PRIORITY INFORMATION
FIELD
[0002] The present application generally relates to components formed of titanium alloys.
In particular, the components formed of titanium alloys disclosed herein are particularly
suitable for use in rotary machines, such as gas turbines.
BACKGROUND
[0003] At least some known rotary machines such as, but not limited to, steam turbine engines
and/or gas turbine engines, include various rotor assemblies, such as a fan assembly,
a compressor, and/or turbines that each includes a rotor assembly. At least some known
rotor assemblies include components such as, but not limited to, disks, shafts, spools,
bladed disks ("bladed disks"), seals, and/or bladed integrated rings ("blings") and
individual dovetail attached blades. Such components may be subjected to different
temperatures depending on an axial position within the gas turbine engine.
[0004] For example, during operation, at least some known gas turbine engines may be subjected
to an axial temperature gradient that extends along a central longitudinal axis of
the engine. Generally, gas turbine engine components are exposed to lower operating
temperatures towards a forward portion of the engine and higher operating temperatures
towards an aft portion of the engine. As such, known rotor assemblies and/or rotor
components are generally fabricated from materials capable of withstanding an expected
maximum temperature at its intended position within the engine.
[0005] To accommodate different temperatures, different engine components have been forged
with different alloys that have different material properties that enable the component
to withstand different expected maximum radial and/or axial temperatures. More specifically,
known rotary assemblies and/or rotary components are each generally forged from a
single alloy that is capable of withstanding the expected maximum temperature of the
entire rotary assembly and/or rotary component. For example, Ti-17 (Ti-5Al-4Mo-4Cr-2Sn-2Zr),
Ti-6246 (Ti-6Al-2Sn-4Zr-6Mo), and Ti-64 (Ti-6Al-4V) can be utilized for rotary components
within a gas turbine engine depending on the part's relative position within the engine.
[0006] Ti-64 is an alpha/beta processed titanium alloy that is highly manufacturable, has
relatively isotropic properties, has a relatively low density, is tolerant to foreign
object damage (FOD), is relatively easy to repair, and is relatively low cost. However,
Ti-64 has limited thick section strength and high-cycle fatigue (HCF) capability.
In contrast, Ti-17 and Ti-6246 are beta processed, are not as easily manufacturable,
have more anisotropic properties (especially ductility) as a result of beta processing,
have higher density, are not as tolerant to FOD, are not as easily repairable, and
have a higher cost. However, Ti-17 and Ti-6246 have good thick section strength, have
good HCF capability, and have a superior temperature capability than Ti-64.
[0007] As such, a need exists for a low-cost titanium alloy that has the good qualities
of Ti-64 (e.g., relatively isotropic properties, a relatively low density, is tolerant
to FOD, is repairable) with some of the benefits of Ti-17 and Ti-6246 (e.g., thick
section strength and HCF).
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] A full and enabling disclosure of the present disclosure, including the best mode
thereof, directed to one of ordinary skill in the art, is set forth in the specification,
which makes reference to the appended figures, in which:
FIG. 1 is a cross-sectional view of a gas turbine engine in accordance with an exemplary
aspect of the present disclosure;
FIG. 2 is an isometric view of a bladed disk, as an example of a turbine component
suitable for use in a gas turbine engine, such as shown in FIG. 1; and
FIG. 3 is a sectional view of two stages of a bladed disk showing an optional location
of a weld zone, such as in the bladed disk of FIG. 2.
DEFINITIONS
[0009] The word "exemplary" is used herein to mean "serving as an example, instance, or
illustration." Any implementation described herein as "exemplary" is not necessarily
to be construed as preferred or advantageous over other implementations. Additionally,
unless specifically identified otherwise, all embodiments described herein should
be considered exemplary.
[0010] The singular forms "a", "an", and "the" include plural references unless the context
clearly dictates otherwise.
[0011] The term "at least one of" in the context of, e.g., "at least one of A, B, and C"
refers to only A, only B, only C, or any combination of A, B, and C.
[0012] The phrases "X to Y", "from X to Y", and "between X and Y" each refers to a range
of values inclusive of the endpoints (i.e., refers to a range of values that includes
both X and Y). Here and throughout the specification and claims, range limitations
are combined and interchanged, such ranges are identified and include all the sub-ranges
contained therein unless context or language indicates otherwise. For example, all
ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently
combinable with each other.
[0013] As used herein, the term "substantially free" is understood to mean completely free
of said constituent, or inclusive of trace amounts of same. "Trace amounts" are those
quantitative levels of chemical constituent that are barely detectable and provide
no benefit to the functional or aesthetic properties of the subject composition. The
term "substantially free" also encompasses completely free.
[0014] The term "turbomachine" refers to a machine including one or more compressors, a
heat generating section (e.g., a combustion section), and one or more turbines that
together generate a torque output.
[0015] The term "gas turbine engine" refers to an engine having a turbomachine as all or
a portion of its power source. Example gas turbine engines include turbofan engines,
turboprop engines, turbojet engines, turboshaft engines, etc., as well as hybrid-electric
versions of one or more of these engines.
[0016] Chemical elements are discussed in the present disclosure using their common chemical
abbreviation, such as commonly found on a periodic table of elements. For example,
hydrogen is represented by its common chemical abbreviation H; helium is represented
by its common chemical abbreviation He; and so forth.
[0017] The term "yield strength" refers to the stress at which a material begins to exhibit
plastic deformation (permanent deformation) without any increase in load. It is the
point on the stress-strain curve where the material transitions from elastic deformation
(reversible) to plastic deformation (irreversible). 0.2% yield strength is the strength
measured at 0.2% plastic strain beyond yield strength. It is easier and more reproducible
to measure than the yield strength. 0.2% yield strength is an important parameter
in determining the structural integrity and stability of a material under load.
[0018] The term "ultimate tensile strength" ("UTS") is the maximum stress a material can
withstand before fracturing or breaking. It is the highest point on the stress-strain
curve and represents the material's maximum strength under tensile loading. Once the
UTS is reached, the material experiences necking (localized deformation) and ultimately
fails.
[0019] The term "plastic elongation" refers to a material's ability to plastically deform
under tensile stress without fracturing. It is an important mechanical property that
measures the extent to which a material can be permanently deformed without breaking.
Ductile materials can undergo large plastic deformation before failure, while brittle
materials tend to fracture without significant deformation. Plastic elongation is
typically measured as the percentage increase in length between two marks placed on
the gage length prior to the test and the final distance between the two marks after
the test is completed and the two fractured specimen halves are fit back together.
A higher plastic elongation indicates greater ductility, as it indicates that the
metal can deform significantly before fracturing. Conversely, a lower plastic elongation
suggests lower ductility, meaning the metal is more brittle and prone to fracture
without significant plastic deformation.
[0020] The "reduction in area" (also expressed as "%RA") refers to a measurement quantifying
the extent of deformation or plastic flow that occurs in a metal specimen during mechanical
testing. When a metal specimen is subjected to tensile forces, it undergoes plastic
deformation in the form of elongation and reduction in cross-sectional area. The reduction
in area is a measurement of the decrease in the cross-sectional area of the specimen
after it fractures or fails during the testing process. The reduction in area is typically
expressed as a percentage and is calculated using the following formula: Reduction
in Area = [(Original cross-sectional area - Final cross-sectional area) / Original
cross-sectional area] x 100. A higher reduction in area indicates greater ductility,
as it indicates that the metal can deform significantly before fracturing. Conversely,
a lower reduction in area suggests lower ductility, meaning the metal is more brittle
and prone to fracture without significant plastic deformation.
[0021] Values disclosed for 0.2% yield strength, the ultimate tensile strength, plastic
elongation, and the reduction in area are measured at room temperature (i.e., 20 °C
to 25 °C) according to ASTM E8/E8M, also known as the Standard Test Methods for Tension
Testing of Metallic Materials. ASTM E8/E8M is a widely used standard in the field
of materials testing, including for alloy characterization, that provides guidelines
for conducting tension tests to determine the mechanical properties of metallic materials.
