RU2616676C2 - High strength and ductility alpha/beta titanium alloy - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, specifically to alpha/beta titanium alloys with high strength and ductility. Alpha/beta titanium alloy contains, wt%: from 3.9 to 4.5, aluminium, from 2.2 to 3.0 vanadium, from 1.2 to 1.8 iron, from 0.24 to 0.30 oxygen, up to 0.08 carbon maximum, up to 0.05 nitrogen maximum, up to 0.015 hydrogen maximum, a total of up to 0.30 other elements: less than 0.005 of each of boron and yttrium, not more than 0.10 of each of tin, zirconium, molybdenum, chromium, nickel, silicon, copper, niobium, tantalum, manganese and cobalt, and balance is titanium and unintentional impurities.

EFFECT: alloy is characterized by high mechanical properties with reduced weight.

22 cl, 3 dwg, 3 tbl, 3 ex

Description

CROSS RELATIONS TO RELATED APPLICATIONS

[0001] This application is a continuation of the application, claiming priority according to section 35 of the Code of US laws § 120, on the jointly considered application for US patent serial No. 12/903851, filed October 13, 2010, under the name "Anchorages and Spare Anchorages Alpha / Beta Titanium Alloy with High Strength ", which is a continuation of the application, claiming priority according to section 35 of the Code of the laws of the United States § 120, on the jointly considered application for US patent serial No. 12/888699, filed September 23, 2010, under called “Fasteners and Spare Fasteners of High Strength Alpha / Beta Titanium Alloy”. The full disclosure of applications serial No. 12/903851 and 12/888699 is incorporated herein by reference.

BACKGROUND

FIELD OF TECHNOLOGY

[0002] The present invention relates to alpha / beta titanium alloys with high strength and ductility.

Description of the level of technology

[0003] Titanium alloys, typically having a high strength-to-mass ratio, are corrosion resistant and creep resistant at moderately high temperatures. For this reason, titanium alloys are used in aerospace and aeronautical engineering, defense, marine and automotive industries, including, for example, chassis support elements, engine frames, bulletproof armor, bodies and mechanical fasteners.

[0004] A reduction in the weight of an airplane or other vehicle results in fuel economy. Thus, for example, this is a powerful incentive in the aerospace industry to reduce aircraft mass. Titanium and titanium alloys are attractive materials for achieving weight reduction in the aviation industry due to the high strength-to-weight ratio. Most aerospace titanium alloy parts are made of Ti-6AI-4V alloy (ASTM Grade 5; UNS R56400; AMS 4928, AMS 4911), which is an alpha / beta titanium alloy.

[0005] Alloy Ti-6AI-4V is one of the most widely known titanium-based structural materials, which is estimated to account for more than 50% of the total titanium-based materials market. Ti-6AI-4V is used in a variety of industries that benefit from the favorable combination of low weight alloy, corrosion resistance and high strength at low and moderate temperatures. For example, Ti-6AI-4V is used to manufacture aircraft engine components, aircraft structural parts, mounts, high-performance automotive components, medical equipment components, sports equipment, components for use at sea, and components for chemical process equipment.

[0006] Cold rolled Ti-6AI-4V alloy steel is mainly used in a heat treatment state to improve ductility or in a state after solid solution treatment and aging (STA). As used herein, the term “heat treatment state to improve ductility” refers to the state of the titanium alloy after heat treatment “rolling annealing”, in which the workpiece is annealed at elevated temperature (for example, 1200-1500 ° F / 649-816 ° C) for about 1 -8 hours and cooled in calm air. Heat treatment to improve ductility is performed after heat treatment of the workpiece in the region of the α + β phase. Round rolled Ti-6AI-4V alloy having a diameter of 2 to 4 inches (5.08 to 10.16 cm) in the state of “heat treatment to improve ductility” has a minimum predetermined tensile strength of about 130 thousand pounds. per square inch (896 MPa) and a minimum specified yield strength of about 120 thousand pounds. per square inch (827 MPa), at room temperature. The plates in the state after heat treatment to improve the ductility of Ti-6AI-4V are often produced according to the specifications of AMS 4911, while the bars in the state of heat treatment to improve the ductility of Ti-6AI-4V are often produced according to the specifications of AMS 4928.

[0007] US Patent No. 5,980,655 (“the '655 patent”), which is hereby incorporated by reference in its entirety, discloses an alpha / beta titanium alloy that includes, by weight percent, from 2.90 to 5.00 aluminum, from 2 00 to 3.00 vanadium, 0.40 to 2.00 iron, 0.20 to 0.30 oxygen, incidental impurities and titanium.

Alpha / beta titanium alloys disclosed in patent No. 655, here referred to as "alloys No. 655". The composition of the industrial alloy within the '655 alloy nominally includes, in weight percent of the total weight of the alloy, 4.00 aluminum, 2.50 vanadium, 1.50 iron, 0.25 oxygen, incidental impurities and titanium, and may be referred to here as the alloy Ti-4AI-2.5V-1.5Fe-0.250.

