Titanium alloy

Abstract

To provide a titanium alloy which exhibits an advantageous combination of strength and ductility and in which a beta phase component does not substantially grow.SOLUTION: The alpha-beta titanium alloy comprises, in weight percent: an aluminum equivalency in the range of 2.0 to 10.0; a molybdenum equivalency in the range of 0 to 20.0; 0.3 to 5.0 cobalt; and titanium. In certain embodiments, the alpha-beta titanium alloys exhibit a cold work reduction ductility limit of at least 25%, yield strengths of at least 130KSI (896. 3MPa), and percent elongation of at least 10%. A method of forming an article comprising a cobalt-containing, alpha-beta titanium alloy comprises cold working the cobalt-containing, alpha-beta titanium alloy to a reduction in area of at least 25%. The cobalt-containing, alpha-beta titanium alloy does not exhibit substantial cracking during cold working.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to high strength alpha-beta titanium alloys. [Background technology]

[0002] Titanium alloys typically exhibit high strength-to-weight ratios, are corrosion resistant, and are creep resistant at relatively high temperatures. For these reasons, titanium alloys are used in aerospace, aviation, defense, marine, and automotive applications, such as landing gear components, engine frames, ballistic armor, ship hulls, and mechanical fasteners.

[0003] Reducing the weight of an aircraft or other powered vehicle results in fuel savings. Therefore, for example, in the aerospace industry, there is a strong desire to reduce the weight of aircraft. Titanium and titanium alloys are attractive materials for achieving weight reduction in aircraft applications because of their high strength-to-weight ratio. Most titanium alloy components used in aerospace applications are made of Ti-6Al-4V alloy (ASTM Grade 5; UNS R56400; AMS 4928, AMS 4911), which is an alpha-beta titanium alloy.

[0004] Ti-6Al-4V alloy is one of the most common titanium-based engineered materials, estimated to account for over 50% of the total titanium-based materials market. Ti-6Al-4V alloy is used in numerous applications that benefit from the alloy's advantageous combination of light weight, corrosion resistance, and high strength at low to moderate temperatures. For example, Ti-6Al-4V alloy is used to manufacture aircraft engine components, aircraft structural components, fasteners, high-performance automotive components, medical device components, sporting goods, components for marine applications, and components for chemical processing equipment.

[0005] Ductility is a property of any metallic material (i.e., metals and metal alloys). The cold formability of a metallic material is based, in part, on its ductility at or near room temperature and the material's ability to deform without cracking. High-strength alpha-beta titanium alloys, such as Ti-6Al-4V alloy, typically have poor cold formability at or near room temperature. This limits their amenability to low-temperature processing, such as cold rolling, because these alloys are prone to cracking and fracture when worked at low temperatures. Therefore, due to their limited cold formability at or near room temperature, alpha-beta titanium alloys are typically processed by techniques that involve extensive hot working.

[0006] Titanium alloys that exhibit ductility at room temperature also generally exhibit relatively low strength. As a result, high-strength alloys are typically more costly and have poor thickness control due to cutting resistance. This problem is due to the distortion of the hexagonal close-packed (HCP) crystal structure in these higher-strength beta alloys at temperatures below a few hundred degrees Celsius.

[0007] The HCP crystal structure is common in many engineering materials, such as magnesium, titanium, zirconium, and cobalt alloys. While the HCP crystal structure has an ABABAB stacking sequence, other metal alloys, such as stainless steel, brass, nickel, and aluminum alloys, typically have a face-centered cubic (FCC) crystal structure with an ABCABCABC stacking sequence. As a result of this difference in stacking sequence, HCP metals and alloys have a significantly smaller number of mathematically possible independent slip systems compared to FCC materials. Many independent slip systems in HCP metals and alloys require significantly higher stresses to activate, and these "high-resistance" deformation modes are activated only very rarely. This effect is temperature-sensitive, resulting in significantly lower ductility of titanium alloys below temperatures of a few hundred degrees Celsius.

[0008] In combination with the slip systems present in HCP materials, many twist systems are also possible in unalloyed HCP materials. The combination of slip and twist systems in titanium allows for sufficiently independent modes of deformation that "commercially pure" (CP) titanium can be cold worked at temperatures near room temperature (i.e., in the range of approximately -100°C to +200°C).

[0009] The alloying effect of titanium and other HCP materials and alloys not only increases the asymmetry or difficulty of "high-tolerance" slip modes, but also tends to suppress the activation of torsion systems. This results in a macroscopic loss of cold workability in alloys such as Ti-6Al-4V and Ti-6Al-2-Sn-4Zr-2Mo-0.1Si. Ti-6Al-4V and Ti-6Al-2-Sn-4Zr-2Mo-0.1Si exhibit relatively high strength due to their high alpha phase concentration and high levels of alloying elements. Aluminum, in particular, is known to increase the strength of titanium alloys at both room and high temperatures. However, aluminum is also known to adversely affect room-temperature workability.

[0010] Generally, alloys that exhibit cold deformation capability can be manufactured more efficiently, both in terms of energy consumption and the amount of waste generated during processing, so it is usually advantageous to formulate alloys that can be processed at relatively low temperatures.

[0011] Several known titanium alloys contain high concentrations of beta-phase stabilizing alloying additions to impart improved room-temperature processability. An example of such an alloy is the beta-C titanium alloy (Ti-3Al-8V-6Cr-4Mo-4Zr; UNS R58649), available in one form as ATI® 38-644™ beta titanium alloy from Allegheny Technologies Incorporated, Pittsburgh, Pennsylvania, USA. This alloy and similarly formulated alloys derive their advantageous cold processability from the reduction and / or elimination of alpha phase from their microstructure. Typically, these alloys are capable of precipitating the alpha phase during low-temperature aging.

[0012] Despite these advantageous cold-working capabilities, beta titanium alloys generally suffer from two drawbacks: expensive alloying additives and poor high-temperature creep strength. The poor high-temperature creep strength is a result of the high concentration of beta phase that these alloys exhibit at high temperatures, such as 500°C. The beta phase is less resistant to creep due to its body-centered cubic structure, which provides many deformation mechanisms. Machining beta titanium alloys is also known to be difficult due to the alloy's relatively low elastic modulus, which allows for greater springback. As a result of these shortcomings, the use of beta titanium alloys has been limited.

[0013] If existing titanium alloys were more resistant to cracking during cold processing, lower-cost titanium products would be possible. Because alpha-beta titanium alloys dominate all manufactured alloyed titanium, maintaining this type of alloy would further reduce the cost per amount of scale. Therefore, high-strength, cold-formable alpha-beta titanium alloys are of interest for investigation. Several alloys within this alloy class have been recently developed. For example, in the last 15 years, Ti-4Al-2.5V alloy (UNS R54250), Ti-4.5Al-3V-2Mo-2Fe alloy, Ti-5Al-4V-0.7Mo-0.5Fe alloy, and Ti-3Al-5Mo-5V-3Cr-0.4Fe alloy have been developed. Many of these alloys feature expensive alloying additions, such as V and / or Mo.

[0014] The Ti-6Al-4V alpha-beta titanium alloy is the standard titanium alloy used in the aerospace industry, and it accounts for the majority of all titanium alloys by tonnage. In the aerospace industry, this alloy is known to be unable to be cold worked at room temperature. The lower oxygen content grades of Ti-6Al-4V alloy, designated as Ti-6Al-4V ELI ("Extra Low Interstitial Elements") alloy (UNS 56401), typically exhibit improved room temperature ductility, toughness, and formability compared to higher oxygen content grades. However, the strength of Ti-6Al-4V alloy decreases significantly as the oxygen content decreases. Those skilled in the art would expect the addition of oxygen to adversely affect cold forming ability in Ti-6Al-4V alloy, and to be beneficial to strength.

[0015] However, despite its higher oxygen content than standard grades of Ti-6Al-4V alloy, Ti-4Al-2.5V-1.5Fe-0.25O alloy (also known as Ti-4Al-2.5V alloy) is known to have superior formability at or near room temperature compared to Ti-6Al-4V alloy. Ti-4Al-2.5V-1.5Fe-0.25O alloy is commercially available as ATI 425® titanium alloy from Allegheny Technologies Incorporated. The near-room temperature formability advantages of ATI 425® alloy are discussed in U.S. Patent Nos. 8,048,240, 8,597,442, and 8,597,443, and U.S. Patent Application No. 2014-0060138A1, each of which is incorporated herein by reference in its entirety.