In addition to ASTM E8/E8M, all the tensile tests were run at a controlled strain
rate of 0.005 in/in ± 0.002 in/in per minute. After the 0.2 percent yield point has
been reached and the load has stabilized, the crosshead speed was 0.05 ± 0.01 in/in
of the length of the reduced section of the specimen per minute. Plastic elongation
and %RA were measured using the "fit-back method" whereby fracture surfaces of the
failed specimens were fit back together to measure the length change and reduced cross
area needed to calculate these parameters. All tensile testing was performed on bars
with a gage diameter of at least 0.14" and a gage length of at least 0.75".
[0022] The "ballistic impact resistance" refers to a material's ability to resist the penetration
or deformation caused by projectiles or high-velocity impacts. It is particularly
important in applications where protection against bullets, shrapnel, or other projectiles
is required. Materials with high ballistic impact resistance are designed to absorb
and dissipate the energy of the impact, reducing the damage caused by the projectile.
The resistance to ballistic impact damage, or foreign object damage, was measured
using a compressed ballistic rig firing approximately 4.45 mm diameter ball bearing
Cr-steel alloy balls weighing 0.36g and having a hardness of 55 Rockwell C at speeds
ranging from approximately 182.9 meters per second to approximately 304.8 meters per
second into targets of the alloys under test, with the sample thickness of 0.762 mm.
The extent of damage was quantified by summing the total radial crack length for crack(s)
emanating from the impact site. For avoidance of doubt, only radial crack lengths
are summed, while any circumferential cracking associated with the impact site was
not considered.
[0023] The term "weight percent" (abbreviated herein as wt%) refers to the concentration
of the amount of a particular element in the titanium alloy. The weight percent represents
the proportion of the element's weight relative to the total weight of the titanium
alloy, expressed as a percentage. Weight percent is calculated by dividing the weight
of the element by the total weight of the titanium alloy and multiplying the result
by 100.
DETAILED DESCRIPTION
[0024] Reference will now be made in detail to present embodiments of the disclosure, one
or more examples of which are illustrated in the accompanying drawings. The detailed
description uses numerical and letter designations to refer to features in the drawings.
Like or similar designations in the drawings and description have been used to refer
to like or similar parts of the disclosure.
[0025] A turbine component is generally provided that is comprised of a titanium alloy that
has been modified from Ti-64 in order to preserve the desired properties of Ti-64
(e.g., relatively isotropic properties, a relatively low density, tolerance to FOD,
repairability, and low cost) while improving the thick section strength, HCF capability,
creep strength, and low deformation following FOD to approach those beneficial aspects
of Ti-17 and Ti-6246. The cost of the new modified Ti-64 alloy can be minimized by
designing the composition such that a high percentage of widely available Ti-64 recycled
materials can be used. Additionally, the billet and forge processing approach may
be kept as close to Ti-64 as possible in order to minimize cost, while allowing for
a large scale production of such turbine components from the titanium alloy.
[0026] As stated, a turbine component within a turbofan engine, such as shown in FIG. 1,
can be constructed from a titanium alloy. The titanium alloy includes 5.50 wt% to
6.90 wt% aluminum; 3.50 wt% to 4.50 wt% vanadium; 0.01 wt% to 0.03 wt% carbon; 0.20
wt% to 0.70 wt% iron; 1.00 wt% to 1.50 wt% molybdenum; 0.10 wt% to 0.30 wt% silicon;
up to 0.21 wt% oxygen; up to 0.016 wt% nitrogen (e.g., up to 0.015 wt% nitrogen);
and a balance of titanium. In particular embodiments, the titanium alloy has a 0.2%
yield strength of 1000 MPa or greater (e.g., 1000 MPa to 1380.0 MPa), an ultimate
tensile strength of 1060 MPa or greater (e.g., 1060 MPa to 1450 MPa), a plastic elongation
of 15.0% or greater (e.g., 15.0% to 30.0%), a ballistic impact resistance measured
by a crack length of 3.048 mm or less (e.g., 0 mm to 3.048 mm), a reduction in area
that is 45 %RA or greater (e.g., 45 %RA to 75 %RA), or any combination of these properties.
[0027] Silicon (Si) is included within the titanium alloy to increase strength. It has been
found that less than 0.10 wt% of Si does not impart sufficient strength to the titanium
alloy. Additionally, it was found that more than 0.30 wt% Si results in poorer ballistic
impact resistance, poorer plastic elongation, poorer reduction in area, or a combination
thereof. Additionally, it was found that increased levels of Si above 0.30 wt% may
result in Si segregation issues during large diameter ingot solidification that would
be necessary for large scale production and manufacturing processes.
[0028] Iron (Fe) is included within the titanium alloy to enhance high-temperature strength
and to increase the temperature width of the alpha + beta phase field, thereby increasing
the hot working processing flexibility. It has been found that at least 0.20 wt% of
Fe, in conjunction with 1.00 wt% to 1.50 wt% Mo, leads to a desired balance of strength
and plastic elongation. However, Fe segregates strongly during solidification of large
diameter ingots, and it was found that a maximum of 0.70 wt% of Fe avoids production
issues in large scale production and manufacturing processes.
[0029] Molybdenum (Mo) is included within the titanium alloy to enhance high-temperature
strength and creep resistance and to increase the temperature width of the alpha +
beta phase field, thereby increasing the hot working processing flexibility. It has
been found that at least 1.00 wt% Mo, in conjunction with 0.20 wt% to 0.70 wt% Fe,
leads to a desired balance of strength and plastic elongation. However, the presence
of too much Mo within the titanium alloy may degrade the plastic elongation, reduction
in area and/or ballistic impact resistance of the titanium alloy. Thus, it has been
found that more than 1.50 wt% degrades the plastic elongation, reduction in area and/or
ballistic impact resistance of the titanium alloy beyond what would be desirable.
Increased levels of Mo also lead to an increase in the titanium alloy density.
[0030] Nitrogen (N) is present in the titanium alloys due to inevitable pick-up during vacuum
melting step(s) in the production of the titanium alloy. N will increases the strength
and hardness of a titanium alloy. However, too much N present in the titanium alloy,
such as above 0.016 wt% nitrogen (e.g., above 0.015 wt% nitrogen), leads to lower
plastic elongation, lower reduction in area, and/or lower ballistic impact resistance.
[0031] Oxygen (O) is naturally present in titanium alloys due to titanium's high oxidation
rate and can be intentionally added to meet a desired chemistry. However, the amount
of O present is minimized in the titanium alloys presently disclosed, as it has been
found that more than 0.21 wt% O in the titanium alloy would lead to reduced plastic
elongation, reduction in area, and/or ballistic impact resistance.
[0032] Carbon (C) is naturally present in titanium alloys due to low levels in the input
materials used in formulation and can be intentionally added to meet a desired chemistry.
A certain amount of C above 0.01 wt% is beneficial to 0.2 % yield strength and ultimate
tensile strength without degrading plastic elongation, reduction in area and/or ballistic
impact resistance; however, above 0.03 wt% of carbon present in the alloy leads to
a reduction in plastic elongation, reduction in area and/or ballistic impact resistance.
[0033] In particular embodiments, other elements may be avoided from inclusion within the
titanium alloy so as to avoid undesired characteristics. For example, the inclusion
of certain elements may hinder large scale use, such as in a large scale manufacturing
production of such turbine components.
[0034] While copper (Cu) may provide increased strength to a titanium alloy, it has been
found that the presence of Cu results in severe segregation during large diameter
ingot solidification and may lead to production chemistry and microstructural control
issues at large-scale. Thus, the presence of Cu in the titanium alloy may form a non-homogeneous
titanium alloy material that would not be suitable for manufacturing of turbine components
with consistent composition within each component and across all the components. As
such, the titanium alloy is substantially free from Cu to avoid these issues that
would hinder use of the titanium alloy in large scale manufacturing settings.
