Tungsten Alloy WVMA (Doped Non-Sag Tungsten) AD-BK
Finish state
ASTM F288 · also AKS Tungsten
AD-BK = as-drawn, black (graphite-coated) wire
Cheapest form — drawing graphite left on the surface; pick it when the wire will be cleaned, coiled and hydrogen-fired by the user.
Values for the AD-BK condition
Other WVMA (Doped Non-Sag Tungsten) tempers and conditions
WVMA (Doped Non-Sag Tungsten) is listed in 5 conditions; see the grade overview at WVMA (Doped Non-Sag Tungsten).
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Recrystallised | Condition after flashing/service above ~2000 °C: long interlocked grains give the sag resistance the doping is designed for, but the wire is brittle at room temperature. | 600 | 700 | 1 | 36 HRC | 32.5 % IACS |
Swaged / ground rod | Larger diameters produced by rotary swaging and ground to size — for electrodes, furnace hooks, supports and evaporation sources needing sag resistance. | 1,000 | 1,200 | 2 | 43 HRC | 32 % IACS |
Stress relieved | Wire annealed ~1000–1400 °C in hydrogen to relieve drawing stresses and give straight, spring-free wire for probes, supports and precision heaters. | 1,400 | 1,750 | 3.5 | 43 HRC | 32 % IACS |
AD-CLDefault As-drawn, cleaned (bright) wire | Standard stock condition: cold-drawn doped wire with the graphite drawing lubricant chemically/electrolytically removed — for filament coiling, heaters and probe wire. | 1,900 | 2,200 | 2.5 | 48 HRC | 31 % IACS |
AD-BKThis page As-drawn, black (graphite-coated) wire | Cheapest form — drawing graphite left on the surface; pick it when the wire will be cleaned, coiled and hydrogen-fired by the user. | 1,900 | 2,200 | 2.5 | 48 HRC | 31 % IACS |
What is WVMA (Doped Non-Sag Tungsten) AD-BK?
WVMA (Doped Non-Sag Tungsten) AD-BK is WVMA (Doped Non-Sag Tungsten) supplied in the AD-BK condition — cheapest form — drawing graphite left on the surface; pick it when the wire will be cleaned, coiled and hydrogen-fired by the user. WVMA (Doped Non-Sag Tungsten) AD-BK has a yield strength of 1,900 MPa (276 ksi) and a tensile strength of 2,200 MPa (319 ksi) — stronger than 100% of tungsten alloy grades. Elongation at break is 2.5% and the elastic modulus is 400 GPa (58 Msi). WVMA (Doped Non-Sag Tungsten) AD-BK has a density of 19.3 g/cm³ (0.697 lb/in³), heavier than 90% of tungsten alloy grades. It melts at 3,422°C (6,192 °F). AD-CL is the default condition FabDigit quotes; AD-BK is available on request or by drawing note.
Advantages
- High strength — 1,900 MPa (276 ksi), better than 100% of tungsten alloy grades
- Forms and bends easily — 25/100, better than 90% of tungsten alloy grades
- Low embodied carbon — 22 kg CO₂/kg, better than 79% of tungsten alloy grades
- High service temperature — 2,000°C (3,632 °F), better than 76% of tungsten alloy grades
Limitations
- Hard to polish — 55/100, worse than 98% of tungsten alloy grades
WVMA (Doped Non-Sag Tungsten) AD-BK properties
Typical room-temperature values for WVMA (Doped Non-Sag Tungsten) AD-BK; 21 are specific to this condition. Other listed values are WVMA (Doped Non-Sag Tungsten) reference data and may not represent this condition. Bars are the position among tungsten alloy grades.
Physical3
WVMA (Doped Non-Sag Tungsten) AD-BK has a density of 19.3 g/cm³ (0.697 lb/in³), heavier than 90% of tungsten alloy grades. It melts at 3,422°C (6,192 °F).
Mechanical16
WVMA (Doped Non-Sag Tungsten) AD-BK has a yield strength of 1,900 MPa (276 ksi) and a tensile strength of 2,200 MPa (319 ksi) — stronger than 100% of tungsten alloy grades. Elongation at break is 2.5% and the elastic modulus is 400 GPa (58 Msi).
Thermal6
WVMA (Doped Non-Sag Tungsten) AD-BK is rated for continuous service to 2,000°C (3,632 °F). It conducts heat at 168 W/m·K (97.1 BTU/hr·ft·°F), better than 76% of tungsten alloy grades. Thermal expansion is 4.5 µm/m·K (2.5 µin/in·°F).
Electrical3
WVMA (Doped Non-Sag Tungsten) AD-BK conducts electricity at 31 % IACS, better than 83% of tungsten alloy grades.
Chemical & Environmental2
Corrosion resistance is good (60/100), better than 50% of tungsten alloy grades.
Sustainability4
Producing a kilogram of WVMA (Doped Non-Sag Tungsten) AD-BK takes about 380 MJ of energy and emits 22 kg of CO₂ — less than 62% of tungsten alloy grades. Typical recycled content is 30%.
