JPH06220585A - High expansion alloy with high electric resistance - Google Patents

Abstract

PURPOSE:To reduce the content of expensive Ni and to obtain an inexpensive alloy material having superior high expansion characteristic. CONSTITUTION:This high expansion alloy has a composition consisting of, by weight, 9.5-19.5% Ni, 2.5-10.4% Mn, and the balance Fe and also has an austenite single phase structure at room temp. Further, thermal expansion coefficient at 30-300 deg.C and electric resistivity at room temp. are regulated to >=20.0X10<-6>/ deg.C and >=0.7muOMEGA.m, respectively. Moreover, it is preferable to regulate the value of X defined by X=1.89X(Mn%)+(Ni%) to 26.5-29.5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inexpensive high-expansion alloy that is incorporated in electric appliances and the like as a temperature sensor and a temperature compensation component.

[0002]

2. Description of the Related Art High-expansion alloys are used as composite members that are bonded to Fe--Ni-based so-called Invar-type low-expansion alloys, ordinary steel, stainless steel, etc. by mechanical pressure welding or welding. For example, by utilizing the bimetal function of a composite member, it is incorporated in electric products and the like as a temperature sensor and a temperature compensation component. As a high-expansion alloy of this kind, a Fe-Ni-Mn high-expansion alloy is a typical material as described in JIS C2530, for example. Fe-Ni-Mn-based high expansion alloy is Fe-36% N
A high-sensitivity bimetal can be obtained by combining it with a low expansion alloy such as i.

Fe-Ni-Mn used conventionally
The high-expansion alloys are generally alloys obtained by adding Mn to a Fe-Ni alloy containing 20 to 22% by weight of Ni. For example, Fe-20% Ni-6% Mn alloy is a bimetal. It is used as a high expansion side material. The main characteristics required for bimetal materials are 30 to 30.
The coefficient of thermal expansion is 0 ° C. and the electrical resistivity at room temperature. For example, the Fe-Ni-Mn high-expansion alloy contains 30 to 300
A material having a coefficient of thermal expansion of 20.0 to 22.0 × 10 ⁻⁶ / ° C. and an electric resistivity of 0.70 to 0.82 μΩ · m at room temperature is required.

[0004]

Problem to be Solved by the Invention Fe-20% Ni-6
The% Mn-based alloy contains a large amount of expensive Ni and thus has a high material cost. Therefore, it is a material that is used for a special purpose commensurate with cost and lacks versatility. This point, F
e Inexpensive high-expansion alloy for bimetal, which has a smaller Ni content than the 20% Ni-6% Mn alloy and has the same thermal expansion characteristics and electrical resistivity as the Fe-20% Ni-6% Mn alloy. Is strongly requested. The present invention was developed to meet such requirements, and by mutually defining the Ni content and the Mn content, high thermal expansion characteristics and electric resistance values can be obtained even if the Ni content is reduced. It is intended to provide the alloys shown.

[0005]

The high expansion alloy of the present invention comprises:
In order to achieve the object, it has a composition of Ni: 9.5 to 19.5% by weight, Mn: 2.5 to 10.4% by weight, and the balance of Fe, and exhibits an austenite single-phase structure at room temperature.
The thermal expansion coefficient in the temperature range of 00 ° C is 20.0 × 10
It is characterized by having an electric resistivity of 0.7 μΩ · m or more at room temperature of ⁻⁶ ° C. or more. Here, X = 1.89 × (%
X value defined by Mn) + (% Ni) is 26.5-2
By making the Ni content and the Mn content have a correlation so as to be in the range of 9.5, the coefficient of thermal expansion is 21.
It is preferably 0 × 10 ⁻⁶ / ° C. or more.

[0006]

The inventors of the present invention have investigated the thermal expansion characteristics and the electrical resistivity of the Fe-Ni-Mn-based alloy in detail, and as a result, have found that the Ni content and Mn so that the structure at room temperature has an austenite single phase.
When the Ni content is strictly controlled, an alloy having a sufficiently large coefficient of thermal expansion and electrical resistivity to be put to practical use even when the Ni content is low was found, and the present invention was completed. Fe-Ni
As is clear from FIG. 1, which shows the relationship between the room temperature structure of the —Mn ternary alloy and the thermal expansion coefficient and the electrical resistivity, it is necessary to use a Ni The lower limits of the content and the Mn content are regulated.
In particular, when the X value represented by the formula (1) is in the range of 26.5 to 29.5, the coefficient of thermal expansion in the temperature range of 30 to 300 ° C. is high, exceeding 21.0 × 10 ⁻⁶ / ° C. Indicates a value. X = 1.89 × (% Mn) + (% Ni) ··· (1)

The X value is obtained from the data shown in FIG. 1 and is an index showing the austenite forming ability of the Fe-Ni-Mn ternary alloy. That is, Mn is 1.8 of Ni.
It has an austenite forming ability equivalent to 9 times. For example, when the Mn content is increased by 1% by weight, the equivalent austenite stability is obtained even when the Ni content is decreased by 1.89% by weight. When the X value is less than 26.5, the austenite + martensite two-phase structure is formed, and when it exceeds 29.5, the austenite phase becomes too stable, and in any case, the thermal expansion coefficient is less than 21.0 × 10 ^-6 / ° C. .

The components and contents of the alloy of the present invention will be described below. Ni: An alloying element necessary for obtaining an austenite single phase structure at room temperature. If the Ni content is too low, an austenite single phase structure cannot be obtained and high expansion characteristics are not exhibited. Further, a Ni content of 9.5% by weight or more is necessary to secure high expansion. However, when a large amount of Ni exceeding 19.4% by weight is contained, not only the effect of increasing the thermal expansion coefficient and the electrical resistivity is saturated, but also an expensive alloy material is obtained. Therefore, in the present invention, the Ni content is specified in the range of 9.5 to 19.4% by weight.

