Method for manufacturing a nuclear reactor component and nuclear reactor component thus obtained

Abstract

Manufacturing process for a nuclear reactor component and nuclear reactor component thus obtained. The manufacturing process includes obtaining a nickel-based alloy strip with the following composition, in weight percentages: traces ≤ C ≤ 0.08%; traces ≤ Mn ≤ 0.35%; traces ≤ Si ≤ 0.35%; traces ≤ P ≤ 0.015%; traces ≤ S ≤ 0.015%; 17.0% ≤ Cr ≤ 21.0%; traces ≤ Co ≤ 1.0%; 2.80% ≤ Mo ≤ 3.30%; 4.75% ≤ Nb + Ta ≤ 5.50%; 0.65% ≤ Ti ≤ 1.15%; 0.20% ≤ Al ≤ 0.80%; traces ≤ Cu ≤ 0.30%; 50.0% ≤ Ni ≤ 55.0%; traces ≤ B ≤ 0.006%; the remainder being Fe and impurities resulting from the processing, desensitization annealing is carried out in a static furnace at an annealing temperature of 900°C or higher and / or 1050°C or lower for an annealing time of 1 min or higher and / or 180 min or lower. Figure for the abbreviation: Figure 1

Description

Title of the invention: Method for manufacturing a nuclear reactor component and nuclear reactor component thus obtained

[0001] The present invention relates to the field of nickel superalloys, and more specifically to the nickel-based alloy known as INCONEL® 718 (or NC19FeNb) corresponding to the UNS N07718 standard, which is used, for example, to manufacture components of light water reactors (or LWRs), for example structural components or components of nuclear fuel assemblies intended to be inserted into these light water reactors.

[0002] The classic chemical composition of the INCONEL®718 alloy (hereafter referred to as "alloy 718") is as follows: - traces < C < 0.08%; - traces < Mn < 0.35%; - traces < Si < 0.35%; - traces < P < 0.015%; - traces < S < 0.015%; 17.0% < Cr < 21.0%; - traces < Co < 1.0%; 2.80 < Mo < 3.30%; 4.75% < Nb + Ta < 5.50%; 0.65% < Ti < 1.15%; 0.20% < Al < 0.80%; - traces < Cu < 0.30%; 50.0% < Ni < 55.0%; - traces < B < 0.006%;

[0003] the remainder being Fe and impurities resulting from the processing.

[0004] Nuclear reactor components, particularly those of nuclear fuel assemblies, are often limited in size and thickness. Many of these components are manufactured by forming one or more metal sheets.

[0005] Such components require particularly high dimensional accuracy.

[0006] Moreover, the environment of a light water nuclear reactor is very specific and imposes very particular stresses on alloy 718, linked in particular to radioactivity.

[0007] Components of light water nuclear reactors are particularly exposed to the risk of environmentally assisted cracking, and in particular to the risk of stress corrosion cracking.

[0008] US5244515 and US5047093 propose a high-temperature heat treatment or "annealing" temperature to slow down the propagation of stress corrosion cracks in a 718 alloy used in a nuclear application, to reduce the appearance of the γ phase in the microstructure in the 718 alloy.

[0009] US8470106 discloses a crack-assisted desensitization anneal by the environment, the desensitization annealing being carried out under a hydrogen atmosphere and aiming to eliminate as many interstitial elements as possible in the 718 alloy.

[0010] One of the aims of the invention is to make it possible to obtain an alloy whose resistance to environmentally assisted cracking, particularly under conditions likely to cause stress corrosion cracking, is improved, while preserving the mechanical properties, particularly in the aged state.

