RU2575276C2 - Treatment of alpha/beta titanium alloys - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to the metallurgy, namely to the methods of production of high strength α+β-titanium alloys, that can be used in engineering, where combination of high strength and corrosion resistance, and small weight is necessary. Method item forming out of α+β-titanium alloy containing in wt %: aluminium from 2.90 to 5.00, vanadium from 2.00 to 3.00, iron from 0.40 to 2.00, oxygen from 0.10 to 0.30, titanium and unintentional impurities - rest, includes cold pressure working of the alloy at temperature in range from ambient temperature to 500°F, and ageing at temperature in range from 700°F to 1200°F after cold pressure working without the solution treatment between cold pressure working and ageing.

EFFECT: alloy is characterised by high mechanical characteristics, high corrosion resistance, there are no high thermal and internal stresses or bucking.

29 cl, 12 dwg, 6 tbl, 3 ex

Description

FIELD OF TECHNOLOGY

[0001] The present invention relates to methods for producing high-strength alpha / beta (α + β) -titanium alloys and to products obtained by the described methods.

BACKGROUND

[0002] Titanium and titanium-based alloys are widely used due to the relatively high strength, low density and good corrosion resistance of these materials. For example, titanium and titanium-based alloys are widely used in the aerospace industry due to the high strength / weight ratio and corrosion resistance of these materials. It is known that one of the groups of titanium alloys that are widely used are alpha-beta (α + β) Ti-6Al-4V alloys having the following nominal composition, in percent by weight: aluminum - 6%; vanadium - 4%, oxygen - less than 0.20% and titanium - the rest.

[0003] Ti-6Al-4V alloys are one of the most common industrially produced titanium-based materials; their market share is estimated at over 50% of the total market share of titanium-based materials. Ti-6Al-4V alloys find a number of applications where a combination of high strength alloys at low-moderate temperatures, light weight and corrosion resistance is required. For example, Ti-6Al-4V alloys are used for the manufacture of aircraft engine components, aircraft structural components, fasteners, high-performance automotive components, components for medical devices, sports equipment, components for marine applications, as well as components for chemical process equipment .

[0004] Rolled products based on Ti-6Al-4V alloy are usually used either in the state annealed to improve ductility or in a solid solution and aged (OTP) state. Relatively lower strength of rolled products based on the Ti-6Al-4V alloy can be provided in the annealed condition to improve ductility. The term “annealed to improve ductility” as used herein refers to the state of a titanium alloy after what is called “annealing” heat treatment to improve ductility, in which the workpiece is annealed at elevated temperature (for example, 1200-1500 ° F / 649-816 ° C) for approximately 1-8 hours and cooled in still air. Annealing to improve ductility is performed after hot processing of the workpiece by pressure in the α + β-phase region. Alloys of Ti-6Al-4V annealed to improve ductility have a minimum prescribed tensile strength of 130 thousand psi. inch (896 MPa) and a minimum prescribed yield strength of 120 thousand psi. inch (827 MPa) at room temperature. See, for example, Aerospace Material Specifications (AMS) 4928 and 6931 A, which are incorporated herein by reference.

[0005] In order to increase the strength of Ti-6Al-4V alloys, the materials are usually heat treated by OPCS. Heat treatment of OTRS is usually carried out after hot processing of the workpiece by pressure in the α + β-phase region. OTRS is the heat treatment of a workpiece at an elevated temperature below the β-transformation temperature (for example, 1725-1775 ° F / 940-968 ° C) with a relatively short exposure time at a certain temperature (for example, about 1 hour) and then quickly quenching the workpiece with water or equivalent medium. The hardened billet is aged at elevated temperature (for example, 900-1200 ° F / 482-649 ° C) for about 4-8 hours and cooled in still air. Ti-6Al-4V alloys in the OPC state have a minimum prescribed tensile strength of 150-165 thousand psi. inch (1034-1138 MPa) and a minimum prescribed yield strength of 140-155 thousand psi. inch (965-1069 MPa) at room temperature, depending on the diameter or thickness of the product subjected to OTP. See, for example, AMS 4965 and AMS 6930A, which are incorporated herein by reference.

[0006] However, there are a number of limitations in the use of OPCS heat treatments to achieve the high strength of Ti-6Al-4V alloys. For example, the inherent physical properties of the material and the need for quick hardening during OPCS processing limit the dimensions and measurements of products that can achieve high strength and can exhibit relatively high thermal stresses, internal stresses, warping, and dimensional deformation. This invention relates to methods for treating certain α + β-titanium alloys to provide mechanical properties that are comparable to or superior to the properties of Ti-6Al-4V alloys in the OPCS state, but do not suffer from the limitations of the OPCS processing.

SUMMARY OF THE INVENTION

[0007] Embodiments of the invention described herein relate to methods of forming an article of an α + β-titanium alloy. The methods include cold pressure treatment of an α + β-titanium alloy at a temperature in the range from ambient temperature to 500 ° F (260 ° C) and, after the cold pressure step, aging of an α + β-titanium alloy at a temperature in the range of 700 ° F up to 1200 ° F (371-649 ° C). α + β-Titanium alloy contains, in weight percent, from 2.90% to 5.00% aluminum, from 2.00% to 3.00% vanadium, from 0.40% to 2.00% iron, from 0 10% to 0.30% oxygen, random impurities and titanium.

[0008] It is understood that the invention disclosed and described herein is not limited to the embodiments described in the Summary of the Invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The characteristics of the various non-limiting embodiments of the invention disclosed and described herein may be better understood when referring to the accompanying figures, including:

[0010] Figure 1 is a graph of the average tensile strength and the average yield strength as a function of the degree of cold working, quantitatively expressed as the relative decrease in cross-sectional area in percent (% RA) for cold drawn rods of an α + β-titanium alloy in the after state drawing

[0011] Figure 2 is a graph of average ductility quantified as percent elongation in tension for cold drawn bars of an α + β-titanium alloy in a post-drawing state;

[0012] Figure 3 is a graph of tensile strength and yield strength versus elongation as a percentage for bars of α + β-titanium alloy after cold working and immediately aging in accordance with embodiments of the methods described herein;

[0013] Figure 4 is a graph of average tensile strength and average yield strength versus average elongation for bars of an α + β-titanium alloy after cold forming and immediately aging in accordance with the methods described herein;

[0014] Figure 5 is a graph of the average tensile strength and the average yield strength versus aging temperature for bars of α + β-titanium alloy subjected to cold working up to 20% relative reduction in cross-sectional area and aging for 1 hour or 8 hours at a temperature;

[0015] Figure 6 is a graph of the average tensile strength and the average yield strength as a function of aging temperature for bars of α + β-titanium alloy subjected to cold working up to 30% relative reduction in cross-sectional area and aging for 1 hour or 8 hours at a temperature;

