JPH06200352A - High strength alloy with low thermal expansion - Google Patents

Abstract

PURPOSE:To produce a high strength low thermal expansion alloy having tensile strength equal to that of piano wire and high twisting property and further having low coefficient of thermal expansion over the range between ordinary temp. and about 300 deg.C. CONSTITUTION:This alloy is a high strength low thermal expansion alloy having a composition which consists of, by weight, 0.06-0.50% C, <=1.0% Si, <=2.0% Mn, 22.8-29.2% Ni, 9.3-20% Co, and the balance Fe except impurities and where the relationship between Ni and Co satisfies 58-(5/3)Ni<Co<=86.25-(5/2)Ni and also having a structure containing austenite phase and martensite phase resulting from strain induced transformation as main phases. If necessary, prescribed amounts of Cr, Mo, W, B, Mg, Ca, V, Ti, Nb, Ta, Hf, Zr, Al, and REM can be added.

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 low-thermal-expansion alloy used for precision machine parts which are affected by temperature rise during use, core wires for low-sag heat-resistant power transmission lines, and the like.

[0002]

2. Description of the Related Art Conventionally, a steel core aluminum stranded wire (ACSR wire) has been used for an overhead power transmission line, but it has been replaced by a conventional steel core aluminum stranded wire due to the recent increase in power demand and soaring land prices. Alloy wires with high strength and low coefficient of thermal expansion have been desired. In this application, the high-strength, low-thermal expansion alloy is used as the core material of the aluminum stranded wire, so the work of twisting and bundling multiple wires is required. As a method for evaluating the performance of this twisting work, a twisting test in which one end of the wire is fixed and the other end is twisted is carried out, and the twisting value is required.

For such applications, Japanese Patent Publication No. 56-45
990, JP-A-55-41928, and JP-B-57-1.
7942, JP-A-55-122855, JP-A-55
-128565, JP-A-55-131155, JP-A-56-142851, JP-A-57-26144,
JP-A-58-11767 and JP-A-58-1176
Fe-Ni alloys such as No. 8 have been proposed. further,
For the purpose of improving the strength and twisting properties of these alloys, high-strength and low-thermal expansion alloy wires such as Japanese Patent Publication No. 60-34613, Japanese Patent Publication No. 2-15606, Japanese Patent Publication No. 2-41577 and Japanese Patent Publication No. 2-55595. A method for producing (ACIR wire) or alloy wire is disclosed.

[0004]

The conventional high-strength low-thermal expansion alloys described above all contain Ni or Ni + Co.
In the range of up to 50%, and further includes C and N interstitial solid solution strengthening elements, several substitutional solid solution strengthening elements such as Cr and Mo, and T.
The alloy composition contains several precipitation strengthening elements such as i and Nb within a range that does not impair the low thermal expansion characteristics, and the balance is Fe. In the case of solution heat treatment or annealing heat treatment, all of these alloys have good twisting characteristics, but the tensile strength is at most 50-80 kgf / mm ² , and in this state, low sag Not suitable for use as a core wire for overhead power lines. However, all of these alloys have work hardening ability of 36% Ni-F which is a conventional low thermal expansion alloy.
It is larger than the e alloy and the 42% Ni-Fe alloy, and a tensile strength of 100 to 130 kgf / mm ² was obtained by cold working, and it was partially put to practical use.

However, the strength of the piano wire used as the core wire of the conventional steel core aluminum stranded wire is 170 kgf / mm ² class, and the transmission capacity of these power transmission lines is rebuilt on the steel tower. 170kg to increase without
A low thermal expansion alloy wire that has the same tensile strength as a piano wire of f / mm ² class was required. In addition, the conventional high-strength low-thermal expansion alloy wire described here has a large decrease in the twisting property, which represents the deformability against torsion, simply by subjecting it to strong working in the cold region. A method has been proposed in which the alloys disclosed in the above-mentioned publications are wire-drawn by various complicated productions in order to achieve both the rolling characteristics.
For example, Japanese Patent Publication No. 60-34613 and Japanese Patent Publication No. 2-15
In No. 606, stress relief annealing is performed before the cold working or in the middle of the cold working to try to achieve both strength and twisting property. It is disclosed in these manufacturing methods that good twisting characteristics are obtained by removing the surface strain caused by peeling by annealing heat treatment.

