Tungsten Class 2 is a tungsten-base high-density metal — a tungsten heavy alloy (WHA) — containing nominally 92.5% tungsten. This datasheet presents the material within the American (ASTM / AMS / UNS) standard system.
Tungsten heavy alloys are produced by powder metallurgy: pure tungsten powder is blended with a nickel-iron or nickel-copper binder, pressed and liquid-phase sintered to near-full density. ASTM B777 defines four classes distinguished by nominal tungsten content and density; This class contains about 92.5% tungsten and provides high ductility and good machinability, while still providing a density more than twice that of steel. Magnetic grades use an iron-bearing binder and non-magnetic grades use a copper-bearing binder. The combination of very high density, good machinability and useful mechanical strength makes the material valuable wherever a large mass must be packaged in a small volume.
Typical applications include ballast and counterweights, radiation shielding for medical and nuclear equipment, vibration-damping tool holders and boring bars, ordnance components, and aerospace balance weights.
| Property | Value | Unit |
|---|---|---|
| Density (nominal) | 17.5 | g/cm³ |
| Tungsten content (nominal) | 92.5 | wt % |
| Elastic modulus | 290 | GPa |
| Coefficient of thermal expansion (20–100 °C) | 5.4 | µm/m·°C |
| Thermal conductivity (20 °C) | 75 | W/m·K |
| Hardness | ~24–30 | HRC |
| Structure | Two-phase (W grains + binder) | — |
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Tungsten | W | 91.5 | 93.5 | Base element; provides density |
| Nickel + Iron or Nickel + Copper | Ni + Fe/Cu | Balance | — | Binder / matrix phase |
| Density (nominal) | — | 17.30 | 17.70 | Class 2 density band (g/cm³) |
Sintered condition, typical values for ASTM B777 Class 2.
| Condition | Property | Value |
|---|---|---|
| As-sintered | Tensile strength (UTS) | ≥620 MPa (90 ksi) |
| As-sintered | 0.2% yield strength | ≥520 MPa (75 ksi) |
| As-sintered | Elongation at break | ≥10 % |
| Worked (swaged / rolled) | Tensile strength (UTS) | up to ~960 MPa |
| — | Hardness | ~24–30 HRC |
Confirm against the mill test report. Higher-class material has greater density; cold work (swaging or rolling) raises strength.
| Environment | Performance | Notes |
|---|---|---|
| Atmospheric / general | Good | Stable in normal atmospheres |
| Aqueous (neutral) | Good | Binder phase governs behaviour |
| Oxidizing acids | Moderate | Binder may be attacked |
| Elevated temperature (air) | Limited | Tungsten oxidises above ~400 °C in air |
| Coating option | — | Plating/coating available for corrosion/abrasion |
Corrosion behaviour is dominated by the nickel-iron or nickel-copper binder phase; for aggressive service the material is often plated or coated.
A powder-metallurgy two-phase alloy; not strengthened by precipitation. Properties are set by sintering and optional working.
Stress Relief A post-sinter stress relief or hydrogen sinter-anneal is used to improve ductility and remove residual stress. Properties are otherwise developed by liquid-phase sintering and optional cold work (swaging or rolling); these alloys are not age-hardenable.
Fusion welding is not generally recommended; tungsten heavy alloys are most often joined mechanically or by brazing. The binder phase governs joinability.
| Joining Process | Applicability | Notes |
|---|---|---|
| Brazing | Good | Common; silver- or nickel-based filler |
| Mechanical fastening | Good | Threaded or pinned assemblies |
| Fusion welding | Not recommended | Risk of cracking and embrittlement |
Join by brazing or mechanical means; avoid fusion welding.
Machining Guidelines
| Parameter | Recommendation |
|---|---|
| Machinability | Good for a refractory material; best of the four classes |
| Tooling | Carbide or CBN; rigid setups |
| Coolant | Ample coolant |
Forming Processes
| Process | Notes |
|---|---|
| Cold forming | Limited; can be swaged or rolled to raise strength |
| Machining | Preferred route to final shape; near-net sintered blanks |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Aerospace / defense | Balance and ballast weights, ordnance | High density + machinability |
| Medical / nuclear | Radiation shielding, collimators | High density + shielding |
| Tooling | Boring bars, vibration-damping holders | Density + stiffness |
| Industrial | Counterweights, governor weights | Mass in small volume |
| Product Form | ASTM Standard | AMS / Other |
|---|---|---|
| Block, bar and rod | ASTM B777 (Class 2) | AMS 7725 |
| Plate and sheet (worked) | ASTM B777 (Class 2) | — |
| Machined components | ASTM B777 (Class 2) | MIL-T-21014 (legacy) |
| Grades | Magnetic (Ni-Fe) / Non-magnetic (Ni-Cu) | — |
92.5% tungsten heavy alloy. ASTM B777 Class 2.
| Class | W (nominal) % | Density g/cm³ | Property Trend | Best Used For |
|---|---|---|---|---|
| Tungsten Class 1 | 90 | ~17.0 | Highest ductility / machinability | Ballast, shielding where ductility matters |
| Tungsten Class 2 | 92.5 | ~17.5 | Higher density, good ductility | Counterweights, shielding |
| Tungsten Class 3 | 95 | ~18.0 | Higher density | Compact ballast, ordnance |
| Tungsten Class 4 | 97 | ~18.5 | Highest density of the four | Maximum-density components |
| Pure tungsten | ~100 | ~19.3 | Maximum density, brittle | High-temperature / electronic uses |




