Titanium alloy articles and methods of making titanium alloy articles

Abstract

Titanium alloy articles and methods of making titanium alloy articles are provided. The titanium alloy article comprises a first layer and a second layer. The first layer comprises a first titanium alloy and the second layer comprises a second titanium alloy. A metallurgical bond is between the first layer and the second layer. The first layer and the second layer differ in at least one measurable mechanical property.

Description

Attorney Docket No. 242401 PCTTITLE TITANIUM ALLOY ARTICLES AND METHODS OF MAKING TITANIUM ALLOY ARTICLESINVENTORSDavid C. BerryDavid ShanerCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Non-Provisional Patent Application No.19 / 265,543, filed on July 10, 2025, which claims the benefit of U.S. Provisional Patent Application No. 63 / 670,066, filed July 11, 2024, which are incorporated by reference herein in their entirety.BACKGROUND

[0002] Roll-bonded dual hardness armor plate has been developed for use in military and other applications. One example of a roll-bonded dual hardness armor plate that has been applied in military armor applications is ATI K12®-MIL Dual Hard armor plate, available from ATI Inc., Dallas, TX, USA. Given the importance of armor in military vehicles and other military applications, it is desirable to formulate armor plate providing improved resistance to ballistic projectile penetration and / or reduced weight. There are challenges associated with developing improved dual hardness armor plates and other articles.SUMMARY

[0003] A non-limiting aspect according to the present disclosure is directed to a titanium alloy article comprising a first layer and a second layer. The first layer comprises a first titanium alloy having a first hardness. The second layer comprises a second titanium alloy having a second hardness. The first hardness is 10 HBWto 100 HBW greater than the second hardness. A metallurgical bond is between the first layer and the second layer.

[0004] Another non-limiting aspect according to the present disclosure is directed to a titanium alloy article comprising a first layer and a second layer. The first layer comprises a first titanium alloy having a first hardness in a range of 300 HBW to 400 HBW. The second layer comprises a second titanium alloy having a second hardness in a range of 250 HBWto 370 HBW. The second hardness is less than the first hardness. A metallurgical is bond between the first titanium alloy and the second titanium alloy.

[0005] A further non-limiting aspect a method of making a titanium alloy article comprising a first layer and a second layer. The first layer comprises a first titanium alloy. The second layer comprises a second titanium alloy. A metallurgical bond is between the first titanium alloy and the second titanium alloy. The titanium alloy article exhibits at least one of the following: an Emof at least 1.38 when tested with 0.50 caliber AP M2; an Emof at least 1.37 when tested with 20 mm fragment simulating projectile; and an Emat least 5% greater than an Emof a homogeneous monolayer of a titanium alloy.

[0006] Another non-limiting aspect according to the present disclosure is directed to a method for manufacturing a titanium article. The method comprises disposing the first layer on the second layer so that at least a portion of the first layer contacts the second layer to thereby form an assembly. The method comprises metallurgically bonding the first layer to the second layer to thereby form a metallurgical bonded part.

[0007] It is understood that the inventions disclosed and described in this specification are not limited to the aspects summarized in this Summary. The reader will appreciate the foregoing details, as well as others, upon considering the following detailed description of various non-limiting and non-exhaustive aspects according to this disclosure.BRIEF DESCRIPTION OF THE FIGURES

[0008] The features and advantages of the examples presented herein, and the manner of attaining them, will become more apparent, and the examples will be better understood, by reference to the following description taken in conjunction with the accompanying figures, wherein:

[0009] FIG. 1 is a perspective view of a non-limiting embodiment of a titanium alloy article according to the present disclosure;

[0010] FIG. 2 is a side view of the titanium alloy article embodiment of FIG. 1 ; and

[0011] FIG. 3 is a flow chart of a non-limiting embodiment of a method of making a titanium alloy article according to the present disclosure.

[0012] The examples set out herein illustrate certain embodiments, in one form, and such examples are not to be construed as limiting the scope of the appended claims in any manner.DETAILED DESCRIPTION

[0013] Various embodiments are described and illustrated herein to provide an overall understanding of the disclosed titanium alloy plates and other articles and methods ofmaking titanium alloy plates and other articles. The various embodiments described and illustrated herein are non-limiting and non-exhaustive. Thus, the invention is not limited by the description of the various non-limiting and non-exhaustive embodiments disclosed herein.

[0014] The features and characteristics illustrated and / or described in connection with various embodiments herein may be combined with the features and characteristics of other embodiments. Such modifications and variations are intended to be included within the scope of this specification. As such, the claims may be amended to recite any features or characteristics expressly or inherently described in, or otherwise expressly or inherently supported by, this specification. Further, the applicant reserves the right to amend the claims to affirmatively disclaim features or characteristics that may be present in the prior art.

[0015] The various embodiments disclosed and described in this specification can comprise, consist of, or consist essentially of the features and characteristics as variously described herein. For example, reference herein to a titanium alloy “comprising” a particular elemental composition is intended to also encompass alloys “consisting essentially of” or “consisting of” the stated composition. It will be understood that titanium alloy compositions described herein that “comprise”, “consist of”, or “consist essentially of” a particular composition also may include impurities. Also, for example, reference herein to a titanium alloy plate or other article “comprising” particular elements and / or characteristics is intended to also encompass plates or articles “consisting essentially of” or “consisting of” the stated elements and / or characteristics.

[0016] All elemental concentrations provided herein for an alloy composition are weight percentages based on total weight of the particular alloy composition, unless otherwise indicated herein.

[0017] Dual hardness armor plate can be difficult and expensive to manufacture. For example, in producing conventional steel roll-bonded dual hardness armor plate, complex post roll-bonding heat treatments and other processing may be required to achieve desired mechanical and ballistic properties of the layers within the armor. Additionally, dual hardness steel armor can be relatively heavy and add significant weight to military and other vehicles, limiting acceptable armor thickness and achievable ballistic projectile penetration resistance.

[0018] Titanium is significantly less dense than steel and has comparable tensile and yield strengths. Accordingly, titanium armor can reduce the overall weight of an armor system while providing comparable ballistic projectile penetration resistance. Titanium armors havebeen available in the form of monolithic plates of CP titanium and certain titanium alloys. Certain dual-layer (i.e. , dual hardness) titanium armor plate products also are known.However, known dual hardness titanium armors have not been satisfactory replacements for monolayer CP titanium and monolayer titanium alloy armors. The present inventors have observed that an improvement in a dual hardness titanium armor against penetration by one type of ballistic projectile used in standardized ballistic testing of armor plate can occur at the expense of protection against penetration by a different type of ballistic projectile. For example, a modification improving penetration resistance of a dual hardness titanium armor against standard fragment simulating projectiles (FSP) used in ballistic testing can result in a decrease in penetration against standard armor piercing (AP) projectiles. Also, dual hardness titanium armors can be more difficult to manufacture than monolayer titanium armors.

[0019] Improved dual hardness titanium alloy armors and other titanium alloy articles, and methods of making the same, are provided herein. Embodiments of the titanium alloy plates and articles herein can provide enhanced ballistic projectile penetration performance and / or enhanced manufacturability. The improved ballistic projectile penetration resistance of the titanium alloy armor and other articles disclosed herein can allow for weight reduction and / or enhanced protection against ballistic projectile penetration in, for example, military vehicles and other military equipment.

[0020] Referring to FIG. 1, a non-limiting embodiment of a titanium alloy article 100 according to the present disclosure comprises a first layer 102 and a second layer 104. The first layer 102 and the second layer 104 are metallurgically bonded together, and a metallurgical bond region 106 is present between the first layer 102 and the second layer 104. The first layer 102 and the second layer 104 differ in at least one measurable mechanical property. In certain embodiments, the titanium alloy article 100 may be a titanium alloy armor plate comprising the first layer 102 metallurgically bonded to the second layer 104 and including the metallurgical bond region 106. In various non-limiting embodiments, the titanium alloy article 100 can comprise an additional layer or at least two additional layers.

