JPH066774B2 - Alloy for strain gauge and method for manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to iron (Fe), chromium (Cr), cobalt (C).
o) and nickel (Ni) as a main component, and tungsten (W), molybdenum (Mo), niobium (Nb), tantalum (Ta) as a first selection component, one or more, and a second One or more selected from copper (Cu), vanadium (V), palladium (Pd), tin (Sn), antimony (Sb), and zirconium (Zr) as a selection component, and manganese (Mn as a third selection component. ),
Aluminum (Al), Silicon (Si), Titanium (T
(i) and germanium (Ge), 1 type or 2 types or more, and 1 to 25% in total of 1 to 25% of elements, and a strain gauge alloy containing a small amount of impurities and a manufacturing method thereof. An object is to provide a strain gauge alloy having a high modulus, a small change in gauge ratio with respect to composition, excellent other properties, and easy to process.

Strain gauges generally use the phenomenon that the electrical resistance of a gauge wire or gauge foil changes due to elastic strain, and conversely measure the amount of strain or stress by measuring the resistance change, and are widely used for strain measurement. Not only is it used in recent years as a mechanical quantity-electric quantity converter element for industrial equipment such as a balanced recorder, a so-called strain sensor.

Strain gauge materials have the following requirements: 1. Large gauge ratio 2. Small thermoelectromotive force against copper 3. Large specific electrical resistance 4. Small temperature coefficient of specific electrical resistance 5. Workability Good and good mechanical properties 6. Inexpensive etc.

By the way, the strain gauge has a structure in which fine metal wires (13 to 25 μm) or foils (3 to 5 μm) are arranged in a lattice or rosette shape, and the method of using the strain gauge is to bond an adhesive to an object to be measured. The strain applied to the object to be measured is indirectly measured from the change in resistance of the gauge.

The sensitivity of the strain gauge is determined by the gauge factor K,
The value of K is generally expressed by the following equation.

Where R is the total resistance of the gauge wire, δ is the Poisson's ratio of the gauge wire, ρ is the specific electrical resistance of the gauge wire, and the total length of the gauge wire. In this formula, δ is approximately 0.3 in metal, so to increase the gauge factor K Must increase Δρ / ρ · (Δ /) ⁻¹ . That is, when tensile deformation is applied, the electronic structure in the length direction of the material changes significantly,
It is necessary to have the property that ρ increases.

In recent years, strain gauges have been widely used in high-sensitivity pressure transducers and load cells, with their application areas expanding more and more with the progress of microcomputers in recent years. Particularly in load cells, in addition to commercial toll scales, it is used for hopper scale and tank scale dynamometers, pressure gauges for rolling and extrusion, industrial feeders such as constant feeders, vehicle weight scales, crane overweight scales, etc. In addition to detecting and instructing the number, weight, pressure, etc. of parts, the factory management by automatic control not only stabilizes the high quality of the products and improves the yield, but also has the purpose of labor saving and energy saving.

However, in automatic control technology, the characteristics of the strain gauge element used in the load cell are an important determinant in order to obtain high precision and high reliability of the measuring device.
Table 1 shows the materials of major strain gauge elements currently known, the gauge factor K, and the copper thermoelectromotive force E.
mf, specific electric resistance ρ, and temperature coefficient Cf of the specific electric resistance ρ are shown.

In Table 1, the Cu-Ni-based alloy is most often used conventionally. This alloy has a characteristic that the temperature coefficient Cf of the specific electric resistance ρ is small, but on the other hand, the value of the gauge factor K and the specific electric resistance ρ are too small, and the thermoelectromotive force Emf with respect to copper is large.
It cannot be said that the properties of strain gauge materials are sufficient. Further, the variation in performance within the same lot or between lots reaches 5 to 10%, which is very unstable. There are merits and demerits in the characteristics of other alloys, and it was difficult to say that the characteristics are sufficient as a substitute for the strain gauge material used conventionally.

The present inventors previously found that Fe-Cr- as a strain gauge material having a large gauge factor K and excellent in various other characteristics.
We have proposed that Co-based alloys are very promising (Japanese Patent Publication No. 45-13229). However, the above-mentioned alloy system has a drawback that the gauge factor K greatly changes with respect to the composition, that is, the variation of the gauge factor with respect to the composition reaches as much as 20%, so that it is very difficult to manufacture a stable product with little variation.

Therefore, the inventors of the present invention have a large gauge factor K in order to obtain a high-performance strain gauge material with little variation.
Continuing research for the purpose of developing an alloy for strain gauges that has little change in gauge ratio with respect to composition, is excellent in other properties, and has good workability such as forging, rolling, and drawing, and a method for producing the same, As a result of trying to improve the Cr-Co alloy, the findings of the present invention have been obtained.

