KR20070057747A - High strength, low thermal expansion alloy having improved twisting properties and wire of said alloy - Google Patents

Abstract

A high strength low thermal expansion alloy which can maintain high tensile strength, excellent twisting properties and low thermal expansion very stably, and a high strength low thermal expansion alloy wire manufactured using the high strength low thermal expansion alloy are provided. A high strength low thermal expansion alloy having improved twisting properties comprises, by mass percent, 0.1 to 0.4% of C, 0.33 to 2.0% of Si, 2.0% or less of Mn, 3.0% or less of Cr, exceeding 0.5% to 3.0% of V, 25 to 40% of Ni, and the balance of Fe and inevitable impurities, wherein V, C and Cr satisfy the relational expressions 2<=V/C<=9 and 0.9<=V/Cr. The high strength low thermal expansion alloy further comprises 3.02% or less of Co, and Ni and Co satisfy the relational expression 37%<=Ni+Co<=40%. The high strength low thermal expansion alloy further comprises 0.05% or less of B or/and 0.05% or less of Ca. The high strength low thermal expansion alloy further comprises: 0.05% or less of B or/and 0.05% or less of Ca; and 1.20% or less of one or more of Al, Mo, Ti, Nb, Zr, Hf, W, and Cu.

Description

High strength low thermal expansion alloy and alloy wire with improved kink properties {HIGH STRENGTH, LOW THERMAL EXPANSION ALLOY HAVING IMPROVED TWISTING PROPERTIES AND WIRE OF SAID ALLOY}

The present invention relates to high strength low thermal expansion alloys and alloy wires with improved (excellent) twisting properties, for example for use as core material for low-sag transmission lines.

Until now, iron wires have been mainly used as core wires in high-priced transmission lines in the form of twisted wires of heat-resistant aluminum alloys. In addition, in order to cope with the recently increased power demand, an increase in the amount of transmission is required. However, when the amount of power transmission is increased, the existing steel wires have a sagging problem due to the high coefficient of thermal expansion. In order to overcome this problem, an Invar alloy having a low coefficient of thermal expansion has been used as a core material for reducing deflection and thereby increasing the amount of power transmission. In this case, the Invar alloy is finally used as a thin twisted line, so the Invar alloy must have good tensile properties that can be maintained with high tensile strength and high stability.

In view of the above, high-strength low thermal expansion alloys have been proposed in, for example, Japanese Patent Publications 21622/1991 and 21623/1991 and Japanese Patent No. 2968430. In particular, Japanese Patent Publication No. 21622/1991 has a high strength, low carbon consisting of more than 0.1% to less than 0.3%, cobalt: 0.1% to less than 0.5%, and copper: 0.1% to 7.0% or less, cobalt + copper: 0.8% or less Thermal expansion alloys are described, which alloys further comprise nickel + cobalt + copper: an amount that meets the requirements of 38.8% -50.0%, at least 1.0% or less selected from silicon, manganese, and chromium, and molybdenum, titanium At least one selected from vanadium, zirconium, niobium, hafnium, decarburized and tungsten, from 0.20% to 4.0%, with the remainder substantially consisting of iron.

Japanese Patent Publication 21623/1991 contains nickel in an amount that satisfies the requirements of carbon: more than 0.1% and less than 0.3%, copper: 0.1% to 7.0%, nickel + copper: 35.0 to 50.0%, and silicon, manganese and chromium At least one selected from more than 1.0% to 5.0%, and at least one selected from titanium, niobium, vanadium, zirconium, tantalum, tungsten, hafnium, and aluminum, up to 4.5%, the remainder being substantially high-strength low thermal expansion Describe the alloy. Japanese Patent No. 2968430, by weight, carbon: 0.1% to 0.4%, silicon: 0.2% to 1.5%, manganese: 0.1% to 1.5%, nickel: 33% to 42%, cobalt: 5.0% or less, chromium: 0.75 % To 3.0%, vanadium: 0.2% to 3.0%, boron: 0.003% or less, oxygen 0.003% or less, aluminum 0.1% or less, magnesium 0.1% or less, titanium: 0.1% or less, and calcium: 0.1% or less, substantially the rest The high strength, low thermal expansion alloy which consists of iron and an unavoidable impurity, and which satisfy | fills the requirements expressed by the formula of 1.0% <vanadium + chromium <5.0% is described.

On the other hand, conventional high strength alloy wires are described in, for example, Japanese Patent Laid-Open Nos. 279945/1994 and 346193/1994. Japanese Patent Laid-Open No. 279945/1994 describes a high strength low thermal expansion alloy wire having a structure mainly composed of an austenite phase and containing a process-induced martensite phase, wherein the alloy wire is carbon: 0.06 to 0.50% by weight and cobalt. : 65% or less, nickel: 30% or less, cobalt + nickel: 25 to 65%, and the rest mainly made of iron.