[0021] The first layer 102 can comprise an exposed surface 102a of the titanium alloy article 100. In embodiments in which the titanium alloy article 100 is an armor plate, for example, the exposed surface 102a can be a "strike face" that would be contacted initially by a ballistic projectile striking the plate. For example, the surface 102a can be oriented in a direction from which a ballistic projectile may originate. The first layer 102 has one or more mechanical properties suitable to flatten and / or fragment an incoming ballistic projectilestriking the exposed surface 102a of the first layer 102. The second layer 104 has one or more mechanical properties suitable to inhibit or prevent deformed projectiles and / or projectile fragments that pass through the first layer 102 from passing through the second layer 104. For example, mechanical properties of the second layer 104 are controlled so that the second layer 104 absorbs the energy of deformed projectiles and / or fragments passing through the first layer 102 and inhibits spalling of the surface 104a of the second layer 104. Providing a first layer 102 with mechanical properties promoting flattening and / or fragmenting a ballistic projectile and a second layer 104 with mechanical properties inhibiting penetration of the projectile material reaching the second layer 104 results in a multi-layer titanium alloy material particularly suited for use as a ballistic armor plate.

[0022] While not being bound to any particular theory, the present inventors believe that adiabatic shearing is a significant factor in the deformation and failure of a titanium alloy article impacted by a high energy ballistic projectile or projectile fragment. The present inventors believe that enhancing the resistance of the second layer 104 to deformation by adiabatic shear can enhance the overall ballistic projectile penetration resistance of the titanium alloy article 100. For example, the second layer 104 can resist strain localization and receive more damage.

[0023] The mechanical property differing between the first layer 102 and the second layer 104 can be hardness, toughness, or another mechanical property. For example, in certain embodiments, hardness of the first layer 102 and the second layer 104 differs. In certain other embodiments, toughness of the first layer 102 and the second layer 104 differs. In various embodiments, more than one mechanical property of the first layer 102 and the second layer 104 differ. For example, in certain embodiments, both the hardness and toughness of the first layer 102 differ from the second layer 104 in the titanium alloy article 100.

[0024] Hardness of a titanium alloy plate or other article may be measured as a Brinell hardness (HBW). As reported herein, the Brinell hardness values were measured according to the procedure of ASTM E10-18, “Standard Test Method for Brinell Hardness of Metallic Materials.” In the present disclosure, HBW values were measured in units of kgf / mm2and, as is conventional, are reported herein as unitless values. In various embodiments of a titanium alloy plate or other article according to the present disclosure, the first layer has a first Brinell hardness, the second layer has a second Brinell hardness, and the first and second Brinell hardnesses differ. In various non-limiting embodiments, the first hardness can be 10 to 100 HBW greater than the second hardness, such as, for example, 10 to 80 HBW, 10 to 60 HBW, 20 to 60 HBW, 25 to 60 HBW, 20 to 50 HBW, or 20 to 40 HBW greaterthan the second hardness. In various non-limiting embodiments, the first hardness can be in a range of 300 to 400 HBW, such as, for example, 300 to 380 HBW, 310 to 370 HBW, 320 to 370 HBW, 330 to 370 HBW, 340 to 370 HBW, or 340 to 360 HBW. In certain non-limiting embodiments, the second hardness can be in a range of 250 to 370 HBW, such as, for example, 280 to 370 HBW, 280 to 350 HBW, 290 to 350 HBW, 280 to 340 HBW, 280 to 330 HBW, 280 to 320 HBW, or 290 to 320 HBW.

[0025] Selecting the desired hardness of the first layer 102 and of the second layer 104 can involve balancing the ability to fragment ballistic projectiles upon impact and resist fracturing of the titanium alloy and / enhance manufacturability. For example, providing first and second layers 102, 104 having a large difference in hardness may provide desired ballistic projectile penetration resistance but limit the ability to form the metallurgical bond or may otherwise make production of the multi-layer titanium alloy article 100 difficult. Similarly, providing a small difference in hardnesses between the first and second layers 102, 104 can enhance manufacturability but may not result in desired ballistic projectile penetration resistance. In various non-limiting embodiments, the first hardness may be a greater than a threshold hardness suitable to break up and flatten an incoming projectile contacting the first layer.

[0026] Toughness of a titanium alloy can be related to a combination of the strength and elongation of the titanium alloy. For example, a material with a higher toughness can have a high strength and a high elongation. In certain embodiments of the titanium alloy article 100, the first layer 102 has a first toughness, the second layer 104 has a second toughness, and the second toughness is greater than the first toughness. In certain embodiments of a titanium armor plate or other article according to the present disclosure, the second toughness of the second layer 104 can be greater than the first toughness of the first layer 102.

[0027] Selecting the desired toughness of the first and second layers 102, 104 can involve balancing ballistic projectile penetration resistance and manufacturability. For example, providing first and / or second layers having high toughness can impair the ability to form the metallurgical bond 106 between the first and second layers 102, 104 or otherwise make production of the multi-layer armor or other article difficult, while providing low toughness in one or both of the first and second layers 102, 104 can enhance manufacturability but may result in undesirably low ballistic projectile penetration resistance. In various non-limiting embodiments, the second toughness may be greater than a threshold toughness suitable to absorb the energy of and capture a deformed projectile and / or fragments of a projectile passing through the first layer 102 and prevent penetration through the second layer 104 of the multi-layer titanium alloy article 100.

[0028] In various embodiments the first titanium alloy can comprise an elongation in a range of 8% to 20%, such as, for example, 10% to 20%, 8% to 18%, 10% to 18%, 12% to 20%, 12% to 16%, 13% to 16%, 14% to 16%, or 13% to 15%. The second titanium alloy can comprise an elongation in a range of 10% to 20%, such as, for example, 10% to 18%, 12% to 18%, 13% to 18%, 13% to 17%, 14% to 16%, or 14% to 16%. Elongation can be measured according to ASTM E8 / E8M-13a.

[0029] Selecting the desired elongation of the first and second layers 102, 104 can involve balancing the ability to fragment ballistic projectiles upon impact and resist fracturing of the titanium alloy and / enhance manufacturability. For example, increasing elongation of a titanium alloy can enhance the overall ballistic projectile penetration resistance of the titanium alloy. Having too high of a hardness for a titanium alloy can detrimentally impact the elongation of the titanium alloy, which can lead to fractures in the titanium alloy upon impact of a ballistic projectile. In certain non-limiting embodiments, the elongation of the first layer 104 may be greater than a threshold elongation suitable to resist fracturing of the first layer 102. In various non-limiting embodiments, the elongation of the second layer 104 may be greater than a threshold elongation suitable to absorb the energy of and capture a deformed projectile and / or fragments of a projectile passing through the first layer 102 and prevent penetration through the second layer 104 of the multi-layer titanium alloy article 100.

[0030] In certain embodiments, the first titanium alloy can comprise a longitudinal yield strength in a range of 135 to 160 kilopounds force per square inch (ksi), such as, for example, 140 to 160 ksi, 142 to 148 ksi, or 142 to 146 ksi. In certain embodiments, the second titanium alloy can comprise a longitudinal yield strength in a range of 105 to 140 ksi, such as, for example, 110 to 135 ksi, 112 ksi to 130 ksi, 110 ksi to 120 ksi, or 125 ksi to 135 ksi. Longitudinal yield strength can be measured according to ASTM E8 / E8M-13a.

