Method for preventing abnormal grain growth in beta processed titanium alloys

Abstract

The present invention relates to a method for manufacturing a β-treated titanium alloy part without abnormally growing beta grains, characterized in that it comprises the following successive steps: a) first heat treatment of a titanium alloy blank at a core blank temperature higher than the β transus temperature of the titanium alloy so as to obtain a β-treated blank; b) final deformation step of the β-treated blank, this final deformation step being carried out at a core blank temperature lower than the β transus temperature of the titanium alloy with a local plastic strain level ≥ 0.1 and with a plane strain level ≤1 so as to obtain a titanium alloy part;c)- second heat treatment of the titanium alloy part at a core temperature higher than the transus temperature β of the titanium alloy so as to obtain a β-treated titanium alloy part.;

Description

Domain Technical

[0001] The present invention relates to the field of beta-treated titanium alloys, particularly those intended for aeronautical applications. Previous technique

[0002] When manufacturing titanium alloy parts, it may be necessary to subject them to a final heat treatment at a temperature above the beta transus temperature in order to improve the damage tolerance and fracture resistance of the part and thus obtain a microstructure suitable for applications in the field of aeronautics.

[0003] However, it has been discovered that beta treatment, i.e., heat treatment at a temperature above the beta transus temperature, can cause abnormal growth of beta grains, potentially impacting the mechanical properties of the part. This phenomenon is called abnormal grain growth (AGG) and is observed primarily in parts that have undergone plastic deformation during manufacturing, such as forging. It is described in particular in the article by Byres et al. ("Analysis of the development of abnormal grain structures during beta annealing of Ti-64 wrought product," MATEC Web conferences, 321, 12043 (2020)).The literature has demonstrated that this phenomenon is linked to the development of a very pronounced crystallographic texture in the beta phase of the alloy. This can develop during forging operations performed at temperatures below the beta transus temperature due to the significant cumulative reduction in cross-section from the ingot to the forged blank and from the forged blank to the finished part, creating a substantial amount of localized plastic deformation within the volume of the forged part. In particular, it has been shown that a cube or cube-turned crystallographic texture—developed during a rough forging phase—can induce excessive grain growth during the final beta treatment, even if a finishing die-forging phase occurs between the rough forging and the final beta treatment.It has been shown that the presence of a few randomly oriented grains within a zone of strong cube or cube-turned crystallographic texture is a favorable condition for the abnormal growth of these randomly oriented grains, to the detriment of grains exhibiting the cube or cube-turned texture. Forged parts with microstructures composed of abnormally large grains may exhibit degraded mechanical and durability properties, with the initiation and eventual propagation of fatigue cracks being the most affected. (An investigation of the Development of coarse grains during beta annealing of hot-forged Ti-6Al-4V, NC Levkulich, S / L. Semiatin, EJ Payton, S. Srivatsa and AL Pilchak, Met. And Mat. Trans. A, 52A (2021) 1353).

[0004] US patent applications 2017 / 0175241 and 2019 / 0032184 propose a method to prevent abnormal grain growth using a very specific final thermal cycle in which the beta treatment step is directly preceded by a recrystallization step at very specific temperatures. The abnormal grain growth phenomenon described in this patent is said to be linked to a localization of significant deformation within forged titanium alloy blanks. It makes no mention of the grain growth phenomenon caused by the appearance of a zone with a strong turned cube texture. The application of a recrystallization treatment below the beta transus temperature is recommended in this patent. However, this type of heat treatment has not been shown to eliminate the cube or turned cube texture before the final heat treatment, and therefore has not been shown to prevent the AGG phenomenon described in this patent application.

[0005] It has also been proposed to solve this problem by avoiding critical deformation paths, such as plane deformation (article by Pilchak et al. MATEC Web conferences, 321, 12007 (2020)). This type of solution is very complex and costly to manage industrially when several forging operations must be chained together to obtain a complex shape.