[0011] To this end, the invention proposes a method for manufacturing a component of a nuclear reactor, in particular a light water nuclear reactor, the manufacturing method comprising the steps of: - obtaining a strip made of nickel-based alloy with the following chemical composition, expressed in weight percentages: traces < C < 0.08%; traces < Mn < 0.35%; traces < Si < 0.35%; traces < P < 0.015%; traces < S < 0.015%; 17.0% < Cr < 21.0%; traces < Co < 1.0%; 2.80 < Mo < 3.30%; 4.75% < Nb + Ta < 5.50%; 0.65% < Ti < 1.15%; 0.20% < Al < 0.80%; traces < Cu < 0.30%; 50.0% < Ni < 55.0%; traces < B < 0.006%; the remainder being Fe and impurities resulting from the processing; - carrying out a desensitizing annealing of the strip in a static oven to obtain an annealed strip, comprising maintaining the strip at an annealing temperature equal to or greater than 900°C, in particular equal to or greater than 920°C, preferably equal to or greater than 940°C and / or equal to or less than 1050°C, in particular equal to or less than 1000°C, preferably equal to or less than 980°C, for an annealing time equal to or greater than 1 min, in particular equal to or greater than 15 min, preferably equal to or greater than 30 min and / or equal to or less than 180 min; and - shaping the annealed strip to obtain the component.

[0012] Performing an annealing of the alloy 718 in the form of a metal strip and before shaping the strip, at a limited temperature and with an appropriate duration, makes it possible to increase the β phase content of the microstructure of the alloy 718.

[0013] It has been found that such an increase in the γ phase content makes it possible to reduce sensitivity to environmentally assisted cracking.

[0014] Increasing the β-phase content does not significantly degrade the room-temperature ductility of the alloy 718 obtained for easy forming, with a high value, which can go up to 40% or even more, for elongation at break.

[0015] This has the advantage of keeping the hot and cold forming tools under low stress and / or thus allowing for better dimensional accuracy of the strip. This good dimensional accuracy is important to achieve, particularly on nuclear fuel assembly components.

[0016] Carrying out the final annealing step of solution setting in a static furnace and on the metal strip, preferably conditioned in a coil, makes it possible to promote the appearance of the β phase in a controlled manner, with an economical implementation.

[0017] The strip is processed as a whole before the strip is shaped to form a component, and preferably several components.

[0018] Carrying out the annealing step on the strip, i.e. after the transformation steps necessary to obtain the strip, such as hot forging, hot rolling and / or cold rolling, makes it possible to decouple the obtaining of the strip and the annealing.

[0019] The strip is for example manufactured and preferably wound at a first manufacturing location, then transported to a second manufacturing location distant from the first manufacturing location, for example by road transport, rail transport, sea transport and / or air transport, then heat-treated and shaped at the second manufacturing location to obtain one and preferably several components from the strip.

[0020] The annealing carried out on the metal strip before shaping it to obtain the component, makes it possible to obtain a particular microstructure which is neither totally recrystallized nor restored, and which includes a non-negligible fraction of the β phase.

[0021] However, it allows the final product to retain mechanical properties comparable to those of conventionally treated alloys 718 used by the nuclear industry, which until now were thought not to contain any β phase at all, as indicated for example in the article "The Roles of Thermal Mechanical Treatment and β Phase in the Stress Corrosion Cracking of Alloy 718 in Primary Water" by M. Wang et al., Corrosion Science 160 (2019) 108168.

[0022] In particular examples, the manufacturing process includes one or more of the following optional features, taken individually or in all technically possible combinations:

[0023] - during the desensitization annealing step, the strip is heated from the ambient temperature until the annealing temperature and then maintained at the annealing temperature for the duration of the annealing;

[0024] - the manufacturing process comprises, after the desensitization annealing step, an active cooling step of the annealed strip implemented before the forming step, preferably at least while the temperature of the strip is equal to or greater than a cooling temperature, for example equal to 600°C;

[0025] - the desensitization annealing step is carried out under vacuum or under an atmosphere protective, for example a non-oxidizing atmosphere, in particular a non-oxidizing atmosphere made up of argon and / or hydrogen;

[0026] - the desensitization annealing step is implemented on the conditioned strip in the form of a reel;

[0027] - the strip has a thickness equal to or less than 0.70 mm, in particular a thickness equal to or less than 0.60 mm, preferably a thickness equal to or less than 0.30 mm;

[0028] - at the end of the desensitization annealing step, the β phase content of the microstructure of the nickel base alloy is equal to or greater than 0.1%, in particular equal to or greater than 1%, preferably equal to or greater than 3% and / or equal to or less than 17%, in particular equal to or less than 12%, preferably equal to or less than 8%;