On the other hand, the alloy wires disclosed in Japanese Examined Patent Publication No. 2-41577 and Japanese Examined Patent Publication No. 2-55495 take substantially the same manufacturing process as those of Japanese Examined Patent Publication No. 60-34613 and Japanese Examined Patent Publication No. 2-15606. However, it is stated here that the MoC carbide generated during annealing after cold working contributes to the improvement of strength and twisting characteristics. However, Tokuhei 2-
One of the inventors of No. 41577 and Japanese Examined Patent Publication No. 2-55495 describes “Effect of processes of drawing on torsional
property of high-tensile strength Invar alloy wir
e '' (Wire Journal International vol.21, No.4 (1988), P8
The subject is 4) and touches on the improvement of the twisting characteristic.

In this paper, the improvement of the twisting property is not sufficient only by carrying out an annealing heat treatment for precipitating Mo2C carbide after cold working, and especially in the hardness distribution of the cross section of the alloy wire after drawing, the central part It has been reported that a special jig called a Christopherson tube is required to reduce the drawing angle of the die and to improve the lubricity so that the hardness of the steel becomes the highest. However, increasing the twisting characteristics by using a special jig called a Christopherson tube to reduce the die pull-out angle and lubricity increases the number of pulling passes (small pull-out angle). In that case, the frictional resistance becomes large, and it is not possible to obtain a high surface reduction rate per pass.) It also takes time to change the process of the line, and it is difficult to manufacture alloy wires with a total length of several kilometers. This is an inefficient manufacturing method.

From this point of view, the present inventor has proposed, in Japanese Patent Application No. 4-102564, an alloy of 54Co-9Cr-remaining Fe called stainless invar and an alloy of 31Ni-6Co-remaining Fe called superinvar. , An alloy in which an alloy having a composition in which the austenite phase is more unstable is connected in a proportional relationship, and further, an appropriate amount of C, which greatly contributes to the work hardening of the austenite phase and the improvement of the strength of work-induced martensite, has been proposed. This alloy has higher strength than conventional Invar wire, rather it has tensile strength close to that of a piano wire, and does not require a complicated annealing process. The same level of twist value is obtained. However, with this alloy, although a low coefficient of thermal expansion is certainly obtained in the temperature range from normal temperature, which is a normal temperature range of low-slack overhead power transmission lines to about 200 ° C., it is 300 from the normal temperature, which is the maximum use temperature range. It was found that the thermal expansion coefficient in the temperature range of ℃ was significantly higher than that of conventional low-slack overhead transmission lines.

In view of the above problems, the object of the present invention is to provide a conventional Fe--Ni-based high strength low thermal expansion alloy having a strength of 100 to 130 k.
comparable to the piano wire of the above far more than gf / mm ² 170kgf / mm ²
It has high tensile strength, stable and high twisting characteristics without complicated process, and low thermal expansion from ordinary temperature to about 300 ℃ in the temperature range of conventional low-slack overhead power transmission line. It is to provide a high strength low thermal expansion alloy having a coefficient.

[0010]

The present inventors have made various alloys into Fe-Co-Ni-based alloys for the purpose of achieving both high strength comparable to that of a piano wire and low coefficient of thermal expansion in a wide temperature range. The tensile properties, twisting properties, and coefficient of thermal expansion of the alloy wire were investigated using a hot forging material with a composition containing elements. As a result, the transition point that represents the change in the curvature of the thermal expansion curve (the transition point is almost equivalent to the Curie temperature, the Invar characteristic is obtained in the temperature range up to the transition point, and the coefficient of thermal expansion is low, but it exceeds the transition point. In the temperature range, the coefficient of thermal expansion increases sharply), but in the alloy composition group shown in Japanese Patent Application No. 4-102564, it is located around 200 ° C., and therefore, the maximum temperature range of use of the low sag overhead transmission line is From normal temperature,
It was found that in the temperature range of 300 ° C, the coefficient of thermal expansion is clearly higher than that of the conventional low-slack overhead power transmission line. Therefore, Fe which can use the same method as that of Japanese Patent Application No. 4-102564 for strengthening by utilizing the transformation induced martensite transformation is Fe.
As a result of studying a region where the transition point can be further increased in the composition range of the —Co—Ni alloy, high strength is obtained in a region where the Ni + Co amount is relatively high and the Cr + Mo + W amount is relatively low compared to Japanese Patent Application No. 4-102564. It has been found that there is an alloy composition region that achieves both low thermal expansion coefficient and.

