heat treatments and applications of titanium alloys · 2020. 12. 10. · vacuum heat treatments,...
TRANSCRIPT
Heat Treatments and Applications of Titanium Alloys
Ing. Andrea Trombetta
Titanium Alloys Specialist at TAG srl (www.tag.it)
e-mail:[email protected]
Applied Metallurgy: academic year 2020/2021
TAG
December 2020
TAG HEAT TREATMENTS
TAG is a company specialized in the heat treatments and special processes for the aeronautical, energy and automotive markets.
The activities include: vacuum heat treatments, brazing, precipitation, ageing,
solubilisation, aluminizing, plasma nitriding, cryogenic treatment and other special processes.
Many different types of material can be treated such as, for example: tool steels, stainless steels, superalloys, titanium and light alloys.
PROCESS LISTHEAT TREATMENT
VACUUM BRAZING
PLASMA NITRIDING
COATING (Aluminizing and Chromizing)
STRIPPING
HFIC (Hydrogen Fluoride Ion Cleaning)
HIP (Hot Isostatic Pressing)
NDT (Non-Destructive Test)
LABORATORY
HEAT TREATMENT TYPESolution Treating Aging HT Hardening HT Tempering HT
ATMOSPHEREVacuum
(Low – High) Partial Pressure (Ar) Protective Atmosphere (Ar – N2) Air
COOLING
Vacuum Gas (Ar – N2) Protective Atmosphere (Ar – N2) Water (from 15 °C to 80 °C)
MATERIALNickel and Cobalt base Superalloys Steels Light Alloy (Aluminum and Titanium)
REFERENCE NORMSInternational Std. Customer Std.
REFERENCE APPROVALS & CUSTOMERSNADCAP CUSTOMERSAC 7102 GE AVIO GE AVIATION ROLLS ROYCE SAFRAN
AC 7102/S LIEBHERR AEROSPACE LEONARDO ELICOPTERS LEONARDO AIRCRAFT LEONARDO AEROSTRUCTURES
AC 7102/5 PARKER AEROSPACE MECAER AMERICA UTAS AEROSPACE SECONDO MONAAC 7102/8 AEREA UMBRA GROUP
HEAT TREATMENT
FURNACE BRAZING ATMOSPHERE
Vacuum (Low – High)
MATERIALSuperalloys Steels
REFERENCE NORMSInternational Std. Customer Std.
NADCAP AC 7102/1 GE AVIO 7120FAWS C3.6
BHGE ITN 07770.21AWS B2.2Spot Welding for Metallic Honeycomb Application & Small Thickness Sheet
VACUUM BRAZING
VACUUM BRAZING
ATMOSPHEREN2 - H2 N2 - H2 - CH4
MATERIALSteels and Titanium Alloys
REFERENCE NORMSInternational Std. Customer Std.
NADCAP AC 7102/4 UTC AEROSPACE SYSTEM U.T.175
GOODRICH ACTUATION SYSTEMS Ltd915-010-004
AMS 2759/8
PLASMA NITRIDING
PLASMA NITRIDING
COATING THERMO-CHEMICAL DIFFUSION PROCESSPack & Vapour Phase Processes
Ar – H2
MATERIALSuperalloys Steels
REFERENCE NORMSInternational Std. Customer Std.NADCAP AC 7109 CPM-SU-5012
NADCAP AC 7109/7 RPS 692
- ALUMINIZING - CHROMIZING
ALUMINIZING / CHROMIZING
PROCESSChemical StrippingREFERENCE NORMS
Several BHGE Oil&Gas SpecificationInternal Specification
Electrochemical Stripping(Development in Progress)
STRIPPING
STRIPPING
PROCESSVapor phase hydrogen fluoride ion cleaning (HFIC) is a super
cleaning.This is a process step in preparation for the repair of cracks and other damage found in field-run high-temperature gas
turbine and aero engine components.
Internal TAG cycles and specifications are applied to the repair of turbomachinery blades and vanes.
Development of repair programs EJ200 & CF6-80 are in progress
HFIC
HFIC: Hydrogen Fluoride Ion Cleaning
PROCESS
Hot isostatic pressing (HIP) is a process using high pressure and temperature over a set time to improve material properties.
Precisely computer controlled to specific parameters yield the desired improved properties. The heating chamber is placed inside a pressure vessel pressurized with argon. The uniform
pressure and elevated temperature allows for densification and elimination of any product defects while at the same time
improving the mechanical properties.As support to HIP activity a pilot installation is available for test and
qualification.
