Titanium vs Aluminum for Machined Parts
Both are "lightweight metals," but they solve different problems. Density, strength, strength-to-weight, machinability, corrosion, and cost — compared with real grade data, not marketing adjectives.
IsoCNC Engineering Team
CNC Machining & DFM Engineers · Updated · 10 min read
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Two Lightweight Metals, Two Different Jobs
Aluminum and titanium get compared constantly because both promise light weight. But the comparison only makes sense with numbers. Aluminum is the productivity metal: light (2.70–2.81 g/cm³), easy to machine, affordable, available everywhere. Titanium is the performance metal: roughly 60% denser than aluminum but three times stronger, corrosion-proof in environments that eat aluminum, and stable at temperatures that soften aluminum alloys. The real engineering question is never "which is better" — it is whether your part's loads, environment, and budget actually need what titanium charges for.
Titanium vs Aluminum at a Glance
The four grades that cover most machined-part drawings — strength-to-weight calculated as tensile strength ÷ density:
| Property | Ti-6Al-4V (Gr 5) | Titanium Gr 2 (CP) | 7075-T6 | 6061-T6 |
|---|---|---|---|---|
| Density | 4.43 g/cm³ | 4.55 g/cm³ | 2.81 g/cm³ | 2.70 g/cm³ |
| Yield strength | 880 MPa | 275 MPa | 503 MPa | 276 MPa |
| Tensile strength | 950 MPa | 345 MPa | 572 MPa | 310 MPa |
| Strength-to-weight | ~214 | ~76 | ~204 | ~115 |
| Thermal conductivity | 6.7 W/m·K | 16.4 W/m·K | 130 W/m·K | 167 W/m·K |
| Machinability | Difficult | Moderate | Good | Excellent |
| Typical uses | Aerospace structures, implants | Marine, chemical, medical | Aerospace, high-stress parts | General precision parts |
Two numbers in this table surprise most buyers: 7075-T6 aluminum nearly matches Ti-6Al-4V on strength-to-weight (204 vs 214), and commercially pure Grade 2 titanium is actually weaker than 7075 in absolute terms. Titanium's case rests on more than the strength ratio — keep reading. Those tensile numbers come straight off each alloy’s stress-strain curve, which also shows how much warning a material gives before it fails.
Strength and Weight: What the Ratio Actually Buys
Titanium's 950 MPa tensile strength means a Ti-6Al-4V bracket can be designed with much thinner sections than a 6061 bracket carrying the same load — thin enough that the finished titanium part can weigh less than the aluminum one despite the higher density. That is the entire aerospace logic: buy strength, spend it on section reduction.
But notice where the crossover sits. If your design can live with 7075-T6's 572 MPa and slightly thicker walls, aluminum delivers nearly the same specific strength at a fraction of the part cost. Titanium only pays off when you need its extras: strength at elevated temperature (aluminum alloys fade fast above roughly 150–200°C while titanium keeps working), extreme corrosion resistance, or biocompatibility. If none of those are in play, 7075 is usually the economically correct answer — see our 6061 vs 7075 comparison for the aluminum-side choice.
Machinability: Where Titanium Bills You
This is the section that shows up on your quote. Aluminum is a joy to cut: 6061-T6 conducts heat at 167 W/m·K, so cutting heat leaves with the chip, tools stay cool, and carbide runs at 300–600 m/min. Ti-6Al-4V conducts heat at 6.7 W/m·K — 4% of 6061's value. The heat has nowhere to go except into the tool edge. Titanium also work-hardens if the tool rubs instead of cuts, and it chemically reacts with tool coatings at cutting temperature.
The consequences are mechanical: cutting speeds drop to roughly 40–80 m/min, setups need maximum rigidity, coolant arrives at high pressure, and tools wear fast. Cycle times stretch by multiples, not percentages. Grade 2 titanium is noticeably kinder (16.4 W/m·K, lower strength), but still far slower than any aluminum. When we quote the same geometry in titanium versus aluminum, the titanium part routinely costs several times more — and that is before the raw material price difference, which is also substantial. Specify titanium because the part needs it, never because it sounds premium.
Corrosion, Temperature, and Biocompatibility
Corrosion: titanium's self-healing oxide film is one of the most stable in engineering — seawater, chlorides, and most chemicals leave it untouched. Aluminum resists atmospheric corrosion well but is vulnerable to pitting in chloride environments and galvanic attack when coupled to more noble metals; anodizing or coating is the usual mitigation. For marine or chemical service, titanium (often Grade 2) is the conservative choice.
Temperature: aluminum alloys lose strength quickly as service temperature climbs — common grades are effectively done as structural materials somewhere around 150–200°C. Titanium alloys retain useful strength well beyond that range, which is why they appear around engines, exhausts, and hot airframe zones.
Biocompatibility: titanium is the default implant metal — bone and tissue tolerate it, and both Grade 2 and Grade 5 are medical staples. Aluminum is not used inside the body. If the part touches a patient, the decision is already made.
Pushed past titanium’s temperature ceiling? The superalloy alternative is covered in our Inconel vs titanium comparison.
