Titanium 6-6-2 (3.7175, R56620)
Titanium 6-6-2 is a titanium alloy formulated for primary forming into wrought products. 3.7175 is the EN numeric designation for this material. R56620 is the UNS number. And Titanium 6-6-2 is the common industry name.
It has the lowest embodied energy among wrought titaniums. In addition, it can have a fairly high tensile strength and has a moderately low thermal conductivity.
The properties of titanium 6-6-2 include two common variations. This page shows summary ranges across both of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare titanium 6-6-2 to: wrought titaniums (top), all titanium alloys (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.
Mechanical Properties
Elastic (Young's, Tensile) Modulus
120 GPa 17 x 106 psi
Elongation at Break
6.7 to 9.0 %
Fatigue Strength
590 to 670 MPa 85 to 97 x 103 psi
Poisson's Ratio
0.32
Reduction in Area
17 to 23 %
Shear Modulus
44 GPa 6.3 x 106 psi
Shear Strength
670 to 800 MPa 98 to 120 x 103 psi
Tensile Strength: Ultimate (UTS)
1140 to 1370 MPa 170 to 200 x 103 psi
Tensile Strength: Yield (Proof)
1040 to 1230 MPa 150 to 180 x 103 psi
Thermal Properties
Latent Heat of Fusion
400 J/g
Maximum Temperature: Mechanical
310 °C 580 °F
Melting Completion (Liquidus)
1610 °C 2920 °F
Melting Onset (Solidus)
1560 °C 2830 °F
Specific Heat Capacity
540 J/kg-K 0.13 BTU/lb-°F
Thermal Conductivity
5.5 W/m-K 3.2 BTU/h-ft-°F
Thermal Expansion
9.4 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
1.1 % IACS
Electrical Conductivity: Equal Weight (Specific)
2.1 % IACS
Otherwise Unclassified Properties
Base Metal Price
40 % relative
Density
4.8 g/cm3 300 lb/ft3
Embodied Carbon
29 kg CO2/kg material
Embodied Energy
470 MJ/kg 200 x 103 BTU/lb
Embodied Water
200 L/kg 24 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
89 to 99 MJ/m3
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
34 points
Strength to Weight: Axial
66 to 79 points
Strength to Weight: Bending
50 to 57 points
Thermal Diffusivity
2.1 mm2/s
Thermal Shock Resistance
75 to 90 points
Alloy Composition
| Ti | 82.8 to 87.8 | |
| Mo | 5.0 to 6.0 | |
| Al | 5.0 to 6.0 | |
| Sn | 1.5 to 2.5 | |
| Fe | 0.35 to 1.0 | |
| Cu | 0.35 to 1.0 | |
| O | 0 to 0.2 | |
| C | 0 to 0.050 | |
| N | 0 to 0.040 | |
| H | 0 to 0.015 | |
| res. | 0 to 0.4 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
Titanium and Titanium Alloys: Fundamentals and Applications, Christoph Leyens and Manfred Peters (editors), 2003
Titanium, 2nd ed., G. Lutjering and J. C. Williams, 2007
CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015