[0031] In various embodiments, the first titanium alloy can comprise a longitudinal ultimate tensile strength in a range of 150 to 175 ksi, such as, for example, 155 to 175 ksi, 155 to 165 ksi, or 157 to 162 ksi. In certain embodiments, the second titanium alloy can comprise a longitudinal ultimate tensile strength in a range of 120 to 160 ksi, such as, for example, 125 to 150 ksi, 130 to 150 ksi, 125 to 135 ksi, or 140 to 150 ksi. Longitudinal ultimate tensile strength can be measured according to ASTM E8 / E8M-13a.

[0032] While not being bound to any particular theory, the present inventors believe providing titanium alloys in the first and second layers having similar chemistries and / or certain mechanical properties that do not significantly differ can enhance ballistic performance and / or manufacturability of the titanium alloy article.

[0033] In certain non-limiting embodiments, the first titanium alloy can be an alpha-beta titanium alloy. In various non-limiting embodiments, the second titanium alloy can be an alpha-beta titanium alloy.

[0034] Various mechanical properties of the first and second layer 102, 104 can be provided to enhance manufacturability of the multi-layer titanium armor or other article.

[0035] In certain non-limiting embodiments, the first titanium alloy in the first layer of a titanium alloy armor plate or other article according to the present disclosure can be an alpha-beta titanium alloy comprising, in weight percent based on total weight of the titanium alloy: 2.0 to 7.0 aluminum; at least 2.1 vanadium; a molybdenum equivalency in the range of 2.0 to 5.0; 0.1 to 4.0 cobalt; 0 to 0.5 oxygen; 0 to 0.25 nitrogen; 0 to 0.3 carbon; incidental impurities; and titanium. In certain non-limiting embodiments, the first titanium alloy is an alpha-beta titanium alloy comprising, in weight percent based on total weight of the titanium alloy: 2.0 to 7.0 aluminum; at least 2.1 vanadium; a molybdenum equivalency in the range of 2.0 to 5.0; 0.1 to 4.0 cobalt; 0 to 0.5 oxygen; 0 to 0.25 nitrogen; 0 to 0.3 carbon; 0 to 6 tin; 0 to 0.6 silicon; 0 to 10 zirconium; 0 to 0.3 palladium; 0 to 0.5 boron; 0 up to 0.3 total weight percent of one or more of cerium, praseodymium, neodymium, samarium, gadolinium, holmium, erbium, thulium, yttrium, scandium, and beryllium; 0 up to 0.5 total weight percent of one or more of gold, silver, palladium, platinum, nickel, and iridium; 0 to 0.015 hydrogen; incidental impurities; and titanium. In certain non-limiting embodiments, the first titanium alloy is an alpha-beta titanium alloy comprising, in weight percent based on total weight of the titanium alloy: 4.75 to 5.25 aluminum; 2.25 to 2.75 vanadium; 0.8 to 1.20 cobalt; 0 to 0.25 nitrogen; 0 to 0.02 carbon; 3.8 to 4.2 tin; 0.6 to 1 iron; 0 to 0.25 oxygen; incidental impurities; and titanium. A commercially available titanium alloy having the foregoing chemistries is TITAN 27™ alloy, available from ATI Inc., Dallas, TX, USA.

[0036] The molybdenum equivalency of an alloy is a concept used to quantify the overall beta-stabilizing effect of the different alloying elements in a titanium alloy. As referred to in the present disclosure, molybdenum equivalency quantifies an alloy’s molybdenum and equivalent weight percentage of molybdenum embodied in other alloying additions, and it is calculated by the following equation, in which the content of each beta phase stabilizer element listed in the equation is in weight percent:[Mo]eq= [Mo] + 2 / 3[V] + 3[Mn + Fe + Ni + Cr + Cu + Be] + 1 / 3[Ta + Nb + W],

[0037] In certain non-limiting embodiments, the second titanium alloy in the second layer of a titanium alloy armor plate or other article according to the present disclosure can be an alpha-beta titanium alloy comprising, in weight percent based on total weight of the titaniumalloy: 2.0 to 7.0 aluminum; at least 2.1 vanadium; a molybdenum equivalency in the range of 2.0 to 5.0; 0.1 to 4.0 cobalt; 0 to 0.5 oxygen; 0 to 0.25 nitrogen; 0 to 0.3 carbon; incidental impurities; and titanium. In certain non-limiting embodiments, the second titanium alloy is an alpha-beta titanium alloy comprising, in weight percent based on total weight of the titanium alloy: 2.0 to 7.0 aluminum; at least 2.1 vanadium; a molybdenum equivalency in the range of 2.0 to 5.0; 0.1 to 4.0 cobalt; 0 to 0.5 oxygen; 0 to 0.25 nitrogen; 0 to 0.3 carbon; 0 to 6 tin; 0 to 0.6 silicon; 0 to 10 zirconium; 0 to 0.3 palladium; 0 to 0.5 boron; 0 up to 0.3 total weight percent of one or more of cerium, praseodymium, neodymium, samarium, gadolinium, holmium, erbium, thulium, yttrium, scandium, and beryllium; 0 up to 0.5 total weight percent of one or more of gold, silver, palladium, platinum, nickel, and iridium; 0 to 0.015 hydrogen; incidental impurities; and titanium. In certain non-limiting embodiments, the second titanium alloy is an alpha-beta titanium alloy comprising, in weight percent based on total weight of the titanium alloy: 3.6 to 4.1 aluminum; 2.25 to 2.75 vanadium; 1 to 1.4 cobalt; 0 to 0.25 nitrogen; 0 to 0.02 carbon; 2.5 to 2.9 tin; 0.35 to 0.65 iron; 0 to 0.25 oxygen; 0 to 0.015 hydrogen; incidental impurities; and titanium.

[0038] In certain non-limiting embodiments, the second titanium alloy in the second layer of a titanium alloy armor plate or other article according to the present disclosure is an alphabeta titanium alloy comprising, in weight percent based on total weight of the titanium alloy: 3.5 to 4.5 aluminum; 2.0 to 3.0 vanadium; 1.2 to 1.8 iron; 0 to 0.3 oxygen; 0 to 0.03 nitrogen; 0 to 0.08 carbon; 0 to 0.015 hydrogen; incidental impurities; and titanium. In certain nonlimiting embodiments, the second titanium alloy is an alpha-beta titanium alloy comprising, in weight percent based on total weight of the titanium alloy: 3.5 to 4.5 aluminum; 2.0 to 3.0 vanadium; 0 to 0.05 nitrogen; 0 to 0.08 carbon; 1.2 to 1.8 iron; 0 to 0.3 oxygen; 0 to 0.015 hydrogen; incidental impurities; and titanium. In certain non-limiting embodiments, the second titanium alloy is an alpha-beta titanium alloy comprising, in weight percent based on total weight of the titanium alloy: 3.7 to 4.3 aluminum; 2.2 to 2.8 vanadium; 0 to 0.05 nitrogen; 0 to 0.08 carbon; 1.2 to 1.8 iron; 0 to 0.3 oxygen; 0 to 0.015 hydrogen; incidental impurities; and titanium. A commercially available titanium alloy having the foregoing chemistry is ATI 425® alloy, available from ATI Inc. Dallas, TX, USA. A titanium alloy having the foregoing chemistry is the alloy specified in UNS R54250.

[0039] In certain non-limiting embodiments, the second titanium alloy in the second layer of a titanium alloy armor plate or other article according to the present disclosure is an alphabeta titanium alloy comprising, in weight percent based on total weight of the titanium alloy: 5.5 to 6.75 aluminum; 3.5 to 4.5 vanadium; 0 to 0.4 iron; 0 to 0.2 oxygen; 0 to 0.05 nitrogen; 0 to 0.08 carbon; 0 to 0.015 hydrogen; incidental impurities; and titanium. A commerciallyavailable titanium alloy having the foregoing chemistry is ATI 6-4™ alloy, available from ATI Inc., Dallas, TX, USA. A titanium alloy having the foregoing chemistry is the alloy specified in UNS R56400.