The features of the present invention are as follows.

1st invention By weight ratio, chromium is 5 to 20%, cobalt is 17 to 40%, nickel is 0.01 to 40%, and balance iron is the main component, and tungsten is 7% or less, molybdenum is 10% or less, and niobium is 7% as a first selection component. An alloy for strain gauges, which comprises 1% or less of tantalum 10% or less and a total of 1 to 25%, and has a gauge factor of 2 or more.

Second invention By weight ratio, chromium is 5 to 20%, cobalt is 17 to 40%, nickel is 0.01 to 40%, and balance iron is the main component, and tungsten is 7% or less, molybdenum is 10% or less, and niobium is 7% as a first selection component. Below, 1 or 2 or more tantalum 10% or less, and 10% or less copper, 10% or less vanadium, 20% or less palladium, 5% or less tin, 5% antimony as the second selection component.
An alloy for strain gauges, which comprises 1% to 25% in total of 1% or more of zirconium and 7% or less of zirconium, and has a gage factor of 2 or more.

Third invention By weight ratio, chromium is 5 to 20%, cobalt is 17 to 40%, nickel is 0.01 to 40%, and balance iron is a main component, and tungsten is 7% or less, molybdenum is 10% or less, and niobium is 7% as a first selection component. Hereinafter, one or two or more kinds of tantalum 10% or less and one or two kinds of manganese 10% or less, aluminum 5% or less, silicon 5% or less, titanium 5% or less and germanium 4% or less as a second selection component. An alloy for strain gauges, which comprises 1 to 25% in total of at least one kind and has a gauge ratio of 2 or more.

Fourth invention By weight ratio, chromium is 5 to 20%, cobalt is 17 to 40%, nickel is 0.01 to 40%, and balance iron is the main component, and tungsten is 7% or less, molybdenum is 10% or less, and niobium is 7% as a first selection component. Below, 1 or 2 or more kinds of tantalum 10% or less, and 10% or less copper and 10% vanadium as the second selection component.
Below, palladium 20% or less, tin 5% or less, antimony 5
% Or less and zirconium 7% or less, or one or two or more, and as a third selection component, manganese 10% or less, aluminum 5% or less, silicon 5% or less, titanium 5% or less, and germanium 4% or less, or Total 1 with 2 or more
An alloy for strain gauges, which has a gauge ratio of 2 to 25%.

Fifth Invention By weight ratio, chromium is 5 to 20%, cobalt is 17 to 40%, nickel is 0.01 to 40%, and balance iron is a main component, and copper is 10% or less, vanadium is 10% or less, and palladium is 20 as a first selection component.
%, Tin 5% or less, antimony 5% or less, zirconium 7% or less, and a total of 1 to 25% of 1 type or 2 types or more and a gauge ratio of 2 or more. .

Sixth invention By weight ratio, chromium is 5 to 20%, cobalt is 17 to 40%, nickel is 0.01 to 40%, and balance iron is the main component, and manganese is 10% or less, aluminum is 5% or less, and silicon is 5% as the first selection component. An alloy for strain gauges, which comprises one or more of titanium% or less and germanium of 4% or less and a total of 1 to 25%, and has a gauge ratio of 2 or more.

Seventh invention By weight ratio, chromium is 5 to 20%, cobalt is 17 to 40%, nickel is 0.01 to 40%, and balance iron is the main component, and copper is 10% or less, vanadium is 10% or less, and palladium is 20 as a first selection component.
% Or less, tin 5% or less, antimony 5% or less and zirconium 7% or less 1 type or 2 or more types, and manganese 10% or less, aluminum 5% or less, silicon 5% or less, titanium 5% or less as the second selection component. And an alloy for strain gauges, which has a gauge ratio of 2 or more, with a total of 1 to 25% of germanium 4% or less.

Eighth invention By weight ratio, chromium is 5 to 20%, cobalt is 17 to 40%, nickel is 0.01 to 40%, and balance iron is the main component, and tungsten is 7% or less, molybdenum is 10% or less, and niobium is 7% as the first selection component. Below, 1 or 2 or more tantalum 10% or less, and 10% or less copper, 10% or less vanadium, 20% or less palladium, 5% or less tin, 5% antimony as the second selection component.
1 or 2 or more and less than or equal to 7% zirconium, and 1 or 2 or less than 10% of manganese, 5% or less of aluminum, 5% or less of silicon, 5% or less of titanium and 4% or less of germanium as a third selective component. Total 1 above
Alloys consisting of ~ 25% are subjected to cold working at a working rate of 1 to 98%, and by heating this at a temperature of 400 ° C or less for 1 minute or more and 100 hours or less, the gauge characteristics are stable and the gauge rate is A method for producing an alloy for strain gauges, which comprises obtaining an alloy having two or more.

