EP2129808A2 - Austenitic iron-nickel-chromium-copper alloy - Google Patents

Abstract

The invention relates to an austenitic iron/nickel/chromium/copper alloy, the composition of which comprises in % by weight: 24% ≤ Ni ≤ 36%; Cr ≥ 0.02%; Cu ≥ 0.1%; Cu + Co ≤ 15%; 0.01 ≤ Mn ≤ 6%; 0.02 ≤ Si ≤ 2%; 0 ≤ Al + Ti ≤ 3%; 0 ≤ C ≤ 2%; 0 ≤ V + W ≤ 6%; 0 ≤ Nb + Zr ≤ 0.5%; 0 ≤ Mo ≤ 8; Sn ≤ 1; 0 ≤ B ≤ 0.006%; 0 ≤ S + Se + Sb ≤ 0.008%; 0 ≤ Ca + Mg ≤ 0.020%; the reminder being iron and impurities resulting from the smelting, the percentages of nickel, chromium, copper and cobalt being such that the alloy also meets the following conditions: Co < Cu; Co < 4% if Cr > 7.5%; Eq1 > 28% where Eq1 = Ni + 1.2 Cr + (Cu/5); Cr < 7.5% if Ni > 32.5%, and the manganese content also meeting the following conditions : if Eq3 ≥ 205, Mn ≤ Ni - 27.5 + Cu - Cr; if 180.5 ≤ Eq3 ≤ 205, Mn ≤ 4%; if Eq3 ≤ 180.5, Mn < 2% where Eq3 = 6Ni - 2.5X + 4(Cu+Co) and X = Cr+Mo+V+W+Si+Al.

Description

 Austenitic iron-nickel-chrome-copper alloy

The present invention relates to an austenitic iron-nickel chromium-copper alloy, more particularly intended for the manufacture of electromagnetic devices.

Nickel-rich iron-nickel and iron-nickel-chromium alloys have been known for a long time and are used in many applications in electrical engineering (electronics, electrical engineering), visualization, energy transport, thermal regulation or electrical engineering. electrical safety, thanks to their original and varied physical properties.

Thus, they have thermal dilatabilities between 20 and 100 ⁰ C between 2 and 13.10 ^"6 Z ⁰ C according to their composition, which is an exceptional feature for a ductile material, specific to a few materials.

They also have good to very good resistance to aqueous corrosion, especially as the percentage of nickel or chromium increases.

There is also a great aptitude for shaping, linked to the single-phase austenitic structure, allowing easy rolling at very low thicknesses, cutting, punching, stamping, high-speed stamping.

Their ferromagnetic behavior, characterized by the existence of a Curie point T _c (disappearance temperature of ferromagnetism) is also remarkable as well as their magnetic properties (relative permeability μ _r , coercive field H _c , magnetic losses P).

These are very good, going in the direction of low energy consumption to magnetize these alloys _. Thus, these iron-nickel and iron-nickel-chromium alloys have long been used in electromagnetic applications where it is imperative either to save energy (watchmaking electric motors, high-sensitivity differential circuit breaker relays, high-speed motors and low temperature, etc.), have a very small hysteresis to significantly limit the measurement dispersion of the magnetic sensors (current transformer, DC sensor, resolvers and synchro-resolvers) or hysteretic losses (measurement transformer, modem ...), or still to offer a very privileged channel of the magnetic fluxes as in some magnetic cylinder of high dynamics actuator (electromagnetic injector of gasoline for example), in the motor-wheel, in the passive magnetic shieldings with strong attenuation.

Iron-nickel alloys, whose coercive field is generally less than 125 mOe, thus allow a real jump in the energy consumption of electrical systems, compared with traditional silicon-type materials, since they reach coercive fields. of the order of 190 mOe in a single direction which is of little interest, or more generally are 500 to 1250 mOe when the application needs to convey the magnetic flux in different directions of the material (motors, generators, etc.).

However, there is a need for the improvement of certain properties of these iron-nickel alloys, such as those relating to corrosion resistance in acidic aqueous media and to salt spray corrosion, which are not always sufficient in certain aggressive environments.

In addition, the production of sheets of these alloys comprises industrial heat treatments in atmospheres often low purity, resulting in the formation of an oxidized layer on the surface which protects the base metal against greater oxidation. But, this surface layer is very little adherent and very mechanically weak, which makes its protective action ineffective.

The object of the present invention is to remedy these drawbacks by proposing an alloy composition having an acidic aqueous corrosion resistance and improved salt spray corrosion, capable of forming a solid surface oxidation layer. and adherent, which can be used for many applications and has a reduced cost. For this purpose, the invention firstly relates to an austenitic iron-nickel-chromium-copper alloy whose composition comprises in% by weight:

24% <Ni <36%

Cr> 0.02% Cu> 0.1%

Cu + Co ≤ 15% 0.01 <Mn ≤ 6% 0.02 ≤ Si <2% 0 <Al + Ti <3% 0 <C <2%

0 ≤ V + W <6%

0 ≤ Nb + Zr ≤ 0.5%

0 ≤ Mo <8

Sn <1 0 ≤ B <0.006%

0 ≤ S + Se + Sb ≤ 0.008%

0 <Ca + Mg ≤ 0.020% the balance being iron and impurities resulting from the elaboration, the percentages of nickel, chromium, copper, cobalt being such that the alloy also satisfies the following conditions:

Co <Cu

Co <4% if Cr> 7.5%

Eq1> 28% with Eq1 = Ni + 1, 2Cr + (Cu / 5) Cr <7.5% if Ni> 32.5%,

and the manganese content further complying with the following conditions:

if Eq3> 205, Mn ≤ Ni - 27.5 + Cu - Cr

- if 180,5 ≤ Eq3 ≤ 205, Mn ≤ 4%

if Eq3 <180.5, Mn <2% with Eq3 = 6Ni - 2.5X + 4 (Cu + Co) and X = Cr + Mo + V + W + Si + AI

The proposed solution is a family of austenitic and ferromagnetic Fe-Ni-Cr-Cu alloys suitable for economical industrial production, by induction or arc furnace, having few expensive elements and offering high or original performances for several areas of applications that will be detailed later. It was never discovered until now an alloy family could satisfy all these properties. In addition, the use of the same alloy for very different applications (for example by satisfying at the same time the need for reduced dilatability, resistance to corrosion, magnetism and Curie point) makes it possible to produce a larger tonnage. , to have a greater experience of industrial production and therefore a more reliable alloy in terms of reproducibility of the properties.

In addition, the present inventors have found the ability of silicon, chromium and copper to mechanically and chemically strengthen the surface-oxidized protective layer and to make it very adherent. Thus the oxidized layer becomes very stable in the time of the heat treatment or the use in an oxidizing ambient atmosphere, very chemically stable with respect to external chemicals and very mechanically stable with respect to shocks and friction between metal parts during the cycle. industrial production.

In addition, this very stable oxide generally has a thin thickness of a few microns, depending on the heat treatment cycle used. This small thickness of oxide is particularly interesting in watchmaking, because it limits and calibrates at the same time the air gap between the stator and magnetic coil core, respectively leading to both a limitation of the energy consumed by the battery of the watch and a reduction in the industrial dispersion of watch engines.

The invention will now be described in more detail but in a nonlimiting manner and illustrated by examples.

The alloy according to the invention comprises, in% by weight, the contents defined below.

The nickel content is limited to 36%, preferably 35% by weight and more preferably 34%, or even 29%. Such a limitation makes it possible to strongly limit the cost of the grade. She permits also to have an electrical resistivity of at least 70μΩ.cm, or even at least 80μΩ.cm if the nickel content is less than 34%, which is one of the elements of a good magnetization dynamics (the two others being a small thickness of metal and a weak coercive field). For some applications, such as bimetallic manufacturing, it is preferred to maintain the nickel content at 30% or higher to ensure a high Curie point. The nickel content is at least 24% in order to guarantee the obtaining of an austenitic structure throughout the composition range according to the invention. The chromium content is greater than or equal to 0.02% because it requires a minimum of chromium to have the required corrosion resistance properties. Furthermore, when the nickel content is between 32.5 and 36%, the chromium content is limited to 7.5%, in order to limit the cost of all elements other than iron and silicon. These characteristics make it possible to improve the resistance to acidic aqueous corrosion, atmospheric corrosion and hot oxidation of the grade, since the formation of a very chemically stable superficial oxide is observed, which is also very adherent to the metal. In addition, the addition of these elements does not significantly degrade the other properties of use of the alloy, such as the Curie point or the saturation magnetization.

The copper content is greater than or equal to 0.1% and is limited to a content of 15% and preferably to a content of 10% (in order to limit the cost of all elements other than iron and silicon ), possibly substituted by cobalt. In addition to its impact on the corrosion resistance of the grade, copper significantly improves the adhesion of the oxidized layer forming hot to the surface of the alloy.

It is preferred that the grade does not contain cobalt because of its cost and for the same reason, if cobalt is present, it is necessary that its content be lower than that of copper. In addition, where chromium is present in excess of 7,5%, cobalt must be limited to not more than 4%, and preferably 2%, because we want to limit the cost of all elements other than iron and silicon

The addition of at least 0.02% of silicon makes it possible to significantly improve the mechanical wear resistance of the surface oxide layer. In addition, the silicon may be added up to 2% to the alloy according to the invention to participate in its deoxidation in the arc furnace, without harming the other properties of the alloy.

Moreover, the present inventors have found that the contents of nickel, chromium and copper must respect the following relation: Eq1> 28% with Eq1 = Ni + 1, 2Cr + (Cu / 5)

Indeed, the respect of this condition makes it possible to guarantee the austenitic character of the alloy, without which none of the properties of use of the alloy would be in conformity with the desired objectives and which would also prevent to have a good aptitude for the setting in shape. The manganese content is between 0.01 and 6% by weight, and preferably between 0.02 and 6% by weight, which makes it possible to obtain an alloy which transforms well under heat thanks to the formation of sulphides, without degrade the properties of use of the alloy, such as the Curie point or the saturation magnetization. In order to maintain saturation induction values Bs greater than 4000 G, it is preferred that the manganese content remain below 5%. More preferably, the manganese content is between 0.1 and 1% by weight. Moreover, in the presence of chromium, its effect on saturation induction is aggravated, hence the need to limit it as follows: Mn <Ni - 27.5 + Cu - Cr if Eq3> 205

Mn <4% if 180.5 <Eq3≤ 205

Mn <2% if Eq3 <180.5

with Eq3 = 6Ni - 2,5X + 4 (Cu + Co) and X = Cr + Mo + V + W + Si + AI

The alloy may also include addition elements such as carbon, titanium, aluminum, molybdenum, vanadium, tungsten, niobium, zirconium, tin, boron, sulfur, selenium, antimony, calcium or magnesium.

The carbon can be added to the alloy by up to 2% and preferably up to 1% to harden the alloy by carbide formation. However, when the application of the alloy requires a coercive field Hc of less than 125 mOe, the carbon content will be kept below 0.1% after development-solidification in ingot or slab because its presence strongly degrades this characteristic. In addition, in order to achieve this characteristic (Hc) and preserve it over time, a decarburizing heat treatment may be applied to the thin sheet in the final state in order to significantly reduce the percentage of carbon to less than 100 ppm, and preferably to less than 50ppm.

