EP2424688A1

EP2424688A1 - Method for producing elongate products made of titanium

Info

Publication number: EP2424688A1
Application number: EP10718244A
Authority: EP
Inventors: Christophe Delaunay; Alain Honnart; Volkter GÜTHER; Rüdiger FOX
Original assignee: GfE Metalle und Materialien GmbH; PFW Aerospace GmbH; Cefival
Current assignee: CEFIVAL; GfE Metalle und Materialien GmbH; PFW Aerospace GmbH
Priority date: 2009-04-30
Filing date: 2010-04-23
Publication date: 2012-03-07
Anticipated expiration: 2030-04-23
Also published as: CN102438764B; CN102438764A; EP2424688B8; JP2012525497A; FR2944983B1; FR2944983A1; KR20120037378A; WO2010125253A1; UA104024C2; RU2011148086A; RU2541251C2; WO2010125253A8; EP2424688B1

Abstract

The invention relates to a method for producing elongate products made of titanium or a titanium alloy, or blanks of such products, that comprises preparing a mass of titanium or titanium alloy material (10), melting said mass using an electric arc in a skull melting process (20), casting one or more ingots having a substantially cylindrical shape and a diameter of less than about 300 mm from the molten mass (30), and extruding one or more of said ingots at a temperature between 800 and 1200°C using an extrusion press (40). The invention can be used in the field of aeronautics, for example.

Description

PROCESS FOR PRODUCING TITANIUM EXTENSION PRODUCTS

The invention relates to a method for manufacturing elongated products of titanium material, or titanium alloy, or blanks of such products.

The term "elongate product" here refers to a metal part that has substantially smaller or even much smaller cross-sectional dimensions than its length.

Elongated products include metal parts, the production of which usually comprises at least one spinning operation. The elongated product qualification is however not reserved for such parts.

The elongated products more particularly comprise the metal parts resulting from a spinning operation, and comprise the profiled parts, including the hollow profiles and the tubes.

The term "roughing" must be understood here in a rather broad way. It denotes an unfinished elongated product whose overall shape corresponds essentially to the appearance of the finished elongated product. This implies that an elongated product blank is an elongate metal piece.

This does not exclude the subsequent adaptation of the shape of this blank, for example by machining, nor the modification of this general shape, for example by bending, folding, or any other plastic deformation. Rather, it should be understood that a "blank" of an elongate product is an elongated piece that can undergo different shaping, machining or surface treatments to give rise to a finished product.

The areas of use of elongated products made of titanium or titanium alloy are numerous. They include in particular aeronautical and aerospace construction.

Standards exist that govern the metallurgical quality of these products. The quality required depends on the intended application.

For example, in the particular case of aeronautical construction, high quality is required because of the dramatic consequences that would result from the failure of a product.

The respect of fixed qualities is not limited to the aeronautical field: in practice, most applications require minimum metallurgical qualities, whether these are subject to standards or not. And obtaining high quality products is not restricted to aeronautics and aerospace.

In addition to quality requirements, cost and availability requirements are now almost as high. In other words, it is not enough to know how to manufacture a product meeting quality requirements, but it must be possible to do so at a satisfactory cost and in sufficient quantity to satisfy the market.

This is why we are constantly looking for less expensive manufacturing processes that make it possible to produce products of at least equal quality. Conventional processes begin with the preparation of a mass of titanium material, which mass may comprise titanium sponges, titanium chips, titanium scrap (sometimes referred to as "titanium scrap" by abuse of language). and / or more generally recycled titanium material.

This mass of titanium material is then melted and cast into a single ingot, which has a large diameter.

In these conventional processes, different techniques can be implemented to achieve the melting / casting of the titanium mass.

Electron bombardment fusion, also referred to as "Electron beam furnace", is suitable for melting a mixture of titanium sponge and recycled material (scrap) as a raw material. Recycled materials being less expensive than titanium sponges, it is understandable economic interest that can take such a process.

Plasma torch fusion and cold crucible electron bombardment are newer techniques that provide more continuous casting and the ability to melt a larger proportion of titanium scrap. These techniques are thus more economical than conventional electron bombardment fusion.