[0035] While chromium (Cr) may provide increased strength to the titanium alloy, it has
been found that the presence of Cr results in segregation during solidification and
may lead to production chemistry and microstructural control issues at large-scale.
Thus, the presence of Cr in the titanium alloy may form a non-homogeneous titanium
alloy material that would not be suitable for manufacturing of turbine components
with consistent composition within each component and across all the components. As
such, the titanium alloy is substantially free from Cr (e.g., no more than any residual
amount of Cr present due to Cr presence in the Ti sponge, such as no more than 500
wppm, e.g., no more than 200 wppm), in certain embodiments, to avoid these issues
that would hinder use of the titanium alloy in large scale manufacturing settings.
[0036] While tin (Sn) may provide increased strength to the alloy, particularly at elevated
temperatures, it was found that the presence of Sn results in decrease plastic elongation,
a decrease in reduction in area, and a decrease in ballistic impact resistance. Thus,
the titanium alloy is substantially free from Sn, in certain embodiments, to avoid
these issues.
[0037] While nickel (Ni) may provide increased strength to the alloy, it was found that
the presence of Ni results in segregation during solidification and may lead to production
chemistry and microstructural control issues at large-scale. Thus, the presence of
Ni in the titanium alloy may form a non-homogeneous titanium alloy material that would
not be suitable for manufacturing of turbine components with consistent composition
within each component and across all the components. As such, the titanium alloy is
substantially free from Ni (e.g., no more than any residual amount of Ni present due
to Ni presence in the Ti sponge, such as no more than 500 wppm, e.g., no more than
200 wppm), in certain embodiments, to avoid these issues that would hinder use of
the titanium alloy in large scale manufacturing settings.
[0038] While zirconium (Zr) may provide increased strength to the titanium alloy, particularly
at elevated temperatures, it has been found that the presence of Zr and Si in the
titanium alloy forms a mixed (TiZr)
6Si
3 silicide particle that will rapidly degrade plastic elongation, decrease the reduction
in area, and decrease the ballistic impact resistance. Thus, the titanium alloy is
substantially free from Zr, in certain embodiments, to avoid these issues.
[0039] While tungsten (W) may provide increased strength and creep strength to the titanium
alloy, the inclusion of W may lead to a non-homogeneous alloy material because of
W's relatively high density compared to Ti. Thus, the titanium alloy is substantially
free from W, in certain embodiments, to avoid this issue.
[0040] In particular embodiments, the titanium alloy described herein may be forged from
a section of cylindrical billet to a shape closer to the finished turbine component
in one or more steps below the beta transus, which is the temperature on heating at
which all the low temperature alpha, close-packed hexagonal phase disappears and the
high temperature beta, body-centered cubic phase is present. The forging temperature
may be below the beta transus temperature of the titanium alloy, and may be varied
from 14 °C to 83 °C below the beta transus temperature.
[0041] The forged shape may be solution heat treated at a temperature closer to the beta
transus than the forging temperature to control the volume fractions of primary alpha
phase and the beta phase. For example, the solution temperature may be varied typically
from 17 °C to 69 °C below the beta transus temperature and the solution time should
be for at least 1 hour.
[0042] It is well known that increasing the cooling rate following solution heat treatment
may result in an increase in 0.2% yield strength and ultimate tensile strength. For
the purposes of this application, all alloys were solution heat treated and cooled
at a rate of approximately 208 °C/min corresponding to about 80 mm section size in
a component that is water quenched from solution heat treatment. Accordingly, all
the tensile properties measured and reported here correspond to those tensile properties
expected in large section size components, on the order of 101.6 mm, that would be
liquid quenched (e.g. water, oil, polymer, etc.) or gas cooled (e.g. air, helium,
etc.) following solution heat treatment. It is well known that higher strengths may
be achieved via increasing cooling rate following solution heat treatment. The post-solution
cooling rate at any location in a heat treated component may be directly measured
using embedded thermocouples, or estimated using a finite element model, or some combination
of both. The post-solution cooling rate may be measured and/or calculated between
a temperature of approximately 28 °C below the solution temperature to 83 °C below
the solution temperature.
[0043] Following solution heat treatment and cooling, the component may be overaged at 537.8
°C to 760 °C for at least 1.5 hours (e.g., 2 hours) in order to minimize remaining
residual stresses from the solution heat treatment and cooling while retaining the
balance of 0.2% yield strength, ultimate tensile strength, plastic elongation, reduction
in area and ballistic impact resistance. Through these processing methods, the desired
characteristics of the titanium alloy may be achieved, such as a 0.2% yield strength
of 1000 MPa or greater (e.g., 1000 MPa to 1380 MPa), an ultimate tensile strength
of 1060 MPa or greater (e.g., 1060 MPa to 1450 MPa), a plastic elongation of 15.0%
or greater (e.g., 15.0% to 30.0%), a ballistic impact resistance measured by a crack
length of 3.048 mm or less (e.g., 0 mm to 3.048 mm), a reduction in area that is 45
%RA or greater (e.g., 45 %RA to 75 %RA), or any combination of these properties discussed
above.
[0044] As stated, the titanium alloy described herein may be utilized for forming a turbine
component, such as for use in an exemplary turbofan engine. FIG. 1 is a schematic
illustration of an exemplary turbofan engine 10 having a central rotational axis 12.
In the exemplary embodiment, turbofan engine 10 includes an air intake side 14 and
an exhaust side 16. Turbofan engine 10 also includes a core gas turbine engine 18
that includes a high-pressure compressor 20, a combustor 22, and a high-pressure turbine
24. Moreover, turbofan engine 10 includes a low-pressure turbine 26 that is disposed
axially downstream from core gas turbine engine 18, and a fan assembly 28 that is
disposed axially upstream from core gas turbine engine 22. Fan assembly 28 includes
an array of fan blades 30 extending radially outward from a rotor hub 32. Furthermore,
turbofan engine 10 includes a first rotor shaft 34 disposed between fan assembly 28
and the low-pressure turbine 26, and a second rotor shaft 36 disposed between high-pressure
compressor 20 and high-pressure turbine 24 such that fan assembly 28, high-pressure
compressor 20, high-pressure turbine 24, and low-pressure turbine 26 are in serial
flow communication and co-axially aligned with respect to central rotational axis
12 of turbofan engine 10.
[0045] During operation, air enters through intake side 14 and flows through fan assembly
28 to high-pressure compressor 20. Compressed air is delivered to combustor 22. Airflow
from combustor 22 drives high-pressure turbine 24 and low-pressure turbine 26 prior
to exiting turbofan engine 10 through exhaust side 16.
[0046] High-pressure compressor 20, combustor 22, high-pressure turbine 24, and low-pressure
turbine 26 each include at least one rotor assembly. Rotary or rotor assemblies are
generally subjected to different temperatures depending on their relative axial position
within turbofan engine 10. For example, in the exemplary embodiment, turbofan engine
10 has generally cooler operating temperatures towards forward fan assembly 28 and
hotter operating temperatures towards aft high-pressure compressor 20. As such, rotor
components within high-pressure compressor 20 are generally fabricated from materials
that are capable of withstanding higher temperatures as compared to fabrication materials
for rotor components of fan assembly 28.
[0047] While turbofan engine 10, represents one member of the class of rotary machines,
other members include land-based gas turbines, turbojets, turboshaft engines, unducted
engines, unducted fans, fixed-wing and propeller rotors, and the like, as well as
distributed propulsors such as distributed fans or pods, and the like. The turbine
component formed of the titanium alloy described herein may be in form of a rotary
machine part(s) useful in operating such rotary machines. Exemplary rotary machine
parts include, for example, a disk, bladed disk, airfoil, blade, vane, integral bladed
rotor, frame, fairing, seal, gearbox, case, mount, shaft, and the like.
