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Titanium Trends and Usage in Commercial Gas Turbine Engines
Jim Hansen – Materials & Processes Engineering
Jack Schirra – Advanced Programs
David Furrer, Ph.D. – Materials & Processes Engineering
2-5 October 2011
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What is the Future of Aerospace Titanium?
2
• Fuel represents ~50% Of airline costs
• Engines provide significant opportunity for fuel burn reduction
• Composite airframes also contribute to performance improvements
• Improved efficiency objectives are driving cycle and
architecture requirements challenging Ti engine usage
• Airframe applications driven by composite compatibility
promoting Ti usage
Ti research focus – affordability then performance
…is it the right balance?
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Outline
Historic Titanium Usage
Trends in Engine Architecture & Cycle
Impact to Material Usage
The Challenge - Material Requirements for
Next Generation Engines
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Page 4
Historic Titanium Usage
Alpha Case
(time dependent)
Ti Fire
(pressure dependent)
Adapted from ”Developments in High Temperature Titanium Alloys”
Blenkinsop, P.A. Titanium Science & Technology 1984
300
350
400
450
500
550
600
650
700
1940 1950 1960 1970 1980 1990 2000
Max
Te
mp
era
ture
-°C
Year of Introduction
Ti 6-4
Ti 17
Ti 6-2-4-2-S
IMI 834
Ti 6-2-4-2
IMI 829
IMI 550
Ti 8-1-1
IMI 679
IMI 685
Ti 48-2-2
Ti 6-2-4-6
PW Alloy C
Titanium historically limited by Alpha Case and compressor fire potential (& cost)
4 ECCN EAR99
Page 5
Titanium Usage – Last Century
PW 4000 materials of construction • Titanium ~25% by weight
Fan Low
Pressure
Compressor
High
Pressure
Compressor
Ti
Fir
e
Lin
e
5
0
5
10
15
20
25
30
1950 1960 1970 1980 1990 2000 2010
Year
Perc
en
t o
f S
yste
m W
eig
ht
777
757 & 767
747
737
727707
J57
PW2037
PW4056
PW4084 PW6000
ECCN EAR99
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Engine Efficiency Drivers
• Propulsive efficiency: Driven by increased bypass ratio
• Higher bypass ratio larger diameter fan
• To maximize benefits of a large fan:
• Need hollow titanium or composite fan blades
• Need light weight composite static structure
• Cycle efficiency: Driven by higher pressure ratio and
higher turbine inlet temperature
• Higher pressure ratios require higher temperature
capability in the high pressure compressor
• Higher turbine inlet temperatures require higher
temperature turbine materials and coatings.
Overall efficiency = Propulsive efficiency x Cycle efficiency
bypass airflow
bypass airflow
Fan
Conventional Turbofan
Compressor
Low High
Turbine
High Low
Bypass Ratio = Bypass Airflow / Core Airflow
6 ECCN EAR99
www.pw.utc.com
Page 7
Bypass Ratio Drives Efficiency & Noise As bypass ratios increases
- Thrust Specific Fuel Consumption (TSFC) and noise decrease
Gas Turbine Technology Evolution: A Designer’s Perspective
Bernard L. Koff
TurboVision, Inc., Palm Beach Gardens, Florida 33418
JOURNAL OF PROPULSION AND POWER
Vol. 20, No. 4, July–August 2004
7
2006 Requirement
Stage 4 10dB
below Stage 3
EPNdb – Expected
Perceived Noise Level
ECCN EAR99
Page 8
Whittle
Von Chain
J57J52
JT3D
J79
JT8D TF30
F100
F100CF6-50
JT9D-7R4
F404
2037
CF6-80
4056V25004060
41684084
GE90
Trent
0
5
10
15
20
25
30
35
40
45
1930 1940 1950 1960 1970 1980 1990 2000 2010
Co
mp
res
so
r P
res
su
re R
ati
o
Year
sea level static,
standard day
Compressor Temperature Trend
Increasing
Temperature
Gas Turbine Technology Evolution: A Designer’s Perspective
Bernard L. Koff
TurboVision, Inc., Palm Beach Gardens, Florida 33418
JOURNAL OF PROPULSION AND POWER
Vol. 20, No. 4, July–August 2004
Engine efficiency increases as compressor pressure ratios increase.
Compressor temperature increases with pressure.
“As the operating
temperature of turbine
engines increases,
titanium will struggle to
maintain its foothold in
aircraft high pressure
compressor disks.”