With these conventional melting processes, the casting of the melt is gradual and quite slow. Generally, this melt flows in an ingot mold, little by little, by overflow effect of the melting tank, as the material is melted. The slowness and progressivity of the casting, resulting mainly from limits of fusion techniques, lead to casting defects in the ingot.

In order to meet high metallurgical requirements, for example for safety parts in the aeronautical field, it is necessary to remelt the ingot obtained after the first melting / casting and to cast a new one. Successive mergers improve the metallurgical quality of the ingot.

This reflow / casting is conventionally performed by the technique of remelting by vacuum arc, also called "VAR" (English "vacuum arc remelting"). The ingot obtained after the first melting constitutes an electrode which will gradually be melted, and simultaneously cast into an ingot of adjacent diameter, continuously. In practice, the diameter of the new ingot is about 10 to 20% greater than the diameter of the consumable electrode, that is to say of the first ingot.

It should be noted that certain standards, such as the United States of America standard AMS 4945, for use in the field of aircraft construction, require this reflow "VAR".

This "double fusion" is expensive. Also the founders have become accustomed to casting ingots of large diameter, practically between 500 and 1000 mm, noting that the volume cost decreases with increasing diameter of the cast ingot. In other words, the large diameter ingots are of lower cost, for a given volume of material.

In order to overcome the disadvantages of conventional (first) melting techniques, which are mainly the slowness and progressivity of melting / casting, a vacuum arc fusion technique has more recently been developed. and in autocreuset mode, also referred to as "skull melting" (literally "carapace fusion" in French). By autocreative mode is meant a melting process in which the furnace crucible is cooled so that a melt shell is formed over it, here titanium, or additional crucible, isolating the remainder of the melt from the furnace. oven crucible.

Part of the mass of titanium to be melted is placed in a crucible, while the other part of this mass takes the form of a consumable electrode. The whole of the titanium mass will be melted thanks to an electric arc generated between the electrode and the crucible then put to the bath temperature.

The melt is then poured into one or more ingot molds, at a time, by inclination of the crucible.

The "skull melting" allows rapid casting, in one go, batch (inclination), of the entire mass of melt. This can make it possible to avoid casting defects related to the slowness and progressivity of the older fusion techniques.

For economic reasons, it is usual to sink a single large ingot.

The "skull melting" allows the fusion of sponges of titanium as well as recycled materials, indifferently.

A further advantage is that the metal matrix that forms in contact with the crucible can be easily, or even directly, reused as a new electrode.

For most of the elongated products desired, the capacity of the current presses does not make it possible to spin directly the ingots obtained after reflow "VAR" or fusion "skull melting", because of too large diameter of the ingot.

One or more forging diameter reduction operations are required to convert the large diameter ingot into one or more billets of a diameter suitable for the spinning press and the desired elongated product.

For example, an ingot from a "VAR" remelting, or a "skull melting", may have a diameter of about 600 millimeters and be converted by successive forging operations into billets of about 120 millimeters diameter, or a diameter reduction by forging of the order of 25 (2500%).

It should be noted that the forging significantly improves the metallurgical quality of the billets, so that it is systematically implemented after melting (VAR, skull melting or others)

Additional operations, for example machining (to remove a thin surface layer of the billet forged or "peeling"), or finishing may, if necessary, also be implemented prior to spinning.

In summary, a typical manufacturing range of elongated high quality titanium or titanium alloy products from a titanium mass comprises the following operations: - melting of this mass of titanium, or alloy of titanium, titanium, and casting of a single ingot, of large diameter;

- Reflow "VAR" of this single ingot into a single ingot, also large diameter; this step being practically obligatory when the previous merger was not performed by "skull melting"; this reflow may be imposed by aeronautical standards. - preparing one or more billets for spinning from the large diameter ingot, including one or more forging operations;

- Spinning spinning of these billets to obtain elongated products of almost definitive form;

One or more surface treatment operations and / or altering the overall appearance of the elongated product can then be implemented to obtain the finished elongated product.

This range of manufacture is only very partially satisfactory, particularly in terms of cost, elongated product manufacturing time, and product availability.

The Claimants have sought to improve the situation.

