JP2808497B2 - High strength, high toughness and low coefficient of linear expansion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an overhead transmission line (ACS).
The present invention relates to a method for producing an invar wire having high strength, high toughness and low linear expansion coefficient suitable as a core wire of R).

[0002]

2. Description of the Related Art Conventionally, a seven-stranded high-carbon steel wire has been used as a core wire of the overhead transmission line. However, the high-carbon steel wire expands relatively greatly due to a rise in temperature, and causes large droop. Recently, attempts have been made to use an invar wire (Fe-Ni-based alloy) having a low linear expansion coefficient as the core wire. However, the Fe-Ni alloy has a characteristic of a low linear expansion coefficient, but its tensile strength is 90K.
gf / mm2 or less, and the strength and toughness of the core wire of the overhead power transmission line are both insufficient.
Higher toughness has been achieved.

Conventional measures for increasing the strength and toughness of the above Invar wire (Fe—Ni alloy) include, for example, F
Based on an e-Ni alloy, various elements such as Mo, Cr, and Si are added in trace amounts to increase the strength while maintaining the low linear expansion coefficient characteristics. In the process or the final process, or in both the intermediate process and the final process, an invar wire manufacturing method with high strength, high toughness, and low coefficient of linear expansion has been developed and proposed, such as annealing of strain relief to increase the toughness level. ing.

[0004]

The above-mentioned conventional invar wire manufacturing method is based on an Fe-Ni alloy and uses a trace component (M
o, Cr, Si, etc.), the characteristics of the finished product are enhanced, and are largely regulated. In addition, the characteristics are easily affected by subtle changes in the composition. Strain relief annealing performed in the final step or in both the intermediate step and the final step is effective in recovering toughness, but conversely, the high strength and low linear expansion coefficient of the wire return to the values before processing There is a problem that there is a tendency that it is very difficult to adjust each characteristic and it is difficult to meet various demands for product characteristics.

[0005] The present invention has been developed to address the above-mentioned problems, and its object is to produce invar wires (Fe-Ni alloys) and, after the strain relief annealing, Finish processing of properties by wire-making technology to return strength and coefficient of linear expansion to the level before annealing, further recover toughness, and facilitate adjustment of each property to improve workability, product accuracy, and reliability. It is an object of the present invention to provide an invar wire process with improved high strength, high toughness and low coefficient of linear expansion.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a wire rod of a Fe-Ni alloy is drawn into a wire having a predetermined diameter. After the wire is subjected to strain relief annealing, the wire rod is drawn at a small area reduction rate. By performing a slight strain removal process by a straightening roll, the strength and the coefficient of linear expansion of the wire are returned to the levels before annealing, and the toughness is recovered, and the adjustment of the above properties is facilitated.

Further, the wire after the strain relief annealing is drawn at a reduction in area of 2.0 to 8.0%, and the straightening roll removes the strain at a roll diameter / wire diameter of 9.0 to 16.0. By processing, the above-mentioned respective characteristics are further enhanced, and the adjustment of the respective characteristics is facilitated.

[0008]

The wire of a Fe-Ni alloy is drawn into a wire having a predetermined diameter, and the wire is stretched and twisted by strain relief annealing.
The toughness such as winding and unwinding is recovered, and the annealing slightly reduces the strength and increases the linear expansion coefficient, but the strength and the linear expansion coefficient are reduced before annealing due to the light area reduction processing performed after the annealing. Level, and furthermore, the toughness is recovered to a level that does not pose a practical problem by light strain removal by a straightening roll, and the wire drawing with the light area reduction after annealing and the straightening are performed. The light distortion removal processing by the roll is a finishing step by a mechanical wire-making technique, and the product characteristics can be easily adjusted with high accuracy and finely to obtain various product characteristics.

In the above-mentioned Invar wire manufacturing method, the wire reduction rate in wire drawing after strain relief annealing is 2.0 to 2.0%.
By setting the roll diameter / wire diameter in the range of 9.0 to 16.0 in the mild strain relief processing using the straightening rolls to 8.0%, the above-described properties are further improved, and the reliability is improved. You.

[0010]

FIG. 1 is a process diagram showing one embodiment of the present invention, and FIG.
FIG. 3 shows a mechanism diagram of a straightening roll applied to the embodiment, and FIGS. 3 to 9 show explanatory diagrams of characteristics of the embodiment. The alloy composition of the present invention has a weight ratio as shown in Table 1, for example. Fe-Ni
Based on a base alloy, it is configured by adding C, Cr, Mo, Nb and the like.