Hereinafter, the present invention will be described in detail with reference to the drawings.

In order to produce the alloy of the present invention, firstly Cr 5 to 20%, Co 17 to 40%, Ni 0.01 to
40%, balance Fe and W7% or less of the first selected component, Mo10%
Hereinafter, one or more of Nb 7% or less and Ta 10% or less, and Cu 10% or less, V 10% or less, P as the second selection component
d20% or less, Sn5% or less, Sb5% or less, Zr7% or less, one or more kinds, and Mn10% as a third selection component
Hereinafter, an alloy containing an appropriate amount of one or more of Al 5% or less, Si 5% or less, Ti 5% or less, and Ge 4% or less and a total of 1 to 25% in air, preferably in a non-oxidizing atmosphere or in vacuum. After melting in an appropriate melting furnace, add a small amount (1% or less) of calcium alloy, magnesium alloy or other deoxidizing agent and desulfurizing agent to remove impurities as much as possible, stir well, and compositionally A homogeneous molten alloy is obtained.

Next, this is poured into a mold of an appropriate shape and size to obtain a healthy casting soul, and this casting soul is subjected to a method such as forging, rolling or drawing at a high temperature or a normal temperature, and a working rate of 1% to 98%. Perform the following cold working to make a wire with the desired shape, for example, a wire with a diameter of 0.06 mm or a foil with a thickness of 0.02 mm, leave this wire or foil as it is after the above processing, or in hydrogen or another suitable material. A target sample is obtained by applying a heat treatment of heating at a temperature of 400 ° C. or less for 1 minute or more and 100 hours or less in a non-oxidizing gas or in a vacuum. With respect to the alloy sample obtained by the above method, the gauge factor K, the thermoelectromotive force Emf with copper, the non-electrical resistance ρ, and the temperature coefficient Cf of the non-electrical resistance ρ were measured. Electromotive force Emf: ± 3 μV / ° C or less, value of specific electric resistance ρ:
68 to 90 μΩ-cm and temperature coefficient of specific electrical resistance ρ Cf: ± 10
An alloy for a strain gauge having a characteristic of not more than × 10 ⁻⁴ / ° C. and having a characteristic that the composition factor of the gauge factor K is extremely small can be obtained.

FIG. 1 shows the effect of the cold working rate on the gauge factor K. As can be seen from the figure, the gage factor K before processing is 2 or less in any alloy sample, but the gage factor sharply increases to a substantially constant value by the processing. . The working rate at which the gauge factor K is 2 or more is 1% in any alloy sample.
It is clear that this is the end. Therefore, the cold working has an effect of obtaining a high gauge ratio by forming a dense worked structure, but is particularly remarkable when the working ratio is 20% or more. Also, the heat treatment (heat treatment at a temperature of 200 ° C to 400 ° C below the recrystallization temperature) performed after the above cold working removes a part of internal strain due to working,
It has the effect of stabilizing the gauge factor and other characteristics. In that case, the higher the heating temperature or the longer the heating time, the more remarkable the effect. Of course, if the heating temperature is high, the heating time may be shorter, and conversely, if the heating temperature is lower, the heating time should be longer.

Next, the reasons for limiting the components of the alloy of the present invention will be described.

The main components of the composition of the alloy of the present invention are Cr = 5 to 20%, Co = 17
.About.40%, Ni = 0.01 to 40%, and the balance Fe, as shown in FIGS. 2 to 4, Examples, Tables 4 and 5, the gauge of the composition range. Rate K is 2
Although the above shows excellent gauge characteristics and good workability, if the composition deviates from this range, the gauge characteristics will deteriorate and the desired characteristics will not be obtained. This is because it is unsuitable as a gauge alloy.

In the present invention, tungsten 7 is used as the first selection component.
% Or less, molybdenum 10% or less, niobium 7% or less, tantalum 10% or less, total of 1 to 25% of 1 type or 2 types or more is the reason that there is an equal effect of increasing the gauge ratio below the upper limit of each component. However, if the upper limit is exceeded, the desired effect cannot be achieved. The total amount of the first selected component is 1 to 25%, and if the upper limit is exceeded, the effect of increasing the gauge factor cannot be expected. Further, even if the first selection component is 1% or less, the effect of increasing the gauge factor cannot be achieved.

Next, in the present invention, as the second selection component, copper 10% or less, vanadium 10% or less, palladium 20% or less, tin 5%
Hereinafter, the reason for adding one or more of antimony 5% or less and zirconium 7% or less is that the gauge ratio of the alloy of the present invention is slightly lowered, but the electrical characteristics (copper thermoelectromotive force, specific electrical resistance, specific electrical resistance This is because it is effective in improving the temperature coefficient).