[0016] Figure 7 is a graph of the average tensile strength and the average yield strength versus aging temperature for bars of α + β-titanium alloy subjected to cold working up to 40% of the relative reduction in cross-sectional area and aging for 1 hour or 8 hours at a temperature;

[0017] Figure 8 is a graph of average elongation versus aging temperature for rods of α + β-titanium alloy subjected to cold working up to 20% relative reduction in cross-sectional area and aging for 1 hour or 8 hours at temperature;

[0018] Figure 9 is a graph of average elongation versus aging temperature for bars of an α + β-titanium alloy subjected to cold working to 30% relative reduction in cross-sectional area and aging for 1 hour or 8 hours at a temperature;

[0019] Figure 10 is a graph of average elongation versus aging temperature for bars of an α + β-titanium alloy subjected to cold working up to 40% relative reduction in cross-sectional area and aging for 1 hour or 8 hours at a temperature;

[0020] Figure 11 is a graph of the average tensile strength and the average yield strength versus aging time for bars of α + β-titanium alloy subjected to cold working up to 20% relative reduction in cross-sectional area and aging at a temperature of 850 ° F ( 454 ° C) or 1100 ° F (593 ° C); and

[0021] Figure 12 is a graph of average elongation versus aging time for bars of an α + β-titanium alloy subjected to cold working up to 20% relative reduction in cross-sectional area and aging at 850 ° F (454 ° C) or 1100 ° F (593 ° C).

[0022] The reader will appreciate the foregoing as well as other details when considering the following detailed description of various non-limiting embodiments in accordance with the present invention. The reader may also appreciate further details when implementing or using the embodiments described herein.

DETAILED DESCRIPTION OF NON-LIMITING EMBODIMENTS

[0023] It should be understood that the description of the disclosed embodiments has been simplified in order to illustrate only those features and characteristics that are necessary for a clear understanding of the described embodiments, while other features and characteristics are excluded for clarity. Specialists in this field when considering this description of the disclosed embodiments will understand that other features and characteristics may be desirable in a particular implementation or application of the described embodiments. However, since such other features and characteristics can be easily established and implemented by specialists in this field when considering this description of the disclosed embodiments and, therefore, are not necessary for a complete understanding of the described embodiments, a description of such features, characteristics and the like is not given here. . In this regard, it should be understood that the description set forth here is only an example and illustration of the described embodiments and is not intended to limit the scope of the invention defined by the claims.

[0024] In the present invention, unless otherwise indicated, all numerical parameters should be understood as being preliminarily and modifiable in all cases by the term “about”, within which numerical parameters have characteristic inherent variability due to the underlying measurement methods used to determine the numerical parameter values. As a last resort, and not as an attempt to limit the application of the theory of equivalents to the scope of the claims, each numerical parameter described in the description of the present invention should at least be construed in light of the number of significant digits recorded and by applying conventional rounding methods.

[0025] Also, any numerical range provided herein is intended to include all sub-ranges assigned to the specified range. For example, the range “from 1 to 10” is intended to include all subranges between (and including) the reduced minimum value of 1 and the reduced maximum value of 10, that is, with a minimum value equal to or greater than 1 and a maximum value equal to or less than 10. Any maximum numerical limitation, what is indicated here is intended to include all lower numerical limitations related to the given value, and any minimum numerical limitation indicated here is intended to include all higher numerical limitations, related to the given value. Accordingly, the applicant reserves the right to amend the present disclosure, including the claims, to specifically indicate any subband included in the ranges clearly indicated in this document. All such ranges are intended to be implicitly disclosed here, so that the modification of any clearly indicated any such ranges will comply with 35 U.S.C. §112, first paragraph, and 35 U.S.C. § 132 (a).

[0026] The grammatical singular and plural forms used herein are intended to include “at least one” or “one or more” unless otherwise indicated. Thus, the singular and plural forms are used here to name one or more (that is, “at least one”) of the objects of these grammatical forms. For example, “component” means one or more components, and thus, possibly more than one component is contemplated and can be applied or used in the implementation of the described embodiments.

[0027] Any patent, publication or other disclosure material that is indicated to be incorporated by reference is included in full, unless otherwise indicated, but only to the extent that the material included does not contradict existing definitions, statements or other disclosure material clearly set forth in this description. As such, and to the extent necessary, a clear description of the invention set forth herein supersedes any controversial material, incorporated herein by reference. Any material or part thereof, which is indicated to be included here by reference, but which contradicts the existing definitions, statements or other disclosure material set forth herein, is included only to the extent that there is no conflict between the material included and the existing disclosure material . The applicant reserves the right to amend the description of the present invention to directly indicate any object or part thereof, incorporated herein by reference.

[0028] The present disclosure includes descriptions of various embodiments. It should be understood that the various embodiments described herein are exemplary, illustrative, and non-limiting. Thus, the present disclosure is not limited to the description of various exemplary, illustrative and non-limiting embodiments. Rather, the invention is defined by claims that may be modified to indicate any features or characteristics explicitly or implicitly described in this disclosure or otherwise clearly or explicitly supported by it. In addition, the applicant reserves the right to amend the claims in order to legally refuse the features or characteristics that may be present in the prior art. Therefore, any such changes will comply with 35 U.S.C. §112, first paragraph, and 35 U.S.C. § 132 (a). Various embodiments of the invention disclosed and described herein may include, consist of, or essentially consist of features and characteristics, described differently herein.

[0029] The various embodiments described herein relate to thermomechanical methods of forming (forming) an article from an α + β-titanium alloy having a different chemical composition than Ti-6Al-4V alloys. In various embodiments, the α + β-titanium alloy contains, in weight percent, from 2.90 to 5.00 aluminum, from 2.00 to 3.00 vanadium, from 0.40 to 2.00 iron, from 0.20 up to 0.30 oxygen, random impurities and titanium. These α + β-titanium alloys (which are referred to herein as “Kosaka alloys”) are described in US Patent No. 5,980,655 to Kosaka, which is incorporated herein by reference. The nominal commercial composition of Kosaka alloys contains, in weight percent, 4.00 aluminum, 2.50 vanadium, 1.50 iron, 0.25 oxygen, random impurities and titanium, and may be called Ti-4Al-2.5V-1 alloy 5Fe-0.25O.

