Titanium Grade 12 (UNS R53400) is a highly specialized, low-alloy titanium grade engineered specifically for severe industrial environments. Known colloquially as Ti-0.3Mo-0.8Ni, this alloy introduces precise micro-additions of 0.3% Molybdenum and 0.8% Nickel into the titanium matrix. This intentional metallurgical profile significantly upgrades the material's properties, offering an extremely cost-effective alternative to expensive palladium-bearing grades (like Grade 7 and 11) while offering superior performance compared to Commercially Pure (CP) titanium options.
The introduction of Nickel and Molybdenum provides solid-solution strengthening, allowing Grade 12 to exhibit twice the mechanical strength of CP Grade 1 and comfortably exceed Grade 2 limits at elevated temperatures up to 300°C (570°F). More importantly, these elements alter the surface electrochemistry, granting the alloy exceptional resistance to localized crevice corrosion and pitting in hot, acidic chloride environments. This makes UNS R53400 fasteners an indispensable, high-reliability choice for marine heat exchangers, chemical processing autoclaves, and aggressive hydrometallurgical leaching operations.
| Material Classification | Low-Alloy Near-Alpha Titanium (Ti-Mo-Ni Alloy) |
|---|---|
| UNS Designation | R53400 |
| Microstructure | Near-Alpha Matrix with Fine Intergranular Beta Phases |
| Magnetic State | Completely Non-Magnetic |
| Density | 4.51 g/cm³ (0.163 lb/in³) — Exceptionally Lightweight |
| Size Range | Metric: M3 to M48 | Imperial: #4 to 2" |
| Primary Attribute | High Elevated-Temperature Strength & Cost-Effective Crevice Corrosion Resistance |
Contains detailed high-temperature yield reduction curves (up to 315°C), comprehensive crevice corrosion threshold limits in hot acidic brines, and specialized anti-galling guidelines for heavy hex bolting assemblies.
⬇ DOWNLOAD DATASHEETIn high-temperature and highly acidic industrial applications, strict adherence to chemical specifications is mandatory to prevent premature joint failure. Ananka enforces complete, mill-level chemical traceability for all Titanium Grade 12 fasteners to verify the critical Molybdenum and Nickel balancing.
The unique performance of Grade 12 is achieved via subtle modification of the unalloyed titanium base. Nickel and Molybdenum act in tandem: Molybdenum stabilizes the oxide film in reducing conditions, while Nickel alters the cathodic reaction kinetics, encouraging fast self-healing of the passive layer inside tight thread gaps and flange crevices where oxygen is restricted.
| Titanium (Ti) | Nickel (Ni) | Molybdenum (Mo) | Iron (Fe) | Oxygen (O) | Carbon / Nitrogen |
|---|---|---|---|---|---|
| Balance (~98.3) | 0.60 – 0.90 | 0.20 – 0.40 | 0.30 Max | 0.25 Max | 0.08 Max / 0.03 Max |
| Mechanical Property | Typical Limits (Annealed Temper) |
|---|---|
| Tensile Strength | 70,000 psi (483 MPa) Minimum |
| Yield Strength (0.2% Offset) | 50,000 - 65,000 psi (345 - 450 MPa) |
| Elongation (in 2 inches) | 18% Minimum |
| Hardness (Brinell) | ~ 190 HB (approx. 90 HRB) |
| Standard / System | Designation |
|---|---|
| ASTM Specifications | ASTM B348 (Bar & Rod), ASTM F467 / F468 (Fasteners) |
| Common Trade Names | Ti-0.3Mo-0.8Ni, Grade 12 Titanium, Alloy 12 CP-Low |
| European Equivalent | EN 3.7105 |
| ASME Standard | SB-348 Grade 12 |
| Mating Bolts/Studs | Internal Threads (Nuts) | Washers / Sealing Gaskets |
|---|---|---|
| Grade 12 Titanium Heavy Hex Bolts | Grade 12 Titanium Heavy Hex Nuts | Grade 12 Flat Washers / PTFE |
Titanium Grade 12 possesses remarkable mechanical yield thresholds, allowing for high structural clamping force. However, like all titanium alloys, it features a highly active oxide film that causes intense thread galling (friction welding) if tightened dry. The application of premium, chloride-free, high-temperature anti-seize compounds or dry-film lubricants is strictly mandatory to protect the thread integrity during assembly.
| Nominal Diameter | Threads Per Inch (UNC) | Max Target Torque (in-lbs) — Lubricated | Max Target Torque (ft-lbs) — Lubricated |
|---|---|---|---|
| 1/4" | 20 | 60 - 70 | ~ 5.5 |
| 5/16" | 18 | 125 - 145 | ~ 11.0 |
| 3/8" | 16 | 220 - 250 | ~ 19.5 |
| 1/2" | 13 | 480 - 540 | ~ 42.5 |
Grade 2 is the standard workhorse of unalloyed titanium, but it has two primary engineering vulnerabilities: its mechanical strength drops off sharply at temperatures exceeding 200°C, and it is highly susceptible to crevice corrosion inside tight joints or under gaskets when exposed to hot chloride environments. Grade 12 adds Molybdenum and Nickel, which elevates its high-temperature tensile yield and eliminates its vulnerability to crevice attacks, providing an exceptional upgrade for heavy-duty process systems.
Grade 7 utilizes a Palladium (Pd) addition which provides the absolute maximum possible resistance to crevice corrosion in severe reducing acids. However, because Palladium is an extremely expensive precious metal, Grade 7 fasteners carry an astronomical price premium. Grade 12 replaces the Palladium with a precise blend of Molybdenum and Nickel. This results in nearly identical crevice corrosion resistance in most neutral-to-acidic chloride streams at a fraction of the raw material cost.
Yes. Grade 12 exhibits excellent weldability, and unlike highly alloyed aerospace grades like Grade 5, it does not require complex post-weld heat treatments. Standard titanium inert gas shielding rules apply (using pure Argon back-purges). In terms of machining, the inclusion of fine intergranular beta-phase crystals makes Grade 12 slightly less gummy than standard pure grades, allowing for clean thread cutting on automated CNC lathes when using rigid setups and high-pressure coolants.