The proposed method is directed to a method of manufacturing elongated products of titanium or titanium alloy, or blanks of such products, comprising the preparation of a mass of titanium material or titanium alloy, the melting of this mass. by electric arc and autocreuset mode, the casting of one or more ingots of substantially cylindrical shape and diameter less than about 300 mm from the melt, and then spinning one or more of these ingots at a temperature of between 800 ⁰ C and 1200 ⁰ C by means of a spinning press.

Such a method makes it possible to obtain healthy elongate products, that is to say substantially devoid of any casting defect, and of a mechanical strength, in particular as measured by tensile tests, at least equal to the products. obtained by conventional or currently known methods. By way of example, this method makes it possible to obtain elongated products of comparable quality to the products in accordance with the aeronautical standards currently in force, at least with regard to strength properties, for example the United States of America AMS 4935 or AMS 4945.

This process also offers a manufacturing cost of the product potentially lower than the manufacturing cost of conventional or currently known processes, as well as a shortened manufacturing time, partly related to the absence of any forging operation, and more generally to significant reduction of the diameter of ingots cast prior to the spinning operation and the simultaneous casting of several ingots.

The proposed method improves the availability of elongated products obtained, in particular due to a simplification of the manufacturing range and the possibility of using in the mass of titanium or prepared titanium alloy a large proportion of recycled material.

Other features and advantages of the invention will appear on examining the detailed description below, and the attached drawings in which:

FIG. 1 is a diagram of steps illustrating the method according to the invention,

FIG. 2 is a diagram of steps illustrating a variant of the method of FIG.

FIG. 3 is a diagram of steps illustrating a complementary method that can be implemented in addition to the methods of FIGS. 1 and 2. The attached drawings may not only serve to complete the invention, but also contribute to its definition, if any.

Figure 1 illustrates a method of manufacturing elongated products of titanium, or titanium alloy, or blanks of products of this type.

The process of FIG. 1 comprises an operation for preparing a mass of titanium material or a titanium alloy, an operation of melting this mass by an electric arc and in a self-heating mode, a casting operation of a or more ingots of substantially cylindrical shape and of diameter less than about 300 mm from the melt, then a spinning operation 40 of one or more of these ingots at a temperature between

800 ⁰ C and 1200 ⁰ C by means of a spinning press. Optionally, the elongated products resulting from this spinning step may undergo one or more finishing or semi-finishing steps 50.

The process of Figure 1 begins with an operation for preparing a mass of titanium or titanium alloy 10. The chemical composition of this mass is in accordance with the desired shade for the elongate product. For example, the chemical composition of this mass may be intended to obtain a TA6V4 alloy, or equivalent, as mentioned in the United States of America AMS 4935, or TA3V2.5, or equivalent, as mentioned in US Pat. the United States of America standard AMS 4945.

These alloys are particularly used in the aeronautical field, for which strict standards require a high metallurgical quality of the products. Their use is not limited to this sector of activity. And the implementation of the method of FIG. 1 is not limited either. to these particular alloys, but on the contrary extends to many different titanium compositions, depending in particular the intended application, for example T40, T60 or others.

This mass may include titanium sponge, titanium falls or titanium alloy, called ^w scrap "in English, titanium shavings or titanium alloy, of all or part of a shell or pocket or gangue, resulting from a fusion "skull melting", or more generally titanium material recycled in any form.The composition of the recycled material is controlled with respect to its quality and its chemical composition.

The recycled elements can come from milling, processed recycled materials intended for the titanium industry for remelting, machining residues of titanium or titanium alloy parts, or other.

These recycled materials may have many different chemical compositions, for example according to the desired shade for the elongated product, but not necessarily. These materials may correspond to the alloys mentioned above.

The recycled elements have an availability and a mass cost, that is to say a cost per kilogram of material, less than titanium sponges, so that it is advantageous to favor the use.

The mass of titanium or titanium alloy of the preparation step 10 may also comprise shading and / or alloying elements in proportions which depend on the continuation of the process, the intended application, and / or the desired shade for the elongate product. The process of FIG. 1 is continued by an electric arc melting and autocreative operation of the mass of titanium material or titanium alloy prepared in step 10.