[0016] Another cold-formable, high-strength alpha-beta titanium alloy is Ti-4.5Al-3V-2Mo-2Fe, also known as SP-700. Unlike Ti-4Al-2.5V, SP-700 contains higher-cost alloying elements. Like Ti-4Al-2.5V, SP-700 has reduced creep resistance compared to Ti-6Al-4V due to its increased beta phase content.

[0017] The Ti-3Al-5Mo-5V-3Cr alloy also exhibits good room-temperature formability. However, this alloy contains a significant amount of beta phase at room temperature, which results in poor creep resistance. Furthermore, it contains significant levels of expensive alloying elements such as molybdenum and chromium.

[0018] It is generally understood that cobalt does not significantly affect the mechanical strength and ductility of most titanium alloys compared to other alloying additions. While cobalt additions can increase the strength of binary and ternary titanium alloys, it has been shown that cobalt additions typically result in a significant decrease in ductility compared to the addition of iron, molybdenum, or vanadium (typical alloying additions). While the addition of cobalt to Ti-6Al-4V alloy can improve strength and ductility, it has also been shown that Ti3X-type interstitial precipitates can form during aging, which can adversely affect other mechanical properties.

[0019] It would be advantageous to provide a titanium alloy that contains relatively small amounts of expensive alloying additions, exhibits an advantageous combination of strength and ductility, and is substantially free of beta phase growth. Summary of the Invention

[0020] According to a non-limiting embodiment of the present disclosure, an alpha-beta titanium alloy contains, in weight percent, an aluminum equivalent ranging from 2.0 to 10.0; a molybdenum equivalent ranging from 0 to 20.0; cobalt ranging from 0.3 to 5.0; titanium; and incidental impurities. As defined herein, aluminum equivalent is the weight percent equivalent of aluminum, calculated according to the following formula, in which the content of each alpha phase stabilizing element is in weight percent: [Al] eq =[Al]+1 / 3[Sn]+1 / 6[Zr+Hf]+10[O+2N+C]+[Ga]+[Ge].

[0021] As defined herein, molybdenum equivalent is the equivalent weight percent of molybdenum, calculated by the following formula, where the content of each beta-phase stabilizing element is in weight percent: [Mo] eq =[Mo]+2 / 3[V]+3[Mn+Fe+Ni+Cr+Cu+Be]+1 / 3[Ta+Nb+W].

[0022] According to another non-limiting embodiment of the present disclosure, the alpha-beta titanium alloy contains, in weight percent, 2.0 to 7.0 aluminum; a molybdenum equivalent ranging from 2.0 to 5.0; cobalt from 0.3 to 4.0; oxygen up to 0.5; nitrogen up to 0.25; carbon up to 0.3; incidental impurities up to 0.4; and titanium. The molybdenum equivalent is given by the formula: [Mo] eq =[Mo]+2 / 3[V]+3[Mn+Fe+Ni+Cr+Cu+Be]+1 / 3[Ta+Nb+W].

[0023] An additional non-limiting aspect of the present disclosure relates to a method for forming an article from an alpha-beta titanium alloy. In a non-limiting embodiment, the method for forming an alpha-beta titanium alloy comprises cold working a metal part to a reduction in area of ​​at least 25%, wherein the metal part does not exhibit significant cracking during or after the cold working. In a non-limiting embodiment, the metal part comprises an alpha-beta titanium alloy containing, in weight percent, an aluminum equivalent ranging from 2.0 to 10.0; a molybdenum equivalent ranging from 0 to 20.0; cobalt ranging from 0.3 to 5.0; titanium; and incidental impurities. The aluminum equivalent is the equivalent weight percent of aluminum, calculated according to the following formula, wherein the content of each alpha phase stabilizing element is in weight percent: [Al] eq =[Al]+1 / 3[Sn]+1 / 6[Zr+Hf]+10[O+2N+C]+[Ga]+[Ge].

[0024] Molybdenum equivalent is the equivalent weight percent of molybdenum, calculated by the following formula, where the content of each beta-phase stabilizing element is in weight percent: [Mo] eq =[Mo]+2 / 3[V]+3[Mn+Fe+Ni+Cr+Cu+Be]+1 / 3[Ta+Nb+W].

[0025] Another non-limiting aspect of the present disclosure relates to a method for forming an article from an alpha-beta titanium alloy. In a non-limiting embodiment, forming the alpha-beta titanium alloy includes providing an alpha-beta titanium alloy containing, in weight percent, 2.0-7.0 aluminum; molybdenum equivalent ranging from 2.0-5.0; cobalt 0.3-4.0; oxygen up to 0.5; nitrogen up to 0.25; carbon up to 0.3; incidental impurities up to 0.2; and titanium. The method further includes producing a cold-worked structure, where the material is capable of undergoing a cold reduction of 25% or more in cross section.

[0026] It is understood that the invention disclosed and described herein is not limited to the embodiments summarized in this Summary of the Invention.

[0027] The various features and characteristics of the non-limiting and non-exhaustive embodiments disclosed and described herein can be better understood by reference to the accompanying drawings. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a flow diagram of a non-limiting embodiment of the method of the present disclosure. [Figure 2] 1 is a flow diagram of another non-limiting embodiment of the method of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0029] The reader will understand the above specification and more by reviewing the following detailed description of non-limiting and non-exhaustive embodiments of the present disclosure.

[0030] Various embodiments are described and illustrated herein to provide a complete understanding of the structure, function, operation, manufacture, and use of the disclosed methods and products. It is understood that the various embodiments disclosed and illustrated herein are non-limiting and non-exhaustive. Accordingly, the present invention is not limited by the description of the various non-limiting and non-exhaustive embodiments disclosed herein. Rather, the present invention is defined solely by the claims. Features and characteristics illustrated and / or described in connection with various embodiments may be combined with features and characteristics of other embodiments. Such modifications and variations are intended to be encompassed within the scope of the present specification. Accordingly, the claims may be amended to recite any feature or characteristic explicitly or implicitly described in or supported by the present specification. Furthermore, applicants reserve the right to amend the claims to affirmatively exclude features or characteristics that may exist in the prior art. Accordingly, all such amendments will comply with the requirements of 35 U.S.C. §112, first paragraph, and 35 U.S.C. §132(a). The various embodiments disclosed and described herein may comprise, consist of, or consist essentially of the features and characteristics variously described herein.

[0031] All percentages and ratios given for alloy compositions are by total weight of that particular alloy composition unless otherwise indicated.

[0032] All patents, publications, or other disclosure materials that are incorporated by reference herein in whole or in part are incorporated herein only to the extent that the incorporated material does not contradict existing definitions, descriptions, or other disclosure materials set forth in the present disclosure. As such and to the extent necessary, the disclosure set forth herein supersedes all conflicting material incorporated by reference herein. All material, or portions thereof, that is incorporated herein by reference but that contradicts existing definitions, descriptions, or other disclosure materials set forth herein is incorporated only to the extent that there is no contradiction between the incorporated material and the existing disclosure materials.

[0033] In this specification, unless otherwise indicated, all numerical parameters should be understood as being prefaced and modified by the term "about," in all instances, given the variability inherent in the measuring techniques employed to determine the numerical value of the parameter. At the very least, and without any intention to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter set forth herein should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0034] Similarly, all numerical ranges recited herein are intended to include all subranges of the same numerical precision subsumed within the recited range. For example, a range of "1.0 to 10.0" is intended to include all subranges between (and including) the recited minimum value of 1.0 and the recited maximum value of 10.0, i.e., all subranges having a minimum value of 1.0 or greater and a maximum value of 10.0 or less, such as 2.4 to 7.6. Every maximum numerical limitation recited herein is intended to include all subsumed lower numerical limitations, and every minimum numerical limitation recited herein is intended to include all subsumed higher numerical limitations. Accordingly, applicants reserve the right to amend this specification, including the claims, to expressly recite all subranges subsumed within the ranges expressly recited herein. All such ranges are intended to be implicitly stated herein such that an amendment to expressly recite all such subranges would satisfy the requirements of 35 U.S.C. §112, first paragraph, and 35 U.S.C. §132(a).