That is, the first aspect of the present invention is, in% by weight, C0.06 to 0.50%, Si 1.0% or less,
Mn 2.0% or less, Ni 22.8 to 29.2%, Co
In the case of 9.3 to 20%, the relationship between Ni and Co is 58- (5 /
3) Ni <Co ≦ 86.25− (5/2) Ni,
The balance is a high-strength, low-thermal-expansion alloy characterized by having a composition of Fe excluding impurities, and having a structure having at least two phases of an austenite phase and a martensite phase generated by work-induced transformation. % By weight, C
0.06-0.50%, Si1.0% or less, Mn2.0
% Or less, Ni 22.8 to 29.2%, Co 9.3 to 20
%, The relationship between Ni and Co is 58− (5/3) Ni <Co
≦ 86.25− (5/2) Ni, and further Cr2.
5% or less, Mo 3.5% or less and W 5% or less 1 type or 2 types or more Cr + 0.54Mo + 0.28W ≦ 2.
It is a high-strength low-thermal expansion alloy characterized by having a composition containing Fe in the range of 5 with the balance being Fe, and having at least two phases of an austenite phase and a martensite phase generated by work-induced transformation. .

If necessary, one or more of B0.02% or less, Mg0.02% or less and Ca0.02% or less are added to the alloys of the first and second inventions. can do. In addition, if necessary by weight,
One or two of V, Ti, Nb, Ta, Hf and Zr
It is also possible to contain a total of 1% or less of seeds or more. Further, it is possible to add one or two of Al 0.2% or less and REM 0.2% or less in weight%. Furthermore, the austenite phase of the high strength low thermal expansion alloys of these compositions is
A structure having at least 65% or more of the entire phase after cold working is desirable for obtaining low thermal expansion characteristics.

[0013]

The reasons for limiting the components of the chemical composition range of the high strength and low thermal expansion alloy of the present invention will be described below. In the alloy of the present invention, C is an element that contributes most to work hardening of the austenite phase during cold working and improvement of the strength of work-induced martensite. Further, Ni or Co may be partially substituted as the austenite stabilizing element. In order to obtain such an effect, C needs to be at least 0.06%, but on the contrary, C exceeding 0.50% excessively stabilizes the austenite phase and hardly causes martensitic transformation. In addition, the thermal expansion coefficient is increased. Therefore, the C content is limited to 0.06 to 0.50%. A more desirable range of C is 0.10 to 0.30%.

Si and Mn are included in the alloy of the present invention as deoxidizing elements. However, excessive Si and Mn lead to an increase in the coefficient of thermal expansion, so the addition is limited to 1.0% or less and 2.0% or less, respectively. In the alloy of the present invention, Ni and Co are essential elements for imparting Invar characteristics to the alloy together with Fe constituting the balance. The composition range of Ni and Co is such that good low thermal expansion characteristics and high tensile strength can be achieved in a wide temperature range from room temperature to about 300 ° C. only within a range satisfying the mutual relationship in the present invention range of FIG. Is. The upper right or the amount of Ni is 29.
When the alloy composition in the region A exceeds 2%, the austenite phase becomes stable even when subjected to strong cold working, and the tensile strength is at most about 140 kgf / mm ² , and further work hardening cannot be expected. On the other hand, the lower left side and the Ni content of 2 are larger than those of the present invention region
In the region B of 9.2% or less, high strength is obtained by the work-induced martensitic transformation, as in the alloy of the present invention.