Further, in the alloy of the present invention, the reason for adding one or more kinds of manganese 10% or less, aluminum 5% or less, silicon 5% or less, titanium 5% or less and germanium 4% or less as the third selective component is This is because if the component (1) is added below its upper limit, the gauge ratio will be slightly lowered, but the workability will be improved.

Next, examples of the present invention will be described.

Example 1 Alloy No. 117 (composition Fe = 32.8%, Cr = 14.0%, Co
= 28.0%, Ni = 18.7%, W = 6.5% alloy production) As raw materials, 99.97% pure electrolytic iron, 99.44% pure metallic chromium, 99.59% pure electrolytic cobalt, 99.8% pure electrolytic nickel and 99.8% % Pure electrolytic tungsten was used. To make a sample, the raw material was put into an alumina crucible with a total weight of 100 g and melted in a high frequency induction electric furnace in air while blowing argon gas on the surface to prevent oxidation. Then, the mixture was well stirred to form a homogeneous molten alloy. Next, the molten alloy was cast into an iron mold having an inner diameter of 10 mm and a height of 120 mm, and the obtained soul was cast at 1000 ° C. to form a round bar having an outer diameter of 5 mm. After further intermediate annealing at 1000 ° C, swage and cold drawing to make the diameter 0.5 mm, then again perform intermediate annealing at 1000 ° C to make cold drawing thin wire with diameter 0.06 mm and length 70 cm. A sample was cut into 70 cm. The final processing rate (area reduction rate) in this case is 98%. These various processes could be easily performed at high temperature and room temperature. The properties of this sample corresponding to the processing and heat treatment conditions are shown in Table 2.

Example 2 Alloy No. 205 (composition Fe = 30.4%, Cr = 8.7%, Co =
21.7%, Ni = 26.1%, Cu = 8.7%, W = 4.4%) Manufacture of alloy The raw materials used were iron, chromium, cobalt, nickel and tungsten of the same purity as in Example 1 and copper of 99.97% purity. The method for manufacturing the sample is the same as that in the first embodiment. The samples were subjected to various processing and heat treatments to obtain the characteristics shown in Table 3.

Typical alloys belonging to the alloy region of the present invention have characteristic values,
Table 4 shows the comparison with the Fe-Cr-Co ternary alloy.

Figure 2 shows Fe-15% C obtained by cold drawing with a working rate of 98%.
r-0 to 50% Co comparative alloy (Ni = 0%) and different amounts of Ni were added to this alloy (Fe-15% Cr-0-
50% Co) + Ni-based alloy Ni +20 to +60 in the outer frame
FIG. 6 is a curve diagram showing the relationship between the gauge factor K and the amount of Co when% is the composition parameter.

The composition of each of Fe, Cr, Co and Ni shown in the figure differs depending on the amount of Ni added. Therefore, the method for obtaining them will be described below.

The alloy composition is 10% of Fe-15% Cr-0 to 50% Co alloy.
The total amount of Ni added to this is 20%, 30%, 40%, 50% or 60% as 120%, 130%, 140%, respectively.
%, 150% or 160%. That is, the composition formula of each curve in FIG. 2 can be written as follows.

In case of curve of Ni = + 20 (Fe-15% Cr-0-50% Co) + 20% Ni → total composition 120% In case of curve of Ni = + 30% (Fe-15% Cr-0-50%) Co) + 30% Ni → total composition of 130% Ni = + 40% curve (Fe-15% Cr-0 to 50% Co) + 40% Ni → total composition of 140% Ni = + 50% curve (Fe-15% Cr-0 to 50% Co) + 50% Ni → total of composition 150% Ni = +60 In case of curve, (Fe-15% Cr-0 to 50% Co) + 60% Ni → composition Total 160% As described above, it can be seen that the total amount of alloy varies depending on the amount of Ni added. The notation method for converting the total amount of the entire alloy into 100% can be obtained by dividing the composition amount of each component in the above composition formula by the total amount of the composition to which Ni is added and further multiplying by 100.

That is, the conversion formula is V = (Vo / VT) × 100% (1) where V is the composition amount of each element in the 100% notation method, Vo
And VT are the compositional amount of each element and the total compositional amount in the composition formula of Ni addition.

For example, in the case of a Ni = + 20% curve in the outer frame, the conversion formula
Using (1), it is expressed as (composition amount / 120) × 100 from Fe-12.5% Cr-0 to 41.7% Co-16.7% Ni, and the total amount of the composition of this alloy is 100%.

That is, in FIGS. 2 to 4, Ni = + 30% is Ni = 23.1%, Ni = + 40% is Ni = 28.6%, and Ni = +.
50% can be converted into Ni = 33.3%, and Ni = + 60 can be converted into Ni = 37.5%.