Titanium and aluminum can be added to the 3% cumulative alloy in order to harden the grade by precipitation of Ni ₃ (Ti ₁ Al) compounds. The addition of aluminum can also improve the weldability of the alloy on glass. However, during thermal treatments under reducing gas, it is desired to use cracked ammonia or a premix of nitrogen + hydrogen. Apart from this, the nitrogen combines as low temperature anneals in AIN or TiN type compounds, and it is therefore necessary to reduce the Al, Ti residual content to the lowest to ensure the compatibility between high magnetic performance and gas heat treatment comprising nitrogen. This point applies in particular to any application requiring high magnetic performance and involving annealing in an atmosphere containing nitrogen. In this case, the combined titanium and aluminum content is limited to 30 ppm and preferably 20 ppm.

Molybdenum can be added up to 8% to improve both the mechanical strength and the hot oxidation resistance of the alloy. It will be limited preferably to 4% to limit the cost of elements other than Fe and Si. Vanadium and tungsten may be added to the alloy at a cumulative height of 6%, in order to improve its toughness, and are added preference to less than 3% in order to limit the cost of all elements other than iron and silicon.

Niobium and zirconium can be added to the alloy at a cumulative height of 0.5% to improve its mechanical strength. Tin can be added to the alloy at a level of 1% partially substituted for chromium.

The boron may be added to the alloy according to the invention in amounts ranging from 2 to 60 ppm, and preferably from 5 to 10 ppm, in order to improve its cutability by formation of boron nitrides. Below this range, its effect is no longer observable, while this effect saturates above 60ppm.

Sulfur is an impurity present in the scrap used for the preparation of the alloy, but may also be added in amounts ranging from 5 to 80 ppm, and preferably from 10 to 30 ppm in order to also improve the cutability and machinability of the alloy by formation of manganese sulfide. We can substitute all or part of the sulfur by adding selenium and / or antimony.

When added as cutability additives, the combined sulfur and boron contents are preferably between 5 and 60 ppm and preferably these two elements are combined within their respective preferred range.

In the same way, it is possible to add to the alloy according to the invention calcium and magnesium with a cumulative height of 4 to 200 ppm to improve the cutability by formation of MgO or CaO type compounds, the broad range of Ca + Mg to solve the compromise between cutting ability and magnetic performance, since unlike certain sulfides (MnS ...) and nitrides (AIN ....) a reductive annealing at high temperature can not dissolve them in the end Manufacturing.

The rest of the composition consists of iron and unavoidable impurities from the elaboration. Among these, mention will be made more particularly of phosphorus, nitrogen and oxygen which are contained at a maximum height of 500 ppm. For some applications, it is necessary to limit the cumulative oxygen and nitrogen contents to 100 ppm in order to maintain the coercive field within the desired limits.

In general, the alloy according to the invention can be produced and manufactured in the form of a hot-rolled strip, then a cold strip before being annealed and then optionally cold-worked. One can also stop at the stage of the hot rolled strip.

The alloy according to the invention can also be used in the form of massive products, forged or not, bars or son from a hot rolling possibly completed with a drawing. The strips or alloy piece may be obtained by any suitable method, as known in the art can do.

Thus, the alloy according to the invention will preferably be melted in vacuum induction furnace ingots. The ingots can be forged between 1100 and

1300 ⁰ C, then hot rolled to a thickness of 2.5 mm, between 1000 and 1200 ⁰ C. It will then etch the strip hot and cold rolled to the required thickness.

When it is desired to develop a particular crystallographic structure, of the {100} <001> type, cold rolling is carried out with an overall degree of hardening of 90 to 99% in several passes without intermediate annealing between each pass.

At the end of the cold rolling, it is preferably annealed between 800 and 1100 ⁰ C for 1 hour to soften the band alloy and thus facilitate its cutting or subsequent shaping. But it can be even more advantageous to cut by punching, stamping at high speed in the hardened state at the end of cold rolling, especially if the metal has been optimized vis-à-vis this implementation by the elements mentioned above such as B, S, Ca, Mg, Se ...

After cutting or shaping, the parts obtained can advantageously be annealed at 1100 ° C. for 3 hours under purified H2 (dew point <-70 ° C.) in order, in particular, to optimize the magnetic properties of the alloy. On the other hand, this annealing can be quite useless if it is particularly desirable to obtain dilatation or curie point properties or corrosion resistance properties.

As has been seen previously, the alloys according to the invention can be produced in industrial annealing under any type of gas. The alloys according to the invention have potential applications in many fields. Preferred composition domains are thus defined, grouping together alloys that are more particularly adapted to a given application, which will be described in detail below.

Electromagnetic devices with self-regulation of temperature

In a first preferred embodiment, the percentages of nickel, chromium, copper, cobalt, molybdenum, manganese, vanadium, tungsten, silicon and aluminum are such that the alloy also satisfies the following conditions: 0.02 <Mn

Eq2> 0.95 with Eq2 = (Ni - 24) [0.18 + 0.08 (Cu + Co)] and Eq3 ≥ 161 and

Eq4 <10 with Eq4 = Cr-1.125 (Cu + Co) and Eq5 <13.6 with Eq5 = Cr-0.227 (Cu + Co) and Eq6> 150 with Eq6 = 6Ni -2.5X + 1, 3 (Co + Cu) and

Eq7> 150 with Eq7 = 6Ni - 5Cr + 4Cu and

This composition is more particularly adapted to the manufacture of electromagnetic devices with self-regulation of temperature. A soft ferromagnetic material has a permeability μ much higher than the permeability of the vacuum. When this material is subjected to a variable magnetic excitation in time, it generates many more magnetic losses before reaching a characteristic value known as the Curie point T _c when it exceeds this temperature beyond which the material No. is more ferromagnetic. In addition, the saturation magnetization of the material, its magnetic losses and therefore its generation of thermal power decreases as one approaches T _c . The temperature autoregulation is then performed around the Curie point of the alloy if the residual magnetic losses specific to any non-magnetic conductor are removed, ie the heat flow from the alloy is greater than the flow. of heat generated in magnetic losses. For this, it is sometimes necessary to attach to the alloy according to the invention a much better thermal conductor material such as aluminum or copper, responsible for evacuating paramagnetic losses and allowing, in particular, self-regulation of temperature in induction cooking applications where the heat of a heated container inadvertently vacuum would evacuate otherwise by natural convection.

This technique has been described in particular in the application patent

EP 1 455 622, where the temperature self-regulation is obtained by combining alloys at low T _c between 30 and 350 ⁰ C and at least 32.5% nickel, with an aluminum heat diffuser to remove the magnetic losses of the Fe-Ni-Cr alloy when it reaches Tc.

The main property of use therefore remains the functional Curie point which is sought between 30 ⁰ C and 400 ⁰ C for induction cooking, industrial induction heating for example of injectors nozzles, composite molds, reheating beverage foods, foods, medical products, blood and constituents, soft or organic materials etc.

It also seeks a minimum resistance to corrosion and oxidation since the alloys are often in contact with different media and / or constituents in industrial atmospheres. This requires a good chemical stability of the alloy resulting in a good resistance to aqueous corrosion, good resistance to salt spray corrosion and good mechanical stability (adhesion + wear resistance) of the oxidized layer of surface in hot and oxidizing atmosphere.

Furthermore, alloys having a coefficient of expansion between 20 and 100 ° C. greater than 4.10 ^"6 Z ⁰ C, or even greater than 7.10 ^{" 6} Z ⁰ C., are also preferably sought. to reduce the possible bimetal effect that may exist between the alloy and a conductor layer closely associated with the alloy by plating, seizing, welding, plasma deposition, etc.

On the other hand, there is no particular requirement on the magnetic properties and the coercive field can be very degraded. It is therefore possible to add significant proportions of carbon of the order of 2% at most and preferably less than 1%. It has long been known that carbon in large quantities puts the crystal lattice under strong stress and thus increases the exchange interaction between magnetic moments and therefore increases the Curie point, which further reduces the percentage of nickel. to keep the same level of point of

Curie and therefore the same temperature of self-regulation.

The application of temperature self-regulation is however not restricted to induction cooking of liquids and food solids, but is more generally intended for any domestic or industrial system using an electromagnetic inductor and at least one thermally active part on passage elements which must be momentarily heated without exceeding certain critical temperature.

By way of example, mention may be made of the injection of more or less viscous fluids, food or otherwise, to accelerate the production of portions of preheated material for tasting, or also as a pre-requisite before another industrial operation such as thermo bonding. -activated, the polymerization of plastics, composites etc ....

There is also the rapid and self-regulated surface heating of shaped molds for thermosetting composites (need to regulate the temperature between 200 and 350 ^° C. according to the type of composite) or thermoplastics (need to regulate the temperature between 150 and 250 ^° C. according to the type of composite).

There is also the self-regulated heating of a needle or insert made of Tc-coated low alloy, in the center of a malignant tumor (whose cells fear heat more than normal cells). Finally, there is the self-regulated heating of an extrusion, spinning, etc. matrix. to limit the thermal gradient in the part implemented through the die, thereby limiting internal stress, surface embrittlement, property gradient, structural inhomogeneities .... The alloys according to the invention as defined above allow to achieve all the required properties.

In particular, the inventors have found that the respect of the limit values of equations 2 to 7 makes it possible to guarantee both a saturation induction level at 20 ^° C. of greater than 0, and even greater than 1000 ^° C., for emitting heat. by magnetic losses, that a point of

Curie Tc> 30 ^° C.

In a more general way, and whatever the application according to the invention, it is found that by adapting the composition of the alloy, the value of each of the equations 2 to 7 can be modified so as to conform to to the limit value imposed in a particular application, and thus adjust the induction level, as well as the Tc value of the alloy in question.

Magnetic flux self-adjusting devices

In another preferred embodiment, the alloy may further be such that:

Ni <29% Co <2% 0.02 <Mn <2%

Eq2> 0.95 with Eq2 = (Ni - 24) [0.18 + 0.08 (Cu + Co)] and Eq3 ≥ 161 and

Eq4 <10 with Eq4 = Cr-1, 125 (Cu + Co) and

Eq5 <13.6 with Eq5 = Cr-0.227 (Cu + Co) and

Eq6 ≥ 150 with Eq6 = 6Ni -2.5X + 1, 3 (Co + Cu) and

Eq7 ≥ 160

This composition is more particularly adapted to the manufacture of self-regulating magnetic flux devices. The magnetic flux regulation of a device as a function of the ambient temperature is based on the decrease of the saturation magnetization with the temperature in the vicinity of the Curie point, with a rate of decay that is substantially constant and fairly high. This allows a flow bypass system to compensate for exactly the magnetization decay of the magnets by varying magnetic flux passage section ratios between magnet and compensating alloy and thus still provide the same magnetic flux in a given range. temperature.

This self-regulation of magnetic flux is most commonly performed around the ambient temperature, and in particular between 30 ^° C. and + 100 ^° C. There is therefore a need for different alloys which will have a Curie point Tc within this temperature range.

On the other hand, there is no particular requirement on the magnetic properties and in this case of application the coercive field can be very degraded compared to the limit of 10A / m corresponding to the performance potential of the new alloys according to the invention. As before, up to 2% carbon and preferably up to 1% carbon may be added.

Controlled expansion devices

In another preferred embodiment, the alloy may further be such that:

Ni <35%

0.02 <Mn C <0.5%

Eq2> 1

Eq3> 170

Eq4 <10 with Eq4 = Cr-1, 125 (Cu + Co) and

Eq5 <13.6 with Eq5 = Cr-0.227 (Cu + Co) and Eq6> 159

Eq7> 160 with Eq7 = 6Ni - 5Cr + 4Cu This composition is more particularly adapted to the manufacture of controlled expansion devices.

