Guides/Comparisons
Titanium vs aluminium
titanium-vs-aluminiumTitanium and Aluminium at a glance
This page compares Titanium and Aluminium using only values that carry a source, a test condition and an evidence level. Ranges run across temper, heat treatment and product form, measured at room temperature where the source says so.
- Yield strength: the ranges overlap (Titanium 138 to 1,282 MPa; Aluminium 29 to 510 MPa).
- Tensile strength: the ranges overlap (Titanium 240 to 1,300 MPa; Aluminium 60 to 572 MPa).
- Density: Titanium is higher (Titanium 3.8 to 8.3 g/cm³; Aluminium 2.65 to 2.84 g/cm³), about 2.2 times the midpoint of Aluminium.
- Young's modulus: Titanium is higher (Titanium 82 to 207 GPa; Aluminium 57.2 to 79 GPa), about 2.1 times the midpoint of Aluminium.
- Thermal conductivity: Aluminium is higher (Titanium 0.71 to 22 W/(m·K); Aluminium 120 to 229 W/(m·K)), about 15.4 times the midpoint of Titanium.
- Melting point: Titanium is higher (Titanium 1,604 to 1,670 °C; Aluminium 490 to 660 °C), about 2.8 times the midpoint of Aluminium.
- Service temperature: Titanium is higher (Titanium 288 to 540 °C; Aluminium 65 to 160 °C), about 3.7 times the midpoint of Aluminium.
- Thermal expansion: Aluminium is higher (Titanium 8.6 to 9.7 ppm/K; Aluminium 21.4 to 25 ppm/K), about 2.5 times the midpoint of Titanium.
- Yield strength for each unit of density (calculated from each grade's midpoint values): Titanium 49.7 to 229 MPa per g/cm³; Aluminium 10.7 to 180 MPa per g/cm³.
"Higher" means the whole range is higher, not just one value. Where a value is a specified minimum, the table says "at least".
Side by side
| Property | Titanium | Aluminium |
|---|---|---|
| Yield strength | 138 to 1,282 MPa | 29 to 510 MPa |
| Tensile strength | 240 to 1,300 MPa | 60 to 572 MPa |
| Density | 3.8 to 8.3 g/cm³ | 2.65 to 2.84 g/cm³ |
| Young's modulus | 82 to 207 GPa | 57.2 to 79 GPa |
| Thermal conductivity | 0.71 to 22 W/(m·K) | 120 to 229 W/(m·K) |
| Melting point | 1,604 to 1,670 °C | 490 to 660 °C |
| Service temperature | 288 to 540 °C | 65 to 160 °C |
| Thermal expansion | 8.6 to 9.7 ppm/K | 21.4 to 25 ppm/K |
| Yield strength per densitycalculated | 49.7 to 229 MPa per g/cm³ | 10.7 to 180 MPa per g/cm³ |
When to use which
| Material | Best for | Weakest at |
|---|---|---|
| Commercially pure titanium, Grade 2 (UNS R50400) | Seawater, brine and chloride service where corrosion resistance and formability matter more than strength (Alleima and Smiths datasheets) | Strength: 345 MPa minimum tensile, well below Ti-6Al-4V (see the Ti-6Al-4V profile). Crevice attack in hot seawater from about 80 °C (Pang and Blackwood 2016) |
| Ti-6Al-4V | Strength-to-weight structures that must stay strong up to about 400 degC, such as aerospace forgings and bars (the datasheet gives 4.43 g/cm3 density and 830 to 950 MPa yield) | Low thermal conductivity (6.7 W/(m K) at 20 degC), and lower ductility once it is solution-treated and aged (6 to 10 % elongation) |
| Titanium alloy Ti-6Al-4V ELI (Grade 23) | Cold-service hardware and medical implants where toughness and low interstitial content matter (Carpenter; UPMET; Titanium Industries). | Thermal conduction: 6.6 W/(m K) at 20 degC is low for a metal (UPMET). The sources read give no room-temperature fracture toughness for commercial bar. |
| Titanium Grade 9, Ti-3Al-2.5V (UNS R56320) | Seamless hydraulic and fluid tube, corrosion-resistant pipe and sporting frames, where more strength than commercially pure titanium is needed with more formability than Grade 5 (Smiths datasheets, Bibus) | Strength below Grade 5: 620 MPa minimum tensile when annealed, against 895 MPa for Grade 5 (ASTM B265). No thermal, cryogenic or space data for this grade were read in this run. |
| TiAl | Light rotating parts that run hot, such as low-pressure turbine blades in GE engines, where a density near 3.8 g/cm3 and a stiffness of 168 GPa matter more than ductility | Room-temperature ductility, since cast Ti-48-2-2 elongates only 1.70 % at 23 degC and impact can crack thin sections |
| Beta 3 | Parts that are cold formed in the solution-treated state and then aged to high strength, such as TIMETAL 15-3 strip (1000 MPa minimum tensile after 8 h at 538 degC) | Ductility after ageing (TIMETAL 15-3 strip falls to 5 to 7 % elongation), and the Beta 3 strength data are missing from the sources read |
| Commercially pure titanium with palladium, Grade 11 (UNS R52250) | Chloride and reducing-acid chemical plant equipment, and desalination or marine service, where crevice corrosion resistance matters more than strength (S+D Metals and Elgiloy datasheets) | Strength: 240 MPa minimum tensile, below the 345 MPa minimum of Grade 2 (ASTM B265). No Grade 11 crevice-corrosion test temperature was found in the sources read for this profile |