As shown in FIG. 2, the gauge factor K of the Fe-15% Cr-Co ternary alloy decreases with an increase in the amount of Co, but it is the basic alloy of the present invention (Fe-15% Cr-0-40% Co). )
In the case of + Ni-based alloy, the addition of Ni reduces the C content.
The gauge factor K on the o side sharply decreases. Therefore C
A region where the gauge factor K is maximum with respect to the o-axis appears.
That is, in the portion where the gauge factor K shows the maximum, the amount of Co
It shows that it has an invariable gauge factor for 40% or less. This maximum gradually increases C as the amount of Ni added increases.
It moves to the side where the amount of o is small, and the maximum value becomes smaller accordingly, and the gauge factor becomes 3 or less in the curve of Ni = + 60% regardless of the amount of Co. For example, Ni = + 20% (N
(i = 16.7%), the gauge factor K in the range of Co27 to 30% is 3.90 to 3.91, which can be regarded as an almost constant value. Fe-15% Cr-Co ternary comparison alloy This is a major feature not seen in the curve of (Ni = 0%).

FIG. 3 shows samples of the basic alloy Fe—Cr—Co—Ni alloy of the present invention obtained by cold drawing at a working rate of 98%.
FIG. 6 is a curve diagram showing the relationship between the gauge ratio K and the amount of Ni when the composition parameter is Co of 25 to 40% with a constant amount of Cr of 15%.

The change of the gauge factor with respect to the Ni amount is generally Ni +10 to +15
%, And a maximum at Ni + 20 to + 25%, and then gradually decreases as the Ni content increases. And, it is clear that the state of the change has little relation to the Co amount except for the case of Co 0%. In FIG. 3 as well, it can be seen that K shows invariance in the composition region having the minimum and maximum as in FIG. As is clear from FIG. 3, by adding Ni to the Fe—Cr—Co based alloy, the composition dependence of the gauge factor K is reduced and it becomes stable between K = 3 and 4.

FIG. 4 shows the thermoelectric power Emf to copper, the specific electrical resistance ρ, and the temperature coefficient Cf of the specific electrical resistance ρ for the same sample as in FIG.
The characteristics of are shown. As shown in the figure, the thermoelectromotive force against copper Emf
Changes intricately with composition, and is +3 to -4 μV / ° C,
It can be seen that it is much smaller than the value of the conventional Cu-Ni alloy (see Table 1). Especially in the composition of Ni35% which shows the maximum of the electromotive force Emf with respect to copper, at about 1 μV / ° C. or less,
Since an extremely small value is exhibited by arbitrarily selecting the alloy composition, stable performance can be exhibited in a device using a DC power supply for application. Specific electrical resistance ρ is Fe that does not include Co
In the alloys of the present invention except for the -15% Cr-Ni comparative alloy, Co
It shows a minimum at about 15% Ni regardless of the amount. And the value is as large as 68 to 90 μΩcm. The temperature coefficient Cf of the specific electric resistance ρ almost corresponds to the change of ρ, and shows the maximum at Ni15%. The maximum Cf value is + 10 × 10 ^-4 / ℃ and Cu-N
It is much larger than the + 20 × 10 ^-6 / ° C of i-based alloys, but can be offset by using a compensation circuit in the case of ± 10 × 10 ^-4 / ° C or less.

Fig. 5 shows the heating temperature (strain relief heat treatment temperature) dependence of the gauge factor K after cold working with a working rate of 90%. It is extremely effective in keeping K at 2 to 4, but it shows that the gauge strain K decreases when the heating temperature is set to 400 ° C. or higher and the heating time is lengthened.

FIG. 6 shows the dependence of the gauge ratio K of the alloys of the present invention (alloy numbers 117, 205 and 224) and the comparative alloy No. 7 (Fe-15% Cr-35% Co) on the machining rate. It shows that the gauge factor K is 2 to 4.2 in the region of 1 to 95%. A major feature of the alloy of the present invention is that the gauge ratio does not change in a region where the working ratio is wider than that of the comparative alloy.

For the above reasons, the cold working rate is limited to 1 to 98%.

FIG. 7, FIG. 8 and FIG. 9 show the heating time dependency of the gauge factor K after cold working (working rate 90%) of the alloy of the present invention, which is from 1 minute to 100 hours at 200 to 500 ° C. The result of performing heat treatment at is that the higher the heating temperature for 100 hours or more,
The gauge factor K tends to decrease, which indicates that the limit temperature and time are such that the gauge factor K holds a value of 2 or more at 400 ° C. for 100 hours or less.