That is to say, this fusion is done in the form of a fusion "skull melting".

A "skull melting" melting is carried out by means of an oven comprising a vacuum box and an appropriately shaped crucible housed inside the box.

A consumable electrode is mounted inside the box while titanium material is loaded into the crucible. A large potential difference is generated between the electrode and the crucible. When this potential difference reaches a certain threshold, a high energy level electric arc is created between the low end of the electrode and the titanium material located in the crucible.

In practice, the electrode can be mounted on a vertical piece that moves up and down in the box.

When the electrode is fully melted, the molten titanium mass present in the crucible can be cast, in one go, in one or more molds of selected shape, here of circular section and diameter less than 300 mm, placed at the inside the box. This casting is therefore very fast: it can for example be performed by tilting the crucible. The "skull melting" is thus a technique of fusion / batch casting.

During this melting / casting, a portion of the molten titanium mass solidifies at the interface with the crucible and forms a titanium gangue that protects the molten titanium from any pollution by other elements present in the crucible or by the crucible itself. In other words, this gangue forms an additional crucible arranged in the crucible materially provided in the furnace (melting autocreuset). After cooling, this gangue can be used as a consumable electrode for a new melting, which is interesting in terms of costs. The furnace crucible may be shaped so that the gangue has a shape adapted to its subsequent consumable electrode function.

The mass of titanium prepared in step 10 advantageously comprises the gangue, or shell, resulting from the melting and casting by "skull melting" of a previous titanium mass.

Also advantageously, the titanium mass prepared in step 10 comprises a large proportion of recycled titanium material.

Preferably, the titanium mass of the operation 10 comprises exclusively one or more skull shells, recycled material and the necessary alloying or shading elements, in appropriate proportion.

In other words, the process for preparing the mass of titanium or titanium alloy 10 mainly consists in producing a mixture of titanium or titanium alloy materials, most or all of which is in the mass, consists of recycled materials. Only the addition of shading elements may still be necessary.

The process of FIG. 1 therefore has a particular advantage in that it makes it possible to obtain high quality products at a lower cost than conventional processes, because of the almost exclusive use of recycled materials permitted by the use of electric arc melting and autocreative mode.

The temperature used for this melting operation, called the supercooling temperature, may depend on the composition of the mass of the preparation operation 10. A supercooling temperature greater than 1600 ^° C. makes it possible to melt this mass in most of the possible compositions. .

The process of FIG. 1 is continued by an ingot molding operation of generally circular section, the diameter of which is less than about 300 mm. Preferably the diameter of these ingots is less than 250 mm. This casting concerns the entire melt, all at once (in a "batch") and rapidly, for example by inclining the crucible containing the molten titanium mass

There is no lower limit to the diameter of ingots cast in operation 30. For economic reasons, however, it may be preferable to cast ingots larger than 100 mm in diameter.

There is no theoretical limit with respect to the length of ingots cast in step 30.

In practice, ingots are cast whose length is related to the length of the ingots to be spun in operation 40. For example, the length of an ingot cast in operation 30 may be chosen so as to be equal to a multiple of the length of a spinning ingot to the operation 40, to avoid material losses. More generally, the length of the ingot cast in the operation 30 may also be chosen to be equal to the sum of the lengths of ingot to be spun the spinning operation 40. Preferably, during the casting operation 30, as many cylindrical ingots are cast as the mass of titanium material melted in the operation 30 allows. We then take full advantage of the fact that the "skull melting" allows batch casting. The mass of titanium, or titanium alloy, cast in operation 20, and therefore the mass of titanium, or of titanium alloy, prepared for the operation 10 can be chosen, in quantity, as a function of number of ingots that one wishes to spin, and thus previously flow, and their size.

The diameter of each of the ingots cast in the operation 30 is less than 300 mm. Each of these ingots can then be spun in operation 40, without significant reduction of its diameter prior to this spinning operation.

A crushing operation can nevertheless take place between the casting of the operation 30 and the spinning of the operation 40. Although a decrease in diameter inevitably results from a crushing operation, this reduction is so small ( the order of a few tenths of a millimeter) that can not be considered as a significant reduction in the diameter of the ingot. In fact, the purpose of peeling is to remove the superficial layer of cast ingots, and as such can not be described as a diameter reduction operation, the object of which is by definition to reduce the diameter of the ingot in such a way that significant.

