JPS58201088A - Bimetal - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a low-temperature bimetal having a high-expansion alloy that prevents a decrease in the coefficient of thermal expansion due to deformation-induced martensitic transformation caused by cold working.

Generally, bimetal/L' has at least two different coefficients of thermal expansion.
By bonding more than one metal or alloy using an appropriate method,
It is a material that is rolled into a plate or strip and has the property of bending due to temperature changes according to the difference in their thermal expansion coefficients, and is widely used as a simple and reliable material that can convert thermal energy into mechanical motion. The high expansion alloy used to form the bimetal is required to have a high coefficient of thermal expansion.

Since bimetals are often used as electrical components, the required volume resistivity of the bimetal is determined by the volume resistivity of the high expansion alloy due to the balance between the low expansion alloy and the intermediate layer metal or alloy inserted in between. It is also adjusted and obtained as a composite. On the other hand, bimetal /I/ can be punched, bent, caulked, etc. into various shapes as a material for mechanical parts, so it requires strength and springiness as well as workability. Corrosion resistance is also required since it is used in such environments.

In bimetals, the required mechanical properties are generally obtained by work hardening during cold rolling, but Fe-Nj-1, which is conventionally used as a high expansion alloy for bimetals,
The 5-80wt%-Crt-15wt% alloy undergoes deformation-induced martensitic transformation during cold working, so the thermal expansion coefficient is higher than that obtained in the annealed state, that is, the thermal expansion coefficient obtained at a cold rolling reduction of θ%. descend. Therefore,
Conventional bimetals using high-expansion alloys have had the drawback of causing a decrease in the amount of displacement with respect to temperature changes, that is, the bending constant, which is the main characteristic of bimetals.

In order to eliminate the drawbacks of the conventional method, the inventors developed Fe-
As a result of various studies on the relationship between the alloy components, the amount of deformation-induced martensite after cold rolling, and the coefficient of thermal expansion for 15-80wt%N:l-1-15wt%Cr alloys, we found that the conventional high-expansion side alloys Fe -15~B□wt%N
i-1-15 wt% Cr alloy can prevent deformation-induced martensitic transformation due to cold rolling when the value of the relational expression between alloy components is below a certain value, resulting in a decrease in the thermal expansion coefficient and curvature constant. We found that this can be prevented.

That is, in the present invention, C0.2wt% or less, Sj-1,
5wt% or less, Mn 2. Owt% or less, Nj-1
5-80wt%.

Contains 5 wt% of crt-i, 06 wt% or less of NO,
Alternatively, in a high-expansion alloy containing 10 wt% or less of MO, and the balance essentially consisting of Fe, C9Si may be
, Mn, Or, Nj-, Nh, or a high-expansion alloy in which the amount of Mo is adjusted and a low-expansion alloy such as an/<, -r alloy containing 85 to 7 wt% Ni are directly joined, or It is a bimetal formed by joining with an intermediate layer alloy interposed between the metal and the metal, and is characterized by preventing deformation-induced martensitic transformation caused by cold rolling, and preventing a decrease in the coefficient of thermal expansion and a decrease in the curvature constant. be.

Q) When Mo is not contained
Sj-%)-(10,9XMn%)-(12,7XNi
%)-(18,4xCr%)-(619,IXN%)・
...(1) (2J When containing Mo
Si%) - (10,9x morbidity) - (12,7XN:1-
%)-(18,4xCr%)-(24,8xMO%)-
(619, IXN%) (2) In the present invention, the low expansion alloy is, for example, the known 35-B
A 7 wt% Nl-Fe based amber alloy may be used, but by lowering the Mn content of the amber alloy and containing T1 at 0.3 wt% or less, it is possible to improve the low expansion side alloy by aging treatment after cold finish rolling of the bimetal. The effect of preventing an increase in the coefficient of thermal expansion is desirable.

Further, when an intermediate layer alloy is used in the present invention, 6 D , CulCu alloy, N1, N1 alloy, etc. are used in order to lower the volume resistivity of the bimetal.

The reason why the components of the high expansion alloy in the present invention are limited will be explained.

