|
 Ti6Al4V, also known as grade 5, Ti-6Al-4V or Ti 6-4, is
the most commonly used titanium alloy. It has a chemical composition of
6% aluminum, 4% vanadium, 0.25% (maximum) iron, 0.2% (maximum)
oxygen,
and the remainder titanium. It is significantly stronger than
commercially pure titanium while having the same stiffness and
thermal properties (excluding thermal conductivity, which is
about 60% lower in Grade 5 Ti than in CP Ti). Among its many
advantages, it is heat treatable. This grade is an excellent
combination of strength, corrosion resistance, weld and fabric
ability. This alpha-beta alloy is the workhorse alloy of the
titanium industry. The alloy is fully heat treatable in
section sizes up to 15mm and is used up to approximately 400°C
(750°F). Over 70% of all alloy grades melted are a sub-grade
of Ti6Al4V, its uses vary in many aerospace airframe and
engine component uses and also major non-aerospace
applications in the marine, offshore and power generation
industries in particular.
Generally, Ti-6Al-4V is used in applications up to 400 degrees
Celsius. It has a
density
of roughly 4420 kg/m3,
Young's
modulus
of 110 GPa, and
tensile
strength
of 1000 Mpa. By comparison, annealed type 316 stainless steel
has a density of 8000 kg/m3, modulus of 193 GPa,
and tensile strength of only 570 Mpa. While tempered
6061
aluminum alloy
has 2700 kg/m3, 69 GPa, and 310 MPa, respectively.
 Mill anneal 1300-1450°F 2 hours, air cool. Re-crystallization
anneal bar for better ductility and fatigue strength, 1750°F 2
hours, furnace cool. For maximum fracture toughness and stress
corrosion cracking resistance (SCC), Beta anneal 1950°F 1-2
hours, water quench. Then age 1150-1300°F 2 to 4 hours, air
cool. For maximum strength, solution-treated and aged (STA)
condition is: For sheet, 1675-1725°F 5 to 25 minutes, water
quench. Age 975°F 4 to 6 hours, air cool. For bars and
forgings, 1675-1725°F 1 hour, water quench. Age 975-1025°F 3
hours, air cool. For increased fracture toughness, but lower
tensile strength, precipitation treat (overage) 1150-1250°F 4
hours, air cool. Stress relief annealing is commonly
1000-1200°F 1 to 4 hours, air cool.
Ti 6Al-4V is susceptible to chloride (SCC), although being
among the better of the titanium alloys in this regard. For
marine environments silver plated bolts are not used, as
silver bonds easily with chlorine in this environment. Ti
6Al-4V is also susceptible to SCC in environments such as
methyl alcohol, red fuming HNO3, and N2O4.
In the case of red fuming nitric acid, the problem is limited
to environments containing less than 1.5% water, or more than
6% NO2. Failure in N2O4 has
occurred when oxygen and chlorides were present as impurities.
Ti-6Al-4V is the alloy most commonly used in wrought and cast
forms. Palladium or ruthenium can be added for increased
corrosion resistance. Most properties are affected by the
microstructure, which is determined by the thermo-mechanical
history. It is highly resistant to general corrosion in sea
water. This alloy is available in most common product forms
including billet, bar, wire, plate, and sheet.
Ti-6Al-4V has Excellent biocompatibility, especially when
direct contact with tissue or bone is required. Ti-6Al-4V's
poor shear strength makes it undesirable for bone screws or
plates. It also has poor surface wear properties and tends to
seize when in sliding contact with itself and other metals.
Surface treatments such as nitriding and oxidizing can improve
the surface wear properties.
