JPH08100242A - Alloy wire with high strength, high toughness and low thermal expansion and its production - Google Patents

Abstract

PURPOSE: To produce a new low thermal expansion alloy wire, that is, an Fe-Ni alloy wire capable of improving toughness while maintaining strength at high level. CONSTITUTION: An Fe-Ni alloy stock, preferably, an alloy consisting essentially of, by weight, 0.1-0.5% C, 35-45% Ni, and the balance Fe and containing <=1.0% Si, <=1.0% Mn, and <=4.0% Mo is used. This alloy is hot-worked, cold-worked at 20-60% reduction of area, recovery-treated at 550-800 deg.C, and then cold-worked at 60-95% reduction of area and finished to the prescribed wire diameter, followed by stress relief annealing at 400-650 deg.C. By this method, characteristics of >=115kg/mm<2> tensile strength, >=3.5% elongation, >=70 times twisting value, and <=6×10<-6> / deg.C (30 to 310 deg.C) coefficient of linear expansion can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-strength and high-toughness Fe-Ni-based high-strength, high-toughness low-thermal-expansion alloy wire for use in core wires for low-sag heat-resistant power transmission lines and a method for producing the same. is there.

[0002]

2. Description of the Related Art In recent years, F having high strength and low thermal expansion coefficient
An e-Ni alloy is, for example, a low sag overhead power transmission line (AC
It is desired to develop it as a line for the SR) center part.
For such applications, Japanese Patent Publication No. 56-45990, Japanese Patent Publication No. 55-41928, Japanese Patent Publication No. 57-19942,
JP-A-55-128565, JP-B-3-21622
Japanese Patent Publication No. 3-21623, Japanese Patent Laid-Open No. 56-14285.
1, JP-A-57-26144, JP-A-58-117.
67 and JP-A-58-11768.
An alloy in which alloy elements such as C, N, Cr, Mo, W, and Ti are added to an e-Ni alloy to increase strength is disclosed. Furthermore, for the purpose of improving the strength and toughness of Fe-Ni alloys, JP-A-58-210126 and JP-B-5-2592.
5, JP-A-57-41350 and JP-B-3-72.
No. 365 and the like disclose a manufacturing method in which strain relief annealing is performed after finish drawing.

The inventors of the present invention have also added Fe-containing Mo.
After the solution heat treatment is performed on the Ni-based alloy, the surface reduction rate is 20.
Japanese Patent Laid-Open No. 4-311548 proposes a method in which after cold working at .about.60%, recovery heat treatment at 550 to 800.degree. C. is performed, and then cold working at a surface reduction rate of 65% or more is performed. This method increases the degree of orientation of the {111} crystal faces by performing solution heat treatment and recovery heat treatment, and as a result,
It is intended to obtain an Fe-Ni based alloy wire which has no twist and high twisting characteristics.

[0004]

The application of the solution heat treatment and the recovery heat treatment described above is extremely effective in improving the twisting characteristics of the Fe-Ni alloy. However, the Fe-Ni alloy wire obtained by the above-mentioned technique is 115 k
When the tensile strength is as high as gf / mm ² or more, in each case, elongation of at most about 3% is obtained, and it cannot be said that the required characteristics are sufficiently satisfied in terms of high toughness. The present invention, in order to respond to the further strengthening, the toughness and the improvement of the twisting property of the Fe-Ni alloy wire, has been recently described in Japanese Patent Laid-Open No. 4-311548.
An object of the present invention is to provide a manufacturing method and a novel high-strength, high-toughness, low thermal expansion alloy wire by improving the Fe-Ni-based alloy wire disclosed in Japanese Patent No. 3,096,981, in which the toughness can be improved particularly while keeping the strength high.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present inventors have studied the alloy composition and the manufacturing method,
The tensile properties, twisting properties, and linear expansion coefficient of Fe-Ni alloy wires obtained by various methods were investigated. As a result, the cross section of the Fe--Ni alloy wire was {1
11} 550 to 800 ° C. capable of orienting crystal faces
In addition to the recovery treatment described above, after finishing to a predetermined wire diameter, strain relief annealing at 400 to 650 ° C. is performed to maintain the strength of the conventional material and the stable twisting property. It has been found that a low expansion alloy wire rod having excellent toughness characteristics exceeding that of the above can be obtained.