[0008] Due to the difficulty of cold working the Ti-6AI-4V alloy, the alloy is typically machined (eg, forged, rolled, drawn, etc.) at elevated temperatures, mainly above the dissolution temperature α ₂ . The Ti-6AI-4V alloy cannot be effectively cold worked to increase strength, due, for example, to a high degree of cracking (i.e., failure of the workpiece) during cold deformation. However, as described in US patent application No. 2004/0221929, which is hereby incorporated by reference in its entirety, it is surprisingly and unexpectedly discovered that the '655 alloys have a sufficient degree of cold deformability / processability.

[0009] Surprisingly, ‘655 alloys can be cold worked to achieve high strength while maintaining a technologically advanced level of ductility. The technological level of ductility here determines the state in which the alloy has a relative elongation of more than 6%. In addition, the strength of ‘655 alloys is comparable to that which can be achieved for Ti-6AI-4V alloy. For example, as shown in Table 6 of Patent No. 655, the tensile strength for the Ti-6AI-4V alloy is 145.3 thousand pounds. per square inch (1002 MPa), while the tested alloy samples ‘655 had tensile strength in the range of 138.7-142.7 thousand pounds. per square inch (956.3-983.9 MPa).

[0010] The requirements for aerospace materials 6946 V (AMS 6946 V) provide a more limited range of chemical composition than described in patent formula ‘655. The alloys specified in AMS 6946B retain the ability to deform for a wider range of chemical composition limits according to patent No. 655, but the mechanical strength property is at a minimum permitted by the conditions of AMS 6946B lower than that due to the industrial alloy Ti-6AI-4V. For example, according to AMS-4911L, the minimum tensile strength for a 0.125-inch (3.175 mm) thick plate of Ti-6AI-4V alloy is 134 thousand pounds. per square inch (923.9 MPa), and the minimum yield strength is 126 thousand pounds. per square inch (868.7 MPa). For comparison, according to AMS 6946B, the minimum tensile strength for a 0.125 inch (3.175 mm) thick plate of Ti-4AI-2.5V-1.5Fe-0.250 alloy is 130 thousand pounds. per square inch (896.3 MPa), and the minimum yield strength is 115 thousand pounds. per square inch (792.9 MPa).

[0011] Given the continued need to reduce fuel consumption by reducing the weight of airplanes and other vehicles, there is a need to improve ductile alpha / beta titanium alloy, which preferably has mechanical properties comparable or superior to those inherent to alpha / beta titanium alloy Ti-6AI -4V.

SUMMARY OF THE INVENTION

[0012] According to an aspect of the present invention, an alpha / beta titanium alloy comprises, as a percentage of the total weight of the alloy: from 3.9 to 4.5 aluminum; 2.2 to 3.0 vanadium; from 1.2 to 1.8 iron; 0.24 to 0.30 oxygen; up to 0.08 carbon; up to 0.05 nitrogen; up to 0.015 hydrogen; titanium; and a total of up to 0.30 other items.

[0013] In accordance with another aspect of the present invention, an alpha / beta titanium alloy mainly comprises, in weight percent: 3.9 to 4.5 aluminum; 2.2 to 3.0 vanadium; from 1.2 to 1.8 iron; 0.24 to 0.30 oxygen; up to 0.08 carbon; up to 0.05 nitrogen; up to 0.015 hydrogen; titanium; and a total of up to 0.30 other items.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The characteristics and advantages of the alloy and related processes disclosed herein will be better understood by reference to the accompanying drawings, in which:

[0015] FIG. 1 is a graph of tensile strength and yield strength versus aluminum equivalent for a bar and wire, including non-limiting alloys in accordance with the present invention;

[0016] FIG. 2 is a graph of tensile strength and yield strength versus aluminum equivalent for 0.5 inch (1.27 cm) wire, including non-limiting alloys in accordance with the present invention; and

[0017] FIG. 3 is a graph of tensile strength, yield strength, and elongation versus aluminum equivalent for a 1 inch (2.54 cm) thick plate, including non-limiting alloys in accordance with the present invention.

[0018] The reader will appreciate the details described, as well as others, after considering the subsequent detailed description of certain alloy options and related methods that are not restrictive in accordance with the present invention.

DETAILED DESCRIPTION OF SOME EMBODIMENTS EMBODIMENTS WITHOUT RESTRICTIVE CHARACTER

(0019] In the present description, which is not restrictive, other than in the functioning examples, or, unless otherwise indicated, all numbers expressing quantities or characteristics are to be understood as being corrected in all examples by the term “about.” Accordingly, if not otherwise indicated, any numerical parameters set forth in the following description are approximate and may vary depending on the desired properties that are sought to be obtained in these materials and by the methods in accordance with the present invention. m and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits, applying ordinary rounding techniques.

[0020] Any patents, publications or other materials disclosing information that are considered to be included in full or in part, by reference, are included here only to the extent that the information included does not contradict the existing definitions, representations or other materials set forth in this description. Thus, and to the extent necessary, the disclosure of the information set forth in this document supersedes any conflicting material incorporated herein by reference. Any material, or part thereof, incorporated herein by reference, but contrary to existing definitions, statements or other materials disclosing the information set forth herein, is included only to the extent that there is no conflict between the included material and the existing material of the invention.