The term "controlled expansion alloy" means alloys with lower expansion coefficients than other metal alloys (0: 20-100> 10.10 ^"6 Z ⁰ C), ie typically 0: 20-100 < 10.10 ^"6 Z ⁰ C or 0: 20-300 <13.10 ^{" 6} Z ⁰ C.

They find use in applications requiring to maintain precise geometry and dimensions of some of these components depending on the temperature, or requiring a high thermal expansion compatibility between one of these active materials and a controlled expansion alloy, providing other functions (current conductor for example, or mechanical support). These applications have in common to subject the components temperature variations in a range from 20 to 450 ° C. For certain applications, it is thus necessary to be closely compatible in thermal expansion with another active material in the application (silicon, germanium, AsGa, SiC, sodium glasses, other glasses, stainless steel with small expansions, ceramics, etc. .). This close compatibility between another material and the alloy allows all of these two materials bonded by plating, welding, gluing, brazing, seizing ... to expand together without changing their shape, the odds evolving only predictably as a consequence of the general law of thermal expansion. Another advantage of this narrow expansion compatibility is that there are very few internal stresses of thermal origin between the two materials, which makes the thermal fatigue in operation of the bi-material negligible, thus considerably extending its service life.

One of these applications is the integrated circuit connectivity

(leadframe) where the alloy is tightly bound to the semiconductor to bring the electric current. It is thus necessary to use a controlled expansion alloy, to greatly limit thermal fatigue and premature deterioration of the interface. Another application is for mechanical support with low expansion in a predefined temperature range. For example, a video projector uses a multitude of small mirrors whose position must move as little as possible with the heating of the device that can bring the support of mirrors up to 400-450 ⁰ C locally.

Another application is the manufacture of transistor supports and housings, optoelectronic circuit semiconductors (AsGa for example), RX tubes, sealed glass bushings ...

In all these applications, the controlled expansion alloy is tightly bonded to a semiconductor or a glass or ceramic, and the expandability requirements can range from 4 to 5.10 ^"6 Z ⁰ C to 11.10 ^{~ 6} / ° C. One example is the support / strapping of large automotive roof windows

(opening or not), where the alloy must imperatively expand with the glue that binds them in the same way as the glass slab. We can also mention the low deformation support of ceramics such as piezoelectric PZTs used as an actuator in auto fuel injection.

It is also possible that the controlled expansion alloy provides only this function in the application, while being able to be shaped precisely by folding, stamping, stamping, spinning, mechanical or chemical machining (engraving ), welding, etc .: In this case, the mechanical part with precise dimensions made in the controlled expansion alloy has the advantage of expanding slightly and in a predefined manner over a wide temperature range. Thus the parts of an electron gun heat up under the effect of electrons, by offering them only certain holes to pass (calibration of the electron beam) which is the function of these parts: we therefore need dilating alloy as little as possible throughout the working temperature range, and having good fitness.

In addition to dilatability, good resistance to aqueous acid corrosion, good resistance to salt spray corrosion and good resistance to mechanical wear of the oxide layer are desirable properties. These properties are obtained with inexpensive industrial annealing (low dew or dew point) or in harsh environments without the need for additional protection.

These alloys therefore represent good alternatives to conventional FeNi alloys, while containing less nickel than these.

Current sensors, measuring transformers or magneto-harmonic sensors

In another preferred embodiment, the alloy may further be such that:

Cu <10% 0.02 <Mn C <0.1 Eq2> 1 Eq3> 170

Eq4 <10 with Eq4 = Cr-1.125 (Cu + Co) Eq5 <13.6 with Eq5 = Cr-0.227 (Cu + Co) Eq6> 159

Eq7> 160 with Eq7 = 6Ni - 5Cr + 4Cu

This composition is more particularly adapted to the manufacture of current sensors or measurement transformers.

Preferably, an aptitude is sought to obtain good magnetic performances under any type of non-oxidizing industrial atmosphere such as neutral gas, He, H2, N2, NH3, etc., which then makes it necessary to reduce the Titanium content as much as possible. preferably <30 ppm, preferably <20 ppm.

Current sensor or measurement transformer means the current detection or magnetic field detection devices with a threshold overrun (electronic differential circuit breaker) or current measurement, field (current transformer, voltage , energy meter, DC sensor). This type of application particularly requires a weak coercive field while the saturation magnetization may be low (4000 to 8000G to

20 ⁰ C) as for example in many cases of closed loop current sensor, or perhaps high (> 10 000G) as in the case of open loop current sensors.

The main magnitude of the application is the measurement accuracy which is strongly related to the coercive field of the alloy used, as well as in many cases the linearity BH of the magnetization curve or the hysteresis cycle: plus Hc is low, better is the measurement accuracy. For some applications, such as wideband frequency current transducers, a very low dynamic hysteresis is required to ensure good measurement accuracy at medium frequencies, which can be achieved by closed-loop structures operating at the same time. low induction, but also by choosing low Hc materials and high electrical resistivity.

In synthesis, a material adapted to these applications must have the following characteristics:

- Induction Bs at 20 ⁰ C from 4000G to more than 13000G depending on the application

- Hc <75 mOe (preferably <37 mOe) - Electrical resistivity p _e ι> 60μΩ.cm (preferably p _e ι> 70μΩ.cm).

In certain cases of applications, the linearity of the magnetization curve B-H is also sought up to the bend of the magnetization curve. This linearity is characterized by the Br / Bm ratio of the residual induction on an induction measured in the saturation approach zone. If Br / Bm <0.3 the linearity becomes exploitable in these specific applications with magnetic cores without localized air gap.

The alloys according to the invention make it possible to achieve all of these properties. The composition adapted to these applications is also suitable for the manufacture of magneto-harmonic sensors. In this application, a material with high permeability and low coercive field is subjected to the magnetic polarization greater or less of a semi-remanent magnetic material; the magnetization state of the latter (magnetized, demagnetized or partially magnetized) corresponds to an information or an alarm which is transmitted to the soft material through the polarization thereof. The soft material is excited at medium frequency by an external magnetic field, producing no, little or much of the fundamental harmonic emitted according to whether the soft material was subjected to respectively a semi-remanent demagnetized, partially magnetized or magnetized. Thus the detected harmonic amplitude is the image of the polarization level of the semi-remnant.

For example in a library, this device is slipped in the magnetic state in the jacket of each book stored. When borrowing, the book is saved and at the same time demagnetized to pass safely the security portal (no harmonic emission). If the book has not been demagnetized by the specific equipment, the high rate of harmonic emission triggers the start of the warning signal when passing to the output under the detection portal.

To react dynamically to such pulses requires a large magnetization dynamic ie a high electrical resistivity, a very small band thickness typically less than 50 .mu.m, and preferably less than 30 .mu.m, and a low coercive field, typically Hc less than 63 mOe, and preferably less than 25 mOe. The coercive field also controls the ^1st order the sensitivity of the magneto-harmonic sensor and will trigger it for a distance from the excitation antenna all the greater as Hc is weak. The coercive field is the most restrictive property for the compositional field which will have to be limited in copper for this reason.

In synthesis, a material adapted to these applications must have the following characteristics: - Hc <63 mθe (preferably <25 mOe) both to have a good sensitivity of the sensor to the field of excitation medium frequency and to limit the dynamic hysteresis (thus to promote the dynamics of magnetization) - Resistivity electric r _e ι> 60μΩ.cm (preferably r _e ι> 80μΩ.cm) to have a good dynamic response to the external excitation medium frequency.

The alloys according to the invention make it possible to achieve all of these properties.

Electromagnetic motors and actuators

In another preferred embodiment, the alloy may further be such that:

0.05% <Mn <2% C <0.1

Eq2> 1, 5

Eq3> 175

Eq4 <7 if Ni <32.5, or Eq4 <10 if Ni> 32.5

Eq5 ≤ 10.6 if Ni <32.5, or Eq5 <13.6 if Ni> 32.5 Eq6> 164

Eq7> 160 with Eq7 = 6Ni - 5Cr + 4Cu

This composition is particularly suitable for the manufacture of electromagnetic motors and actuators. Preferably, an aptitude is sought for obtaining good magnetic performances under any type of non-oxidizing industrial atmosphere such as neutral gas, He, H2, N2, NH3, etc., which then makes it necessary to reduce the Titanium content as much as possible, preferably <30 ppm, preferably <20 ppm.

The electromagnetic motors and actuators that can be manufactured according to the invention have a medium to high power density, a high precision of movement, a low dissipation and a low cost. This application will include all non-polarized electromagnetic devices comprising a moving part (rotor for a rotary system, motor, alternator, synchro-resolver, reluctant torque sensor, motor-wheel, etc., pallet or core for systems in translation tq engine linear, solenoid valve, injector, impulsive linear actuator type camless etc ..) made of soft magnetic material with high electrical resistivity and low magnetic losses, and a static part comprising a magnetic magnetic material.

The devices according to the invention have in particular the following characteristics:

- A small enough to very reduced space depending on the power transferred into the application, knowing that the higher the power of the actuator or sensor or motor, the higher it is important to have a high saturation material. This implies a saturation induction greater than 5000 G,

- low energy dissipation (or good energy efficiency) thanks to a high electrical resistivity (> 70μΩ.cm), a low Hc (<125 mOe), a fairly high permeability in direct current (> 5000μ ₀ ), - good placement accuracy of the moving part greatly reducing the phenomenon of unidirectional or rotational dynamic hysteresis (obtained with Hc <125 mOe, and preferably <75 mOe). This property is particularly important for variable reluctance torque sensors, for resolvers and resolvers and more generally for all rotating systems with low airlift reluctance.

In this type of application, the magnetic yokes can be made by stacking cut pieces at relatively low thicknesses.

(> 0.1mm, preferably 0.15mm) making it possible to limit as much as possible the macroscopic induced currents, the magnetic losses, the dynamic hysteresis phenomenon; in systems with magnetic stresses unidirectional (solenoid valves, electro-injection, Camless actuator, gas safety actuator, for example), a thick sheet or a wire shaped to the final cylinder head is used by stamping / forming / pressing / machining etc. before final annealing. In the case of devices with rotating magnetic fields (rotary systems for example) it is preferable that the alloy has an isotropy the best possible of its magnetic performance because otherwise it introduces oscillations of torque depending on the pitch (motors case) ), magnetic reluctance fluctuations as a function of the position of the moving part (in the case of the resolver-sync, the reluctant torque sensor, etc.). The problem is solved either by using rolling-annealing sequences that do not develop a crystallographic texture, or by developing a "planar" type texture, for example {100} <0vw> or {111} <uvw>.

In the case of a non-polarized electromagnetic safety actuator device, such as those used to prevent domestic gas leakage on gas heating systems (eg water heaters), low inrush currents are required and triggering of the device (and a small difference between these currents) which necessarily pass through weak coercive fields (see above) and low gaps between magnetic yoke and movable core of the actuator, but also by a low remanence to ensure release even with very small air gaps, to reduce the difference in switching and tripping currents, to reduce the dispersion of production performance of the device. In particular, it is sought in this case of EyBm application _3x <0.5 and preferably <0.3 (B _max induction for a magnetic field at least equal to 3H _C ).