[0040] In certain non-limiting embodiments, the second titanium alloy in the second layer of a titanium alloy armor plate or other article according to the present disclosure is an alphabeta titanium alloy comprising, in weight percent based on total weight of the titanium alloy: 5.5 to 6.5 aluminum; 3.5 to 4.5 vanadium; 0 to 0.25 iron; 0 to 0.13 oxygen; 0 to 0.03 nitrogen; 0 to 0.08 carbon; 0 to 0.0125 hydrogen; incidental impurities; and titanium. A commercially available titanium alloy having the foregoing chemistry is ATI 6-4 ELI™ alloy, available from ATI Inc., Dallas, TX, USA. A titanium alloy having the foregoing chemistry is the alloy specified in UNS R56407.

[0041] Titanium alloys included in titanium alloy articles according to the present disclosure may include incidental impurities. Incidental impurities may be present in the alloys as a result of, for example, impurities in starting materials (e.g., recycled scrap materials) and / or impurities introduced into the alloy by processing during alloy production. In various nonlimiting embodiments of titanium alloys included in titanium alloy articles according to the present disclosure, one or more of the following elements may be present as impurities: sulfur, phosphorus, calcium, oxygen, nitrogen, bismuth, lead, tin, antimony, selenium, arsenic, silver, tellurium, thallium, zinc, ruthenium, platinum, rhodium, palladium, osmium, iridium, gold, fluorine, and chlorine. Impurity elements, if present, typically are present in individual concentrations no greater than about 0.1 weight percent, and the total content of such impurities typically is no greater than 5.0 weight percent. It will be understood that the foregoing list of impurity elements is not necessarily inclusive of all elements that might be present as impurities in a titanium alloy included in a titanium alloy article according to the present disclosure.

[0042] Again referring to FIG. 1, the first layer 102 of the titanium alloy article 100 can comprise a thickness, ti , and the second layer 104 of the titanium alloy article 100 can comprise a thickness, t2. The thickness, ti, and the thickness, t2, can be selected to enhance ballistic projectile penetration performance of the titanium alloy article 100. For example, in certain embodiments of a titanium alloy article according to the present disclosure a ratio of the thickness, ti, to the thickness, t2, can be in a range of 25:75 to 75:25, such as, for example, 30:70 to 70:30 or 50:50 to 70:30. In various embodiments, the sum of the thickness, ti, and the thickness, t2, can correspond to the overall thickness of the titanium alloy article 100 and can be in a range of 0.040 inch (0.102 cm) to 4 inches (10.16 cm), or greater.

[0043] The first layer 102 and the second layer 104 are metallurgical^ bonded together. The metallurgical bond attaches at least a region of the first layer 102 with at least a region of the second layer 104 along an interfacial region. The metallurgical bond between the first layer 102 and the second layer 104 can be formed using any suitable process that will form a secure metallurgical bond between alloys used to form the two layers 102, 104. In certain non-limiting embodiments of a method for making a titanium alloy armor plate or other titanium alloy article according to the present disclosure, a plate of the first titanium alloy and a plate of the second titanium alloy are stacked together to form an assembly that is hot rolled to metallurgically bond the plates together. The hot rolling process results in formation of a metallurgical bond region 106 in which the first layer 102 comprising the first titanium alloy as taught herein is inter-diffused with the second layer 104 comprising a second titanium alloy as taught herein, thereby securing the layers together. The multi-layer structure resulting from the metallurgical bonding of plates of a first titanium alloy and a second titanium alloy as taught herein can synergistically enhance ballistic projectile penetration resistance of the titanium alloy article 100.

[0044] A titanium alloy article according to the present disclosure can provide substantial ballistic projectile penetration resistance. A conventional technique to assess ballistic projectile penetration performance of an armor plate or other article is to determine a Vsofor the plate. The V50 is the velocity at which 50% of the particular standardized projectiles fired at the article are expected to penetrate the article. Accordingly, a higher V50 indicates greater ballistic projectile penetration resistance for the particular ballistic projectile used in the testing. The V50 can be measured according to the U.S. Department of Defense MIL-STD-662E standard. For example, the V50 can be measured as follows. The plate or other article being evaluated is positioned at a normal (0 degree) angle to the projectile's path of flight; multiple projectiles are fired at the article; the striking velocities of the projectiles are measured using orthogonal flash radiographs; complete penetration (CP) is determined either by using a witness plate behind the target or by analyzing residual x-rays to detect if any material broke through; and the V50 ballistic limit is then calculated according to the U.S. Department of Defense MIL-STD-662E standard. The V50 can be calculated by averaging the velocities of an equal number of the highest partial penetrations and the lowest complete penetrations.

[0045] Embodiments of a titanium alloy plate or other article according to the present disclosure can exhibit an average V50 when tested with 0.50 caliber AP M2 projectiles that is at least 130 feet / second (fps) greater than required by U.S. Department of Defense MIL-DTL-46077E standard, such as, for example, at least 140 fps, at least 150 fps, at least 160fps, or at least 165 fps greater than required by U.S. Department of Defense MIL-DTL-46077E standard. When tested with 0.50 caliber AP M2 projectiles, embodiments of a titanium alloy plate or other article according to the present disclosure can comprise an average V5o in a range of 130 to 200 fps greater than required by U.S. Department of Defense MIL-DTL-46077E standard, such as, for example, 140 to 190 fps, 150 to 190 fps, 160 to 180 fps, or fps to 180 fps greater than required by U.S. Department of Defense MIL-DTL-46077E standard.

[0046] Embodiments of a titanium alloy plate or other article according to the present disclosure can exhibit an average V5o when tested with 20 mm FSP projectiles at least 200 fps greater than required by U.S. Department of Defense MIL-DTL-46077G standard, such as, for example, at least 220 fps, at least 240 fps, at least 250 fps, at least 260 fps, or at least 280 fps greater than required by U.S. Department of Defense MIL-DTL-46077G standard. When tested with 20 mm FSP projectiles, embodiments of a titanium alloy plate or other article according to the present disclosure can exhibit an average V50 in a range of 200 to 350 fps greater than required by U.S. Department of Defense MIL-DTL-46077G standard, such as, for example, 220 to 350 fps, 250 to 350 fps, 260 to 320 fps, or 280 to 320 fps greater than required by U.S. Department of Defense MIL-DTL-46077G standard.

[0047] Unless otherwise indicated, an “average V50” as used herein is a mean of the V50 of typical test samples. In certain non-limiting embodiments, the average V50 may be calculated when using plate samples with a 1 inch thickness.

[0048] Embodiments of a titanium alloy article according to the present disclosure can exhibit substantial ballistic projectile penetration resistance while having low mass per unit volume. For example, embodiments of a titanium alloy article according to the present disclosure can exhibit a mass efficiency, Em, of at least 1.38 when tested with 0.50 caliber AP M2 projectiles. Also, for example, embodiments of a titanium alloy article according to the present disclosure can exhibit a mass efficiency, Em, of at least 1.37 when tested with 20 mm FSP projectiles. In various non-limiting embodiments, the titanium alloy article according to the present disclosure can exhibit an Emat least 5% greater than an Emof a homogeneous monolayer of a titanium alloy as measured with at least two different ballistic projectiles (e.g., 0.50 caliber AP M2 projectiles and 20 mm FSP projectiles), such as, for example, at least 6% greater, at least 7% greater, or at least 8% greater than an Emof a homogeneous monolayer of a titanium alloy as measured with at least two different ballistic projectiles.

[0049] Mass efficiency, Em, is a dimensionless ratio that can define the reduction in weight that can be achieved while maintaining the same level of protection as rolled homogenous armor (RHA) steel. The mass efficiency, Em, can be used to evaluate the ballistic performance of articles relative to their weight. Higher mass efficiency values can indicate enhanced performance-to-weight ratios, which can be desirable for applications where weight reduction is desired. For example, a mass efficiency, Em, of 2.0 would indicate the article provides the same protection as RHA steel at half the weight.