[0035] As used herein, the grammatical articles "one," "a," "an," and "the" are intended to include "at least one" or "one or more," unless otherwise indicated. As such, articles are used herein to refer to one or more (i.e., "at least one") of the grammatical object of the article. For example, "a component" means one or more components, and thus, in some cases, more than one component is contemplated and may be employed or used in the practice of the described embodiments. Furthermore, unless the context of usage requires otherwise, the use of a singular noun includes the plural and the use of a plural noun includes the singular.

[0036] As used herein, the term "billet" refers to a solid, semi-finished product, typically having a circular or square cross section, that has been hot worked, typically by forging, rolling, or extrusion. This definition is consistent with the definition of "billet" in, for example, ASM Materials Engineering Dictionary, J.R.Davis, ed., ASM International (1992), p. 40.

[0037] As used herein, the term "bar" refers to a solid product that is forged, rolled, or extruded from a billet into a form that is generally symmetrical, usually having a round, hexagonal, octagonal, square, or rectangular cross-section, with sharp or rounded ends, and a length that is greater than its cross-sectional dimensions. This definition is consistent with the definition of "bar" in, for example, the ASM Materials Engineering Dictionary, J.R.Davis, ed., ASM International (1992), p. 32. As used herein, the term "bar" may refer to the above-described forms, although it is recognized that the form may not have a symmetrical cross-section, such as the asymmetrical cross-section of a hand-rolled bar.

[0038] As used herein, the phrase "cold working" refers to working a metallic (i.e., metal or metal alloy) article below a temperature at which the flow stress of the material is significantly reduced. Examples of cold working include treating a metallic article at such temperatures using one or more techniques selected from rolling, forging, extrusion, pilger rolling, orbital rolling, drawing, flow turning, liquid compression molding, gas compression molding, hydroforming, flow forming, bulge forming, roll forming, stamping, fine blanking, die pressing, deep drawing, coining, spinning, swaging, impact extrusion, explosive forming, rubber molding, reverse extrusion, piercing, stretch forming, press bending, electromagnetic forming, and cold heading. As used herein in connection with the present invention, "cold working," "cold worked," "cold formed," and similar terms, as well as "cold" when used in connection with specific working or forming techniques, refer to the property of working or processing at temperatures below about 1250°F (677°C), as the case may be. In some embodiments, such working occurs at a temperature of about 1000°F (538°C) or less. In some other embodiments, cold working occurs at a temperature of about 575°F (300°C) or less. The terms "working" and "forming" are generally used interchangeably herein, as are the terms "workable" and "formable" and similar terms.

[0039] As used herein, the phrase "ductility limit" refers to the limit or maximum amount of reduction or plastic deformation that a metallic material can withstand without fracture or cracking. This definition is consistent with the definition of "ductility limit" in, for example, ASM Materials Engineering Dictionary, J.R.Davis, ed., ASM International (1992), p. 131. As used herein, the term "reduction ductility limit" refers to the amount or degree of reduction that a metallic material can withstand before cracking or fracture occurs. This refers to:

[0040] References herein to an alpha-beta titanium alloy "comprising" a particular composition are intended to encompass alloys "consisting essentially of" or "consisting of" the stated composition. It will be understood that alpha-beta titanium alloy compositions described herein that "comprise," "consist," or "consist essentially of" a particular composition may also include unavoidable impurities.

[0041] A non-limiting aspect of the present disclosure relates to cobalt-containing alpha-beta titanium alloys that exhibit certain cold deformation characteristics superior to those of Ti-6AI-4V alloy, without the need to impart additional beta phase or further restrict the oxygen content compared to Ti-6AI-4V alloy. The ductility limit of the disclosed alloys is significantly improved compared to Ti-6AI-4V alloy.

[0042] Contrary to the current perception that adding oxygen to titanium alloys reduces the alloy's formability, the cobalt-containing alpha-beta titanium alloys disclosed herein have greater formability than Ti-6Al-4V alloy, while containing up to 66% more oxygen than Ti-6Al-4V alloy. The composition ranges of the cobalt-containing alpha-beta titanium embodiments disclosed herein allow for greater flexibility in alloy utilization without the significant additional costs associated with alloying additions. While various alloy embodiments according to the present disclosure may be more expensive than Ti-4Al-2.5V alloy in terms of starting material costs, the cost of alloying additions for the cobalt-containing alpha-beta titanium alloys disclosed herein can be lower than certain other cold-formable alpha-beta titanium alloys.

[0043] The addition of cobalt to the alpha-beta titanium alloys disclosed herein has been found to improve the ductility of the alloys when the alloys also contain low levels of aluminum. Furthermore, the addition of cobalt to alpha-beta titanium alloys according to the present disclosure has been found to increase the strength of the alloys.

[0044] According to a non-limiting embodiment of the present disclosure, the alpha-beta titanium alloy contains, in weight percent, an aluminum equivalent ranging from 2.0 to 10.0; a molybdenum equivalent ranging from 0 to 20.0; cobalt ranging from 0.3 to 5.0; titanium; and incidental impurities.

[0045] In another non-limiting embodiment, the alpha-beta titanium alloy contains, in weight percent, an aluminum equivalent ranging from 2.0 to 10.0; a molybdenum equivalent ranging from 0 to 10.0; cobalt ranging from 0.3 to 5.0; and titanium. In yet another non-limiting embodiment, the alpha-beta titanium alloy contains, in weight percent, an aluminum equivalent ranging from 1.0 to 6.0; a molybdenum equivalent ranging from 0 to 10.0; cobalt ranging from 0.3 to 5.0; and titanium. For each embodiment disclosed herein, the aluminum equivalent is in weight percent equivalent of aluminum, calculated according to the following formula, wherein the content of each alpha phase stabilizing element is in weight percent: [Al] eq =[Al]+1 / 3[Sn]+1 / 6[Zr+Hf]+10[O+2N+C]+[Ga]+[Ge].

[0046] Although cobalt is known to be a beta-phase stabilizer for titanium, for all embodiments disclosed herein, the molybdenum equivalent is in weight percent equivalent of molybdenum and is calculated herein by the following formula, in which the content of each beta-phase stabilizer element is in weight percent: [Mo] eq =[Mo]+2 / 3[V]+3[Mn+Fe+Ni+Cr+Cu+Be]+1 / 3[Ta+Nb+W].

[0047] In certain non-limiting embodiments of the present disclosure, the cobalt-containing alpha-beta titanium alloys disclosed herein comprise a total of greater than 0 wt.% and up to 0.3 wt.% of one or more refinement additions. The one or more refinement additions may be any refinement addition known to those skilled in the art, such as, but not necessarily limited to, cerium, praseodymium, neodymium, samarium, gadolinium, holmium, erbium, thulium, yttrium, scandium, beryllium, and boron.

[0048] In a further non-limiting embodiment, any cobalt-containing alpha-beta titanium alloy disclosed herein may further comprise a total of greater than 0 wt.% and up to 0.5 wt.% of one or more corrosion-inhibiting metal additives. The corrosion-inhibiting additive may be any one or more corrosion-inhibiting additives known for use in alpha-beta titanium alloys. Such additives include, but are not limited to, gold, silver, palladium, platinum, nickel, and iridium.

[0049] In further non-limiting embodiments, any cobalt-containing alpha-beta titanium alloy disclosed herein may include, in weight percent, one or more of: tin from greater than 0 up to 6.0; silicon from greater than 0 up to 0.6; and zirconium from greater than 0 up to 10. The addition of these elements within these concentration ranges is not believed to affect the ratio of alpha to beta phase concentrations in the alloy.

[0050] In one non-limiting embodiment of the alpha-beta titanium alloy according to the present disclosure, the alpha-beta titanium alloy exhibits a yield strength of at least 130 KSI (896.3 MPa) and an elongation of at least 10%. In another non-limiting embodiment, the alpha-beta titanium alloy exhibits a yield strength of at least 150 KSI (1034 MPa) and an elongation of at least 16%.