HIP: Hot Isostatic Pressing
HIP
NDT: Non Destructive TestingFluorescent Penetrant Inspection
Type I [Fluorescent] - Method A [water washable]Level 3- Form a/d [dry powder/solvent suspension]
Class 2 [Non halogenated solvents]
Type I - Method D - Level 3Form a/d [dry powder/solvent suspension]
Class 2 [Non halogenated solvents]
MATERIALSteels Superalloys Light Alloys
REFERENCE NORMSInternational Std. Customer Std.NADCAP AC 7114 GE Avio 9300F
NADCAP AC 7114/S BHGE ITN07042
NADCAP AC 7114/1 Cobham Mission Systems DS18.52
NADCAP AC 7114/1SASTM E-1417
LABORATORY
- OPTICAL MICROSCOPY - IMPACT TEST UP TO 450 J
- HARDNESS AND MICROHARDNESS - ROOM TEMPERATURE TENSILE TEST UP TO 100 kN
- SEM ANALISYS WITH EDSREFERENCE NORMS
International Std.NADCAP AC 7101/4NADCAP AC 7102/5
ASTM E384 - ASTM E10 - ASTM E110 - ASTM E18 - ASTM E92 –ASTM E8 – ASTM E23 – ASTM A370
bcc β
Hcp α
Temperature
β transus882°C
α stabilizers
β stabilizers
Neutralelements
Substitutional (Al)Interstitial (O, N, C)
(Sn, Zr)
β-isomorphous (V, Mo, Nb, Ta, Re)β-eutectoid (Fe, Mn, Cr, Si, Co, Ni, Cu, H)
TITANIUM ALLOYS (1)
TITANIUM ALLOYS (2)
With exclusively αstabilizers and neutral elements
≤ 2 wt.% β stabilizers≤ 10 vol.% β stabilizers
10-15 wt.% β stabilizers2-6 wt.% β stabilizers5-40 vol.% β stabilizers
About 30 wt.% β stabilizers
α' (exagonal) or α'' (orthorombic) martensite
Retained (or metastable) beta (βr)
Ms
β field
α+β fieldα field
882°C
Tem
pera
ture
Concentration of β stabilizers (Moeq)
High strength
Heavy stabilized
α alloys Near α alloys α+β alloys Metastable β
alloysStable β
alloys
Mf
α alloys Near α alloys α+β alloys Metastable β
alloysStable β
alloysDensity
Corrosion / Oxidation resistanceFormability
Weldability
+
+
+
+
Alloying
determines
Chemical / Physical propertiesBasis to increase strength
Strength
Solid solution strengthningPrecipitation hardening
+Transformation hardening
Work hardeningGrain boundary strenthening
+
Creep resistanceDuctility
Toughness
Processing
determines
Microstructure control
Balcance of mechanical propertiesf (microstructure)
TITANIUM ALLOYS (3)
Common name Composition (wt_%) β-transus (°C)
α alloys and commercially pure (CP) titaniumGrade 1 CP-Ti (0,2 Fe - 0,18 O) 890
Grade 2 CP-Ti (0,3 Fe - 0,25 O) 915
Grade 3 CP-Ti (0,3 Fe - 0,35 O) 920
Grade 4 CP-Ti (0,5 Fe - 0,40 O) 950
Grade 7 Ti-0,2Pd 915
Ti-5-2,5 / Grade 6 Ti-5Al-2,5Sn 1040
Near α alloys
Grade 12 Ti-0,3Mo-0,76Ni 880
Ti-8-1-1 Ti-8Al-1V-1Mo 1040
IMI 685 Ti-6Al-5Zr-0,5Mo-0,25Si 1020
Ti-6-2-4-2 Ti-6Al-2Sn-4Zr-2Mo-0,1Si 995
IMI 834 Ti-5,8Al-4Sn-3,5Zr-0,5Mo-0,7Nb-0,35Si-0,06C 1045
TITANIUM ALLOYS (4)
Common name Composition (wt_%) β-transus (°C)
α + β alloys
Ti-6-4 Ti-6Al-4V (O max. 0.20) 995
Ti-6-4 ELI Ti-6Al-4V (O max. 0.13) 975
Ti-6-6-2 Ti-6Al-6V-2Sn 945
IMI 550 Ti-4Al-2Sn-4Mo-0,5Si 975
Ti-6-2-4-6 Ti-6Al-2Sn-4Zr-6Mo 935
Timetal 367 Ti-6Al-7Nb (Biomedical) 1015
Metastable β alloys (I)
B120 VCA Ti-13V-11Cr-3Al 650
Β-CEZ Ti-5Al-2Sn-2Cr-4Mo-4Zr-1Fe 890
Ti-10-2-3 Ti-10V-2Fe-3Al 800
Ti-5553 Ti-5Al-5Mo-5V-3Cr 860
TITANIUM ALLOYS (5)
Common name Composition (wt_%) β-transus (°C)
Metastable β alloys (II)Ti-17 Ti-5Al-2Sn-2Zr-4Cr-4Mo 890
Ti-15-3 Ti-15V-3Cr-3Al-3Sn 760
Beta 21S Ti-15Mo-3Al-3Nb-0,2Si 800
Beta C Ti-3Al-8V-6Cr-4Mo-4Zr 730
- Ti-13Nb-13Zr (Biomedical) 735
TMMA Ti-11,5Mo-6Zr-4,5Sn (Biomedical) 750
- Ti-35Nb-5Ta-7Zr (Biomedical) -
- Ti-29Nb-13Ta-4,6Zr (Biomedical) -
- Ti-11,5Mo-6Zr-4,5Sn (Biomedical) 744
- Ti-12Mo-6Zr-2Fe (Biomedical) -
Stable β alloys (II)
Alloy C Ti-35V-15Cr -
TITANIUM ALLOYS (6)
CP-Ti 26%
β Alloys 4%
Other α+β Alloys 14%
Ti-6Al-4V 56%
Approximate breakdown of the USA market by alloy type (1998)
TITANIUM ALLOYS (7)
HEAT TREATMENTS OF TITANIUM ALLOYS
α+β Solution Treating
β Processing
Through TransusProcessing
Beta Alloys
Heavily StabilizedAlloys
High StrengthAlloys
β Solution Treating
CP Titanium&
Alpha AlloysAnnealing β annealing
Near αAlloys
α+β annealing
Alpha + BetaAlloys
β Annealing
α + β Annealing
Solution Treatingand Aging (STA)M
illAn
neal
ing
HEAT TREATMENTS AND APPLICATIONS OF CP
TITANIUM AND ALPHA ALLOYS
HEAT TREATMENTS OF ALPHA ALLOYS (1)
β
α+β
IHomogenixation
Tem
pera
ture
Time
β-transus
IIDeformation
IIIAnnealing
Annealing
Microstructure of CT Titanium after annealing 1h at 600°C.