[0030] US Patent No. 5,980,655 (“655 patent”) describes the use of α + β thermomechanical processing for forming slabs of Kosaka alloy ingots. Kosaka alloys were developed as a cheaper alternative to Ti-6Al-4V alloys for use as a ballistic armor plate. α + β-Thermomechanical treatment described in the ′ 655 patent includes:

(a) forming an ingot having a Kosaka alloy composition;

(b) forging the ingot in the β region at a temperature above the β-transformation temperature of the alloy (for example, at a temperature above 1900 ° F (1038 ° C)) to obtain an intermediate slab;

(c) forging an intermediate slab in the α + β region at a temperature below the β-transformation temperature of the alloy, but in the α + β phase region, for example, at a temperature of 1500-1775 ° F (815-968 ° C);

(d) rolling the slab in the α + β region to a plate of finite thickness at a temperature below the β-transformation temperature of the alloy, but in the α + β-phase region, for example, at a temperature of 1500-1775 ° F (815-968 ° C); and

(e) heat treatment (annealing) to improve ductility at a temperature of 1300-1500 ° F (704-815 ° C).

[0031] Plates made in accordance with the methods described in the ′ 655 patent had ballistic properties comparable or superior to those of Ti-6Al-4V alloy plates. However, slabs made in accordance with the methods described in the '655 patent had tensile strengths at room temperature that were less than the high strengths achieved by Ti-6Al-4V alloys after treatment with OTRS.

[0032] Ti-6Al-4V alloys in the OPCS state can have a tensile strength of about 160-177 thousand psi. inch (1103-1220 MPa) and yield strength of approximately 150-164 thousand psi. inch (1034-1131 MPa) at room temperature. However, due to certain physical properties of Ti-6Al-4V, such as the relatively low thermal conductivity, tensile strength and yield strength that can be achieved with Ti-6Al-4V alloys by processing OPCs, they depend on the size of the Ti- alloy product. 6Al-4V subjected to OTPS processing. In this regard, the relatively low thermal conductivity of Ti-6Al-4V alloys limits the diameter / thickness of products that can be fully hardened / hardened using OPC processing, since the internal parts of products of this alloy of large diameter or thick section do not cool with sufficient speed during quenching so that mainly the alpha-stroke phase (α′-phase) is formed. Thus, processing OPCS of a Ti-6Al-4V alloy product of large diameter or thick section results in a product having a dispersion hardened surface layer surrounding a relatively weaker core without the same level of dispersion hardening, which can significantly reduce the overall strength of the product. For example, the strength of Ti-6Al-4V alloy products begins to decline for products having small dimensions (e.g. diameters or thicknesses) greater than about 0.5 inches (1.27 cm), and OPC processing is not beneficial for products of Small Ti-6Al-4V alloys larger than about 3 inches (7.62 cm).

[0033] The dependence of tensile strength on size for Ti-6Al-4V alloys in the OPCS state is manifested in a decrease in minimum strengths in accordance with an increase in product dimensions for material specifications such as AMS 6930A, in which the largest minimum strengths for Ti-6Al alloys -4V in the OPCS state corresponds to products with a diameter or thickness of less than 0.5 inches (1.27 cm). For example, AMS 6930A indicates a minimum tensile strength of 165 thousand psi. inch (1138 MPa) and a minimum yield strength of 155 thousand pounds / sq. inch (1069 MPa) for Ti-6Al-4V alloy products in an OPC state having a diameter or thickness of less than 0.5 inches (1.27 cm).

[0034] Furthermore, processing of the OPCS can cause relatively high thermal and internal stresses and lead to twisting of titanium alloy products during the hardening step. Despite these limitations, OPCS processing is the standard way to achieve high strength in Ti-6Al-4V alloys, since Ti-6Al-4V alloys usually do not deform in the cold, therefore, they cannot be subjected to effective cold working to increase strength. Not intending to be limited by theory, we believe that the absence of cold deformability / workability is mainly associated with the phenomenon of slip bands in Ti-6Al-4V alloys.

[0035] In the alpha phase (α phase) of Ti-6Al-4V alloys, coherent Ti ₃ Al particles (alpha-two) are released. These coherent precipitations of alpha-two (α ₂ ) increase the strength of the alloys, but because coherent precipitates shift as dislocations move during plastic deformation, these precipitates lead to the formation of pronounced planar slip bands in the microstructure of the alloys. In addition, it has been shown that Ti-6Al-4V alloy crystals form localized short-range order regions of aluminum and oxygen atoms, i.e., localized deviations from the homogeneous distribution of aluminum and oxygen atoms in the crystal structure. It is shown that these localized regions with reduced entropy contribute to the formation of pronounced planar slip bands in the microstructure of Ti-6Al-4V alloys. The presence of these microstructural and thermodynamic features in Ti-6Al-4V alloys can cause entanglement of slip of dislocations or otherwise interfere with slip of dislocations during deformation. When this happens, the slip is localized in the pronounced flat regions of the alloys, called slip bands. Slip bands lead to loss of ductility, crack nucleation and crack propagation, which leads to defects in Ti-6Al-4V alloys during cold working.

[0036] Therefore, Ti-6Al-4V alloys are usually pressure treated (for example, forged, rolled, drawn, etc.) at elevated temperatures, usually above the dissolution temperature (solvus) of the α ₂ phase. Ti-6Al-4V alloys cannot be effectively cold worked to increase strength due to the high probability of cracking (i.e., workpiece defects) during cold deformation. However, it has been unexpectedly discovered that Kosaka alloys have a significant degree of cold deformability / processability, as described in published US patent application No. 2004/0221929, which is incorporated herein by reference.

[0037] It has been found that Kosaka alloys do not exhibit slipping of bands during cold forming and, therefore, exhibit significantly less cracking during cold forming compared to Ti-6Al-4V alloy. Without intending to limit ourselves to theory, we believe that the absence of slip bands in Kosaka alloys may be due to minimization of the short-range order of aluminum and oxygen atoms. In addition, the stability of the α ₂ phase is lower in Kosaka alloys relative to alloys, for example, Ti-6Al-4V, as shown on equilibrium models for the dissolution temperature of the α ₂ phase (1305 ° F / 707 ° C for Ti-6Al-4V ( max 0.15 wt.% oxygen) and 1062 ° F / 572 ° C for Ti-4Al-2.5V-1.5Fe-0.25O as determined using Pandat software, CompuTherm LLC, Madison, Wisconsin , USA). As a result, Kosaka alloys can be cold worked to achieve high strength and maintain a healthy level of ductility. In addition, it was found that Kosaka alloys can be cold worked and aged to achieve increased strength and ductility only by cold working. In fact, Kosaka alloys can achieve strength and ductility comparable or superior to those of Ti-6Al-4V alloys in the OPCS state, but without the need for OTPS processing and without its limitations.

