Tungsten Heavy Alloy (B777)
A heavy, machinable tungsten alloy
Typical values for the temper in the title
Tungsten heavy alloy (WHA) is made by powder metallurgy: tungsten particles bonded in a nickel-iron or nickel-copper matrix. Unlike pure tungsten, which is brittle and hard to machine, it is ductile and machinable, while still very dense (about 16.85–18.85 g/cm³, about 50% more than lead).
ASTM B777 defines four classes: Class 1 (90% W) to Class 4 (97% W). The more tungsten, the higher the density and stiffness and the lower the ductility. It is used for balance weights in aircraft and rotating tools, radiation shielding in medicine and industry, and vibration damping.
Mechanical and physical properties
| Property | Value | Note |
|---|---|---|
| Tensile strength Rm | ≥690–758 MPa (by Class) | |
| Modulus of elasticity E | 310–359 GPa | |
| Density ρ | 16.85–18.85 g/cm³ | by Class (ASTM B777) |
| Machinability | Relatively good — machinable | relative rating in the site database |
Chemical composition (wt %)
| Element | Range | Role |
|---|---|---|
| W tungsten | 90–97 (by Class) | density |
| Ni nickel | binder | ductility |
| Fe / Cu | binder | Fe: magnetic; Cu: non-magnetic |
Per ASTM B777: Class 1 = 90%, Class 2 = 92.5%, Class 3 = 95%, Class 4 = 97% tungsten (nominal). Density and maximum hardness per the standard.
Conditions and product forms
The class is chosen by required density. Where magnetism is not allowed, order a non-magnetic grade (nickel-copper binder); Class 4 exists only in a magnetic version.
| Condition | Properties | When to choose it |
|---|---|---|
| Class 1 (90% W) | density 16.85–17.25, more ductile | loaded parts |
| Class 2 (92.5% W) | density 17.15–17.85 | general use |
| Class 3 (95% W) | density 17.75–18.35 | weights and shielding |
| Class 4 (97% W) | density 18.25–18.85, magnetic only | maximum density |
Applications
- Balance weights
- Radiation shielding
- Rotating inertia parts
- Vibration damping
- Weights in sporting goods
Fabrication
Machining
Machinable with carbide tools, unlike pure tungsten. The dust is harmful, so work with extraction.
Magnetism
Ni-Fe grades are magnetic. For use near sensors or magnets, order a non-magnetic grade.
Joining
Not welded. Join mechanically or by brazing.
Compared with similar materials
| Material | Rm / Rp0.2 | Welding | When it is the better choice |
|---|---|---|---|
| Tungsten (W) | 980–1510 / 760–1170 MPa | Electron beam / TIG with care | pure tungsten: slightly denser, brittle and hard to machine · material page |
| Copper-Tungsten (W-Cu) | 585–654 MPa (Class D) / | No — brazing | copper-tungsten: for electrodes and contacts · material page |
| Molybdenum (Mo) | 700 / 560 MPa | Electron beam / laser | molybdenum: refractory and lighter · material page |
Common mistakes
Ordering Class 4 when non-magnetic is required
Class 4 exists only magnetic.
Using lead for shielding in a mechanical part
The heavy alloy is strong, does not creep and is not toxic like lead.
Confusing it with pure tungsten
The alloy is machinable; pure tungsten is not.
Equivalents, standards and supply
| ASTM | B777 Class 1–4 |
|---|---|
| Standards | ASTM B777 |
| Forms | bar · plate · block · finished parts |
| Producers | Plansee · ATI · Wolfmet |
Learn more
Values are typical and for comparison only. For design, rely on the standard, the producer specification and the mill certificate. Sources: ASTM standards (B86, B386, B392/B393, B551, B708, B760 and others), producer data, and the METAL HUB materials database.
Updated: October 31, 2026