[0021] Non-limiting alpha / beta titanium alloys, in accordance with the present invention, contain, consist, or mainly consist of (in weight percent): from 3.9 to 4.5 aluminum; 2.2 to 3.0 vanadium; from 1.2 to 1.8 iron; 0.24 to 0.30 oxygen; up to 0.08 carbon; up to 0.05 nitrogen; up to 0.015 hydrogen; titanium; and a total of up to 0.30 other items. In some non-restrictive embodiments of the present invention, other elements that may be present in the alpha / beta titanium alloy (as part of other elements comprising up to 0.30 weight percent) include one or more elements of boron, tin, zirconium, molybdenum, chromium, nickel, silicon, copper, niobium, tantalum, manganese, yttrium and cobalt, and in some non-limiting embodiments, the weight content of each other element present is 0.10 silt and less, but with two exceptions. Exceptions are boron and yttrium, which, present among other elements, are presented in a separate concentration of less than 0.005 weight percent.

I. Alloy Composition

[0022] Non-limiting alloys in accordance with the present invention include titanium, aluminum, vanadium, iron, and oxygen. If only alloying elements are discussed in the composition, discussed below, it should be understood that the rest includes titanium and incidental impurities.

A. Aluminum

[0023] Aluminum is an alpha phase hardening element in titanium alloys. The range of aluminum content in non-limiting alpha / beta titanium alloys in accordance with the present invention is narrower than the range of aluminum content disclosed in patent No. 655. In addition, the minimum level of aluminum in accordance with some non-limiting alloys in accordance with the present invention is greater than the minimum level set in AMS 6946B. It was noted that the compositional features allow the alloy to more consistently demonstrate mechanical properties comparable to the Ti-6AI-4V alloy. The minimum aluminum content in alpha / beta titanium alloys in accordance with the present invention is 3.9 weight percent. The maximum aluminum content of alpha / beta titanium alloys in accordance with the present invention is 4.5 weight percent.

V. Vanadium

[0024] Vanadium is an element that stabilizes the beta phase in titanium alloys. The minimum content of vanadium in alpha / beta titanium alloys in accordance with the present invention is greater than the minimum content disclosed in patent No. 655 and established in AMS 6946B. It was noted that such compositional features provide an optimal, controlled ratio of volume fractions of alpha and beta phases. The ratio of alpha and beta phases creates an alloy, in accordance with the present invention, with remarkable ductility and deformation ability. Vanadium is present in alpha / beta titanium alloys in accordance with the present invention in a minimum concentration of 2.2 weight percent. The maximum vanadium content in alpha / beta titanium alloys in accordance with the present invention is 3.0 weight percent.

C. Iron

[0025] Iron is an element that stabilizes the eutectoid beta phase in titanium alloys. Alpha / beta titanium alloys in accordance with the present invention include a larger minimum content and a narrower range of iron content compared with the alloy disclosed in patent No. 655. It was noted that this property provides an optimal, controlled ratio of volume fractions of alpha and beta phases. The ratio creates alloys, in accordance with the present invention, with remarkable ductility and deformation ability. Iron is present in alpha / beta titanium alloys in accordance with the present invention at a minimum concentration of 1.2 weight percent. The maximum iron content of alpha / beta titanium alloys in accordance with the present invention is 1.8 weight percent.

D. Oxygen

[0026] Oxygen is an element that strengthens the alpha phase in titanium alloys. The range of oxygen in alpha / beta titanium alloys in accordance with the present invention is less than the range disclosed in patent No. 655 and established in AMS 6946B. In addition, the minimum oxygen content in non-restrictive alloys in accordance with the present invention is greater than in patent No. 655 and in technical specifications AMS 6946B. It was noted that such compositional features allow the alloy, in accordance with the present invention, to consistently demonstrate mechanical properties comparable to the mechanical properties of the Ti-6AI-4V alloy. The minimum oxygen content in alpha / beta titanium alloys in accordance with the present invention is 0.24 weight percent. The maximum oxygen content in alpha / beta titanium alloys in accordance with the present invention is 0.30 weight percent.

[0027] In addition to the inclusion of titanium, aluminum, vanadium, iron, and oxygen, as discussed previously, some non-limiting alpha / beta titanium alloys according to the present invention include other elements in a total concentration not exceeding 0, 30 weight percent. In some non-restrictive embodiments, these other elements include one or more of a number of elements: boron, tin, zirconium, molybdenum, chromium, nickel, silicon, copper, niobium, tantalum, manganese, yttrium and cobalt, among which with the exception of two, the weight percent of each such element is 0.10 or less. Exceptions are boron and yttrium. In the case of the presence in the alloys in accordance with the present invention, the weight percent of each of the elements, boron and yttrium, is less than 0.005.

[0028] In accordance with the present invention, in addition to the alpha / beta titanium alloys, random impurities may be present. For example, carbon may be present in an amount up to 0.008 weight percent. Nitrogen may be present in an amount up to 0.05 weight percent. Hydrogen may be present in an amount up to 0.015 weight percent. Other possible incidental impurities may be apparent to those skilled in the metallurgy industry.

[0029] Table 1 provides information on the composition of (i) certain, non-limiting, alpha / beta titanium alloys in accordance with the present invention and (ii) certain alloys disclosed in patent No. 655 and stipulated in AMS 6946B.