[0038] Generally, the term "cold forming" refers to the processing of an alloy by pressure at a temperature below that at which the plastic flow stress of a material is significantly reduced. Used here in connection with the described methods, the terms "cold forming", "subjected to cold forming", "cold forming" and the like or the term "cold" used in connection with a specific method of pressure processing or molding, refer to pressure treatment or the characteristics available after pressure treatment, as the case may be, at a temperature of not more than about 500 ° F (260 ° C). Thus, for example, a drawing operation performed on a Kosaka alloy billet at a temperature in the range from ambient temperature to 500 ° F (260 ° C) is considered here to be a cold pressure treatment. Also, the terms “molding”, “molding” and “deformation” are commonly used interchangeably herein, as are the terms “machinability”, “moldability”, “deformability”, and the like. It should be understood that the meaning of the terms "cold forming", "subjected to cold forming" and "cold forming" and the like in connection with the present invention is not intended to limit or limit the meaning of these terms in other contexts or in connection with other inventions.

[0039] In various embodiments, the methods described herein may include cold forming an α + β-titanium alloy at a temperature in the range of ambient temperature to 500 ° F (260 ° C). After the cold working operation, the α + β-titanium alloy can be aged at temperatures ranging from 700 ° F to 1200 ° F (371-649 ° C).

[0040] When a mechanical operation, such as, for example, a cold drawing passage, is described herein as being performed, performed, and the like. at a certain temperature or within a certain temperature range, this mechanical operation is performed on a workpiece that is at a certain temperature or within a certain temperature range at the beginning of a mechanical operation. During a mechanical operation, the temperature of the workpiece may vary from the initial temperature of the workpiece at the beginning of the mechanical operation. For example, the temperature of the workpiece may increase as a result of adiabatic heating or decrease as a result of conductive, convective and / or radiative cooling during the pressure treatment operation. The magnitude and direction of the temperature change from the initial temperature at the beginning of the mechanical operation may depend on various parameters, such as, for example, the level of processing performed on the workpiece, the degree of deformation with which pressure processing is performed, the initial temperature of the workpiece at the beginning of the mechanical operation, and ambient temperature .

[0041] When a thermal operation, such as heat treatment by aging, is described herein as being carried out at a certain temperature and for a certain period of time or within a certain temperature range and time range, this operation is performed for a certain time, keeping the workpiece at a temperature. The time periods described here for thermal operations, such as heat treatment by aging, do not include the duration of the rises and drops in temperature, which may depend, for example, on the size and shape of the workpiece.

[0042] In various embodiments, the α + β-titanium alloy can be cold worked at a temperature in the range from ambient temperature to 500 ° F (260 ° C) or in any sub-range, such as, for example, from ambient temperature to 450 ° F (232 ° C), from ambient to 400 ° F (204 ° C), from ambient to 350 ° F (177 ° C), from ambient to 300 ° F (149 ° C) , from ambient temperature to 250 ° F (121 ° C), from ambient temperature to 200 ° F (93 ° C) or from ambient temperature to 150 ° F (65 ° C). In various embodiments, the α + β-titanium alloy can be cold worked at ambient temperature.

[0043] In various embodiments, cold forming of an α + β-titanium alloy can be carried out using forming methods, including but not limited to: drawing, deep drawing, rolling, profiling, forging, extrusion pressing, pilgrim rolling, periodic rolling, rotational extrusion, shear rolling, hydroforming, embossing, crimping, impact extrusion, explosion stamping, rubber stamping, reverse extrusion, punching, rotational extrusion Lebanon, a bending tension, compression bending, electromagnetic forming, landing, embossing and combinations of any of them. From the point of view of the methods described herein, these forming methods give a curing to the α + β-titanium alloy when they are performed at temperatures not higher than 500 ° F (260 ° C).

[0044] In various embodiments, the α + β-titanium alloy may be cold worked until the relative cross-sectional area is reduced in the range of 20% to 60%. For example, an α + β-titanium alloy billet, such as, for example, an ingot, billet, bar, rod, pipe, slab or plate, can be plastically deformed, for example, during the operation of cold drawing, cold rolling, cold extrusion or cold forging, so that the cross-sectional area of the workpiece is reduced by a percentage in the range from 20% to 60%. For cylindrical workpieces, such as, for example, round ingots, billets, rods, rods and pipes, the relative decrease in the cross-sectional area is measured on a round or annular cross-section of the workpiece, which is usually perpendicular to the direction of movement of the workpiece through an exhaust die (die), extrusion die ( matrix) or the like. Similarly, the relative decrease in the cross-sectional area of rolled billets is measured on the cross-section of the billet, which is usually perpendicular to the direction of movement of the billet through the rolls of the rolling device or the like.

[0045] In various embodiments, the α + β-titanium alloy may be cold worked to relatively reduce the cross-sectional area in the range of 20% to 60% or in any sub-range thereof, such as, for example, 30% to 60% , from 40% to 60%, from 50% to 60%, from 20% to 50%, from 20% to 40%, from 20% to 30%, from 30% to 50%, from 30% to 40% or from 40% to 50%. The α + β-Titanium alloy can be cold worked to relatively reduce the cross-sectional area in the range from 20% to 60% without noticeable edge cracks or other surface cracks. Cold pressure treatment can be performed without any intermediate annealing to relieve stress. Thus, with the various embodiments of the methods described herein, it is possible to achieve a relative reduction in cross-sectional area of up to 60% without intermediate annealing to relieve stresses between successive cold forming operations, such as, for example, two or more passes through a cold drawing unit.

[0046] In various embodiments, the cold forming operation may include at least two deformation cycles, where each deformation cycle includes cold forming the α + β-titanium alloy to at least 10% relative reduction in cross-sectional area. In various embodiments, the cold forming operation may include at least two deformation cycles, where each deformation cycle includes cold forming the α + β titanium alloy to at least 20% relative reduction in cross-sectional area. In at least two deformation cycles, a relative reduction in cross-sectional area of up to 60% can be achieved without any intermediate annealing to relieve stresses.

[0047] For example, in a cold drawing operation, the bar may be cold drawn in the first pass at ambient temperature to more than 20% relative reduction in cross-sectional area. Having achieved more than 20% relative reduction in cross-sectional area, the cold drawn bar can then be subjected to a second cold drawing at ambient temperature to a second relative decrease in cross-sectional area greater than 20%. Two cold drawing passes can be performed without any intermediate annealing to relieve stress between the two passes. Thus, the α + β-titanium alloy can be cold worked using at least two deformation cycles to achieve a larger total relative reduction in cross-sectional area. In this embodiment, the cold forming operations, the forces required for cold deformation of the α + β-titanium alloy will depend on parameters, including, for example, the size and shape of the workpiece, the yield strength of the alloy material, and the degree of deformation (for example, a relative decrease in cross-sectional area) and a specific cold forming process.