Chemistry Components
|
|
Al |
V |
C |
N |
O |
H |
Fe |
Y |
Others
Each |
Ti |
|
MIN |
5.5 |
3.5 |
_ |
_ |
_ |
_ |
_ |
_ |
_ |
_ |
|
MAX |
6.75 |
4.5 |
0.08 |
0.5 |
0.2 |
0.0125 |
0.3 |
0.005 |
0.1 |
Balance |
Applications
|
• |
Blades, Rings, and Discs |
|
• |
Sporting Equipment |
|
• |
Aircraft Structural Components |
|
• |
Hand
Tools |
|
• |
Airframes |
|
• |
Fasteners, Components |
|
• |
Vessels, Cases, Hubs, Forgings |
|
• |
Biomedical Implants |
Inventory
|
• |
Forged Billet |
|
• |
Sheet |
|
• |
Plate |
|
• |
Rectangular Bar |
|
• |
Bar |
Specifications
|
•
|
AMS 4911, AMS 4920, AMS 4928, AMS 4934, AMS 4935, AMS
4965, AMS 4967, AMS 6930, AMS 6931, AMS T-9046, AMS
T-9047
ASME SB 348, ASME SB 861, ASME SB-265 Grade 5
ASTM B 265, ASTM B 348, ASTM B 381, ASTM B 861, ASTM F
1472
EN 3.7164, EN 3.7165
MIL-T-9046, MIL-T-9047
UNS R56400
Werkstoff 3.7164, Werkstoff 3.7165 |
| |
|
|
Physical Properties |
Metric |
English |
Comments |
|
|
|
Density |
4.43 g/cc |
0.16 lb/in³ |
|
|
Mechanical Properties |
|
|
|
Hardness, Brinell |
334 |
334 |
Estimated from Rockwell C. |
|
Hardness, Knoop |
363 |
363 |
Estimated from Rockwell C. |
|
Hardness, Rockwell C |
36 |
36 |
|
|
Hardness, Vickers |
349 |
349 |
Estimated from Rockwell C. |
|
Tensile Strength, Ultimate |
950 MPa |
138000 psi |
|
|
Tensile Strength, Yield |
880 MPa |
128000 psi |
|
|
Elongation at Break |
14 % |
14 % |
|
|
Reduction of Area |
36 % |
36 % |
|
|
Modulus of Elasticity |
113.8 GPa |
16500 ksi |
|
|
Compressive Yield Strength |
970 MPa |
141000 psi |
|
|
Notched Tensile Strength |
1450 MPa |
210000 psi |
Kt (stress concentration factor) = 6.7 |
|
Ultimate Bearing Strength |
1860 MPa |
270000 psi |
e/D = 2 |
|
Bearing Yield Strength |
1480 MPa |
215000 psi |
e/D = 2 |
|
Poisson's Ratio |
0.342 |
0.342 |
|
|
Charpy Impact |
17 J |
12.5 ft-lb |
V-notch |
|
Fatigue Strength |
240 MPa |
34800 psi |
at 1E+7 cycles. Kt (stress concentration
factor) = 3.3 |
|
Fatigue Strength |
510 MPa |
74000 psi |
Unnotched 10,000,000 Cycles |
|
Fracture Toughness |
75 MPa-m½ |
68.3 ksi-in½ |
|
|
Shear Modulus |
44 GPa |
6380 ksi |
|
|
Shear Strength |
550 MPa |
79800 psi |
Ultimate shear strength |
|
Electrical Properties |
|
|
|
Electrical Resistivity |
0.000178 ohm-cm |
0.000178 ohm-cm |
|
|
Magnetic Permeability |
1.00005 |
1.00005 |
at 1.6kA/m |
|
Magnetic Susceptibility |
3.3e-006 |
3.3e-006 |
cgs/g |
|
Thermal Properties |
|
|
|
CTE, linear 20°C |
8.6 µm/m-°C |
4.78 µin/in-°F |
20-100ºC |
|
CTE, linear 250°C |
9.2 µm/m-°C |
5.11 µin/in-°F |
Average over the range 20-315ºC |
|
CTE, linear 500°C |
9.7 µm/m-°C |
5.39 µin/in-°F |
Average over the range 20-650ºC |
|
Specific Heat Capacity |
0.5263 J/g-°C |
0.126 BTU/lb-°F |
|
|
Thermal Conductivity |
6.7 W/m-K |
46.5 BTU-in/hr-ft²-°F |
|
|
Melting Point |
1604 - 1660 °C |
2920 - 3020 °F |
|
|
Solidus |
1604 °C |
2920 °F |
|
|
Liquidus |
1660 °C |
3020 °F |
|
|
Beta Transus |
980 °C |
1800 °F |
|
|