[0050] Mass efficiency, Em, of an article is defined in equation 1 :Equation 1Areal Density of RHA steelMAreal Density of Article

[0051] Areal density is the weight per unit area of the armor which can be measured in kg / m2, lb / ft2, or other unit. The areal density is defined at a configuration of the RHA steel and the Sample where they provide the same level of protection against the same specific ballistic projectile. RHA steel can be made according to military standard MIL-DTL-12560. One of ordinary skill in the art would understand how to produce and / or measure an article against RHA steel.

[0052] A titanium alloy article according to the present disclosure, for example, titanium alloy article 100, can be utilized in various applications. For example, and without limitation, the titanium alloy article can be in the form of a ballistic projectile penetration resistant armor plate or as all or a part of a blast-protective hull, a blast-protective V-shaped hull, a blast-protective vehicle underbelly, or a blast-protective enclosure.

[0053] Referring to FIG. 3, the present disclosure also provides a method of manufacturing a titanium alloy plate or other article. The method can comprise disposing a first part comprising a first titanium alloy on a second part comprising a second titanium alloy so that at least a portion of the first titanium alloy part contacts the second titanium alloy part to thereby form an assembly, 302. In certain embodiments, the first and second parts can be in the form of, respectively, a first plate consisting of the first titanium alloy and a second plate consisting of the second titanium alloy. The first part has a first value of a mechanical property and the second part has a second value of the mechanical property. The first value of the first part differs from the second value of the second part, and the difference enhances manufacturability and / or ballistic projectile penetration resistance of a multi-layer titanium alloy article formed from the assembly.

[0054] Again referring to FIG. 3, the method can comprise metallurgical^ bonding the first part to the second part to thereby form a metallurgically bonded part, 304. For example, metallurgically bonding can comprise securing the first part to the second part to form a secured assembly. The parts may be secured together by, for example, welding (e.g., MIG, TIG, electron beam welding, or friction stir welding) the parts together around a periphery of the assembly at the point where the parts meet, to provide a secured assembly. The secured assembly can be processed to form a metallurgical bond between the first part and the second part. In certain embodiments the secured assembly can be hot rolled to form the metallurgical bond between the first and second parts. Hot rolling can comprise reducing a thickness of the secured assembly to a thickness suitable for an armor or other intended application. Hot rolling the secured assembly can comprise rolling at a temperature in a range that is at least 1000°F (538°C) and up to a beta transus temperature of the first part or second part. The hot rolled assembly can be mill annealed and an alpha-beta structure (e.g., contain bimodal structure) can be formed.

[0055] In certain non-limiting embodiments, prior to step 302, it may be desirable to prepare the contacting surfaces of the first and second titanium alloy parts by, for example, machining and / or grinding all or a portion of one or both of the contacting surfaces.

[0056] EXAMPLES

[0057] The following examples are intended to further describe certain non-limiting embodiments, without restricting the scope of the present invention. Persons having ordinary skill in the art will appreciate that variations of the following examples are possible within the scope of the invention.

[0058] One-inch thick monolayer plates of four alloys, identified as Alloys A-D, were tested for longitudinal and transverse mechanical properties. Alloys A and B are grades of ATI® TITAN 27™ alloy, Alloy C is a grade of ATI 425® alloy (UNS R54250), and Alloy D is ATI® Ti-64 alloy (UNS R56400). All of these alloys are commercially available from ATI Inc., Dallas, TX, USA). Alloy A comprised, in weight percentages based on total alloy weight: 4.75 to 5.25 aluminum; 2.25 to 2.75 vanadium; 0.8 to 1.20 cobalt; 0 to 0.25 nitrogen; 0 to 0.02 carbon; 3.8 to 4.2 tin; 0.6 to 1 iron; 0 to 0.25 oxygen; incidental impurities; and titanium. Alloy B comprised, in weight percentages based on total alloy weight: 3.6 to 4.1 aluminum; 2.25 to 2.75 vanadium; 1 to 1.4 cobalt; 0 to 0.25 nitrogen; 0 to 0.02 carbon; 2.5 to 2.9 tin; 0.35 to 0.65 iron; 0 to 0.25 oxygen; 0 to 0.015 hydrogen; incidental impurities; and titanium. Alloy C comprised, in weight percentages based on total alloy weight: 3.7 to 4.3 aluminum; 2.2 to 2.8 vanadium; 0 to 0.05 nitrogen; 0 to 0.08 carbon; 1.2 to 1.8 iron; 0 to 0.3 oxygen; 0to 0.015 hydrogen; incidental impurities; and titanium. Alloy D comprised, in weight percentages based on total alloy weight: 5.5 to 6.75 aluminum; 3.5 to 4.5 vanadium; 0 to 0.4 iron; 0 to 0.2 oxygen; 0 to 0.05 nitrogen; 0 to 0.08 carbon; 0 to 0.015 hydrogen; incidental impurities; and titanium.

[0059] Mechanical test results of the monolayer plates of the four alloys are shown in Table 1 below.Table 1 - Mechanical Properties of Monolayer PlatesYield Ultimate UltimateTensile Elongation Yield Strength, Tensile Elongation, Hardness Alloy Strength,(longitudinal) Strength (longitudinal) (transverse) Strength(trans (transverse) (HBW) (ksi) (longitudinal) (%) (ksi) verse) (%)(ksi) (ksi)Titan-27 A(Alloy A) 144 159 13 154 168 14 350 Titan-27 B(Alloy B) 128 146 14 138 153 15 320 425 Alloy(Alloy C) 113 132 14 124 140 15 300 Ti-64 Alloy 130 145 13 135 149 13 310(Alloy D)

[0060] Two multi-layer titanium alloy plates, referenced in this example as Article 1 and Article 2, were prepared from combinations of the monolayer plates and alloys identified in Tables 1 and 2. Article 1 comprised a first layer of Alloy A metallurgically bonded to a second layer of Alloy C by hot rolling. Article 2 comprised a first layer of Alloy A metallurgically bonded to a second layer of Alloy B by hot rolling. After hot rolling, each article was mill-annealed.

[0061] An ultrasonic transducer probe was used to confirm that the plates had metallurgically bonded together, forming dual layers in each article. The articles were annealed and pickled. Articles 1 and 2 and monolayer plates of Alloys A-D were subjected to ballistic testing to determine V50 and Emvalues, and the results are provided in Table 3 below:Table 3 - Ballistic Test ResultsArticle V500.50 inch EM 0.50 V5020 mm FSP Em20 mm FSP AP M2 (fps inch AP (fps greatergreater than M2 thanrequirement) requirement)Article 1 169 1.41 298 1.39Article 2 151 1.39 156 1.32Alloy A 122 1.37 58 1.26Alloy B 53 1.30 189 1.34Alloy C 78 1.33 119 1.36Alloy D | 62 1.31 120 1.33

[0062] Referring to Table 3, Articles 1 and 2 exhibited significant improvements in V50 and mass efficiency over the monolayer plates of Alloys A-D as tested with 0.5 inch AP M2 rounds. Article 1 also exhibited significant improvements in V50 and mass efficiency over the monolayer plates of Alloys A-D as tested with 20 MM FSP rounds. The V50 and mass efficiency results in Table 3 for Article 1 are consistently better than for Article 2. The ballistic test results in Table 3 show that the multilayer titanium alloy articles produced in this example can provide substantially improved ballistic projectile penetration resistance.

[0063] It will be understood that the scope of the present disclosure is not necessarily limited to alloys comprising the elemental contents listed in the Examples. It is believed that other titanium alloy articles according to the present disclosure can exhibit synergistic performance against ballistic projectiles.