[0048] In various embodiments, after the cold forming operation, the cold-pressed α + β-titanium alloy can be aged at a temperature in the range of 700 ° F to 1200 ° F (371-649 ° C), or in any sub-range thereof, such as, for example, from 800 ° F to 1150 ° F, from 850 ° F to 1150 ° F, from 800 ° F to 1100 ° F or from 850 ° F to 1100 ° F (i.e. 427-621 ° C, 454 -621 ° C, 427-593 ° C or 454-593 ° C). Heat treatment by aging can be performed at a temperature and for a time sufficient to provide a certain combination of mechanical properties, such as, for example, a certain tensile strength, a certain yield strength and / or a specific elongation. In various embodiments, heat treatment by aging can be performed for up to 50 hours at a temperature, for example. In various embodiments of the invention, the heat treatment with aging can be performed in the range from 0.5 to 10 hours at a temperature or in any sub-range thereof, such as, for example, from 1 to 8 hours at a temperature. Heat treatment with aging can be carried out in a temperature-controlled furnace, such as, for example, an open-type gas furnace.

[0049] In various embodiments, the methods described herein may further include a hot forming operation performed prior to the cold forming operation. The hot pressure treatment operation can be performed in the α + β-phase region. For example, a hot pressure treatment operation can be performed at a temperature in the range of 300 ° F to 25 ° F (167-15 ° C) below the β-transformation temperature of the α + β-titanium alloy. Typically, Kosaka alloys have a β-transformation temperature in the range of about 1765 ° F to 1800 ° F (963-982 ° C). In various embodiments, the α + β-titanium alloy may be hot worked at a temperature in the range of 1500 ° F to 1775 ° F (815-968 ° C) or in any sub-range thereof, such as, for example, 1600 ° F up to 1775 ° F, from 1600 ° F to 1750 ° F or from 1600 ° F to 1700 ° F (i.e. 871-968 ° C, 871-954 ° C or 871-927 ° C).

[0050] In embodiments comprising a hot forming operation before a cold forming operation, the methods described herein may further include optional annealing or heat treatment to relieve stresses between the hot forming operation and the cold forming operation. The hot-pressed α + β-titanium alloy can be annealed at a temperature in the range of 1200 ° F to 1500 ° F (649-815 ° C) or in any sub-range thereof, such as, for example, from 1200 ° F to 1400 ° F or from 1250 ° F to 1300 ° F (i.e. 649-760 ° C or 677-704 ° C).

[0051] In various embodiments, the methods described herein may include an optional hot forming operation performed in a β-phase region before a hot forming operation performed in an α + β-phase region. For example, a titanium alloy ingot may be hot-pressed in the β-phase region to form an intermediate article. The intermediate product can be subjected to hot pressure treatment in the α + β-phase region in order to develop the microstructure of the α + β-phases. After hot working, the intermediate can be annealed to relieve stress and then cold worked at a temperature in the range from ambient to 500 ° F (260 ° C). The cold-worked product may be aged at a temperature in the range of 700 ° F to 1200 ° F (371-649 ° C). Optional hot pressure treatment in the region of the β-phase is performed at a temperature above the β-transformation temperature of the alloy, for example, at a temperature in the range from 1800 ° F to 2300 ° F (982-1260 ° C) or in any sub-range thereof, such as, for example , from 1900 ° F to 2300 ° F or from 1900 ° F to 2100 ° F (i.e. 1038-1260 ° C or 1038-1149 ° C).

[0052] In various embodiments, the methods described herein can be characterized by forming an α + β-titanium alloy article having a tensile strength in the range of 155 thousand psi. inch to 200 thousand pounds / sq. inch (1069-1379 MPa) and elongation in the range from 8% to 20%, at ambient temperature. Also in various embodiments, the methods described herein can be characterized by forming an α + β-titanium alloy article having a tensile strength in the range of 160 thousand psi. inch to 180 thousand pounds / sq. inch (1103-1241 MPa) and elongation in the range from 8% to 20%, at ambient temperature. In addition, in various embodiments, the methods described herein can be characterized by forming an α + β-titanium alloy article having a tensile strength in the range of 165 thousand psi. inch to 180 thousand pounds / sq. inch (1138-1241 MPa) and elongation in the range from 8% to 17%, at ambient temperature.

[0053] In various embodiments, the methods described herein can be characterized by forming an α + β-titanium alloy article having a yield strength in the range of 140 thousand psi. inch to 165 thousand pounds / sq. inch (965-1138 MPa) and elongation in the range from 8% to 20%, at ambient temperature. In addition, in various embodiments, the methods described herein can be characterized by forming an α + β-titanium alloy article having a yield strength in the range of 155,000 psi. inch to 165 thousand pounds / sq. inch (1069-1138 MPa) and elongation in the range from 8% to 15%, at ambient temperature.

[0054] In various embodiments, the methods described herein can be characterized by forming an article of an α + β-titanium alloy having a tensile strength in any subband falling within the range of 155 thousand psi. inch to 200 thousand pounds / sq. inch (1069-1379 MPa), yield strength in any subrange falling within the limits of 140 thousand pounds / sq. inch to 165 thousand pounds / sq. inch (965-1138 MPa), and elongation in any subrange falling within the range from 8% to 20%, at ambient temperature.

[0055] In various embodiments, the methods described herein can be characterized by forming an α + β-titanium alloy article having a tensile strength of more than 155 thousand psi. inch, yield strength of more than 140 thousand pounds / sq. inch and elongation of more than 8%, at ambient temperature. An α + β-titanium alloy product formed in accordance with various embodiments may have a tensile strength of more than 166 thousand psi. inch, more than 175 thousand pounds / sq. inch, more than 185 thousand pounds / sq. inch or more than 195 thousand pounds / sq. inch at ambient temperature. An α + β-titanium alloy product formed in accordance with various embodiments may have a yield strength of more than 145 thousand psi. inch, more than 155 thousand pounds / sq. inch or more than 160 thousand pounds / sq. inch at ambient temperature. An α + β-titanium alloy product formed in accordance with various embodiments may have an elongation of more than 8%, more than 10%, more than 12%, more than 14%, more than 16% or more than 18% at ambient temperature.

[0056] In various embodiments, the methods described herein can be characterized by forming an α + β-titanium alloy article having a tensile strength, yield strength, and elongation at ambient temperature that are at least as large as the limit tensile strength, yield strength and elongation, at ambient temperature, for an otherwise identical product, consisting of an alloy of Ti-6Al-4V in the state after treatment for solid solution and aging (OTRS).

[0057] In various embodiments, the methods described herein can be used for thermomechanical processing of α + β-titanium alloys containing, consisting of or consisting essentially of, in weight percent, from 2.90% to 5.00% aluminum, from 2 , 00% to 3.00% vanadium, from 0.40% to 2.00% iron, from 0.10% to 0.30% oxygen, random elements and titanium.