HEAT TREATMENTS OF ALPHA ALLOYS (2)Annealing
Effect of Fe content on the grain size of CP titanium: (a) 0,15%; (b) 0,03%.
Material
Annealing Temperature Soak Time
Commercially Pure Titanium 650 – 815 (1) 650 – 815 (2) 15 - 120 60 – 120
Ti-5Al-2,5Sn 705 – 845 (3) 705 – 845 (3) 10 - 120 60 - 240
Ti-5Al-2,5Sn ELI 700 – 900 (3) 700 – 900 (3) 10 - 120 60 - 240
(1) Air cool or slower(2) Air cool followed by 595°C for 8 hrs and air cool(3) Air cool
HEAT TREATMENTS OF ALPHA ALLOYS (3)Annealing
APPLICATIONS OF CP TITANIUM AND ALPHA ALLOYS(1)
Industry Equipment Environment
Power generation Condensers, Heat exchangers, flue gas scrubbers
Acqueous solutions of variouspurity , S02 containing gasesSea water
Water plantsPetrolchemical industry
Desalination heat exchangersHeat exchangers, well heads, pipeAnd down hole hardware
H2S containing brines
Pulp and paper Diffusion washers in bleachingsection of process Choides containing liquids
Chemical industryMetal production
Dimensionally stable electrodesCathodes for electrotwinning Cu, Au, and Zn
Cl2 and Cl2 compoundsVarious aggressive acqueoussolutions
Mineral dressing Pressure vessels at high T and P Various aggressive acqueoussolutions
Biomedical device Orthopedic implants, surgicalimplants, surgical implements
Human body and autoclave sterilizers
Spacecraft Cryogenic tanks N2O4, liquid O2, liquid H2
Industrial uses for CP titanium and alpha alloys because of good corrosion resistance
APPLICATIONS OF CP TITANIUM AND ALPHA ALLOYS(2)
Condenser with titanium CP2 tubes.
POWER GENERATION
APPLICATIONS OF CP TITANIUM AND ALPHA ALLOYS(3)PULP AND PAPER INDUSTRY
Example of a very large structure used in the bleaching section of the pulp and paper production, CP titanium.
APPLICATIONS OF CP TITANIUM AND ALPHA ALLOYS(4)
Liquid hydrogen tank made of Ti6Al-2,5Sn ELI(Extra Low Interstitial) alloy
AEROSPACE INDUSTRY
APPLICATIONS OF CP TITANIUM AND ALPHA ALLOYS(5)BIOMEDICAL INDUSTRY
Example of a bone plate implant, CP titanium grade 3.
Example of acetabular cup in a hip implant, CP titanium.
Guggenheim Museum in Bilbao (Spain): 30.000 CP titanium sheets with 0,3 mm thickness were used for the external
coating.
Fukuoka (Japan) Dome with retractible titanium roof.
APPLICATIONS OF CP TITANIUM AND ALPHA ALLOYS(6)ARCHITECTURE
HEAT TREATMENTS AND APPLICATIONS OF
ALPHA + BETA ALLOYS
HEAT TREATMENTS OF ALPHA+BETA ALLOYS (1)
β
α+β
IHomogenixation
Tem
pera
ture
Time
β-transus
IV Stabilization
IIDeformation
IIIBeta Annealing
Beta Annealing
Microstructure of Ti-6Al-4V after beta annealing from 1030°C .1 – Precipitation of Ti3Al in α phase
2 – Precipitation of α secondarylamellae (αs) in β phase
STABILIZATION
HEAT TREATMENTS OF ALPHA+BETA ALLOYS (2)Beta Annealing
αGB (Grain Boundaries)
α side plates (Widmanstatten)
α colonyA – SLOW/MODERATE COOLING RATES
HEAT TREATMENTS OF ALPHA+BETA ALLOYS (3)
α basketweave
Beta AnnealingA – SLOW/MODERATE COOLING RATES
Beta Annealing
HEAT TREATMENTS OF ALPHA+BETA ALLOYS (4)
Basketweave
Microstructure of alloy Ti-6Al-4V after beta annealing from 1020°C: (a) non-polarized light; (b) polarized light.