[0006] Application WO2016 / 040996 describes a process applicable exclusively to beta-metastable alloys, based on an aging step to create precipitates for microstructure control. The described aging step comprises a temperature increase at a rate of 10°C per minute or less, with the aging temperature being 90-110°C below the beta transus temperature, i.e., between Tβ - 110°C and Tβ - 90°C. This heating rate is necessary, according to the application, to produce a microstructure exhibiting uniform alpha phase dispersion. The subsequent deformation must be carried out at a temperature below or equal to the aging temperature. This application specifically concerns beta-metastable alloys; the claimed deformation temperature range is poorly suited to alpha / beta alloys such as Ti6Al4V.Furthermore, the heating rate constraint during aging to obtain fine and homogeneous precipitation is typical of metastable beta alloys. Finally, this request does not address the case where abnormal grain growth is a consequence of the presence of a particularly pronounced crystallographic texture in the beta phase.

[0007] The inventors discovered that in certain cases it was possible to avoid the presence of abnormally large beta grains in the final part by applying a first heat treatment at a temperature higher than the beta transus temperature (first beta treatment) before the final deformation step, followed by a second heat treatment at a temperature higher than the usual beta transus temperature (second beta treatment), without requiring an aging step, let alone a survivalist step. Indeed, the first beta treatment allows the abnormal growth of beta grains to develop on the blank if it has developed a very pronounced cube or rotated cube crystallographic texture during the roughing stages. It should be noted that the abnormally growing grains have a random orientation, and their development eliminates the cube or rotated cube crystallographic texture from which they originate.The final deformation step then recrystallizes the grains to obtain a homogeneous structure in the resulting part, the 2nd beta treatment of this part thus not causing any new abnormal grain growth, the resulting part thus showing no abnormally growing beta grains.

[0008] This solution is much simpler than the prior art method, and the implementation cost is moderate. Furthermore, it avoids restricting the deformation path of the forged blank before the first heat treatment, thus allowing greater flexibility in the part manufacturing process. This is a significant advantage when manufacturing parts with complex geometries that require a series of forming steps.

[0009] US document 5,277,718 describes complex manufacturing processes for titanium alloy billets from ingots that include, between thermomechanical treatment steps in the alpha beta range, annealing and forging steps above the beta transus.

[0010] Another objective of the present invention is therefore to provide a more rational, economical, and reliable manufacturing process that overcomes the drawbacks of the prior art. The inventors have discovered, surprisingly, that it is possible to obtain an excellent final microstructure by applying minimal deformation in the alpha / beta range between the two beta treatments. For example, deformation in the beta range would require imposing significant plastic deformation at every point of the blank to ensure a fine and homogeneous final microstructure, which is difficult to guarantee for complex shapes. This simplification of the process not only reduces costs and cycle times but also improves the control and reproducibility of the final microstructure. Description of the invention

[0011] The present invention therefore relates to a method for manufacturing a part made of β-treated titanium alloy without abnormally growing beta grains, characterized in that it comprises the following successive steps: a) - first heat treatment of a titanium alloy blank at a core temperature of the blank (or core temperature of the blank) higher than the transus temperature β of the titanium alloy so as to obtain a β-treated blank; b) - final deformation step of the β-treated blank, this final deformation step being carried out at a core temperature of the blank lower than the transus temperature β of the titanium alloy with a local plastic strain level ≥ 0.1, in particular in areas likely to have anomalous grain growth, advantageously throughout the blank, and with a plane strain level ≤1 so as to obtain a titanium alloy part; c)- second heat treatment of the titanium alloy part at a core temperature (or core temperature of the part) higher than the transus temperature β of the titanium alloy so as to obtain a β treated titanium alloy part.

[0012] In this application, the expressions "between ... and ...", "from ... to ..." and "within the range ...-...", should be understood to include the limits unless explicitly stated otherwise.