Japanese Patent Laid-Open Publication No. 346193/1994 describes a high strength low thermal expansion alloy wire having at least two phases of an austenite phase and a martensite phase formed by a process induced transformation, wherein the alloy wire is carbon: 0.06 to 0.05% by weight. , Silicon: 1% or less, manganese: 2% or less, nickel: 25-30%, cobalt: 2-16.3%, and 52- (5/3) nickel ≤cobalt≤58- (5/3) nickel It satisfies the requirements expressed by the formula, and consists of 1% or less or 1% or less in total of 2 kinds selected from vanadium, titanium, niobium, tantalum, hafnium, and zirconium and inevitable impurities.

In the above conventional techniques described in Japanese Patent Publications 21622/1991 and 21623/1991, vanadium may be added as one of a plurality of reinforcing elements as necessary. However, the superiority of vanadium addition over the addition of other elements with respect to the kink properties is not particularly described. Japanese Patent 2968430 describes the superiority of vanadium addition over the addition of other elements with regard to the kink properties. However, the alloys described in this patent are still insufficient to maintain very stable both high tensile strength, good twisting properties, and low thermal expansion when used as core material for low deflection transmission lines.

The conventional techniques described in Japanese Patent Laid-Open Nos. 279945/1994 and 346193/1994 use a process induced martensite transformation. However, alloy wires produced using the materials described in these publications include the high cost problem of about 10% cobalt present. In addition, in these materials, although the tensile strength is improved by the induction of martensite transformation, the coefficient of thermal expansion increases, and as a result, the twisting property is disadvantageously deteriorated.

The present inventors have conducted extensive and intensive studies to solve the above problems of the prior art, and as a result, control of the content ratio of carbon and vanadium (V / C; vanadium / carbon) as an aging reinforcing element, and containing chromium It has been found that the above problems of the prior art can be solved by adjusting the ratio of V / Cr (vanadium / chromium).

Accordingly, it is an object of the present invention to provide a high strength low thermal expansion alloy having properties that can be maintained very stably, such as high tensile strength, excellent twisting properties and low thermal expansion.

It is yet another object of the present invention to provide a high strength, low thermal expansion alloy wire using vanadium-containing iron-nickel-based alloy, the wire having a tensile strength of at least 1300 MPa, preferably at least 1400 MPa, and excellent twisting properties, namely 20 times / 100D or more, preferably 60 times / 100D or more.

The present invention is summarized as follows.

(1) On a mass basis,

Carbon: 0.1 ~ 0.4%

Vanadium: greater than 0.5 to 3.0%, and

Nickel: Contains 25-50%

Satisfies the requirements expressed by the formula 2 ≦ vanadium / carbon ≦ 9,

High strength low thermal expansion alloy with improved kink properties, consisting of the remaining iron and inevitable impurities.

(2) the alloy according to item (1), further comprising at least one selected from the group consisting of silicon: 2.0% or less, manganese: 2.0% or less, chromium: 3.0% or less and cobalt: 10% or less on a mass basis; High strength low thermal expansion alloy made.

(3) An alloy according to item (1) or (2), wherein 0.5 ≤ vanadium / chromium.

(4) The high strength low thermal expansion alloy, wherein the alloy according to any one of (1) to (3) is 37 mass%? Nickel + cobalt? 40 mass%.

(5) at least one selected from the group consisting of boron: 0.05% or less, calcium 0.05% or less, and magnesium: 0.05% or less by weight based on the alloy according to any one of (1) to (4) above High strength low thermal expansion alloy further comprising.

(6) an alloy according to any one of (1) to (5), wherein, on a mass basis, at least one selected from the group consisting of aluminum, molybdenum, titanium, niobium, tantalum, zirconium, hafnium, tungsten, and copper; High strength low thermal expansion alloy further comprising one or less in total 5% by mass.

(7) A high strength low thermal expansion alloy wire having improved braiding properties, manufactured using the high strength, low thermal expansion alloy according to any one of (1) to (6) above.

(8) a high strength low thermal expansion prepared by using the high strength low thermal expansion alloy according to any one of the items (1) to (6) and having improved twisting characteristics of tensile strength of 1300 MPa or more and twist value of 20 times / 100 D or more Alloy wire. Where D is the final linear diameter.

(9) A high strength low thermal expansion alloy wire having improved twisting properties with an elongation of at least 0.8% according to item (7) or (8) above.