Colony Colony
Basketweave
β
α+β
IHomogenixation
Tem
pera
ture
Time
β-transus
IV Stabilization
IIDeformation
IIIAlpha + Beta
Annealing
Alpha + Beta Annealing (A)
Bimodal microstructure of Ti-6Al-4V after alpha+betaannealing: primary alpha grains in a matrix of lamellar α+β.
HEAT TREATMENTS OF ALPHA+BETA ALLOYS (4)
1 – Precipitation of Ti3Al in α phase
2 – Precipitation of α secondarylamellae (αs) in β phase
STABILIZATION
Alpha+Beta Annealing (B)
β
α+β
IHomogenixation
Tem
pera
ture
Time
β-transus
IV Stabilization
IIDeformation
IIIAlpha + Beta
Annealing
Microstructure of Ti-6Al-4V after alpha+beta annealingat 920°C with furnace cooling: coarse alpha grains with
beta phase locaed at triple junction points.
HEAT TREATMENTS OF ALPHA+BETA ALLOYS (5)
1 – Precipitation of Ti3Al in α phase
2 – Precipitation of α secondarylamellae (αs) in β phase
STABILIZATION
β
α+β
IHomogenixation
Tem
pera
ture
Time
β-transus
IV Stabilization
IIDeformation
IIIAlpha + Beta
Annealing
Alpha+Beta Annealing (C)
HEAT TREATMENTS OF ALPHA+BETA ALLOYS (6)
Microstructure of Ti-6Al-4V after alpha+beta annealingat 704°C: fine alpha grains with beta phase locaed at
triple junction points.1 – Precipitation of Ti3Al in α phase
2 – Precipitation of α secondarylamellae (αs) in β phase
STABILIZATION
Beta Annealing
Fully LamellarMicrostructure
High Temperature Range
Alpha + Beta Annealing
Low Temperature Range
BimodalMicrostructure
Fine EquiaxedGrains
Coarse EquiaxedGrains
HEAT TREATMENTS OF ALPHA+BETA ALLOYS (7)
σ0.2
εF
HCF
LCF
ΔKmicro
ΔKmacro
KIC
Creep
α + β alloys
Tensile
Fatigue
FractureCreep
Propertiesσ0.2 Yield stressεF Final strain → ductilityHCF High cycle fatigue strength → Resustance to fatigue crack nucleationLCF Low cycle fatigue strengthΔKmicro Resistance to fatigue micro-crack propagationΔKmacro Resistance to fatigue macro-crack propagationKIC Fracture toughness
Creep strength
EquiaxedLamellarBimodal
HEAT TREATMENTS OF ALPHA+BETA ALLOYS (8)
Solution Treating and Aging (STA)
β
α+β
IHomogenixation
Tem
pera
ture
Time
β-transus
IV Solution treating
IIDeformation
IIIAlpha + Beta
Annealing
Fine equiaxedα+β
V Aging
WATER QUENCHING
HEAT TREATMENTS OF ALPHA+BETA ALLOYS (9)
IV SOLUTION TREATING
α' compact hexagonalmartensite
in some alloys:α'' Orthorhombic (or
soft) martensite
V AGING
α' → α + βor
α'' → α + β
Ms
β → α'
βα
Tem
pera
ture
→
Vandium Content →Ti-6Al-4V
Mf
β-transus
T1 T > 995°C
Ms
β → αp + α'
βα
Tem
pera
ture
→
Vandium Content →
Ti-6Al-4V
Mf
β-transusT2
900°C < T < 970°C
Ms
β → α + βr
βα
Tem
pera
ture
→
Vandium Content →
Ti-6Al-4V
Mf
β-transus
T3
T < 900°C
- Low strength- Good ductility
α + βr
Solution Treating and Aging (STA)HEAT TREATMENTS OF ALPHA+BETA ALLOYS (10)
α'
- High strength- Low ductility
T = 1020°C
- Good strength- Good ductility
α' + αp
T = 960°C T = 850°C
Alloyβ - Transus
Temperature(°C)
Solution Heat TreatingTemperature
Times at Temperature or SoakingTimes
CoolingMethodSheet, Strip and
Plate (°C)
Bars, Forgingsand Castings
(°C)
Sheet, Strip and Plate (min)
Bars, Forgingsand Castings
(min)
Ti-6Al-4V 995 900 - 970 900 - 970 2 - 90 20 – 120 Water
Ti-6Al-2Sn-4Zr-6Mo 935 815 - 915 815 - 915 2 - 90 20 – 120 Water (*)
Ti-6Al-6V-2Sn 945 870 - 925 870 - 925 2 - 60 20 - 90 Water (*)
(*) Air cooling may be applied in relative thin sections.
