zr} % + 650 continuous casting from T ₁ ° C. or more casting temperature at 5 ° C. / Sec or more cooling rate represented by Then, hot rolling is started at a temperature of T ₂ ℃ or more represented by T ₂ = 400 × Zr% + 350, and processing is performed while cooling at a cooling rate of 10 ° C./Sec or more. After winding and aging at 300-450 ° C for 10-200 hours, the area reduction rate is 6
A method for producing a high-strength heat-resistant aluminum alloy for electric conduction, characterized by performing cold working of 0% or more.

(Operation and Effect) In the present invention, Zr in the aluminum alloy is dissolved in the aluminum during continuous casting and rolling, but is finely precipitated and dispersed by a subsequent heat treatment to improve heat resistance and strength. Set the Zr amount to 0.
It is specified as 25 to 0.7% because if it is less than 0.25%, the amount of precipitation is small and there is no effect on the improvement of heat resistance and strength. If it exceeds 0.7%, coarse particles will be formed in the molten metal stage unless the temperature of the molten metal is significantly increased. As a result, not only do not form fine dispersed particles due to aging but also heat resistance and strength are lowered. This is because the soundness of aluminum is impaired and production is difficult from the viewpoint of industrial production of aluminum.

In the present invention, the content of Si 0.10 to 0.40% is defined as Al-Zr
It is added in order to promote the aging characteristics of the base alloy and improve the strength and heat resistance. If it is less than 0.10%, the effect is extremely small, and if it exceeds 0.40%, cracks occur during casting, It becomes difficult, and if 0.20% or more is added, the aging characteristics are significantly improved. Fe 0.10 to 1.0% is added to improve strength, elongation and heat resistance. If it is less than 0.10%, the effect is small, and if it exceeds 1.0%, the effect is saturated and the conductivity is lowered. It is. Cu0.
Adding 10 to 0.40% is to improve the strength and heat resistance. If it is less than 0.10%, there is no effect. If it exceeds 0.40%, not only the effect is saturated, but also the conductivity and corrosion resistance decrease. It is.

In the present invention, the casting temperature is represented by T ₁ = 300 × Zr% + 650. The reason that the cooling rate at the time of casting at T ₁ ° C or higher is 5 ° C / sec or more is specified because Zr is solid-dissolved without crystallizing in the molten metal stage, and aging in the subsequent process causes Is an indispensable condition for improving strength and heat resistance. Casting temperature is less than T ₁ ° C or cooling rate during casting is 5 ° C / sec.
Below, the added Zr crystallizes or precipitates during casting,
Strength and heat resistance deteriorate.

The hot working start temperature is represented by T ₂ = 400 × Zr + 350.
Here, the reason that the temperature is defined as T ₂ ° C or more is to increase the amount of Zr dissolved in Al matrix, and when the temperature is lower than T ₂ ° C, the amount of solid solution Zr is small, and the amount of increase in strength in the subsequent thermomechanical treatment step And heat resistance deteriorates.

The cooling rate at the time of hot working is specified as 10 ° C / sec or more, which is a necessary condition for finely depositing Zr by aging in a post-process, and suppressing the precipitation of Zr at the time of hot working, In addition, it is effective to introduce dislocations. 10 ° C / s
If it is less than ec, Zr is coarsely precipitated during hot working, dislocation is little introduced, and strength and heat resistance are deteriorated. The area reduction rate in hot working is preferably 90% or more, and if it is less than 90%, toughness deteriorates.

The reason why the winding temperature is specified to be 150 ° C or lower is that if the temperature exceeds 150 ° C, a temperature difference occurs between the inside of the coil and the coil surface, and the inside of the coil becomes too high, causing variations in characteristics and product stability. Is missing.

The reason that the aging is performed at a temperature of 300 to 450 ° C. for 10 to 200 hours is to precipitate and disperse Zr finely by this aging and to improve the strength and heat resistance. The precipitation amount is small, the effect of improving the strength and heat resistance is small, and the precipitation particles are coarse when exceeding 450 ° C. and 200 hours.
Strength and heat resistance deteriorate. The reason why the cold working with a reduction in area of 60% or more is performed thereafter is to secure a desired strength, and a desired strength cannot be obtained if the reduction in area is less than 60%.

As impurities in the aluminum alloy in the present invention, Mn, T
Even if i and V are included, there is no problem, for example, Mn: 0.
001-0.003%, Ti + V: 0.001-0.003%.

Furthermore, in order to refine the structure, 0.005 to 0.1% of Ti may be added. However, B needs to be 0.002% or less from the viewpoint of heat resistance.

Further, in order to improve the conductivity, Be: 0.0005 to 0.1% can be added.

(Example) An alloy having a composition shown in Table 1 was prepared by adding Cu having a cross-sectional area of 3600 mm ² to Cu.
Casting and rolling were performed under the conditions shown in Table 1 by using a continuous cast material and a hot-rolled material constituted by an alloy rotary mold and a steel belt, to obtain a rough drawn wire of 9.5 mmφ. These rough drawn wires were aged under the conditions shown in Table 1 and then cold worked at a reduction in area of 82% to obtain a wire.

The tensile strength, elongation, electrical conductivity and heat resistance of the obtained aluminum alloy wire are as shown in Table 1. The heat resistance was determined by measuring the tensile strength at room temperature after heating at 230 ° C. for 1 hour, and expressed as a percentage of the tensile strength of the sample before heating.

From Table 1, it can be seen that No. 1 to No. 11 according to the present invention are all superior in tensile strength, elongation, electrical conductivity and overall performance of heat resistance as compared with Comparative Examples.

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-5683 (JP, A) JP-A-61-2732 (JP, A) JP-B-60-7703 (JP, B2) JP-B-61 28025 (JP, B2)

Claims (1)

(57) [Claims] (1) Zr: 0.25-0.7%, Si: 0.10-0.4%, Fe: 0.1
0~1.0%, Cu: 0.10~0.40% the remainder usual impurities and alloy comprising _{Al, T 1 = 300 × Zr} % + 650 cooling rate of 5 ° C. / Sec or from T ₁ ° C. or more casting temperature represented by Continuous casting with
Hot rolling starts at a temperature of T ₂ ℃ or more, expressed as T ₂ = 400 × Zr% + 350, and then works while cooling at a cooling rate of 10 ℃ / Sec or more, and winds at a temperature of 150 ℃ or less. A method for producing a high-strength heat-resistant aluminum alloy for electric conduction, comprising aging at 300 to 450 ° C. for 10 to 200 hours and then performing cold working with a surface reduction of 60% or more.