The average linear expansion coefficient between the following 6 / ℃ and (15 to 100 ℃), two points at a temperature of 15 to 230 ℃ range ^- 10 15 - average coefficient of linear expansion is 3 × 10 between two points at a temperature of 100 ℃ range Is 4 × 10 ^-6 / ℃ or less (15 to 230 ° C), and the average coefficient of linear expansion between two points at temperatures in the range of 100 to 240 ° C is 4 × 10 ^-6 / ℃ or less (100 to 240 ° C), 230 Improved according to any one of items (7) to (9) above, which satisfies the characteristic requirement that the mean coefficient of linear expansion between two points at temperatures in the range of 290 占 폚 is below 11 x 10 ^-6 / 占 폚 (230-290 占 폚) High strength low thermal expansion alloy wire with twisting properties.

(11) A high strength, thermally expandable alloy wire having improved twisting properties, either aluminum coated or galvanized according to any one of items (7) to (10) above.

Of the present invention Embodiment

Reasons for limiting the chemical composition of high strength, low thermal expansion alloys with improved kink properties according to the present invention will be described. In the following, the expression "%" in the component ratio of the alloy is% by mass unless otherwise indicated.

Carbon: 0.1 ~ 0.4%

Carbon is an element necessary to strengthen materials through solid solution strengthening and carbide precipitation strengthening. However, if the carbon content is exceeded, the twisting property is deteriorated and the coefficient of linear expansion increases. Therefore, the carbon content is limited to 0.1 to 0.4%.

Vanadium: greater than 0.5% to 3.0%

Vanadium is an element necessary to strengthen the material through precipitation strengthening of carbides. Vanadium also inhibits interparticle precipitation of coarse carbides and promotes precipitation of carbides in fine particles. Therefore, vanadium is suitable for improving the twisting property. However, if the content of vanadium is exceeded, the twisting property is deteriorated and the coefficient of linear expansion increases. Therefore, the vanadium content is limited to more than 0.5 to 3.0%.

Nickel: 25-50%

Nickel is essential to realize low thermal expansion, and the content of nickel is limited to 25-50%.

2 ≤ vanadium / carbon (V / C) ≤ 9

V / C is the biggest feature of the present invention. If the vanadium content is extremely low compared to the carbon content, precipitation strengthening is insufficient. Also in this case, the amount of carbon in the solid solution increases and the coefficient of linear expansion increases. In addition, if the vanadium content is extremely large compared to the carbon content, the coefficient of linear expansion increases and further the twisting property is degraded. Thus, the V / C ratio is limited to 2 ≦ V / C / ≦ 9, preferably 3 ≦ V / C ≦ 5.

Silicone: 2.0% or less

Silicone is needed to reinforce the material. However, adding a large amount of silicon increases the coefficient of linear expansion. Therefore, the upper limit of the silicon content is limited to 2.0%.

Manganese: 2.0% or less

Manganese is a deoxidizer and is used to further strengthen the material. However, adding a large amount of manganese increases the coefficient of linear expansion. Therefore, the upper limit of manganese content is limited to 2.0%.

Chromium: 3.0% or less

Chromium is useful for reinforcing materials. However, the addition of large amounts of chromium increases the coefficient of linear expansion. Therefore, the upper limit of the chromium content is limited to 3.0%.

0.5 ≤ vanadium / chromium (V / Cr)

With respect to V / Cr, too much chromium content compared to the content of vanadium results in the formation of crude chromium-based carbides and crude vanadium-chromium-based composite carbides, resulting in deterioration of the kink properties. The V / Cr ratio is preferably 0.5 ≦ V / Cr, more preferably 0.9 ≦ V / Cr.

Cobalt: 10% or less

Cobalt is often contained as an inevitable impurity in raw materials. When intentionally added, cobalt is useful to reduce the coefficient of linear expansion with nickel. However, the addition of large amounts of cobalt increases the cost. Therefore, the upper limit of the cobalt content is limited to 10%.

37% ≤ nickel (Ni) + cobalt (Co) ≤40%

If the material is used as a core material for low deflection transmission lines, the material should have an average low coefficient of linear expansion throughout the temperature range from room temperature to about 300 ° C. Therefore, the total content of nickel and cobalt is limited to 37% ≦ Ni + Co ≦ 40%. If necessary, the total content of nickel and cobalt is 37.5% ≦ Ni + Co ≦ 39%.

Boron: 0.05% or less

Boron is useful for improving hot workability. However, the addition of a large amount of boron deteriorates toughness. Therefore, the upper limit of the boron content is 0.05%.