Solution Treating and Aging (STA)HEAT TREATMENTS OF ALPHA+BETA ALLOYS (11)
Nominal Thickness (mm) Maximum Quencing Delay Time (s) 1 , 2
Up to 6.4 6
6.5 to 25.3 8
25.4 and over 10
Notes1 Quenching delay time begins when the furnace door starts to open, and ends when the last corner of the load is immersed in the quenchant.2 Times shown aplies to Ti-6Al-4V and Ti-6Al-4V ELI. Alloys more beta stabilized are more tolerant of quenching dealy.
Solution Treating and Aging (STA)HEAT TREATMENTS OF ALPHA+BETA ALLOYS (12)
Solution Treating and Aging (STA)HEAT TREATMENTS OF ALPHA+BETA ALLOYS (13)
Solution Treating and Aging (STA)HEAT TREATMENTS OF ALPHA+BETA ALLOYS (14)
As quenched microstructures
Agin
g te
mpe
ratu
re (°
C)
Aged fine α + β
α'
β
β + α
α' + αp
β + α
αp and Aged fine α + β
α + βr
α and Aged fine α + β
β transus
1200
1000
800
600
400
200
Solution Treating and Aging (STA)
Fine α + β
Primary α
Microstructure of Ti-6Al-4V solution treating (910°C) and aging (540°C 6h).
HEAT TREATMENTS OF ALPHA+BETA ALLOYS (15)
α' → α + β (or βr → α + β)
T1
T2
T3T1 > T2 > T3
Aging time
Stre
ngth
T1
T2T3
T1 > T2 > T3
Aging time
Elon
gatio
n
Solution Treating and Aging (STA)Material Aging Temperature (°C) Soaking Time (hours)
Ti-6Al-4V 480 - 690 2 – 8
Ti-6Al-2Sn-4Zr-6Mo 480 - 675 4 - 8
Ti-6Al-6V-2Sn 470 - 620 2 - 10
HEAT TREATMENTS OF ALPHA+BETA ALLOYS (16)
In titanium alloys we have to take into account the strong affinity with oxygen which at elevatedtemperatures may lead to the formation of a brittle surface layer, known as the ,״alpha-case״ that is analpha phase enriched in oxygen that is extremely dangerous since it drastically reduces the fatigue life ofthe final component.
0-z x0
DISTACE FROM OXIDE/METAL INTERFACE
C0
Cs
Czo
Cz1
% O
XYG
EN
x0zTi
O2
Alph
a ca
se
Met
al
Max 14,3 wt_%
14,3 %
HEAT TREATMENTS OF ALPHA+BETA ALLOYS (17)Oxygen contamination
Alpha case layer in a Ti-6Al-4V component extruded in the beta field.
Alpha case layer in a Ti-6Al-4V component after solution treating ad aging.
Alpha case layer in a Ti-6Al-2Sn-4Zr-2Mo-0,08Si (near α alloy) exhaust
valve. In order to reduce the formation of alpha-case: Perform heat treatments in high vacuum furnaces or in argon atmosphere; Take into account a final grinding process after heat treatments; Take into account an acid pickling process (HF and HNO3) after heat
treatments.
HEAT TREATMENTS OF ALPHA+BETA ALLOYS (17)Oxygen contamination
APPLICATIONS OF ALPHA+BETA ALLOYS (1)AEROSPACE INDUSTRY
1 – AIRCRAFT STRUCTURAL PARTS
707727
737747
747SP
767
757
777
0%
2%
4%
6%
8%
10%
12%
1955 1960 1965 1970 1975 1980 1985 1990 1995 2000
AIRF
RAM
E %
TIT
ANIU
M
YEAR OF INTRODUCTION
2 – AERO ENGINES2.1 ROTATING PARTS (up to 300°C)(Blades, disks, …) 2.2 NON ROTATING PARTS(Casings, ducts, frames, stators, manifolds, …)
GE-90 aero-engine
APPLICATIONS OF ALPHA+BETA ALLOYS (2)AEROSPACE INDUSTRY
AIRCRAFT STRUCTURAL PARTS: FORGINGS
Titanium bulked after hot forging and machinig
Titanium structural component in a landig gear
Requirements: Resistance to fatigue
propagation of macrocracks Good fracture toughness (KIC)
Beta Annealing is sometimes performed
APPLICATIONS OF ALPHA+BETA ALLOYS (3)AEROSPACE INDUSTRY
AIRCRAFT STRUCTURAL PARTS: CASTINGS
Characteristics: Titanium castings exhibits a fully
lamella microstructure suitable for most applications.
Sometimes HIP (Hot Isostatic Pressing) may be introduced to reduce internal defects.
APPLICATIONS OF ALPHA+BETA ALLOYS (4)AEROSPACE INDUSTRYAERO ENGINES: ROTATING PARTS
Schematic view of Rolls Royce Trent 800 engine with detail of turbofanfan where 26 Ti-6Al-4V blades with
bimodal microstructure were used.
APPLICATIONS OF ALPHA+BETA ALLOYS (5)AEROSPACE INDUSTRYAERO ENGINES: ROTATING PARTS
Ti-6Al-4V blisks (baldes on disk) used in the front stages of LP compressor of aero engine EJ200 installed on the Eurofighter.