The alloys according to the invention make it possible to achieve all of these properties. Stators for watch engines

In another preferred embodiment, the alloy may further be such that:

0.05% ≤ Mn ≤ 2% C <0.1

Co <1, 8%

O + N <0.01%

Eq2> 1, 5

Eq3> 175 Eq4 ≤ 7 if Ni ≤ 32.5, or Eq4 <10 if Ni> 32.5

Eq5 <10.6 if Ni <32.5, or Eq5 <13.6 if Ni> 32.5

Eq6> 164

Eq7> 160 with Eq7 = 6Ni - 5Cr + 4Cu the alloy also satisfying at least one of the following relationships: 0.0002 <B <0.002%

0.0008 ≤ S + Se + Sb ≤ 0.004%

0.001 ≤ Ca + Mg ≤ 0.015%

This composition is more particularly suited to the manufacture of stators for clockwork engines, in particular of the step-by-step type.

Preferably, an aptitude is sought for obtaining good magnetic performances under any type of non-oxidizing industrial atmosphere such as neutral gas, He, H2, N2, NH3, etc., which then forces the content to be reduced as much as possible. Titanium, preferably <30 ppm, preferably <20 ppm.

For this type of application, alloys are sought at a low cost while satisfying a certain number of properties.

First of all, a good cutability of the alloy strip is sought by punching, stamping or any other suitable method, allowing a low tool wear and a high rate of cutting. Indeed, the metal is delivered by the producer to the hardened or softened state in order to maintain sufficient mechanical hardness of the metal conducive to the cutability by stamping and high speed. Yet this hardness is not enough to achieve cutting hundreds of thousands of stator parts without significant burrs and without using the cutting die and especially the cutting punch to the point of re-sharpening or replacing it. To achieve this, it is also necessary to insert into the metal some fine inclusional distributions playing the role of "cut along the dotted line" during the process of cutting between punch and die. Moreover, these fine inclusions must be able to be eliminated during the subsequent high temperature annealing of optimization of the magnetic properties. This is why the alloys according to the invention intended for this application incorporate from 8 to 40 ppm of S, Se ₁ Sb and / or from 2 to 20 ppm and / or from 10 to 150 ppm of Ca, Mg.

It is then sought a saturation induction Bs which must be greater than 4000 G at 60 ⁰ C, and preferably less than 7000 G.

It also seeks to minimize the power consumption of the watch engine when it is used at its nominal power, that is when the magnetic alloys of the stator work near the magnetization elbow B-H of the material.

For this, for a stator thickness limited to a minimum of 0.4 mm below which the mechanical rigidity is no longer sufficient, the alloy must have an electrical resistivity of more than 70 .mu.m, and preferably greater than 80. μΩ.cm and a low coercive field Hc less than 125 mOe and preferably less than 75 mOe before mounting in the watch.

In addition, the power consumption of the watch should not increase significantly when the ambient temperature increases. Indeed, if the working magnetization decreases significantly when the temperature increases, then to always provide the minimum torque for the rotation of a half-turn of the rotor, the energy generator must provide much more energy to maintain the magnetization level of the stator and thus the motor torque applying to the rotor. Thus in the case of use of the watch in a hot atmosphere, the consumption will increase significantly. To control the power consumption when the ambient temperature increases, it is necessary that the saturation magnetization Js remains stable in the potential operating range of the watch, namely from -40 ^° C. to + 60 ° C., such a characteristic is systematically obtained when the Curie point of the Tc alloy is greater than or equal to 100 ^° C.

It also seeks a good resistance to corrosion. Indeed, the magnetic stator parts, once cut and passed to the magnetic performance optimization heat treatment, are stored, routed and mounted in the open air in watch movements. These assemblages are becoming more and more massive in countries where there is a great deal of atmospheric corrosion, especially of saline origin or due to atmospheric pollution (sulfur, chlorine, etc.).

Depending on the quality and life expectancy of the watch, the requirement of resistance to acid corrosion will be higher or lower. Indeed, the life of the watch does not exceed the time of significant degradation of the alloy of the stator by atmospheric corrosion. If it is a quality watchmaking engine entering renowned manufacturing areas such as "Swiss-made" or "Japan-made", the watch is made to last a few years and the alloy watch must not corrode significantly in this period of time. If it is a high-end watchmaking engine or transparent watch including visible engine parts, it should in principle operate without problems during the life of a person.

The different levels of resistance to corrosion can then be evaluated according to:

- low-end watch movement: minimum corrosion resistance with _max ^ox <5mA, - watch movement of Swiss-made or "Japan-made" quality: intermediate corrosion resistance with _max ^ox <3mA,

- watch movement visible in operation (transparent watch) or guaranteed for life: high performance corrosion resistance, with _max ^ox <1mA. Inductors or transformers for power electronics

In another preferred embodiment, the alloy may further be such that:

Cu <10% 0.02 <Mn

C <0.1 Eq2> 1, 5% Eq3> 189

Eq4 <4 if Ni <32.5, or Eq4 <7 if Ni> 32.5 Eq5 <4 if Ni <32.5, or Eq5 ≤ 7 if Ni> 32.5

Eq6> 173 Eq7> 185

This composition is more particularly suited to the manufacture of inductors or transformers for power electronics.

The magnetic circuits of the passive magnetic components used in power electronics or in any other medium-frequency energy conversion system (a few hundred Hz to a few hundred kHz) require the use of smoothing inductance or transformers which constitute often large parts of the power supplies.

In the dimensioning of these components, it is at the same time the saturation magnetization of the magnetic core but also the losses Joule-conductor and the magnetic losses generated and evacuated by the whole of the component which fix the accessible potential of reduction of the volume linked to the soft magnetic material used.

It follows that a good passive magnetic component magnetic core type storage inductor or smoothing, or power transformer must first have a high saturation induction at operating temperatures, which are typically around 100-120 ⁰ C. and search a saturation induction Bs ^{100 ° C} greater than or equal to 4000G, which corresponds to a saturation induction at 2O ⁰ C, Bs ^{20 ° c} which is greater than 8000G or else at a Curie point Tc of greater than or equal to 150 ^° C.

It must also have low magnetic losses at operating temperatures, which corresponds, for metal thicknesses of at most 50 .mu.m, to an electrical resistivity at 100.degree. C. greater than 60 .mu.m, and preferably greater than 100 .mu.m. cm and at a low dynamic hysteresis characterized by a coercive field Hc at 100 ⁰ C of less than 75 mOe and preferably less than 37.5 mOe. It is therefore imposed that the coercive field Hc at 20 ° C is less than or equal to 75 mOe, and preferably less than 37.5 mOe. It is indeed well known to those skilled in the art that Hc decreases with temperature in soft magnetic materials, when the temperature approaches the Curie point, and so we will obtain a fortiori performance at 100 ⁰ C if guaranteed them at 20 ⁰ C.

In addition, the residual losses of the alloys according to the invention can be compensated for by a much better ability to extract these losses due to the high thermal conduction of metal alloys and the very high fitness to shape and work of these yokes very ductile magnets and to easily install cooling circuits or give a complex shape to the magnetic circuit.

bimetallic

In another preferred embodiment, the alloy may further be such that:

Ni> 30% 0.02 <Mn

C <1%

Eq2> 1, 5

Eq3> 189

Eq4 <4 if Ni <32.5, or Eq4 <7 if Ni> 32.5 Eq5 <4 if Ni <32.5, or Eq5 <7 if Ni> 32.5

Eq6> 173 Eq7> 185

Eq8> 33 with Eq8 = Ni + Cu - 1, 5Cr

This composition is more particularly suitable for the manufacture of bimetallic strips.

In this application, a temperature variation can be transformed either in deformation of the bimetallic strip, or in elevation of the end of the bimetallic strip, the other end being held in position, or in force exerted by the free end of bimetal, thanks to the close connection of two materials in the form of a narrow and flat strip of different dilatabilities.

The bimetallic pieces can serve both as an overcurrent sensor through the electrical resistivity of the multilayer material and its deflection, temperature sensor through the deflection of the bimetal which then cuts an electrical circuit or thermomechanical actuator to through the force generated by the unbalanced expansion of the different components of bimetallic. In all cases, the bimetallic action passes through its deflection whose amplitude is proportional to the difference in expansion between the two external components of the bimetallic strip. The sensitivity of the bimetallic actuator will be all the greater as the expansion gap will be large for given band thicknesses and a given temperature difference.

Therefore sought a material having a mean coefficient of expansion between 20 ⁰ C and 100 ⁰ C α ₂ o-ioo which is less than or equal to 7.10 ^"6 Z ⁰ C and preferably less than or equal to ^{5.10" 6} / ° C and simultaneously an average coefficient of expansion α ₂ o- ₃ oo which is less than or equal to 10.10 ^"6 Z ⁰ C and preferably less than or equal to 8.10 ^{" 6} Z ⁰ C, to allow use over a wide temperature range.

Another important quantity when the heat source comes from the electric current flowing through the bimetallic strip, is the electrical resistivity p _e ι. Thus a bimetallic having a high average electrical resistivity will heat much more and will rise to a higher temperature than a bimetallic low electrical resistivity. This will result in either an arrow or deflection amplitude bimetallic in the same ratio, or a bimetallic-actuator force in the same ratios. In addition, the electrical resistivity is inversely proportional to the thermal conductivity, which in turn ensures the uniformization of the temperature and thus ensures the dynamics of the bimetallic response.

Thus research materials having an electrical resistivity at 2O ⁰ C - p _e i - greater than 75 μΩ.cm, preferably greater than δOμΩ.cm.

Furthermore, the addition of a third metal layer such as copper or nickel between the low and high dilatability layers allows different resistivity / conductivity trade-offs to be set without changing the dilatabilities.

In addition, it is necessary to have a material having a Curie point Tc greater than or equal to 160 ⁰ C, and preferably greater than 200 ⁰ C to maintain a good temperature stability of the expansion properties. To obtain this high Curie point, this low dilatability, and this high electrical resistivity, it is necessary for the alloys according to the invention to have more than 30% nickel and to respect the equation 8 defined by:

Eq8 =% Ni +% Cu - 1, 5% Cr> 33

Clocks cores of clockwork motors or electromagnetic relays with high sensitivity

In another preferred embodiment, the alloy may further be such that:

0.05% <Mn <2% C <0.1

Eq2> 2

Eq3> 195

Eq4 <2 if Ni <32.5, or Eq4 <6 if Ni> 32.5

Eq5 <2 if Ni <32.5, or Eq5 <6 if Ni> 32.5 Eq6> 180

Eq7> 190 This composition is more particularly adapted to the manufacture of watch motor coil cores or electromagnetic relays with high sensitivity.

Preferably, an aptitude is sought to obtain the good magnetic performances under any type of non-oxidizing industrial atmosphere such as neutral gas, He, H2, N2, NH3, etc., which then forces to reduce as much as possible the titanium content. preferably <30 ppm, preferably <20 ppm.

In a general objective of low power consumption of the watch, the magnetic field intended to magnetize the clock magnetic circuit must be produced with the minimum of electric current, that is to say with the maximum of turns of the excitation coil, this which results in the use of a very fine wire and magnetic core with a high magnetic flux to reduce the section of the core and to place a coil as large as possible. The magnetic alloy of the core must therefore necessarily offer a high magnetic saturation since the magnetic flux is the product of the magnetization by the section of the material. Alloys having a saturation induction Bs at 20 ^° C. which is greater than 10 000 G are therefore sought.