[0048] FIG. 2 shows an example of a turbine component that may be constructed from a titanium
alloy, depicting an isometric view of a single stage bladed disk 50, alternatively
known as an integrally bladed rotor. The bladed disk 50 has a hub 52 that circumscribes
the central rotational axis 12, reference also the axis 12 of turbofan engine 10 of
FIG. 1. Extending substantially radially from hub 52 are airfoils 60. In the high-pressure
compressor 20 of FIG. 1, to optimize the bladed disk for performance parameters such
as, for example, fatigue life, FOD tolerance, and creep strength, a bi-metallic bladed
disk, where the hub 52 and airfoils 60 are different alloys, may be preferred. The
airfoil 60 may be solid state welded to the hub 52 utilizing processes such as translation
friction welding or linear friction welding. Therefore, it may be desirable to select
a material that provides excellent thick section properties for the hub 52, and excellent
fatigue properties in relatively small section sizes and FOD properties for the airfoil
60.
[0049] In the exemplary embodiment shown in FIG. 2, hub 52 is made from a titanium alloy
as described herein, with the airfoil 60 being made from a commercially available,
or conventional, materials with desirable fatigue life performance, such as, for example
Ti-64. After welding, the interface between hub 52 and airfoil 60 can be referred
to as the weld or heat affected zone 70. In this zone 70, a mix of hub and airfoil
alloys are present, along with a wide range of microstructures. This mix of alloys
and range of microstructures may compromise the thick section fatigue, FOD, etc. of
the portion of the bladed disk 50.
[0050] In another exemplary embodiment, hub 52 and airfoil 60 are both made from the same
titanium alloy of the present disclosure, or made from separate example titanium alloys
of the present disclosure. In the case of the hub 52 and airfoil 60 being the same
titanium alloy, in zone 70, no mix of hub and airfoil alloys are present, but a wide
range of microstructures exists. This range of microstructures may again compromise
the thick section fatigue, FOD, etc. of the portion of the bladed disk 50.
[0051] To optimize the mass of rotating components (via eliminating bolted joints), and
to take advantage of higher temperature materials, in a high pressure compressor 20,
shown in FIG. 1, adjacent stages of bladed disks may be inertia welded. Similar to
the bi-metallic hub/airfoil, it may be desirable to have a front bladed disk stage
made from a first material and an aft stage bladed disk made from a second material.
As shown in FIG. 3, the front bladed disk stage 80 may be made from an example titanium
alloy of the present disclosure and the aft bladed disk stage 90 may be made from
conventional material, such as, for example Ti-17. Again the weld zone or heat affected
zone 70 is present and a mix of front bladed disk and aft bladed disk alloys are present,
along with a wide range of microstructures in zone 70, representing an area of reduced
material properties.
[0052] In other exemplary embodiments, adjacent front bladed disk stage 80 and aft bladed
disk stage 90 are both made from the same titanium alloy of the present disclosure,
or may be made from separate example titanium alloy of the present disclosure.
[0053] Furthermore, for the embodiments described by FIG. 2 and FIG. 3, any example titanium
alloy of the present disclosure may be used alone or in combination with commercially
available alloys for one or more of the airfoil 60, hub 52, bladed disk 50, front
stage bladed disk 80 or back stage bladed disk 90. Although FIG. 3 describes two stages,
more than two stages of bladed disks may be contemplated.
[0054] While materials may be selected for these properties alone, consideration should
be made for recovering material property loss due to the weld-induced thermal environment
seen in a translation friction welding or linear friction welding via post treatment,
such as, for example, furnace heat treatment. As will be discussed below, the titanium
alloy of the present disclosure pairs well with commercially available titanium alloys,
allowing manufacturers to take full advantage of this bi-metallic material property
benefit by, for example, better matching heat treatment temperatures and processing
between the hub 52 material and airfoil 60 material and between the materials of adjacent
bladed disk stages 80 and 90. These benefits can also be realized when the titanium
alloy of the present disclosure is welded with itself, not only with commercially
available titanium alloys. In the case of a translation friction welded bi-metallic
bladed disk, use of the titanium alloy of the present disclosure as the hub in place
of beta processed Ti-17 or beta processed Ti-6246, and Ti-64 as the airfoil will result
in a better matching of flow stresses and microstructures between the titanium alloy
of the hub and the Ti-64 alloy airfoil. This may result in a solid state weld having
a lower tendency to form defects during or following the welding process.
[0055] Example components may have a thick section, be cast and wrought, or be a structural
aerospace casting, or the like.
EXAMPLES
[0056] Exemplary alloys (E-1 to E-20) were created according to the chemistries shown in
Table 1. These Exemplary Alloys were formed via an open die forgeprocess designed
to re-create a typical production billet conversion process; first hot working the
as-cast ingot above the beta transus, followed by sub-transus hot working that resulted
in beta recrystallization as the material was subsequently re-heated above the beta
transus and further hot worked, followed by water quenching. Finally, the material
was re-heated to below the beta transus and hot worked to final diameter. All hot
working was accomplished using open die forging, like that used in large-scale production
ingot to billet processing, with the intent that the microstructure and texture of
the sub-scale materials was representative of larger, production-scale material.
[0057] Comparative alloys are discussed below and shown in Tables 2, 3A, and 3B. The alloys
of Table 1, Table 2, Table 3A, and Table 3B were cooled from alpha + beta solution
heat treatment at 208 °C/minute. These alloys were measured to determine the 0.2%YS,
the UTS, the % plastic elongation, and the % reduction in area, according to ASTM
E8/E8M at 23 °C.
[0058] The 23°C 0.2% YS data from the alloys shown in Table 1 were input into a multiple
linear regression statistical model using commercially available statistical analysis
package (MiniTab V. 20.2). The following elements were determined to be statistically
significant using a p-test with a >95% confidence level for each element's statistical
significance: Al, O, Fe, Si, Mo. The model for yield strength prediction is shown
in Equation 1:
0.2% YS (MPa) = 469.3 + 48.8*Al (wt%) + 748*O (wt%) + 96.1*Fe (wt%) + 188*Si (wt%)
+ 57.7*Mo (wt%)
[0059] For high strength Ti alloy applications, it is desirable for a candidate alloy to
have 0.2% YS ≥ 1000 MPa at 23°C.
[0060] The 23°C UTS data from the alloys shown in Table 1 were input into a multiple linear
regression statistical model using commercially available statistical analysis package
(MiniTab V. 20.2). The following elements were determined to be statistically significant
using a p-test with a >95% confidence level for each element's statistical significance:
Al, O, Fe, Si, Mo. The model for Ultimate tensile strength prediction is shown in
Equation 2:
UTS (Mpa) = 612.1 + 39.2*Al (wt%) + 666*O (wt%) + 74.6*Fe (wt%) + 202*Si (wt%) + 41.6Mo
(wt%)
[0061] For high strength Ti alloy applications, it is desirable for a candidate alloy to
have UTS ≥ 1060 MPa at 23°C.
[0062] The 23°C %Plastic Elongation (%EL) from the alloys shown in Table 1 were input into
a multiple linear regression statistical model using commercially available statistical
analysis package (MiniTab V20.2). Note, the statistical analysis was performed using
Log(10) transformation of the % plastic elongation values, as is standard practice
for lognormally distributed data (
J Chen, Z Wang et al., Int. J. Plast. 152 (2022) 103260). The following elements were determined to be statistically significant using a
p-test with a >95% confidence level for each element's statistical significance: Fe,
Si, Mo. The model for yield strength prediction is shown in Equation 3:

[0063] For high strength Ti alloy applications, it is desirable for a candidate alloy to
have % plastic elongation ≥ 15.0% at 23°C.
[0064] The 23°C % Reduction in Area (%RA) from the alloys shown in Table 1 were input into
a multiple linear regression statistical model using commercially available statistical
analysis package (MiniTab V20.2). Note, the statistical analysis was performed using
Log(10) transformation of the % reduction in area values, as is standard practice
for lognormally distributed data (J Chen, Z Wang et al., Int. J. Plast. 152 (2022)
103260). The following elements were determined to be statistically significant using
a p-test with a >95% confidence level for each element's statistical significance:
Fe, Si, Mo. The model for yield strength prediction is shown in Equation 4:

[0065] For high strength Ti alloy applications, it is desirable for a candidate alloy to
have % reduction in area ≥ 45.0% at 23°C.