[0013] For the purposes of this invention, a "blank" is defined as a semi-finished product obtained after one or more forging operations (forging, rolling, drawing) of an ingot. A blank has a forged microstructure, with finer grains and a more homogeneous structure than an ingot, but it may have developed a pronounced crystallographic texture during its shaping.

[0014] For the purposes of this invention, the term "ingot" means the raw metallic product obtained directly after a melting and solidification operation, such as a vacuum remelted ingot (VAR). An ingot typically exhibits a casting macrostructure, with coarse grains and chemical segregation.

[0015] For the purposes of this invention, a "beta-treated" part / work blank is defined as a part / work blank that has undergone heat treatment at a core temperature higher than the beta transus temperature of the constituent alloy of the part / work blank, such that the microstructure of the alloy in the part / work blank is transformed from a mixture of alpha and beta phases into a single beta phase at the treatment temperature. Following the beta treatment and after cooling, no nodular alpha phase (more commonly called primary alpha) remains.

[0016] For the purposes of the present invention, "beta treatment" means a heat treatment at a core temperature of the part / blank higher than the beta transus temperature of the alloy constituting the part / blank so as to transform the microstructure of the alloy of the part / blank from a mixture of alpha and beta phases into a single beta phase at the treatment temperature.

[0017] The "beta transus temperature" according to the present invention is the lowest temperature at which the titanium alloy according to the invention contains 100% beta phase (complete dissolution of the alpha phase). The beta transus temperature of the titanium alloy can vary from 700°C to 1050°C, depending on the alloy composition. The beta transus temperature of the Ti-6Al-4V alloy is generally between 980°C and 1020°C.

[0018] For the purposes of this invention, "titanium alloy" means any titanium-based alloy, i.e., one containing titanium as the main chemical element (more than 50% by mass) and also containing other chemical elements.

[0019] In an advantageous embodiment, the titanium alloy according to the invention is a titanium alloy containing aluminum, advantageously a titanium alloy containing aluminum and vanadium, more advantageously the Ti-6Al-4V alloy. Particularly advantageously, the titanium alloy according to the invention is a metastable alpha-beta or beta two-phase alloy. Indeed, this type of alloy generally includes combinations of alpha and beta stabilizing chemical elements, such as aluminum or vanadium. Thus, titanium alloys according to the invention can be the alloys Ti-6Al-4V, Ti-6Al-4V-ELI, Ti-6Al-6V-2Sn, Ti-8Mn, Ti-7Al-4Mo, Ti-6Al-2Sn-4Zr-6Mo, Ti-5Al-2Sn-2Zr-4Mo-4Cr otherwise called Ti17, Ti-6Al-2Sn-2Zr-2Mo-2Cr, Ti-3Al-2.5V or Ti-4Al-4Mo-2Sn-0.5Si, Ti-6Al-2Sn-4Zr-2Mo otherwise called Ti6242.In particular, the titanium alloy according to the invention is a two-phase alpha-beta alloy such as Ti-6Al-4V, Ti-6Al-4V-ELI, Ti-6Al-6V-2Sn, Ti-8Mn, Ti-7Al-4Mo, Ti-6Al-2Sn-4Zr-6Mo, Ti-6Al-2Sn-2Zr-2Mo-2Cr, Ti-3Al-2.5V or Ti-4Al-4Mo-2Sn-0.5Si, Ti-6Al-2Sn-4Zr-2Mo otherwise called Ti6242. More particularly it is the Ti-6Al-4V alloy.

[0020] Hillert In 1965, it was demonstrated that the largest grains resulting from normal grain growth are approximately twice the size of average grains. For the purposes of this invention, "abnormally growing beta grain" refers to grains in the beta phase of the alloy whose size is therefore more than twice the grain size of the surrounding matrix.