Figures 10 (A) and (B) show Ni = 16.7% in Figure 2.
Additive elements Cu, W, Mo, Nb, T affecting the gauge factor K of the basic alloy of the present invention (Fe-15% Cr-30% Co-16.7% Ni) showing a maximum in the curve of (Ni = + 20%)
a, V, Pd, Sn, Sb, Mn, Al, Si, Ti,
The effect of Ge or Zr is shown. In FIG. 10 (A), M
For curves o and Ta, Mo = 0 to 10 and Ta =
In each composition region of 0 to 7%, the gauge ratio shows a value larger than that of the basic alloy of the present invention. Similarly, also in FIG. 10 (B), in the case of the curve of W, W = 0 to 0
In the composition region of 9%, the gauge factor shows a value larger than that of the symmetrical base alloy. In the case of the Nb curve, the gauge factor hardly changes with the Nb amount. That is, the gauge ratio is increased by adding Mo, Ta, W and Nb, or does not have a great influence, but other than these, Cu, V, Pd, Sn, Sb, Mn, Al, Si,
It was revealed that Ti, Ge, Zr and the like slightly reduce the gauge factor.

FIG. 11 shows the electric characteristics (B) other than the gauge factor, that is, regarding the thermoelectromotive force Emf to copper, the specific electric resistance ρ, and the temperature coefficient Cf of the specific electric resistance ρ, the basic alloy of the present invention (Fe-15%
The effect of the additive element on Cr-30% Co + 20% Ni) is shown.

Thermoelectromotive force Emf for copper and specific electrical resistance ρ are appropriate for Cu, P
The performance is improved by adding d, V, Sn, and Sb, and the temperature coefficient Cf of the specific electric resistance ρ is all decreased.

As described above, the gauge characteristics of the alloy of the present invention are excellent over a wide range of compositions. That is, as can be seen from Examples 1 to 2 and Table 4 and FIGS. 2 to 4, Fe composed of Cr 5 to 20%, Co 17 to 40%, Ni 0.01 to 40%, and the balance Fe. -Cr-Co-Ni-based quaternary alloy with one or two or more of the first selection component W, Mo, Nb, Ta, and Cu, V, Pd, S as the second selection component
Also in the case of an alloy containing one or two or more of n, Sb and Zr and one or two or more of Mn, Al, Si, Ti and Ge as a third selection component, a total of 1 to 25%, The gauge characteristics are the values shown above for the characteristics of the conventional Cu-Ni alloy, that is, K = 2.04 to 2.12 and Emf =-.
43 μV / ° C., ρ = 45 to 49 μΩ-cm and Cf = ± 0.2 × 10
Comprehensive evaluation in comparison with ^-4 / ° C is quite comparable and extremely excellent.

Since the alloy of the present invention has an unprecedented advantage in that the gauge factor K is large and the composition dependency of K is almost nonexistent, it is extremely useful as a strain gauge for a load cell that requires high sensitivity and high stability. Suitable for The alloy of the present invention is used in a worked state or after being subjected to a heat treatment at a low temperature of about 400 ° C. or less, and it is used at 300 ° C. as seen in Examples.
Below, the characteristics show only slight changes. But 400
The characteristics change rapidly above ℃. Further, the alloy of the present invention is forged, rolled, drawn, at room temperature and at high temperature.
Processing such as swaging is easy and has great industrial benefits.

Next, in the alloy of the present invention, the composition of the alloy should be Cr5 to 20.
%, Co17 to 40%, Ni0.01 to 40% and the balance Fe as main components, and an element added as a first selection component is W7% or less, Mo10% or less, Nb7% or less, Ta10% or less, or 2 or more. Species or more, Cu 10% or less as the second selection component, V10
% Or less, Pd 20% or less, Sn 5% or less, Sb 5% or less,
1 or 2 or more Zr 7% or less, Mn 10% or less, Al 5% or less, Si 5% or less, Ti 5% as a third selection component
The reason for limiting below and Ge 4% or less is that, as is clear from FIGS. 2 to 4, each example and Table 4, the gauge ratio K of the composition range is 2 or more, and excellent gauge characteristics are exhibited. Although the workability is also good, if the composition deviates from this range, not only the gauge characteristics will deteriorate and the desired characteristics will not be obtained, but also the processing will become difficult and it will be unsuitable as a strain gauge alloy. is there. Table 5 shows the relationship between the composition of the main component and various conditions.

Further, Table 6 shows electrical characteristics (B) and machinability (C) which are summarized as a gauge factor (A) at a working rate of 1% or more, a specific electric resistance, a temperature coefficient of electric resistance, and a thermoelectromotive force with respect to copper. The relationship with the additive element or composition is shown. In the table, those that are particularly improved are indicated by ⊚, those that are improved are indicated by ◯, those that do not change are indicated by −, those that deteriorated are indicated by Δ, and those that deteriorated are indicated by ×.