That is, the manufacturing method of the present invention uses Fe--Ni
After hot-working a system alloy material, cold working with a surface reduction rate of 20 to 60%, recovery treatment at 550 to 800 ° C., and then cold working with a surface reduction rate of 60 to 95% And a strain relieving annealing at 400 to 650 ° C. are performed after finishing to a predetermined wire diameter to obtain a high strength and high toughness low expansion alloy wire.

Preferably, after the hot working or during the cold working after the hot working, a solution treatment is performed at a temperature of 1010 to 1150 ° C., and then a cold working with a surface reduction rate of 20 to 60% is performed. After the addition, a recovery treatment of 550-800 ° C is applied,
After that, cold working with a surface reduction rate of 60 to 95% is added to finish to a predetermined wire diameter, and then strain relief annealing at 400 to 650 ° C. is performed.

A specific preferable composition of the Fe-Ni alloy material applied to the present invention is 0.1% by weight or more and 0.1% by weight or less.
5% or less, Ni 35% or more and 45% or less, balance Fe as a basic component, Si 1.0% or less, Mn 1.0% or less, Mo
It is characterized by containing 4.0% or less.

Further, Cr is replaced by 3.0% or less and a part of Ni is replaced by Co10% or less, and Ni + Co is replaced by 35% or more and 45% or more.
% Or less, W4.0% or less, V0.5% or less, Nb0.5
%, One or more elements selected from the group below,
The addition of alloying elements containing B of 0.02% or less is effective in obtaining high strength, high toughness and low thermal expansion characteristics.

The high strength, high toughness, low thermal expansion alloy wire of the present invention obtained by the above-described manufacturing method of the present invention is Fe-Ni.
This is a series alloy and has a tensile strength of 115 kgf at the final processed wire diameter.
/ Mm ² or more, elongation 4.0% or more (gage length = 250 m
m), twist value 70 times or more (distance between grips = self wire diameter x 1
300 mm), linear expansion coefficient ⁶ × 10- 6 / ℃ (30~310
It is a high-strength, high-toughness, low-expansion alloy wire having a temperature of (° C. The composition range of the specific preferred high-strength, high-toughness, low-expansion alloy wire of the present invention is in agreement with the composition range of the above-mentioned Fe-Ni alloy material.

[0011]

As described above, one of the features of the present invention is that the recovery treatment is performed during the cold working, and the recovery treatment is performed after the cold working.
It is to perform strain relief annealing in a specific range of 0 to 650 ° C. One of the greatest features of the present invention is the recovery treatment. By performing the recovery treatment, many dislocations introduced by cold working are rearranged in the longitudinal direction of the alloy wire to form sub-grain boundaries. . At that time, carbides of Mo and Cr are finely precipitated at the sub-grain boundaries and have a function of pinning the sub-grain boundaries. Due to this effect, the recrystallization temperature is raised, and after the final cold working, a structure having a high degree of orientation of the {111} crystal plane is obtained in the cross section of the alloy wire. By gathering {111} crystal planes in the cross section of the alloy wire after the final cold working, it is possible to obtain high strength and stable twist when applying stress relief annealing which is another important feature of the present invention. It is possible to obtain high toughness (elongation) while maintaining the rolling characteristics.

In the present invention, the reduction ratio of the cold working performed before the recovery treatment needs to be at least 20% or more, and if it exceeds 60%, the recovery and recrystallization temperatures are lowered, and the reduction temperature is lower than the carbide precipitation temperature range. And the degree of orientation of the {111} crystal plane is reduced. Therefore, the reduction rate of the cold working before the recovery treatment is specified to be 20 to 60%. Further, regarding the recovery treatment temperature, dislocation rearrangement does not occur at a temperature lower than 550 ° C., and conversely, when it exceeds 800 ° C., recrystallization occurs and dislocation disappears, and carbide becomes coarse, and subsequent cold working is performed. Since the work hardening degree at that time becomes small and the alloy wire having the target tensile strength cannot be manufactured, the recovery treatment temperature is 55
It is limited to the range of 0 to 800 ° C.