[0021] For the purposes of this invention, "heat treatment" or "annealing" refers to an operation in which a workpiece or blank is held in a furnace at a target temperature for a predetermined time before being cooled. The purpose of such treatment is to modify the internal microstructure of the alloy (e.g., grain size, phase morphology, phase dissolution or precipitation) and / or to relieve internal stresses in the material. Such static heat treatment is therefore fundamentally different from a thermomechanical processing operation, such as forging, rolling, or extrusion, where temperature and significant plastic deformation are applied simultaneously to change the shape, dimensions, and possibly the microstructure of the workpiece.

[0022] In the context of this application, the terms "heat treatment", "static heat treatment" and "annealing" are used interchangeably to refer to this purely thermal operation, as opposed to a thermomechanical operation such as forging.

[0023] The process according to the present invention therefore comprises a first heat treatment of a titanium alloy blank according to the invention at a core temperature of the blank higher than the beta transus temperature of the titanium alloy, so as to obtain a beta-treated blank (step a)). In the context of this application, this first heat treatment may also be referred to as: "first beta heat treatment". This step a) of the process according to the present invention thus triggers the potential abnormal growth of beta grains in the titanium alloy blank according to the invention.

[0024] In order to perform step a), it is therefore necessary that the entire blank, including its core, be at a temperature higher than the beta transus temperature of the titanium alloy. This is why the temperature indicated for this step is the core temperature of the blank, also called the core temperature of the blank.

[0025] The heat treatment of the titanium alloy in step a) can be carried out with any heat sources, heating devices, and / or heat treatment systems known in the art of titanium forging. For example, vacuum furnaces, electric furnaces, or gas furnaces can be used.

[0026] Depending on the heating technology used for beta treatment, a certain degree of temperature homogeneity is guaranteed within the furnace. To ensure that the temperature at every point of the blank, including in the core of the blank—that is, that the core temperature of the blank is higher than the beta transus during beta treatment—it is therefore necessary to target a core beta treatment temperature of the blank at least equal to the beta transus temperature of the alloy plus a safety margin, which can be a minimum of 14°C, advantageously a minimum of 20°C, and in particular a minimum of 25°C.Advantageously, the core blank temperature during step a) is at least 14°C higher than the transus β temperature of the titanium alloy, advantageously at least 20°C higher than the transus β temperature of the titanium alloy, more advantageously the temperature is greater than or equal to the transus β temperature of the titanium alloy + 25°C.

[0027] It is also preferable not to use an excessively high core blank temperature during step a) for economic reasons, since the aim is to ensure that the core blank temperature during this step is above the beta transus temperature of the titanium alloy. Therefore, it is preferable for the core blank temperature during step a) to be less than or equal to the beta transus temperature of the titanium alloy + 50 °C. Thus, advantageously, in the case of the Ti-6Al-4V alloy, the temperature of step a) is less than or equal to 1055 °C.

[0028] The duration of step a), called the metallurgical holding time (i.e., the holding time at the target temperature in the core of the blank), must be sufficient to allow the entire alloy of the blank to transition from a mixture of alpha and beta phases to a single beta phase. Thus, advantageously, the duration of step a) according to the invention is at least 20 minutes, advantageously at least 30 minutes, in particular at least 45 minutes, and more advantageously, 1 hour.

[0029] For reasons of economy, it is not necessary for the duration of step a) to be excessive. Advantageously, step a) lasts a maximum of 5 hours, more advantageously a maximum of 3 hours, and in particular a maximum of 2 hours.

[0030] The blank produced in step a) of the process according to the present invention can be obtained by any method known to those skilled in the art in the field of titanium alloys, in particular by methods enabling the transformation of an ingot into a blank. Indeed, the deformation path leading to the blank according to the invention is irrelevant. Advantageously, the blank according to the invention is obtained by forging, extrusion, drawing, and / or die forging, more advantageously by forging, particularly at a core temperature of the blank lower than the beta transus temperature of the titanium alloy.Thus advantageously the process according to the invention includes a step a 0 ), prior to step a), of deformation of the titanium alloy blank, in particular by forging, spinning, drawing and / or die forging, more particularly by forging, advantageously at a core blank temperature lower than the transus β temperature of the titanium alloy, in particular to remain in the mixing zone of the alpha and beta phases in order to better control the beta grain size, more particularly in a core blank temperature range between transus beta -10°C and transus beta -80°C.