Furthermore, the basic alloys are Cr 5-20%, Co 17-40%, N
An alloy having a composition range of 0.01 to 40% i and the balance Fe has a gauge factor K of 2 or more, and has a feature that the composition dependency of the gauge factor is extremely small, and further has good workability. Furthermore, when various elements are added, various characteristics are exhibited. That is, from Table 6, if only the particularly improved evaluation (⊚) is selected, in item A (gauge ratio), W, Mo, Nb,
The effect of improving the gauge factor K is particularly remarkable by the addition of Ta and Ta. In item B (electrical characteristics), Cu,
The addition of V, Pd, Sn, Sb, and Zr has a gauge factor K
Other than the above, it has an effect of particularly improving the gage characteristics, and in item C (workability), the addition of Mn, Al, Si, Ti and Ge has a particularly remarkable effect of improving the forging process and the cold drawing process. Table 7 summarizes the above results. That is, Table 7 shows the relationship between the combination of the items (A gauge ratio), (B electrical characteristics) and (C workability) in Table 6 and the additive element in which the improvement effect is particularly remarkable in each item. It is a thing.

Further, in the alloy of the present invention, the cold working rate (area reduction rate) is 1
As is apparent from FIGS. 1 and 6, the reason why the percentage is limited to at least 1% is that the gage factor K with a working rate of 1% or more shows a high value of 2 or more, but the gage factor K is small with a working rate of less than this. Not only that, it becomes difficult to control the processing rate in manufacturing,
This is because it is unsuitable as a method for producing a strain gauge alloy.

In the alloy of the present invention, the heating temperature after cold working is 400 ° C.
As is clear from Tables 2 to 4 and FIG. 5, the reason for limiting to the following is that the gauge factor changes only slightly at 400 ° C or lower, but when heating at a temperature of 400 ° C or higher, the specific electric This is because the temperature coefficient Cf of the resistance exceeds the value of 10 × 10 ⁻⁴ / ° C. and deviates from the required characteristics of the strain gauge, which makes it unsuitable as a method for producing a strain gauge alloy.

Finally, in the alloy of the present invention, after cold working, further 400 ° C
When heating at the following temperature, heating time is 1 minute or more 100
The reason for limiting to less than or equal to the time is as follows.
As is clear from Fig. 9, when the heat treatment is performed within the above time range, not only does the gauge ratio not change so much, but the processing strain is partly removed so that the gauge ratio is stable, so that the strain does not change over time. It is possible to provide a gauge alloy. However, if the heating time is less than 1 minute, the stability of the gauge ratio is poor, and if it exceeds 100 hours, the gauge ratio deteriorates rapidly, which makes it unsuitable as a method for producing strain gauge alloys. Because it will be.

As described above, according to the present invention, not only is it possible to obtain a material having no variation in the composition of the gauge factor as compared with a conventionally used Ni-Cu alloy or a known Fe-Cr-Co alloy, but also Moreover, there is a great industrial advantage to provide an alloy having excellent gauge characteristics and good workability and a method for producing the alloy.

[Brief description of drawings]

FIG. 1 is a curve diagram showing the relationship between the gauge factor K and the cold working rate of a typical alloy of the present invention, and FIG. 2 is different from the Fe-15% Cr-Co alloy subjected to 98% cold working. Of Ni (20, 30, 40, 50 or 60
%) Is a curve diagram showing the relationship between the gauge ratio K and the amount of Co of the basic alloy of the present invention including FIG. 3, FIG. 3 is a Fe-15% Cr-Ni alloy which has been 98% cold worked, and different amounts of Co. FIG. 4 is a curve diagram showing the relationship between the gauge ratio K and the amount of Ni of the basic alloy of the present invention containing Co (25, 30, 35 or 40%), and FIG. 4 is the same alloy as that used in FIG. FIG. 5 is a characteristic diagram showing the relationship between the thermoelectromotive force Emf, the specific electric resistance ρ, the temperature coefficient Cf of the specific electric resistance, and the amount of Ni. FIG. FIG. 6 is a characteristic diagram showing the processing temperature dependency, FIG. 6 is a characteristic diagram showing the processing rate dependency of the gauge ratio of the present invention alloy, and FIG. 7 is a gauge ratio of the present invention alloy after cold working (working rate 90%). Fig. 8 is a characteristic diagram showing the processing time dependence of Fig. 8 shows the gauge ratio of the alloy of the present invention (alloy No. 205) after cold working (working rate 98%). Fig. 9 is a characteristic diagram showing the heating time dependence of Fig. 9, Fig. 9 is a characteristic diagram showing the heating time dependence of the gauge factor of the alloy of the present invention (alloy No. 117) after cold working (working rate 98%), Fig. 10 ( A) and (B) are the basic alloys (Fe-
Fig. 11 is a characteristic diagram showing the effect of additional elements on the gauge factor of 15% Cr-30% Co-16.7% Ni, Fig. 11 is the basic alloy of the present invention (Fe-15% Cr-30% Co).
It is a characteristic view showing the effect of the additional element on the electrical characteristics of -16.7% Ni).