[0058] The concentration of aluminum in α + β-titanium alloys thermomechanically processed in accordance with the methods described herein may be in the range from 2.90 to 5.00 weight percent or in any sub-band thereof, such as, for example, from 3, 00% to 5.00%, from 3.50% to 4.50%, from 3.70% to 4.30%, from 3.75% to 4.25% or from 3.90% to 4.50 % The concentration of vanadium in α + β-titanium alloys thermomechanically processed in accordance with the methods described here may be in the range from 2.00 to 3.00 weight percent or in any sub-range thereof, such as, for example, from 2.20% to 3.00%, from 2.20% to 2.80%, or from 2.30% to 2.70%. The concentration of iron in α + β-titanium alloys thermomechanically processed in accordance with the methods described herein may be in the range from 0.40 to 2.00 weight percent or in any subrange thereof, such as, for example, from 0.50% to 2.00%, from 1.00% to 2.00%, from 1.20% to 1.80%, or from 1.30% to 1.70%. The oxygen concentration in α + β-titanium alloys thermomechanically processed in accordance with the methods described herein may be in the range from 0.10 to 0.30 weight percent or in any sub-range thereof, such as, for example, from 0.15% to 0.30%, from 0.10% to 0.20%, from 0.10% to 0.15%, from 0.18% to 0.28%, from 0.20% to 0.30%, from 0.22% to 0.28%, from 0.24% to 0.30%, or from 0.23% to 0.27%.

[0059] In various embodiments, the methods described herein can be used to thermomechanically treat an α + β-titanium alloy containing, consisting of or consisting essentially of a nominal composition: 4.00 weight percent aluminum, 2.50 weight percent vanadium, 1, 50 weight percent iron and 0.25 weight percent oxygen, titanium and random impurities (Ti-4Al-2.5V-1.5Fe-0.25O). An α + β-titanium alloy with a nominal composition of Ti-4Al-2,5V-1,5Fe-0.25O is commercially available as ATI 425 ^® alloy from Allegheny Technologies Incorporated.

[0060] In various embodiments, the methods described herein can be used to thermomechanically treat α + β-titanium alloys containing, consisting or consisting essentially of titanium, aluminum, vanadium, iron, oxygen, random impurities and less than 0.50 weight percent of any other intentionally introduced alloying elements. In various embodiments, the methods described herein can be used to thermomechanically treat α + β-titanium alloys containing, consisting or consisting essentially of titanium, aluminum, vanadium, iron, oxygen, and less than 0.50 weight percent of any other elements, including intentionally introduced alloying elements and random impurities. In various embodiments, the maximum level of all elements (random impurities and / or intentionally introduced alloying additives) other than titanium, aluminum, vanadium, iron, and oxygen may be 0.40 weight percent, 0.30 weight percent, 0.25 weight percent, 0.20 weight percent or 0.10 weight percent.

[0061] In various embodiments, the α + β-titanium alloys processed as described herein may comprise, consist of, or consist essentially of a composition in accordance with AMS 6946A, Section 3.1, which is incorporated herein by reference and which defines the composition given in Table 1 (in weight percent).

[0062] In various embodiments, the α + β-titanium alloys processed as described herein may include various elements other than titanium, aluminum, vanadium, iron, and oxygen. For example, such other elements and their weight percentages may include, but not necessarily limited to, one or more of the following elements: (a) chromium, 0.10% maximum, usually from 0.0001% to 0.05%, or up to about 0 , 03%; (b) nickel, 0.10% maximum, usually from 0.001% to 0.05% or up to about 0.02%; (c) molybdenum, 0.10% maximum; (d) zirconium, 0.10% maximum; (e) tin, 0.10% maximum; (f) carbon, 0.10% maximum, usually from 0.005% to 0.03% or up to about 0.01%; and / or (g) nitrogen, 0.10% maximum, usually from 0.001% to 0.02%, or up to about 0.01%.

[0063] The methods described herein can be used to form products, such as, for example, tickets, rods, rods, wire, tubes, pipes, slabs, plates, structural elements, fasteners, rivets and the like. In various embodiments, the methods described herein provide articles having a tensile strength in the range of 155,000 psi. inch to 200 thousand pounds / sq. inch (1069-1379 MPa), yield strength in the range from 140 thousand pounds / sq. inch to 165 thousand pounds / sq. inch (965-1138 MPa) and elongation in the range from 8% to 20%, at ambient temperature, and having a minimum size (e.g. diameter or thickness) of more than 0.5 inches, more than 1.0 inch, more than 2.0 inches, more than 3.0 inches, more than 4.0 inches, more than 5.0 inches or more than 10.0 inches (i.e. more than 1.27 cm, 2.54 cm, 5, 08 cm, 7.62 cm, 10.16 cm, 12.70 cm or 24.50 cm).

[0064] In addition, one of the various advantages of the embodiments of the methods described herein is that high-strength articles of α + β-titanium alloy can be formed without size restrictions, which is an inherent limitation of OPCS processing. As a result, the methods described herein can produce articles having a tensile strength of more than 165 thousand psi. inch (1138 MPa), yield strength of more than 155 thousand psi. inch (1069 MPa) and elongation of more than 8%, at ambient temperature, without inherent limitation on the maximum value of the small size (for example, diameter or thickness) of the product. Therefore, the maximum size is limited only by the size limitations of the cold forming equipment used to perform cold forming in accordance with the embodiments described herein. In contrast, OTPS processing imposes an inherent restriction on the maximum value of the small size of the product, which can achieve high strength, for example, 0.5 inches (1.27 cm) maximum for Ti-6Al-4V products having a tensile strength at tensile of at least 165 thousand pounds / sq. inch (1138 MPa) and yield strength of at least 155 thousand pounds / sq. inch (1069 MPa) at room temperature. See AMS 6930A.

[0065] In addition, the methods described herein can produce α + β-titanium alloy products having high strength with low or zero thermal stresses and better dimensional tolerances than high strength products obtained using OPC processing. Cold drawing and direct aging in accordance with the methods described here do not lead to problematic internal thermal stresses, do not cause product twisting and do not cause dimensional distortion of products, which is known to occur when using OPCS for processing products from α + β-titanium alloy.

