heat treatments and applications of titanium alloys · 2020. 12. 10. · vacuum heat treatments,...

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

Relatore

Note di presentazione

Cover

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.

Relatore


CONTENT PAGE 01

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


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


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)


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)


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


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.


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


α basketweave

Beta AnnealingA – SLOW/MODERATE COOLING RATES

Beta Annealing


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.


1 – Precipitation of Ti3Al in α 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.




STABILIZATION

β

α+β

IHomogenixation

Tem

pera

ture

Time

β-transus

IV Stabilization

IIDeformation

IIIAlpha + Beta

Annealing

Alpha+Beta Annealing (C)


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


STABILIZATION

Beta Annealing

Fully LamellarMicrostructure

High Temperature Range

Alpha + Beta Annealing

Low Temperature Range

BimodalMicrostructure

Fine EquiaxedGrains

Coarse EquiaxedGrains


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


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


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.


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.


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).


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


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


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


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.


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.


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).


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

Relatore


In automotive industry, titanium is used in critical applications, where the demand for extreme performance actually overcomes the problem of cost reducing. In fact, for many years titanium has been used for parts of Formula One cars and, more generally, for parts of racing engines. In production cars, although interesting, the use of titanium alloys is often forbidden by their high cost: frequently the cost of raw material is just close to the price of the finished component.

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



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.



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

Relatore


With alloy IMI 834, near alpha alloys have probably reached their maximum development

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


High temperature aging

βr → β + αcoarse


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, …)




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, …)




βr → β + αfine

β

α+β

IHomogenixation

Tem

pera

ture

Time

VLow temperature

aging

β-transus

IV High

temperature aging

IIDeformation


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, …)




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


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.



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


Cargo handling fittings used for the Boeing 777, high strength Ti-10-2-3.

Helicopter rotor using forgings of Ti-10-2-3

Relatore


Cargo handling fittings = accesso movimentazione del carico Mast = albero Sleeve = manicotto


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.

Relatore


Duct = condotto Nut clip = fermadadi


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.

Relatore


Cargo handling fittings = accesso movimentazione del carico Mast = albero Sleeve = manicotto


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.


(Flow 50-120 m/s

Relatore


Thrust-vectoring nozzle = ugello spinta vettoriale Oxidation of titanium is strongly exothermic but, unlike magnesium, it’s not self sustaining in air at atmospeheric pressure and oxygen partial pressure. This reaction needs elevated temperature, pressure and high mass flow conditions like in compressors, whre the trigger event may be the contact between a rotating part and a titanium case.

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

heat treatments and applications of titanium alloys · 2020. 12. 10. · vacuum heat treatments,...

Documents