The blades are joined to disks by means of linear friction welding.
APPLICATIONS OF ALPHA+BETA ALLOYS (6)AEROSPACE INDUSTRYAERO ENGINES: ROTATING PARTS
1
2
3 4
1 – Fan with Ti-6Al-4V blades2 – Ti-6Al-4V blisks
3 – Ti-6Al-4V spool (front stages)4 – Ti-6Al-2Sn-4Zr-2Mo (rear stages)
Compressor spool for GE CF6 class engine usinginertia welding to connect the individual stages;
front stages: Ti-6Al-4V; rear stages: Ti-6242).
APPLICATIONS OF ALPHA+BETA ALLOYS (7)AEROSPACE INDUSTRY
AERO ENGINES: NON ROTATING PARTS
Superlastically formed and diffusion bonded (SPF/DB) titanium manifold.
Intermediate compressor casing of aero-engine TRENT XWB (Airbus A350XWB).
APPLICATIONS OF ALPHA+BETA ALLOYS (8)POWER GENERATION
STEAM TURBINE BLADES
Ti-6Al-4V laste stage blades of a large steam turbine rotor.
Parameter 50 inch 60 inch
Rotational speed 3600 rpm 3000 rpm
Blade length 1250 mm 1500 mm
Anulus area 11,5 m2 16,5 m2
Boss ratio (blade inner diameter/blade outer diameter) 0,40
Blade tip speed 786 m/s
Blade material Ti-6Al-4V alloy
APPLICATIONS OF ALPHA+BETA ALLOYS (8)OIL AND GAS INDUSTRY
Section of a drilling riser made from Ti-6Al-4V ELI.
Standard α+β annealing
Standard α+β annealing
Standard β annealing
Standard β annealing
ELI α+β annealing
ELI α+β annealing
ELI β annealing
ELI β annealing
0 50 100 150
KIC
KISCCKISCC
KIC
MPa(m)0,5
Honda RC30, produced between 1988 and 1992, was the only motorcycle to adopt titanium connecting rods produced with a technology specifically
developed by the Japanese manufacturer for mass production.
APPLICATIONS OF ALPHA+BETA ALLOYS (9)AUTOMOTIVE INDUSTRY
2018 Spa Francorchamps Grand Prix: incident between Fernando Alonso'sMclaren Honda and Charles Leclerc's Sauber Alfa Romeo. The latter has
been saved by halo, which contains an inner titanium alloy bar.
Titanium alloy halo
APPLICATIONS OF ALPHA+BETA ALLOYS (10)AUTOMOTIVE INDUSTRY
Titanium is one of the most commonly used material in biomedical industry, where it plays afundamental role thanks to its biocompatibility and non-toxic properties.In the specific case of endoprostheses, the porous oxide film that covers the surface of the metal(TiO2) constitutes a base and a substrate for the regrowth of bone tissues, giving rise to aphenomenon called osseointegration of the implant.
Ti-6Al-4V
APPLICATIONS OF ALPHA+BETA ALLOYS (11)BIOMEDICAL INDUSTRY
Investment cast Ti-6Al-4V golf club heads
Ti-6Al-4V watch
Ti-6Al-4V racketTi-3Al-2,5V (Grade 9 or «half-five»)bicycle frame
SPORT AND ENTERTAINMENTAPPLICATIONS OF ALPHA+BETA ALLOYS (12)
HEAT TREATMENTS AND APPLICATIONS OF NEAR ALPHA ALLOYS
HEAT TREATMENTS OF NEAR ALPHA ALLOYS (1)Beta Annealing
β
α+β
IHomogenixation
Tem
pera
ture
Time
β-transus
IV Stabilization
IIDeformation
IIIBeta Annealing
Ti3Al solvus
(Ti, Zr)5Si3 solvus
1 – Precipitation of Ti3Al in α phase
2 – Precipitation of α secondarylamellae (αs) in β phase
3 – Precititation of (Ti,Zr)5Si3compounds to enahance creep
resistance
STABILIZATION
Fully lamellar microstructure of near-α alloy IMI 834 after beta annealing.
HEAT TREATMENTS OF NEAR ALPHA ALLOYS (2)Alpha + Beta Annealing
β
α+β
IHomogenixation
Tem
pera
ture
Time
β-transus
IV Stabilization
IIDeformation
IIIAlpha + Beta
Annealing
Ti3Al solvus
(Ti, Zr)5Si3 solvus
Bimodal microstructure of Ti-6Al-2Sn-4Zr-2Mo-0,08Si after alpha + beta annealing.
1 – Precipitation of Ti3Al in α phase
2 – Precipitation of α secondarylamellae (αs) in β phase
3 – Precititation of (Ti,Zr)5Si3compounds to enahance creep
resistance
STABILIZATION
APPLICATIONS OF NEAR ALPHA ALLOYS (1)AEROSPACE INDUSTRY
REQUIREMENTS:1 – CREEP RESISTANCE2 – FATIGUE RESISTANCE3 – OXIDATION RESISTANCE
IMI 834IMI 685
Ti 6-2-4-2
Ti-6Al-4VCP Ti
400 500 600550450100
200
300
400
500
Temperature (°C)
Stress (MPa) for 0,2% creep strain 100 h
APPLICATIONS OF NEAR ALPHA ALLOYS (2)AEROSPACE INDUSTRY
Forged compressor disk or wheelmade form the near α alloy IMI 685.