[0064] The following numbered clauses are directed to various non-limiting embodiments according to the present disclosure:

[0065] Clause 1. A titanium alloy article comprising: a first layer comprising a first titanium alloy having a first hardness; a second layer comprising a second titanium alloy having a second hardness, wherein the first hardness is 10 HBWto 100 HBW greater than the second hardness; and a metallurgical bond between the first layer and the second layer.

[0066] Clause 2. A titanium alloy article comprising: a first layer comprising a first titanium alloy having a first hardness in a range of 300 HBW to 400 HBW; a second layer comprising a second titanium alloy having a second hardness in a range of 250 HBWto 370 HBW, wherein the second hardness is less than the first hardness; and a metallurgical bond between the first titanium alloy and the second titanium alloy.

[0067] Clause 3. A titanium alloy article, comprising: a first layer comprising a first titanium alloy; a second layer comprising a second titanium alloy ;and a metallurgical bond between the first titanium alloy and the second titanium alloy, wherein the titanium alloy article exhibits at least one of the following: an Em of at least 1.38 when tested with 0.50 caliber AP M2; an Em of at least 1.37 when tested with 20 mm fragment simulating projectile; and an Em at least 5% greater than an Em of a homogeneous monolayer of a titanium alloy as measured with at least two different ballistic projectiles.

[0068] Clause 4. The titanium alloy article of any of clauses 1-3, wherein the first titanium alloy has an elongation in a range of 8% to 20%.

[0069] Clause 5. The titanium alloy article of any of clauses 1-4, wherein the second titanium alloy has an elongation in a range of 10% to 20%.

[0070] Clause 6. The titanium alloy article of any of clauses 1-5, wherein the first titanium alloy has an elongation in a range of 13% to 15% and the second titanium alloy has an elongation in a range of 14% to 16%.

[0071] Clause 7. The titanium alloy article of any of clauses 1-6, wherein the first titanium alloy has a first hardness in a range of 300 HBW to 380 HBW.

[0072] Clause 8. The titanium alloy article of any of clauses 1-7, wherein the second titanium alloy has a second hardness in a range of 280 HBW to 370 HBW.

[0073] Clause 9. The titanium alloy article of any of clauses 1-8, wherein the titanium alloy article exhibits an Em of at least 1.38 when tested with 0.50 caliber AP M2.

[0074] Clause 10. The titanium alloy article of any of clauses 1-9, wherein the titanium alloy article exhibits an Em of at least 1.37 when tested with 20 mm fragment simulating projectile.

[0075] Clause 11. The titanium alloy article of any of clauses 1-10, wherein the first layer comprises a first thickness and the second layer comprises a second thickness, wherein a ratio of the first thickness to the second thickness is in a range of 25:75 to 75:25.

[0076] Clause 12. The titanium alloy article of any of clauses 1-11 , wherein the first titanium alloy has a longitudinal yield strength in a range of 135 ksi to 160 ksi.

[0077] Clause 13. The titanium alloy article of any of clauses 1-12, wherein the second titanium alloy has a longitudinal yield strength in a range of 105 ksi to 140 ksi.

[0078] Clause 14. The titanium alloy article of any of clauses 1-13, wherein the first titanium alloy has a longitudinal ultimate tensile strength in a range of 150 ksi to 175 ksi.

[0079] Clause 15. The titanium alloy article of any of clauses 1-14, wherein the second titanium alloy has a longitudinal ultimate tensile strength in a range of 120 ksi to 160 ksi.

[0080] Clause 16. The titanium alloy article of any of clauses 1-15, wherein the first titanium alloy is an alpha-beta titanium alloy comprising, in weight percentages: 2.0 to 7.0 aluminum; at least 2.1 vanadium; a molybdenum equivalency in a range of 2.0 to 5.0; 0.1 to 4.0 cobalt; up to 0.5 oxygen; up to 0.25 nitrogen; up to 0.3 carbon; incidental impurities; and titanium.

[0081] Clause 17. The titanium alloy article of any of clauses 1-16, wherein the second titanium alloy is an alpha-beta titanium alloy comprising, in weight percentages: 2.0 to 7.0 aluminum; at least 2.1 vanadium; a molybdenum equivalency in a range of 2.0 to 5.0; 0.1 to4.0 cobalt; up to 0.5 oxygen; up to 0.25 nitrogen; up to 0.3 carbon; incidental impurities; and titanium.

[0082] Clause 18. The titanium alloy article of any of clauses 1-16, wherein the second titanium alloy is an alpha-beta titanium alloy comprising, in weight percentages: 3.5 to 4.5 aluminum; 2.0 to 3.0 vanadium; 1.2 to 1.8 iron; up to 0.3 oxygen; up to 0.03 nitrogen; up to 0.08 carbon; up to 0.015 hydrogen; incidental impurities; and titanium.

[0083] Clause 19. The titanium alloy article of any of clauses 1-18, wherein the titanium alloy article comprises an armor, a blast-protective hull, a blast-protective V-shaped hull, a blast-protective vehicle underbelly, a blast-protective enclosure, or a combination thereof.

[0084] Clause 20. A titanium alloy article comprising: a first layer comprising a first titanium alloy; a second layer comprising a second titanium alloy; and a metallurgical bond between the first layer and the second layer, wherein the first titanium alloy is an alpha-beta titanium alloy comprising, in weight percentages: 2.0 to 7.0 aluminum; at least 2.1 vanadium; a molybdenum equivalency in a range of 2.0 to 5.0; 0.1 to 4.0 cobalt; up to 0.5 oxygen; up to 0.25 nitrogen; up to 0.3 carbon; incidental impurities; and titanium.

[0085] Clause 21. A titanium alloy article comprising: a first layer comprising a first titanium alloy; a second layer comprising a second titanium alloy; and a metallurgical bond between the first layer and the second layer, wherein the first titanium alloy is an alpha-beta titanium alloy comprising, in weight percentages: 4.75 to 5.25 aluminum; 2.25 to 2.75 vanadium; 3.8 to 4.2 tin; 0.8 to 1.2 cobalt; up to 0.25 oxygen; up to 0.25 nitrogen; up to 0.02 carbon; 0.6 to 1 iron; incidental impurities; and titanium.

[0086] Clause 22. The titanium alloy article of clause 20 or claim 21, wherein the second titanium alloy is an alpha-beta titanium alloy comprising, in weight percentages: 2.0 to 7.0 aluminum; at least 2.1 vanadium; a molybdenum equivalency in a range of 2.0 to 5.0; 0.1 to 4.0 cobalt; up to 0.5 oxygen; up to 0.25 nitrogen; up to 0.3 carbon; incidental impurities; and titanium.

[0087] Clause 23. The titanium alloy article of clause 20 or claim 21, wherein the second titanium alloy is an alpha-beta titanium alloy comprising, in weight percentages: 4.75 to 5.25 aluminum; 2.25 to 2.75 vanadium; 3.8 to 4.2 tin; 0.8 to 1.2 cobalt; up to 0.25 oxygen; up to 0.25 nitrogen; up to 0.02 carbon; 0.6 to 1 iron; incidental impurities; and titanium.

[0088] Clause 24. The titanium alloy article of clause 20 or claim 21, wherein the second titanium alloy is an alpha-beta titanium alloy comprising, in weight percentages: 3.6 to 4.1 aluminum; 2.25 to 2.75 vanadium; 2.5 to 2.9 tin; 1 to 1.4 cobalt; 0.35 to 0.65 iron; up to 0.25oxygen; up to 0.25 nitrogen; up to 0.02 carbon; up to 0.015 hydrogen; incidental impurities; and titanium.

[0089] Clause 25. The titanium alloy article of clause 20 or claim 21, wherein the second titanium alloy is an alpha-beta titanium alloy comprising, in weight percentages: 3.5 to 4.5 aluminum; 2.0 to 3.0 vanadium; 1.2 to 1.8 iron; up to 0.3 oxygen; up to 0.05 nitrogen; up to 0.08 carbon; up to 0.015 hydrogen; incidental impurities; and titanium.