[0066] In certain embodiments, it is desirable for high strength Ti alloys to have both
high strength (≥ 1000 MPa 0.2% YS, according to Equation 1) as well as high % plastic
elongation (≥ 15.0%, according to Equation 3).
[0067] Comparative alloys (C-1 to C-20) were also created according to the chemistries shown
in Table 2. These Comparative Alloys were open die forged as with the exemplary alloys
of Table 1. The alloys of Table 2 were measured for their respective properties according
to ASTM E8/E8M at 23 °C. As shown in the results of Table 2, these comparative alloys
did not meet the specifications of the desired titanium alloy.
[0068] Comparative alloys (C-21 to C-50) were also created according to the chemistries
shown in Table 3A, and comparative alloys (C-51 to C-66) were also created according
to the chemistries shown in Table 3B. As shown in the results of Tables 3A and 3B,
these comparative alloys did not meet the specifications of the desired titanium alloy.
[0069] The alloy data from
U.S. Patent Publication Number 2017/0268091 is shown recreated in Table 4, as comparative alloys (Comp-A to Comp-M). The alloys
of Table 4 were cast as ingots and then extruded down to final size in the alpha/beta
phase field, not following a typical open-die forge billet process. It is likely that
this extrusion process resulted in a different combination of 0.2% yield strength,
ultimate tensile strength, % plastic elongation and % reduction in area due to differences
in texture induced by the extrusion process. This process is completely different
than what could be used in large scale manufacturing production. Thus, while alloy
Comp-G meets some of the targeted alloy characteristics, the predicted elongation
is low for an alloy that would be processed according to an open die forge process,
as utilized with the Exemplary Alloys of Table 1. Thus, it is believed that the alloy
Comp-G would lead to an alloy with reduced elongation than shown in Table 4 during
large-scale processes. While alloy Comp-J meets some of the targeted alloy characteristics,
the presence of copper is problematic for the alloy Comp -J's use in a large scale
manner. That is, the presence of copper would result in severe segregation during
large diameter ingot solidification and would lead to production chemistry and microstructural
control issues at large-scale.
Table 3A: Comparative Alloys (tested at 23 °C)
Alloy Ref. |
Al (wt%) |
V (wt%) |
C (wt%) |
O (wt%) |
Fe (wt%) |
Si (wt%) |
Cu (wt%) |
Mo (wt%) |
Sn (wt%) |
N (wt%) |
.2% YS (MPa) |
UTS (MPa) |
El (%) |
RA (%) |
Log (EL) |
Log (RA) |
C-21 |
6.36 |
4.14 |
0.03 |
0.19 |
0.20 |
|
0.22 |
|
|
0.002 |
959 |
1020 |
12.0 |
31.5 |
1.08 |
1.50 |
C-22 |
6.36 |
4.14 |
0.03 |
0.19 |
0.20 |
|
0.22 |
|
|
0.002 |
967 |
1028 |
14.5 |
40.6 |
1.16 |
1.61 |
C-23 |
6.25 |
3.92 |
0.02 |
0.18 |
0.21 |
0.67 |
0.20 |
|
|
0.002 |
1078 |
1145 |
8.1 |
15.1 |
0.91 |
1.18 |
C-24 |
6.25 |
3.92 |
0.02 |
0.18 |
0.21 |
0.67 |
0.20 |
|
|
0.002 |
1085 |
1156 |
8.3 |
15.3 |
0.92 |
1.18 |
C-25 |
6.22 |
3.85 |
0.03 |
0.17 |
0.22 |
|
1.38 |
|
|
0.002 |
1027 |
1089 |
8.5 |
15.6 |
0.93 |
1.19 |
C-26 |
6.22 |
3.85 |
0.03 |
0.17 |
0.22 |
|
1.38 |
|
|
0.002 |
1031 |
1096 |
8.2 |
15.9 |
0.91 |
1.20 |
C-27 |
6.21 |
4.10 |
0.03 |
0.19 |
0.22 |
0.30 |
1.48 |
|
|
0.002 |
1 075 |
1135 |
7.4 |
17.0 |
0.87 |
1.23 |
C-28 |
6.21 |
4.10 |
0.03 |
0.19 |
0.22 |
0.30 |
1.48 |
|
|
0.002 |
1078 |
1144 |
9.1 |
19.0 |
0.96 |
1.28 |
C-29 |
6.10 |
3.96 |
0.03 |
0.19 |
0.21 |
|
0.78 |
|
|
0.009 |
984 |
1036 |
10.3 |
21.1 |
1.01 |
1.32 |
C-30 |
6.10 |
3.96 |
0.03 |
0.19 |
0.21 |
|
0.78 |
|
|
0.009 |
985 |
1036 |
11.7 |
24.0 |
1.07 |
1.38 |
C-31 |
6.08 |
4.10 |
0.03 |
0.20 |
0.22 |
0.50 |
0.85 |
|
|
0.008 |
1091 |
1142 |
3.8 |
0.0 |
0.58 |
n/a |
C-32 |
6.08 |
4.10 |
0.03 |
0.20 |
0.22 |
0.5 |
0.85 |
|
|
0.008 |
1096 |
1153 |
4.2 |
6.2 |
0.62 |
0.79 |
C-33 |
6.34 |
4.08 |
0.09 |
0.19 |
0.51 |
0.49 |
|
0.51 |
|
0.010 |
1101 |
1165 |
7.6 |
9.2 |
0.88 |
0.96 |
C-34 |
6.34 |
4.08 |
0.09 |
0.19 |
0.51 |
0.49 |
|
0.51 |
|
0.010 |
1102 |
1164 |
8.4 |
12.1 |
0.92 |
1.08 |
C-35 |
6.32 |
4.15 |
0.10 |
0.18 |
0.22 |
|
0.87 |
|
|
0.007 |
1032 |
1089 |
7.3 |
12.5 |
0.86 |
1.10 |
C-36 |
6.32 |
4.15 |
0.10 |
0.18 |
0.22 |
|
0.87 |
|
|
0.007 |
1040 |
1094 |
9.4 |
18.1 |
0.97 |
1.26 |
C-31 |
6.24 |
4.15 |
0.09 |
0.18 |
0.22 |
0.52 |
0.86 |
|
|
0.006 |
113.5 |
1194 |
3.9 |
6.2 |
0.59 |
0.19 |
C-38 |
6.24 |
4.15 |
0.09 |
0.18 |
0.22 |
0.52 |
0.86 |
|
|
0.006 |
1126 |
1182 |
3.8 |
6.2 |
0.58 |
0.79 |
C-39 |
6.23 |
4.08 |
0.12 |
0.17 |
0.52 |
|
0.85 |
0.50 |
|
0.006 |
1064 |
1118 |
9.5 |
23.0 |
0.98 |
1.36 |
C-40 |
6.23 |
4.08 |
0.12 |
0.17 |
0.52 |
|
0.85 |
0.5 |
|
0.006 |
1069 |
1120 |
13.8 |
27.2 |
1.14 |
1.43 |
C-41 |
6.21 |
4.12 |
0.09 |
0.15 |
0.52 |
0.56 |
0.88 |
0.51 |
|
0.007 |
1179 |
1233 |
3.0 |
5.8 |
0.48 |
0.76 |
C-42 |
6.21 |
4.12 |
0.09 |
0.15 |
0.52 |
0.56 |
0.88 |
0.51 |
|
0.007 |
1175 |
1230 |
4.2 |
5 |
0.62 |
0.70 |
C-43 |
6.23 |
4.03 |
0.09 |
0.21 |
0.21 |
0.50 |
|
|
|
0.007 |
1051 |
1122 |
10.1 |
20.2 |
1.00 |
1.31 |
C-44 |
6.23 |
4.03 |
0.09 |
0.21 |
0.21 |
0.5 |
|
|
|
0.007 |
1051 |
1117 |
10.2 |
23.8 |
1.01 |
1.38 |
C-45 |