[0031] In an advantageous embodiment, the treated beta blank obtained in step a) can undergo water quenching before step b) of the process according to the invention. Thus, advantageously, the process according to the present invention comprises an intermediate step a1) between steps a) and b), of water quenching the treated β blank obtained in step a), and step b) is carried out on the treated β blank obtained in step a1). Indeed, the first heat treatment beta in step a) according to the invention can induce surface and subsurface tears in the treated beta blank according to the invention during step b). In this case, rapid cooling, and more specifically water quenching, prevents the precipitation of thick intergranular rims that are brittle, thereby reducing intergranular decohesion, whereas after air quenching, the intergranular decohesion can remain very pronounced.

[0032] Step b) of the process according to the present invention consists of a final deformation step of the treated blank β ​​(obtained in step a) or in step a1)), this final deformation step being carried out at a core blank temperature lower than the transus temperature β of the titanium alloy with a local plastic strain level ≥ 0.1 and with a plane strain level ≤1 so as to obtain a titanium alloy part.

[0033] For the purposes of this invention, the "final deformation step" means a step during which a final plastic deformation is applied to the treated blank obtained in step a) in order to obtain the final part. Indeed, after this step b), there will be no further plastic deformation steps on the resulting part. Obviously, this final part can subsequently undergo one or more finishing treatments such as machining, but such treatments do not introduce any plastic deformation into the part.

[0034] For the purposes of the present invention, "local plastic deformation" means the plastic deformation defined in Reference M600 of Techniques de l'ingénieur published on July 10, 1996 and noted: e which has the following value: ε ¯ = ∫ 0 t ε ¯ ˙ dt Or ε ¯ ˙ is the rate of plastic deformation defined by ε ¯ ˙ = 2 3 ε ˙ : ε ˙ with ε ˙ = λ ∂ φ ∂ σ (plastic flow law) where he / sheis the strain rate tensor, σ the stress tensor, φ(σ)I the von Mises equivalent stress and λ a positive or zero plastic multiplier, which is zero in the plastic domain.

[0035] Advantageously the level of local plastic deformation of step b) is ≥ 0.2.

[0036] For the purposes of the present invention, "plane strain level" means a strain such that the strain rate tensor can be expressed in the following form, by means of a change of reference frame: ε ˙ = 3 2 ε ¯ ˙ 1 0 0 0 0 0 0 0 − 1

[0037] For the purposes of the present invention, the "local plastic strain level" and the "plane strain level" are parameters that can be determined by methods known to those skilled in the art, for example by using process simulation software such as Forge ®< marketed by Transvalor, the above formulas being entered into the Forge ®< software.

[0038] Advantageously, step b) of the process according to the present invention may consist of forging, spinning, drawing and / or die forging, in particular final forging, particularly die forging, more particularly finishing die forging.

[0039] Step b) of the process according to the present invention is carried out at a core blank temperature lower than the transus β temperature of the titanium alloy, in particular to remain in the mixing zone of the alpha and beta phases of the titanium alloy according to the invention, more particularly at a core blank temperature lower than at least 14°C compared to the transus β temperature of the titanium alloy, advantageously lower than at least 20°C compared to the transus β temperature of the titanium alloy, more advantageously at a core blank temperature lower than or equal to the transus beta temperature of the titanium alloy - 25°C.

[0040] The process according to the present invention finally includes a step c) consisting of a second heat treatment of the titanium alloy part at a core temperature higher than the β transus temperature of the titanium alloy so as to obtain a β-treated titanium alloy part. This yields a titanium alloy part comprising only beta grains without abnormal growth, in particular equiaxed beta grains.