The cylindrical ingots cast in the operation 30 may have dimensions similar to each other, as regards their diameter and their length.

These ingots may also have different lengths and / or diameters, for example for the production of different elongate products. The diameter and the length of each of the ingots cast in the operation 30 may be chosen depending on the diameter and the length of the ingot (s) during operation 40. It is known to determine the length and the diameter of a spinning ingot according to the elongated product which it is desired to obtain at As a result of the spinning operation 40. In other words, the method of FIG. 1 makes it possible to obtain, after the casting operation 30, an ingot the dimensions of which are adapted to the spinning and whose dimensions can be calculated. depending on the dimensions of the desired elongate product.

On this point, the method of Figure 1 differs from conventional methods, which provide for the casting of a single ingot, in particular to reduce the mass cost of the cast ingot, and forging operations to reduce the diameter of the ingot. In other words, the diameter of the cast ingot is imposed in conventional methods (of the order of 400 to 600 mm), while this diameter can be chosen here.

It should be noted that, for dimensions of a product, elongated imposed, there is in practice a range of diameters and possible lengths for the ingot to spin 40. When elongated products of different sizes must be made according to the method of FIG. 1, it may be advantageous, where possible, to choose a diameter value of their respective ingot to be adapted to all of these products: it is thus possible to cast an ingot which can be cut to produce suitable ingots spinning different elongated products. This optimizes the management of inventories of ingots to spin.

It will also be noted that the method of FIG. 1 makes it possible to carry out as simply and for similar costs

(excluding raw material costs) larger diameter products and smaller diameter products. In the conventional processes, which require forging operations for diameter reduction, it is on the contrary more difficult and more expensive to produce products of small diameter, which products involve a higher reduction rate, which must most often be achieved by forging.

The presses currently in use do not allow the spinning of ingots longer than 1500 millimeters. In other words, the ingots cast in step 30 have a length less than 1500 millimeters, but could be longer in the case where more powerful presses came to light.

The process of FIG. 1 is completed by a hot spinning operation 40 of these cylindrical ingots on a spinning press to obtain an elongated product or a blank of such a product. The spinning operation 40 may be adapted to obtain a solid product or a hollow product.

The spinning temperature is greater than the so-called "transus β" temperature, which depends on the composition of the ingot.

The spinning operation 40 is carried out hot, at a temperature generally between 800 ⁰ C and 1200 ⁰ C. Preferably, the spinning is performed at a temperature above 900 ⁰ C to ensure good plasticity of the material and lower at 1150 ° C to avoid unnecessary energy expenditure while obtaining a suitable metallographic structure.

The spinning is carried out by means of a conventional spinning press equipped with a die and a punch. When a hollow elongated product has to be realized, it is also used a rod, also called "needle" (and in this case, the ingot has to have been previously drilled).

This spinning is carried out hot, in the presence of a lubricating agent. This lubricating agent generally comprises glass, that is to say the usual lubricating agent for conventional hot-spinning operations at a temperature above 900 ° C.

The process of FIG. 1 does not require any operation to reduce the diameter of the ingot cast during the operation 30 prior to the spinning operation 40.

It should be understood that this does not exclude that one or more particular operations, such as a peeling, different surface treatments or cutting, are performed on an ingot cast in step 30 to form the ingot to spin at step 40.

The metallurgical quality of the elongated product resulting from the spinning operation 40 is surprisingly comparable to the metallurgical quality of the products made according to the conventional methods, at least as regards the mechanical strength, in particular as measured by cold tensile test.

This comparable quality, obtained in the absence of any forging operation prior to the spinning operation 40, is largely related to the fact that the spinning has a beneficial and sufficient effect on the metallographic structure of the small diameter ingots which have been sunk.

The absence of any reduction operation of the ingot diameter resulting from the casting operation 30, in particular forging, prior to the spinning operation 40 also generates a reduction in the cost of manufacturing an elongate product. This absence also significantly reduces the manufacturing time of such a product.