Table 1 Alloy Compositions Alloying element Weight percent Non-limiting embodiments of the present invention U.S. Patent 5,980,655 AMS 6946B Aluminum from 3.9 to 4.5 from 2.5 to 5.4 from 3.5 to 4.5 Vanadium from 2.2 to 3.0 from 2.0 to 3.4 from 2.0 to 3.0 Iron from 1.2 to 1.8 from 0.2 to 2.0 from 1.2 to 1.8 Oxygen from 0.24 to 0.30 from 0.2 to 0.3 from 0.20 to 0.30 Carbon 0.08 max. 0.1 max 0.08 max.

Nitrogen 0.05 max. 0.1 max 0.03 max. Hydrogen 0.015 max not indicated 0.015 max other items 0.10 max. each, 0.30 max. in total 0.10 max. each, in total not indicated 0.10 max. each, 0.30 max. total

[0030] The inventors of the present invention unexpectedly found that the creation of the present alloy with minimum levels of aluminum, oxygen and iron greater than the minimum levels specified in the '655 patent provides an alpha / beta titanium alloy that sequentially exhibits mechanical properties, such as as strength, at least comparable to certain mechanical properties of the alloy Ti-6AI-4V in the state after heat treatment to improve ductility. In addition, the authors unexpectedly found that increasing the minimum levels and narrowing the ranges of iron and vanadium relative to the minimum levels and ranges disclosed in the '655 patent, creates alloys that have an optimal and controlled ratio of volume fractions of alpha and beta phases in a heat-treated state for ductility improvements. Such an optimal phase ratio in alpha / beta titanium alloys in accordance with the present invention creates alloys with improved ductility compared to Ti-6AI-4V alloys, while maintaining the ductility of the alloys disclosed in patent No. 655 and stipulated in AMS 6946B.

[0031] One skilled in the art will recognize that the strength and ductility of metallic materials mainly has an inverse relationship. In other words, if the strength of a metal material increases, its ductility decreases. The combination of increased mechanical strength and retained ductility in alpha / beta titanium alloys in accordance with the present invention was unexpected, since the inverse relationship between strength and ductility is typically observed for titanium alloys after heat treatment to improve ductility. An unexpected and surprising combination of increased mechanical strength and retained ductility is a particularly advantageous characteristic of the alloys of the present invention. It was noted with surprise that the variants of the alloys after heat treatment to improve ductility in accordance with the present invention have a strength comparable to Ti-6AI-4V alloys, while not reducing ductility.

[0032] It was noted that some non-limiting alpha / beta alloys according to the present invention having an aluminum equivalent value (Al _eq ) of at least 6.3 or more, preferably at least 6 , 4, had a strength of at least comparable to that of Ti-6AI-4V alloys. In addition, it was observed that such alloys had ductility superior to that of Ti-6AI-4V alloys, which typically have an aluminum equivalent of about 7.5. As used herein, the term “aluminum equivalent value” or “aluminum equivalent” (Al _eq ) means: a value equal to the aluminum content in weight percent in the alloy, plus ten times the oxygen content in weight percent in the alloy. In other words, the aluminum equivalent of the alloy can be defined as: Al _eq = Al _(wt.%) +10 (O _(wt.%) ).

[0033] While it is recognized that the mechanical properties of titanium alloys are largely dependent on the size of the test sample, in non-limiting embodiments, in accordance with the present invention, the alpha / beta titanium alloy includes an aluminum equivalent of at least a level 6.4, or in some embodiments, in the range of 6.4 to 7.2, and a yield strength of at least 120 thousand pounds per square inch (827.4 MPa), or in a specific embodiment, at least 130 thousand. pound per square inch (896.3 MPa).

[0034] In other non-limiting embodiments, in accordance with the present invention, the alpha / beta titanium alloy includes an aluminum equivalent of at least 6.4, or in some embodiments, in the range of 6.4 to 7.2 and yield strength in the range from 120 thousand pounds per square inch (827.4 MPa) to 155 thousand pounds per square inch (1069 MPa).

[0035] In other non-limiting embodiments, in accordance with the present invention, the alpha / beta titanium alloy includes an aluminum equivalent of at least 6.4, or in some embodiments, in the range of 6.4 to 7.2 and a tensile strength of at least 130 thousand pounds per square inch (896.3 MPa), or in some embodiments at least 140 thousand pounds per square inch (965.3 MPa).

[0036] In additional, non-limiting embodiments, in accordance with the present invention, the alpha / beta titanium alloy includes an aluminum equivalent of at least 6.4, or in some embodiments, in the range of 6.4 to 7, 2, and a tensile strength in the range from 130 thousand pounds per square inch (896.3 MPa) to 165 thousand pounds per square. inch (1138 MPa).

[0037] In other non-limiting embodiments, in accordance with the present invention, the alpha / beta titanium alloy includes an aluminum equivalent value of at least 6.4, or in some embodiments, in the range of 6.4 to 7, 2, and ductility of at least 12% or at least 16% (elongation).

[0038] In other non-limiting embodiments, in accordance with the present invention, the alpha / beta titanium alloy includes an aluminum equivalent value of at least 6.4, or in some embodiments, in the range of 6.4 to 7, 2, and ductility in the range from 12% to 30% (elongation or “% elongation”).