Manufacturability7
WVMA (Doped Non-Sag Tungsten) AD-BK's machinability is not recommended (12/100, better than 67% of tungsten alloy grades); weldability poor (15/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with WVMA (Doped Non-Sag Tungsten) AD-BK
Is WVMA (Doped Non-Sag Tungsten) easy to machine?
Effectively unmachinable by conventional turning; use wire/sinker EDM, grinding with diamond or resin-bonded SiC, and abrasive or laser cutting — never shear recrystallised wire cold.
Can WVMA (Doped Non-Sag Tungsten) be welded?
Fusion welding embrittles by recrystallisation and gas pickup; join by resistance/spot welding, laser microwelding, or braze with Ni, Cu-Ag or Zr-active fillers in vacuum/hydrogen.
Can WVMA (Doped Non-Sag Tungsten) be formed, bent or molded?
Fine wire can be coiled at room temperature; larger diameters and tight-pitch coils must be warm-formed at 300–800 °C over a Mo mandrel that is later dissolved in acid.
What surface finishes work on WVMA (Doped Non-Sag Tungsten)?
Supplied black (graphite) or electrolytically cleaned bright; hydrogen firing removes carbon, and Ni/Cu/Au plating is used to aid soldering — no anodising, protect from air above ~400 °C.
WVMA (Doped Non-Sag Tungsten) chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Kretained potassium from K–Si–Al doping, 50–100 ppm; the bubble-forming dopant | 0.01 | 0.01 |
| Siresidual from potassium silicate dopant | 2×10⁻⁴ – 0 | 8×10⁻⁴ |
| Alresidual from aluminium chloride dopant | 2×10⁻⁴ – 0 | 0 |
| Motypical impurity limit | ≤ 0.01 | — |
| Fe | ≤ 0 | — |
| O | ≤ 0.01 | — |
| C | ≤ 0 | — |
| W≥99.95 % excluding dopants, per ASTM F288 / GB/T 4181 | balance | — |
WVMA (Doped Non-Sag Tungsten) AD-BK — frequently asked
What is WVMA (Doped Non-Sag Tungsten) AD-BK used for?
WVMA (Doped Non-Sag Tungsten) AD-BK is typically used for incandescent lamp filaments, vacuum tube heaters, halogen lamp coils and resistance heating wire. In short: non-sag doped tungsten wire; standard filament coil wire; highest strength in family.
What is the yield strength of WVMA (Doped Non-Sag Tungsten) AD-BK?
WVMA (Doped Non-Sag Tungsten) AD-BK has a typical yield strength of 1,900 MPa (276 ksi) and a tensile strength of 2,200 MPa (319 ksi) — stronger than 100% of tungsten alloy grades. Strength varies by condition: see the 5 listed tempers.
Is WVMA (Doped Non-Sag Tungsten) AD-BK easy to machine?
Not especially — machinability is rated not recommended (12/100, better than 67% of tungsten alloy grades). Effectively unmachinable by conventional turning; use wire/sinker EDM, grinding with diamond or resin-bonded SiC, and abrasive or laser cutting — never shear recrystallised wire cold.
Can WVMA (Doped Non-Sag Tungsten) AD-BK be welded?
Not readily — weldability is rated poor (15/100). Fusion welding embrittles by recrystallisation and gas pickup; join by resistance/spot welding, laser microwelding, or braze with Ni, Cu-Ag or Zr-active fillers in vacuum/hydrogen.
What surface finishes work on WVMA (Doped Non-Sag Tungsten) AD-BK?
Supplied black (graphite) or electrolytically cleaned bright; hydrogen firing removes carbon, and Ni/Cu/Au plating is used to aid soldering — no anodising, protect from air above ~400 °C.
Can WVMA (Doped Non-Sag Tungsten) AD-BK be formed, bent or molded?
Fine wire can be coiled at room temperature; larger diameters and tight-pitch coils must be warm-formed at 300–800 °C over a Mo mandrel that is later dissolved in acid.
What is the maximum service temperature of WVMA (Doped Non-Sag Tungsten) AD-BK?
WVMA (Doped Non-Sag Tungsten) AD-BK is rated for continuous use to about 2,000°C (3,632 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between WVMA (Doped Non-Sag Tungsten) AD-CL and WVMA (Doped Non-Sag Tungsten)-RX?
AD-CL is the default condition — standard stock condition: cold-drawn doped wire with the graphite drawing lubricant chemically/electrolytically removed — for filament coiling, heaters and probe wire. RX: condition after flashing/service above ~2000 °C: long interlocked grains give the sag resistance the doping is designed for, but the wire is brittle at room temperature. Yield strength is 1,900 MPa in AD-CL versus 600 MPa in RX.
Sources
- ASTM F288 — Standard Specification for Tungsten Wire for Electron Devices and Lamps — ASTM International (2018)
- GB/T 4181 — (Tungsten wire) (2017)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (Refractory Metals) — ASM International (1990)
- Doped (non-sag) tungsten wire and filament data — Plansee / Osram Sylvania / (2023)
- Refractory metal property and eco-property data — Granta/CES-type materials database (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.