Titanium vs Aluminum
Titanium is about 1.6 times as dense as aluminum, so it is not the lighter metal. What it offers is strength: annealed Ti-6Al-4V, the grade in most titanium parts, yields at about 880 MPa (128 ksi), more than three times 6061-T6 and well above 7075-T6, so per pound it is roughly twice as strong as 6061. It also shrugs off seawater and chlorides, and keeps useful strength to about 400 °C (750 °F), where aluminum is finished above about 150 °C.
What titanium does not offer is stiffness per pound: its modulus is about 1.65 times that of aluminum, almost exactly its density ratio, so a stiffness-limited part weighs about the same in either. Titanium also costs several times more per pound and machines several times slower. The representative grades here, Ti-6Al-4V and 6061-T6, split cleanly: aluminum by default, titanium where strength per pound, corrosion, heat or biocompatibility justify the price.
| Property | Titanium | Aluminum |
|---|---|---|
| Representative grade | Ti-6Al-4V (Grade 5), annealed | 6061-T6 |
| Density | 4.43 g/cm³ | 2.70 g/cm³ |
| Tensile | ~950 MPa (138 ksi); 895 MPa (130 ksi) min | 310 MPa (45 ksi) |
| Yield | ~880 MPa (128 ksi); 828 MPa (120 ksi) min | 276 MPa (40 ksi) |
| Yield / density | ~200 kN·m/kg | ~100 kN·m/kg (7075-T6 ~180) |
| Modulus | 114 GPa (16.5 Msi) | 69 GPa (10 Msi) |
| Modulus / density | About the same | About the same |
| Hardness | ~36 HRC | ~95 HB |
| Thermal conductivity | ~7 W/m·K | ~167 W/m·K |
| Max useful temperature | ~400 °C (750 °F) | ~150 °C (300 °F) |
| Typical uses | Aerospace fittings and fasteners, implants, marine and chemical hardware, racing parts | Frames, enclosures, brackets, heat sinks, fixtures, general machined parts |
Typical values for the stated conditions. Confirm against the mill certificate and your spec.
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- Finishing & Heat Treating companies that work with aluminum · 546
- All U.S. manufacturers working with aluminum · 2,300
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Decision matrix
A check marks the side with the edge on that dimension.
| Dimension | Titanium | Aluminum |
|---|---|---|
| Machining | Fair to poor; slow speeds, heat and tool wear, 4-8x aluminum cycle time | ✓ Excellent; fast, cheap, forgiving |
| Welding | Good, but the hot weld must be fully shielded in argon; fewer qualified shops | Good; TIG and MIG everywhere, heat-affected zone loses T6 strength |
| Forming | Poor cold in Ti-6Al-4V; hot or superplastic forming, or CP grades for sheet | ✓ Excellent in O and T4; fair in T6 |
| Strength | ✓ ~880 MPa yield, about twice 6061 per pound | 276 MPa yield; 7075 closes much of the gap |
| Corrosion resistance | ✓ Excellent; immune to seawater and most chlorides | Good; anodize for marine, pits in chlorides |
| Finishing | Color and anti-galling anodize, blasting, passivation | ✓ Anodize, hardcoat, chem film, powder coat, any color |
| Material cost | Roughly 8-15x 304 per pound; a machined part often 5-10x the 6061 part | ✓ Baseline; low material and machining cost |
| Availability | Bar, plate and sheet from specialty distributors, often with aerospace or medical certs | ✓ Every form in every service center, plus extrusions |
Choose Titanium when
- Strength per pound beyond what 7075 offers: highly loaded aerospace fittings, fasteners and landing-gear parts
- Seawater, chloride, bleach or body-fluid exposure without a coating: marine, chemical and implant parts (ASTM F136 for implants)
- Service between about 150 and 400 °C, where aluminum loses its temper
- Parts bolted into carbon-fiber structure, where aluminum corrodes galvanically and expands too much
Choose Aluminum when
- Cost and lead time matter: aluminum parts quote cheaper and ship faster
- Stiffness-limited parts, where titanium saves no weight because its stiffness per pound is the same
- Heat sinks, cold plates and anything that must move heat
- Heavily machined parts, sheet-metal enclosures and custom extrusions
Frequently asked questions
- Is titanium stronger than aluminum?
- Yes. Annealed Ti-6Al-4V yields at about 880 MPa (128 ksi), more than three times 6061-T6 and about 75% more than 7075-T6. Because titanium is also 1.6 times as dense, the advantage per pound is smaller: roughly twice 6061 and about 10% over 7075.
- Is titanium lighter than aluminum?
- No. Titanium is about 4.4 g/cm³ and aluminum about 2.7 g/cm³, so a titanium part of the same shape is about 65% heavier. Titanium saves weight only when its higher strength lets the part be made smaller.
- Why is titanium so much more expensive than aluminum?
- The metal is costly to extract and melt, which puts Ti-6Al-4V at roughly 8-15 times the price of 304 stainless per pound, and it machines several times slower than aluminum because it runs hot and wears tools. A machined titanium part often costs 5-10 times the same part in 6061.
- Can you use titanium fasteners in aluminum?
- Yes, and aircraft do, but the aluminum is the anodic side of the couple and will corrode if the joint stays wet. Install titanium fasteners with sealant or a coating, and anodize or prime the aluminum. In dry service the couple is not a problem.