Impeller used in a small engine for regional jets, Ti-6242, bimodal
microstructure.
High pressure compressor blisk used in EJ 200 aero-engine, IMI 834; bimodal
microstructure
APPLICATIONS OF NEAR ALPHA ALLOYS (3)AUTOMOTIVE INDUSTRY
INLET VALVES:Ti-6Al-4V Solution Treated and Aged
EXHAUST VALVES:Ti-6Al-2Sn-4Zr-2Mo-0,08Si with
fully lamellar microstructure
MV Agusta F4 RR
HEAT TREATMENTS AND APPLICATIONS OF
BETA ALLOYS
(a) (b)Effect of pre-aging (8h 500°C) on microstructureof heavy stabilized β alloy Beta 21S : (a) 16h at
690°C; (b) 8h at 500°C + 24 h at 725°C.
HEAT TREATMENTS OF BETA ALLOYS (1)A – HEAVILY STABILIZED BETA ALLOYS
(e.g. Beta 21S, Ti-15-3, Beta-C, …)
β
α+β
IHomogenixation
Tem
pera
ture
TimeVAging
β-transus
IV Pre-aging
IIDeformation
IIISolution Treating
Beta Solution Treating
IV PRE-AGING
βr → ωiso + β → ωiso + β → ωiso + α + βor
βr → β' + β → β' + β → β' + α + ββ
V AGING
ωiso + α + β → α + βor
β' + α + β → α + ββ
The typical problem arising after beta solutiontreating is the continuos network of alpha phase
(αGB) at beta grain bounderies.
αgb
HEAT TREATMENTS OF BETA ALLOYS (2)B – HIGH STRENGTH BETA ALLOYS
(e.g. Ti-17, β-CEZ, Ti-10-2-3, …)Beta Solution Treating
β
α+β
IHomogenixation
Tem
pera
ture
Time
VLow
temperature aging
β-transus
IV High
temperature aging
IIDeformation
IIISolution Treating
High temperature aging
βr → β + αcoarse
High temperature aging
βr → β + αfine
HEAT TREATMENTS OF BETA ALLOYS (3)
αgb
There’s still a continuous network of alpha phase atbeta grain boundaries but it has a pronounced weavy
shapes wit only few straight segments.
β
α+β
IHomogenixation
Tem
pera
ture
Time
β-transus
III High
temperature aging
IIDeformation
I - Beta Processing
IVLow
temperature aging
B – HIGH STRENGTH BETA ALLOYS(e.g. Ti-17, β-CEZ, Ti-10-2-3, …)
High temperature aging
βr → β + αcoarse
High temperature aging
βr → β + αfine
II – Trough Transus Processing
β
α+β
IHomogenixation
Tem
pera
ture
TimeIVLow temperature
aging
β-transus
III High
temperature aging
IIDeformation
HEAT TREATMENTS OF BETA ALLOYS (4)
αgb
(a) (b)
αgb
Through transus beta processed microstructure("necklace"): (a) as deformed; (b) after aging. There
are only globular alpha particles at beta grain boundaries.
B – HIGH STRENGTH BETA ALLOYS(e.g. Ti-17, β-CEZ, Ti-10-2-3, …)
High temperature aging
βr → β + αcoarse
High temperature aging
βr → β + αfine
β
α+β
IHomogenixation
Tem
pera
ture
Time
VLow temperature
aging
β-transus
IV High
temperature aging
IIDeformation
IIISolution Treating
III – Alpha+Beta Solution Treating
Bimodal microstructure in high strength β-CEZ after alpha+beta solution treating and aging
αp
HEAT TREATMENTS OF BETA ALLOYS (5)B – HIGH STRENGTH BETA ALLOYS
(e.g. Ti-17, β-CEZ, Ti-10-2-3, …)
High temperature aging
βr → β + αcoarse
High temperature aging
βr → β + αfine
The Lockheed SR-71 reconnaissance plane, better known as "blackbird", made up of 93% of its weight in titaniumalloys, broke some records as the fastest speed ever achieved by a piloted plane, 3.530 km/h, and the maximumheight of almost 26.000 m.More in detail, three different titanium alloys have been used: Ti-13V-11Cr-3Al (B120VCA), Ti-6Al-4V and Ti-5Al-2,5Sn.Moreover, Ti-13V-11Cr-3Al was the first β alloy to be developed although it was affected by problems ofmicrostructural instability (precipitation of Cr-rich intermetallics) beacuse of the high content of chromium.