[0039] Whereas in accordance with some non-limiting embodiments of the present invention, 6.3 is the absolute minimum value for Al _eq , the inventors determined that to achieve the same strength that the T1-6AI alloy has -4V, an Al _eq value of at least 6.4 is required. In addition, it is obvious that in other non-limiting alpha / beta titanium alloy embodiments in accordance with the present invention, the maximum value for Al _eq is 7.5, and that here the strength to ductility ratio is used in accordance with others, not having the limitations disclosed herein.

[0040] According to a non-limiting embodiment, the alpha / beta titanium alloy according to the present invention includes an aluminum equivalent of at least 6.4, a yield strength of at least 120 thousand pounds per square inch. (827.4 MPa), a tensile strength of at least 130 thousand pounds per square inch (896.3 MPa), and ductility of at least 12% (elongation).

[0041] In accordance with another non-limiting embodiment, the alpha / beta titanium alloy in accordance with the present invention includes an aluminum equivalent of at least 6.4, a yield strength of at least 130 thousand pounds per square kilometer. . inch (896.3 MPa), tensile strength of at least 140 thousand pounds per square inch (965.3 MPa), and ductility of at least 12%.

[0042] In another non-limiting embodiment, the alpha / beta titanium alloy in accordance with the present invention includes an aluminum equivalent in the range of 6.4 to 7.2, a yield strength in the range of 120 thousand pounds per sq. inch (827.4 MPa) to 155 thousand pounds per square inch (1069 MPa), tensile strength in the range from 130 thousand pounds per square inch (896.3 MPa) to 165 thousand pounds per square inch (1138 MPa), and ductility in the range from 12% to 30% (elongation).

[0043] In one non-limiting embodiment, the alpha / beta titanium alloy according to the present invention has an average tensile strength (UTS) satisfying the equation:

UTS≥14.767 (Al _eq ) +48.001.

[0044] In another, non-limiting embodiment, the alpha / beta titanium alloy in accordance with the present invention has an average yield strength (YS) satisfying the equation:

YS≥13.338 (Al _eq ) +46.864.

[0045] In yet another non-limiting embodiment, the alpha / beta titanium alloy according to the present invention has an average ductility of:

% el≥3.3669 (Al _eq ) -1.9417.

[0046] In yet another non-limiting embodiment, the alpha / beta titanium alloy according to the present invention has an average tensile strength (UTS) satisfying the equation:

UTS≥14.767 (Al _eq ) +48.001;

average yield strength (YS) satisfying the equation:

YS> 13.338 (Al _eq ) +46.864;

and medium ductility satisfying the equation;

% e1> 3.3669 (Al _eq ) -1.9417.

[0047] In one non-limiting embodiment, the alpha / beta titanium alloy according to the present invention has an average tensile strength (UTS) satisfying the equation:

UTS≥12.414 (Al _eq ) +64.429.

[0048] In another, non-limiting embodiment, the alpha / beta titanium alloy according to the present invention has an average yield strength (YS) satisfying the equation:

YS≥13.585 (Al _eq ) +44.904.

[0049] In yet another non-limiting embodiment, the alpha / beta titanium alloy according to the present invention has an average ductility of:

% el≥4.1993 (Al _eq ) -7.4409.

[0050] In yet another non-limiting embodiment, the alpha / beta titanium alloy according to the present invention has an average tensile strength (UTS) satisfying the equation:

UTS≥12.414 (Al _eq ) +64.429;

average yield strength (YS) satisfying the equation:

YS≥13.585 (Al _eq ) +44.904;

and average ductility satisfying the equation:

% el≥4.1993 (Al _eq ) -7.4409.

[0051] In one non-limiting embodiment, the alpha / beta titanium alloy according to the present invention has an average tensile strength (UTS) satisfying the equation:

UTS≥10.087 (Al _eq ) +76.785.

[0052] In another, non-limiting embodiment, the alpha / beta titanium alloy according to the present invention has an average yield strength (YS) satisfying the equation:

YS≥13.911 (Al _eq ) +39.435.

[0053] In yet another non-limiting embodiment, the alpha / beta titanium alloy according to the present invention has an average ductility of:

% el≥1.1979 (Al _eq ) +8.5604.

[0054] In yet another non-limiting embodiment, the alpha / beta titanium alloy according to the present invention has an average tensile strength (UTS) satisfying the equation:

UTS≥10.087 (Al _eq ) +76.785;

average yield strength (YS) satisfying the equation:

YS≥13.911 (Al _eq ) +39.435;

and average ductility expressed by elongation (% el) satisfying the equation:

% el≥1.1979 (Al _eq ) +8.5 604.

[0055] It has been determined that non-limiting alpha / beta titanium alloys according to the present invention exhibit comparable or increased mechanical strength, increased ductility, and improved deformability compared to Ti-6AI-4V. Therefore, there is the possibility of using products made from alloys in accordance with the present invention as a replacement for products from Ti-6AI-4V alloy in the aerospace, aviation industry, for marine applications, in the automotive and other industries. The high strength and ductility of the alloy options, in accordance with the present invention, allows to produce certain types of rolled products and end products with tight tolerances, which currently cannot be made from TI-6AI-4V alloy.