Ni15-80wt%, Crl-15wt%U/<Imetal is necessary with a high coefficient of thermal expansion as an alloy on the high expansion side, and is necessary to adjust corrosion resistance and volume resistivity, and outside the above range, a high coefficient of thermal expansion is necessary. It becomes difficult to obtain a suitable volume resistivity. In particular, N1 is 30 wt% and Cr is 11
When it exceeds 5 wt%, the volume resistivity becomes 90 μΩ-1 or more, and the thermal expansion coefficient becomes higher than that of the cold rolled annealed steel.
In the previous state, the value was less than 16.5, and the versatility as a bimetal was lost.

If Cr is less than 1 wt%, corrosion resistance deteriorates, and Ni
, below 15 wt%, corrosion resistance deteriorates and, as mentioned above, it becomes difficult to obtain the combination of high thermal expansion coefficient and required volume resistivity. In addition, the high expansion side alloy in the present invention is Or 1 to 5 wt%, N115 to 30 WtX
K L Te2 X Ni”%+3 X Cr”X≦6
When condition 7 is satisfied, the effect of adjusting the alloy components becomes extremely large.

C is effective in preventing deformation-induced martensitic transformation, but when it exceeds 0.2 wt%, the hardness after cold rolling decreases to HMV.
400 or more, which makes processing into parts difficult, and also forms carbides, which cause corrosion holes to occur and deteriorate corrosion resistance.

Like C, N is also effective in preventing the occurrence of deformation-induced martensitic transformation, but if it is more than 0.06 wt%, the amount of nitrides formed increases, causing corrosion holes to occur, and corrosion resistance worsens.

Sl also becomes difficult to undergo deformation-induced martensitic transformation, but if it exceeds 1.5 WtX, the elongation decreases rapidly, making it difficult to bend into various shapes.

Like C, N, and Si, Mn also undergoes deformation-induced martensi F.
Metamorphosis is less likely to occur, but 2. □ If the amount exceeds WtX, the volume resistivity becomes high and the required volume resistivity cannot be obtained.

Furthermore, when the high expansion alloy of the present invention further contains MO, it has a greater effect of preventing deformation-induced martensitic transformation than MoU Sl-, Mn, Ni, and Or, and is effective in improving corrosion resistance, but at 10 wt% If it exceeds this, the volume resistivity becomes high and the required volume resistivity cannot be obtained.

In addition, the reason why the value of This is caused by a sudden deterioration when exceeding 20%, and a sudden increase in the amount of martensite, resulting in an unstable state.

The present invention will be explained below by way of specific examples.

(Example 1) The alloys shown in Table 1 with alloy numbers 1 to 20 as high-expansion alloys were melted in a high-frequency melting furnace, and the resulting ingots were forged and hot-rolled to a thickness of 7.5 ff. After that, it was cold rolled into a plate with a thickness of 1.6 fl, and this was rolled at 750 ml in a city atmosphere.
A material was sampled from a material that had been annealed at °C x IHr, and cold rolled at 55% to a plate thickness of 0.724.

The plate thickness x width 1.
Two types of square rods of 6m11 x length of 50111 and two types of plates of plate thickness x angle IQn+ were collected, and the square rod samples were heated at 30°C.
The coefficient of thermal expansion was measured in a temperature range of ~300°C, and the amount of martensitic transformation was investigated by performing X-ray diffraction on the plate sample. The results are shown in Table 1.

In Table 1, alloy numbers 1 to 17 are alloys according to the present invention, alloys 18, 19, and 20 are comparative alloys, X represents the X value obtained from equation (1) or (2), and Y represents thermal expansion. .

Figure 1 shows the relationship between X obtained from equation (1) or (2) above and the rate of decrease in thermal expansion coefficient (a) due to cold rolling for the samples of alloy numbers 2 to 20 shown in Table 1. It expresses the relationship.

From FIG. 1, it is clear that the high expansion alloy of the present invention has a small reduction rate (Y) in the coefficient of thermal expansion due to cold rolling, and therefore, when used in bimetals, it is possible to prevent a reduction in the curvature constant. be. Moreover, it was confirmed from the X-ray diffraction results that when the value of the reduction rate (1) exceeds 20%, the amount of martensite increases rapidly, resulting in an unstable state.

(Example 2) In order to manufacture a low-temperature bimetal with a volume resistivity in the vicinity of 78 μΩ-α at room temperature, alloy numbers 7, 15, and 20 in Table 1 of Example 1 were used as high expansion alloys, respectively. Using an amber alloy (36wt%N1-Fe) as a low expansion alloy,
The material of the high-expansion side alloy has a plate thickness of 1 under the same conditions as Example 1.
．． The annealed material of 6fl was used, and the low expansion alloy was also cold-rolled in a cold rolling mill using the same process as in Example 1, using the annealed material with a plate thickness of 1.6 mm, and then subjected to Hj atmosphere. 75 inside
Annealing was performed at 0°C x IHr, and then 25%, 3
5%.