APPLICATIONS OF BETA ALLOYS (1)AEROSPACE INDUSTRY
APPLICATIONS OF BETA ALLOYS (2)AEROSPACE INDUSTRY
707727
737747
747SP
767
757
777
0%
2%
4%
6%
8%
10%
12%
1955 1960 1965 1970 1975 1980 1985 1990 1995 2000
AIRF
RAM
E %
TIT
ANIU
M
YEAR OF INTRODUCTION
The Boing 777 aircraft was the first commercial airplane for which the volume of β alloys
outnumbered the volume of Ti-6Al-4V. The main reason was the application of the high strength metastable β alloy Ti-10-2-3 in the
landing gear structure.
Boing 777 landing gear: beta alloy Ti-10-2-3 (Ti-10V-2Fe-3Al) was used for several components saving in this way about 270 Kg.
450 500 550 600Age Temperature (°C)
900
950
1000
1050
1100
1150
1200
1250
1300
1350
1400
Ulti
mat
e Te
nsile
Str
engt
h(M
Pa)
Aging curve for Ti-10V-2Fe-3Al, solution treated at 750°C, water-quenched and aged for 8 h at indicated temperature.
APPLICATIONS OF BETA ALLOYS (3)AEROSPACE INDUSTRY
APPLICATIONS OF BETA ALLOYS (4)AEROSPACE INDUSTRY
Boing 787 main landing gear, illustrating several applications of Ti-5553 (Ti-5Al-5Mo-5V-3Cr) in the STA condition.
Heat-treatment conditions 0.2% YS (MPa)
UTS (MPa)
%EL (min)
%RA (min)
ST (Solution Treated) 800 880 15 50
STA (Solution Treated and Aged) 1170 1240 4 10
BASCA (Beta Annealed, Slow Cooled and Aged) 965 1080 6 -
Boing 787 main landing gear, illustrating several applications of Ti-5553 (Ti-5Al-5Mo-5V-3Cr) in the STA condition.
β + αgb
β + ω
β + α + ω
β + α
FC (1°C/min)
Tem
pera
ture
Time
APPLICATIONS OF BETA ALLOYS (5)AEROSPACE INDUSTRY
Cargo handling fittings used for the Boeing 777, high strength Ti-10-2-3.
Helicopter rotor using forgings of Ti-10-2-3
APPLICATIONS OF BETA ALLOYS (6)AEROSPACE INDUSTRY
Cast brake torque tube for fighter aircraft, heavy stabilized β alloy
Ti-15-3 (Ti-15V-3Cr-3Al-3Sn).
Ti-15-3 welded environmental control system duct installed on Boing 777; this beta alloy can be cold rolled in coils for the production of welded tubes.
Nut clips used in aircraft, heavy stabilized β alloy Ti-15-3.
APPLICATIONS OF BETA ALLOYS (7)AEROSPACE INDUSTRY
Aircraft springs: heavily stabilized β alloys: (a) Ti-15-3, (b,c) Beta C (Ti-3Al-8V-6Cr-4Mo-4Zr).
Comparison of landing gear actuation springs of equivalent spring constant: left—Beta C (Ti-3Al-8V-6Cr-
4Mo-4Zr) weighing 1.45 kg; right —17-4PH stainless steel weighing 4.35 kg.
APPLICATIONS OF BETA ALLOYS (8)AEROSPACE INDUSTRY
Condition UTS (MPa) 0.2% YS (MPa) Elongation %
Single aging 1034 965 6
Duplex aging 862 793 10
Typical minimum mechanical properties of Beta 21S sheet.
Usage of Beta 21S alloy (Ti-15Mo-3Al-3Nb-0,2Si) for an Exhaust Plug in a Boeing 777 Jet Engine.
Beta 21S exhaust plug
Alloy C Burn
Alloy C No Burn
Ti-6-4 Burn
Ti-6-4 No Burn
0 100 200 300 400 500 600 700Temperature (°C)
00,10,20,30,40,50,60,70,80,91,0
Pres
sure
(MPa
)
Comparative burn resistance of Alloy C (Ti-35V-15Cr) and Ti6Al4V. Burn resistance was assessed by placing a sample 1.78-mm-thick sheet having a knife edge into an air
stream flowing at 137 m/s and attempting to ignite the sample using a 200 W C02laser impinging directly on the knife edge of the sample. These test conditions
simulate those encountered in turbine engine operating conditions.
Pratt & Whitney F119 engine installed on F22 Raptor. The compressor stators and thrust-vectoring nozzle use burn-resistant titanium alloy
Ti-35V-15Cr (Alloy C), which is the only stable β alloy of practicalinterest.
APPLICATIONS OF BETA ALLOYS (8)AEROSPACE INDUSTRY
(Flow 50-120 m/s
APPLICATIONS OF BETA ALLOYS (9)BIOMEDICAL INDUSTRY
Ti - 6Al - 4VNeurologica pathologies
(e.g. Alzheimer’s desease)Toxicity realted problems (long
term cronic inflammation of tissues)
E = 110 GPa
Development of metastable beta alloy free from both aluminium and vanadium, such as Ti-29Nb-13Ta-2Sn and Ti-29Nb-13Ta-7Zr, which are particularly suitable for this application due to their hightensile and also because they have a low Youg modulus (60 -65 GPa), very close to that of the humanbones (30 GPa).
Thanks for Your attention