- G.Vroman, Sr. VP, ATI-
Ladish, from American
Metal Market,1998
8 ECCN EAR99
Page 9
Engine Changes – Material Impacts
Engine architecture and cycles driving material changes away from titanium:
• Bypass Ratios Increasing = Larger Diameter Fans
• Organic matrix composites (OMCs) replacing Ti in fan blades and containment
cases
• Compressor pressure ratios increasing = Hotter compressors and turbines
• Transition to integrally bladed rotors results in material selected by gas path
requirements
• Nickel replacing titanium in earlier stages of the high pressure compressor
(HPC)
• High temperature turbines reduce stages where gamma alloys work
• Core diameters are decreasing
• The volume (size) of Ti & Ni components is decreasing
9
ECCN EAR99
Page 10
Bypass Ratio & Fan Blade Materials
Materials play a key role in enabling higher bypass ratios by enabling larger
diameter light weight fans.
1960 - 1980s
Solid Ti
1990s
Hollow Ti
2000s
Composite
PW 1524G
BPR = 12
GE 90
BPR = 9 PW 4084
BPR = 6.4
JT3D
BPR = 1.3
2010s
Composite / Hybrid Metallic
10 ECCN EAR99
Page 11
Bypass Ratio & Fan Case Materials
PW 4056
BPR = 4.8
Solid Steel
V2500
BPR = 4.5 - 5.4
Solid Titanium
Solid steel and titanium fan containment cases being replaced by Kevlar
composite and all composite designs to reduce weight.
GP7200
BPR = 8.8
Kevlar/Aluminum
PW1524G
BPR = 12
Composite
1980s
1990s
2000s
2010s
11 ECCN EAR99
Page 12
Engine Changes
Fan Blades
Ti to Composite/Hybrid Metallic
(Ti leading edge sheaths)
SGV
Ti to Composite/Aluminum
HPC Rotors & Stators
Ti to Nickel
HPC Rotors & Stators
Gamma potential
Larg
er
Dia
mete
r F
an
s
Smaller Diameter,
Higher Pressure &
Hotter Cores
LPC Rotors & Stators
Ti to Composite/Aluminum
Engine architecture/cycle drives material changes
LPT Blades
Ni to Gamma Ti
12 ECCN EAR99
Page 13
Titanium Usage – This Century
Commercial aircraft and engines
• Temperature limitations – Ceiling for utilization in engines
• New engines - Higher bypass ratios, smaller cores, increased
temperature / larger Fans reduced Ti content
13
0
5
10
15
20
25
30
1950 1960 1970 1980 1990 2000 2010 2020
Perc
en
t o
f S
yste
m W
eig
ht
Year
787
777
757 & 767
747
737
727707
J57
PW2037
PW4056
PW4084 PW6000
PW GTF
ECCN EAR99
Page 14
Ti Development Challenges…From an Engine Perspective
Aluminum
OMC - BMI
Titanium
OMC - Polyimides
Gamma Ti
Nickel / Cobalt
Alpha Case
Burn Resistance
1100
1000
900
800
700
600
500
400
300
200
100
°C
Max use temperature
• Cost (always of great interest)
− Compete with Al & steel
• High specific capability (propulsive efficiency)
− Compete with composites
• Environmental resistance (thermal efficiency)
− Compete with superalloys
Structural Composite Materials, Chapter 1
F.C. Campbell, 2010, ASM International 14
$
ECCN EAR99
Page 15
Airframe Technology Examples
Aluminum industry’s response to composites: increase performance
• High strength corrosion resistant alloys
• Increased strength & design compatible
• 3rd Generation Al-Li alloys
• Increased specific strength & stiffness
• Novel manufacturing methods (FSW)
• Hybrid materials (GLARE)
• GLARE® (GLAss fiber REinforced aluminum)
Similar advances/approach required for Titanium
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Page 16
Next Generation Engine Opportunities
• Fan & LPC - Specific strength vs. OMCs
• Cost Effective MMCs, Ti + B (P/M), Hybrid Ti / OMCs
• HPC - Temperature capability and burn resistance
• Higher Temperature Capable & Burn Resistant Alloys and Coatings,
Expanded Use of Gamma Ti
• LPT - Creep and oxidation (Gamma Ti)
• Higher Temperature Capable Alloys / Coatings
• Low cost material and manufacturing processes
• Low Cost Raw Materials – Ti Reduction, Melting, Conversion
• Additive Manufacturing to Enable Hybrid & Low Cost Solutions
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Page 17
Summary
• Titanium usage decreasing in engine applications
• Driven by cycle and architecture changes
• Displaced by organic matrix composites and super alloys
• Aluminum industry response to composite threat is increased
performance / advanced fabrication technologies
• Technology opportunities for Titanium
• Increased specific capability
• Advanced manufacturing for high performance structures
• Improved temperature capability systems (coatings)
• Continued work on cost reduction
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Page 18
18 QUESTIONS ?
Thank You
0
5
10
15
20
25
30
1950 1960 1970 1980 1990 2000 2010 2020
Perc
en
t o
f S
yste
m W
eig
ht
Year
787
777
757 & 767
747
737
727707
J57
PW2037
PW4056
PW4084 PW6000
PW GTF
ECCN EAR99