Calcium: 0.05% or less, and magnesium: 0.05% or less

Calcium and magnesium are elements that act to fix impurities such as sulfur to improve the toughness of the material. However, the addition of these elements in large amounts deteriorates toughness. Therefore, the upper limit of each of the calcium content and the magnesium content is 0.05%.

One or at least two total contents selected from aluminum, molybdenum, titanium, niobium, tantalum, zirconium, hafnium, tungsten, and copper are 5% or less.

Aluminum, molybdenum, titanium, niobium, tantalum, zirconium, hafnium, tungsten, and copper are useful for reinforcing materials. However, the addition of these elements in large amounts deteriorates the ductility and thermal expansion properties of the material. Therefore, the upper limit of the total content of these elements is 5% or less.

The high strength low thermal expansion alloy with improved twist properties according to the present invention has a tensile strength of at least 1300 MPa and a twist value of at least 20 times / 100D. If the tensile strength is less than 1300 MPa, the required tension as the wire cannot be supplied, and the deflection cannot be reduced to the desired level without difficulty, that is, it is difficult to increase the capacity. If the twist value is less than 20 times / 100D, the twisting of the line causes the cutting of the line or the like, and thus the reliability as the line is lost. Therefore, high strength low thermal expansion alloy wire should have a tensile strength of 1300 MPa or more and a twist value of 20 times / 100D or more. In addition, the high strength low thermal expansion alloy wire with improved twisting characteristics according to the present invention preferably has an elongation of 0.8% or more. If the elongation is less than 0.8%, the cutting of the wire occurs during the line processing, so the alloy wire is unreliable. For this reason, the elongation rate is limited to 0.8% or more.

In addition, to have improved kink characteristic high strength, low thermal expansion alloy wire is preferred according to the present invention, a linear coefficient of expansion, and 3 have an average linear expansion coefficient between the two points in the temperature range of ^{15 ~ 100 ℃ × 10 -6 /} ℃ Less than (15 to 100 ° C), the average coefficient of linear expansion between two points in the temperature range of 15 to 230 ° C is 4 × 10 ^-6 / ° C or less (15 to 230 ° C), and the temperature range of 100 to 240 ° C The average coefficient of linear expansion between points is 4 × 10 ^-6 / ° C or less (100-240 ° C), and the average coefficient of linear expansion between two points in the temperature range of 230-290 ° C is 11 × 10 ^-6 / ° C or less (230 ~ 290 ° C). When the coefficient of linear expansion is larger than the above range, the desired level of deflection cannot be obtained and capacity increase is impossible.

High strength low thermal expansion alloys with improved kink properties according to the invention preferably have a corrosion resistant cover on the alloy surface. The lid is preferably aluminum coated or galvanized in terms of productivity. However, other covers with the same level of corrosion resistance can also be used.

 The high strength low thermal expansion alloy with improved kink properties according to the invention is preferably produced as follows. After the casting and rolling is completed, cold processing is performed at a cross-sectional reduction rate of 30 to 90% and heat treatment in a temperature range of 450 to 750 ° C is sequentially performed, followed by cold processing at a reduction ratio of 30 to 99%. The reason why the cold working is performed at a cross-sectional reduction rate of 30 to 90% after the rolling is completed is that effective precipitation strengthening can be carried out when heat treatment is performed at an appropriate temperature in the presence of deformation by cold working. When the section reduction rate is less than 30%, this effect is insufficient, and when the section reduction rate is above 90%, the production cost increases.

Heat treatment after cold working is performed for the purpose of strengthening precipitation and restoring deformation. If the heat treatment temperature is lower than 450 ° C., no effective precipitation strengthening is performed. On the other hand, if the heat treatment temperature exceeds 750 ° C., the strength decreases due to excess aging and recrystallization. The heat treatment produces a scale that degrades the kink characteristics. To remove the scale, a step may be provided after the heat treatment that can achieve the same effect as the peeling step or the peeling step. The reason why the cold working after the heat treatment is performed at a cross-sectional reduction rate of 30 to 99% is because the cold working can provide work hardening. If the cross sectional reduction rate is less than 30%, the intended effect is insufficient, and if the cross sectional reduction rate exceeds 99%, toughness such as twisting property and elongation rate deteriorates.

Example

The following examples illustrate the invention in detail.