The alloy must also offer a low coercive field Hc and a high electrical resistivity to reduce magnetic losses, and thus limit the power consumption of the watch. Therefore, alloys having a coercive field Hc at 20 ^° C. which is less than 125 mOe and preferably less than 75 mOe and an electrical resistivity ρ _e ι that is greater than 60 μΩ.cm and preferably greater than 80 μΩ.cm are sought. In addition, the alloys according to the invention intended for this application preferably have good cutability and can therefore optionally incorporate from 8 to 40ppm of S, Se, Sb and / or from 2 to 20ppm and / or from 10 to 150 ppm of Ca, Mg.

The alloys according to the invention make it possible to achieve all of these properties. In a preferred embodiment, the alloys according to the invention have a saturation induction Bs greater than 13 000G and their composition must then comply with equation 9:

Eq9> 13000 with Eq9 = 1100 (Ni + Co / 3 + Cu / 3) - 1200Cr - 26000

Compositions suitable for the manufacture of clockwork motor cores are also suitable for the manufacture of high sensitivity electromagnetic relays.

An electromagnetic relay is a mechanical actuator with electrical control, where a generally massive magnetic yoke for reasons of ease and low cost of production / shaping, is closed by a piece of material and tilts on a breech leg end. The rocking position between "open" and "closed" results from the equilibrium between a mechanical force of return of a spring (placed outside the cylinder head and tending to open the magnetic circuit by rotating the mobile pallet around of the breech leg) and an electromagnetic force formed at rest of the sole magnetic attraction force of the magnetized yoke by a magnet on the pallet. At rest, the pallet closes the breech. A winding surrounds a leg of the cylinder head so that if an electric current from an external event and to be converted into a mechanical signal passes through it, there is added a magnetic force of repulsion of the pallet with respect to the cylinder head, which decreases the amplitude of the magnetic attraction force. Thus, depending on the amplitude of the electric current in the winding, the repulsive force can reach a level sufficient for the action of the spring to prevail by opening the relay and actuating a mechanical system. It is on this principle that electrical circuit breakers operate in particular.

For this type of relay to operate with a high sensitivity it is necessary that a small variation of current I in the coil causes a strong variation of the repulsion force and it must furthermore that this behavior be proportional over a sufficiently wide range of current in order to allow proper presetting of the relay. This amounts to defining a need for high permeability in a fairly linear induction range BH, centered on the operating point at rest of the relay, which corresponds to the magnetization of the relay polarized by the magnet and for a given bias frequency .

The more the material has a high saturation induction Bs, the higher the induction variation in the cylinder head under the effect of the current I, the greater the sensitivity of the relay and its high power with a given dynamic permeability. It also needs a saturation induction Bs at 20 ⁰ C higher than 10 000 G and preferably greater than 13,000 G, as well as a good dynamic magnetization obtained by a high electrical resistivity, p _e greater ι at ΘOμΩ.cm and preferably greater than 70μΩ.cm and a low coercive field Hc (at 20 ⁰ C) less than 125mOe and preferably less than 75mOe. Moreover, a minimum resistance to corrosion is required because the relays are often protected by non-hermetic packages, allowing the potentially hot, humid, oxidizing environment (Cl, S, etc.) to pass through the atmosphere while the non-oxidized state metal during its operation for years is important to ensure the reproducibility of trigger conditions by the non-drift of its magnetic performance. The ^ox _{max must} remain below 5 mA and preferably below 3 mA, or even below 1 mA.

Temperature measuring devices and temperature-limiting marking, non-contact

In another preferred embodiment, the alloy may further be such that:

Cu <10% 0.02 <Mn C <1%

Eq2> 0.4 Eq3> 140 Eq4 <10 Eq5 <13.6 Eq6> 140

Eq7> 125 This composition is more particularly suitable for the manufacture of temperature measuring devices or marking temperature overruns, without contact.

Magnetic parts of non-contact temperature measurement labels (real-time measurement, using a reversible magnetic phenomenon) or non-contact temperature measurement (posterior measurement, using an irreversible phenomenon but allowing a reset of the label at the end of the monitoring process) use at the same time very different materials, such as magnetically soft materials ("the alloy") and permanent magnet magnetic materials (MAP) in a stabilized configuration of temperature and magnetic fields surrounding. This temperature monitoring is, by the very principle of the label, carried out in the temperature range immediately below and around the Curie point of the soft magnetic alloy. In this application, it is possible, for example, to use a plate of

MAP section S1 secured to a plate of very high permeability material of section S ₂ , such as a thin FeNi alloy or an amorphous alloy, leaving a small air gap d between the two materials. The MAP material acts as a magnetic polarizer of the adjacent magnetically soft material. In addition, either on the other face of the MAP or between the MAP and the high permeability material, but separated from the material thereof by the air gap d, a third plate consisting of an alloy according to invention having a Curie point Tc.

When the ambient temperature approaches the Curie point Tc of the alloy according to the invention, it is less magnetized and the magnetic flux of the MAP closes for a larger part on the high-grade material. permeability which is polarized at a level of increasing magnetization and dependent on the ratio T / Tc.

By then exciting the high permeability material with a medium frequency field from a remote antenna, a magnetization variation ΔJ is produced around the bias magnetization Ji and the material will emit harmonics significantly, because has previously optimized J1 in this direction, via the choice of Si, S ₂ and d.

The functional Curie point which is sought is between -50 ^° C. and 400 ^° C., and in particular between -30 ^° C. and + 100 ° C. for many applications for monitoring the temperature of edible products such as the cold chain. the temperature of wine cellars, refrigerated and non-refrigerated stores and transports of perishable foodstuffs, containers of fish and meat, blood products and derivatives, stocks and shipments of thermo-perishable inedible organic substances such as plants, flowers, human specimens for implants or others, cell cultures and germs or bacteria, lots of polymers, macromolecules, etc. This Curie point is limited to a maximum of 400 ^° C. and is preferably between -30 ° C. and 100 ^° C.

A sufficiently weak coercive field (<75 mOe, and preferably <32.5 mOe) is required to obtain, on the one hand, a high sensitivity of the sensor to the medium-frequency excitation field, and on the other hand, a high dynamic range. the sensor by association with a high electrical resistivity (> ΘOμΩ.cm, and preferably> δOμΩ.cm) and preferably a small thickness of material. This restriction to low coercive fields makes it necessary to limit the percentage of copper to 10% maximum and preferably less than 6% in combination with a maximum nickel content of 34%.

It also seeks a minimum resistance to corrosion and oxidation since the alloys are often in contact with different media and / or constituents in industrial atmospheres. In these applications, it is often required a good chemical stability of the alloy resulting in a good resistance to aqueous corrosion (lox <5mA), good performance in the salt spray corrosion and good mechanical stability (adhesion + wear resistance) of the oxidized surface layer in a hot and oxidizing atmosphere.

The alloys according to the invention make it possible to achieve all of these properties.

Hyper-textured substrates for epitaxy

In another preferred embodiment, the alloy may further be such that: Mn <2%

If <1% Cu <10% Cr + Mo <18% C <0.1 Ti + Al ≤ 0.5%, the alloy also satisfies at least one of the following relationships:

0.0003 <B <0.004% 0.0003 <S + Se + Sb <0.008%

It is further preferred to add 0.003 to 0.5% niobium and / or zirconium.

These compositions are more particularly suitable for the manufacture of hyper-textured substrates for epitaxy.

Indeed, many applications require to grow thin layers of polycrystalline materials the most possible textures, that is to say with a texture if possible mono-component the highest possible.

One-component texture is not a non-random distribution of the crystallographic orientations of the poly-crystal, so that they are all located in a solid angle (from half-angle to the vertex ω) surrounding the ideal target orientation, noted [ hkl] (uvw) in Miller index, ω is called average texture disorientation and can have different values depending on whether it is measured in the rolling plane or out of the plane.

These deposited materials have particular physical properties, such as, for example, the superconductivity of Y-Ba-Cu-O type oxides. These properties are greatly improved by low density defects at the grain boundaries, which pass through small disorientations between adjacent crystals (role of an acute texture) and by a grain size of the order of a few tens of microns to reduce the density of defects with disorientation of identical texture. To obtain these highly textured polycrystalline deposits, one of the widely used methods is the epitaxial technique from a vapor or liquid phase, on a substrate itself which is hyper-textured with a mesh parameter fairly close to that of the deposited product. , a texture as mono-component and acute as possible, a good resistance to oxidation during any oxidative annealing required by the formation of deposited oxides, minimum mechanical strength to not creep during annealing and resist the implementation the final product (winding, winding, energizing, etc.)

The use of specific properties required for hyper-textured substrates are mainly including the presence of a surface fraction of twinning and other different orientations orientations centered within ^15th disorientation of cubic ideal orientation [10O] (OOI ), preferably less than 10%, and preferably less than 5% and a disorientation ω of the main cubic texture component {100} <001>: less than 10 ° and preferably less than 7 °. We also want an average dilatancy between 20 ⁰ C and

100 ⁰ C and an average dilatancy between 20 ⁰ C and 300 ⁰ C variables depending on the end applications. It may thus be necessary, when a substrate deposit is made hot, to compress the deposited layer when the product is returned to ambient. It must therefore be possible to choose an expansion set between 20 ^° C. and the deposition temperature at a very variable level according to the expansion / contraction of the deposited material. Finally, the Curie point is not limited for this property and in some superconducting applications it is even better that the substrate is as little magnetic as possible at the temperature of use ie 77K.

EXAMPLES

In the context of the present invention, the following abbreviations are used: B Inv. test according to the invention,

"Comp .: comparative test," NR: unrealized test, "CBS: sensitivity to salt spray corrosion,

UM: resistance to mechanical wear of the oxidized surface layer of alloys under oxidizing industrial atmosphere,

Bs ^{20 ° c} : saturation induction, measured at 20 ^° C. and expressed in Gauss.

Bs ^{60 C} (G): saturation induction, measured at 60 ^° C. and expressed in Gauss. "Tc: Curie point of the material, expressed in ° C.

"Hc: coercive field at 20 ^° C., measured in mOe." L ^ox : maximum current at imposed potential, measured in mA "Br / Bm: ratio of the Br residual induction on the induction measured in the approach zone at saturation Bm B 0C20-100: average coefficient of expansion (also called "dilatability") of the material, measured between 20 and 100 ° C and expressed in 10 ^ / ⁰ C and 0C20-300: average coefficient of expansion of the material, measured between 20 and 300 ⁰ C and expressed in 10 ^"6 / ° C and α _20- 77κ: average coefficient of expansion of the material, measured between 77K and 20 ⁰ C expressed in 10 ^{' 6} / ° C.

P _e i or p-elec: electrical resistivity at 20 ^° C., measured in μΩ.cm "μmax ^CC : maximum relative permeability in direct current, measured by comparison with the vacuum permeability μo (= 4π.1O ^{" 7} ) and therefore dimensionless and unit.

"ω: average textural disorientation, measured in ° (degree).

TESTS AND MEASURES

To test the alloys according to the invention, different alloy compositions were developed by vacuum induction melting, in the form of 50 kg ingots to the desired composition. The material is then forged between 1000 and 1200 ^° C., hot rolled between 1150 and 800 ^° C. to a thickness of 4.5 mm, etched by chemical means, cold rolled without intermediate annealing to 0 ^° C. , 6 mm. All the alloys are at least characterized at this stage after cutting into different samples such as those for dilatability, Tc, ^ox _m ax, Js and 25 x 36 mm diameter washers. Different tests are then carried out:

Resistance to salt spray corrosion, CBS

To measure CBS _1, an alloy sheet is immersed in a saline mist climate chamber made of a 95% humidity atmosphere, saturated with NaCl salt, for 24 hours. The sheets are then rinsed with alcohol and the pits of corrosion are observed. The density and the importance of the puncture are then noted with 3 levels of sensitivity:

0: not sensitive, -: a little sensitive

-: sensitive and

-: very sensitive to corrosion under salt spray.

