JP3216824B2 - High strength low thermal expansion alloy - Google Patents

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 mechanical parts and core wires for heat-resisting transmission lines having a low sag during use.

[0002]

2. Description of the Related Art Conventionally, steel core aluminum stranded wires (ACSR wires) have been used for overhead power transmission lines. However, recent increases in power demand and rising land prices have replaced the conventional steel core aluminum stranded wires. An alloy wire having high strength and low coefficient of thermal expansion has been desired. For such applications,
6-45990, JP-A-55-41928, JP-B-57-17942, JP-A-55-122855, JP-A-55-128565, and JP-A-55-131155.
JP-A-56-142851, JP-A-57-261
No. 44, JP-A-58-11767 and JP-A-58-11867.
No. 11768 and the like are disclosed.
Furthermore, for the purpose of improving the strength and torsion characteristics of these alloys, JP-B-63-56289, JP-B-60-346.
No. 13, JP-A-57-110659, Tokuhei 2-15
606, JP-A-58-77525, JP-A-58-2
10126, JP-A-58-221225, JP-A-5-222
No. 7-41350, Japanese Patent Publication No. 2-41577 and Japanese Patent Publication No. 2-55495 disclose a method for producing a high-strength low-thermal-expansion alloy wire or alloy wire.

[0003]

The above-mentioned conventional high-strength low-thermal-expansion alloys all contain 35% or more of Ni or Ni + Co.
In the range of 50%, C and N interstitial solid solution strengthening elements, and several substitutional solid solution strengthening elements such as Cr and Mo, and T
It has an alloy composition consisting of several kinds of precipitation strengthening elements such as i and Nb in a range not impairing the low thermal expansion characteristics, and the balance being Fe. In any of these alloys, in the solution heat treatment or the annealing heat treatment, good torsion characteristics can be obtained, but the tensile strength is at most 50 to 80 kgf / mm ² , and in this state, low sag overhead It is not suitable for applications of core wires for power transmission lines. However, each of these alloys has a work hardening ability which is larger than that of conventional low thermal expansion alloys of 36% Ni-Fe alloy and 42% Ni-Fe alloy, and is 100 to 130 kgf / mm ² by cold working. Tensile strength was obtained, and some of them became practical. However, the strength of the piano wire used for the conventional steel core aluminum stranded core wire is 1
Those 70 kgf / mm ² class have tighten more, in order to increase the transmission capacity of the transmission line without rebuilding the tower has a 170kgf / mm ² class piano wire about the same tensile strength, A low thermal expansion alloy wire was required.
In addition, the conventional high-strength low-thermal-expansion alloy wire described here simply deteriorates the torsion characteristics by simply applying strong working in the cold range, so that it is necessary to achieve both tensile strength and torsion characteristics. In the above publication, various complicated production methods are proposed. For example, Japanese Patent Publication No. 60-34613 and
In -15606, strain relief annealing is performed in a stage before cold working or in the middle of cold working to try to achieve both strength and torsion characteristics. It is specified in these manufacturing methods that good twisting characteristics can be obtained by removing surface distortion caused by peeling by annealing heat treatment.

On the other hand, the alloy wire disclosed in Japanese Patent Publication No. 2-41577 and Japanese Patent Publication No. 2-55495 uses almost the same manufacturing process as the above-mentioned Japanese Patent Publication No. 60-34613 and Japanese Patent Publication No. 2-15606. However, it is described herein that Mo ₂ C carbide generated during annealing after cold working contributes to improvement in strength and torsion characteristics. However, Tokuhei 2
One of the inventors of U.S. Patent No. 41577 and Japanese Patent Publication No. 2-55495 is "Effect of processes o
f drawing on tortional pr
goodness of high-tensilest
length Invar alloy wire "
(Wire Journal International
al vol. 21, No. 4 (1988), P84)
The improvement of the torsion characteristics. In this paper, the improvement of the torsion characteristics is not sufficient only by performing an annealing heat treatment for precipitating Mo ₂ C carbides after cold working. In particular, in the hardness distribution of the cross section of the alloy wire after drawing, the hardness distribution at the center is not sufficient. It is reported that a special jig called a Christopherson tube for reducing the die withdrawal angle and improving lubricity so as to maximize the hardness is required. However, increasing the torsion characteristics by using a special jig called a Christopherson tube for reducing the die pulling angle or improving lubricity increases the number of drawing passes (the pulling angle becomes smaller). In other words, it is impossible to increase the reduction in area per pass), and it takes time to change the process of the line, and it is a very inefficient manufacturing method for manufacturing alloy wires having a total length of several kilometers. is there. In view of the above problems, the present invention has a higher rank than conventional Fe-Ni-based high-strength low-thermal-expansion alloys, that is, has a tensile strength comparable to that of a piano wire, and is stable without a complicated process. And to provide a high-strength low-thermal-expansion alloy having high torsion characteristics.