Cost: Material Plus Machine Time
Titanium raw material costs several times more than aluminum per kilogram — and the part costs more than the material ratio suggests, because the machinability gap multiplies through every operation. A part that runs unattended in 6061 becomes a supervised, slow, tool-hungry job in Ti-6Al-4V. As a budgeting rule: if the aluminum version of your part costs X, expect the titanium version to land at a multiple of X, not X plus a material surcharge. The corollary is worth stating too: if a titanium quote looks only slightly above aluminum, someone has not thought about tool wear.
Know Your Grades
Grade 2 (commercially pure): 275 MPa yield, 345 MPa tensile, 4.55 g/cm³. The corrosion specialist — marine hardware, chemical processing, medical. Softer, more formable, and the easiest titanium to machine.
Grade 5 (Ti-6Al-4V): 880 MPa yield, 950 MPa tensile, 4.43 g/cm³. Over half of all titanium usage. Aerospace structures, loaded implants, performance parts. Hard to machine; price accordingly.
6061-T6: 276 MPa yield, 2.70 g/cm³. The default aluminum — excellent machinability, weldable, anodizes beautifully. General precision parts, enclosures, fixtures. If the print just says 6061, confirm the temper before quoting — 6061-T6 vs T651 differ mainly in stress relief, which decides how much a thin-walled part moves after machining.
7075-T6: 503 MPa yield, 2.81 g/cm³. The aerospace aluminum — near-titanium specific strength, still highly machinable. High-stress brackets, structural parts, anything where 6061 is not quite enough.
How to Choose
Choose 6061-T6 aluminum for general precision parts, enclosures, prototypes, and production runs where loads are moderate. Fastest, cheapest, finishes beautifully.
Choose 7075-T6 aluminum when you need near-titanium specific strength without titanium's cost — high-stress brackets, aerospace fittings, performance automotive — we break down the vehicle-specific versions in our automotive CNC parts guide.
Choose Grade 2 titanium for marine, chemical, and medical hardware where corrosion resistance is the driving requirement and loads are moderate.
Choose Grade 5 titanium when strength-to-weight is the top priority and the budget supports it: aerospace structures, implants under load, racing components, parts that see heat.
Grade-by-grade details on our material pages: titanium CNC machining and aluminum CNC machining. Choosing between aluminum alloys? See 6061 vs 5052 and 6061 vs 6063.
Related: Need even lighter than aluminum? Our magnesium machining guide covers AZ31B, cutting speeds, and the chip fire-safety rules. And when weight is not the driver at all, the copper alloys are their own branch of the decision — brass vs bronze vs copper covers that comparison.
FAQ
Is titanium stronger than aluminum?
Yes, dramatically. Ti-6Al-4V (Grade 5) has a tensile strength around 950 MPa versus 310 MPa for 6061-T6 and 572 MPa for 7075-T6, the strongest common aluminum alloy. Even commercially pure Grade 2 titanium (345 MPa) edges out 6061-T6. If absolute strength in a compact envelope is the requirement, titanium wins.
Is titanium lighter than aluminum?
No — this is the most common misconception. Titanium (4.43–4.55 g/cm³) is about 60% denser than aluminum (2.70–2.81 g/cm³). Titanium’s advantage is strength-to-weight: it is so much stronger that a titanium part can be designed thinner and end up lighter than an aluminum part carrying the same load. Same geometry, same volume — the aluminum part is always lighter.
Why is titanium so expensive to machine?
Heat. Ti-6Al-4V conducts heat at only 6.7 W/m·K — about 4% of 6061 aluminum’s 167 W/m·K — so cutting heat concentrates at the tool edge instead of leaving with the chip. Add work hardening and chemical reactivity with the tool, and the result is slow cutting speeds (roughly 40–80 m/min versus 300–600 for aluminum), high-pressure coolant, rigid setups, and fast tool wear. A titanium part routinely costs several times more to machine than the same geometry in aluminum — before you even count the raw material price difference.
Can titanium be anodized like aluminum?
Yes, but it is a different process with a different purpose. Aluminum anodizing (Type II / Type III) builds a protective, wear-resistant oxide layer that can be dyed. Titanium anodizing grows a thin interference oxide film that creates color through light refraction — used for cosmetic color coding and medical implant identification, not for wear protection. For corrosion resistance, titanium barely needs help: its natural oxide film is already exceptionally stable.
Grade 2 or Grade 5 titanium — which do I need?
Grade 2 is commercially pure titanium: softer (275 MPa yield), more formable, easier to machine, excellent corrosion resistance — used for marine, chemical-processing, and medical hardware. Grade 5 (Ti-6Al-4V) is the workhorse alloy: 880 MPa yield, far harder to machine, used for aerospace structures, implants under load, and performance parts. If your drawing just says “titanium,” ask which grade — the machining quote will differ significantly.
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Sources
Standards and references behind the numbers on this page.
- MatWeb, Titanium Ti-6Al-4V (Grade 5) datasheet — density, tensile and yield strength for the titanium column
- MatWeb, Aluminum 6061-T6 datasheet — the default aluminum properties in the comparison table
- MatWeb, Aluminum 7075-T6 datasheet — the high-strength aluminum figures
Titanium and Aluminum, Machined In-House
IsoCNC machines both metals daily — from 6061 prototypes to Ti-6Al-4V production parts with full inspection reports. Send the drawing; an engineer reviews every RFQ, typically within 1–2 business days.