The absence of a forging operation, or any other shaping operation, of the ingot prior to the spinning operation and the quality of the elongate product resulting from this spinning are such that, despite the small diameter of the cast ingots during the operation 30, the process of FIG. 1 is more economical than the methods of the state of the art, with regard to the final cost of the elongate product. Manufacturing lead times and availability are also improved over the state of the art.

The set of ingots cast in operation 30, or only a few of them, can be spun in parallel on several different presses, possibly after cutting, which significantly increases the productivity of the process. The cost of the elongated product obtained is reduced by the same amount.

Unlike conventional processes, the ingot cast in operation 30 is not remelted in the process of FIG. 1. However, the quality of the elongated product obtained after the spinning operation 40 is surprisingly, quite sufficient, with regard to the absence of casting defects and mechanical strength, compared to the products obtained after reflow "VAR", and without any forging operation, which forging is known to improve this quality .

Although some standards require vacuum reflow, such as "VAR" reflow, for high quality (or high performance) elongated products, the Applicant believes that that the products obtained by the method of Figure 1 are suitable for the applications envisaged in these standards, despite the absence of such a reflow.

FIG. 2 illustrates an alternative embodiment of the method of FIG. 1.

The spinning operation of the ingots 30 here comprises a casting operation of first ingots with a diameter less than 300 millimeters 300, then a "VAR reflow" operation 302 of these first ingots. In other words, each of the first ingots obtained after melting / casting "skull melting", or at least some of them, are individually subject to a "VAR" melting. These first ingots serve as consumable electrodes for this fusion.

The casting operation of ingots 30 finally comprises a casting operation of ingots to be spun from this second mass of melt, that is to say ingots of cylindrical shape and diameter less than 300 mm.

In a reflow "VAR", the casting is done gradually, as the consumable electrode melts. The diameter of the ingot obtained, or second ingot, is generally larger, of the order of 10 to 20% than the diameter of the electrode. Consequently, the diameter of the ingots cast in the operation 300 must take this increase into account, in particular so that the ingots to be spun in the operation 40 have a diameter of less than 300 mm without requiring any operation of diameter reduction.

FIG. 3 illustrates a finishing process 50, or semifinished, which can be carried out on elongate products made according to one of the methods of FIGS. 1 and 2. An elongated product resulting from the spinning operation 40 may undergo one or more of the following operations:

one or more heat treatments (in the oven) and one or more chemical (pickling for example) or physical surface treatments 51;

a straightening and straightening operation 52 intended to straighten the elongate product, with regard to its cross-section and general appearance;

a heat treatment operation 53; an operation of setting to length 54 by cutting or cutting,

a sand blasting operation 55, also known as sanding;

a shaping operation 56, a control operation 57 by one or more of the known non-destructive inspection techniques, such as ultrasound, radiography, eddy currents, or other,

- machining.

These operations are here presented in a purely indicative order and could very well be implemented in a different order.

The proposed method makes it possible to obtain elongated products of satisfactory quality, in accordance with the standards in force, without any forging operation, making the conventional "VAR" remelting operation optional and allowing a significant use of recycled material.

The proposed method is devoid of any forging operation. The Applicants have indeed realized, against all odds and contrary to ideas widely known in the art, that mechanical properties of comparable elongated products, or at the very least sufficient, can be obtained by spinning alone, making superfluous the beneficial action of a forging operation.

The proposed process has a lower manufacturing cost, shortened manufacturing times and increased product availability.

The invention is not limited to the methods described above, by way of example only. In particular :

The melting and casting operation 30 has been described as implementing a "skull melting" fusion. This fusion technique allows batch fusion / casting as opposed to progressive fusion / casting processes. Today, only this technique allows such a casting mode. However, the processes of Figures 1 and 2 could be implemented with a different melting technique provided that it has characteristics similar to the "skull melting", that is to say, to produce ingots capable of spinning, diameter less than 300 mm for a reasonable cost, preferably with use of a large amount of recycled material and with batch casting.

The reflow of the steps 302 and 304 could be carried out with different melting processes provided that they improve the metallographic quality of the ingots obtained and allow, for an acceptable cost, to obtain ingots of size adapted to the operation. spinning 40, that is to say of diameter less than 300 mm.

