titanium alloys - universidad de sevilla
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TITANIUM ALLOYS
Master GSC & AIO 2011-2012
GLOBAL SUPPLY CHAIN & AERONATICAL INDUSTRIAL OPERATIONS
Module 2: Metallic materials in the manufacturing of aircraft
Titanium alloys were developed
in the early 50's due to their high
strength / density rate, for use in
aerospace applications. Today
are about 15% of the structure..
Slat of EF-2000
Titanium alloys are used in aerospace for its excellent
combination of features:
-good mechanical properties (up to 1400 MPa)
-low-density (are 40% lighter than steel and 60% heavier than
aluminum)
-excellent corrosion resistance and electrochemical compatibility
with CFRC
- can compete, at equal weight, with steel as high as 2100Mpa,
and its resistance to corrosion is much better
-compared with aluminum alloys, are much more resilient, have
better behavior at high temperatures and have better fatigue
resistance and toughness at these temperatures.
There are many other properties of titanium alloys that allow
specific applications: low coefficient of thermal expansion, good
oxidation resistance at intermediate temperatures, good
toughness, etc ...
TITANIUM ALLOYS
Master GSC & AIO 2011-2012
GLOBAL SUPPLY CHAIN & AERONATICAL INDUSTRIAL OPERATIONS
Module 2: Metallic materials in the manufacturing of aircraft
TITANIUM ALLOYS
The allotropic forms of titanium are two:
-alpha: hexagonal close-packed HCP crystal structure
-beta: body centered cubic BCC crystal structure
Master GSC & AIO 2011-2012
GLOBAL SUPPLY CHAIN & AERONATICAL INDUSTRIAL OPERATIONS
Module 2: Metallic materials in the manufacturing of aircraft
TITANIUM ALLOYS
-The alpha crystal structure of hexagonal close-packed atoms (HCP)
is stable at room temperature in pure titanium to about 882 ° C, that is
transformed into a body centered cubic structure (BCC) called beta,
which is stable until the melting point (1670 ° C).
-The alloying elements stabilize one stage or another:
-alpha-stabilizers: Al, C, O, N (increasing the stability of
the alpha phase above the beta transformation point)
-beta-stabilizers: Cu, Cr, Fe, Mo, V (down their
transformation temperature, allowing the beta structure to
be stable at lower temperatures, even at room temperature)
-The mechanical properties of Ti alloys are closely related to these
allotropic forms, because the beta (BCC structure) is much stronger
but more brittle than the alpha (HCP).
Master GSC & AIO 2011-2012
GLOBAL SUPPLY CHAIN & AERONATICAL INDUSTRIAL OPERATIONS
Module 2: Metallic materials in the manufacturing of aircraft
TITANIUM ALLOYS
Master GSC & AIO 2011-2012
GLOBAL SUPPLY CHAIN & AERONATICAL INDUSTRIAL OPERATIONS
Module 2: Metallic materials in the manufacturing of aircraft
TITANIUM ALLOYS
Ti alloys are classified into three types according to the
predominant crystalline structure:
-alpha-alloys or "near" alpha
-beta-type alloys
-alpha-beta-alloys
The alpha type are employed in applications where corrosion
resistance is the most desired quality, the remainder being
developed for aerospace applications and are a mixture of
alpha and beta phases and in general to heat treatable
achieving high levels of mechanical strength.
The most used is the Ti6Al4V.
Master GSC & AIO 2011-2012
GLOBAL SUPPLY CHAIN & AERONATICAL INDUSTRIAL OPERATIONS
Module 2: Metallic materials in the manufacturing of aircraft
TITANIUM ALLOYS
Master GSC & AIO 2011-2012
GLOBAL SUPPLY CHAIN & AERONATICAL INDUSTRIAL OPERATIONS
Module 2: Metallic materials in the manufacturing of aircraft
TITANIUM ALLOYS
The new beta alloys type Ti-5553 or TIMETAL 555 (Ti-5Al-5V-
5Mo-0.6Fe-3CR) can be heat treated to levels similar to those of
high strength steels (1240 MPa) much higher than the typical
Ti6Al4V, with improved damage resistance but are difficult to
machine.
Master GSC & AIO 2011-2012
GLOBAL SUPPLY CHAIN & AERONATICAL INDUSTRIAL OPERATIONS
Module 2: Metallic materials in the manufacturing of aircraft
TITANIUM ALLOYS
Partial phase diagram of the Ti-6Al-
V system and the schematic
representación of microstructures
resulting from the fabrication of Ti-
6Al-V alloy at various temperatures.