[0066] The method described herein can also be used to form articles of α + β-titanium alloy having mechanical properties that fall into a wide range, depending on the level of cold working and the time / temperature of aging. In various embodiments, the tensile strength can be in the range of about 155 thousand psi. inch to over 180 thousand pounds / sq. inch (from about 1069 MPa to over 1241 MPa), the yield strength can be in the range from about 140 thousand pounds / sq. inch to about 163 thousand pounds / sq. inch (965-1124 MPa), and elongation may be in the range from about 8% to over 19%. Various mechanical properties can be achieved through various combinations of cold working and aging. In various embodiments, increased levels of cold forming (for example, reduced cross-section) may correlate with increased strength and reduced ductility, while increased aging temperatures may correlate with reduced strength and increased ductility. Thus, the cold forming and aging cycles can be specified in accordance with the embodiments described herein in order to achieve controlled and reproducible levels of strength and ductility of α + β-titanium alloy products. This allows you to make products from α + β-titanium alloy having specified mechanical properties.

[0067] The illustrative and non-limiting examples given below are intended to further describe various non-limiting embodiments without limiting the scope of embodiments of the invention. Persons who are specialists in this field, it will be understood that variations of the Examples are possible within the scope of the invention defined by the claims.

EXAMPLES

Example 1

[0068] Cylindrical 5.0 inch diameter billets from an alloy of two different melts having an average chemical composition shown in Table 2 (excluding random impurities) were hot rolled in the α + β phase at 1600 ° F (871 ° C) with the formation of round bars with a diameter of 1.0 inch.

[0069] The 1.0 inch diameter round rods were annealed at 1275 ° F for one hour and cooled in air to ambient temperature. The annealed rods were cold worked at ambient temperature using drawing operations to reduce the diameter of the rods. The degree of cold pressure treatment performed on the rods during cold drawing operations was quantified as a reduction in the circular cross-sectional area in percent for round rods during cold drawing. The percentage of cold working was 20%, 30%, or 40% reduction in cross-sectional area (RA). Drawing operations were performed using one drawing pass for a 20% reduction in cross-sectional area and two drawing passes for a 30% and 40% reduction in cross-sectional area without intermediate annealing.

[0070] Tensile strength (UTS), yield strength (YS) and elongation (%) were measured at ambient temperature for each cold drawn rod (20%, 30% and 40% RA) and for 1 inch diameter rods that not cold drawn (0% RA). The averaged results are shown in Table 3 and in Figures 1 and 2.

[0071] The tensile strength typically increased with increasing levels of cold working, while the elongation usually decreased with increasing levels of cold working to about 20-30% cold working. Alloys subjected to cold working up to 30% and 40% retained approximately 8% elongation with tensile strengths greater than 180 thousand psi. inch and approaching 190 thousand pounds / sq. inch. Alloys subjected to cold working pressure up to 30% and 40%, also had yield strengths in the range of 150 thousand pounds / square. inch to 170 thousand pounds / sq. inch.

Example 2

[0072] Cylindrical billets with a diameter of 5 inches having an average melt chemical X shown in Table 1 (β-transformation temperature of 1790 ° F) were thermo-mechanically processed as described in Example 1 to form round rods having a degree of cold working 20%, 30% or 40% reduction. After cold drawing, the rods were immediately subjected to aging using one of the aging cycles shown in Table 4, after which they were cooled in air to ambient temperature.

[0073] Tensile strength, yield strength and elongation were measured at ambient temperature for each cold drawn and aged bar. Raw data is shown in Figure 3, and the averaged data is presented in Figure 4 and in Table 5.

[0074] Cold drawn and aged alloys exhibited a range of mechanical properties depending on the level of cold working and the time / temperature cycle of the aging treatment. The tensile strength ranged from about 155 thousand pounds / sq. inch to over 180 thousand pounds / sq. inch. The yield strength ranged from about 140 thousand pounds / sq. inch to about 163 thousand pounds / sq. inch. Elongation ranged from about 11% to over 19%. Accordingly, various mechanical properties can be achieved through various combinations of cold forming level and aging treatment.

[0075] Elevated levels of cold forming typically correlate with increased strength and reduced ductility. Elevated aging temperatures usually correlate with reduced strength. This is shown in Figures 5, 6 and 7, which depict graphs of the dependence of strength (average UTS and average YS) on temperature for the degree of cold working pressure of 20%, 30 and 40% reduction, respectively. Elevated aging temperatures usually correlate with increased ductility. This is shown in Figures 8, 9 and 10, which depict graphs of the dependence of the average relative elongation on temperature for the degree of cold working pressure of 20%, 30% and 40% reduction, respectively. The duration of the aging treatment does not seem to have a significant effect on the mechanical properties, as shown in Figures 11 and 12, which depict graphs of the strength and elongation, respectively, over time for a degree of cold working of 20% compression.

Example 3

[0076] Cold drawn round rods having the chemical composition of heat X, shown in Table 1, with diameters of 0.75 inches, and processed as described in Examples 1 and 2 to 40% reduction during the drawing operation, were tested for double shear in accordance with NASM 1312-13 (Aerospace Industries Association, February 1, 2003, incorporated herein by reference). The double-section test assesses the applicability of this combination of the chemical composition of the alloy and its thermomechanical processing to produce high-strength fastening material. The first set of round bars was tested in a cold drawn state, and the second set of round bars was tested after aging at 850 ° F for 1 hour and cooling in air to ambient temperature (850/1 / AC). The double shear strength test results are presented in Table 6 along with the average tensile strength, yield strength, and elongation. For comparison purposes, the minimum prescribed values for these mechanical properties of Ti-6Al-4V alloy fastener blanks are also presented in Table 6.

[0077] Cold drawn and aged alloys exhibited mechanical properties exceeding the minimum prescribed values for the Ti-6Al-4V alloy used in fastener blanks. In this regard, the methods described herein may provide a more effective alternative to the production of Ti-6Al-4V alloy products using OPCS processing.

[0078] Cold forming and aging of α + β-titanium alloys containing, in weight percent, from 2.90 to 5.00 aluminum, from 2.00 to 3.00 vanadium, from 0.40 to 2.00 iron , from 0.10 to 0.30 oxygen and titanium, in accordance with the various embodiments described herein, produce alloy products having mechanical properties that exceed the minimum prescribed mechanical properties of Ti-6Al-4V alloys for various applications, including, for example, Typical aerospace and fastener applications. As mentioned above, Ti-6Al-4V alloys require OTPS processing to achieve the required strength required for critical applications, such as, for example, aerospace applications. In this regard, the high strength of Ti-6Al-4V alloys is limited by the size of the products, which is due to the physical properties inherent in the material and the requirement for quick hardening during processing of OPCS. In contrast, high-strength articles of α + β-titanium alloys subjected to cold forming and aging, as described herein, are not limited to the dimensions of the article and its measurements. In addition, the cold-worked and aged high-strength α + β-titanium alloys, as described herein, do not experience large thermal and internal stresses or warping, which may be characteristic of thicker Ti-6Al-4V alloy products during processing OTRS.

