Titanium grades — the cross-reference
What Grade 5, TA2, TC4 and 3.7165 actually are, and how the designations map across ASTM, GB (Chinese), ISO and DIN standards.
One metal, four naming systems
Buyers meet titanium under different names depending on where the drawing was made: ASTM (US), GB (China), ISO and DIN/EN (Europe). The grades correspond closely — but composition limits, product forms and certificate requirements differ by standard, so always confirm against the drawing callout. Use this table to translate any quote, mill certificate or drawing callout.
| ASTM | GB (China) | ISO | DIN/EN | Nominal composition | Character |
|---|---|---|---|---|---|
| Grade 1 | TA1 | Ti CP-1 | 3.7025 | Ti ≥ 99.5% | Softest, most ductile CP grade |
| Grade 2 | TA2 | Ti CP-2 | 3.7035 | Ti ≥ 99.2% | The industrial workhorse |
| Grade 3 | TA3 | Ti CP-3 | 3.7055 | Ti ≥ 99.1% | Higher-strength CP |
| Grade 5 | TC4 | Ti-6Al-4V | 3.7165 | 6% Al · 4% V | The aerospace alloy — strong, weldable |
| Grade 9 | TA18 | Ti-3Al-2.5V | 3.7195 | 3% Al · 2.5% V | The tubing alloy — formable, strong |
| Grade 23 | TC4 ELI | Ti-6Al-4V ELI | 3.7165 ELI | 6% Al · 4% V (low O₂) | Medical-grade toughness |
Key mechanical properties
Grade 5 offers the best strength-to-weight of the common grades at the cost of reduced formability. Grade 2 trades roughly half the strength for outstanding ductility, weldability and corrosion resistance. Grade 9 sits between them and was designed for hydraulic and bicycle tubing.
Which grade for which job
- Corrosion-dominated parts (chemical, marine, immersion): Grade 2 — or Grade 7 if reducing-acid service demands the Pd upgrade.
- Strength-dominated parts (structural, bolts, bike components, robotics): Grade 5.
- Tubing, frames, pressure lines drawn and welded: Grade 9.
- Anything that touches the body long-term or sees cryogenic temperatures: Grade 23 (ELI).
Updated 2026-09
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