[0029] - the shaping step includes one or more sub-steps of planing, cutting, stamping, bending and / or machining

[0030] - the step of obtaining the strip comprises one or more of the following steps: obtaining an ingot made from the nickel-based alloy; carrying out a homogenization anneal of the ingot; hot processing of the ingot to obtain a hot-processed product; cold processing of the hot-processed product to obtain the strip, the cold processing being carried out in a cold processing step or a series of cold processing sub-steps with an intermediate annealing sub-step between each cold processing sub-step and the next; and / or an intermediate annealing step between the hot processing step and the cold processing step;

[0031] - the manufacturing process is carried out without annealing between the transformation step and cold and the desensitization annealing step.

[0032] - the manufacturing process includes an aging annealing step implemented after the desensitization annealing step, preferably carried out at a temperature equal to or greater than 500°C and / or equal to or less than 800°C and / or for a duration equal to or greater than 1 h and / or equal to or less than 100 h;

[0033] - the aging annealing step is carried out after the shaping and / or during the formatting stage;

[0034] - the manufacturing process is carried out without annealing the nickel-based alloy between the step desensitization annealing and aging annealing stage;

[0035] - the manufacturing process is carried out without annealing of the nickel-based alloy after the desensitization annealing step;

[0036] - the component is a nuclear fuel assembly element, in particular an element of a spacer grid of a nuclear fuel assembly, an element of a mixing grid of a nuclear fuel assembly or spring of a nuclear fuel assembly.

[0037] The invention also relates to a nickel-based alloy component of a nuclear reactor, in particular a light water reactor, produced according to a manufacturing process as defined above.

[0038] In exemplary embodiments, at the end of the desensitizing annealing step, the β-phase content of the microstructure of the nickel-based alloy is equal to or greater than 0.1%, in particular equal to or greater than 1%, preferably equal to or greater than 3% and / or equal to or less than 17%, in particular equal to or less than 12%, preferably equal to or less than 8%.

[0039] The invention and its advantages will become apparent from the following description, given solely by way of non-limiting example, and made with reference to the accompanying drawings, [Fig.1] which illustrate steps in a manufacturing process for a nuclear reactor component.

[0040] As illustrated in [Fig.1], the manufacturing process aims to obtain a component C of a nuclear reactor, in particular a light water nuclear reactor, the component being made of alloy 718 and having a particular microstructure.

[0041] The manufacturing process comprises:

[0042] - a step El of obtaining a strip B made of alloy 718 of composition The following chemical composition, expressed as weight percentages: traces < C < 0.08%; traces < Mn < 0.35%; traces < Si < 0.35%; traces < P < 0.015%; traces < S < 0.015%; 17.0% < Cr < 21.0%; traces < Co < 1.0%; 2.80 < Mo < 3.30%; 4.75% < Nb + Ta < 5.50%; 0.65% < Ti < 1.15%; 0.20% < Al < 0.80%; traces < Cu < 0.30%; 50.0% < Ni < 55.0%; traces < B < 0.006%; the remainder being Fe and impurities resulting from the processing; - a step E2 of annealing strip B in a static furnace FS to obtain a heat-treated strip B, and - a step E3 of shaping the annealed strip B to obtain component C.

[0043] Step E1 of obtaining band B includes, for example, one or more of the following steps: - an Eli step of obtaining an L ingot of alloy 718; - a step E12 of carrying out a homogenization anneal of the ingot L; - a hot transformation step E13 of the ingot L to obtain a hot-transformed product P; - a hot-processing annealing step E14 applied to the hot-processed product P; - a cold processing step E15 of the hot-processed product P, which may be annealed after hot processing to obtain strip B, the cold processing step being carried out in a single cold processing substep E151 or a series of cold processing substeps E151, with an intermediate annealing substep E152 between each cold processing substep E151 and the next; and / or - a winding step E16 to condition the B tape into a reel.

[0044] Preferably, the step El of obtaining the strip B includes the step Eli of obtaining an ingot, the step E12 of carrying out a homogenization anneal of the ingot L, the step E13 of hot processing of the ingot L to obtain a hot-processed product P, the step E14 of annealing after hot processing and the step E15 of cold processing of the hot-processed product P.