[0090] Clause 26. The titanium alloy article of clause 20 or claim 21, wherein the second titanium alloy is an alpha-beta titanium alloy comprising, in weight percentages: 5.5 to 6.75 aluminum; 3.5 to 4.5 vanadium; 0 to 0.4 iron; up to 0.2 oxygen; up to 0.05 nitrogen; up to 0.08 carbon; up to 0.015 hydrogen; incidental impurities; and titanium.

[0091] Clause 27. The titanium alloy article of clause 20 or claim 21, wherein the second titanium alloy is an alpha-beta titanium alloy comprising, in weight percentages: 5.5 to 6.5 aluminum; 3.5 to 4.5 vanadium; 0 to 0.25 iron; up to 0.13 oxygen; up to 0.03 nitrogen; up to 0.08 carbon; up to 0.0125 hydrogen; incidental impurities; and titanium.

[0092] Clause 28. A method for manufacturing the titanium article of any preceding clause, the method comprising: disposing the first layer on the second layer so that at least a portion of the first layer contacts the second layer to thereby form an assembly; and metallurgically bonding the first layer to the second layer to thereby form a metallurgically bonded part.

[0093] Clause 29. A method of manufacturing a titanium alloy article, comprising: disposing a first titanium alloy part on a second titanium alloy part so that at least a portion of the first titanium alloy part contacts the second titanium alloy part to thereby form an assembly; wherein the first titanium alloy part has a first hardness, the second titanium alloy part has a second hardness, and the first hardness is 10 HBWto 100 HBW greater than the second hardness; and metallurgically bonding the first titanium alloy part to the second titanium alloy part to thereby form a metallurgically bonded part.

[0094] Clause 30. The method of clause 29, wherein metallurgically bonding the first titanium alloy part to the second titanium alloy part comprises: securing the first titanium alloy part to the second titanium alloy part to form a secured assembly; and hot rolling the secured assembly to form a metallurgical bond between the first titanium alloy part and the second titanium alloy part.

[0095] Clause 31. The method of any of clauses 29-30, wherein securing the first titanium alloy part to the second titanium alloy part to form the secured assembly comprises weldingtogether the first titanium alloy part and the second titanium alloy part about a periphery of the assembly.

[0096] Clause 32. The method of any of clauses 29-31, wherein hot rolling the metallurgically secured assembly comprises reducing a thickness of the metallurgically secured assembly to a thickness suitable for an armor.

[0097] Various non-limiting embodiments are described and illustrated in this specification to provide an overall understanding of the disclosed inventions. It is understood that the various non-limiting embodiments described and illustrated in this specification are nonlimiting and non-exhaustive. Thus, the invention is not limited by the description of the various non-limiting and non-exhaustive embodiments disclosed in this specification.Rather, the invention sought to be patented is defined solely by the claims. The features and characteristics illustrated and / or described in connection with various non-limiting embodiments may be combined with the features and characteristics of other non-limiting embodiments. Such modifications and variations are intended to be included within the scope of this specification. As such, the claims may be amended or supplemented to recite any features or characteristics expressly or inherently described in, or otherwise expressly or inherently supported by, this specification. Further, applicant reserves the right to amend the claims to affirmatively disclaim features or characteristics that may be present in the prior art. The various non-limiting embodiments disclosed and described in this specification can comprise, consist of, or consist essentially of the features and characteristics as variously described herein.

[0098] In this specification, other than where otherwise indicated, all numerical parameters are to be understood as being prefaced and modified in all instances by the term "about", in which the numerical parameters possess the inherent variability characteristic of the underlying measurement techniques used to determine the numerical value of the parameter. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter described in the present description should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0099] Also, any numerical range recited in this specification is intended to include all subranges of the same numerical precision subsumed within the recited range. For example, a range of "1 to 10" is intended to include all sub-ranges between (and including) the recited minimum value of 1 and the recited maximum value of 10, that is, having a minimum value equal to or greater than 1 and a maximum value equal to or less than 10, such as, forexample, 2.4 to 7.6. Any maximum numerical limitation recited in this specification is intended to include all lower numerical limitations subsumed therein, and any minimum numerical limitation recited in this specification is intended to include all higher numerical limitations subsumed therein. Accordingly, Applicant reserves the right to amend this specification, including the claims, to expressly recite any sub-range subsumed within the ranges expressly recited herein. All such sub-ranges are intended to be inherently described in this specification such that amending to expressly recite any such sub-ranges would comply with the requirements of 35 U.S.C. §§ 112 and 132(a). Additionally, as used herein when referring to compositional elemental ranges, the term “up to” includes zero unless the particular element is an unavoidable impurity.

[0100] The grammatical articles "one", "a", "an", and "the", as used in this specification, are intended to include "at least one" or "one or more", unless otherwise indicated. Thus, the grammatical articles are used in this specification to refer to one or more than one ( / .e., to "at least one") of the grammatical objects of the article. By way of example only, "a component" means one or more components and, thus, possibly, more than one component is contemplated and may be employed or used in an implementation of the described embodiments. Further, the use of a singular noun includes the plural, and the use of a plural noun includes the singular, unless the context of the usage requires otherwise.

[0101] One skilled in the art will recognize that the herein described alloys and methods, and the discussion accompanying them, are used as examples for the sake of conceptual clarity and that various modifications are contemplated. Consequently, as used herein, the specific examples / embodiments set forth and the accompanying discussion are intended to be representative of their more general classes. In general, use of any specific exemplar is intended to be representative of its class and should not be taken as limiting. While the present disclosure provides descriptions of various specific embodiments for the purpose of illustrating various aspects of the present disclosure and / or its potential applications, it is understood that variations and modifications will occur to those skilled in the art.Accordingly, the invention or inventions described herein should be understood to be at least as broad as they are claimed and not as more narrowly defined by particular examples and illustrative embodiments provided herein.

Claims

CLAIMSWhat is claimed is:

1. A titanium alloy article comprising:a first layer comprising a first titanium alloy having a first hardness;a second layer comprising a second titanium alloy having a second hardness, wherein the first hardness is 10 HBW to 100 HBW greater than the second hardness; and a metallurgical bond between the first layer and the second layer.

2. A titanium alloy article comprising:a first layer comprising a first titanium alloy having a first hardness in a range of 300 HBW to 400 HBW;a second layer comprising a second titanium alloy having a second hardness in a range of 250 HBW to 370 HBW, wherein the second hardness is less than the first hardness; anda metallurgical bond between the first titanium alloy and the second titanium alloy.

3. A titanium alloy article, comprising:a first layer comprising a first titanium alloy;a second layer comprising a second titanium alloy ;anda metallurgical bond between the first titanium alloy and the second titanium alloy, wherein the titanium alloy article exhibits at least one of the following:an Emof at least 1.38 when tested with 0.50 caliber AP M2;an Emof at least 1.37 when tested with 20 mm fragment simulating projectile; and an Emat least 5% greater than an Emof a homogeneous monolayer of a titanium alloy as measured with at least two different ballistic projectiles.

4. The titanium alloy article of any of claims 1-3, wherein the first titanium alloy has an elongation in a range of 8% to 20%.

5. The titanium alloy article of any of claims 1-3, wherein the second titanium alloy has an elongation in a range of 10% to 20%.

6. The titanium alloy article of any of claims 1-3, wherein the first titanium alloy has an elongation in a range of 13% to 15% and the second titanium alloy has an elongation in a range of 14% to 16%.

7. The titanium alloy article of any of claims 1 and 3, wherein the first titanium alloy has a first hardness in a range of 300 HBW to 380 HBW.

8. The titanium alloy article of any of claims 1 and 3, wherein the second titanium alloy has a second hardness in a range of 280 HBW to 370 HBW.