| Commercially pure titanium, Grade 3 (UNS R50550) | Formed and welded parts that need more strength than Grade 2 while keeping weldability and corrosion resistance in oxidising, neutral and mildly reducing media (Smiths) | Strength: 450 MPa minimum tensile, well below Ti-6Al-4V (see the Ti-6Al-4V profile). Oxygen limit of 0.35 %, the highest of CP grades 1 to 3 in ASTM B265 Table 2 |
| Commercially pure titanium, Grade 7 | Chemical processing and hot chloride or acid service where crevice corrosion is the main concern and Grade 2 is not enough (ATI corrosion data sheet; Elgiloy datasheet) | Strength: 345 MPa minimum tensile, the same as Grade 2 and well below Ti-6Al-4V. Its crevice limit depends on pH and temperature, and no Grade 7 test at pH 1 or below was read in this run |
| Minor titanium alloys, Ti-Mo, Ti-V, Ti-Fe, Ti-Si | Ti-10V-2Fe-3Al for forged, heat-treated structural parts that must hold about 1000 N/mm2 tensile strength at room temperature and about 900 N/mm2 at 315 degC | Ti-Mo binaries lose ductility when aged or cast (Ti-15.05Mo falls to 6.95 % elongation after solution treatment), and Ti-Ga, Ti-Si and Ti-V have no alloy-level property value in the sources read |
| Aluminium alloy 6061 | A light, workable structural metal with good corrosion resistance (the NASA handbook ranks 6061 best of the heat-treatable aluminium alloys for corrosion) | Galvanic attack when coupled to more noble metals, especially in sea water (NASA handbook); typical strength values are marked not for design |
| Aluminium alloy 7075-T6 | High-strength aluminium parts where low mass and wrought forms such as tube, plate, bar or forging are useful | Stress-corrosion cracking in the short-transverse direction in T6, and relatively poor corrosion resistance in industrial and marine environments |
| Aluminium alloy 2024 | A high-strength wrought aluminium alloy for aircraft fittings and structural parts (the datasheets list these uses; ASM typical T4 yield strength is 324 MPa) | Stress-corrosion cracking of the 2024-T351 temper in seacoast and salt-water conditions (NASA 1981), and pitting in salt water |
| Aluminium alloy 5052 | Welded sheet and tank or marine-style parts at medium strength, where the temper is named and checked (the datasheets rate its seawater resistance very good) | Strength depends on temper (yield 13 ksi annealed to 37 ksi in H38), and no measured seawater corrosion rate was found in the sources read |
| Aluminium-magnesium alloys (5XXX series) | Welded, corrosion-resistant sheet and plate at moderate strength (5083 is sold for ship building and pressure vessels) | Strength per alloy is modest next to heat-treated 6061, and 5083 is not recommended above 65 °C because of grain-boundary attack |
| Aluminium-lithium alloy 2195 | Welded cryogenic tanks where friction stir welding keeps most of the strength (NASA reports, 1998 to 2008) | Fusion welding, which hot-cracks and needs repairs, and corrosion resistance, which the supplier calls poor |
| Aluminium | Light, cheap electrical and thermal conduction, and a positive-electrode foil that stays passive in common lithium-ion electrolytes | Strength: annealed pure aluminium has a typical yield strength near 22 to 29 MPa, so it is not a structural metal on its own |
| Aluminium alloy 1050 | Formed sheet, chemical plant and heat-transfer parts that need very good corrosion resistance and easy forming more than strength (Smiths and Righton list these uses) | Low strength in the soft tempers (Smiths gives 100 to 135 N/mm2 typical tensile for 1050A H14, and 1200 O is 70 to 105 N/mm2); no measured corrosion test data were read |
| Aluminium alloy 2011 | Small, complex, high-precision machined parts made on automatic lathes, such as screws, bolts, gears, fasteners and fittings (suppliers rate machinability very good to excellent) | Weldability (rated poor to extremely poor by the sources) and corrosion resistance (rated low to moderate, and anodising or another surface treatment is advised) |
| Aluminium alloy 2014 | High-strength structural parts for aerospace and defence, where a 460 MPa minimum tensile strength in T651 plate is needed and the part is clad or painted against corrosion | Corrosion resistance (poor in water and salt, with pitting and galvanic attack in sea water), and welding, which is difficult and prone to cracking |
| Aluminium alloy 2017 | High-strength machined parts and rivets in aircraft-type structures, in the T4 temper (supplier rates machinability excellent, strength very good) | Weldability (only resistance welding is suitable, per the AircraftMaterials datasheet) and corrosion resistance (rated moderate by the supplier, with no test data found for this grade) |
