JP3030065B2 - High expansion alloy - Google Patents

Description

The present invention relates to inexpensive high expansion alloys, mainly for bimetals.

[Conventional technology and its problems]

The high expansion alloy is composed of a composite member by mechanical pressure welding or welding with Fe-Ni based so-called amber type low expansion alloy, ordinary steel, stainless steel, etc., and uses its bimetal function to make temperature sensors and temperature compensation parts. It is used in large quantities in electrical products and the like.

As described in JIS C2530, an Fe-Ni-Cr alloy is a kind of high expansion alloy and is widely used as a general-purpose material.

However, there is no specific chemical composition, generally, Fe-Ni-based alloys exhibit high expansion characteristics
An alloy obtained by adding Cr to -20 to 22Ni is used. For this reason, Fe-20Ni-5Cr and Fe-22Ni-3Cr are often used as high expansion materials for bimetals.

The main characteristics required for bimetal materials are 30 to 10
The coefficient of thermal expansion at 0 ° C and the electrical resistivity at room temperature. For example, in Fe-20Ni-5Cr, the coefficient of thermal expansion at 30 to 100 ° C. is 18.0.
~ 19.0 × 10 ^-6 / ° C, electrical resistivity at room temperature is 74 ~ 82μΩ ・ c
Materials with m characteristics are required.

Inexpensive, mainly for bimetals, with less Ni content than Fe-20Ni-5Cr or Fe-22Ni-3Cr and having the same thermal expansion characteristics and electrical resistivity as Fe-20Ni-5Cr or Fe-22Ni-3Cr An alloy is desired.

[Knowledge on problem solving]

The present inventors have proposed Fe, in order to solve the above-described problems.
The relationship between the composition, the thermal expansion characteristics, and the electrical resistivity of the Ni-Cr alloy was examined in detail.

As a result, even when the Ni content is low, a composition range having a thermal expansion coefficient as large as that of the conventional materials Fe-20Ni-5Cr and Fe-22Ni-3Cr was found, and at least one of Si and Al was found. It has been found that the electrical resistivity of the Fe-Ni-Cr alloy can be increased by increasing the above content.

[Configuration of the invention]

In the present invention, Ni: 9 to 18% Cr: 4 to 13% C: 0.5% or less Mn: 4% or less C: 0.2% or less Co: 2% or less The balance consists of Fe and unavoidable impurities.
4.0% and Al: at least one of 0.1 to 4.0%, having an austenitic single phase structure at room temperature, 30 to 100%
Provided is an inexpensive high-expansion alloy having a thermal expansion coefficient at 18 ° C. of 18 × 10 ⁻⁶ / ° C. or more and an electrical resistivity at room temperature of 74 μΩ · cm or more.

In order to obtain high expansion characteristics, it is essential to have an austenitic single phase structure at room temperature.

In order to increase the electric resistivity, it is effective to increase the content of Si or Al.

Next, the reasons for limiting the alloy composition in the present invention will be described.

Ni: If the Ni content is too low, high expansion characteristics are not exhibited. To ensure high expansion characteristics, 9% or more is required. However, if the content of Ni is large, the production cost increases, so the upper limit is set to 18%.

Cr: The Fe-9 to 18Ni-Cr alloy according to the present invention needs to be an austenitic single phase at room temperature, but this alloy system tends to generate martensite at room temperature. Cr has an action of suppressing the formation of martensite, and in this sense, the alloy of the present invention requires the addition of 4% or more of Cr. But a lot of Cr
Is 13% or less in order to reduce the expansion coefficient.

C: At room temperature, necessary to obtain austenite single phase structure, but if added in large amounts, it hardens
It was as follows.

Si: Necessary for increasing electric resistivity, its effect can be obtained by adding 0.4% or more. However, excessive addition causes hardening, so it was set to 4.0% or less.

Mn: Necessary for obtaining an austenite single phase structure at room temperature, but 4% or less is sufficient.

N: Necessary for obtaining an austenitic single phase structure at room temperature, but excessive addition causes 0.2% or less of defects during steel making, so it was made 0.2% or less.

Al: It is necessary to increase the electrical resistivity, and its effect can be obtained by adding 0.1% or more. However, excessive addition has an adverse effect on productivity, and is therefore set to 4.0% or less.

Although it is mixed from Co: Ni raw material, the content is not affected, so that the content of 2% or less is allowed.

[Specific disclosure of the invention]

 Next, specific examples will be described.

The 32 alloys shown in Table 1 were melted in a vacuum induction melting furnace.
A 12 kg steel ingot was obtained. Subsequently, the steel ingot was subjected to the steps of forging → hot rolling → annealing → cold rolling → annealing, and then a sample for measuring thermal expansion (1.5 × 5 × 5
0 mm) and a sample for electric resistance measurement (1.5 × 3 × 200 mm).

The coefficient of thermal expansion was measured in a temperature range of 30 to 100 ° C. The electric resistivity was measured at room temperature (about 25 ° C.). The results are shown in Table 1.

FIG. 1 shows the effect of the Si and Al contents on the electrical resistivity of the alloy of the present invention. As shown in the figure, the electric resistivity of the Fe—Ni—Cr alloy can be increased by increasing the content of Si or Al. Invention alloy Fe-15Ni-7C
In r, Fe-15Ni-9Cr and Fe-18Ni-5Cr, an electrical resistivity of 74 μΩ · cm or more can be obtained by containing 0.4% or more of Si and 0.1% or more of Al.

As is clear from Table 1, the properties of the alloys of the present invention are the same as those of the conventional alloys S. No. 20 and S. No. 21, Fe-20Ni-5Cr or Fe.
The value was equivalent to -22Ni-3Cr.

[Effect of the Invention] As described above, the alloy of the present invention has a Ni content of 9 to 18%.
% And a smaller Ni content compared to Fe-20Ni-5Cr or Fe-22Ni-3Cr, and an inexpensive high expansion alloy can be provided.

[Brief description of the drawings]

FIG. 1 is a graph showing the influence of Si and Al contents on the electrical resistivity.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Katsunori Babaen 4976 Tomita, Onan, Shinnanyo-shi, Yamaguchi Pref. JP-A-3-31446 (JP, A) JP-A-53-72720 (JP, A) JP-A-1-171963 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C22C 38 / 00 302

Claims (1)

(57) [Claims] [Claim 1] Ni: 9 to 18% Cr: 4 to 13% C: 0.5% or less Mn: 4% or less N: 0.2% or less Co: 2% or less The balance is composed of Fe and unavoidable impurities. ~
4.0% and Al: at least one of 0.1 to 4.0%, having an austenitic single phase structure at room temperature, 30 to 100%
An inexpensive high-expansion alloy with a thermal expansion coefficient of 18 × 10 ⁻⁶ / ° C. or more at ℃ and an electric resistivity at room temperature of 74 μΩ · cm or more.