The alloy of steel and comparative steels of the present invention containing the elements shown in Table 1 and conventional impurities were produced by a melting process. Then, for steel numbers 1 to 12 and comparative steel numbers 24 to 30 of the present invention, the rod is rolled to a diameter of 12 mm, and the rod is drawn to a diameter of 51%, that is, to 8.4 mm in diameter. (wire drawing). The wires were heat treated at 650 ° C. and then peeled (pilling) to 8.0 mm in diameter. Finally, an alloy wire was manufactured by drawing a section reduction rate of 86%, that is, up to 3.0 mm in diameter. For steel numbers 13 to 23 and comparative steel numbers 31 to 33 of the present invention, the rod was rolled to a diameter of 16 mm, and the rod was drawn to a diameter of 72%, that is, to 8.4 mm in diameter. The wires were heat treated at 580 ° C. and then peeled (pilling) up to 8.0 mm in diameter. Finally, the alloy wire was manufactured by drawing a 92% reduction in section, that is, up to 2.2 mm in diameter.

Tensile strength, elongation, kink and thermal expansion of these materials were investigated. The results are shown in Table 1. Regarding tensile strength and elongation, tensile test pieces of 3.0 or 2.2 mm in diameter and 250 mm in gauge length were used. Regarding the thermal expansion characteristics, specimens with a diameter of 3.0 mm or 2.2 mm x 10 mm in length were heated or cooled by induction heating, and the change in length was measured by a power transformer. For twisting characteristics, it is necessary to fix and cut one end of an alloy wire of 3.0 mm in diameter and 300 mm in length (100 times larger than diameter) or 2.2 mm in diameter and 220 mm in length (100 times larger than diameter). Twist until cutting to count twist counts. The twist value was measured by the number of twists. As a result, as shown in Table 1, the alloy wire according to the present invention had excellent twisting properties, elongation rate and low linear expansion coefficient even when the tensile strength increased to 1300 MPa or more, preferably 1400 MPa or more.

As described above, even when the tensile strength is 1300 MPa or more, preferably 1400 MPa or more, by using the vanadium-containing high strength low thermal expansion alloy according to the present invention, which satisfies the requirement expressed by the formula 2≤Vanadium / Carbon≤9 The alloy wires produced had good twisting properties, that is, a twist of 20 times / 100 D or more, even 100 times 100D or more. In addition, since neither the processing oil nor martensite occur, the alloy wire of the present invention has an excellent effect, that is, the coefficient of linear expansion is low.

Claims (9)

As mass%, C: 0.1-0.4%, Si: 0.33-2.0%, Mn: 2.0% or less, Cr: 3.0% or less, V: greater than 0.5% to 3.0%, and Ni: Including 25-40%, A high strength, low thermal expansion alloy with improved kink properties characterized by meeting the requirements of 2 ≦ V / C ≦ 9 and 0.9 ≦ V / Cr, with the remainder being iron and inevitable impurities. The high-strength low-expansion alloy having excellent kink characteristics according to claim 1, comprising Co: 3.02 mass% or less and 37% ≦ Ni + Co ≦ 40%. The high-strength low thermal expansion alloy having excellent kink characteristics according to claim 1 or 2, comprising one or two of B: 0.05% by mass or less and Ca: 0.05% by mass or less. The compound according to claim 1 or 2, comprising one or two of B: 0.05% by mass or less and Ca: 0.05% by mass or less; And one or two or more of Al, Mo, Ti, Nb, Zr, Hf, W, and Cu in a total amount of 1.20% by mass or less. A high strength low thermal expansion alloy wire having excellent kink characteristics produced using the alloy according to claim 1. Prepared using the alloy according to claim 1 or 2, the tensile strength is 1300 MPa or more, the twist value is 20 times / 100D or more (where D is the final linear diameter), characterized by excellent high strength properties Thermal expansion alloy wire. The high-strength low thermal expansion alloy wire excellent in the twisting property of Claim 6 which has a characteristic that elongation rate is 0.8% or more. The coefficient of linear expansion according to claim 7, wherein the coefficient of linear expansion between the two points in the temperature range of 15 ~ 100 ℃ is 3 × 10 ^-6 / ℃ or less (15 ~ 100 ℃), between the two points in the temperature range of 15 ~ 230 ℃ The average linear expansion coefficient is 4 × 10 ^-6 / ℃ or less (15 ~ 230 ℃), the average linear expansion coefficient between two points in the temperature range of 100 ~ 240 ℃ is 4 × 10 ^-6 / ℃ or less (100 ~ 240 ℃), And high-strength low-expansion alloy wire having excellent twisting characteristics, characterized in that the average linear expansion coefficient between the two points in the 230 ~ 290 ℃ temperature range satisfies 11 × 10 ^-6 / ℃ or less (230 ~ 290 ℃). The high strength low thermal expansion alloy wire of Claim 7 or 8 by which an alloy wire is aluminum-coated or galvanized, and is excellent in twisting characteristics.