[0011]

[Table 1] The Invar wire of the present invention is obtained by subjecting an Fe—Ni-based alloy a composed of the components shown in Table 1 to casting 1, forging 2, wire drawing 3, peeling 4, etc. as shown in FIG. For example, 6.
An intermediate processing step of wire-drawing a wire a1 of 5 mmφ and strain-annealing the wire a1, and wire-drawing the wire a1 into a wire-drawing pretreatment 6, wire-drawing 7, cleaning 8, and wire a2 of a predetermined diameter. Then, the wire a2 (or a1) formed into a predetermined diameter and subjected to the strain relief annealing 9 (or 5) is subjected to a pre-drawing treatment 11 by a conventional final step of strain relief annealing 9 of the wire a2. Wire forming process 12 (hereinafter referred to as skin pass processing) with a small area reduction rate, and further, light strain removing process 13 by straightening rolls 20 to produce an invar wire method of high strength, high toughness and low linear expansion coefficient. I have. Further, in the above-mentioned invar wire manufacturing method, the area reduction rate of the wire drawing 12 is 2.0 to
8.0%, and the high-strength, high-toughness, and low-linear-expansion invar wire manufacturing method is adopted, in which the roll diameter / wire diameter of the straightening roll 20 in the straightening roll 13 is 9.0 to 16.0. .

Each of the steps from casting 1 to strain relief annealing 9 and the like is an example of a conventional manufacturing method for producing an Invar wire, and the present invention is not limited to the above-described steps, and is not limited to the above-described steps. After the strain relief annealing 9 in the final step or the strain relief annealing 5 in the intermediate step as required, the wire a2 is subjected to a wire drawing pretreatment 11, a wire drawing process 12 with a light area reduction (skin pass process). In addition, there is a feature that a finishing process including a process of a mild strain removing process 13 by the straightening roll 20 is performed.

In the method for producing an invar wire having a high strength, a high toughness and a low coefficient of linear expansion according to the present invention, as shown in the figure, prior to skin pass processing 12, wire drawing pre-treatment 11 is performed by conventional appropriate means. Is performed at a very light area reduction rate by a conventional appropriate wire drawing means, and the straightening rolls 2 formed in a plurality of stages as shown in FIG.
With 0, a sufficient effect can be obtained.

More specifically, an Fe—Ni alloy is
When wire drawing is performed as shown in FIG. 3, the coefficient of linear expansion is small,
Although the strength gradually increases, the toughness such as elongation, twisting, winding and unwinding tends to decrease. Therefore, in the conventional invar wire manufacturing, as a means for recovering the toughness, wire drawing is performed up to the step of intermediate working or final working, or after the said step, strain relief annealing 5,9 is performed.
Then, the elongation of the wire, torsion, toughness such as winding and unwinding is restored as shown by the dotted line, but the annealing is
The decreasing linear expansion coefficient and the increasing strength tend to be reversed before processing as shown by the dotted line. Also,
In order to obtain a wire having a high strength and a low coefficient of linear expansion, it is necessary to increase the degree of work (increase the area reduction rate). However, if the degree of work is increased, the degree of deterioration in toughness increases, and subsequent strain relief annealing is performed. Recovery of toughness due to the toughness is difficult, and to recover the toughness, it is necessary to increase the degree of annealing, that is, to increase the annealing temperature and lengthen the annealing time, but this is also regulated within a range that maintains a predetermined linear expansion coefficient and strength. You.

[0015] Therefore, the degree of processing to achieve high strength and low linear expansion coefficient is limited to the range in which toughness is recovered by annealing and strength and linear expansion coefficient are maintained, and the resulting strength and linear expansion coefficient are limited. Maximum and minimum values. As described above, conventionally, for high strength, high toughness and low linear expansion coefficient of Invar wire,
In order to raise the processing limit by performing processing such as wire drawing and strain relief annealing, trace amounts of various elements have been added, and improvements have been made by adjusting the components. In contrast, the present invention
High strength and high toughness are obtained by performing processing 12 such as wire drawing with a very light area reduction rate and straightening roll processing 13 for lightly removing strain on a wire rod made of an Fe-Ni alloy alloy after annealing. And a wire made of an Fe-Ni alloy having a low linear expansion coefficient, that is, an invar wire a3.

The degree of work such as drawing and the strength and the coefficient of linear expansion after annealing have a relationship as shown in FIGS. 4 and 5, and the strength rapidly increases in the early stage of working (FIG. 4), and the coefficient of linear expansion is It drops sharply (FIG. 5). In addition, the degree of work such as drawing after annealing and the toughness such as elongation, torsion, winding and unwinding have a relationship as shown in FIG. 4, and the toughness sharply decreases in the early stage of working. The decrease is recovered to a practically acceptable level by the straightening roll processing 13, and although the strength is slightly reduced by the straightening roll processing, it has little effect on the linear expansion coefficient and is effective in recovering the toughness at the beginning of the processing. Means.

Therefore, in the above embodiment of the present invention, Fe-
First, a wire a2 (or a1) formed by rolling a Ni-based alloy to a predetermined diameter is annealed 5 in an intermediate processing step.
Alternatively, it is processed by drawing or the like to a predetermined diameter without annealing so as to have a high strength and a low linear expansion coefficient. Next, the strain relief annealing 9 restores toughness such as elongation, torsion, winding and unwinding. At this time, a slight decrease in strength and a rise in linear expansion coefficient occur due to the recovery of toughness. However, after the strain relief annealing, processing such as wire drawing with a very light reduction rate (skin pass processing) 12
, The strength and the coefficient of linear expansion are returned to the same level as before annealing. Although the toughness is reduced again by the skin pass processing 12, the straightening roll processing 13 is further performed.
The toughness is restored to a practically acceptable level.