[0051] In certain non-limiting embodiments of the alpha-beta titanium alloy according to the present disclosure, the alpha-beta titanium alloy exhibits a cold work reduction ductility limit of at least 20%. In other non-limiting embodiments, the alpha-beta titanium alloy exhibits a cold work reduction ductility limit of at least 25%, or at least 35%.

[0052] In some non-limiting embodiments of the alpha-beta titanium alloy according to the present disclosure, the alpha-beta titanium alloy further comprises aluminum. In non-limiting embodiments, the alpha-beta titanium alloy contains, in weight percent, 2.0 to 7.0 aluminum; a molybdenum equivalent ranging from 2.0 to 5.0; cobalt from 0.3 to 4.0; oxygen up to 0.5; nitrogen up to 0.25; carbon up to 0.3; incidental impurities up to 0.2; and titanium. The molybdenum equivalent is determined as described herein. In some non-limiting embodiments, the alpha-beta titanium alloys herein containing aluminum may further include, in weight percent, one or more of: tin from greater than 0 to 6; silicon from greater than 0 to 0.6; zirconium from greater than 0 to 10; palladium from greater than 0 to 0.3; and boron from greater than 0 to 0.5.

[0053] In certain non-limiting embodiments of alpha-beta titanium alloys according to the present disclosure containing aluminum, the alloy may further comprise a total of greater than 0% and up to 0.3% by weight of one or more refinement additions, such as, for example, any of the following refinement additions: cerium, praseodymium, neodymium, samarium, gadolinium, holmium, erbium, thulium, yttrium, scandium, beryllium, and boron.

[0054] Certain non-limiting examples of alpha-beta titanium alloys according to the present disclosure containing aluminum include: In embodiments, the alloy may further include one or more corrosion-resistant additives known to those skilled in the art, such as, but not limited to, gold, silver, palladium, platinum, nickel, and iridium, in a total amount of greater than 0% and up to 0.5% by weight.

[0055] One non-limiting embodiment of the alpha-beta titanium alloys disclosed herein containing cobalt and aluminum exhibits a yield strength of at least 130 KSI (896 MPa) and an elongation of at least 10%. Another non-limiting embodiment of the alpha-beta titanium alloys disclosed herein containing cobalt and aluminum exhibits a yield strength of at least 150 KSI (1034 MPa) and an elongation of at least 16%.

[0056] One non-limiting embodiment of the alpha-beta titanium alloys disclosed herein containing cobalt and aluminum exhibits a cold work reduction ductility limit of at least 25%. Another non-limiting embodiment of the alpha-beta titanium alloys disclosed herein containing cobalt and aluminum exhibits a cold work reduction ductility limit of at least 35%.

[0057] Referring to FIG. 1 , another aspect of the present disclosure relates to a method 100 of forming an article from a metal shaped article comprising an alpha-beta titanium alloy according to the present disclosure. The method 100 includes cold working 102 the metal shaped article to a reduction in area of ​​at least 25%. The metal shaped article comprises any of the alpha-beta titanium alloys disclosed herein. During cold working 102, according to certain aspects of the present disclosure, the metal shaped article does not exhibit gross cracks. The term "gross cracks" is defined herein as the formation of cracks greater than about 0.5 inches. In another non-limiting embodiment of a method of forming an article according to the present disclosure, a metal shaped article comprising an alpha-beta titanium alloy disclosed herein is cold worked 102 to a reduction in area of ​​at least 35%. During cold working 102, the metal shaped article does not exhibit gross cracks.

[0058] In certain embodiments, cold working 102 the metal forming article includes cold rolling the metal forming article.

[0059] In a non-limiting embodiment of a method according to the present disclosure, the metal shaped article is cold worked 102 at a temperature less than 1250°F (676.7°C). In another non-limiting embodiment of a method according to the present disclosure, the metal shaped article is cold worked 102 at a temperature less than 392°F (200°C). In another non-limiting embodiment of a method according to the present disclosure, the metal shaped article is cold worked 102 at a temperature of 575°F (300°C) or less. In yet another non-limiting embodiment of a method according to the present disclosure, the metal shaped article is cold worked 102 at a temperature ranging from -100°C to 200°C.

[0060] In a non-limiting embodiment of a method according to the present disclosure, the metal part is cold worked 102 to a reduction of at least 25% or at least 35%, with intermediate anneals (not shown) between them. The metal part may be annealed between intermediate cold working steps at a temperature below the beta-transus temperature of the alloy to relieve internal stresses and minimize the chance of edge cracking. In a non-limiting embodiment, the annealing steps (not shown) between the cold working steps 102 are performed at a temperature below the T β -20℃~T β The alloys of the present disclosure may further comprise annealing the metal article at a temperature in the range of -300°C for 5 minutes to 2 hours. β The T of any particular alloy of the present disclosure is typically between 900°C and 1100°C. β can be determined by one of ordinary skill in the art using conventional techniques without undue experimentation.

[0061] After cold working 102 the metal part, in certain non-limiting embodiments of the method, the metal part may be factory annealed (not shown) to obtain the desired strength and ductility and alpha-beta microstructure of the alloy. In non-limiting embodiments, the factory anneal involves heating the metal part to a temperature in the range of 600°C to 930°C and holding for 5 minutes to 2 hours. may be included.

[0062] The metal shaped articles processed by various embodiments of the methods disclosed herein may be selected from any factory or semi-finished factory product, such as ingots, billets, blooms, bars, beams, slabs, rods, wire, plates, sheets, extrusions, and castings.

[0063] Non-limiting embodiments of the methods disclosed herein further include hot working (not shown) the metal forming article prior to cold working 102 the metal forming article. Those skilled in the art will recognize that hot working includes plastically deforming the metal forming article at a temperature above the recrystallization temperature of the alloy comprising the metal forming article. In certain non-limiting embodiments, the metal forming article may be hot worked at a temperature in the beta phase field of an alpha-beta titanium alloy ... β The metal part may be heated to a temperature of +30°C and then hot worked. In one non-limiting embodiment, the metal part may be hot worked to a rolling reduction of at least 20% at a temperature in the beta phase field of the titanium alloy. In one non-limiting embodiment, after hot working the metal part in the beta phase field, the metal part may be cooled to ambient temperature at a rate at least comparable to air cooling.

[0064] After hot working in the beta phase field, in various non-limiting embodiments of the disclosed method, the metal part may be further hot worked at a temperature in the alpha-beta phase field. Hot working in the alpha-beta phase field may include reheating the metal part to a temperature in the alpha-beta phase field. Alternatively, after working the metal part in the beta phase field, the metal part may be cooled to a temperature in the alpha-beta phase field and then further hot worked. In non-limiting embodiments, the alpha-beta phase field hot working temperature is T β -300℃~T βIn a non-limiting embodiment, the metal part is hot worked in the alpha-beta phase field to a rolling reduction of at least 30%. In a non-limiting embodiment, after hot working in the alpha-beta phase field, the metal part may be cooled to ambient temperature at a rate at least comparable to air cooling. After cooling, in a non-limiting embodiment, the metal part is cooled to T β -20℃~T β It may be annealed at a temperature in the range of -300°C for 5 minutes to 2 hours.

[0065] Referring to Figure 2, another non-limiting embodiment of the present disclosure relates to a method 200 of forming an article from an alpha-beta titanium alloy, the method including providing 202 an alpha-beta titanium alloy containing, in weight percent, aluminum in the range of 2.0 to 7.0; molybdenum equivalent in the range of 2.0 to 5.0; cobalt in the range of 0.3 to 4.0; oxygen up to 0.5; nitrogen up to 0.25; carbon up to 0.3; incidental impurities up to 0.2; and titanium. As such, the alloy is referred to as a cobalt-containing aluminum-containing alpha-beta titanium alloy. The alloy is cold worked 204 to a reduction in area of ​​at least 25%. The cobalt-containing aluminum-containing alpha-beta titanium alloy does not exhibit significant cracking during cold working 204.