Mechanical wear of the surface oxide layer, UM

To measure UM, the annealed metal is first annealed at a thickness of 0.6 mm, at a temperature of 1100 ° C., for 3 hours under pure hydrogen and water vapor such that the dew point is -30 ^° C. (simulation of an industrial annealing). Two sheets thus annealed are then stacked under a uniformly distributed mass giving a pressure equivalent to 1 kg for 10 cm ² . We then make 100 forward and backward sliding up to one half length of one sheet relative to the other then we observe the wear of the surfaces noted with 3 levels of wear resistance after examination of the surface of the metal:

- 0: low wear resistance,

- +: average resistance to mechanical wear and

- ++: very good resistance to mechanical wear.

Curie Point, Tc

Tc is measured by magnetic force at the Chevenard thermomagnetometer: the sample is heated at 100 ° C / h to 800 ° C and then cooled at the same rate to ambient temperature. The value of Tc retained is that corresponding to the operation of the thermogram at heating; the value of Tc is extrapolated on the origin axis (deviation = 0) from the tangent to the point of inflection of the magnetic force curve: f (T ^re ).

Resistance to aqueous acid corrosion IIO ^e X max Corrosion resistance of alloys in corrosive atmospheric media or in acidic aqueous media can be evaluated by measuring the maximum current obtained when immersing an alloy sample-plate in a bath of sulfuric acid 0.01 M and the alloy being connected by a conductor to another electrode-platinum plate, applying different voltage values. Different intensity values I are thus measured on the conductor connecting the two electrodes and the maximum value l ^ox _ma χ of I (U) is then determined.

By this test with imposed potential between plates, the evolution of the current in the conductor and in particular its maximum value gives a correct evaluation of the aptitude of the alloy to constitute a stable layer of oxide on its surface: plus the ^ox _my χ is low, the more the alloy is resistant to corrosion. Coefficients of dilatations dilatability)

The average coefficients of thermal expansion between 20 ⁰ C and a temperature T - noted <α ₂ o → τ ^> or convenience α2o-τ - are measured on a Chevenard dilatometer by comparing with a standard sample of Pyros (Fe-Ni from precise composition and dilation): the elongation variation Δl of a sample of initial length "I ₀ " is recorded as a function of the temperature T: Δl = f (T). The average dilatancy between 20 ^° C. and the temperature T ₁ is given by:

<α ₂₀ → τi> = expressed in 10 ^"6 Z ⁰ C

(millionth of relative elongation per degree).

Magnetic properties H _r , B _n u _ma «-

These properties are measured by flow-metric method according to IEC 404-6 standard, on the annealed washers: the hysteresis cycle plot makes it possible to determine the values of H _c , B _n μ _m ax ^Cc .

Example 1 - Magnetic Devices with Self-Regulation of Temperature

Several alloys were developed to a final thickness of 0.6 mm to characterize the properties of use. The alloys are made from 99.9% pure materials, melted in a vacuum induction furnace to a 50kg ingot. The ingot is forged between 1100 and 1300 ⁰ C, then hot rolled to a thickness of 2.5 mm, between 1000 and 1200 ⁰ C and then etched chemically. The strip is then cold rolled from the thickness of hot rolled to the thickness of 0.6mm, then annealed between 800 and

1100 ° C for 1 hour, then defatted, cut into different pieces or washers for measurements then annealed at 1100 ° C / 3h under purified H2 (dew point <-70 ° C). The shades tested include the elements mentioned in the following table, the balance being iron and unavoidable impurities.

Table 1 - Composition of test nuances

A series of tests are carried out to determine salt spray corrosion resistance, mechanical wear resistance, saturation induction, Curie point, acid corrosion resistance and dilatability values between 20 and 20. 100 ⁰ C.

The results of these tests are summarized in Table 2.

We see that part of the alloys according to the invention contains less than

30% Ni and can approach very close to the Curie point of Invar® (Fe-36% Ni: Tc = 250 ° C.), for example SV302mod1 (Tc = 199 ^° C.). The cost of alloy is thus substantially reduced by substituting a part of the nickel with copper; in addition, the resistance to aqueous, saline and oxidation corrosion is substantially improved by the joint additions of Cu ₁ Si, Cr.

Comparatively, if we do not put copper in a 30% Ni alloy, we obtain a Curie point as low as 40 ⁰ C and very poor resistance to acid corrosion.

It is also seen in Example SV298-1 that high dilatabilities can be obtained between 20 and 100 ^° C. (11.10 ^{° 6 °} C. in the example) by regulating the Ni, Cr and Cu contents adequately and no more than 30% Ni. The choice of composition adjusts the Curie point at the same time.

Example 2 - Magnetic flux self-adjusting devices

Several alloys were developed to a final thickness of 0.6 mm to characterize the properties of use. Alloys are made from 99.9% pure materials, melted in a vacuum induction furnace 50kg. The ingot is forged between 1100 and 1300 ⁰ C ₁ and then hot rolled to a thickness of 2.5 mm, between 1000 and 1200 ⁰ C and then etched chemically. The strip is then cold rolled from the thickness of hot rolled to the thickness of 0.6 mm, then annealed between 800 and 1100 ⁰ C for 1 hour, then degreased, cut into different pieces or washers for measurements then annealed at 1100 ° C / 3h under purified H2 (dew point <-70 ° C).

The shades tested include the elements mentioned in the following table, the balance being iron and unavoidable impurities.

Table 3 - Composition of test nuances

A series of tests are carried out to determine salt spray corrosion resistance, mechanical wear resistance, saturation induction, Curie point, acid corrosion resistance and dilatability values between 20 and 20. 100 ⁰ C.

The results of these tests are summarized in Table 4. It can be seen that most of the alloys according to the invention have Curie points of 30 ^° C. to about 100 ^° C. and this for alloys containing only 25 to 28% Ni. according to the desired resistance to corrosion and / or oxidation. The counter-example SV302mod-4 can not be suitable because it contains a percentage of manganese greater than 2%, and a wear resistance of the oxidized layer degraded despite the presence of silicon. The counter-examples SV297-1, NMHG-1 and NMGH-2 are not according to the invention because they do not respect equation 2. It is found that their Curie temperatures are below the limit value of 30 ^° C., unlike the examples according to the invention.

Several alloys were developed to a final thickness of 0.6 mm to characterize the properties of use. The alloys are made from 99.9% pure materials, melted in a vacuum induction furnace to a 50kg ingot. The ingot is forged between 1100 and 1300 ⁰ C, then hot rolled to a thickness of 2.5 mm, between 1000 and 1200 ⁰ C and then etched chemically. The strip is then cold rolled from the thickness of hot rolled to the thickness of 0.6mm, then annealed between 800 and

1100 ⁰ C for 1 hour, then defatted, cut into different pieces or washers for measurements then annealed at 1100 ° C / 3h under purified H2 (dew point <-70 ° C).

The dilatability measurements are carried out on a "Chevenard dilatometer" between -196 ° C. and 800 ^° C.

The shades tested include the elements mentioned in the following table, the balance being iron and unavoidable impurities. Table 5 - Composition of test nuances

A series of tests are carried out to determine the resistance values to salt spray corrosion, resistance to mechanical wear, Curie point, resistance to acid corrosion and dilatability between 20 and 100 ^° C. and between 20 and 100 ^° C. and 300 ^° C.

The results of these tests are summarized in Table 6. The first two tests correspond to very small dilations. The next nine have dilatabilities close to semiconductors such as Si, Ge, AsGa or SiC. The next seven have dilatations close to those of glasses. The following six are compatible with the use as a sealed tank for the transport of liquefied gas at 77K in LNG tankers. Table 6 - Test Results

In Example 36, compared to Invar®, it appears that substitute 3.5% Ni by 4% Cu and low levels of Si and Cr can maintain a dilatancy of less than 3.10 ^"6 Z ⁰ C between 20 and 100 ⁰ C, which is sufficient for many applications requiring to limit both the cost and the expansion towards the ambient as the shadow masks of the screens of cathode-ray tubes with high definition, the actuator supports of piezoelectric fuel automobile injector, the solid molds of aeronautical parts in carbon fiber and others, and also requiring that the material oxidizes little industrial annealing in a very weakly reducing atmosphere or even in an oxidizing atmosphere, and avoids using a protective gas atmosphere, thus simplifying the industrial implementation.

In example SV318-6, compared to N42, it appears that substitute 8% Ni by 6% Cu and 2% Cr and a low Si content allows maintain a dilatability lower than or equal to 6.10 ^"6 Z ⁰ C between 20 and 300 ⁰ C ₁ and even an equivalent dilatancy between 20 and 100 ⁰ C which is sufficient for most applications requiring to limit both the cost and the expansion in contact with semiconductor materials in a restricted temperature range of 100 to 300 ⁰ C above ambient as the integrated circuit supports.

In the examples SV304-4 or TD561-3 of this table, compared to the N426 used for its compatibility in dilation with the glasses of type Sb sodium glasses, it appears that substitute 14% Ni by 7 to 10% Cu and low levels Si and Cr make it possible to maintain a dilatability of the order of 7 × 10 ^-6 Z ⁰ C between 20 and 100 ^° C. and of 11.5 × 10 ^{-6 °} C. between 20 and 300 ° C., which is sufficient for many applications. application requiring to limit both the cost and the expansion in contact with certain glasses, alumina, Beryllium oxide, certain semiconductors such as I ¹ AsGa, etc. in a restricted range temperature of 100 to 300 ⁰ C above the ambient.

In the TD521-4 example of this table, compared to the N485, it appears that substitute 20% Ni by 6% Cu and less than 2% Cr and a low Si content makes it possible to maintain a dilatability of the order 9.5 × 10. ^"6 Z ⁰ C between 20 and 100 ° C and 11, 9.10 ^'6 Z ⁰ C between 20 and 300 ° C, which is sufficient for many applications requiring limiting both the cost and expansion in contact these very dilatable glasses, ZrO2, forsterite, etc. in a restricted temperature range of 100 to 300 ⁰ C above the ambient.

In the LNG carriers, we need a very low dilatability between

-196 ° C (gas liquefaction temperature) and ambient so that the giant containers of the liquid gas resist the destructive forces of expansion, especially the triple seals of the containers. It appears on the last examples of the table that substitute 3 to 6% Ni by 3 to 10% Cu and low levels of Si and Cr can maintain a dilatability of the order 3 to 3.5.10 ^"6 Z ⁰ C between - 196 ° C and 20 ⁰ C, which is sufficient for this application requiring to limit both the cost and the expansion of the superstructure between the liquefied gas at -196 ° C on one side, and the ambient temperature on the other face. Example 4 - Current Sensors and Measuring Transformers

Several alloys have been developed to the final thickness of 0.6 mm to characterize the properties of use. The alloys are made from 99.9% pure materials, melted in a vacuum induction furnace to a 50kg ingot. The ingot is forged between 1100 and 1300 ⁰ C, then hot rolled to a thickness of 2.5 mm, between 1000 and 1200 ⁰ C and then etched chemically. The strip is then cold rolled without intermediate annealing from the thickness of hot rolled to the thickness of 0.6 mm, then cut into different pieces or washers for measurements (see previously the different types of characterization used) before degreasing then annealed at 1100 ^° C. for 3 hours under purified H2 (dew point <-70 ° C.).