[0045] In possible variants, the homogenization annealing step E12 is omitted, the hot processing step E13 is omitted, the hot processing annealing step E14 and / or the cold processing step E15 is omitted.

[0046] Step El 1 of obtaining an ingot L includes, for example, in a conventional manner, the preparation in the liquid state and the casting, in the form of an ingot L, of an alloy 718 of composition as previously mentioned.

[0047] Typically, this elaboration is carried out by a process or a series of processes which give the alloy 718 good purity in terms of chemical composition and inclusion cleanliness.

[0048] The preparation of alloy 718 in the liquid state in a vacuum induction furnace (VIM), followed by the casting of an ingot which then undergoes remelting under electroconductive slag to improve its purity and inclusion cleanliness, is a non-limiting example of such a sequence of processes.

[0049] Where appropriate, the optional homogenization annealing step E12 of the ingot L is carried out for example at a homogenization temperature between 1,000°C and 1,400°C and / or for a homogenization time between 30 min and 24 h.

[0050] The E12 homogenization annealing step of the ingot L is carried out in a static furnace.

[0051] Where appropriate, the hot processing step E13 is carried out in a temperature range between 750°C and 1200°C, for example by hot rolling and / or hot forging.

[0052] Preferably, the hot processing step E13 is carried out with a forging ratio (the ratio between the section after hot processing and the section before hot processing) of at least 0.5.

[0053] The hot processing step E13 is preferably implemented so as to obtain a hot processed product P having the form of a strip or a plate.

[0054] When a hot-processing annealing step 14 is implemented, it is carried out for example at a hot-processing annealing temperature of between 750°C and 1200°C and / or for a hot-processing annealing time of between 1 min and 5 h.

[0055] Such a hot-processing annealing step E14, carried out after a hot-processing step, makes it possible to ensure the obtaining of a homogeneous and reproducible microstructure regardless of the precise conditions of implementation of the hot-processing step E13.

[0056] The E14 annealing step after hot processing is carried out for example in a conveyor furnace or a static furnace.

[0057] The cold processing step E15 is implemented on the hot-processed product P during the hot processing step E13 and optionally annealed during the hot processing annealing step E14, to obtain the strip B.

[0058] The cold forming step E15 is carried out by any type of cold forming. The cold forming step E15 includes, for example, at least one sub-step E151 of cold rolling.

[0059] The cold processing step E15 comprises, for example, a single cold rolling substep E151 or a series of cold rolling substeps E151 with an intermediate annealing substep E152 between each cold rolling step E151 and the next.

[0060] Each sub-step E151 of cold rolling is carried out in one or more rolling passes. Each rolling pass corresponds to the passage of the product between two rollers of a rolling mill between which the thickness of the product P is reduced.

[0061] Each rolling pass has, for example, a reduction rate of at least 10%. The reduction rate is the difference between the cross-sectional area before rolling and the cross-sectional area after rolling, expressed as a percentage.

[0062] Where appropriate, each intermediate annealing substep 152 includes heating the product P to a temperature equal to or greater than 940°C for a duration equal to or greater than 10 seconds.

[0063] Each intermediate annealing substep 152 restores ductility to the alloy 718 before the next cold processing substep E151.

[0064] Each sub-step El52 of intermediate annealing is carried out for example in a continuous furnace.

[0065] The cold processing step E15 is for example only carried out by cold rolling in a cold rolling substep E151 or a series of cold rolling substeps E151 alternating with intermediate annealing substeps E152.

[0066] Where appropriate, winding step E16 is carried out in a winding device, for example located downstream of a rolling mill used during cold processing step E15, to recover the strip B at the exit of this rolling mill and wind it into a coil.

[0067] The strip B obtained at the end of the obtaining step El preferably has a thickness equal to or less than 0.70 mm, in particular a thickness equal to or less than 0.60 mm, preferably a thickness equal to or less than 0.30 mm.

[0068] The desensitization annealing step E2 is carried out on the B strip, preferably conditioned in a reel, in a static FS oven, to obtain an annealed B strip.