- At the end of the spinning operation 40 or, if appropriate, of the finishing operation 50, the elongated product obtained can undergo one or more forming operation, in particular forging, including to further reduce its section.

- One could consider more generally to spin ingots of diameter less than 300 mm, directly after they have undergone reflow "VAR" and without diameter reduction by prior forging, the first melting / casting having been carried out by any method , provided that the process in question allows the casting of ingots of suitable diameter, for a reasonable cost.

The elongated products obtained can be the subject of subsequent shaping, for example by bending.

The invention has been described with reference to the aeronautical field, in particular with regard to the standards in force in this field. This is due to the fact that this sector represents a large sector of application of elongated titanium products and that it requires a high quality of these products. This in no way limits the application of the method described to this particular line of business. Moreover, other sectors using titanium, or titanium alloy products, and demanding high quality products can refer to the standards established by the aerospace sector, without being part of this sector. The invention therefore also applies to these sectors. More generally, the invention is intended to be applicable in all areas requiring elongated titanium products for non-aeronautical and high quality applications, in addition to the aeronautical sector. On this point, the method according to the invention offers such flexibility and such cost reduction that it can offer new applications of elongated titanium products in non-aeronautical and / or general public areas. - Strictly speaking, elongate products made by the process of Figure 1 do not comply with the United States of America standard AMS 4935, for use in aircraft construction, in that they have not suffered several mergers, including one under vacuum. They nevertheless constitute products of comparable quality, in particular in terms of mechanical strength. The Applicant believes that these products could be used instead of the products defined in this standard or that this standard should evolve to include the products obtained by the process of Figure 1. Anyway, the quality of these products is such that many sectors that refer to said standard without being constrained can advantageously use them.

The invention encompasses all the variants that can be envisaged by those skilled in the art, in the light of the present description.

Claims

claims

A method of manufacturing elongated products made of titanium or titanium alloy, or blanks of such products, comprising the following steps: a) preparing a mass of titanium material or titanium alloy (10), b) melting this mass by electric arc and autocreuset mode (20), c) pour one or more ingots of substantially cylindrical shape and diameter less than about 300 mm from the melt (30), and d) spin one or several of these ingots at a temperature between 800 ⁰ C and 1200 ⁰ C by means of a spinning press (40).

The method of claim 1, wherein step c) comprises: flowing one or more first ingots from the melt (300); c2) melting each of said first ingots into a second mass of material titanium or respective titanium alloy (302), c3) casting one or more substantially cylindrical shaped ingots of diameter less than about 300 mm from each of the respective second titanium or titanium alloy material masses (304).

The method of claim 2, wherein step c1) comprises: c1) casting one or more substantially cylindrical ingots less than about 300 mm in diameter from the melt (300).

4. Method according to one of claims 2 and 3, wherein step c3) comprises: c31) casting a substantially cylindrical shaped ingot and of diameter less than about 300 mm from each of the second masses of material titanium or titanium alloy.

5. Method according to one of claims 2 to 4, wherein step c2) comprises: c21) melting at least a first ingot by electric arc under vacuum.

6. Method according to one of the preceding claims, wherein the diameter of the ingot to be spun is less than 250 mm.

7. Method according to one of the preceding claims, wherein the diameter of the ingot to be spun is greater than 100 mm.

8. Method according to one of the preceding claims, wherein step d) is carried out in the presence of a lubricating agent.

The process of claim 8, wherein the lubricating agent comprises glass.

10. Method according to one of the preceding claims, wherein the spinning temperature is between 900 ⁰ C and 1150 ⁰ C.

11. Method according to one of the preceding claims, wherein step c) comprises: cl) substantially cast the entire melt in step b) into spin ingots of substantially cylindrical shape and of diameter less than 300 mm.

12. Method according to one of the preceding claims devoid of any step of reducing the diameter of the ingots cast in step c) prior to step d).

13. Method according to one of the preceding claims comprising a step of cropping between steps c) and d).

14. Method according to one of the preceding claims, wherein the diameter of ingots cast in step c) is chosen according to the desired diameter of the elongated product made of titanium material or titanium alloy or the blank of this product .