9. The titanium alloy article of any of claims 1-3, wherein the titanium alloy article exhibits an Emof at least 1.38 when tested with 0.50 caliber AP M2.

10. The titanium alloy article of any of claims 1-3, wherein the titanium alloy article exhibits an Emof at least 1.37 when tested with 20 mm fragment simulating projectile.

11. The titanium alloy article of any of claims 1-3, wherein the first layer comprises a first thickness and the second layer comprises a second thickness, wherein a ratio of the first thickness to the second thickness is in a range of 25:75 to 75:25.

12. The titanium alloy article of any of claims 1-3, wherein the first titanium alloy has a longitudinal yield strength in a range of 135 ksi to 160 ksi.

13. The titanium alloy article of any of claims 1-3, wherein the second titanium alloy has a longitudinal yield strength in a range of 105 ksi to 140 ksi.

14. The titanium alloy article of any of claims 1-3, wherein the first titanium alloy has a longitudinal ultimate tensile strength in a range of 150 ksi to 175 ksi.

15. The titanium alloy article of any of claims 1-3, wherein the second titanium alloy has a longitudinal ultimate tensile strength in a range of 120 ksi to 160 ksi.

16. The titanium alloy article of any of claims 1-3, wherein the first titanium alloy is an alpha-beta titanium alloy comprising, in weight percentages:2.0 to 7.0 aluminum;at least 2.1 vanadium;a molybdenum equivalency in a range of 2.0 to 5.0;0.1 to 4.0 cobalt;up to 0.5 oxygen;up to 0.25 nitrogen;up to 0.3 carbon;incidental impurities; andtitanium.

17. The titanium alloy article of any of claims 1-3, wherein the second titanium alloy is an alpha-beta titanium alloy comprising, in weight percentages:2.0 to 7.0 aluminum;at least 2.1 vanadium;a molybdenum equivalency in a range of 2.0 to 5.0;0.1 to 4.0 cobalt;up to 0.5 oxygen;up to 0.25 nitrogen;up to 0.3 carbon;incidental impurities; and titanium.

18. The titanium alloy article of any of claims 1-3, wherein the second titanium alloy is an alpha-beta titanium alloy comprising, in weight percentages:3.5 to 4.5 aluminum;2.0 to 3.0 vanadium;1.2 to 1.8 iron;up to 0.3 oxygen;up to 0.03 nitrogen;up to 0.08 carbon;up to 0.015 hydrogen;incidental impurities; andtitanium.

19. The titanium alloy article of any of claims 1-3, wherein the titanium alloy article comprises an armor, a blast-protective hull, a blast-protective V-shaped hull, a blast-protective vehicle underbelly, a blast-protective enclosure, or a combination thereof.

20. A titanium alloy article comprising:a first layer comprising a first titanium alloy;a second layer comprising a second titanium alloy; anda metallurgical bond between the first layer and the second layer,wherein the first titanium alloy is an alpha-beta titanium alloy comprising, in weight percentages:2.0 to 7.0 aluminum;at least 2.1 vanadium;a molybdenum equivalency in a range of 2.0 to 5.0;0.1 to 4.0 cobalt;up to 0.5 oxygen;up to 0.25 nitrogen;up to 0.3 carbon;incidental impurities; andtitanium.

21. A titanium alloy article comprising:a first layer comprising a first titanium alloy;a second layer comprising a second titanium alloy; anda metallurgical bond between the first layer and the second layer,wherein the first titanium alloy is an alpha-beta titanium alloy comprising, in weight percentages:4.75 to 5.25 aluminum;2.25 to 2.75 vanadium;3.8 to 4.2 tin;0.8 to 1.2 cobalt;up to 0.25 oxygen;up to 0.25 nitrogen;up to 0.02 carbon;0.6 to 1 iron;incidental impurities; andtitanium.

22. The titanium alloy article of claim 20 or claim 21 , wherein the second titanium alloy is an alpha-beta titanium alloy comprising, in weight percentages:2.0 to 7.0 aluminum;at least 2.1 vanadium;a molybdenum equivalency in a range of 2.0 to 5.0;0.1 to 4.0 cobalt;up to 0.5 oxygen;up to 0.25 nitrogen;up to 0.3 carbon;incidental impurities; andtitanium.

23. The titanium alloy article of claim 20 or claim 21 , wherein the second titanium alloy is an alpha-beta titanium alloy comprising, in weight percentages:4.75 to 5.25 aluminum;2.25 to 2.75 vanadium;3.8 to 4.2 tin;0.8 to 1.2 cobalt;up to 0.25 oxygen;up to 0.25 nitrogen;up to 0.02 carbon;0.6 to 1 iron;incidental impurities; andtitanium.

24. The titanium alloy article of claim 20 or claim 21 , wherein the second titanium alloy is an alpha-beta titanium alloy comprising, in weight percentages:3.6 to 4.1 aluminum;2.25 to 2.75 vanadium;2.5 to 2.9 tin;1 to 1.4 cobalt;0.35 to 0.65 iron;up to 0.25 oxygen;up to 0.25 nitrogen;up to 0.02 carbon;up to 0.015 hydrogen;incidental impurities; andtitanium.

25. The titanium alloy article of claim 20 or claim 21 , wherein the second titanium alloy is an alpha-beta titanium alloy comprising, in weight percentages:3.5 to 4.5 aluminum;2.0 to 3.0 vanadium;1.2 to 1.8 iron;up to 0.3 oxygen;up to 0.05 nitrogen;up to 0.08 carbon;up to 0.015 hydrogen;incidental impurities; andtitanium.

26. The titanium alloy article of claim 20 or claim 21 , wherein the second titanium alloy is an alpha-beta titanium alloy comprising, in weight percentages:5.5 to 6.75 aluminum;3.5 to 4.5 vanadium;0 to 0.4 iron;up to 0.2 oxygen;up to 0.05 nitrogen;up to 0.08 carbon;up to 0.015 hydrogen;incidental impurities; andtitanium.

27. The titanium alloy article of claim 20 or claim 21 , wherein the second titanium alloy is an alpha-beta titanium alloy comprising, in weight percentages:5.5 to 6.5 aluminum;3.5 to 4.5 vanadium;0 to 0.25 iron;up to 0.13 oxygen;up to 0.03 nitrogen;up to 0.08 carbon;up to 0.0125 hydrogen;incidental impurities; andtitanium.

28. A method for manufacturing the titanium article of any preceding claim, the method comprising:disposing the first layer on the second layer so that at least a portion of the first layer contacts the second layer to thereby form an assembly; andmetallurgically bonding the first layer to the second layer to thereby form a metallurgically bonded part.

29. A method of manufacturing a titanium alloy article, comprising:disposing a first titanium alloy part on a second titanium alloy part so that at least a portion of the first titanium alloy part contacts the second titanium alloy part to thereby form an assembly;wherein the first titanium alloy part has a first hardness, the second titanium alloy part has a second hardness, and the first hardness is 10 HBWto 100 HBW greater than the second hardness; andmetallurgically bonding the first titanium alloy part to the second titanium alloy part to thereby form a metallurgically bonded part.

30. The method of claim 29, wherein metallurgically bonding the first titanium alloy part to the second titanium alloy part comprises:securing the first titanium alloy part to the second titanium alloy part to form a secured assembly;andhot rolling the secured assembly to form a metallurgical bond between the first titanium alloy part and the second titanium alloy part.

31. The method of claim 29, wherein securing the first titanium alloy part to the second titanium alloy part to form the secured assembly comprises welding together the first titanium alloy part and the second titanium alloy part about a periphery of the assembly.

32. The method of claim 29, wherein hot rolling the metallurgically secured assembly comprises reducing a thickness of the metallurgically secured assembly to a thickness suitable for an armor.

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