[0069] During the desensitizing annealing step E2, the strip B is heated to an annealing temperature of 900 °C or higher, in particular 920 °C or higher, preferably 940 °C or higher and / or 1050 °C or lower, in particular 1000 °C or lower, preferably 980 °C or lower, and maintained at the annealing temperature for an annealing time of 1 min or higher, in particular 15 min or higher, preferably 30 min or higher and / or 180 min or lower.

[0070] The desensitization annealing step E2 is preferably carried out in the static FS furnace under controlled atmosphere or under vacuum.

[0071] The controlled atmosphere is, preferably, a non-oxidizing atmosphere, formed for example of a neutral gas or a mixture of neutral gases such as argon (Ar), nitrogen (N2) and their mixtures, or a reducing atmosphere such as hydrogen (H2) or an Ar / H2 mixture.

[0072] Vacuum desensitization annealing is for example carried out at a pressure below 102 mbar.

[0073] In one variant, the desensitization annealing step E2 is carried out under an oxidizing atmosphere, provided that the desensitization annealing is followed by a pickling and / or descaling operation aimed at removing an oxidized layer that has formed on the surface of the strip during the desensitization annealing.

[0074] At the end of the desensitizing annealing step E2, the γ phase content of the microstructure of alloy 718 is equal to or greater than 0.1%, in particular equal to or greater than 1%, preferably equal to or greater than 3% and / or equal to or less than 17%, in particular equal to or less than 12%, preferably equal to or less than 8%.

[0075] Optionally, the manufacturing process includes an active cooling step E21 implemented after the desensitizing annealing step E2.

[0076] Active cooling means that the annealed strip B is cooled more rapidly than if it were simply left in open air, for example by forcing a heat exchanger. Active cooling of the strip B is implemented, for example, by injecting cold inert gas into the furnace chamber.

[0077] The active cooling step E21 prevents the hardening phases from precipitating in the microstructure of alloy 718.

[0078] The active cooling step E21 is for example implemented between the desensitization annealing temperature and a cooling temperature strictly lower than the desensitization annealing temperature, and for example equal to 600°C.

[0079] Below the cooling temperature, cooling may be slower. It may, for example, be carried out in ambient air.

[0080] Preferably, the active cooling step E21 is carried out under a non-oxidizing protective atmosphere, for example consisting of Ar, H2 with a dew point of -51°C or lower, or an Ar / H2 mixture.

[0081] The non-oxidizing protective atmosphere is for example removed as soon as the temperature of the strip reaches a temperature for air release, for example equal to about 150°C.

[0082] The active cooling step E21 is preferably implemented on the B strip conditioned in a reel.

[0083] After the desensitizing annealing step E2 possibly followed by the active cooling step E21, the alloy 718 of the B band is suitable for forming, in particular cold forming.

[0084] The desensitizing annealing step E2 is preferably the last annealing undergone by the alloy 718 during the manufacture of the component.

[0085] The shaping step E3 includes, for example, cutting the strip B, stamping the strip B, bending the strip B and / or machining the strip B to form the component C. The shaping step E3 is optionally preceded by a flattening step of the strip B.

[0086] Component C is, for example, a spring R of a grid of a nuclear fuel assembly, or, for example, a plate of a grid of an assembly of nuclear fuel formed of a plurality of interlocking plates delimiting cells, each cell being intended to receive a nuclear fuel rod, each plate comprising bosses D (rigid), springs R (elastic) formed in the plate and / or attached to the plate to transversely support the nuclear fuel rods and / or fins A, arranged for example on an upper edge and / or a lower edge of the plate to force a mixture of a cooling fluid through the nuclear fuel assembly during the operation of the nuclear reactor.

[0087] The component C is obtained for example by flattening the strip B initially wound in a coil to obtain a flat strip B, then shaping the strip B, for example by cutting in the strip B and shaping by cutting, stamping and / or machining to form one or more springs R and / or plates comprising bosses D and / or springs R and / or fins A formed in the plate.

[0088] The manufacturing process optionally includes an aging annealing step E4 implemented after the desensitizing annealing step E2.

[0089] The aging annealing step E4 is implemented before the forming step E3, after the forming step E3 and / or during the forming step E3, for example between sub-steps of the forming step E3.