[0005]

Means for Solving the Problems The present inventors have proposed Fe-C
Using a hot-rolled material having an alloy composition in which various alloying elements were added to an o-Ni-based alloy, the tensile properties, torsion properties and thermal expansion coefficient of the alloy wire were investigated. As a result, the conventional austenite phase is stable Fe-
It has been found that a Ni-based high-strength low-thermal-expansion alloy cannot provide high strength comparable to a piano wire. Therefore, in order to obtain a high strength at a level intended by the present invention, an alloy composition in which a part of the austenite phase is transformed into a martensite phase by the cold working of the strength is selected, and further, before the cold working at that time, It has been found that by optimizing the composition of the alloy to obtain the lowest coefficient of thermal expansion, it is possible to achieve both high strength and low thermal expansion characteristics. Furthermore, for applications of core wires for low sag heat-resistant transmission lines, the alloy of the present invention requires no complicated intermediate annealing step in the normal cold drawing step after stripping, and simple cold drawing. It has been clarified that the twisting value and the stabilization of the twisting value are the same level as those of the conventional piano wire only by performing the process, and it has been found that it is particularly suitable as a core wire for power transmission lines. Such an alloy composition region is referred to as 54Co-9 called stainless invar.
An alloy of Cr-remainder Fe and super invar 3
It is located in a region (FIG. 1) in which the alloy of 1Ni-6Co-balance Fe is made in a proportionate relationship with an alloy having a composition in which the austenite phase is more unstable. It has been found that by adding an appropriate amount of C which greatly contributes to the above, an alloy having a desired level can be obtained.

That is, in the high twist high strength low thermal expansion alloy wire of the present invention, the first invention has a C content of 0.06-0.
50%, Si 0.5% or less, Mn 1.5% or less, Ni2
5-30%, Co2-16.3%, and the relationship between Ni and Co is 52- (5/3) Ni ≦ Co ≦ 58- (5
/ 3) The composition is composed of Ni and the remainder is composed of Fe excluding impurities, and is substantially composed of an austenite phase and a martensite phase.
And a metal structure consisting of two phases
The martensitic phase is at least 65%,
A high-strength low-thermal-expansion alloy characterized by having a metal structure containing a martensite phase generated by work-inducing . The second invention is a 0.02 to 0.50% by weight C, Si
0.5% or less, Mn 1.5% or less, Ni 30% or less, C
o-58%, one or two of Cr 10% or less and Mo 3% or less, and the relationship between Ni and Co is 52- (5
/ 3) Ni ≦ Co ≦ 58− (5/3) Ni and the relationship between Ni and (Cr + Mo) is 5- (1/5) Ni ≦ (Cr +
Mo) .ltoreq.10- (1/5) Ni, the balance being Fe excluding impurities, substantially austenitic phase
And a martensitic phase.
The austenitic phase in the metallic structure is 65% or more,
The martensite phase is a martensite produced by process induction.
A high-strength low-thermal-expansion alloy characterized by having a metal structure containing a G phase.
0.50%, Si 0.5% or less, Mn 1.5% or less, C
o 52-58%, Cr 10% or less or Mo3
% Or less, and the remainder is F
e, consisting essentially of an austenitic phase and
Metal structure consisting of two phases
The austenite phase in the weave is 65% or more;
Theite phase contains a martensitic phase generated by processing induction.
This is a high-strength low-thermal-expansion alloy characterized by having a metal structure .

In a fourth aspect of the present invention, the alloy composition further comprises, in addition to the alloy composition of any one of the first to third aspects, further comprising:
0.02% or less, Mg 0.02% or less and Ca0.0
Contains 1% or less of 2% or less and is substantially aus
Metal structure consisting of two phases, tenite phase and martensite phase
And the austenite phase in the metal structure is 65% or less.
In addition, the martensite phase is formed by
High strength low thermal expansion alloy is characterized in that a metal structure containing martensite phase.