The shades tested include the elements mentioned in the following table, the balance being iron and unavoidable impurities. Table 7 - Composition of test nuances

A series of tests are carried out to determine the values of resistance to salt spray corrosion, resistance to mechanical wear, saturation induction at 20 ^° C., rectangularity of the hysteresis cycle to 2O ⁰ C, coercive field at 20 ⁰ C ₁ of electrical resistivity at 20 ⁰ C and acid corrosion resistance.

The results of these tests are summarized in Table 8.

It is observed that alloys with more than 10% Cu have very high coercive fields of 200 to 40OmOe incompatible with a measurement transformer type application.

The alloy SV330-4 is particularly economical with its 28% Ni and 3% Cu, with a very low Hc of 19mOe allowing a high accuracy of the transformer of measurement, on the other hand its low saturation (4430G) restricts it to applications towards the ambient temperature.

In another example of the invention, the SV330-6 alloy is nearly as economical with 28% Ni and 7% Cu and allows good closed-loop current sensor accuracy due to Hc = 33mOe; moreover its higher saturation (6800G) makes it much more stable in temperature and will allow operation of the measuring transformer up to 70 ⁰ C. In a last example, the SV317-5 alloy with high saturation (11540G) and low coercive field (34mOe) allows the realization of open loop current sensor of high precision, and economically (34% Ni) while ensuring good resistance to corrosion in many environments thanks to the conjunction of 2% Cr and 4% Cu associated with silicon.

Example S - Magneto-harmonic sensors

Several alloys have been developed up to a final thickness of 0.04 mm in order to characterize the properties of use. The alloys are made from 99.9% pure materials, melted in a vacuum induction furnace to a 50kg ingot. The ingot is forged between 1100 and 1300 ⁰ C ₁ and then hot rolled to a thickness of 2.5 mm, between 1000 and 1200 ⁰ C and then etched chemically. The strip is then cold rolled from the thickness of hot rolled to the thickness of 0.6 mm, then annealed between 800 and 1100 ⁰ C for 1 hour, then rolled to the final thickness of 40 .mu.m and then degreased, cut into different pieces or cores wound for measurement then annealed at 1100 ⁰ C for 3 hours under purified H2 (dew point <-70 ^° C.).

The shades tested include the elements mentioned in the following table, the balance being iron and unavoidable impurities.

Table 9 - Composition of test nuances

A series of tests are carried out to determine the values of resistance to salt spray corrosion, resistance to mechanical wear, saturation induction at 20 ⁰ C, coercive field at 2O ⁰ C, electrical resistivity at 20 ⁰ C and acid corrosion resistance.

The results of these tests are shown in Table 10. Table 10 - Test results

The example of the invention SV323-6 has a corrosion resistance in a very improved aqueous medium and the sensitivity of the sensor is excellent (Hc = 15mθe). In the SV306-4 example, the nickel content is lowered to 28% while the resistance to corrosion, salt spray corrosion, oxidation in a hot atmosphere and oxidizing are all excellent as well as the sensitivity of the sensor (Hc = 18mθe): this is allowed thanks to an optimization of the relative compositions in Ni ₁ Cr, Cu, Mn and Si. The cost of the sensor can be further lowered substantially in the example SV289-4 with only 26.5% Ni thanks to a strong presence of copper (5.6%) to maintain good resistance to corrosion and oxidation, and a very good sensitivity of the sensor (Hc = 31mθe).

Example 6 - Electromagnetic motors and actuators

Several alloys have been developed to the final thickness of 0.6 mm to characterize the properties of use. The alloys are made from 99.9% pure materials, melted in a vacuum induction furnace to a 50kg ingot. The ingot is forged between 1100 and 1300 ° C, then hot rolled to a thickness of 2.5 mm, between 1000 and 1200 ⁰ C and chemically etched. The strip is then cold rolled without intermediate annealing since the laminate thickness to warm up the thickness of 0.6mm, and cut into various pieces or washers for measurements before degreasing and then annealed at 1100 ⁰ C for 3 hours with purified H 2 (dew point <- 7O ⁰ VS).

The shades tested include the elements mentioned in the following table, the balance being iron and unavoidable impurities.

Table 11 - Composition of test nuances

A series of tests are carried out to determine the values of resistance to salt spray corrosion, resistance to mechanical wear, saturation induction at 20 ^° C., coercive field at 20 ^° C., electrical resistivity at 20 ^° C. ⁰ C and resistance to acid corrosion.

The results of these tests are shown in Table 12. It can be seen that the properties of sensitivity to salt spray corrosion and mechanical wear resistance of the oxidized surface layer are always good provided that the Cr, Si minima and Cu are respected. Table 12 - Test Results

Many alloys with various compositions of 28 to 34% of nickel make it possible to obtain magnetic saturations of 5000 to 12 000G, and electrical resistivities of 80 to 90μΩ.cm, while maintaining low coercive fields and corrosive behaviors. varied according to the specific need of the application.

In counter-example the SV292-4mod alloy does not check the equation 2, which results in too low saturation (4800G) related to an insufficient% Cu with respect to the nickel content. In another counter-example the alloy SV304-2mod does not verify the invention since its saturation is much too low (4080G instead of the minimum of 5000G), which is due to its too high manganese content.

TD560-8 alloy has 35% Ni and high saturation. Its permeability μmax was measured along the 0 °, 45 ° and 90 ° directions with respect to the rolling direction. We obtain respectively 19000, 17200 and 17600, which shows that the alloy is almost perfectly isotropic thanks to the succession of high rolling and final annealing at high temperature. By this property the magnetic flux will circulate isotropically and will not favor certain directions of the sheet, frequent origin of fluctuation of electromagnetic torque in the electrical machines. The alloys according to the invention therefore also have the property, through cold rolling and appropriate annealing, to be able to present if necessary a good isotropy of the magnetic properties.

It is also observed that the alloys according to the invention have a low remanence (rectangularity of the hysteresis cycle Br / Bm <0.3) which allows either to demagnetize largely naturally as soon as the excitation is cut off ("defluxing "Natural"), or not to be sensitive to disturbing parasitic fields (superimposed fields, very strong and very fugitive overcurrent that saturates the material for a very short time). It is noted in particular that it is advantageous to lower the% nickel and the chromium to lower the rectangularity Br / Bm to very low values such as 0.17 on alloys TD560-1, 3 and 5 containing a minimum of% Cr, 28 to 32% Ni and 10% Cu.

Example 7 - Stators for watch engines Several alloys were developed up to the final thickness of 0.6 mm in order to characterize the properties of use. The alloys are made from 99.9% pure materials, melted in a vacuum induction furnace to a 50kg ingot. The ingot is forged between 1100 and 1300 ⁰ C, then hot rolled to a thickness of 2.5 mm, between 1000 and 1200 ⁰ C and then etched chemically. The strip is then cold rolled without intermediate annealing from the thickness of hot rolled to the thickness of 0.6 mm, then cut into different parts or washers for measurements before degreasing and then annealed at 1100 ⁰ C for 3 hours under Purified H2 (dew point <-70 ° C). The shades tested include the elements mentioned in the following table, the balance being iron and unavoidable impurities.

The Curie point is determined by a round trip of the thermomagnetometer to a temperature of 800 ^° C.

A series of tests are also performed to determine the resistance values for salt spray corrosion, resistance to mechanical wear, electrical resistivity at 20 ^° C., Curie point, the coercive field at 20 ^° C., saturation induction at 20 ^° C. and saturation induction at 60 ^° C.

The results of these tests are summarized in Table 14.

Example 8 - Inductance and transformer for power electronics Several alloys were developed up to a final thickness of 0.6 mm to characterize the properties of use. The alloys are made from 99.9% pure materials, melted in a vacuum induction furnace to a 50kg ingot. The ingot is forged between 1100 and 1300 ⁰ C, then hot rolled to a thickness of 2.5 mm, between 1000 and 1200 ⁰ C and then etched chemically. The strip is then cold rolled from the thickness of hot rolled to the thickness of 0.6 mm, then annealed at 800 to 1100 ⁰ C for 1 hour, then degreased, cold rolled to the thickness 0.05mm, sheared, coated with a mineral insulator to avoid the bonding of the sires during the annealing and wound into torus diameters 30x20mm, height 20mm, then annealed at 1100 ° C / 3h under purified H2 (dew point <- 70 ° C).

The shades tested include the elements mentioned in the following table, the balance being iron and unavoidable impurities. Table 15 - Composition of test nuances

A series of tests is carried out to determine the values of saturation induction at 20 ^° C., Curie point, coercive field at 20 ^° C., electrical resistivity at 20 ^° C. and acid corrosion resistance.

The results of these tests are summarized in Table 16.

Table 16 - Test Results

It is seen that all the alloys according to the invention have at least 80μΩ.cm electrical resistivity at 20 ° C and a coercive force of less than 75mOe, and generally less than 41mOe at ^20c C: these performance combined with low Thickness and good inter-turn insulation guarantee low magnetic losses, all the more permissible in these magnetic cores of passive magnetic components that their good thermal conduction makes it possible to easily extract these magnetic losses.

It can be seen in the counterexamples SV301mod-1, SV292-1 and TC768 that the balance between% Ni and% Cu must be well ensured in order for the saturation to be sufficient, ie for the dimensioning of the magnetic circuit to lead to a sufficiently interesting volume with respect to ferrites.

Example 9 - Bilames Several alloys were developed up to the final thickness of 0.6 mm in order to characterize the properties of use. The alloys are made from 99.9% pure materials, melted in a vacuum induction furnace to a 50kg ingot. The ingot is forged between 1100 and 1300 ⁰ C, then hot rolled to a thickness of 2.5 mm, between 1000 and 1200 ⁰ C and then etched chemically. The strip is then cold rolled to a thickness of 0.6 mm, then annealed at 800 to 1100 ^° C. for 1 hour, then degreased, cut into different pieces or washers for measurements and then annealed at 1100 ° C. for 3 hours under purified H2. (dew point <-70 ° C).

The shades tested include the elements mentioned in the following table, the balance being iron and unavoidable impurities. Table 17 - Composition of test nuances

A series of tests is carried out to determine the values of resistance to salt spray corrosion, resistance to mechanical wear, Curie point, electrical resistivity at 20 ^° C., coefficient of expansion between 20 and 200 ^° C. and between 20 and 300 ^° C.

The results of these tests are shown in Table 18. Table 18 - Test results

Example 10 - Cores of clockwork motor coils and electromagnetic relay with high sensitivity

Several alloys have been developed to the final thickness of 0.6 mm to characterize the properties of use. The alloys are made from 99.9% pure materials, melted in a vacuum induction furnace to a 50kg ingot. The ingot is forged between 1100 and 1300 ⁰ C, then hot rolled to a thickness of 2.5 mm, between 1000 and 1200 ⁰ C and then etched chemically. The strip is then cold rolled without intermediate annealing from the thickness of hot rolled to the thickness of 0.6 mm, then cut into different parts or washers for measurements before degreasing and then annealed at 1100 ⁰ C for 3 hours under Purified H2 (dew point <-70 ° C).