[0066] The molybdenum equivalent of the cobalt-containing aluminum-containing alpha-beta titanium alloy is given by the following formula, where the beta phase stabilizing elements are listed in weight percent: [Mo] eq =[Mo]+2 / 3[V]+3[Mn+Fe+Ni+Cr+Cu+Be]+1 / 3[Ta+Nb+W].

[0067] In another non-limiting method embodiment of the present disclosure, the cobalt-containing aluminum-containing alpha-beta titanium alloy is cold worked to a reduction in area of ​​at least 35%.

[0068] In a non-limiting embodiment, a cobalt-containing aluminum-containing alpha-beta titanate is Cold working 204 of the titanium alloy to a reduction of at least 25%, or at least 35%, may be performed in one or more cold rolling steps. The cobalt-containing aluminum-containing alpha-beta titanium alloy may be annealed (not shown) between multiple cold working steps 204 at a temperature below the beta-transus temperature to relieve internal stresses and minimize the chance of edge cracking. In a non-limiting embodiment, the annealing step between cold working steps is performed at a temperature below the beta-transus temperature. β -20℃~T β The present invention may also include annealing the cobalt-containing aluminum-containing alpha-beta titanium alloy at a temperature in the range of -300°C for 5 minutes to 2 hours. β The T of any particular alloy of the present disclosure is typically between 900°C and 1200°C. β can be determined by one of ordinary skill in the art without undue experimentation.

[0069] After cold working 204, in a non-limiting embodiment, the cobalt-containing aluminum-containing alpha-beta titanium alloy may be factory annealed (not shown) to achieve the desired strength and ductility. In a non-limiting embodiment, the factory anneal may include heating the cobalt-containing aluminum-containing alpha-beta titanium alloy to a temperature in the range of 600°C to 930°C and holding for a period of 5 minutes to 2 hours.

[0070] In certain embodiments, the cold working 204 of the cobalt-containing aluminum-containing alpha-beta titanium alloy disclosed herein comprises cold rolling.

[0071] In a non-limiting embodiment, the cobalt-containing aluminum-bearing alpha-beta titanium alloy disclosed herein is cold worked 204 at a temperature less than 1250°F (676.7°C). In another non-limiting embodiment of the method according to the present disclosure, the cobalt-containing aluminum-bearing alpha-beta titanium alloy disclosed herein is cold worked 204 at a temperature of 575°F (300°C) or less. In another non-limiting embodiment, the cobalt-containing aluminum-bearing alpha-beta titanium alloy disclosed herein is cold worked 204 at a temperature less than 392°F (200°C). In yet another non-limiting embodiment, the cobalt-containing aluminum-bearing alpha-beta titanium alloy disclosed herein is cold worked 204 at a temperature ranging from -100°C to 200°C.

[0072] Prior to the cold working step 204, the cobalt-containing aluminum-containing alpha-beta titanium alloy disclosed herein may be a factory produced or semi-finished factory produced product in a form selected from one of an ingot, a billet, a bloom, a beam, a slab, a rod, a bar, a tube, a wire, a plate, a sheet, an extrusion, and a casting.

[0073] Also prior to the cold working step, the cobalt-containing aluminum-bearing alpha-beta titanium alloy disclosed herein may be hot worked (not shown). The hot working treatments disclosed herein above for the metal shaped article are equally applicable to the cobalt-containing aluminum-bearing alpha-beta titanium alloy disclosed herein.

[0074] The cold formability of the cobalt-containing alpha-beta titanium alloys disclosed herein, which contain higher oxygen levels than those found in, for example, Ti-6Al-4V alloy, is counterintuitive. For example, Grade 4 CP (commercially available), which contains relatively high levels of oxygen, up to 0.4 wt. %. Pure titanium is known to have lower formability than other CP grades. Grade 4 Although the CP alloy has higher strength than Grade 1, 2, or 3CP, it exhibits lower strength than the alloy embodiments of the present disclosure.

[0075] Cold working techniques that may be used with the cobalt-containing alpha-beta titanium alloys disclosed herein include, for example, but are not limited to, cold rolling, cold drawing, cold extrusion, swing / pilger rolling, cold swaging, spinning, and flow turning. As is known in the art, cold rolling is typically used to produce bars, sheets, plates, etc. The process involves passing a previously hot-rolled article, such as a sheet or strip, through a series of rolls, often multiple times, until the desired dimensions are achieved. It is believed that, depending on the starting structure after hot (alpha-beta) rolling and annealing, a reduction in area (RA) of at least 35-40% may be obtained by cold rolling cobalt-bearing alpha-beta titanium alloys before any annealing is required prior to additional cold rolling. Subsequent cold reductions of at least 20-60%, or at least 25%, or at least 35% are believed possible, depending on the product width and rolling mill configuration.

[0076] Based on the inventors' observations, cold rolling of bars, rods, and wires in various bar-type mills, such as Koch-type mills, can also be performed on the cobalt-containing alpha-beta titanium alloys disclosed herein. Additional non-limiting examples of cold working techniques that can be used to form articles from the cobalt-containing alpha-beta titanium alloys disclosed herein include pilger rolling (oscillating) of extruded tubular hollow bodies for the production of seamless pipes, tubes, and ducts. Based on the observed properties of the cobalt-containing alpha-beta titanium alloys disclosed herein, it is believed that greater reductions of area (RA) can be obtained with compression-type forming than with flat rolling. Drawing of rods, wires, bars, and tubular hollow bodies can also be performed. A particularly attractive application of the cobalt-containing alpha-beta titanium alloys disclosed herein is drawing or pilger rolling into tubular hollow bodies for the production of seamless tubes, which is particularly difficult to achieve with Ti-6Al-4V alloy. The cobalt-containing alpha-beta titanium alloys disclosed herein may be used to perform flow forming (also known in the art as iron spinning) to produce axisymmetric hollow articles such as cones, cylinders, aircraft ducts, nozzles, and other "flow-related" type parts. Various liquid- or gas-type compression and expansion-type forming processes, such as hydroforming or bulging, may also be used. Continuous-type stock roll forming may be performed to form structural variations of the common structural members "angle iron" or "unistrut." Furthermore, based on the inventors' discoveries, processes typically associated with sheet metal processing, such as stamping, fine blanking, die pressing, deep drawing, and coining, may also be applied to the cobalt-containing alpha-beta titanium alloys disclosed herein.

[0077] In addition to the cold-forming techniques described above, it is believed that other "cold" techniques that may be used to form articles from the cobalt-containing alpha-beta titanium alloys disclosed herein include, but are not necessarily limited to, forging, extrusion, flow turning, hydroforming, bulge forming, roll forming, swaging, impact extrusion, explosive forming, rubber forming, reverse extrusion, piercing, spinning, stretch forming, press bending, electromagnetic forming, and cold heading. In light of the inventors' observations and conclusions, as well as the other details provided in this description of the invention, those skilled in the art will readily recognize additional cold-working / forming techniques that may be applied to the cobalt-containing alpha-beta titanium alloys disclosed herein, and will be able to readily apply such techniques to the alloys without undue experimentation. Accordingly, only certain examples of cold-working of the alloys are disclosed herein. By utilizing such cold-working and forming techniques, a variety of articles can be provided. Such articles include, but are not necessarily limited to, sheets, strips, foils, plates, bars, rods, wires, hollow tubular bodies, pipes, tubes, fabrics, meshes, structural members, cones, cylinders, ducts, pipes, nozzles, honeycomb structures, fasteners, rivets, and washers.

[0078] The unexpected cold workability of the cobalt-bearing alpha-beta titanium alloys disclosed herein results in finer surface finishes and reduces the need for surface treatments to remove the heavy surface scale and diffusion oxide layers that typically occur on the surface of lap-rolled sheets of Ti-6Al-4V alloy. Given the level of cold workability observed by the inventors, it is believed that the cobalt-bearing alpha-beta titanium alloys disclosed herein will exhibit similar characteristics to those of Ti-6Al-4V alloy. It is believed that it is possible to produce foil thickness products of coil length that have the required properties.