[0008]

The reasons for limiting the components in the chemical composition range of the high-strength low-thermal-expansion alloy of the present invention will be described below. C is an element that most contributes to the work hardening of the austenite phase during cold working and the improvement of the strength of work-induced martensite in the alloy of the present invention. Further, a part of Ni or Co can be substituted as an austenite stabilizing element. In order to obtain such an effect, when C contains Cr or Mo, at least 0.02% or more, and when both C and Mo are not contained, the work hardenability of the alloy is lowered and the austenite phase is destabilized. Requires at least 0.06%, but conversely 0.50%
% Of C excessively stabilizes the austenite phase and makes it difficult to cause martensitic transformation.
This leads to an increase in the coefficient of thermal expansion. Therefore, the C content is limited to 0.02 to 0.50% when Cr or Mo is included, and 0.06 to 0.50% when neither Cr nor Mo is included. It is known that any region connecting the alloy composition of stainless steel Invar and the alloy composition of Super Invar with a straight line shows invar properties, but without the addition of C, the strength and low thermal expansion properties intended by the present invention are obtained. One of the major features of the present invention is that an appropriate amount of C is added to such an alloy composition region in terms of composition. A more desirable range of C is 0.10 to 0.30%.

[0009] Si and Mn are contained in the alloy of the present invention as deoxidizing elements. However, excessive amounts of Si and Mn cause an increase in the coefficient of thermal expansion. Therefore, the contents are limited to 0.5% or less and 1.5% or less, respectively. Ni, Co and (Cr + Mo)
In the alloy of the present invention, is an element indispensable for giving Invar characteristics to the alloy together with Fe constituting the balance. In the present invention, 3% or less of Mo can be replaced with an equal amount of Cr as described later. The component ranges of Ni, Co, and (Cr + Mo) can achieve both low thermal expansion characteristics and high strength only within a range that satisfies the mutual relationship in the hatched portion in FIG. When the alloy composition in the region A at the upper right of the hatched portion becomes stable, the austenite phase becomes stable even when a strong cold work is applied, and by selecting the optimum composition in the region A, the coefficient of thermal expansion is sufficiently reduced. Can be produced but the tensile strength is at most 1
At about 30 kgf / mm ² , no further work hardening can be expected. On the other hand, in the region B at the lower left of the shaded portion, the austenite phase can no longer exist stably at room temperature before the cold working, and the low thermal expansion characteristic is lost because the martensite phase is generated. Therefore, the Ni, Co
And the amount of (Cr + Mo) was 30% as shown in FIG.
The following Ni, 2-58% Co, and 10% or less Cr
And 3% or less of Mo, and is limited to a range satisfying the following relationship between Ni and Co and the relationship between Ni and (Cr + Mo). This region represents the second invention. 52- (5/3) Ni≤Co≤58- (5/3) Ni (1) 5- (1/5) Ni≤ (Cr + Mo) ≤10- (1/5) Ni ... ( 2) Here, in both equations, it is assumed that Ni = 0 and (Cr + Mo) = 0 do not occur at the same time.

In particular, when (Cr + Mo) is 0%, the work hardening ability of the matrix decreases and the austenite phase becomes unstable, so the lower limit of C must be 0.06% or more. N
By substituting (Cr + Mo) = 0 in the equation (2), 25 ≦ Ni is obtained. In this case, Ni is substituted into the equation (1) from the relationship of 30% or less. Then, 2 ≦ Co ≦ 16.3 is obtained, and the region of Ni and Co indicates the first invention. Also, when Ni = O is substituted into the equations (1) and (2), 52 ≦ Co ≦ 58 and 5 ≦ Cr + Mo, respectively.
≦ 10, which means the first invention. Further, as for Cr, in order to impart corrosion resistance to the Invar alloy, particularly in the region of high Co-high Cr, good corrosion resistance can be obtained, so that it is quite thick like the conventional Fe-Ni-based high-strength low-thermal-expansion alloy wire. Al coating or Zn plating is unnecessary or the coating thickness can be greatly reduced, which helps to reduce the weight of the transmission line. Mo is Cr
An element belonging to the same genus as Cr and having the same effect as Cr,
Can be replaced by an equivalent amount by weight in the shaded region of FIG. However, when the replacement amount exceeds 3.0%, the precipitation amount of Mo ₂ C carbide becomes too large, and the strength,
Mo is disadvantageous in terms of the coefficient of thermal expansion and the torsion characteristics.
Is 3.0% or less, and 5- (1/5) Ni ≦ Cr
+ Mo ≦ 10− (1/5) Ni.