The shades tested include the elements mentioned in the following table, the balance being iron and unavoidable impurities.

Table 19 - Composition of test nuances

A series of tests was performed to determine the resistance values to corrosion in salt spray resistance to mechanical wear, electrical resistivity at 20 ⁰ C for ₁ Curie point of saturation induction at 20 ⁰ C ₁ coercive field at 2O ⁰ C and acid corrosion resistance. The results of these tests are summarized in Table 20.

It can be seen that a saturation of 10 000 G at 20 ^° C. with only 30% Ni and a saturation of 13 000 G at 20 ^° C. with only 34% Ni can be obtained.

These performances are quite interesting and innovative, in addition to the properties of good resistance to corrosion and mechanical wear of the oxidized layer.

Table 20 - Test Results

Example 11 - Devices for measuring temperature and temperature-limiting marking, without contact

Several alloys were developed to a final thickness of 0.6 mm to characterize the properties of use. The alloys are made from 99.9% pure materials, melted in a vacuum induction furnace to a 50kg ingot. The ingot is forged between 1100 and 1300 ⁰ C, then hot rolled to a thickness of 2.5 mm, between 1000 and 1200 ⁰ C and then etched chemically. The strip is then cold rolled from the thickness of hot rolled to the thickness of 0.6 mm, then annealed between 800 and 1100 ⁰ C for 1 hour, then degreased, cut into different parts or washers for measurements ( see previously the different types of characterization used) and then annealed at 1100 ^° C. for 3 hours under purified H2 (dew point <-70 ° C.).

The shades tested include the elements mentioned in the following table, the balance being iron and unavoidable impurities.

Table 21 - Composition of test nuances

A series of tests are carried out to determine the values of resistance to salt spray corrosion, resistance to mechanical wear, saturation induction at 20 ^° C., Curie point, coercive field at 20 ^° C. and resistance to acid corrosion.

The results of these tests are summarized in Table 22. Table 22 - Test Results

It is noted that the counterexample does not check equation 1, which means that the alloy is not totally austenitic. The non-austenitic character of the alloy does not make it possible to achieve the required coercive field values.

Example 12 - Hyper-textured Substrates for Epitaxy

Several alloys have been developed up to the final thickness of 0.1 mm in order to characterize their properties of use. The alloys are made from 99.9% pure materials, melted in a vacuum induction furnace to a 50kg ingot. The ingot is forged between 1100 and 1300 ⁰ C, then hot rolled to a thickness of 5mm, between 1000 and 1200 ⁰ C and chemically etched. The strip is then cold rolled to a thickness of 0.1 mm without intermediate annealing, and then mechanically polished with abrasive polishing felt to a very fine polishing grain of the order of one micron. The metal is then annealed between 800 and 1100 ⁰ C for 1 hour, then cut into different pieces for measurements of pole figures by RX to evaluate the type and intensity of the texture obtained.

The shades tested include the elements mentioned in the following table, the balance being iron and unavoidable impurities. Table 23 - Composition of test nuances

A series of tests are carried out to determine the values of resistance to salt spray corrosion, resistance to mechanical wear, Curie point, resistance to acid corrosion, dilatability between 20 and 300 ^° C., rate of of twinning and mean texture disorientation.

The results of these tests are summarized in Table 24.

Table 24 - Test Results

It can be seen that the alloys according to the invention have a high ability to cubic texturing {100] <001> with a low macle level (<10%) and a low texture average misorientation ω (<10 °), a strong resistance to mechanical wear of the oxidized layer in a degraded operating or annealing atmosphere by the addition of minimum levels of Cr, Si and Cu, and variable dilatabilities in a wide range to meet most needs of substrate deposition dilation for epitaxy.

Claims

1. Iron-nickel-chromium-copper austenitic alloy whose composition comprises in% by weight:

24% <Ni <36%

Cr> 0.02%

Cu> 0.1%

Cu + Co≤ 15% 0.01 ≤Mn <6%

0.02 ≤ Si <2% 0 <Al + Ti <3%

0 ≤ C ≤ 2% 0 <V + W <6% O≤Nb + Zr≤O.5%

0 ≤ Mo ≤ 8

Sn <1

0 ≤ B ≤ 0.006% 0 ≤ S + Se + Sb <0.008% 0 ≤ Ca + Mg ≤ 0.020% the rest being iron and impurities resulting from the elaboration, the percentages of nickel, chromium, copper, cobalt being such that the alloy also satisfies the following conditions: Co <Cu Co <4% if Cr> 7.5%

Eq1> 28% with Eq1 = Ni + 1, 2Cr + (Cu / 5) Cr <7.5% if Ni> 32.5%,

and the manganese content further complying with the following conditions: - siEq3> 205, Mn ≤ Ni -27.5 + Cu -cr

- if 180,5 <Eq3 <205, Mn ≤ 4%

- if Eq3 <180.5, Mn ≤ 2% with Eq3 = 6Ni - 2.5X + 4 (Cu + Co) and X = Cr + Mo + V + W + Si + AI

2. An alloy according to claim 1, characterized in that the percentages of nickel, chromium, copper, cobalt, molybdenum, manganese, vanadium, tungsten, silicon and aluminum are such that the alloy also satisfies the following conditions: 0.02 ≤ Mn

Eq2> 0.95 with Eq2 = (Ni - 24) [0, 18 + 0.08 (Cu + Co)] Eq3> 161

Eq4 <10 with Eq4 = Cr-1, 125 (Cu + Co) Eq5 <13.6 with Eq5 = Cr-0.227 (Cu + Co) Eq6> 150 with Eq6 = 6Ni -2.5X + 1, 3 (Co + Cu)

Eq7> 150 with Eq7 = 6Ni - 5Cr + 4Cu

3. Use of an alloy according to claim 2 for the manufacture of electromagnetic devices with self-regulation of temperature.

An electromagnetic self-regulating temperature device comprising an alloy according to claim 2.

The alloy of claim 1, further characterized in that: Ni <29%

Co <2% 0.02 <Mn <2%

Eq2> 0.95 with Eq2 = (Ni-24) [0.18 + 0.08 (Cu + Co)] Eq3> 161 Eq4 <10 with Eq4 = Cr-1, 125 (Cu + Co)

Eq5 <13.6 with Eq5 = Cr-0.227 (Cu + Co)

Eq6> 150 with Eq6 = 6Ni -2.5X + 1, 3 (Co + Cu)

Eq7> 160 with Eq7 = 6Ni - 5Cr + 4Cu

6. Use of an alloy according to claim 5 for the manufacture of self-regulating magnetic flux devices.

7. Self-regulating magnetic flux device comprising an alloy according to claim 5.

An alloy according to claim 2, further characterized in that:

Ni <35% C ≤ 0.5% Eq2> 1 Eq3> 170

Eq6> 159 Eq7> 160

9. Use of an alloy according to claim 8 for the manufacture of controlled expansion devices.

10. Controlled expansion device comprising an alloy according to claim 8.

An alloy according to claim 2, further characterized in that:

Cu <10%

C <0.1

Eq 2> 1

Eq3> 170 Eq6> 159

EQ7> 160

12. Use of an alloy according to claim 11, for the manufacture of current sensors, measurement transformers or magneto-harmonic sensors.

Magneto-harmonic current sensors, measurement transformers or magnet sensors comprising an alloy according to claim 11.

An alloy according to claim 2, further characterized in that:

0.05% <Mn <2%

C <0.1

Eq2> 1, 5

Eq3> 175 Eq4 <7 if Ni <32.5,

EQ5 <10,6siNi <32.5, Eq6> 164 Eq7> 160

15. Use of an alloy according to claim 14 for the manufacture of electromagnetic motors and actuators.

An electromagnetic motor and actuator comprising an alloy according to claim 14.

An alloy according to claim 14, further characterized in that:

Co <1, 8%

O + N ≤ O.01% the alloy further satisfying at least one of the following relationships:

0.0002 <B <0.002% 0.0008 ≤ S + Se + Sb ≤ 0.004%

0.001 ≤ Ca + Mg ≤ 0.015%

18. Use of an alloy according to claim 17 for the manufacture of stators for clockwork engines.

19. Stator for a clockwork motor comprising an alloy according to claim 17.

20. An alloy according to claim 11, further characterized in that: Eq2> 1.5%

Eq3> 189

Eq4 ≤ 4 if Ni ≤ 32.5, or Eq4 ≤ 7 if Ni> 32.5 Eq5 ≤ 4 if Ni ≤ 32.5, or Eq5 ≤ 7 if Ni> 32.5 Eq6> 173 Eq7> 185

21. Use of an alloy according to claim 20, for the manufacture of inductances or transformers for power electronics.

22. Inductor or transformer for power electronics comprising an alloy according to claim 20.

23. An alloy according to claim 2, further characterized in that:

Ni> 30% C <1% Eq2> 1, 5 Eq3> 189

Eq4 <4 if Ni ≤ 32.5, or Eq4 ≤ 7 if Ni> 32.5 Eq5 ≤ 4 if Ni ≤ 32.5, or Eq5 <7 if Ni> 32.5 Eq6> 173 Eq7> 185 Eq8> 33 with Eq8 = Ni + Cu - 1.5Cr

24. Use of an alloy according to claim 23 for the production of bimetallic strips.

Bilam comprising an alloy according to claim 23.

26. An alloy according to claim 14, further characterized in that:

Eq2> 2 Eq3> 195 Eq4 ≤ 2 if Ni ≤ 32.5, or Eq4 ≤ 6 if Ni> 32.5

Eq5 ≤ 2 if Ni ≤ 32.5, or Eq5 ≤ 6 if Ni> 32.5 Eq6> 180 Eq7> 190

An alloy according to claim 26, further characterized in that:

Eq9> 13000 with Eq9 = 1100 (Ni + Co / 3 + Cu / 3) - 1200Cr - 26000

28. Use of an alloy according to either of claims 26 or 27, for the manufacture of cores of clockwork motor coils or electromagnetic relays with high sensitivity.

29. A clockwork motor coil core or a high sensitivity electromagnetic relay comprising an alloy according to claim 26 or 27.

An alloy according to claim 1, further characterized in that:

Cu <10% 0.02 <Mn C <1% Eq2> 0.4 with Eq2 = (Ni - 24) [0.18 + 0.08 (Cu + Co)]

Eq3> 140

Eq4 <10 with Eq4 = Cr-1, 125 (Cu + Co)

Eq5 ≤ 13.6 with Eq5 = Cr-0.227 (Cu + Co)

Eq6> 140 with Eq6 = 6Ni -2.5X + 1, 3 (Co + Cu) Eq7> 125 with Eq7 = 6Ni - 5Cr + 4Cu

31. Use of an alloy according to claim 30, for the manufacture of temperature measuring devices or temperature-limiting marking, without contact.

Apparatus for temperature measurement or temperature-limiting marking, without contact, comprising an alloy according to claim 30.

An alloy according to claim 1, further characterized in that:

Mn <2%

If <1%

Cu ≤ 10%

Cr + Mo <18% C <0.1

Ti + Al <0.5% the alloy further satisfying at least one of the following relationships:

0.0003 <B <0.004%

0.0003 <S + Se + Sb <0.008%

The alloy of claim 33, further characterized in that:

0.003 <Nb + Zr <0.5%

35. Use of an alloy according to either of claims 33 or 34, for the manufacture of hyper-textured substrates for epitaxy.

36. Hyper-textured substrate for epitaxy comprising an alloy according to either of claims 33 or 34.