JP2739475B2 - High expansion alloy - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an inexpensive high expansion alloy.

(Conventional technology and problems) The high expansion alloy is composed of a composite member by mechanical joining or welding joining with so-called amber-type low-expansion alloy of Fe-Ni, ordinary steel, stainless steel, etc. It is widely used as a temperature sensor and temperature compensating component in electrical products.

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. Depending on the chemical composition of this Fe-Ni-Cr alloy, martensitic transformation can easily occur and the thermal expansion coefficient can be reduced. Therefore, the composition design is such that the martensitic transformation start point (Ms point) is low. Need to be done.

As a method of controlling the Ms point, for example, Japanese Patent Application Laid-Open No. 58-202985
The following correlation equation between the Ms point and the composition: Ms = 788.4-1358 · (C%)-27.1 · (Si%)-23.8 · (Mn%) -27.9 · (Ni%)-40.3 · ( (Cr%)-1358 · (N%) It is disclosed that there is a relationship given by equation (1).

In order to lower the Ms point, C or Cr having a negative coefficient in equation (1) may be added, but conventionally, the Cr amount was increased. The reason is that if C is added, it has a solid solution strengthening ability as an interstitial element, so that it is considered that the material hardens and adversely affects the manufacturability, and the Ms point can be lowered without having the most adverse effect on the material properties. Cr was used to adjust the Ms point despite the rise in raw material costs because it was thought to be Cr.

(Means for Solving the Problem) However, the present inventors have intensively pursued the relationship between the hardness of the annealed material of the Fe-22Ni-3Cr-based alloy and the C content, and as a result, excessive C
Unless added, the material hardness can be suppressed to a certain level or less, and the effect of lowering the Ms point can be obtained.
By adding C, which is a cheaper raw material, a high expansion alloy having a low raw material cost can be provided.

(Constitution of the Invention) The present invention is based on the following: Ni: 18.0 to 23.0% C: 0.10 to 0.30% Cr: 0.5 to 4.0% Mn: 1.0% or less Si: 1.0% or less The balance consists of Fe and unavoidable impurities. -120 ° C
Provided is a high expansion alloy having a hardness of not more than 250 and a hardness Hv of not more than 250.

 Hereinafter, the reasons for the composition limitation in the present invention will be described.

In the case of Ni: Fe-Ni alloys, the coefficient of thermal expansion becomes the highest around 20%, and the thermal expansion coefficient becomes small if the amount of Ni is too low or too high. An appropriate amount was set to 18.0 to 23.0%.

C: C requires 0.10% or more to lower the Ms point. However, excessive addition causes hardening of the material even if the Ms point is lowered, so the upper limit is about 0.30%.

Since it is not preferable to lower the Cr: Ms point only by adding C from the viewpoint of material hardening, it was determined that Cr should be contained at least 0.5% in order to reinforce the ability of C to lower the Ms point. The addition of a large amount of Cr limits the upper limit by 4.0% to increase the production cost.

Mn, Sn: Since both Mn and Si can be added as deoxidizing agents, the content is usually set to 1.0% or less.

P and S, which are inevitable impurities, adversely affect solidification cracking sensitivity and hot workability. Therefore, it is desirable to reduce P and S as much as possible. P is set to 0.040% or less and S is set to 0.030% or less.

(Specific Disclosure of the Invention) Hereinafter, the present invention will be described based on examples.

FIG. 1 shows the results obtained by arranging the Vickers hardness of the alloys shown in Table 1 and the Ms point calculated from the equation (1) by the C content. As the C content increases, the Ms point decreases monotonously. The hardness decreases with increasing C content up to about 0.1% C, but when it exceeds about 0.1% C, the hardness hardens with increasing C content.

Melt alloys of the components shown in Table 1
Was obtained. Subsequently, the steel ingot is subjected to the steps of hot forging → flaw removal → hot rolling → annealing and polishing → cold rolling → annealing and polishing and the sample for thermal expansion coefficient measurement (1.5 ^t × 5 ^w × 50 ^L ) and hardness A sample for measurement was prepared.

The coefficient of thermal expansion was measured in a temperature range from room temperature to 100 ° C.
Hardness was measured by a Vickers hardness tester under a load of 5 kg.

 Table 1 shows the measurement results of the coefficient of thermal expansion and the hardness.

As shown in Table 1, the alloy of the present invention has an Ms point of -120 ° C.
The thermal expansion coefficient is as low as 19.0 × 10 ⁻⁶ cm / cm / ° C. or more, and the hardness is less than Hv250. On the other hand, in the comparative alloy, when the C value is low, the Ms point is high, and since a part of the structure is martensitic, the coefficient of thermal expansion is 19.0 × 10 ⁻⁶ cm / cm /.
It will be less than ° C. Conversely, when the C value is high, the Ms point is low, and the coefficient of thermal expansion is high, but the material hardness exceeds Hv250, which is not preferable in production.

When the Ni content is out of the range of the present invention, the thermal expansion coefficient decreases.

As described above, the present invention can manufacture and provide an alloy having a high expansion characteristic at a lower cost than before, so that it is possible to further generalize the material for temperature compensating parts and the like, and to carry out the work. Can contribute to development.

[Brief description of the drawings]

FIG. 1 shows the relationship between the C content, hardness, and Ms point of the annealed Fe-22Ni-3Cr alloy.

 ──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Katsuhiko Fukumura 4976 Tomita, Oji, Shinnanyo-shi, Yamaguchi Prefecture Inside Shunan Laboratory, Nissin Steel Co., Ltd. (72) Kazunobu Yamazaki 4976 Tomita, Oaza, Shinnanyo-shi, Yamaguchi Prefecture Shunan Laboratory Co., Ltd. (72) Inventor Osamu Yamamoto 4976 Tomita, Oita, Shinnanyo-shi, Yamaguchi Prefecture Nisshin Steel Corporation Shunan Laboratory Co., Ltd. (56) References JP-A-58-202985 (JP, A) JP-A-59- 215464 (JP, A)

Claims (1)

(57) [Claims] 1. Ni: 18.0 to 23.0% C: 0.10 to 0.30% Cr: 0.5 to 4.0% Mn: 1.0% or less Si: 1.0% or less The balance consists of Fe and unavoidable impurities, and the Ms point is -120 ° C or less. High expansion alloy with a hardness Hv of 250 or less.