B segregates at the austenite crystal grain boundaries to strengthen the grain boundaries, and is useful for improving the hot workability and ductility at room temperature of the alloy of the present invention. Also, Mg and Ca combine with S to form granular sulfides, and like B, help to improve hot workability and ductility at room temperature. For such an effect,
One, two or more of B, Mg and Ca can be added simultaneously, but excessive addition of more than 0.02% lowers the melting point of the alloy and conversely lowers the hot workability. Therefore, B, Mg and Ca are all added in an amount of 0.02% or less. Various additional elements for strengthening the Fe-Ni-Co-based alloy can be considered in addition to the above-mentioned C, Cr and Mo, but elements such as Ti, Nb, Ta, Hf and Zr are C
Has a strong affinity with the alloy, generates a hard primary carbide in a lump, easily forms defects during cold working, causes a reduction in tensile elongation and a variation in torsion value. Addition is not preferred. Therefore, each of these elements limits the upper limit to 0.2% or less.

Further, since gas components such as O and N form inclusions in the alloy and similarly cause variation in the twist value, each of the alloy wires of the present invention is limited to 0.01% or less. . In addition, elements such as Al and REM added for the purpose of deoxidation and desulfurization, which are usually contained in the following amounts, may have no problem in properties. Al, REM ≦ 0.1% The alloy according to the present invention is a high-strength low-thermal-expansion alloy composed of the above-mentioned alloy elements and the balance Fe. Next, in the fifth invention alloy of the present application, the amount of austenite is set to 65% or more. If the amount of austenite is less than 65%, the coefficient of thermal expansion increases, and the low thermal expansion characteristic of the present invention decreases.

In the alloy of the present invention having the above composition, the austenite phase is stable at room temperature even after quenching after hot working or solution heat treatment. However, by sufficiently performing cold working, a martensitic transformation occurs due to a work-induced transformation. Work hardening by cold working has a large effect on martensitic transformation, in addition to an increase in work hardening ability of austenite matrix by addition of C, and particularly high Co and high (Cr +
The intensity in the Mo) region is at a level comparable to a piano wire. Further, when the alloy of the present invention is processed into a wire, a stable torsion value of about 40 times can be obtained without performing an annealing treatment particularly in an intermediate step of cold drawing. The torsion value at this level is equivalent to the level of the torsion value of a conventional piano wire, which is based on the work-induced martensite phase already existing by cold working or the austenite phase that occurs during twisting. It is presumed that the effect of the relaxation of the stress due to the transformation into the phase is large. If the austenitic phase is stable even when the matrix of the Invar alloy is subjected to a strong cold working, the coefficient of thermal expansion is low but the tensile strength is insufficient, or when the wire is cold worked, a simple cold working is performed. In the thinning process, the torsion characteristics may be insufficient. Conversely, if the austenite phase becomes too unstable, martensitic transformation occurs in the cooling process after hot working or after solution treatment, and it is no longer possible to obtain invar characteristics. For the reasons described above, in order for the alloy of the present invention to simultaneously obtain high strength, a low coefficient of thermal expansion, and a high torsion value,
It is necessary to have two phases, that is, an austenite phase and a martensite phase generated by the process-induced transformation.

The reverse transformation temperature of such work-induced martensite to austenite is a temperature of 550 ° C. or more, and continuous use at about 300 ° C., which is the highest temperature used as a power transmission line, is a characteristic of the alloy of the present invention. Above, there is no problem. Further, the work-induced martensite is used in the intermediate and finish production steps when used as a transmission line, such as in the case of Al coating treatment or Zn plating treatment.
Although a part of the alloy may be decomposed into carbide and ferrite by heating at ° C., the presence of a small amount of ferrite in the alloy of the present invention does not cause any problem in characteristics.