[0056] An aspect of the present invention is directed to articles made and / or made of an alloy in accordance with the present invention. Some non-restrictive products may be selected from aircraft engine components, aircraft structural components, automobile components, medical equipment components, sports equipment components, components used at sea, and chemical process equipment components. Other products may consist and / or be made of variants of alpha / beta titanium alloys, in accordance with the present invention, which are known now or in the future specialist, in the scope of the disclosed here. Products consisting and / or made of alloys in accordance with the present invention, through shaping and other manufacturing techniques known to specialists in this field at present or in the future.

[0057] The following examples are intended to further describe some non-restrictive variations without limiting the scope of the present invention. Specialists in this field it is clear that changes are possible in the following examples, as well as other options not described here, in the scope of the invention, which is defined solely by the claims.

EXAMPLE 1

[0058] Alpha / beta titanium alloy ingots having the composition of the present invention were cast using conventional vacuum arc smelting (VAR), plasma arc smelting (PAM), or cold hearth electron beam smelting (EB) for primary remelting, and remelting using VAR. The composition of the ingots was in the range shown in the column "Non-restrictive options in accordance with the present invention" included in the above Table 1.

[0059] The composition of the ingots produced in this Example 1 had aluminum equivalent values ranging from about 6.0 to about 7.1. The ingots were processed using various types of hot rolling technology into hot rolled bars and wire having diameters from 0.25 inch (0.635 cm) to 3.25 inch (8.255 cm). Hot rolling was performed at initial temperatures between 1550 ° F (843.3 ° C) and 1650 ° F (898.9 ° C). This temperature range is below the alpha / beta transition temperature of the alloys of this example, which is about 1750 ° F to 1850 ° F (about 954.4 ° C to 1010 ° C), depending on the actual chemical composition. After hot rolling, the hot rolled bars and wire were annealed at 1275 ° F (690.6 ° C) for one hour, followed by cooling in air. The diameter, aluminum content, iron content, oxygen content and the calculated Al _{eq of} each bar and wire sample produced in Example 1 are presented in Table 2.

table 2 Sample No. Diameter (inch) Al (wt.%) Fe (wt.%) O (wt.%) Al _eq (Al% + 10⋅O%) one 3.25 4.07 1,56 0.25 6.53 2 3.25 4.10 1.77 0.19 5.96 3 3.25 4.27 1.90 0.19 6.13 four 2 4.05 1,54 0.25 6.57 5 2 4.05 1.55 0.25 6.58

6 2 4.26 1.88 0.21 6.38 7 one 4.35 1.44 0.24 6.74 8 one 4.36 1.28 0.27 7.08 9 0.5 4.38 1.24 0.28 7.15 10 0.5 4.33 1.42 0.25 6.81 eleven 0.5 4.14 1.47 0.24 6.51 12 0.344 4.37 1,50 0.26 6.95 13 0.25 3.93 1,58 0.23 6.27 fourteen 0.25 4.12 1,56 0.25 6.65 fifteen 0.25 4.40 1.35 0.27 7.10 16 0.25 3.95 1,53 0.24 6.30 17 0.25 4.33 1.35 0.27 7.06

[0060] In FIG. Figure 1 graphically shows (at room temperature) the tensile strength (UTS), yield strength (YS), and elongation (% el) for bar and wire samples shown in Table 2, depending on the size of the aluminum equivalent of the alloy in the sample. FIG. 1 also includes trend lines through the data points UTS, YS, and% el determined by linear regression analysis. It is seen that the average strength and the average elongation increases with increasing Al _eq . This relationship is surprising and unexpected, since it contradicts the commonly observed relationship, when an increase in strength is accompanied by a decrease in ductility.

[0061] The typical minima of the Ti-6AI-4V alloy for UTS and YS are 135 thousand pounds per square inch (930.8 MPa) and 125 thousand pounds per square inch (861.8 MPa), respectively. YS for the samples according to the invention shown in Table 2 ranges from about 125 thousand pounds per square inch for a sample with Al _{eq of} about 6.0 to about 141 thousand pounds per square inch for a sample with Al _{eq of} about 7 ,one. A sample having an Al _{eq of} about 6.4 showed a YS of about 130 thousand pounds per square inch (896.3 MPa). The UTS for the samples of the invention shown in Table 2 ranges from about 135 thousand pounds per square inch for a sample with Al _{eq of} about 6.0 to about 153 thousand pounds per square inch for a sample with Al _{eq of} about 7.1. A sample having an Al _{eq of} about 6.4 showed a YS of about 141 thousand pounds per square inch (972 MPa).

EXAMPLE 2

[0062] Wire samples No. 9-11 of Example 1, having a diameter of about 0.5 inches (1.27 cm) and an aluminum equivalent of about 6.5, about 6.8 and about 7.15, were subjected to tensile tests at room temperature. The results of tensile tests are depicted graphically in FIG. 2. All of these samples had tensile and yield strengths that were comparable to or higher than the strength of the industrial alloy Ti-6AI-4V. As in FIG. 1 from FIG. 2 it is obvious that an increase in Al _eq leads to an increase in strength, together with an increase in the average percent elongation. As discussed above, this trend is surprising and unexpected, since it contradicts the commonly observed relationship, when an increase in strength is accompanied by a decrease in ductility. There is less variation in the data in FIG. 2, which is typical for tests performed on samples of the same size, compared with FIG. 1, which is typical for tests performed on samples of various sizes, since the mechanical properties to some extent depend on the size of the test sample.