Master GSC & AIO 2011-2012
GLOBAL SUPPLY CHAIN & AERONATICAL INDUSTRIAL OPERATIONS
Module 2: Metallic materials in the manufacturing of aircraft
TITANIUM ALLOYS
Titanium alloys most widely used in aircraft manufacture are the alpha-beta, particularly Ti6Al4V:
-is around 50% of total world production of Ti and Ti alloys
-more frequent used in the annealed condition (896 MPa)
Master GSC & AIO 2011-2012
GLOBAL SUPPLY CHAIN & AERONATICAL INDUSTRIAL OPERATIONS
Module 2: Metallic materials in the manufacturing of aircraft
TITANIUM ALLOYS
Ti-8AL-1Mo-1V microstructures.
β α -β
Master GSC & AIO 2011-2012
GLOBAL SUPPLY CHAIN & AERONATICAL INDUSTRIAL OPERATIONS
Module 2: Metallic materials in the manufacturing of aircraft
TITANIUM ALLOYS
β-Titanium Alloy Ti-555 microstructures
Master GSC & AIO 2011-2012
GLOBAL SUPPLY CHAIN & AERONATICAL INDUSTRIAL OPERATIONS
Module 2: Metallic materials in the manufacturing of aircraft
TITANIUM ALLOYS
Manufacturing characteristics of titanium alloys:
-electrochemical compatibility with CFRC
-improvement of fatigue strength by stress relief heat treatments
and surface shot-peening
-must be taken precautions during surface treatments to prevent
the absorption of hydrogen and chloride contamination
-forming must be conducted by hot-forming or superplastic
forming
-exist titanium based alloys with shape memory
Master GSC & AIO 2011-2012
GLOBAL SUPPLY CHAIN & AERONATICAL INDUSTRIAL OPERATIONS
Module 2: Metallic materials in the manufacturing of aircraft
TITANIUM ALLOYS
Shot peening
Master GSC & AIO 2011-2012
GLOBAL SUPPLY CHAIN & AERONATICAL INDUSTRIAL OPERATIONS
Module 2: Metallic materials in the manufacturing of aircraft
TITANIUM ALLOYS
Hydrogen and oxigen contamination
Master GSC & AIO 2011-2012
GLOBAL SUPPLY CHAIN & AERONATICAL INDUSTRIAL OPERATIONS
Module 2: Metallic materials in the manufacturing of aircraft
TITANIUM ALLOYS
Stress corrosion cracking
Master GSC & AIO 2011-2012
GLOBAL SUPPLY CHAIN & AERONATICAL INDUSTRIAL OPERATIONS
Module 2: Metallic materials in the manufacturing of aircraft
TITANIUM ALLOYS
Forming must be conducted by hot-forming or superplastic
D-NOSES HTP LEADING EDGE A330
Master GSC & AIO 2011-2012
GLOBAL SUPPLY CHAIN & AERONATICAL INDUSTRIAL OPERATIONS
Module 2: Metallic materials in the manufacturing of aircraft
TITANIUM ALLOYS
The shape memory alloys or SMA are a special class of alloys of titanium and nickel
showing the ability to return to a previously defined shape or size when subjected to the
appropriate thermal process. Generally, these materials can be plastically deformed at a
relatively low temperature and then exposing them to higher temperatures, they return to
their shape or size prior to deformation.
Master GSC & AIO 2011-2012
GLOBAL SUPPLY CHAIN & AERONATICAL INDUSTRIAL OPERATIONS
Module 2: Metallic materials in the manufacturing of aircraft
Master GSC & AIO 2011-2012
GLOBAL SUPPLY CHAIN & AERONATICAL INDUSTRIAL OPERATIONS
Module 2: Metallic materials in the manufacturing of aircraft
1.-Properties and Selection: Irons, Steels, and High-Performance
Alloys.ASM Handbook.volume 01, 1Oth Edition.
2.-Properties and Selection: Nonferrous Alloys and Special-Purpose
Materials.ASM Handbook.volume 02, 1Oth Edition.
3.-Airframe Structural Design.M.Chung.8th Edition.1995.Commilit
Press.
4.-MIT Open Course.Structural Mechanics.Aeronautics.2002.
5.-Structural Elements Design Manual.T.Draycot.1999.
REFERENCES
Master GSC & AIO 2011-2012
GLOBAL SUPPLY CHAIN & AERONATICAL INDUSTRIAL OPERATIONS
Module 2: Metallic materials in the manufacturing of aircraft