However, since the alloy in the region B has a low transition point, a low coefficient of thermal expansion can be obtained up to about 200 ° C., but the coefficient of thermal expansion between 200 ° C. and 300 ° C. rapidly increases. The thermal expansion characteristics are inferior to those of the alloy of the present invention. Further, in the region C where Co exceeds 20% and is sandwiched between the region A and the region B, high strength is obtained by the work-induced martensite transformation, and the transition point is high, as in the region B and the alloy of the present invention. Since the coefficient of thermal expansion becomes too high, the coefficient of thermal expansion becomes high at any temperature from room temperature to 300 ° C. Therefore, Ni, Co of the alloy of the present invention
As shown in FIG. 1, the amount of Ni is 22.8 to 29.2%.
And 9.3 to 20% of Co and are limited to the range satisfying the following relationship between Ni and Co. 58- (5/3) Ni <Co ≦ 86.25- (5/2) Ni (1) From the viewpoint of strength, thermal expansion coefficient, and alloy price, a particularly desirable range of Ni and Co is 25. 0-29.2% Ni and 1
It is a region containing 1 to 15% of Co and satisfying the expression (1).

Cr, Mo and W are elements belonging to the same group, and both stabilize the austenite phase which is the base, and at the same time, they improve the work hardening ability of the base as solid solution strengthening elements and partly as carbide precipitation strengthening elements. It can be added alone or in combination depending on the requirement. Further, these elements have the effect of increasing the high temperature strength around 300 ° C. which is the maximum operating temperature of the low sag heat resistant transmission line. However, since both of these elements greatly reduce the transition point,
2.5% for Cr, 3.5% for Mo and W
In the case of, the transition point drops excessively if it exceeds 5%, and
Since the thermal expansion coefficient between 0 ° C. and 300 ° C. suddenly increases, the upper limit of Cr is 2.5% and the upper limit of Mo is 3.5%.
% And W are limited to 5%. Also,
Since these elements act similarly as solid solution strengthening and precipitation strengthening elements in the atomic ratio, Cr + 0.54Mo +
The upper limit for the sum of 0.28 W is 2.5%. Particularly desirable ranges of Cr, Mo, and W are 1.5% or less, 2.5% or less, and 3.5% or less, respectively, and Cr + 0.
It is within the range of 54Mo + 0.28W ≦ 2.0.

B segregates at the austenite grain boundaries to strengthen the grain boundaries, and is effective in improving the hot workability of the alloy of the present invention and improving the ductility at room temperature. Further, Mg and Ca combine with S to form granular sulfides, and like B, are effective in improving hot workability and improving ductility at room temperature. For these effects, B, Mg, and Ca can be added alone or in combination of two or more, but excessive addition exceeding 0.02% lowers the melting point of the alloy, and conversely B, Mg and Ca are all limited to 0.02% or less because they deteriorate hot workability. As elements for strengthening the Fe-Ni-Co alloy, V, Ti, Nb, which have the same action in terms of solid solution strengthening or precipitation strengthening of fine MC-type carbides, in addition to C, Cr, and Mo, Elements such as Ta, Hf and Zr can be added. V, Ti, Nb, Ta, Hf, and Zr combine with C to form fine primary carbides, strengthen the austenite phase by precipitation strengthening, and partly dissolve in the matrix to form a work solution, which causes work hardening during cold working. Enhance the ability. Because of these effects V,
Ti, Nb, Ta, Hf, and Zr may be added alone or in combination of two or more, if necessary. The effect is exerted from the addition of a small amount.