EXAMPLE 3

[0063] Samples of the hot rolled plate 1 inch (2.54 cm) thick were made from ingots made in accordance with the operations described in Example 1. The alloy ingots had a composition in the ranges given in the column “Non-limiting options in accordance with this invention ", included in the above Table 1, with the contents of aluminum and oxygen and the values of the aluminum equivalent shown in Table 3.

Table 3 Sample No. Diameter (inch) Al (wt.%) Fe (wt.%) O (wt.%) Al _eq (Al% + 10⋅O%) eighteen one 4.08 1,53 0.24 6.43 19 one 4.13 1.44 0.24 6.48 twenty one 4.22 1.49 0.29 7.12 21 one 4.25 1.40 0.28 7.05 22 one 4.21 1.38 0.29 7.08

[0064] All hot rolling temperatures were below the alpha / beta transition temperatures of the alloys. The alloys had Al _eq values of about 6.5 to 7.1. Tensile tests at room temperature were used to determine the tensile strength, yield strength and elongation (ductility). The results of tensile tests are depicted graphically in FIG. 3. From FIG. 3 it is evident that alloys including elevated A1 and O levels, as indicated by the calculated aluminum equivalents, have at room temperature a strength of at least comparable to the strength levels of the Ti-6AI-4V alloy. In addition, it was noted that strength increased with increasing Al _eq . In addition, the average ductility of the alloys of the invention either increased slightly or remained generally unchanged with increasing Al _eq and increasing strength. This trend is surprising and unexpected because it contradicts the commonly observed relationship, when an increase in strength is accompanied by a decrease in ductility.

[0065] The present description is written with reference to various typical, illustrative and non-restrictive variations. However, it will be understood by those skilled in the art that various substitutions, changes, or combinations of any of the disclosed embodiments (or parts thereof) can be made without departing from the scope of the invention defined solely by the claims. Thus, it is intended and understood that the present invention includes further variations not expressly set forth herein. Such options can be obtained, for example, by combining and / or modifying any of the disclosed steps, ingredients, constituents, components, elements, parameters, aspects, and the like in the embodiments described herein. Thus, this invention is not limited to describing various typical, illustrative and non-restrictive variations, but solely by the claims. Thus, it should be understood that the claims can be modified during the review process of this patent application in order to add new features to the claims, which are described differently here.

Claims (71)