[0079] The following examples are intended to further describe certain non-limiting embodiments without limiting the scope of the invention. Those skilled in the art will recognize that variations of the following examples are possible within the scope of the invention, which is defined solely by the claims.

[0080] Example 1 Two alloys were produced with compositions that predicted limited cold formability. The compositions of these alloys in weight percent and their observed rollability are shown in Table 1. [Table 1]

[0081] The alloy was melted by non-consumable arc melting and cast into buttons. Subsequent hot rolling was performed in the beta phase field, followed by rolling in the alpha-beta phase field to produce a microstructure suitable for cold rolling. During this hot rolling process, the non-cobalt-containing alloy failed catastrophically due to lack of ductility. In comparison, the cobalt-containing alloy could be successfully hot rolled from a thickness of approximately 0.5 inches to a thickness of approximately 0.15 inches. The cobalt-containing alloy was then cold rolled.

[0082] The cobalt-containing alloy was then cold rolled to a final gauge of less than 0.76 mm (0.030 inch) with subsequent intermediate annealing and conditioning. Cold rolling was continued until a 0.635 cm (0.25 inch) long crack appeared, defined herein as a "large crack." The reduction achieved during cold working before edge cracking was observed, i.e., the cold reduction ductility limit, was recorded. Surprisingly, it was observed that the cobalt-containing alpha-beta titanium alloy in this example could be successfully hot rolled and subsequently cold rolled to at least a 25% cold reduction without large cracks, whereas the comparative alloy without cobalt addition could not be hot rolled without catastrophic failure.

[0083] Example 2 The mechanical performance of a second alloy (heat 5) within the scope of this disclosure was compared to a small coupon of Ti-4AI-2.5V alloy. Table 2 lists the composition of heat 5 and a Ti-4AI-2.5V heat (no Co) for comparison purposes. The compositions in Table 2 are listed in weight percent. [Table 2]

[0084] Buttons of Heat 5 and the comparative Ti-4Al-2.5V alloy were prepared by melting, hot rolling, and then cold rolling in the same manner as the cobalt-containing alloy of Example 1. Yield strength (YS), ultimate tensile strength (UTS), and percent elongation (%EI) were measured according to ASTM E8 / E8M-13a and are listed in Table 2. Both alloys were cold rolled. The strength and ductility (% EI) of Heat 5 were superior to those of the Ti-4Al-2.5V button.

[0085] Example 3 The cold rolling capability, or reduction ductility limit, was compared based on alloy composition. Buttons from alloy heats 1-4 were compared to buttons having the same composition as the Ti-4Al-2.5V alloy used in Example 2. The buttons were prepared by melting, hot rolling, and then cold rolling using the method used for the cobalt-containing alloy in Example 1. The buttons were cold rolled until significant cracking was observed, i.e., until the cold work reduction ductility limit was reached. Table 3 lists the compositions of the inventive and comparative buttons (the balance being titanium and incidental impurities) in weight percent, and the cold work reduction ductility limit, expressed as the % reduction of the hot-rolled buttons. [Table 3]

[0086] From the results in Table 3, it is observed that higher oxygen contents can be tolerated without loss of cold ductility in cobalt-containing alloys. The alpha-beta titanium alloy heats of the present invention (heats 1-4) exhibited better cold reduction ductility limits than the Ti-4Al-2.5V alloy buttons. By comparison, it should be noted that Ti-6Al-4V alloy cannot be commercially cold rolled without the onset of cracking and typically contains 0.14-0.18 wt.% oxygen. These results clearly demonstrate that the cobalt-containing alpha-beta alloys of the present invention surprisingly exhibit strength and cold ductility at least comparable to that of Ti-4Al-2.5V alloy, strength comparable to that of Ti-6Al-4V alloy, and cold ductility that is clearly superior to that of Ti-6Al-4V alloy.

[0087] In Table 2, the cobalt-containing alpha-beta titanium alloys of the present disclosure exhibit greater ductility and strength than Ti-4AI-2.5V alloy. The results set forth in Tables 1-3 show that the cobalt-containing alpha-beta titanium alloys of the present disclosure exhibit significantly greater cold ductility than Ti-6AI-4V alloy, despite having 33-66% more interstitial elements, which tend to reduce ductility.

[0088] It was unexpected that the addition of cobalt could improve the cold rolling performance of alloys containing high levels of interstitial alloying elements such as oxygen. From the viewpoint of one skilled in the art, it was unexpected that the addition of cobalt could improve cold rollability without reducing strength levels. The art has shown that Ti3X type (X represents the metal) intermetallic precipitates typically significantly reduce cold rollability, and that cobalt does not significantly improve strength or ductility. Most alpha-beta titanium alloys contain about 6% aluminum, which, when combined with cobalt additions, can form Ti3Al, which can have a negative effect on ductility.

[0089] The results presented hereinabove surprisingly show that the addition of cobalt actually improves ductility and strength in the titanium alloys of the present invention compared to Ti-4Al-2.5V alloy and other cold deformable alpha+beta alloys. Embodiments of the alloys of the present invention include combinations of alpha stabilizing elements, beta stabilizing elements, and cobalt.

[0090] The addition of cobalt, in combination with other alloying additions, appears to enable the alloys of the present disclosure to have high oxygen tolerance without adversely affecting ductility or cold workability. Previously, high oxygen tolerance has not been simultaneously correlated with cold workability and high strength.

[0091] Maintaining a high level of alpha phase in the alloy may allow the cobalt-containing alloy to preserve its machinability compared to other alloys with a higher beta phase content, such as Ti-5553, Ti-3553, and SP-700. Cold rollability also improves the degree of dimensional control and control over the achievable surface finish compared to other high-strength alpha-beta titanium alloys that cannot be cold-deformed in factory-produced products.

[0092] It will be understood that this specification describes those aspects of the invention that are relevant for a clear understanding of the invention. Certain aspects that would be obvious to those of ordinary skill in the art and that, as a result, would not aid in a better understanding of the invention have not been presented for the sake of brevity of this specification. While necessarily only a limited number of embodiments of the invention have been described herein, those skilled in the art will recognize, in light of the foregoing description, that numerous modifications and variations of the invention are possible. All such variations and modifications of the invention are intended to be covered by the foregoing description and the following claims. [Mode of the invention] [1] In weight percent: Aluminum equivalent ranging from 2.0 to 10.0; Molybdenum equivalent ranging from 0 to 20.0; 0.3-5.0 cobalt; titanium; and unavoidable impurities; An alpha-beta titanium alloy containing [2] The alpha-beta titanium alloy of [1], wherein the molybdenum equivalent is in the range of 2.0 to 20.0. [3] 10. The alpha-beta titanium alloy of [1], wherein the alpha-beta titanium alloy exhibits a cold work reduction ductility limit of at least 25%. [4] 10. The alpha-beta titanium alloy of [1], wherein the alpha-beta titanium alloy exhibits a cold work reduction ductility limit of at least 35%. [5] The alpha-beta titanium alloy of [1], wherein the alpha-beta titanium alloy exhibits a yield strength of at least 130 KSI (896.3 MPa) and an elongation of at least 10%.[6] Cerium, praseodymium, neodymium, samarium, gadolinium, holmium, erbium An alpha-beta titanium alloy according to [1], further containing more than 0 and up to 0.3 weight percent in total of one or more of tungsten, thulium, yttrium, scandium, beryllium, and boron. [7] The alpha-beta titanium alloy of [6], wherein the molybdenum equivalent is in the range of 0 to 10.[8] An alpha-beta titanium alloy according to [1], further containing more than 0 and up to 0.5 weight percent in total of one or more of gold, silver, palladium, platinum, nickel, and iridium. [9] The alpha-beta titanium alloy of [8], wherein the aluminum equivalent is in the range of 1.0 to 6.0 and the molybdenum equivalent is in the range of 0 to 10.

[10] An alpha-beta titanium alloy according to [6], further containing more than 0 and up to 0.5 weight percent in total of one or more of gold, silver, palladium, platinum, nickel, and iridium.