However, when the sum of the weight percentages of these alloy elements exceeds 1% in total, coarse primary carbides are precipitated and voids are easily generated around the carbides during cold drawing. This causes variations in the twisting characteristics, and the thermal expansion coefficient becomes higher than the strength increasing effect. Therefore, the addition of V, Ti, Nb, Ta, Hf, and Zr is 1 type or 2 types or more and 1% or less in total. Further, Al and REM can be added for the purpose of deoxidation and desulfurization. Although the effect appears from the addition of a small amount of each, since excessive addition makes it difficult to dissolve in the atmosphere, Al,
The upper limit of each addition of REM is 0.2% or less.
Also, gas components such as O and N form inclusions in the alloy,
Similarly, in the alloy wire of the present invention, 0.01% or less is desirable because it also causes variations in twist value. The alloy according to the present invention is a high strength and low thermal expansion alloy composed of the above-mentioned alloy elements and the balance Fe.

Next, in the invention alloy of the present application, the austenite amount is preferably 65% or more. If the amount of transformation of work-induced martensite increases too much and the amount of austenite falls below 65%, the coefficient of thermal expansion becomes too high,
This is because the low thermal expansion characteristics intended by the present invention may not be obtained.

In the alloy of the present invention having the above composition, the austenite phase is almost stable at room temperature even after being rapidly cooled to normal temperature after hot working or solution heat treatment. However, by sufficiently cold working, martensitic transformation is caused by the transformation induced transformation. Work hardening by cold working has a large effect by martensitic transformation in addition to work hardening ability improvement of austenite base by addition of C. Further, when the alloy of the present invention is processed into a wire rod, a stable twist value of 20 times or more can be obtained without performing annealing treatment in the intermediate step of cold drawing. The twist value at this level is equivalent to that of a conventional piano wire, which is
It is speculated that the effect of stress relaxation due to the transformation of the existing martensitic phase existing during cold working or the transformation from the austenite phase to the martensitic phase during twisting is large.

When the base austenite phase is stable even when the Invar alloy is subjected to strong cold working, the coefficient of thermal expansion is low, but the tensile strength is insufficient, or when the wire is cold worked, In a simple cold drawing process, the twisting characteristics may become insufficient. On the contrary, if the austenite phase becomes too unstable, martensite transformation occurs during the cooling process after hot working or after solution treatment, and the Invar property can no longer be obtained. For the reasons described above, in order for the alloy of the present invention to simultaneously obtain high strength, low thermal expansion coefficient and high twist value, it is necessary to use two phases, an austenite phase and a martensite phase generated by work-induced transformation, as main phases. is there.

The reverse transformation temperature of such work-induced martensite to austenite is 550 ° C. or higher, and continuous use around 300 ° C. which is the maximum temperature used as a transmission line is characteristic of the alloy of the present invention. Above, there is no problem. Further, the processing-induced martensite is 400 to 500 such as Al coating treatment and Zn plating treatment in the intermediate and finish manufacturing processes when used as a power transmission line.
Although a part may decompose into carbide and ferrite by heating at ℃, the presence of a small amount of ferrite in the alloy of the present invention has no problem in characteristics. Also, although there is a small amount of carbide phase, there is no problem in terms of characteristics.

[0023]

EXAMPLES Fe-Co-Ni- (Cr having the composition shown in Table 1
+ Mo + W) alloy is melted and hot forged to a diameter of 1
Finished into a 3.0 mm round bar. Then 850 ° C to 98
After being kept at a temperature of 0 ° C. for 30 minutes, water-cooled solid solution treatment and surface peeling were performed to obtain a diameter of 12.3 mm. Further, using this sample, the coefficient of thermal expansion was measured, and the diameter was 4.9 to 3% in the range of the processing rate of 84 to 93.5% by cold drawing.
A 1 mm coil was made. For cold drawing, a die made of WC having a very general approach angle of 12 ° was used, and wire drawing was performed at a surface reduction rate of about 20% per pass.

The wire drawing speed at that time was the same as that of a normal steel wire. Thermal expansion test, tensile test, twist test, etc.
A winding / rewinding test and an amount of austenite in the alloy were measured. The results are shown in Table 2. Regarding the alloy of the present invention, the test results of the wire diameter of the optimum working rate that achieves both the tensile strength of 160 kgf / mm ² or more and the low thermal expansion coefficient up to 310 ° C., and the comparative alloy No. 31 were also 16
Regarding the test results of the wire diameter that obtained the tensile strength of 0 kgf / mm ² or more, further, the comparative alloy Nos. 32 to 34 and the conventional alloy No. 4
For No. 1, processing rate 93.5%, diameter up to 3.1 mm,
The test results at the time of pulling out are described.