6.24 |
4.18 |
0.04 |
0.23 |
0.52 |
|
0.87 |
0.54 |
|
0.011 |
1027 |
1080 |
10.7 |
22.3 |
1.03 |
1.35 |
C-46 |
6.24 |
4.18 |
0.04 |
0.23 |
0.52 |
|
0.87 |
0.54 |
|
0.011 |
1048 |
1102 |
11.4 |
23.1 |
1.06 |
1.36 |
C-47 |
6.21 |
4.16 |
0.03 |
0.20 |
0.52 |
0.56 |
0.86 |
0.52 |
|
0.007 |
1215 |
1273 |
3.4 |
0.0 |
0.53 |
n/a |
C-48 |
6.21 |
4.16 |
0.03 |
0.20 |
0.52 |
0.56 |
0.86 |
0.52 |
|
0.007 |
1149 |
1202 |
7.2 |
10.9 |
0.86 |
1.04 |
C-49 |
6.32 |
4.21 |
0.03 |
0.18 |
0.52 |
0.57 |
0.86 |
0.52 |
1.91 |
0.006 |
1189 |
1252 |
3.6 |
4.4 |
0.56 |
0.64 |
C-50 |
6.32 |
4.21 |
0.03 |
0.18 |
0.52 |
0.57 |
0.86 |
0.52 |
1.91 |
0.006 |
1185 |
1245 |
4 |
10.5 |
0.60 |
1.02 |
Table 3B: Comparative Alloys (tested at 23 °C)
Alloy Ref. |
Al (wt%) |
V (wt%) |
C (wt%) |
O (wl%) |
Fe (wt%) |
Si (wt%) |
Cu (wt%) |
Mo (wt%) |
Sn (wt%) |
N (wt%) |
.2% YS (MPa) |
UTS (MPa) |
El (%) |
RA (%) |
Log (EL) |
Log (RA) |
C-51 |
6.37 |
4.01 |
0.03 |
0.18 |
0.22 |
0.02 |
0.86 |
|
|
0.003 |
1023, |
1068 |
14.8 |
40.7 |
1.17 |
1.61 |
C-52 |
6.37 |
4.01 |
0.03 |
0.18 |
0.22 |
0.02 |
0.86 |
|
|
0.003 |
1010 |
1058 |
15 |
39.6 |
1.18 |
1.60 |
C-53 |
6.31 |
3.90 |
0.03 |
0.20 |
0.19 |
0.44 |
0.80 |
|
|
0.003 |
1125 |
1177 |
11.1 |
26.5 |
1.05 |
1.42 |
G-54 |
6.31 |
3.90 |
0.03 |
0.20 |
0.19 |
0.44 |
0.80 |
|
|
0.003 |
1135 |
1189 |
9.4 |
28.0 |
0.97 |
1.45 |
C-55 |
6.44 |
3.89 |
0.03 |
0.19 |
0.99 |
0.02 |
0.8.2 |
|
|
0.006 |
1081 |
1128 |
13.9 |
42.3 |
1.14 |
1.63 |
C-56 |
6.44 |
3.89 |
0.03 |
0.19 |
0.99 |
0.02 |
0.8.2 |
|
|
0.006 |
1070 |
1122 |
13.5 |
37.8 |
1.13 |
1.58 |
C-57 |
6.34 |
3.86 |
0.03 |
0.19 |
0.20 |
0.02 |
0.83 |
0.97 |
|
0.003 |
1061 |
1104 |
15.1 |
42.7 |
1.18 |
1.63 |
C-58 |
6.34 |
3.86 |
0.03 |
0.19 |
0.20 |
0.02 |
0.83 |
0.97 |
|
0.003 |
1055 |
1100 |
12.9 |
42.6 |
1.11 |
1.63 |
C-59 |
6.14 |
3.74 |
0.03 |
0.18 |
0.45 |
0.45 |
0.75 |
0.46 |
|
0.001 |
1123 |
1175 |
12.1 |
31.5 |
1.08 |
1.50 |
C-60 |
6.14 |
3.74 |
0.03 |
0.18 |
0.45 |
0.45 |
0.75 |
0.46 |
|
0.001 |
1121 |
1172 |
12.8 |
31.5 |
1.11 |
1.50 |
C-61 |
6.02 |
3.57 |
0.05 |
0.18 |
0.44 |
0.44 |
0.75 |
0.44 |
1.82 |
0.007 |
1158 |
1212 |
12.5 |
29.7 |
1.10 |
1.47 |
C-62 |
6.02 |
3.57 |
0.05 |
0.18 |
0.44 |
0.44 |
0.75 |
0.44 |
1.82 |
0.007 |
1162 |
1215 |
12.6 |
28.6 |
1.10 |
1.46 |
C-63 |
6.22 |
3.66 |
0.11 |
0.18 |
0.48 |
0.44 |
0.75 |
0.46 |
|
0.005 |
1170 |
1173 |
1.4. |
2.7 |
0.15 |
0.43 |
C-64 |
6.22 |
3.66 |
0.11 |
0.18 |
0.48 |
0.44 |
0.75 |
0.46 |
|
0.005 |
1134 |
1178 |
6.0 |
13.2 |
0.78 |
1.12 |
C-65 |
6.53 |
4.09 |
0.05 |
0.22 |
0.54 |
0.37 |
0.27 |
0.51 |
|
0.007 |
1149 |
1189 |
13.1 |
31.3 |
1.12 |
1.50 |
C-66 |
6.53 |
4.09 |
0.05 |
0.22 |
0.54 |
0.37 |
0.27 |
0.51 |
|
0.007 |
1139 |
1180 |
13.8 |
36.9 |
1.14 |
1.57 |
Table 4: Comparative Examples
|
Measured 0.2% YS |
Measured UTS |
Measured %EI |
|
Al (wt%) |
V (wt%) |
C (wt%) |
O (wt%) |
Fe (wt%) |
Si (wt%) |
Mo (wt%) |
N (wt%) |
Cu (wt%) |
Pred 0.2% YS (Mpa) |
Pred EL (%) |
111C/ min |
333C/ min |
111C/ min |
333C/ min |
111C/ min |
333C/min |
Comp-A |
6.715 |
3.98 |
0.014 |
0.159 |
0.178 |
0.021 |
0.003 |
0.009 |
0.004 |
938 |
15.0 |
861 |
887 |
972 |
997 |
17.0 |
19.5 |
Comp-B |
6.943 |
4.15 |
0.026 |
0.206 |
0.21 |
0.02 |
0.002 |
0.008 |
0.002 |
987 |
15.2 |
900 |
958 |
1012 |
1057 |
17.0 |
17.0 |
Comp-C |
7.293 |
3.918 |
0.018 |
0.201 |
0.173 |
0.031 |
0.002 |
0.387 |
0.003 |
999 |
14.8 |
|
|
|
|
|
|
Comp-D |
7.573 |
3.993 |
0.019 |
0.227 |
0.195 |
0.019 |
0.002 |
0.415 |
0.003 |
1032 |
15.1 |
|
|
|
|
|
|
Comp-E |
6.638 |
4.028 |
0.044 |
0.159 |
0.18 |
0.019 |
0.002 |
0.008 |
0.003 |
934 |
15.0 |
|
|
|
|
|
|
Comp-F |
6.693 |
4.003 |
0.102 |
0.179 |
0.183 |
0.016 |
0.003 |
0.008 |
0.003 |
951 |
15.1 |
940 |
966 |
1074 |
1088 |
17.0 |
17.0 |
Comp-G |
6.693 |
3.91 |
0.039 |
0.18 |
0.36 |
0.508 |
0.358 |
0.009 |
0.004 |
1082 |
9.8 |
1042 |
1069 |
1131 |
1152 |
17.0 |
16.5 |
Comp-H |
6.423 |
3.765 |
0.082 |
0.184 |
0.443 |
0.673 |
0.465 |
0.019 |
0.758 |
1117 |
8.6 |
1202 |
1214 |
1282 |
1262 |
9.5 |
3.9 |
Comp-I |
6.603 |
3.913 |
0.025 |
0.157 |
0.52 |
0.028 |
0.56 |
0.009 |
0.005 |
997 |
19.3 |
|
947 |
|
1115 |
0.0 |
19.0 |
Comp-J |
6.61 |
3.85 |
0.074 |
0.173 |
0.455 |
0.022 |
0.495 |
0.01 |
0.77 |
999 |
18.6 |
1070 |
1101 |
1145 |
1176 |
17.0 |
11.7 |
Comp-K |
6.683 |
3.923 |
0.014 |
0.153 |
0.175 |
0.635 |
0.003 |
0.009 |
0.002 |
1047 |
7.3 |
1006 |
1048 |
1105 |
1145 |
17.0 |
15.0 |
Comp-L |
6.605 |
3.93 |
0.019 |
0.159 |
0.173 |
0.023 |
0.002 |
0.009 |
0.308 |
932 |
14.9 |
914 |
957 |
1005 |
1031 |
19.0 |
18.0 |
Comp-M |
6.708 |
3.89 |
0.019 |
0.143 |
0.188 |
0.02 |
0.003 |
0.009 |
0.004 |
926 |
15.1 |
885 |
989 |
1002 |
1027 |
19.0 |
17.0 |
[0070] Further aspects are provided by the subject matter of the following clauses:
[0071] A turbine component comprising a titanium alloy, wherein the titanium alloy comprises:
5.50 wt% to 6.90 wt% aluminum; 3.50 wt% to 4.50 wt% vanadium; 0.01 wt% to 0.03 wt%
carbon; 0.20 wt% to 0.70 wt% iron; 1.00 wt% to 1.50 wt% molybdenum; 0.10 wt% to 0.30
wt% silicon; up to 0.21 wt% oxygen; up to 0.016 wt% nitrogen (e.g., up to 0.015 wt%
nitrogen); and a balance of titanium, wherein the titanium alloy is substantially
free from copper.