[0015]

EXAMPLES The composition of Fe-Co- @ Ni- (C
r + Mo)｝ alloy is melted and hot forged with a diameter of 1
Finished into a 3.0 mm round bar. After that, the solution was kept at 980 ° C. for 30 minutes, and then subjected to a solution treatment of water cooling and peeling of the surface.
2.3 mm. Further, using this sample, the coefficient of thermal expansion was measured, and a coil having a workability of 86% and a diameter of 4.6 mm was produced by cold drawing. For cold drawing, a very common WC die with an approach angle of 12 ° is used.
Wire was drawn at a reduction in area of about 20% per pass. The drawing speed at that time was the same speed as the drawing speed of a normal steel wire. Using these wires, a tensile test, a torsion test, a thermal expansion test, a winding / unwinding test, and a measurement of the amount of austenite in the alloy were performed in the state of final processing. Table 2 shows the results.

The elongation in the tensile test was measured at a point of 250 mm between the gauge points, and the average value of the tensile strength and the drawing was determined for each of the five specimens. In the torsion test, the distance between the grips was set to 100 times the self-diameter, and the torsion value until breaking at a rotation speed of 60 rpm was 1 for each.
Zero measurements were made to determine the average value. Regarding the winding / unwinding test, it was examined whether or not the test piece would break when wound and unwound eight times each on a core wire 1.5 times its own diameter. Further, for some samples, X-ray diffraction of the sample cross section was performed,
The amount of austenite was determined by the following equation. Austenite phase (%) = { _Iγ / ( _Iγ + _Iα )} ×
_{100 I γ = I γ (111} ) + I γ (200) + I γ (220) + I γ (311) I γ (111) , etc. X-ray diffraction intensity of austenite _{I α = I α (110)} + I α (200) + I _{α (220)} + I _{α (211)} I _{α (110)} is the X-ray diffraction intensity of martensite

[0017]

[Table 1]

Of the alloys shown in Table 1, Nos. 1 to 16 are alloys of the present invention, Nos. 21 to 25 are comparative alloys, and No. 31 is
This is a high-strength low-thermal-expansion alloy disclosed in JP-A-3-115543. The relationship between Ni and Co or Ni and Cr (+ Mo) of Nos. 1 to 25 is also shown in FIG. Table 2 shows that the alloy of the present invention was 14% after 86% cold working.
It has a tensile strength of 5 to 200 kgf / mm ^{2 and} a coefficient of thermal expansion of 6.0 × 10−6 / ° C. or less.
It can be seen that a coefficient of thermal expansion of 2 or less can be obtained (coefficient of thermal expansion of piano wire α _{30-230 ° C.} ≒ 11.5-13 × 10 minus 6 / ° C.). These properties are slightly inferior in the coefficient of thermal expansion as compared with the conventional high-strength Fe-Ni-based low-thermal-expansion alloy, for example, conventional alloy No. 31, but there is a marked difference in tensile strength. In order to replace the transmission line without rebuilding the existing tower, it is absolutely necessary to have the same strength as the piano wire, so in terms of sag, the conventional Fe-N
Although it is inferior to the i-type high-strength low-thermal-expansion alloy wire, it can be seen that the strength is far higher than that of the conventional Fe-Ni-based high-strength low-thermal-expansion alloy wire. Further, among the alloys of the present invention, B, M
Nos. 4, 12 to which neither g nor Ca was added
14 and 16 have smaller tensile drawing values than the other alloys of the present invention, but this is largely due to the presence or absence of these trace elements.

[0019]

[Table 2]

Further, from Table 2, it can be seen that the alloy of the present invention has a high twist value and excellent winding / unwinding characteristics. Such an effect is brought about by the transformation from the austenitic phase which occurs during the plastic deformation of the work-induced martensite and the various tests present during the cold working to the martensite phase. From Table 2, the alloys of the present invention Nos. 2, 5, 9,
It can be seen that 11, 14, and 15 consist of 68-88% of austenite phase and about 12-32% of martensite phase (more precisely, small amounts of Mo and C carbides are also present). Usually, the austenitic stable type Invar alloy has a lower coefficient of thermal expansion due to cold working, but the alloy of the present invention has a higher coefficient of thermal expansion in the state after cold working than before cold working. Therefore, No.2,5,9,
All of the alloys of the present invention other than 11, 14, and 15 are considered to have undergone work-induced transformation by cold working.