The thermal expansion was measured at 30 ° C. with a differential thermal expansion meter.
To 230 ° C. and 30 ° C. to 310 ° C. average thermal expansion coefficients were measured. The elongation in the tensile test was measured at a gauge length of 250 mm, and the average value of 5 pieces was obtained for both tensile strength and drawing. Further, in the twisting test, the gripping distance was set to 100 times the self-diameter, and 10 twisting values until breakage were measured at a rotation speed of 60 rpm to obtain an average value. Regarding the wrapping / rewinding test, it was investigated whether or not the test piece broke when the core wire having 1.5 times the self-diameter was wound / rewound 8 times each, and if there was no crack, it was judged as pass. When the mark was generated, the mark was rejected, and the mark x is shown in Table 2. Further, the cross section of the sample was subjected to X-ray diffraction, and the phase ratio between the amount of austenite and the amount of martensite was calculated by the following formula. Austenite phase (%) = {Iγ / (Iγ + Iα)} ×
100 Iγ = Iγ (111) + Iγ (200) + Iγ (220) + Iγ (311) Iγ (111) is the X-ray diffraction intensity of austenite Iα = Iα (110) + Iα (200) + Iα (220) + Iα (211) Iα (110) is the X-ray diffraction intensity of martensite

[0026]

[Table 1]

Among the alloys shown in Table 1, Nos. 1 to 22 are alloys of the present invention, Nos. 31 to 34 are comparative alloys, and No. 41 is
It is a high strength and low thermal expansion alloy disclosed in JP-A-3-115543. Further, for the alloy of the present invention and the comparative alloy,
The relationship between Ni and Co is shown in FIG. From Table 2, the alloy of the present invention is 160 to 18 after cold working of 84 to 93.5%.
It has a tensile strength of 0 kgf / mm ² and an average coefficient of thermal expansion between 30 ° C and 310 ° C of 5.5 × 10 -6 powers / ° C or less, and a tensile strength equal to or close to that of conventional piano wire. It can be seen that a coefficient of thermal expansion less than 1/2 of that of a piano wire can be obtained (coefficient of thermal expansion of a piano wire α30-310
C: 11.5 to 13 x 10 minus 6 / C).

These characteristics are slightly inferior in thermal expansion coefficient to conventional Fe--Ni based high strength low thermal expansion alloys, for example, conventional alloy No. 31, but marked differences in tensile strength are observed. In order to replace the transmission line without rebuilding the existing steel tower, it is absolutely necessary to have the same strength as the piano wire, so in terms of sag, the conventional Fe-Ni-based high strength low thermal expansion alloy Although it is equivalent to or slightly inferior to the wire, it can be seen that the strength is far higher than that of the conventional Fe-Ni-based high strength and low thermal expansion alloy wire.

[0029]

[Table 2]

Further, it can be seen from Table 2 that the alloy of the present invention has a high twist value and excellent winding / unwinding characteristics. Such effects are brought about by the transformation of the work-induced martensite present during cold working and the austenite phase that occurs during plastic deformation of these various tests to the martensite phase. From Table 2, the alloy of the present invention has an austenite phase and martensite phase ratio of 75 to 90%.
It can be seen that it is composed of an austenite phase of about 10 to 25% and a martensite phase of about 10 to 25% (actually, a small amount of carbide is present as a third phase). Usually, the austenite stable Invar alloy has a lower coefficient of thermal expansion due to cold working, but the alloy of the present invention has an average temperature between 30 ° C. and 310 ° C. after cold working than before cold working. Since all of the thermal expansion coefficients are high, it is clear that cold-working causes work-induced transformation.