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location G01B 7/18 J 9106-2F G01N 27/20 Z 7414-2J

Claims (8)

[Claims] 1. A weight ratio of chromium 5 to 20% and cobalt 17 to
40%, nickel 0.01-40% and balance iron as main components,
Tungsten 7% or less, molybdenum as the first selection component
10% or less, niobium 7% or less, tantalum 10% or less 1 type or 2 or more types in total, and 1 to 25%, with a gage factor of 2
An alloy for strain gauges having the above. 2. A weight ratio of chromium is 5 to 20%, and cobalt is 17 to
40%, nickel 0.01-40% and balance iron as main components,
Tungsten 7% or less, molybdenum as the first selection component
1% or more of 10% or less, niobium 7% or less, tantalum 10% or less, and copper 10% or less, vanadium 10% or less, palladium 20% or less, tin 5% or less, antimony 5% as a second selection component. 1% to 25% in total and 1% to 2% or more of zirconium 7% or less, and the gage factor is 2
An alloy for strain gauges having the above. 3. By weight ratio, chromium 5-20%, cobalt 17-
40%, nickel 0.01-40% and balance iron as main components,
Tungsten 7% or less, molybdenum as the first selection component
1% or more of 10% or less, niobium 7% or less, tantalum 10% or less, and as the second selection component, manganese 10% or less, aluminum 5% or less, silicon 5% or less, titanium 5% or less, and germanium 4 % Or less, and a total of 1 to 25%, and a gauge ratio of 2 or more. 4. Chromium 5 to 20% and cobalt 17 to 17 by weight.
40%, nickel 0.01-40% and balance iron as main components,
Tungsten 7% or less, molybdenum as the first selection component
1% or more of 10% or less, niobium 7% or less, tantalum 10% or less, and as the second selection component, copper 10% or less, vanadium 10% or less, palladium 20% or less, tin 5% or less,
1 or 2 or more of antimony 5% or less and zirconium 7% or less, and as a third selective component, manganese 10% or less, aluminum 5% or less, silicon 5% or less, titanium 5% or less and germanium 4% or less 1 An alloy for strain gauges having a total of 1 to 25% of one kind or two or more kinds and a gauge ratio of 2 or more. 5. Chromium 5 to 20% and cobalt 17 to 17 by weight.
40%, nickel 0.01-40% and balance iron as main components,
As the first selection component, copper 10% or less, vanadium 10% or less,
Palladium 20% or less, tin 5% or less, antimony 5% or less, zirconium 7% or less 1 type or 2 types or more in total 1
An alloy for strain gauges, characterized in that the strain gauge has a gauge ratio of 2 or more. 6. A weight ratio of chromium is 5 to 20% and cobalt is 17 to
40%, nickel 0.01-40% and balance iron as main components,
Manganese 10% or less, aluminum 5 as the first selection component
%, Silicon 5% or less, titanium 5% or less, and germanium 4% or less, and a total of 1 to 25%, and a strain gauge alloy having a gauge factor of 2 or more. . 7. A weight ratio of chromium is 5 to 20% and cobalt is 17 to
40%, nickel 0.01-40% and balance iron as main components,
As the first selection component, copper 10% or less, vanadium 10% or less,
One or more of 20% or less of palladium, 5% or less of tin, 5% or less of antimony and 7% or less of zirconium, and 10% or less of manganese as a second selection component, 5% of aluminum.
An alloy for strain gauges, which comprises 1% to 25% in total of 5% or less of silicon, 5% or less of titanium and 4% or less of germanium in total, and has a gauge factor of 2 or more. 8. Chromium 5 to 20% and cobalt 17 to 17 by weight.
40%, nickel 0.01-40% and balance iron as main components,
Tungsten 7% or less, molybdenum as the first selection component
1% or more of 10% or less, niobium 7% or less, tantalum 10% or less, and copper 10% or less, vanadium 10% or less, palladium 20% or less, tin 5% or less, antimony 5% as a second selection component. 1 or 2 or more and less than or equal to 7% zirconium, and 1 or 2 or less than 10% of manganese, 5% or less of aluminum, 5% or less of silicon, 5% or less of titanium and 4% or less of germanium as a third selective component. The alloy consisting of 1 to 25% in total is subjected to cold working with a working rate of 1 to 98%, and the gauge characteristics are stabilized by heating this at a temperature of 400 ° C or less for 1 minute or more and 100 hours or less. And a method for producing an alloy for strain gauges, characterized in that an alloy having a gauge factor of 2 or more is obtained.