[0079] This disclosure of the invention has been written with reference to various exemplary, illustrative and non-limiting embodiments. However, it will be understood by those skilled in the art that various substitutions, modifications, or combinations of any of the described embodiments (or parts thereof) can be made without departing from the scope of the invention. Thus, it is intended and understood that the present invention encompasses further embodiments not expressly set forth herein. Such embodiments may be obtained, for example, by combining, modifying, or reorganizing any of the described steps, components, elements, features, aspects, characteristics, limitations, and the like. in embodiments described herein. In this regard, the Applicant reserves the right to amend the claims in the course of paperwork to add features that are described differently here.

Claims (29)

1. The method of forming products from α + β-titanium alloy, including:
cold pressure treatment of α + β-titanium alloy at a temperature in the range from ambient temperature to 500 ° F; and
aging of an α + β-titanium alloy at a temperature in the range of 700 ° F to 1200 ° F after cold working without performing a solid solution treatment between cold working and aging, wherein the α + β-titanium alloy contains, in weight percent, 2.90 to 5.00 aluminum, from 2.00 to 3.00 vanadium, from 0.40 to 2.00 iron, from 0.10 to 0.30 oxygen, titanium and incidental impurities - the rest. 2. The method according to p. 1, in which, by cold forming and aging, a product is formed from an α + β-titanium alloy having a tensile strength in the range of 155 thousand psi. inch to 200 thousand pounds / sq. inch and elongation in the range from 8% to 20%, at ambient temperature. 3. The method according to p. 1, in which, by cold working and aging, an article is formed from an α + β-titanium alloy having a tensile strength in the range of 165 thousand psi. inch to 180 thousand pounds / sq. inch and elongation in the range from 8% to 17%, at ambient temperature. 4. The method according to p. 1, in which, by cold forming and aging, a product is formed from an α + β-titanium alloy having a yield strength in the range of 140 thousand psi. inch to 165 thousand pounds / sq. inch and elongation in the range from 8% to 20%, at ambient temperature. 5. The method according to p. 1, in which, by cold forming and aging, an article is formed from an α + β-titanium alloy having a yield strength in the range of 155 thousand psi. inch to 165 thousand pounds / sq. inch and elongation in the range from 8% to 15%, at ambient temperature. 6. The method according to claim 1, in which, by cold forming and aging, an α + β-titanium alloy product is formed having tensile strength, yield strength and elongation at ambient temperature, which are at least as large as the ultimate tensile strength, yield strength and elongation at ambient temperature for an otherwise identical product, consisting of a Ti-6Al-4V alloy, in the state after treatment for solid solution and aging. 7. The method according to p. 1, including cold pressure treatment of α + β-titanium alloy to a relative decrease in cross-sectional area from 20% to 60%. 8. The method according to p. 1, including cold pressure treatment of α + β-titanium alloy to a relative reduction in cross-sectional area from 20% to 40%. 9. The method according to claim 1, wherein the cold pressure treatment of the α + β-titanium alloy includes at least two deformation cycles, wherein each cycle includes cold pressure treatment of the α + β-titanium alloy to at least 10% relative reducing the cross-sectional area. 10. The method according to claim 1, wherein the cold pressure treatment of the α + β-titanium alloy comprises at least two deformation cycles, wherein each cycle includes cold pressure treatment of the α + β-titanium alloy to at least 20% relative reducing the cross-sectional area. 11. The method according to p. 1, including cold pressure treatment of α + β-titanium alloy at a temperature in the range from ambient temperature to 400 ° F. 12. The method according to p. 1, including cold pressure treatment of α + β-titanium alloy at ambient temperature. 13. The method according to p. 1, including the aging of α + β-titanium alloy at a temperature in the range from 800 ° F to 1150 ° F after cold working. 14. The method of claim 1, comprising aging an α + β-titanium alloy at a temperature in the range of 850 ° F to 1100 ° F after cold forming. 15. The method according to p. 1, including the aging of α + β-titanium alloy for up to 50 hours. 16. The method according to p. 15, including the aging of α + β-titanium alloy for from 0.5 to 10 hours. 17. The method according to claim 1, further comprising a hot pressure treatment of the α + β-titanium alloy at a temperature in the range of 300 ° F to 25 ° F below the temperature of the β-transformation of the α + β-titanium alloy, while the hot pressure treatment is performed before cold working. 18. The method according to p. 17, further comprising annealing the α + β-titanium alloy at a temperature in the range from 1200 ° F to 1500 ° F, wherein annealing is performed between the hot pressure treatment and the cold pressure treatment. 19. The method according to p. 17, including a hot pressure treatment of α + β-titanium alloy at a temperature in the range from 1500 ° F to 1775 ° F. 20. The method according to p. 1, wherein the α + β-titanium alloy consists of, in weight percent, from 2.90 to 5.00 aluminum, from 2.00 to 3.00 vanadium, from 0.40 to 2, 00 iron, from 0.10 to 0.30 oxygen and the rest is titanium and random impurities. 21. The method according to claim 1, wherein the α + β-titanium alloy consists of, in weight percent, from 3.50 to 4.50 aluminum, from 2.00 to 3.00 vanadium, from 1.00 to 2, 00 iron, from 0.10 to 0.30 oxygen and the rest is titanium and random impurities. 22. The method according to p. 1, wherein the α + β-titanium alloy consists of, in weight percent, from 3.70 to 4.30 aluminum, from 2.20 to 2.80 vanadium, from 1.20 to 1, 80 iron, from 0.22 to 0.28 oxygen and the rest is titanium and random impurities. 23. The method according to claim 1, in which the cold pressure treatment of the α + β-titanium alloy includes cold pressure treatment by performing at least one operation selected from the group consisting of rolling, forging, pressing, extrusion, pilgrim rolling, periodic rolling and drawing. 24. The method according to claim 1, wherein the cold pressure treatment of the α + β-titanium alloy includes cold drawing of the α + β-titanium alloy. 25. A product of α + β-titanium alloy, molded by the method according to claim 1. 26. The product according to p. 25, wherein the product is selected from the group consisting of a bar, rod, rod, tube, slab, plate and fixture. 27. The product according to p. 25, wherein the product has a diameter or thickness of more than 0.5 inches, tensile strength more than 165 thousand pounds / square. inch, yield strength of more than 155 thousand psi. inch and elongation greater than 12%. 28. The product according to claim 25, wherein the product has a diameter or thickness greater than 3.0 inches, tensile strength more than 165 thousand pounds / square. inch, yield strength of more than 155 thousand psi. inch and elongation greater than 12%. 29. The method according to p. 1, in which aging is carried out immediately after cold pressure treatment.

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