On the other hand, as compared with the alloy of the present invention such as Comparative Alloy No. 31, the composition of Ni and Co belonging to the region B of FIG. 1 has a higher tensile strength due to the work-induced transformation like the alloy of the present invention. However, since the relationship between the amount of Ni and Co is not optimized, the transition point is low, and although the coefficient of thermal expansion up to 230 ° C. is as low as that of the alloy of the present invention, it reaches 310 ° C. The coefficient of thermal expansion is clearly higher than that of the alloy. Moreover, when Ni and Co belong to the region B of FIG. 1 like the comparative alloy Nos. 32 and 34, and Cr + 0.54Mo + like the No. 33.
If 0.28 W is higher than the alloy range of the present invention,
In both cases, the austenite phase became too stable, and 93.
Even if cold working with a strength of 5% is applied, no work-induced transformation occurs, and the tensile strength is clearly inferior to that of the alloy of the present invention (Nos. 32 to 34 are all 100% austenite phase). Further, the comparative alloy Nos. 32 to 34 and the conventional alloy No. 41 have a low twisting value of 10 times or less when simply cold-worked after peeling, which makes them suitable for use in the core wire of a transmission line. Becomes unsuitable.

[0032]

As described above, the alloy of the present invention is one rank higher than the conventional low thermal expansion alloy, that is, has a tensile strength equal to or close to that of a piano wire, and is stable as a piano wire even in a simple manufacturing process. A high twist value is obtained, and it is 1 / 100th of a piano wire over a wide temperature range from room temperature to 300 ° C.
It has a low coefficient of thermal expansion of 2 or less. INDUSTRIAL APPLICABILITY The alloy of the present invention enables production of a low sag transmission line which is excellent in reliability and has a higher transmission capacity than a transmission line using a conventional piano wire as a core wire. Therefore, the transmission capacity of the transmission line can be relatively easily obtained. It is possible to increase.

[Brief description of drawings]

FIG. 1 is a diagram in which the relationship between Ni and Co of the alloy of the present invention and the comparative alloy is plotted.

Claims (6)

[Claims] 1. C0.06-0.50%, S by weight%
i 1.0% or less, Mn 2.0% or less, Ni 22.8 to 2
9.2% and Co 9.3 to 20%, the relationship between Ni and Co is 58- (5/3) Ni <Co≤86.25- (5/2).
The composition is Ni, and the balance is Fe except impurities.
A high-strength, low-thermal-expansion alloy having a structure having at least two phases, an austenite phase and a martensite phase generated by work-induced transformation. 2. C0.06-0.50%, S by weight%
i 1.0% or less, Mn 2.0% or less, Ni 22.8 to 2
9.2% and Co 9.3 to 20%, the relationship between Ni and Co is 58- (5/3) Ni <Co≤86.25- (5/2).
Ni, and one or more of Cr 2.5% or less, Mo 3.5% or less, and W 5% or less is Cr + 0.
54Mo + 0.28W ≦ 2.5, with the balance being a composition consisting of Fe excluding impurities, and having a structure having at least two phases of an austenite phase and a martensite phase generated by work-induced transformation. High strength low thermal expansion alloy. 3. The alloy composition according to any one of claims 1 and 2, further comprising B0.02% or less by weight% and Mg.
High-strength, low heat containing at least two phases of an austenite phase and a martensite phase generated by work-induced transformation, containing one or more kinds of 0.02% or less and Ca0.02% or less Expansion alloy. 4. The alloy composition according to claim 1, further comprising V, Ti, Nb, Ta and H in a weight percentage.
High-strength, low thermal expansion characterized by having a structure containing one or more of f and Zr in a total amount of 1% or less and having at least two phases of an austenite phase and a martensite phase generated by work-induced transformation alloy. 5. The alloy composition according to any one of claims 1 to 4, further having a weight percentage of Al 0.2% or less and REM.
A high-strength, low-thermal-expansion alloy containing 0.2% or less of one type or two types and having a structure having at least two phases of an austenite phase and a martensite phase generated by work-induced transformation. 6. The austenite phase is at least 6 of the total.
The structure is set to be 5% or more.
The high-strength low-thermal expansion alloy according to any one of 5 above.