JP2961697B2 - High expansion alloy - Google Patents

Description

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

[Conventional technology and its problems]

High-expansion alloy is composed of a composite member by mechanical pressure welding or welding with Fe-Ni-based invar-type low-expansion alloy, ordinary steel, stainless steel, etc., and uses its bimetal function to provide temperature sensors and temperature compensation. It is used in large quantities in electrical products and other parts.

As described in JIS C 2530, Fe-Ni-Cr alloys are a kind of high expansion alloys and are widely used as general-purpose materials.

However, there is no specific chemical composition specified, and generally, a Fe—Ni-based alloy exhibits high expansion characteristics.
An alloy in which Cr is added to Fe-20 to 22Ni is used. For this reason, Fe-20Ni-5Cr and Fe-22Ni-3Cr are often used as high expansion alloys 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.

Inexpensive mainly for bimetal with lower Ni content than Fe-20Ni-5Cr or Fe-22Ni-3Cr steel and having the same thermal expansion characteristics and electrical resistivity as Fe-20Ni-5Cr steel or Fe-22Ni-3Cr steel Are desired.

[Knowledge on problem solving]

The present inventors have proposed Fe, in order to solve the above-described problems.
A detailed study of the relationship between the composition, thermal expansion characteristics, and electrical resistivity of Ni-Cr alloys revealed that
-22Ni-3Cr and Fe-20Ni-5Cr alloys with the same coefficient of thermal expansion as conventional materials and a sufficiently high electrical resistivity to be practically used, even when the Ni content is considerably lower. Was found.

[Configuration of the invention]

The present invention is composed of Ni: 9 to 14% Cr: 5 to 13% C: 0.5% or less Si: 1% or less Mn: 4% or less C: 0.2% or less Co: 2% or less The balance consists of Fe and unavoidable impurities. With an austenitic single phase structure and a thermal expansion coefficient of 18
× 10 ^-6 / ° C or higher and electrical resistivity at room temperature is 70μΩcm
An inexpensive high expansion alloy as described above is provided.

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

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 14%.

Cr: The alloy of the present invention needs to have an austenitic single phase structure, but in the alloy system of the present invention, martensite tends to occur at room temperature, and in this system, Cr has an action of suppressing the formation of martensite, In this sense, it is necessary to add Cr of 6% or more. However, the addition of a large amount of Cr is set to 13% or less in order to lower the coefficient of thermal expansion.

C: Necessary for obtaining an austenitic single phase structure at room temperature, but if added in a large amount, it hardens, so it was made 0.5% or less.

Si: The amount normally contained as a deoxidizing agent, that is, 1% or less.

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

N: It is necessary to obtain an austenite single-phase structure at room temperature. However, excessive addition causes 0.2% or less of defects during steel making, so it was made 0.2% 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, the present invention will be described specifically with reference to examples.

The 20 types of 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 thermal expansion measurement (1.5t × 5W ×
50L) and a sample for electric resistance measurement (1.5t × 3W × 200L).

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.

As is clear from Table 1, SN with Ni content of 9-14%
The properties of the alloys of the present invention in o.1 to No.9 were equivalent to those of the conventional alloys S.No.10 and No.11 Fe-20Ni-5Cr steel or Fe-22Ni-3Cr steel.

[Effect of the Invention] As described above, the alloy of the present invention has a Ni content of 9 to 14%.
% And Fe-20Ni-5Cr steel or Fe-22Ni-3Cr steel
Since the Ni content is small, an inexpensive high expansion alloy can be provided.

Continuation of the front page (72) Inventor Katsunori Babaen 4976 Tomita, Odai, Shinnanyo-shi, Yamaguchi Prefecture Inside the Steel Research Laboratory, Nissin Steel Co., Ltd. (56) References JP-A-3-31446 (JP, A) JP-A-60- 26642 (JP, A) JP-A-52-3520 (JP, A) JP-B 3-57438 (JP, B2) JP-B 54-3466 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) C22C 38/00 302 C22C 38/58

Claims (1)

(57) [Claims] (1) Ni: 9 to 14% Cr: 6 to 13% C: 0.5% or less Si: 1% or less Mn: 4% or less N: 0.2% or less Co: 2% or less The balance consists of Fe and inevitable impurities. , Having an austenitic single phase structure at room temperature and a thermal expansion coefficient of
0 ^-6 / ° C. or more and less expensive high expansion alloys electrical resistivity is 70μΩ · cm or more at room temperature.