Titanium Alloys
Titanium is impressive on paper — strong, light, corrosion-proof. It's also expensive, slow to machine, and often specified when aluminum or stainless would do the job at half the cost. This page helps you decide when titanium is genuinely needed and how to handle it.
Is Titanium Worth It?
| Your Situation | Use Titanium? | Better Alternative |
|---|
| Aerospace / airframe structural | Yes | — |
| Medical implants (biocompatibility) | Yes | — |
| Marine (saltwater, no heat) | Maybe | 316L stainless is cheaper for non-load parts |
| Chemical processing (corrosive) | Maybe | Hastelloy or super duplex may be better |
| High strength-to-weight (non-aero) | Maybe | 7075-T6 aluminum is cheaper if non-corrosive |
| Just need lightweight + strong | No | 7075 aluminum (same strength, 40% the cost) |
| Just need corrosion resistance | No | 316 stainless (5–10x cheaper) |
| Prototype / low volume | No | Prototype in aluminum or steel first |
Cost reality check
Titanium raw material costs 5–10x more than aluminum, and 3–5x more than stainless. Machining costs 2–3x more than steel due to low cutting speeds and rapid tool wear. Only specify titanium when you have a genuine requirement for its unique combination of strength, weight, and corrosion resistance.
Grade 2 vs Ti-6Al-4V
| Property | Grade 2 (CP) | Ti-6Al-4V (Grade 5) |
|---|
| Type | Commercially pure | Alpha-beta alloy |
| Tensile (MPa) | 275–410 | 895–930 |
| Yield (MPa) | 170–275 | 825–860 |
| Density (g/cm³) | 4.51 | 4.43 |
| Hardness | 200–275 HB | 33–36 HRC |
| Weldable | Yes | Difficult (requires protection) |
| Heat treatable | No | Yes (aging increases strength) |
| Machinability | Better | Hard on tools |
| Relative cost | 1.0x | 1.3–1.5x |
| Use for | Chemical, marine, biomedical | Aerospace, high-strength |
Simple rule
Need corrosion resistance (not high strength)? Use Grade 2. Need high strength + light weight? Use Ti-6Al-4V. That covers 95% of titanium applications.
Machining Titanium — The Hard Truth
| Rule | Detail |
|---|
| Low cutting speed | 30–60 m/min for Grade 2, 20–45 m/min for Ti-6Al-4V. Going faster just burns the tool without cutting faster. |
| Flood coolant | Mandatory. Titanium has poor thermal conductivity — heat stays at the cutting edge. Without flood coolant, tool life drops to minutes. |
| Sharp tools, replaced frequently | Titanium work-hardens. A dull tool creates a hardened surface layer that kills the next tool too. |
| Low rake angle | Use positive rake tools but with a sharper edge. TiAlN or diamond-coated end mills last 3–5x longer. |
| Thin chips | Keep radial depth of cut small. Thick chips in titanium generate too much heat. Multiple shallow passes. |
| Fire risk | Titanium chips can ignite. Never use cutting oil — use water-based coolant. Clean chips regularly. |
Titanium fire
Fine titanium chips can ignite, especially in dry machining. Titanium fires burn at 3000°C+ and cannot be extinguished with water (they burn hotter). This is rare but real. Use water-based flood coolant and keep the machine clean of chips.
Surface Treatment
| Treatment | Purpose | Notes |
|---|
| Anodize (Type II) | Color, wear resistance | Produces blue/purple/gold colors. Popular for medical and aerospace. |
| Grit blasting | Surface preparation | Creates matte finish. Required before many coating processes. |
| Polishing | Mirror finish | Possible but labor-intensive. Titanium polishes well. |
| PVD coating | Wear resistance | TiN, CrN on titanium for reduced friction. Used in medical implants. |
Common Mistakes
| Mistake | What happens | Correct approach |
|---|
| Specifying titanium when aluminum suffices | Paying 5–10x material cost for no benefit | Do the calculation: strength/weight/corrosion requirement. Most parts don't need titanium. |
| High cutting speed | Tool burns out in minutes, poor surface finish | Keep below 60 m/min for Grade 2, 45 m/min for Ti-6Al-4V |
| Using cutting oil | Fire risk with titanium chips | Water-based coolant only |
| Not changing tools frequently enough | Work-hardened surface kills subsequent tools | Replace at first sign of wear |
| Grade 2 for high-strength parts | Yield only 275 MPa — weaker than 6061-T6 | High strength requires Ti-6Al-4V |