[11] Tin from 0 to 6; silicon from greater than 0 to 0.6; and Zirconium from 0 to 10; The alpha-beta titanium alloy of [1], further containing one or more of:

[12] In weight percent: 2.0~7.0 aluminum; Molybdenum equivalent ranging from 2.0 to 5.0; 0.3-4.0 cobalt; Oxygen up to 0.5; Nitrogen up to 0.25; up to 0.3 carbon; Maximum 0.4 unavoidable impurities; and titanium; An alpha-beta titanium alloy containing

[13] Tin from 0 to 6; Silicon greater than 0 up to 0.6; Zirconium from 0 to 10; Palladium from greater than 0 to 0.3; and Boron from greater than 0 to 0.5; The alpha-beta titanium alloy of

[12] , further comprising one or more of:

[14] An alpha-beta titanium alloy according to

[12] , further containing greater than 0 and up to 0.3 weight percent in total of one or more of cerium, praseodymium, neodymium, samarium, gadolinium, holmium, erbium, thulium, yttrium, scandium, beryllium, and boron.

[15] An alpha-beta titanium alloy according to

[12] , further containing more than 0 and up to 0.5 weight percent in total of one or more of gold, silver, palladium, platinum, nickel, and iridium.

[16] The alpha-beta titanium alloy of

[12] , wherein the alpha-beta titanium alloy exhibits a cold work reduction ductility limit of at least 25%.

[17] the alpha-beta titanium alloy exhibits a cold work reduction ductility limit of at least 35%;

[12] alpha-beta titanium alloy.

[18] The alpha-beta titanium alloy of

[12] , wherein the alpha-beta titanium alloy exhibits a yield strength of at least 130 KSI (896.3 MPa) and an elongation of at least 10%.

[19] 1. A method of forming an article from a metal forming article comprising an alpha-beta titanium alloy, comprising cold working the metal forming article to a reduction in area of ​​at least 25%, The metal molding comprises an alpha-beta titanium alloy of [1]; said metal forming product does not exhibit significant cracking after cold working; A method for forming said article.

[20]

[19] The method of

[19] , wherein cold working the metal part comprises cold working the metal part to a reduction of at least 35%. [twenty one]

[19] The method of

[19] , wherein cold working the metal formed article comprises one or more of rolling, forging, extrusion, pilger rolling, swinging, drawing, flow turning, liquid compression molding, gas compression molding, hydroforming, bulge forming, roll forming, stamping, fine blanking, die pressing, deep drawing, coining, spinning, swaging, impact extrusion, explosive forming, rubber forming, reverse extrusion, piercing, stretch forming, press bending, electromagnetic forming, and cold heading. [twenty two]

[19] The method of

[19] , wherein cold working the metal part comprises cold rolling. [twenty three]

[19] The method of

[19] , wherein cold working the metal part comprises working the metal part at a temperature of less than about 1250°F (676.7°C). [twenty four]

[19] The method of

[19] , wherein cold working the metal part comprises working the metal part at a temperature of about 575°F (300°C) or less. [twenty five]

[19] The method of

[19] , wherein cold working the metal part comprises working the metal part at a temperature of less than about 392°F (200°C).

[26]

[19] The method of

[19] , wherein cold working the metal formed product comprises working the metal formed product at a temperature in the range of -100°C to 200°C.

[27] The method of

[19] , wherein the metal shaped product is selected from an ingot, billet, bloom, beam, bar, tube, slab, rod, wire, plate, sheet, extrusion, and casting.

[28]

[19] The method of

[19] , further comprising hot working the metal formed article prior to cold working the metal formed article.

[29] In weight percent: 2.0~7.0 aluminum; Molybdenum equivalent ranging from 2.0 to 5.0; 0.3-4.0 cobalt; Oxygen up to 0.5; Nitrogen up to 0.25; up to 0.3 carbon; Maximum 0.4 unavoidable impurities; and titanium; providing an alpha-beta titanium alloy comprising: cold working the alpha-beta titanium alloy to a rolling reduction of at least 25%, wherein the alpha-beta titanium alloy does not exhibit significant cracking after cold working; 1. A method for forming an article from an alpha-beta titanium alloy, comprising:

[30]

[29] The method of

[29] , wherein cold working the alpha-beta titanium alloy comprises cold working the alpha-beta titanium alloy to a reduction of at least 35%.

[31]

[29] The method of

[29] , wherein cold working the alpha-beta titanium alloy comprises one or more of rolling, forging, extrusion, pilger rolling, swinging, drawing, flow turning, liquid compression molding, gas compression molding, hydroforming, bulge forming, roll forming, stamping, fine blanking, die pressing, deep drawing, coining, spinning, swaging, impact extrusion, explosive forming, rubber molding, reverse extrusion, piercing, stretch forming, press bending, electromagnetic forming, and cold heading.

[32]

[29] The method of

[29] , wherein cold working the alpha-beta titanium alloy comprises cold rolling the alpha-beta titanium alloy.

[33]

[34] The method of

[29] , wherein cold working the alpha-beta titanium alloy comprises working the alpha-beta titanium alloy at a temperature of less than about 1250°F (676.7°C).

[29] The method of

[29] , wherein cold working the alpha-beta titanium alloy comprises working the alpha-beta titanium alloy at a temperature below about 392°F (200°C).

[35]

[29] The method of

[29] , wherein cold working the alpha-beta titanium alloy comprises working the alpha-beta titanium alloy at a temperature in the range of -100°C to 200°C.

[36]

[29] The method of

[29] , wherein the alpha-beta titanium alloy is in a form selected from an ingot, billet, bloom, beam, slab, bar, tube, rod, wire, plate, sheet, extrusion, and casting.

[37]

[29] The method of

[29] , further comprising hot working the alpha-beta titanium alloy prior to cold working the alpha-beta titanium alloy.

[38] In weight percent: Aluminum up to about 4.1; at least 2.1 vanadium; 0.3-5.0 cobalt; aluminum equivalent ranging from about 6.7 to 10.0; Molybdenum equivalent ranging from 0 to 20.0; titanium; and unavoidable impurities; An alpha-beta titanium alloy containing

[39] The alpha-beta titanium alloy of

[38] , wherein the molybdenum equivalent is in the range of 2.0 to 20.0.

[40] the alpha-beta titanium alloy exhibits a cold work reduction ductility limit of at least 25%;

[38] alpha-beta titanium alloy.

[41] An alpha-beta titanium alloy according to

[38] , wherein the alpha-beta titanium alloy exhibits a cold work reduction ductility limit of at least 35%.

[42] The alpha-beta titanium alloy of

[38] , wherein the alpha-beta titanium alloy exhibits a yield strength of at least 130 KSI (896.3 MPa) and an elongation of at least 10%.

[43] An alpha-beta titanium alloy according to

[38] , further containing greater than 0 and up to 0.3 wt.% in total of one or more of cerium, praseodymium, neodymium, samarium, gadolinium, holmium, erbium, thulium, yttrium, scandium, beryllium, and boron.

[44] The alpha-beta titanium alloy of

[43] , wherein the molybdenum equivalent is in the range of 0 to 10.

[45] An alpha-beta titanium alloy according to

[38] , further containing more than 0 and up to 0.5 wt. % in total of one or more of gold, silver, palladium, platinum, nickel, and iridium.

[46] An alpha-beta titanium alloy according to

[43] , further containing more than 0 and up to 0.5 wt. % in total of one or more of gold, silver, palladium, platinum, nickel, and iridium.

[47] Tin from 0 to 6; silicon from greater than 0 to 0.6; and Zirconium from 0 to 10; The alpha-beta titanium alloy of

[38] , further comprising one or more of:

[48] In weight percent: 2.0 to about 4.1 aluminum; at least 2.1 vanadium; aluminum equivalent ranging from about 6.7 to 10.0; Molybdenum equivalent ranging from 2.0 to 5.0; 0.3-4.0 cobalt; Oxygen up to 0.5; Nitrogen up to 0.25; up to 0.3 carbon; Maximum 0.4 unavoidable impurities; and titanium; An alpha-beta titanium alloy containing

[49] Tin from 0 to 6; Silicon greater than 0 up to 0.6; Zirconium from 0 to 10; Palladium from greater than 0 to 0.3; and Boron from greater than 0 to 0.5; The alpha-beta titanium alloy of

[48] further containing one or more of:

[50] One or more of cerium, praseodymium, neodymium, samarium, gadolinium, holmium, erbium, thulium, yttrium, scandium, beryllium, and boron An alpha-beta titanium alloy

[48] further containing more than 0 and up to 0.3 wt.% of the above in total.

