COMPREHENSIVE TECHNICAL ANALYSIS AND DATASHEET OF UNS R05255 TANTALUM TA-10W FASTENERS
UNS R05255, globally recognized as Tantalum 10% Tungsten (Ta-10W or Alloy 60), is the ultimate high-strength refractory alloy. By heavily alloying the Tantalum matrix with a massive 10% Tungsten (W) addition, the material undergoes a staggering transformation. It develops nearly double the tensile yield strength of pure Tantalum while fully retaining the metal's legendary, glass-like immunity to boiling concentrated acids.
Ta-10W is an uncompromising material designed for the absolute extremes of engineering. Because it maintains immense structural rigidity at temperatures exceeding 2,000°C (3,600°F), it is heavily utilized in aerospace propulsion and hypersonic defense systems. In the chemical processing industry, Ta-10W fasteners are the apex choice for high-pressure, high-temperature acid reactors where pure Tantalum (R05200) or Ta-2.5W (R05252) would suffer from mechanical yielding or creep deformation.
■ Product Overview & Specifications
| Material Classification | Heavy Tungsten-Alloyed Refractory Metal (Ta-10W) |
|---|---|
| UNS Designation | R05255 |
| Microstructure | Body-Centered Cubic (BCC) Solid Solution |
| Magnetic State | Completely Non-Magnetic |
| Density | 16.69 g/cm³ (0.603 lb/in³) — Exceptionally Heavy |
| Size Range | Metric: M4 to M24 | Imperial: #8 to 1" (Custom CNC Only) |
| Primary Attribute | Ultimate High-Temperature Strength & Absolute Acid Immunity |
■ Proprietary Datasheet Download (GATED)
UNS R05255 Ta-10W Alloy — Complete Technical Datasheet
Contains highly restricted aerospace thermal-creep degradation charts (up to 2,500°C), specialized carbide tooling feed-rates for CNC thread cutting, and high-pressure chemical vessel torque loads.
⬇ DOWNLOAD DATASHEET■ MTC Integration Section
Because Ta-10W is utilized in explosive aerospace environments and lethal chemical processing, trace gas contamination (oxygen/nitrogen) must be strictly eliminated to prevent catastrophic brittle fracturing. Ananka ensures every lot is melted via stringent Electron Beam (EB) or Vacuum Arc Reduction (VAR) methods.
- EN 10204 Type 3.1: Validates the massive 9.0–11.0% Tungsten matrix, verifies that interstitial gases are kept below parts-per-million (ppm) limits, and certifies the fully annealed mechanical temper.
- EN 10204 Type 3.2: Routinely facilitated for strict defense department contracts, hypersonic vehicle propulsion systems, and ultra-high-pressure chemical reaction facilities requiring third-party testing oversight.
■ Chemical Composition
The R05255 specification replaces 10% of the Tantalum with Tungsten (W). Because Tungsten has the highest melting point of all metals, its solid-solution integration massively boosts the alloy's high-temperature rigidity and tensile strength while seamlessly maintaining the impenetrable chemical resistance of the base Tantalum.
| Tantalum (Ta) | Tungsten (W) | Niobium (Nb) | Oxygen (O) | Carbon (C) | Nitrogen (N) |
|---|---|---|---|---|---|
| Balance (~89.9) | 9.00 – 11.00 | 0.10 Max | 0.015 Max | 0.010 Max | 0.010 Max |
■ Mechanical Properties
| Mechanical Property | Typical Limits (Fully Annealed Temper) |
|---|---|
| Tensile Strength | 70,000 - 95,000 psi (480 - 655 MPa) |
| Yield Strength | 50,000 - 75,000 psi (345 - 515 MPa) |
| Elongation (in 2 inches) | 15% - 20% |
| Hardness (Rockwell B) | 85 - 95 HRB (approx. 160 HV) |
■ Equivalent Grades & Designations
| Standard / System | Designation |
|---|---|
| ASTM Specifications | ASTM B365 (Rod and Wire), ASTM B390 |
| Common Trade Names | Ta-10W, Alloy 60, Tantalum-Tungsten 10% |
| European Equivalent | TaW10 (Approximate) |
■ Applications & Industries
- Aerospace & Hypersonics: High-temperature retaining fasteners for rocket engine nozzles, combustion chambers, and exhaust shielding operating at temperatures where standard superalloys (like Inconel) melt.
- Extreme Chemical Processing: Heavy structural bolting for pressurized acid regeneration vessels and halogen synthesis reactors requiring total acid immunity under immense physical load.
- High-Temperature Furnaces: Fastening hardware for vacuum furnace heating elements and radiation shields where the metal must survive extreme heat without oxidizing or deforming.
■ Compatible Fastener Assemblies
| Mating Bolts/Studs | Internal Threads (Nuts) | Washers / Sealing Components |
|---|---|---|
| R05255 CNC Machined Heavy Hex Bolts | R05255 Precision Hex Nuts | Graphite or Virgin PTFE Washers |
■ Torque & Installation Guidelines
Due to the massive 10% Tungsten addition, Ta-10W is significantly stronger and more rigid than pure Tantalum or Ta-2.5W, allowing it to withstand much heavier torque loads. However, severe refractory thread galling remains a high risk. High-temperature graphite paste or premium PTFE lubricants must be utilized during installation to prevent cold-welding.
| Nominal Diameter | Threads Per Inch (UNC) | Max Target Torque (in-lbs) — Lubricated | Max Target Torque (ft-lbs) — Lubricated |
|---|---|---|---|
| 1/4" | 20 | 65 - 75 | ~ 5.5 |
| 3/8" | 16 | 180 - 210 | ~ 16.0 |
| 1/2" | 13 | 400 - 450 | ~ 35.0 |
| 3/4" | 10 | 1200 - 1400 | ~ 110.0 |
■ Frequently Asked Questions
1. If Ta-10W is so strong, why isn't it used for all Tantalum fasteners?
The 10% Tungsten addition drastically increases the material's strength, but it also destroys its machinability. Ta-10W is notoriously difficult to machine, cut, and thread, rapidly destroying cutting tools and galling heavily during CNC turning. Because manufacturing costs for Ta-10W are astronomically high, it is strictly reserved for applications where Pure Ta or Ta-2.5W simply cannot survive the structural load or heat.
2. Can Ta-10W fasteners be cold-headed or forged?
No. The 10% Tungsten content creates a highly rigid matrix that fiercely resists deformation at room temperature. If you attempt to cold-head Ta-10W into a bolt, the metal will fracture and tooling will shatter. Fasteners made from Ta-10W are exclusively manufactured via slow, highly specialized subtractive CNC machining from solid bar stock.
3. Does the Tungsten addition compromise the chemical resistance?
No. Tungsten is highly compatible with Tantalum and possesses exceptional chemical resistance in its own right. The Ta-10W alloy retains the same glass-like immunity to boiling hydrochloric, nitric, and sulfuric acids as pure Tantalum. However, it also shares the same critical vulnerability: it will be rapidly destroyed by Hydrofluoric Acid (HF) and hot strong alkalis.