As described above, the stress relief annealing, which is an important feature of the present invention, has a {1
11} Due to the aggregation of crystal planes, the tensile strength increased by the final cold working does not drop below the target value, and the toughness is greatly improved while maintaining stable twisting characteristics. Is obtained. This strain relief annealing temperature is
Although it depends on the size of the cold working rate, for a working rate of 60 to 95%, it is not possible to expect sufficient improvement in toughness at a temperature of less than 400 ° C, and when the temperature exceeds 650 ° C, the tensile strength is extremely lowered. And the target tensile strength cannot be obtained,
The range was limited to 400 to 650 ° C.

Further, the cold working carried out after the recovery treatment in the present invention is carried out in order to increase the tensile strength, and in order to obtain the target tensile strength, a surface reduction rate of at least 60% or more is indispensable. However, even if strong working exceeding 95% is performed, the tensile strength does not increase so much and the number of unnecessary wire drawing steps increases, which is not economical, so the upper limit was kept at 95%.

In a preferred embodiment of the present invention, the solution treatment is performed after hot working. The solution treatment performed after hot working is performed to remove the strain generated during hot working. This has the function of eliminating the variation in strain in the longitudinal direction of the wire and stabilizing the characteristics at the final wire diameter. Recrystallization occurs at a solution treatment temperature of 10
Decarburization and grain coarsening are less likely to occur at 10 ° C or higher 11
It is desirable to set the temperature to 50 ° C or lower.

Only by the manufacturing method of the present invention described above,
Fe-Ni based alloy, tensile strength 115kgf / mm ² or more at the final processed wire diameter, elongation 3.5% or more (gage length =
250 mm), or more twisting value 70 times (distance between grips = self wire diameter × 100 mm), linear expansion coefficient ⁶ × 10- 6 / ℃ (30~3
It is possible to obtain a high strength, high toughness, low expansion alloy wire having a temperature of 10 ° C. or less.

Next, the reasons for defining the preferred alloy composition of the present invention will be described. C, together with Mo described below, has a function of significantly enhancing the cold work hardening ability of the alloy wire of the present invention.
The C content necessary for this is at least 0.1% by weight, but excessive addition of C exceeding 0.5% leads to an increase in the coefficient of thermal expansion, so the C content is 0.1 to 0. Limited to 5%.
Si and Mn are included in the alloy of the present invention as deoxidizing elements. However, since excessive Si and Mn increase the coefficient of thermal expansion,
The addition was suppressed to 1.0% or less in each case.

Of the many strengthening elements, Mo has the highest hardening ability by cold working when it is added in combination with C. This is Mo which is an interstitial solid solution strengthening element in a solid solution state.
It is considered that this is due to the interaction between C and the substitution type solid solution strengthening element, and partly to precipitate as fine carbide of Mo ₂ C. The fine secondary carbides are precipitated along the sub-grain boundaries during the recovery heat treatment after the cold working after the solution heat treatment, and the dislocations are rearranged in the longitudinal direction by the cold working thereafter, and the {111} crystals are formed. It contributes to improving the toughness without increasing the degree of orientation of the surface and reducing the strength. However, excessive addition of Mo also causes an increase in the thermal expansion coefficient, so 4.0% was made the upper limit.

Cr is an element similar to Mo and contributes to strengthening for the same reason as Mo, but excessive addition increases the coefficient of thermal expansion more than Mo, so 3.0% was made the upper limit.
B is the same as the secondary carbide of Mo in the alloy wire of the present invention.
It has the effect of segregating to the sub-grain boundaries during the recovery heat treatment and pinning the sub-grain boundaries, and expanding the appropriate range of the recovery heat treatment temperature.
However, excessive addition exceeding 0.02% deteriorates hot workability, so B is limited to 0.02% or less. W,
V and Nb are elements that combine with C to form a carbide and contribute to the improvement of work hardening ability in cold working. However, excessive addition deteriorates hot workability, so W is 4.0. %
Hereinafter, V is limited to 0.5% or less and Nb is limited to 0.5% or less.

Various additive elements for strengthening the Fe-Ni alloy are conceivable other than the above-mentioned C, Cr, Mo, W, V and Nb, but carbides such as Ti, Ta, Hf and Zr having a high affinity with C. The forming element produces lumpy hard primary carbides,
It is not preferable to add excessively to the alloy wire of the present invention, because it is likely to cause defects during cold working and cause variations in twist value. Therefore, it is desirable to suppress the upper limit of each of these elements to about 0.5%.