Cold rolling was performed at 45% and 65%, and a 140n sample (plate thickness×plate 1]10+nt×length was taken from each material and the curvature constant was measured. The results are shown in Table 2 and Figure 2.

The method for measuring the tortuosity constant shown in Table 2 and Figure 2 is to fix one end of the sample so that the working length is 1000,
In an oil tank containing low viscosity silicone oil, heat from 15"C to 1C while stirring so that the temperature difference in the oil tank is within 1C.
The temperature was raised to 00'lE over 2 hours, the displacement of the free end (the other end of the bimetal) was measured, and the oil temperature was also measured.The displacement and oil temperature were plotted on graph paper, and the following (3)
) The curvature constant (a) was calculated using the formula.

However, K: Curvature constant Dλ: Displacement at temperature T (, u) on the straight line applied to graph paper by the above method] / amount (pruning D / = graph paper by the above method)゛lot Displacement amount (-) at temperature T/(℃) on the straight line t: Thickness of test piece (T) L: Working length (Dragon) Table 2 Table 3 In addition, in Table 2 and Figure 2, Bimetal of alloy number 7.15)vTf'i Bimetal of the present invention and bimetal of alloy number 20 are bimetals of comparative examples.

(Example 3) In order to obtain a low-temperature bimetal whose volume resistivity at room temperature is around 80 μΩ-α and which is mainly used near room temperature, alloy numbers 2, 18, and 19 in Table 1 of Example 1 were highly expanded. Amber alloy (36 wt.
%N1-Fe), the material of the high expansion side alloy was an annealed material with a plate thickness of 1.6n under the same conditions as in Example 1,
For the low expansion alloy, the plate thickness was reduced to 1 in the same process as in Example 1.
．． Using annealed material of 6=, after cold welding in a cold rolling mill, annealing of 75 (1 In order to obtain test pieces, intermediate rolling, annealing and final cold rolling were performed as shown in Table 3.

As shown in Table 8, a test piece with a thickness of 0.4 fl x a width of 5 fl x a length of 9 Qig was taken, and the curvature constant was measured. Same as 2
(Table 4) 1st One method was used. However, the working length (g) of the test piece was adjusted to 75th edition.

The results of the curve constant are shown in Table 4 and Figure 8.

In Table 4 and FIG. 3, the bimetal with alloy number 2.13 is the bimetal of the present invention, and the bimetal with alloy number 19)v is the bimetal of the comparative example.

As is clear from Example 2.3, by using a high-expansion alloy with specific components, the present invention can prevent a decrease in the coefficient of thermal expansion due to deformation-induced martensitic transformation due to cold working, and has an excellent curvature constant. It can stably provide bimetallic materials, and it has been adjusted to prevent martensitic transformation from occurring, so when used as bimetallic material, it is stable even at low temperatures (-70℃). .

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between the X value of the relational expression of the components of the high-expansion side alloy and the rate of decrease in the coefficient of thermal expansion. Figure 2.3 is a diagram showing the relationship between cold rolling rate and warp constant of bimetal. αQ diagram

Claims (1)

[Claims] (1) CO, 2wt% or less, Si, 1.5wt
% or less, Mn2.0 loading % or less, Ni, 15-30w
t%, Or 1-15 wt%. Contains NO, 06 wt% or less, and X in the following formula is 25
Satisfies the following, X=887.9-(619,IXCX)-(12,3X
Si-%)-(10,9XMn%)-(12,7XNi
%) −(18,4 Bimetal C2) C0.2wt% or less, Si 1.5wt%
Below, Mn 2. OW″llS% or less, Ni-15
−10 wt%, cr ~15 wt%. M○ Contains 10 wt% or less, NO, 06 wt% or less,
And X in the following formula satisfies 25 or less, X==387.9-(619,1X0%)-(12,
'8XSi,%)-(10,9,XMn%)-(12,
7XNi,%) - (18,4XCr%) - (24,8x
Mo%) - (619, IXN%) The balance is substantially composed of Fe, and is characterized by being formed by joining a high expansion side alloy and a low expansion side alloy with or without intervening an intermediate layer metal or alloy. Bimetal