The Fe—Ni-based alloy having the composition shown in Table 1 was 6.5 m in each step of casting, forging, wire drawing, and peeling.
An invar wire having a diameter of 2.48 mm and 3.38 mm was manufactured by processing the wire in the process shown in FIG. In the above-mentioned processing, annealing is performed at an appropriate temperature of 500 ° C. or more, and skin pass processing is performed with a reduction in area of 2.0 to
It is performed at about 8.0%, and the straightening roll processing is D /
d = 9.0 to 16.0 (diameter D of straightening roll, diameter d of Invar wire), 2.48 mmφ and 3.38 mmφ
6 to 9 were obtained.

As shown in FIGS.
Is preferably performed at a reduction of area of about 2.0 to 8.0%, and as shown in FIGS. 6 and 7, the ratio of the diameter D of the straightening roll to the diameter d of the invar wire, D / d, is 9. It is preferable to perform strain relief processing in the range of 0 to 16.0, and the invar line 2.4 is used.
The measurement result of each wire property of 8 mmφ is shown in FIG. 7, and the measurement result of each wire property of 3.38 mmφ invar wire is shown in FIG. 8. As is clear from FIGS. 7 and 8, in the present invention, the strength is about 5 kgf / mm 2. Rise, linear expansion coefficient is 0.5 × 10
⁻⁶ / ° C. decrease, elongation increased by 1.0% or more, torsion became equal to or more, and variation was reduced, and remarkable good results were confirmed in all of strength, toughness, and linear expansion coefficient. ing.

[0020]

According to the present invention, the Fe-Ni-based alloy is drawn into a wire having a predetermined diameter by a conventional appropriate working means, and the wire is subjected to strain removal annealing to elongate the wire. ,
While recovering toughness such as torsion and winding / unwinding, the strength and linear expansion coefficient are returned to the level before annealing by wire drawing with a light reduction in area after annealing, and further, mild straightening by straightening rolls By processing, toughness is restored to a practically acceptable level, and a slight decrease in strength caused by the annealing and an increase in the coefficient of linear expansion are easily and effectively eliminated in the finishing step as described above. The wire drawing process with a small area reduction after annealing and the light strain removing process with the straightening roll are effective finishing processes by mechanical wire drawing technology, and have high strength, high toughness and low linear expansion coefficient. Workability, product accuracy, and reliability have been significantly improved, for example, each characteristic can be easily obtained with high precision and finely adjusted. Further, the wire reduction in wire drawing after strain relief annealing is 2.0 to 2.0%.
By setting the roll diameter / wire diameter to 9.0% to 16.0 in the mild strain relief processing with the straightening rolls to 8.0%, the above-described characteristics are further enhanced, and excellent product accuracy and reliability are achieved. can get.

[Brief description of the drawings]

FIG. 1 is a process diagram showing one embodiment of the present invention.

FIG. 2 is a side view mechanism diagram (A) and a XX view mechanism diagram (B) of a straightening roll applied to the embodiment.

FIG. 3 is a mechanical characteristic diagram of an invar wire formed by wire drawing.

FIG. 4 is a characteristic diagram showing a mechanical change of an invar wire at an initial stage of wire drawing.

FIG. 5 is a characteristic diagram showing a change in a linear expansion coefficient of an invar wire at an initial stage of wire drawing.

FIG. 6 is a graph showing D / d of a straightening roll and elongation characteristics after straightening roll processing.

FIG. 7 is a characteristic diagram of elongation improvement by a straightening roll.

FIG. 8 is a characteristic diagram of each process in the example (2.48 mmφ).

FIG. 9 is a characteristic diagram of each step in the example (2.38 mmφ).

[Explanation of symbols]

a Fe-Ni-based alloy D Roll diameter (straightening roll) d Wire diameter a1, wire 5,9 Strain relief annealing 12 Wire drawing with light area reduction (skin pass processing) 13 Slight strain relief processing with straightening roll (Straightening roll processing) 20 Straightening roll

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B21C 9/00 B21C 1/00 B21D 3/00 C21D 8/06

Claims (2)

(57) [Claims] 1. A wire rod of a predetermined diameter is formed by drawing a Fe—Ni-based alloy, and after annealing for strain relief, the wire rod is drawn with a small area reduction ratio, and further, a straightening roll is used to remove a light strain. A high strength, high toughness and low linear expansion coefficient invar wire manufacturing method characterized by processing. 2. The high-strength, high-toughness and low-linear-expansion coefficient invar wire manufacturing method according to claim 1, wherein the wire after the strain relief annealing is drawn at a reduction in area of 2.0 to 8.0%. Roll diameter / wire diameter = 9.0 to 1 using a straightening roll.
A high strength, high toughness and low linear expansion coefficient invar wire production method characterized by performing strain relief processing at 6.0.