[0072] A turbine component comprising a titanium alloy, wherein the titanium alloy comprises:
5.50 wt% to 6.90 wt% aluminum; 3.50 wt% to 4.50 wt% vanadium; 0.01 wt% to 0.03 wt%
carbon; 0.20 wt% to 0.70 wt% iron; 1.00 wt% to 1.50 wt% molybdenum; 0.10 wt% to 0.30
wt% silicon; up to 0.21 wt% oxygen; up to 0.016 wt% nitrogen (e.g., up to 0.015 wt%
nitrogen); and a balance of titanium, wherein the Al, O, Fe, Si, Mo are present in
amounts that result in a predicted 23 °C 0.2% yield strength ≥1000 MPa according to
the formula: 469.3 + 48.8*Al (wt%) + 748*O (wt%) + 96.1*Fe (wt%) + 188*Si (wt%) +
57.7*Mo (wt%), and/or wherein the Fe, Si, Mo are present in amounts that result in
a predicted 23 °C % plastic elongation ≥15.0% according to the formula: 10^(1.149
+ 0.211*Fe (wt%) - 0.514*Si (wt%) + 0.076*Mo (wt%)).
[0073] The turbine component as in any preceding clause, wherein the titanium alloy is substantially
free from copper.
[0074] The turbine component as in any preceding clause, wherein the titanium alloy has
a 0.2% yield strength of 1000 MPa or greater.
[0075] The turbine component as in any preceding clause, wherein the titanium alloy has
a 0.2% yield strength of 1000 MPa to 1380 MPa.
[0076] The turbine component as in any preceding clause, wherein the titanium alloy has
an ultimate tensile strength of 1060 MPa or greater.
[0077] The turbine component as in any preceding clause, wherein the titanium alloy has
an ultimate tensile strength of 1060 MPa to 1450 MPa.
[0078] The turbine component as in any preceding clause, wherein the titanium alloy has
a plastic elongation of 15.0% or greater.
[0079] The turbine component as in any preceding clause, wherein the titanium alloy has
a plastic elongation of 15.0% to 30.0%.
[0080] The turbine component as in any preceding clause, wherein the titanium alloy has
a ballistic impact resistance measured by a crack length of 3.048 mm or less.
[0081] The turbine component as in any preceding clause, wherein the titanium alloy has
a ballistic impact resistance measured by a crack length of 0 mm to 3.048 mm.
[0082] The turbine component as in any preceding clause, wherein the turbine component has
a reduction in area that is 45 %RA or greater.
[0083] The turbine component as in any preceding clause, wherein the turbine component has
a reduction in area that is 45 %RA to 75 %RA.
[0084] The turbine component as in any preceding clause, wherein the titanium alloy has
a 0.2% yield strength of 1000 MPa or greater, an ultimate tensile strength of 1060
MPa or greater, a plastic elongation of 15.0% or greater and a reduction in area that
is 45 %RA or greater.
[0085] The turbine component as in any preceding clause, wherein the titanium alloy has
a 0.2% yield strength of 1000 MPa to 1380 MPa, an ultimate tensile strength of 1060
MPa to 1450 MPa, a ductility of 15.0% to 30.0%, and a reduction in area that is 45
%RA to 75 %RA.
[0086] The turbine component as in any preceding clause, wherein the titanium alloy is substantially
free from chromium.
[0087] The turbine component as in any preceding clause, wherein the titanium alloy is substantially
free from tin.
[0088] The turbine component as in any preceding clause, wherein the titanium alloy is substantially
free from nickel.
[0089] The turbine component as in any preceding clause, wherein the titanium alloy is substantially
free from zirconium.
[0090] The turbine component as in any preceding clause, wherein the titanium alloy is substantially
free from tungsten.
[0091] The turbine component as in any preceding clause, wherein the titanium alloy is substantially
free from any other elements.
[0092] The turbine component as in any preceding clause, wherein the Al, O, Fe, Si, Mo are
present in amounts that result in a predicted 23 °C 0.2% yield strength ≥1000 MPa
according to the formula: 469.3 + 48.8*Al (wt%) + 748*O (wt%) + 96.1*Fe (wt%) + 188*Si
(wt%) + 57.7*Mo (wt%).
[0093] The turbine component as in any preceding clause, wherein the Fe, Si, Mo are present
in amounts that result in a predicted 23 °C % plastic elongation ≥ 15.0% according
to the formula: 10^(1.149 + 0.211*Fe (wt%) - 0.514*Si (wt%) + 0.076*Mo (wt%)).
[0094] The turbine component as in any preceding clause, wherein the Al, O, Fe, Si, Mo are
present in amounts that result in a predicted 23 °C 0.2% yield strength ≥1000 MPa
according to the formula: 469.3 + 48.8*Al (wt%) + 748*O (wt%) + 96.1*Fe (wt%) + 188*Si
(wt%) + 57.7*Mo (wt%), and wherein the Fe, Si, Mo are present in amounts that result
in a predicted 23 °C % plastic elongation ≥ 15.0% according to the formula: 10^(1.149
+ 0.211*Fe (wt%) - 0.514*Si (wt%) + 0.076*Mo (wt%)).
[0095] The turbine component as in any preceding clause, wherein the titanium alloy comprises
3.80 wt% to 4.43 wt% vanadium.
[0096] The turbine component as in any preceding clause, wherein the titanium alloy comprises
0.45 wt% to 0.57 wt% iron.
[0097] The turbine component as in any preceding clause, wherein the titanium alloy comprises
0.14 wt% to 0.28 wt% silicon.
[0098] The turbine component as in any preceding clause, wherein the titanium alloy consists
essentially of: 5.50 wt% to 6.90 wt% aluminum; 3.50 wt% to 4.50 wt% vanadium; 0.01
wt% to 0.03 wt% carbon; 0.20 wt% to 0.70 wt% iron; 1.00 wt% to 1.50 wt% molybdenum;
0.10 wt% to 0.30 wt% silicon; up to 0.21 wt% oxygen; up to 0.016 wt% nitrogen (e.g.,
up to 0.015 wt% nitrogen); and a balance of titanium.