In the present invention, the content of Ni has a great influence on the thermal expansion characteristics. Especially from room temperature to 230 ℃
For the purpose of lowering the average coefficient of thermal expansion up to
If the amount is less than 35%, the transition point, which means the temperature at which the low thermal expansion characteristic disappears, shifts to the low temperature side, and the thermal expansion coefficient up to 230 ° C. increases. On the other hand, when Ni exceeds 45%, the transition point shifts to the high temperature side, but the thermal expansion coefficient on the low temperature side becomes high as a whole, so that the thermal expansion coefficient up to 230 ° C. also increases. For the above reasons, Ni is 35
% To less than 45%.

By substituting a part of Ni for Co,
The coefficient of thermal expansion up to 230 ° C. can be further reduced as compared with the case of using Ni alone. However, Co is more likely to cause martensitic transformation during cold working than Ni and has a strong effect of destabilizing the austenite phase. Therefore, when Co is added in combination with Ni, Co is present in an amount of 35% or more and less than 45% of Ni and 1
Co of 0% or less is limited to 35% or more and less than 45% of Ni + Co.

Further, gas components such as O and N form inclusions in the alloy, which also causes variations in twist values.
The alloy wire of the present invention is limited to 0.01% or less. A added for the purpose of deoxidation and desulfurization
Elements such as 1, Mg, Ca, and REM are usually contained, but the amounts shown below may be contained in terms of characteristics. Al, REM ≦ 0.1% Mg, Ca ≦ 0.0
2%

[0024]

【Example】

(Example 1) A Fe-Ni alloy having the composition shown in Table 1 was melted, hot-forged and hot-rolled into a wire having a diameter of 9.5 mm, and coiled under various wire drawing and heat treatment conditions shown in Table 1. A wire rod was produced. At this time, the cold wire drawing has an approach angle 2α = 12 °, a bearing length of 20 to 50% × D (D
= Wire drawing diameter) and using a die made of cemented carbide, wire drawing was performed at a surface reduction rate of about 20% per pass. The tensile properties, twisting properties, and thermal expansion properties of these wires were investigated. The elongation in the tensile test was measured at a gauge length of 250 mm, and the tensile strength and the elongation were obtained by averaging 10 wires. In the twisting test, the distance between the grips is 100 times the self-diameter, and the rotation speed is 60r.
The number of twists until breakage was measured at 5 pm for each condition, and the average value and standard deviation were obtained. Table 3 shows the characteristic test results of the wire rods manufactured under each manufacturing condition together with comparative examples.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

From Table 3, it can be seen that the wire rod manufactured by the manufacturing method of the present invention in which both the recovery treatment and the strain relief annealing are applied has a high strength, a large elongation and a high toughness value.
On the other hand, the sample L of the comparative example without the stress relief annealing and the sample M of the comparative example in which the stress relief annealing temperature is lower than the range of the present invention.
Although the tensile strength was equivalent to the value of the present invention example, the elongation value was as low as 2% at most, and the toughness was inferior to the present invention example. Further, when looking at the wire rods G (560 ° C.) and I (480 ° C.) of the present invention having different strain relief annealing temperatures,
In addition to maintaining a high elongation value, high tensile strength could be obtained without deteriorating the twisting property. From the results of the wire rods G and I of the present invention, it is understood that it is possible to manufacture the wire rod by adjusting the strength and toughness by adjusting the strain relief annealing temperature corresponding to the final step.

In Comparative Example Q without the recovery treatment, the degree of aggregation of the {111} crystal planes in the cross section of the alloy wire was low, and a large elongation was obtained even when the strain relief annealing similar to the present invention was performed. However, the twist value is low and the variation is large.

(Example 2) Fe-Ni having the composition shown in Table 4
After melting a system alloy and making it into a wire having a diameter of 9.5 mm by hot forging and hot rolling, an Fe-Ni wire having a different composition was produced under the same manufacturing conditions as G in Table 2, and was used as Example 1. The same accuracy test was performed. Table 5 shows the accuracy test results.