On the other hand, when C is lower than that of the alloy of the present invention as in Comparative Alloy No. 21, or when C is lower as in No. 22
When o is lower than that of the alloy of the present invention and belongs to the region B of FIG. 1, the austenite phase can no longer exist stably at room temperature, and undergoes martensitic transformation to increase the coefficient of thermal expansion (No. At .21 the amount of austenite is only 3%). Conversely, when the Cr or Co is too high as in Comparative Alloy Nos. 23 and 24, and either of them belongs to the region A in FIG. 1, the austenite phase becomes too stable (No. 23, 24). No work-induced transformation occurs in the 100% austenite phase), and the coefficient of thermal expansion is
Like conventional alloy No. 31, it is lowered by cold working,
The tensile strength becomes inferior to the alloy of the present invention. Further, the comparative alloy Nos. 23 and 24 and the conventional alloy No. 31 have a low torsion value of 10 times or less if simply cold-worked after peeling. Becomes unsuitable. Comparative alloy No. 25 has a composition in which Ni and Co satisfy the range of the first invention alloy of the present application, but do not contain (Cr + Mo) and C is 0.04%. In the case of this alloy, even if Cr or C that contributes to work hardening is not added or is added in a small amount, the coefficient of thermal expansion increases by cold working, the torsion value is high, and the amount of austenite is 60%. Indeed, work-induced martensitic transformation has occurred, but the strength is not so high, and although the amount of C is almost the same as that of the alloy No. 6 of the present invention but does not contain Cr, both of them have:
There is a big difference in strength.

[0022]

As described above, the alloy of the present invention is one rank higher than that of the conventional low thermal expansion alloy, that is, has a tensile strength equivalent to or close to that of a piano wire, and is as stable as a piano wire even in a simple manufacturing process. It has a high torsion value and has a low coefficient of thermal expansion less than half that of a piano wire.
The alloy of the present invention makes it possible to manufacture a low sag transmission line that is excellent in reliability and has a higher transmission capacity than a transmission line using a conventional piano wire as a core wire, and therefore can relatively easily increase the transmission capacity of the transmission line. Becomes possible.

[Brief description of the drawings]

FIG. 1 is a diagram in which respective chemical components of an alloy of the present invention and a comparative alloy are plotted.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C22C 38/00 302 C22C 38/08

Claims (4)

(57) [Claims] C. 0.06 to 0.50% by weight, S
i 0.5% or less, Mn 1.5% or less, Ni 25 to 30
%, Co2 to 16.3%, and the relationship between Ni and Co is 52- (5/3) Ni ≦ Co ≦ 58- (5/3) N
i, and the balance is Fe, excluding impurities.
Substantially two phases of austenite and martensite
Austenitic metal structure
G phase is 65% or more, and the martensite phase
A high-strength low-thermal-expansion alloy characterized by having a metal structure containing a martensitic phase generated thereby. 2. 0.02 to 0.50% by weight of C,
i 0.5% or less, Mn 1.5% or less, Ni 30% or less,
Co2 to 58%, one or two of Cr 10% or less and Mo 3% or less, and the relationship between Ni and Co is 52-
(5/3) Ni ≦ Co ≦ 58− (5/3) Ni and N
The relationship between i and (Cr + Mo) is 5- (1/5) Ni ≦ (C
r + Mo) ≦ 10− (1/5) Ni, and the remainder is composed of Fe excluding impurities, and is substantially austenitic.
Metal structure consisting of two phases,
And the austenite phase in the metal structure is 65% or more,
The martensitic phase is formed by the process
A high-strength low-thermal-expansion alloy characterized by having a metal structure containing an incite phase . C. 0.02 to 0.50% by weight, S
i 0.5% or less, Mn 1.5% or less, Co 52 to 58
%, 10% or less of Cr or 3% or less of Mo in total, and the remainder is composed of Fe excluding impurities, substantially consisting of an austenite phase and a martensite phase.
Metal structure consisting of two phases
The martensite phase is processed by 65% or more of the tenite phase
A high-strength low-thermal-expansion alloy characterized by having a metal structure containing a martensite phase generated by induction . 4. The alloy according to claim 1, wherein said alloy composition further comprises, by weight%, B 0.02% or less,
It comprises one or more of the following and Ca0.02% 0.02% substantially austenitic phase and martensite
Metal structure consisting of two phases, site phase and metal structure
65% or more of the austenite phase in
The g phase contains a martensitic phase generated by processing induction
A high-strength low-thermal-expansion alloy characterized by having a metal structure .