[0041] Steps b) and c) of the process according to the present invention allow for the complete recrystallization of the beta grains of the titanium alloy according to the invention, and in particular for the recrystallization of abnormally grown beta grains that may have resulted from the forging phases of the blank. Indeed, step b) allows sufficient energy to be introduced into the titanium alloy so that the beta grains recrystallize during step c).

[0042] Step c) of the process according to the invention is carried out in a conventional manner for a beta treatment. The conditions for carrying out this step, in particular temperature and duration (i.e., metallurgical holding time), are advantageously as described previously in the context of step a). Advantageously, step c) of the process according to the present invention can be carried out under the same conditions, in particular temperature and duration, as the first beta treatment of step a) of the process according to the invention, the only difference being that it is applied to the final part produced in step b) and not to the blank.

[0043] This step c) aims to transform the microstructure of the alloy in the part from a mixture of alpha and beta phases into a single beta phase.

[0044] In order to carry out step c), it is therefore necessary that the whole part, including the core of the part, be at a temperature higher than the beta transus temperature of the titanium alloy.

[0045] In particular, the process according to the invention does not include an ultrasonic inspection step between steps b) and c), more particularly between steps a) and c), of the process according to the invention.

[0046] More particularly, the process according to the invention does not include, between step a) and step b), in particular between step a) and step c), heat treatment or annealing at a core blank temperature lower than the transus β temperature of the titanium alloy.

[0047] In a particular embodiment, the process according to the invention does not include, between steps (a) and (b), more particularly between steps (a) and (c), an aging step by heating the alloy (in particular the blank and / or the part) at a heating rate less than or equal to 10°C per minute up to an aging temperature between T β - 110°C and T β - 90°C (i.e. to a temperature 90-110°C below the beta transus temperature) and holding this alloy at the aging temperature for at least 5 hours.

[0048] In another particular embodiment, the process according to the invention does not include, between steps (a) and (b), more particularly between steps (a) and (c), an aging step by heating the alloy (in particular the blank and / or the part) at a heating rate less than or equal to 10°C per minute up to an aging temperature between T β - 110°C and T β - 90°C (i.e. to a temperature 90-110°C below the beta transus temperature) and maintaining this alloy at the aging temperature.

[0049] In another particular embodiment, the process according to the invention does not include, between steps (a) and (b), more particularly between steps (a) and (c), an aging step by heating the alloy (in particular the blank and / or the part) to an aging temperature between T β - 110°C and T β - 90°C (i.e. to a temperature 90-110°C below the beta transus temperature) and maintaining this alloy at the aging temperature.

[0050] In another particular embodiment, the process according to the invention does not include, between steps (a) and (b), more particularly between steps (a) and (c), an aging step by heating the alloy (in particular the blank and / or the part) at a heating rate less than or equal to 10°C per minute up to an aging temperature and maintaining the alloy at the aging temperature.

[0051] In another particular embodiment, the process according to the invention does not include, between steps (a) and (b), more particularly between steps (a) and (c), an aging step by heating the alloy (in particular the blank and / or the part) to an aging temperature and maintaining this alloy at the aging temperature.

[0052] Advantageously, the titanium alloy part of the process according to the invention is intended for aeronautics, advantageously it is an aeronautical structural part, in particular for an airplane.

[0053] Even more specifically, the piece according to the invention is not a billet.

[0054] The present invention will be better understood upon reading the description of the following examples, which are given by way of non-limiting illustration. EXAMPLE

[0055] A Ti-6Al-4V alloy billet with a transus temperature of 1000°C, measuring 110 mm x 80 mm x 80 mm, underwent hydraulic press forging at 960°C, followed by final die forging at 970°C with a local plastic strain of 0.1 and a plane strain ≤1 (final deformation stage) using a 300T hydraulic press, and then a one-hour heat treatment at 1030°C (final beta treatment) (comparative example 1). Abnormally growing grains were observed in the center of the billet, reaching a size of approximately -7 ASTM according to ASTM E112, 2021. This abnormal grain growth is linked to the presence of a cube-like crystallographic texture, created during the initial forging phase at 960°C.