[0099] The turbine component as in any preceding clause, wherein the titanium alloy consists
of: 5.50 wt% to 6.90 wt% aluminum; 3.50 wt% to 4.50 wt% vanadium; 0.01 wt% to 0.03
wt% carbon; 0.20 wt% to 0.70 wt% iron; 1.00 wt% to 1.50 wt% molybdenum; 0.10 wt% to
0.30 wt% silicon; up to 0.21 wt% oxygen; up to 0.016 wt% nitrogen (e.g., up to 0.015
wt% nitrogen); and a balance of titanium.
[0100] A turbine component comprising a titanium alloy, wherein the titanium alloy consists
essentially of: 5.50 wt% to 6.90 wt% aluminum; 3.50 wt% to 4.50 wt% vanadium; 0.01
wt% to 0.03 wt% carbon; 0.20 wt% to 0.70 wt% iron; 1.00 wt% to 1.50 wt% molybdenum;
0.10 wt% to 0.30 wt% silicon; up to 0.21 wt% oxygen; up to 0.016 wt% nitrogen (e.g.,
up to 0.015 wt% nitrogen); and a balance of titanium.
[0101] A turbine component comprising a titanium alloy, wherein the titanium alloy consists
of: 5.50 wt% to 6.90 wt% aluminum; 3.50 wt% to 4.50 wt% vanadium; 0.01 wt% to 0.03
wt% carbon; 0.20 wt% to 0.70 wt% iron; 1.00 wt% to 1.50 wt% molybdenum; 0.10 wt% to
0.30 wt% silicon; up to 0.21 wt% oxygen; up to 0.016 wt% nitrogen (e.g., up to 0.015
wt% nitrogen); and a balance of titanium.
[0102] The turbine component as in any preceding clause, wherein the titanium alloy has
a 0.2% yield strength of 1000 MPa or greater.
[0103] The turbine component as in any preceding clause, wherein the titanium alloy has
a 0.2% yield strength of 1000 MPa to 1380 MPa.
[0104] The turbine component as in any preceding clause, wherein the titanium alloy has
an ultimate tensile strength of 1060 MPa or greater.
[0105] The turbine component as in any preceding clause, wherein the titanium alloy has
an ultimate tensile strength of 1060 MPa to 1450 MPa.
[0106] The turbine component as in any preceding clause, wherein the titanium alloy has
a plastic elongation of 15.0% or greater.
[0107] The turbine component as in any preceding clause, wherein the titanium alloy has
a plastic elongation of 15.0% to 30.0%.
[0108] The turbine component as in any preceding clause, wherein the titanium alloy has
a ballistic impact resistance measured by a crack length of 3.048 mm or less.
[0109] The turbine component as in any preceding clause, wherein the titanium alloy has
a ballistic impact resistance measured by a crack length of 0 mm to 3.048 mm.
[0110] The turbine component as in any preceding clause, wherein the turbine component has
a reduction in area that is 45 %RA or greater.
[0111] The turbine component as in any preceding clause, wherein the turbine component has
a reduction in area that is 45 %RA to 75 %RA.
[0112] The turbine component as in any preceding clause, wherein the titanium alloy has
a 0.2% yield strength of 1000 MPa or greater, an ultimate tensile strength of 1060
MPa or greater, a plastic elongation of 15.0% or greater, a crack length of 3.048
mm or less, and a reduction in area that is 45 %RA or greater.
[0113] The turbine component as in any preceding clause, wherein the titanium alloy has
a 0.2% yield strength of 1000 MPa to 1380 MPa, an ultimate tensile strength of 1060
MPa to 1450 MPa, a ductility of 15.0% to 30.0%, a ballistic impact resistance measured
by a crack length of 0 to 3.048 mm, and a reduction in area that is 45 %RA to 75 %RA.
[0114] A method of forming the turbine component of any preceding clause.
[0115] A method of forming a turbine component, the method comprising: forging a titanium
alloy into the turbine component, wherein the titanium alloy comprises: 5.50 wt% to
6.90 wt% aluminum; 3.50 wt% to 4.50 wt% vanadium; 0.01 wt% to 0.03 wt% carbon; 0.20
wt% to 0.70 wt% iron; 1.00 wt% to 1.50 wt% molybdenum; 0.10 wt% to 0.30 wt% silicon;
up to 0.21 wt% oxygen; up to 0.016 wt% nitrogen (e.g., up to 0.015 wt% nitrogen);
and a balance of titanium, wherein the titanium alloy is substantially free from copper.
[0116] A method of forming a turbine component, the method comprising: forging a titanium
alloy into the turbine component, wherein the titanium alloy comprises: 5.50 wt% to
6.90 wt% aluminum; 3.50 wt% to 4.50 wt% vanadium; 0.01 wt% to 0.03 wt% carbon; 0.20
wt% to 0.70 wt% iron; 1.00 wt% to 1.50 wt% molybdenum; 0.10 wt% to 0.30 wt% silicon;
up to 0.21 wt% oxygen; up to 0.016 wt% nitrogen (e.g., up to 0.015 wt% nitrogen);
and a balance of titanium, wherein the Al, O, Fe, Si, Mo are present in amounts that
result in a predicted 23 °C 0.2% yield strength ≥1000 MPa according to the formula:
469.3 + 48.8*Al (wt%) + 748*O (wt%) + 96.1*Fe (wt%) + 188*Si (wt%) + 57.7*Mo (wt%),
and/or wherein the Fe, Si, Mo are present in amounts that result in a predicted 23
°C % plastic elongation ≥15.0% according to the formula: 10^(1.149 + 0.211*Fe (wt%)
- 0.514*Si (wt%) + 0.076*Mo (wt%))
[0117] The method of any preceding clause, wherein forging the titanium alloy into the turbine
component comprises: forging the titanium alloy at a forging temperature that is below
a beta transus temperature of the titanium alloy.
[0118] The method of any preceding clause, wherein the method comprises: heat treating the
titanium alloy.
[0119] The method of any preceding clause, wherein the method comprises: solution heat treating
the titanium alloy at a heat treatment temperature that is below a beta transus temperature
of the titanium alloy.
[0120] The method of any preceding clause, wherein the heat treatment temperature is above
a forging temperature, wherein the titanium alloy is held at the heat treatment temperature
for at least 1 hour.
[0121] The method of any preceding clause, wherein the method comprises: after heat treating
the titanium alloy, cooling the titanium alloy to form the turbine component.
[0122] The method of any preceding clause, wherein cooling the titanium alloy is performed
with at cooling rate from the heat treatment temperature of 208 °C/min.
[0123] The method of any preceding clause, further comprising: following solution heat treatment
and cooling, heating the titanium alloy to an overage heat treatment temperature of
538 °C to 760 °C for at least 1.5 hours.
[0124] The method of any preceding clause, wherein the titanium alloy has a 0.2% yield strength
of 1000 MPa or greater.
[0125] The method of any preceding clause, wherein the titanium alloy has an ultimate tensile
strength of 1060 MPa or greater.
[0126] The method of any preceding clause, wherein the titanium alloy has a plastic elongation
of 15.0% or greater.
[0127] The method of any preceding clause, wherein the titanium alloy has a ballistic impact
resistance measured by a crack length of 3.048 mm or less.
[0128] The method of any preceding clause, wherein the titanium alloy has a reduction in
area that is 45 %RA or greater.
[0129] A titanium alloy formed according to the method of any preceding clause.
[0130] This written description uses examples to disclose the present disclosure, including
the best mode, and also to enable any person skilled in the art to practice the disclosure,
including making and using any devices or systems and performing any incorporated
methods. The patentable scope of the disclosure is defined by the claims, and may
include other examples that occur to those skilled in the art. Such other examples
are intended to be within the scope of the claims if they include structural elements
that do not differ from the literal language of the claims, or if they include equivalent
structural elements with insubstantial differences from the literal languages of the
claims.