Titanium Grade 9 (UNS R56320), commonly referred to in the aerospace and metallurgical industries as Ti-3Al-2.5V or "Half-6-4", is a highly specialized near-alpha titanium alloy. It was intentionally developed to bridge the critical engineering gap between the extreme formability of Commercially Pure (CP) titanium grades and the massive, but rigid, tensile strength of Grade 5 (Ti-6Al-4V). By alloying the titanium matrix with exactly 3% Aluminum (an alpha phase stabilizer) and 2.5% Vanadium (a beta phase stabilizer), the metal achieves a remarkable synergy of properties.
Grade 9 boasts a yield strength that is 20% to 50% higher than Commercially Pure Grade 4, yet it retains phenomenal cold-forming and welding capabilities that Grade 5 lacks. Because it can be aggressively cold-worked (rolled, headed, or drawn) without severe micro-fracturing, UNS R56320 fasteners are the premier lightweight hardware choice for high-pressure aerospace hydraulic lines, elite professional sports equipment, and deep-water marine rigging where both high dynamic strength and complex manufacturing geometries are required.
| Material Classification | Near-Alpha Titanium Alloy (Ti-3Al-2.5V) |
|---|---|
| UNS Designation | R56320 |
| Microstructure | Alpha-Beta Matrix (Predominantly Alpha) |
| Magnetic State | Completely Non-Magnetic |
| Density | 4.48 g/cm³ (0.162 lb/in³) — Exceptionally Lightweight |
| Size Range | Metric: M3 to M36 | Imperial: #4 to 1-1/2" |
| Primary Attribute | Perfect Balance of High Strength, Cold Formability, and Weldability |
Contains detailed cold-heading upset ratios for aerospace rivets, cyclic fatigue (S-N) curves for dynamic loading, and specialized TIG welding shielding parameters.
⬇ DOWNLOAD DATASHEETIn both aerospace and high-performance racing, structural failure due to interstitial gas embrittlement is catastrophic. Ananka provides absolute traceability, ensuring that the Aluminum-Vanadium stoichiometry and strict Oxygen limits of every fastener are authenticated via Vacuum Arc Remelting (VAR) mill certificates.
The brilliance of Grade 9 lies in its "Half-6-4" composition. By utilizing roughly half the Aluminum and Vanadium found in Grade 5, the alloy gains significant tensile strength over unalloyed titanium while keeping the crystal lattice pliable enough for aggressive cold forming and seamless welding without cracking.
| Titanium (Ti) | Aluminum (Al) | Vanadium (V) | Iron (Fe) | Oxygen (O) | Carbon (C) |
|---|---|---|---|---|---|
| Balance (~94.5) | 2.50 – 3.50 | 2.00 – 3.00 | 0.25 Max | 0.15 Max | 0.05 Max |
| Mechanical Property | Typical Limits (Annealed Temper) |
|---|---|
| Tensile Strength | 90,000 - 105,000 psi (620 - 725 MPa) |
| Yield Strength (0.2% Offset) | 75,000 - 90,000 psi (515 - 620 MPa) |
| Elongation (in 2 inches) | 15% Minimum |
| Hardness (Brinell) | ~ 200 HB (approx. 94 HRB) |
| Standard / System | Designation |
|---|---|
| ASTM Specifications | ASTM B348 (Rod/Bar), ASTM F467 / F468 (Fasteners) |
| Common Trade Names | Ti-3Al-2.5V, Grade 9 Titanium, Half-6-4 |
| Aerospace Standard | AMS 4943, AMS 4944 |
| European Equivalent | EN 3.7195 |
| Mating Bolts/Studs/Rivets | Internal Threads (Nuts) | Washers / Gaskets |
|---|---|---|
| Grade 9 Ti-3Al-2.5V Hex Bolts | Grade 9 Ti-3Al-2.5V Hex Nuts | Grade 9 Flat Washers / PTFE |
Grade 9 titanium has an excellent strength profile, falling just shy of Grade 5, meaning it can withstand substantial torque loads. However, like all titanium alloys, its protective surface oxide makes it highly susceptible to severe thread galling (seizing) when tightened under friction. Heavy application of premium aerospace-grade anti-seize pastes (Molybdenum Disulfide or PTFE-based) is absolutely mandatory prior to applying torque.
| Nominal Diameter | Threads Per Inch (UNC) | Max Target Torque (in-lbs) — Lubricated | Max Target Torque (ft-lbs) — Lubricated |
|---|---|---|---|
| 1/4" | 20 | 70 - 80 | ~ 6.0 |
| 5/16" | 18 | 150 - 170 | ~ 13.5 |
| 3/8" | 16 | 270 - 300 | ~ 24.0 |
| 1/2" | 13 | 580 - 640 | ~ 50.0 |
While Grade 5 is significantly stronger, it is rigid and brittle at room temperature, making it notoriously difficult to cold-form or draw into complex shapes (like seamless tubing or cold-headed rivets). Grade 9 was specifically designed to be cold-workable. If an engineering design requires a fastener with higher strength than pure titanium but still needs to be heavily shaped, swaged, or welded easily without cracking, Grade 9 is the optimal choice.
Yes, it has exceptional weldability compared to Grade 5. However, the standard titanium welding rules strictly apply: the metal must be completely shielded from atmospheric oxygen and nitrogen during the welding and cooling process. TIG welding with an inert argon trailing shield and back-purge is mandatory to prevent the weld pool from absorbing gases and shattering.
No. Titanium Grade 9 shares the same legendary corrosion resistance as Commercially Pure titanium grades. It is completely immune to chloride-induced stress corrosion cracking, marine biofouling, and localized pitting in ocean water, making it a lifetime hardware solution for submerged maritime applications.
