Titanium Grade 11 (UNS R52250) is a highly specialized modification of Commercially Pure (CP) Titanium Grade 1. While it retains the extreme ductility, optimum cold-formability, and low strength of Grade 1, it is precisely alloyed with a small but critical addition of 0.12% to 0.25% Palladium (Pd). This precious metal addition triggers a remarkable metallurgical phenomenon, drastically shifting the alloy's corrosion potential and granting it an extraordinary ability to passivate in highly aggressive reducing environments.
Standard unalloyed titanium relies on oxygen to maintain its protective oxide layer and can suffer severe crevice corrosion in hot, oxygen-starved chloride solutions or reducing acids (like Hydrochloric or Sulfuric acid). The Palladium in Grade 11 acts as a cathodic depolarizer, allowing the metal to instantly repair its oxide film even in boiling, low-pH brines. This makes UNS R52250 fasteners the ultimate failsafe for critical desalination infrastructure, chlorine dioxide bleaching plants, and deep-water subsea equipment where crevice corrosion is a guaranteed threat.
| Material Classification | Palladium-Alloyed Commercially Pure Titanium |
|---|---|
| UNS Designation | R52250 |
| Microstructure | Single-Phase Alpha Matrix |
| Magnetic State | Completely Non-Magnetic |
| Density | 4.51 g/cm³ (0.163 lb/in³) — Exceptionally Lightweight |
| Size Range | Metric: M2 to M36 | Imperial: #2 to 1-1/2" |
| Primary Attribute | Ultimate Immunity to Crevice Corrosion in Hot Chlorides |
Contains detailed isocorrosion charts for boiling Hydrochloric Acid (HCl), specific cathodic passivation limits, and anti-galling lubrication guidelines for Palladium-alloyed hardware.
⬇ DOWNLOAD DATASHEETBecause Grade 11 relies on a precious metal addition to survive extreme environments, precise verification of the Palladium content is legally and operationally mandatory for chemical plant safety. Ananka provides absolute traceability, ensuring every fastener is mapped back to its primary Vacuum Arc Remelting (VAR) ingot.
Metallurgically, Grade 11 is identical to the highly ductile Grade 1, with one crucial exception: the Palladium (Pd). This minute addition does not noticeably change the metal's strength or formability, but it profoundly alters its surface electrochemistry, forcing the titanium into a passive (protected) state even when oxygen is absent.
| Titanium (Ti) | Palladium (Pd) | Oxygen (O) | Iron (Fe) | Carbon (C) | Hydrogen (H) |
|---|---|---|---|---|---|
| Balance (~99.3) | 0.12 – 0.25 | 0.18 Max | 0.20 Max | 0.08 Max | 0.015 Max |
| Mechanical Property | Typical Limits (Annealed Temper) |
|---|---|
| Tensile Strength | 35,000 psi (240 MPa) Minimum |
| Yield Strength (0.2% Offset) | 25,000 - 45,000 psi (170 - 310 MPa) |
| Elongation (in 2 inches) | 24% Minimum |
| Hardness (Brinell) | ~ 120 HB (approx. 70 HRB) |
| Standard / System | Designation |
|---|---|
| ASTM Specifications | ASTM B348 (Rod/Bar), ASTM F467 / F468 (Fasteners) |
| Common Trade Names | Ti-0.2Pd, Grade 11 Titanium, CP Ti-Pd Alloy |
| European Equivalent | Titanium 3.7025 + Pd (Approximate) |
| Mating Bolts/Studs/Rivets | Internal Threads (Nuts) | Washers / Gaskets |
|---|---|---|
| Grade 11 CP Titanium Bolts & Studs | Grade 11 CP Titanium Hex Nuts | Grade 11 Flat Washers / PTFE |
CRITICAL WARNING: Grade 11 Titanium is mechanically identical to Grade 1—meaning it is extremely soft, ductile, and incredibly prone to thread galling (seizing). Over-torquing will rapidly strip the threads or stretch the bolt beyond its yield point. Heavy application of premium dialectric anti-seize pastes or PTFE-based lubricants is absolutely mandatory prior to installation.
| Nominal Diameter | Threads Per Inch (UNC) | Max Target Torque (in-lbs) — Lubricated | Max Target Torque (ft-lbs) — Lubricated |
|---|---|---|---|
| 1/4" | 20 | 45 - 55 | ~ 4.0 |
| 5/16" | 18 | 90 - 110 | ~ 8.0 |
| 3/8" | 16 | 160 - 180 | ~ 14.0 |
| 1/2" | 13 | 350 - 390 | ~ 31.0 |
Both Grade 7 and Grade 11 are Palladium-alloyed to provide extreme resistance to crevice corrosion. The difference lies in their base metal. Grade 7 is based on Titanium Grade 2 (which is stronger but less ductile). Grade 11 is based on Titanium Grade 1 (which is softer, with lower oxygen content). Grade 11 is selected when severe deep-drawing, complex cold-forming, or maximum ductility is required alongside the chemical resistance of Palladium.
Titanium naturally protects itself with an oxide film, but in "reducing" acids (where there is no oxygen available to repair the film), the titanium begins to dissolve. Palladium is a noble, highly cathodic metal. When alloyed into the titanium, it acts as a microscopic "depolarizer." It lowers the energy required for the titanium to form its oxide layer, forcing the metal to passivate (protect itself) even in environments that would normally destroy it.
Yes. Because it is essentially unalloyed titanium (the Palladium content is too small to affect the physical welding properties), Grade 11 welds beautifully. However, like all titanium grades, welding must be done under strict inert gas shielding (100% Argon or Helium) to prevent the molten metal from absorbing oxygen and shattering upon cooling.