[0090] The aging annealing step E4 is carried out in one or more steps during which the base alloy 718 is maintained at an aging temperature between 500°C and 800°C and / or for an aging time between 1 h and 100 h.

[0091] The implementation of an E4 aging annealing step makes it possible to increase the hardness without changing the quantity of phase ô obtained after the desensitization treatment.

[0092] Tests were carried out on metal strips made from an alloy 718 of composition, expressed in weight percentages: Cr = 19.0%; Mo = 3.0%; Nb + Ta = 5.15%, Ti = 0.90%; Al = 0.50%; Ni = 52%; the remainder being Fe and impurities resulting from the processing.

[0093] Each strip was obtained by implementing a step El 1 of obtaining an ingot L of alloy 718, a step E12 of carrying out a homogenization anneal of the ingot L, a step El3 of hot processing of the ingot L to obtain a hot-processed product P, a step E14 of annealing after hot processing applied to the hot-processed product P, a step El5 of cold processing of the hot-processed product P and annealing after hot processing to obtain the strip B, the cold processing step being carried out in a single substep E151 of cold processing or a series of substeps of cold processing E151, with an intermediate annealing substep E152 between each cold processing substep E151.

[0094] The strips then underwent different desensitization annealings (desensitization step E2), a shaping step E3 to form nuclear fuel assembly grid springs R and an aging annealing (aging step E4).

[0095] Measurements were taken before and after aging annealing to determine the Vickers hardness (Hv) of alloy 718 in the R springs, as well as the volume fraction of phase β.

[0096] In the comparative example (not in accordance with the invention), the strip underwent annealing at a high temperature of 1060°C, which is higher than the solvus of the γ phase. In Examples 1 to 3 (in accordance with the invention), the strips underwent desensitization annealing at temperatures of 920°C, 940°C and 970°C respectively, which are lower than the solvus of the γ phase.

[0097] The results are presented in the table below.

[0098] [Tables 1] Annealing Before aging After aging Temperature Duration Vickers Hardness Hv Phase α Vol. fraction Vickers Hardness Hv Phase α Vol. fraction Example without desensitization 1060°C 1 min 190 0% 470 0% Example 1 with desensitization 920°C 1 hour 340 6-8% 470 6-8% Example 2 with desensitization 940°C 1 hour 320 6-8% 460 6-8% Example 3 with desensitization 970°C 30 min 300 6-8% 470 6-8%

[0099] The results show greater hardness when the strip has undergone a desensitizing annealing step at a temperature between 920°C and 970°C, while retaining a significant fraction of the β phase, here between 6 and 8% in Examples 1 to 3, whereas the β phase content is very low, and in particular practically zero, in the absence of desensitization as recommended, as illustrated by the Comparative Example.

[0100] The aging step allows for increased hardness without altering the quantity of β phase obtained after the desensitization treatment.

[0101] Thus, the desensitization annealing step, particularly in combination with the aging annealing step, makes it possible to obtain a product sufficiently supplied with the β phase, while exhibiting sufficient hardness to fulfill its functions

[0102] Carrying out desensitization annealing at a relatively low desensitization annealing temperature and for a desensitization annealing time that allows a fraction of the β phase to remain in the alloy 718, possibly subjected to partial work hardening due to the shaping carried out after desensitization annealing, is, surprisingly, effective in improving protection against crack initiation.

[0103] The proposed manufacturing process makes it possible to maintain a level of mechanical properties in the aged state similar to that obtained with high-temperature annealing, carried out at a temperature above 1050°C, i.e. above the solvus of the γ phase.

[0104] It goes without saying that in addition to the operations described which aim to obtain the characteristics and properties of alloy 718 aimed in particular at improving its resistance to the initiation and propagation of cracks, additional operations which are usual can be carried out, such as dropping parts of the initial ingot whose properties would not be satisfactory in any case, pickling, straightening of the semi-finished products or of the final product, etc.

[0105] The essential point is that these operations do not lead to modifications of the microstructure of alloy 718 which would be contrary to obtaining the properties targeted by the invention on the final products.