| Aluminium alloy 2017A | Machined structural parts and solid rivets in the T4 temper (supplier rates machinability Excellent, yield strength 276 MPa) | Welding (resistance welding only, per the Smith and AircraftMaterials datasheets) and corrosion resistance (rated moderate by one supplier and good by another, with no test data for this grade) |
| Aluminium alloy 2219 | Launch-vehicle and cryogenic tankage where weldability and fracture toughness matter (Smith datasheet: readily weldable, good fracture toughness; Alloys International: launch vehicle and cryogenic tanks) | Ductility in thick plate, where 5-inch T87 plate showed below 1 % in the short-transverse direction (NASA 2021), and general corrosion resistance, which Wikipedia describes as lower than other aluminium alloys |
| Aluminium alloy 3003 | Sheet and formed parts that need moderate strength, good workability and weldability, and resistance to atmospheric corrosion, such as storage tanks, chemical equipment and heat exchangers, with the temper named | Strength depends on temper, from 14 to 19 ksi tensile in O to 27 ksi minimum in H18, and no seawater rating or measured corrosion rate for 3003 was found in the sources read |
| Aluminium alloy 5083 | Welded marine structures and pressure vessels kept at or below 65 °C, where seawater resistance and strength matter (supplier datasheets) | Service above 65 °C, where the suppliers advise against use. It is a non-heat-treatable alloy (Dinco sheet). No space-environment data were found. |
| Aluminium alloy 5251 (AlMg2) | Welded marine and sheet-metal structures where seawater corrosion resistance and weldability matter more than peak strength, at 2.69 g/cm3 | Strength compared with heat-treatable alloys: H22 minimum proof stress is 120 MPa, and a good weld reaches only about 160 MPa (Smith) |
| Aluminium alloy 5754 (AlMg3) | Welded structures and marine or chemical service where seawater corrosion resistance matters, at a density of about 2.67 g/cm3 | Strength against heat-treatable aluminium alloys, since strength comes from the temper, and the risk of sensitisation in magnesium-rich grades held warm for long periods (no temperature threshold for this grade was verified) |
| Aluminium alloy 6013 | Light structural aluminium for aerospace and general structural use: 2.71 g/cm3 density, and 350 MPa yield in the T651 temper (supplier page) | Dust and chips ignite readily during machining (Hydro SDS). No fatigue, fracture-toughness or T6 temper data was opened, and the sources disagree on thermal expansion |
| Aluminium alloy 6063 | Architectural extrusions such as window and door frames, rails and trim that need a smooth anodised finish (Alloys International; AZoM). | Strength: Alloys International says 6061 is the higher-strength choice for structural parts, and no space-environment, cryogenic or galvanic data were found for 6063. |
| Aluminium alloy 6082 | Structural parts that must be strong but light: T6 and T651 plate with minimum proof stress 255 MPa and density 2.70 g/cm3 | Strength in the weld zone, which the supplier says is lowered by welding, and pitting or intergranular attack in chloride solution (lab immersion test at 50 °C) |
| Aluminium alloy 7050 (AA7050) | Thick, high-strength aerospace structure in the over-aged T74 or T7451 conditions, where high yield strength and good exfoliation resistance are needed | Weld zones: friction-stir welds of 7050-T7451 showed less cracking resistance than 7075-T651 welds in constant extension rate tests (2003 study) |
| Aluminium alloy 8011 (AA8011) | Thin, light foil and fin stock: 2.71 g/cm3 density with 210 to 220 W/(m·K) thermal conductivity in H19 foil at 20 °C | Yield strength and corrosion data are missing from this profile, and no spacecraft use was found in any source read |
Where each is used
| Material | Use |
|---|---|
| Commercially pure titanium, Grade 2 (UNS R50400) | Seawater-cooled heat exchanger and condenser tubing |
| Commercially pure titanium, Grade 2 (UNS R50400) | Desalination pipe and reverse-osmosis pressure vessels |
| Commercially pure titanium, Grade 2 (UNS R50400) | Aerospace hydraulic tubing (AMS 4943 annealed; AMS 4944 and 4945 cold worked and stress relieved) |
| Ti-6Al-4V | Aerospace forging and bar (example of an AMS 4928 bar forging) |
| Ti-6Al-4V | Aircraft and spacecraft structural parts made to AMS 4928 and AMS 4911 |
| Aluminium alloy 6061 | Launch vehicle and spacecraft structures (aluminium alloys, 6061 named as a structural alloy) |
| Aluminium alloy 6061 | Simulated propellant tanks of 6061-T3 sheet (ground impact tests, not flown) |
| Aluminium alloy 6061 | Fittings, couplings, hinge pins, valves and valve parts, and hydraulic and brake pistons |
| Aluminium alloy 7075-T6 | Aircraft structures and airframe parts |
| Aluminium alloy 7075-T6 | High-pressure hydraulic units |