[0031]

[Table 4]

[0032]

[Table 5]

All of the alloy wire rods have high strength and high toughness, and the Fe-N is used in the present manufacturing method in which all the heat treatments of solution treatment, recovery treatment, and strain relief annealing are performed as described above.
It can be seen that this is an excellent method for producing an i-based alloy wire rod.

[0034]

EFFECT OF THE INVENTION Fe obtained by the production method of the present invention
The -Ni-based alloy wire has high strength, has less variation in twisting characteristics, and has an excellent twisting value. Further, it has a higher toughness than that of the Fe-Ni-based alloy wire. , Which has even more excellent toughness. Therefore, the power transmission capacity is higher than that of the conventional low-sag transmission line, and the material is suitable as a material for a transmission line for the purpose of highly reliable transport of electric power.

Claims (13)

[Claims] 1. An Fe-Ni alloy, which has a tensile strength of 115 kgf / mm ² or more at the final processed wire diameter, an elongation of 3.5% or more (gauge length = 250 mm), and a twist value of 70 times or more ( the distance between grips = self wire diameter × 100 mm), linear expansion coefficient 6 × 10- ⁶
Strength / high toughness low expansion alloy wire having a temperature of / ° C (30 to 310 ° C) or less. 2. The alloy composition of the Fe—Ni alloy wire is such that the weight percentage of C is 0.1% or more and 0.5% or less, and Ni is 35% or more and 45%.
% Or less, the balance Fe as a basic component, Si 1.0% or less, M
The high-strength, high-toughness low-expansion alloy wire according to claim 1, characterized in that the content of n is 1.0% or less and Mo is 4.0% or less. 3. The high-strength, low-thermal expansion alloy wire according to claim 2, which contains Cr in an amount of 3.0% or less. 4. A part of Ni is replaced by Co 10% or less,
The high-strength, high-toughness, low-expansion alloy wire according to any one of claims 1 to 3, wherein the content of Ni + Co is 35% or more and 45% or less. 5. W4.0% or less, V0.5% or less, Nb
The high-strength, high-toughness, low-expansion alloy wire according to any one of claims 2 to 4, which contains one or more elements selected from the group of 0.5% or less. 6. The high-strength, high-toughness low-thermal expansion alloy wire according to claim 2, wherein the content of B is 0.02% or less. 7. An Fe—Ni alloy material is hot-worked and then cold-worked at a surface reduction rate of 20 to 60%, and then at 550 to 800 ° C.
After performing the recovery treatment of No. 6, then cold-working with a surface reduction rate of 60 to 95% to finish to a predetermined wire diameter, 400 to 6
A method for manufacturing a high-strength, high-toughness, low-expansion alloy wire, which comprises performing stress relief annealing at 50 ° C. 8. A Fe—Ni alloy material is subjected to hot working or 1010 to 1150 ° C. during cold working after hot working.
Solution treatment is performed at the temperature of, and then the area reduction rate is 20 to 60.
% Cold working, then 550 to 800 ° C. recovery treatment, then 60 to 95% surface reduction cold working to finish to a predetermined wire diameter, then 400 to 650 ° C. strain relief annealing. A method for producing a high-strength, high-toughness, low-expansion alloy wire, which comprises: 9. The Fe—Ni alloy material is C in weight%.
0.1% or more and 0.5% or less, Ni 35% or more and 45% or less, balance Fe as a basic component, Si 1.0% or less, Mn
The method for producing a high-strength, high-toughness low-expansion alloy wire according to claim 8, wherein the content is 1.0% or less and Mo is 4.0% or less. 10. The method for producing a high strength and high toughness low thermal expansion alloy wire according to claim 9, wherein the content of Cr is 3.0% or less. 11. The high-strength, high-toughness, low-expansion alloy according to claim 9, wherein a part of Ni is replaced with Co of 10% or less and Ni + Co is 35% or more and 45% or less. Wire manufacturing method. 12. W 4.0% or less, V 0.5% or less, N
The method for producing a high-strength, high-toughness, low-expansion alloy wire according to any one of claims 9 to 11, which contains one or more elements selected from the group having a b content of 0.5% or less. 13. The method for producing a high strength and high toughness low thermal expansion alloy wire according to claim 9, wherein the content of B is 0.02% or less.