Claims

Demands

1. A method for manufacturing a component of a nuclear reactor, in particular a light water nuclear reactor, the manufacturing process comprising the steps of: - obtaining a strip made of nickel-based alloy with the chemical composition, expressed in weight percentages: traces < C < 0.08%; traces < Mn < 0.35%; traces < Si < 0.35%; traces < P < 0.015%; traces < S < 0.015%; 17.0% < Cr < 21.0%; traces < Co < 1.0%; 2.80% < Mo < 3.30%; 4.75% < Nb + Ta < 5.50%; 0.65% < Ti < 1.15%; 0.20% < Al < 0.80%; traces < Cu < 0.30%; 50.0% < Ni < 55.0%; traces < B < 0.006%; the remainder being Fe and impurities resulting from the processing;- carrying out a desensitizing annealing of the strip in a static oven to obtain an annealed strip, comprising maintaining the strip at an annealing temperature equal to or greater than 900°C, in particular equal to or greater than 920°C, preferably equal to or greater than 940°C and / or equal to or less than 1050°C, in particular equal to or less than 1000°C, preferably equal to or less than 980°C, for an annealing time equal to or greater than 1 min, in particular equal to or greater than 15 min, preferably equal to or greater than 30 min and / or equal to or less than 180 min; and - shaping the annealed strip to obtain the component, in which the desensitizing annealing step is carried out on the strip conditioned in the form of a reel.

2. A method according to claim 1, wherein, during the desensitizing annealing step, the strip is heated from room temperature to the annealing temperature and then maintained at the annealing temperature for the duration of the annealing.

3. A method according to claim 1 or 2, comprising, after the desensitizing annealing step, an active cooling step of the annealed strip implemented before the forming step, preferably at least while the strip temperature is equal to or above a cooling temperature, for example equal to 600°C.

4. A process according to any one of the preceding claims, wherein the desensitizing annealing step is carried out under vacuum or under a protective atmosphere, for example a non-oxidizing atmosphere, in particular a non-oxidizing atmosphere made up of argon and / or hydrogen.

5. A method according to any one of the preceding claims, wherein the strip has a thickness equal to or less than 0.70 mm, in particular a thickness equal to or less than 0.60 mm, preferably a thickness equal to or less than 0.30 mm.

6. A process according to any one of the preceding claims, wherein, at the end of the desensitizing annealing step, the β-phase content of the microstructure of the nickel-based alloy is equal to or greater than 0.1%, in particular equal to or greater than 1%, preferably equal to or greater than 3% and / or equal to or less than 17%, in particular equal to or less than 12%, preferably equal to or less than 8%.

7. A method according to any one of the preceding claims, wherein the shaping step comprises one or more substeps of planing, cutting, stamping, bending and / or machining.

8. A process according to any one of the preceding claims, wherein the strip-making step comprises one or more of the following steps: - obtaining an ingot made from the nickel-based alloy; - carrying out a homogenizing anneal of the ingot; - hot processing of the ingot to obtain a hot-processed product; - cold processing of the hot-processed product to obtain the strip, the cold processing being carried out in a cold processing step or a series of cold processing substeps with an intermediate annealing substep between each cold processing substep and the next; and / or - an intermediate annealing step between the hot processing step and the cold processing step.

9. Process according to claim 8, carried out without annealing between the cold processing step and the desensitizing annealing step.

10. A process according to any one of the preceding claims, comprising an aging annealing step carried out after the desensitizing annealing step, preferably carried out at a temperature of 500°C or higher and / or 800°C or lower and / or for a duration of 1 h or higher and / or 100 h or lower.

11. A method according to claim 10, wherein the aging annealing step is carried out after the forming step and / or during the forming step.

12. A process according to claim 10 or claim 11, without annealing the nickel-based alloy between the desensitizing annealing step and the aging annealing step.

13. A process according to any one of the preceding claims, without annealing the nickel-based alloy after the desensitizing annealing step.

14. A method according to any one of the preceding claims, wherein the component is a nuclear fuel assembly element, in particular an element of a spacer grid of a nuclear fuel assembly, an element of a grid of mixture of a nuclear fuel assembly or spring of a nuclear fuel assembly.

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