[0056] Another Ti-6Al-4V alloy billet with a transus of 1000°C, identical in size to that of comparative example 1, underwent the same treatment as described in comparative example 1 under the same conditions (forging at 960°C, final die forging at 970°C, final beta treatment at 1030°C for one hour). The only difference was the implementation of an initial beta treatment at 1030°C for one hour between the forging and final die forging stages (example 1). No abnormally growing grains were observed; the billet's microstructure exhibited equiaxed beta grains with a size on the order of -4 ASTM according to ASTM E112 dated 2021. The initial beta treatment thus effectively eliminated the abnormal grain growth prior to final die forging. The deformation during the finishing die-making process allowed the grains to recrystallize, resulting in a completely regenerated and homogeneous microstructure.

[0057] Another Ti-6Al-4V alloy billet with a transus of 1000°C and dimensions of diameter = 80mm, h=70mm and r=8mm, underwent a beta treatment of 45 min followed by slow cooling, then a finishing die-forging at a temperature of 850°C. Some areas show significant tears in and under the surface (example 3).

[0058] Another Ti-6Al-4V alloy billet with a transus temperature of 1000°C and dimensions of diameter = 80 mm, height = 70 mm, and thickness = 8 mm, underwent a 45-minute beta heat treatment followed by water quenching and then a finishing die forging at a temperature of 850°C (Example 4). [It is observed that the intergranular decohesion of Example 3 is still present but greatly reduced. Thus, water quenching prevented surface and subsurface tears and reduced intergranular decohesion.]

Claims

1. Method for manufacturing a part made of β-treated titanium alloy without abnormally growing beta grains, characterized in that It comprises the following successive steps: a) - first heat treatment of a titanium alloy blank at a core temperature of the blank above the transus temperature β of the titanium alloy so as to obtain a β-treated blank; b) - final deformation step of the β-treated blank, this final deformation step being carried out at a core temperature of the blank below the transus temperature β of the titanium alloy with a local plastic deformation level ≥ 0.1 and with a plane deformation level ≤1 so as to obtain a titanium alloy part; c) - second heat treatment of the titanium alloy part at a core temperature of the part above the transus temperature β of the titanium alloy so as to obtain a β-treated titanium alloy part.

2. Manufacturing process according to claim 1, characterized in that Titanium alloy is a titanium alloy containing aluminum, advantageously a titanium alloy containing aluminum and vanadium, more advantageously the Ti-6Al-4V alloy.

3. A method according to any one of claims 1 or 2, characterized in that it includes an intermediate step a1) between steps a) and b), of water quenching the treated blank β ​​obtained in step a) and in that step b) is implemented on the processed draft β obtained in step a1).

4. A method according to any one of claims 1 to 3, characterized in that the level of local plastic deformation of step b) is ≥ 0.

2.

5. A method according to any one of claims 1 to 4, characterized in that The titanium alloy part is intended for aeronautics; advantageously, it is an aeronautical structural part, particularly for airplanes.

6. A method according to any one of claims 1 to 5, characterized in that the core blank temperature during step a) is at least 14°C higher than the transus β temperature of the titanium alloy, advantageously at least 20°C higher than the transus β temperature of the titanium alloy, more advantageously the temperature is greater than or equal to the transus β temperature of the titanium alloy + 25°C.

7. A method according to any one of claims 1 to 6, characterized in that step a) has a duration of at least 20 minutes, advantageously at least 30 minutes, in particular at least 45 minutes, more advantageously it is 1 hour.

8. A method according to any one of claims 1 to 7, characterized in that step b) consists of a final forging, advantageously a die-finishing.

9. A method according to any one of claims 1 to 8, characterized in thatit includes a step a0, prior to step a), of deformation of the titanium alloy blank, in particular by forging, advantageously at a core blank temperature lower than the transus temperature β of the titanium alloy.

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