[51] An alpha-beta titanium alloy according to

[48] , further containing more than 0 and up to 0.5 wt. % in total of one or more of gold, silver, palladium, platinum, nickel, and iridium.

[52] An alpha-beta titanium alloy according to

[48] , wherein the alpha-beta titanium alloy exhibits a cold work reduction ductility limit of at least 25%.

[53] An alpha-beta titanium alloy according to

[48] , wherein the alpha-beta titanium alloy exhibits a cold work reduction ductility limit of at least 35%.

[54]

[48] ​​An alpha-beta titanium alloy according to

[48] , wherein the alpha-beta titanium alloy exhibits a yield strength of at least 130 KSI (896.3 MPa) and an elongation of at least 10%.

Claims

1. In weight percent: 3.5 to 5.5 aluminum; 1.5 to 4.5 tin; 2-3.8 vanadium; 0.3 to 1.6 Cobalt; 0.2 to 1.2 iron 0.1 to 0.5 oxygen Molybdenum equivalent ([Mo]) in the range of 2.0 to 20.0 ｅｑ ), where [Mo] ｅｑ = [Mo] + 2 / 3 [V] + 3 [Mn + Fe + Ni + Cr + Cu + Be] + 1 / 3 [Ta + Nb + W]; and titanium An alpha-beta titanium alloy containing

2. 10. The alpha-beta titanium alloy of claim 1 comprising a molybdenum equivalent ranging from 2.0 to 10.

0.

3. 2. The alpha-beta titanium alloy of claim 1 comprising a molybdenum equivalent ranging from 2.0 to 5.

0.

4. 2. The alpha-beta titanium alloy of claim 1 containing 2.0 to 3.3 vanadium.

5. 2. The alpha-beta titanium alloy of claim 1, containing greater than unavoidable concentrations of molybdenum, manganese, nickel, chromium, copper, beryllium, tantalum, niobium, and tungsten.

6. 10. The alpha-beta titanium alloy of claim 1 containing 3.5 to 4.1% aluminum.

7. 2. The alpha-beta titanium alloy of claim 1, containing 0.14 to 0.5 oxygen.

8. 2. The alpha-beta titanium alloy of claim 1, containing 0.14 to 0.3% oxygen.

9. 10. The alpha-beta titanium alloy of claim 1, further comprising an aluminum equivalent in the range of 2.0 to 10.

0.

10. 2. The alpha-beta titanium alloy of claim 1, containing greater than unavoidable concentrations of zirconium, hafnium, nitrogen, carbon, gallium, and germanium.

11. In weight percent: Aluminum from 2.0 to 7.0; Tin greater than 0 and not greater than 6.0; Vanadium from 2.0 to 5.0; 0.3 to 5.0 Cobalt; 0.2 to 1.2 iron oxygen less than or equal to 0.5; and titanium An alpha-beta titanium alloy containing

12. 3.5 to 5.5 aluminum; 1.5 to 4.5 tin; Vanadium from 2.0 to 4.0; 0.3 to 1.6 Cobalt; 0.2 to 1.2 iron 0.1 to 0.3 oxygen; and titanium 12. The alpha-beta titanium alloy of claim 11, comprising:

13. Aluminum from 2.0 to 7.0; Tin greater than 0 and not greater than 6.0; Vanadium from 2.0 to 5.0; 0.3 to 5.0 Cobalt; 0.2 to 1.2 iron; Oxygen below 0.5; Nitrogen less than or equal to 0.25; 0.3 or less carbon; Titanium; and impurities The alpha-beta titanium alloy of claim 11, comprising:

14. 3.5 to 5.5 aluminum; 1.5 to 4.5 tin; Vanadium from 2.0 to 4.0; 0.3 to 1.6 Cobalt; 0.2 to 1.2 iron; 0.1 to 0.3 oxygen; Nitrogen less than or equal to 0.25; 0.3 or less carbon; Titanium; and impurities 14. The alpha-beta titanium alloy of claim 13, comprising:

15. In weight percent: Aluminum equivalent ([Al]) in the range of 2.0 to 10.0 ｅｑ ), where [Al] ｅｑ =[Al]+1 / 3[Sn]+1�6[Zr+Hf]+10[O+2N+C]+[Ga]+[Ge]; Molybdenum equivalent ([Mo]) in the range of 2.0 to 20.0 ｅｑ ), where []] ｅｑ =[[Mo]+2 / 3[V]+3[Mn+Fe+&+Cr+C+B]]+1 / 3[TW\L+W]; 0.3 to 5.0 Cobalt; Oxygen below 0.5; Nitrogen less than or equal to 0.25; 0.3 or less carbon; Titanium; and Inevitable impurities below 0.4 An alpha-beta titanium alloy containing

16. 16. The alpha-beta titanium alloy of claim 15, having an aluminum equivalent in the range of 2.0 to 6.

0.

17. 16. The alpha-beta titanium alloy of claim 15, having an aluminum equivalent weight in the range of 6.7 to 10.

0.

18. 16. The alpha-beta titanium alloy of claim 15, having a molybdenum equivalent ranging from 2.0 to 10.

0.

19. 16. The alpha-beta titanium alloy of claim 15, having a molybdenum equivalent in the range of 2.0 to 5.

0.

20. 16. The alpha-beta titanium alloy of claim 15, wherein the aluminum equivalent is in the range of 6.7 to 10.0 and the molybdenum equivalent is in the range of 2.0 to 10.

0.

21. 16. The alpha-beta titanium alloy of claim 15, comprising 0.3 to 4.0 weight percent cobalt.

22. 16. The alpha-beta titanium alloy of claim 15, comprising 0.3 to 1.6 weight percent cobalt.

23. 16. The alpha-beta titanium alloy of claim 15 comprising 2.0 to 7.0 weight percent aluminum.

24. 16. The alpha-beta titanium alloy of claim 15 comprising 2.0 to 5.5 weight percent aluminum.

25. 16. The alpha-beta titanium alloy of claim 15 containing greater than 0 and up to 6.0 weight percent tin.

26. 16. The alpha-beta titanium alloy of claim 15 containing greater than 0 and less than or equal to 4.5 weight percent tin.

27. 16. The alpha-beta titanium alloy of claim 15 containing no more than 0.2 weight percent incidental impurities.

28. In weight percent: Aluminum below 7.0; 0.3 to 5.0 Cobalt; tin not exceeding 6.0; Aluminum equivalent ([Al]) in the range of 2.0 to 10.0 ｅｑ ), where [Al] ｅｑ =[Al]+1 / 3[Sn]+1�6[Zr+Hf]+10[O+2N+C]+[Ga]+[Ge]; Molybdenum equivalent ([Mo]) in the range of 2.0 to 20.0 ｅｑ ), where []] ｅｑ =[[Mo]+2 / 3[V]+3[Mn+Fe+&+Cr+C+B]]+1 / 3[TW\L+W]; Oxygen below 0.5; Nitrogen less than or equal to 0.25; 0.3 or less carbon; Titanium; and Inevitable impurities below 0.4 An alpha-beta titanium alloy containing

29. 30. The alpha-beta titanium alloy of claim 28, having an aluminum equivalent weight in the range of 6.7 to 10.

0.

30. 30. The alpha-beta titanium alloy of claim 28, having a molybdenum equivalent in the range of 2.0 to 10.

0.

31. 30. The alpha-beta titanium alloy of claim 28, wherein the aluminum equivalent is in the range of 6.7 to 10.0 and the molybdenum equivalent is in the range of 2.0 to 10.

0.

32. 30. The alpha-beta titanium alloy of claim 28 comprising 0.3 to 4.0 weight percent cobalt.

33. 30. The alpha-beta titanium alloy of claim 28 containing up to 5.5 weight percent aluminum.

34. 30. The alpha-beta titanium alloy of claim 28 comprising up to 4.5 weight percent tin.

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