1. Alpha / beta titanium alloy containing as a percentage by weight of the total mass of the alloy: from 3.9 to 4.5 aluminum; 2.2 to 3.0 vanadium; from 1.2 to 1.8 iron; 0.24 to 0.30 oxygen; up to 0.08 carbon maximum; up to 0.05 nitrogen maximum; up to 0.015 hydrogen maximum; the rest is titanium and up to a total of 0.30 other elements, with a total of up to 0.30 other elements include: less than 0.005 of each of boron and yttrium; not more than 0.10 of each of tin, zirconium, molybdenum, chromium, nickel, silicon, copper, niobium, tantalum, manganese and cobalt. 2. Alpha / beta titanium alloy according to claim 1, wherein the alloy has an aluminum equivalent value in the range of 6.45 to 7.2 and has a yield strength in the range of 132 thousand pounds per square. inch (910 MPa) to 155 thousand pounds per square. inch (1069 MPa). 3. The alpha / beta titanium alloy according to claim 1, wherein the alloy has an aluminum equivalent value in the range of 6.45 to 7.2 and has a tensile strength in the range of 142.5 thousand psi. inch (982.5 MPa) to 165 thousand pounds per square. inch (1138 MPa). 4. The alpha / beta titanium alloy according to claim 1, wherein the alloy has an aluminum equivalent value in the range of 6.45 to 7.2 and ductility in the range of 20 to 30 percent elongation. 5. Alpha / beta titanium alloy according to claim 1, wherein the alloy has an aluminum equivalent value in the range of 6.45 to 7.2, has a yield strength in the range of 132 thousand psi. inch (910 MPa) to 143.1 thousand pounds per square. inch (986.6 MPa), has a tensile strength in the range from 142.5 thousand pounds per square. inch (982.5 MPa) to 154.6 thousand pounds per square. inch (1066 MPa) and has ductility in the range of 20 to 22 percent elongation. 6. Alpha / beta titanium alloy, consisting of, in percent by weight of the total mass of the alloy: from 3.9 to 4.5 aluminum; 2.2 to 3.0 vanadium; from 1.2 to 1.8 iron; 0.24 to 0.30 oxygen; up to 0.08 carbon maximum; up to 0.05 nitrogen maximum; up to 0.015 hydrogen maximum; a total of up to 0.30 of other elements, with a total of up to 0.30 of other elements include: less than 0.005 of each of boron and yttrium; not more than 0.10 of each of tin, zirconium, molybdenum, chromium, nickel, silicon, copper, niobium, tantalum, manganese and cobalt; and the rest is titanium. 7. Alpha / beta titanium alloy according to claim 6, wherein the alloy has an aluminum equivalent value in the range of 6.45 to 7.2 and a yield strength in the range of 132 thousand psi. inch (910 MPa) to 155 thousand pounds per square. inch (1069 MPa). 8. The alpha / beta titanium alloy according to claim 6, wherein the alloy has an aluminum equivalent value in the range of 6.45 to 7.2 and has a tensile strength in the range of 142.5 thousand psi. inch (982.5 MPa) to 165 thousand pounds per square. inch (1138 MPa). 9. The alpha / beta titanium alloy according to claim 6, wherein the alloy has an aluminum equivalent value in the range of 6.45 to 7.2 and ductility in the range of 20 to 30 percent elongation. 10. The alpha / beta titanium alloy according to claim 6, wherein the alloy has an aluminum equivalent value in the range of 6.45 to 7.2, has a yield strength in the range of 132 thousand psi. inch (910 MPa) to 143.1 thousand pounds per square. inch (986.6 MPa), has a tensile strength in the range from 142.5 thousand pounds per square. inch (982.5 MPa) to 154.6 thousand pounds per square. inch (1066 MPa) and has ductility in the range of 20 to 22 percent elongation. 11. The product of alpha / beta titanium alloy, characterized in that it contains an alloy according to claim 1. 12. The product according to p. 11, characterized in that it consists of an alloy according to p. 1. 13. The product according to claim 11, wherein the product is selected from an aircraft engine component, an aircraft structural component, an automobile component, a medical device component, a sports equipment component, a component for marine applications, and a chemical processing equipment component. 14. The product according to claim 12, wherein the product is selected from an aircraft engine component, an aircraft structural component, an automobile component, a medical device component, a sports equipment component, a marine component, and a chemical processing equipment component. 15. The product of alpha / beta titanium alloy, characterized in that it contains an alloy according to claim 6. 16. The product according to p. 15, characterized in that it consists of an alloy according to p. 6. 17. The product according to claim 15, wherein the product is selected from an aircraft engine component, an aircraft structural component, an automobile component, a medical device component, a sports equipment component, a component for marine applications, and a chemical processing equipment component. 18. The product of claim 16, wherein the product is selected from an aircraft engine component, an aircraft structural component, an automobile component, a medical device component, a sports equipment component, a marine component, and a chemical processing equipment component. 19. Alpha / beta titanium alloy according to claim 1, while the average tensile strength (UTS) of alpha / beta titanium alloy in units of thousand pounds per square. Inch satisfies the equation: UTS≥14.767 (Al _eq ) +48.001, with a standard deviation of 0.6213; while the average yield strength (YS) of alpha / beta titanium alloy in units of thousand pounds per square. Inch satisfies the equation: YS≥13.338 (Al _eq ) +46.864, with a standard deviation of 0.4519; and while measured in percent elongation, the average ductility of the alpha / beta titanium alloy satisfies the equation: % el≥3.3669 (Al _eq ) -1.9417, with a standard deviation of 0.1746; moreover, Al _eq = aluminum in percent by weight + 10 (oxygen) in percent by weight. 20. Alpha / beta titanium alloy according to claim 6, while the average tensile strength (UTS) of alpha / beta titanium alloy in units of thousand pounds per square. Inch satisfies the equation: UTS≥14.767 (Al _eq ) +48.001, with a standard deviation of 0.6213; while the average yield strength (YS) of alpha / beta titanium alloy in units of thousand pounds per square. Inch satisfies the equation: YS≥13.338 (Al _eq ) +46.864, with a standard deviation of 0.4519; and while measured in percent elongation, the average ductility of the alpha / beta titanium alloy satisfies the equation: % el≥3.3669 (Al _eq ) -1.9417, with a standard deviation of 0.1746; moreover, Al _eq = aluminum in percent by weight + 10 (oxygen) in percent by weight. 21. Alpha / beta titanium alloy according to claim 1, while the average tensile strength (UTS) of alpha / beta titanium alloy in units of thousand pounds per square. Inch satisfies the equation: UTS≥12.414 (Al _eq ) +64.429, with a standard deviation of 0.9576; while the average yield strength (YS) of alpha / beta titanium alloy in units of thousand pounds per square. Inch satisfies the equation: YS≥13.585 (Al _eq ) +44.904, with a standard deviation of 0.8138; and while measured in percent elongation, the average ductility of the alpha / beta titanium alloy satisfies the equation: % el≥4.1993 (Al _eq ) -7.4409, with a standard deviation of 0.1731; moreover, Al _eq = aluminum in percent by weight + 10 (oxygen) in percent by weight. 22. Alpha / beta titanium alloy according to claim 6, while the average tensile strength (UTS) of alpha / beta titanium alloy in units of thousand pounds per square. Inch satisfies the equation: UTS≥12.414 (Al _eq ) +64.429, with a standard deviation of 0.9576; while the average yield strength (YS) of alpha / beta titanium alloy in units of thousand pounds per square. Inch satisfies the equation: YS≥13.585 (Al _eq ) +44.904, with a standard deviation of 0.8138; and while measured in percent elongation, the average ductility of the alpha / beta titanium alloy satisfies the equation: % el≥4.1993 (Al _eq ) -7.4409, with a standard deviation of 0.1731; moreover, Al _eq = aluminum in percent by weight + 10 (oxygen) in percent by weight.

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