Mn: An alloying element necessary for obtaining an austenite single-phase structure at room temperature, and must be contained in an amount of 2.5% by weight or more. However, M exceeding 10.4% by weight
The n content is difficult to manufacture due to deterioration of refractory during melting and generation of Mn fumes. Therefore, in the present invention, the Mn content is defined in the range of 2.5 to 10.4% by weight. When melting the alloy of the present invention, Fe, Ni, M
C, N, Cu, Mo, Co and the like may be mixed from raw materials such as n. Further, Si and Al may be mixed in from a deoxidizer or the like. These impurity elements may be contained in a small amount as long as they do not adversely affect the formation of austenite single phase structure, high expansion characteristics, high electrical resistivity and the like.

The coefficient of thermal expansion is Fe-for the conventional bimetal.
In order to obtain thermal expansion characteristics equivalent to or higher than those of the Ni-Mn-based high expansion alloy, 20.0 × 10 ^-6 / ° C or higher is required. To obtain higher performance bimetal, 21.0 × 10 ^-6
A thermal expansion coefficient of / ° C or higher is preferred. In addition, the lower limit of the electrical resistivity is set to 0.7 μΩ · m so that the low electrical efficiency generally required for a high expansion alloy for bimetals is satisfied.

[0011]

Example An alloy having the composition shown in Table 1 was melted in a vacuum induction melting furnace to obtain a 12 kg steel ingot. In Table 1, A-1 is a conventional alloy, B1 to B9 are alloys of the present invention, and C1.
~ C4 are comparative alloys.

[Table 1]

The obtained steel ingot was forged, and annealed cold-rolled sheet having a sheet thickness of 1.5 mm was obtained through the steps of hot rolling, annealing, cold rolling and annealing. From the cold rolled plate, a sample for measuring thermal expansion having a width of 5 mm and a length of 50 mm and a sample for measuring electrical resistance having a width of 3 mm and a length of 200 mm were cut out. Further, a test piece having a width of 30 mm and a length of 30 mm was cut out as a structure observation sample. The coefficient of thermal expansion was measured in the temperature range of 30 to 300 ° C. The electrical resistivity was measured at room temperature of 25 ° C. Table 2 shows the respective measurement results.

[Table 2]

Conventional alloy A-1 has an austenite single phase structure at room temperature and has a thermal expansion coefficient α of 21.0 × 10 ^-6 /
The temperature and the electrical resistance ρ were 0.79 μΩ · m. Further, the alloys B-1 to B-9 of the present invention have an austenite single phase structure at room temperature, a coefficient of thermal expansion α of 20.0 × 10 ⁻⁶ / ° C. or more, and an electric resistance ρ of 0.70 μΩ · m or more. And an expensive conventional alloy with a high Ni content, Fe-20% Ni-6% M
It showed the same value as the n alloy. Among them, the X value is 26.5.
B-1, B-2, B-5 and B in the range of
Each alloy of -7 exhibited a high coefficient of thermal expansion of 21.0 × 10 ^-6 / ° C or higher. In contrast, comparative alloys C-1 to C-
No. 7 has a two-phase structure of austenite and martensite at room temperature and has a thermal expansion coefficient α of less than 20.0 × 10 ⁻⁶ / ° C.,
The electrical resistance ρ was less than 0.70 μΩ · m, which was significantly lower than that of the conventional alloy A-1. As is clear from this comparison, in the alloy having the Ni content and the Mn content defined according to the present invention, even though the Ni content is low, the conventional Fe-20% Ni-6% Mn alloy is It can be seen that it is used as a comparable high expansion alloy.

[0014]

As described above, in the present invention, by adjusting the Ni content and the Mn content, Fe-20% Ni- which has been conventionally used as a high expansion alloy.
Fe content is lower than that of a 6% Mn alloy, and Fe-2
High expansion alloys with performance comparable to 0% Ni-6% Mn alloys are obtained. This high expansion alloy is an inexpensive material because it has a low Ni content, and is used in a wide range of fields without being restricted by the cost.

[Brief description of drawings]

FIG. 1 is a room temperature microstructure diagram of a Fe—Ni—Mn-based alloy in which the coefficients of thermal expansion and electrical resistivity are arranged.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Seto 4976 Nomura Minami-cho, Shinnanyo-shi, Yamaguchi Nisshin Steel Co., Ltd.

Claims (2)

[Claims] 1. Ni: 9.5 to 19.5% by weight, Mn:
It has a composition of 2.5 to 10.4% by weight and the balance of Fe, exhibits an austenite single phase structure at room temperature, and has a thermal expansion coefficient of 20.0 × 10 ⁻⁶ / ° C. or more in the temperature range of 30 to 300 ° C. High-expansion alloy with an electrical resistivity of 0.7 μΩ · m or more. 2. Ni: 9.5 to 19.5% by weight, Mn:
2.5 to 10.4% by weight, the balance Fe composition, X =
The X value defined by 1.89 × (% Mn) + (% Ni) is in the range of 26.5 to 29.5, exhibits an austenite single phase structure at room temperature, and has a heat in the temperature range of 30 to 300 ° C. A high expansion alloy having a coefficient of expansion of 21.0 × 10 ⁻⁶ / ° C. or higher and an electric resistivity of 0.7 μΩ · m or higher at room temperature.