Tungsten Alloy Class 4 Tungsten W-25Re-ANN
Heat-treated state
ASTM B760 Class 4
Fully annealed (vacuum/H₂, ~1600–1800 °C) for maximum machinability and dimensional stability before long high-temperature service; strength drops sharply.
Values for the W-25Re-ANN condition
Other Class 4 Tungsten tempers and conditions
Class 4 Tungsten is listed in 7 conditions; see the grade overview at Class 4 Tungsten.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
W-25Re | Pressed-and-sintered (or HIP) blank supplied for subsequent grinding/EDM into crucibles, targets and emitter bodies; lower strength and slight residual porosity. | 500 | 620 | 2 | 39 HRC | 4.8 % IACS |
W-25Re-ANNThis page W-25Re | Fully annealed (vacuum/H₂, ~1600–1800 °C) for maximum machinability and dimensional stability before long high-temperature service; strength drops sharply. | 620 | 950 | 22 | 400 HV | — |
W-3Re | Lowest-rhenium (cheapest) W-Re; positive leg of Type D thermocouples and high-temperature structural wire where melting point matters more than ductility. | 1,050 | 1,350 | 8 | 460 HV | 18 % IACS |
W-5Re | Type C thermocouple positive leg; good compromise of near-tungsten melting point with usable room-temperature ductility. | 1,150 | 1,450 | 9 | 490 HV | 13.8 % IACS |
W-25Re-SRDefault W-25Re | Most widely stocked structural W-Re condition: maximum room-temperature ductility and strength for thermocouples, ion-source parts and X-ray targets. | 1,400 | 1,800 | 12 | 55 HRC | 5.5 % IACS |
W-26Re | Type C thermocouple negative leg and highest-ductility W-Re; pick when bendability and weldability matter most. | 1,450 | 1,900 | 14 | 620 HV | 5.4 % IACS |
W-26Re | As-drawn thermocouple / emitter wire in the highest-strength work-hardened condition; use where tensile strength and springiness govern, not ductility. | 2,500 | 3,000 | 3 | 60 HRC | 5.2 % IACS |
What is Class 4 Tungsten W-25Re-ANN?
Class 4 Tungsten W-25Re-ANN is Class 4 Tungsten heat treated to W-25Re-ANN — fully annealed (vacuum/H₂, ~1600–1800 °C) for maximum machinability and dimensional stability before long high-temperature service; strength drops sharply. Class 4 Tungsten W-25Re-ANN has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 950 MPa (138 ksi) — weaker than 67% of tungsten alloy grades. Elongation at break is 22% and the elastic modulus is 400 GPa (58 Msi). Class 4 Tungsten W-25Re-ANN has a density of 19.7 g/cm³ (0.712 lb/in³), heavier than 98% of tungsten alloy grades. It melts at 3,120°C (5,648 °F). W-25Re-SR is the default condition FabDigit quotes; W-25Re-ANN is available on request or by drawing note.
Advantages
- Ductile — tolerates forming and impact — 22%, better than 105% of tungsten alloy grades
- Forms and bends easily — 38/100, better than 105% of tungsten alloy grades
- Readily welded — 45/100, better than 100% of tungsten alloy grades
- High service temperature — 2,400°C (4,352 °F), better than 86% of tungsten alloy grades
- Tough — resists crack growth — 30 MPa·√m (27.3 ksi·√in), better than 81% of tungsten alloy grades
Limitations
- Low electrical conductivity — 5.5 % IACS, worse than 100% of tungsten alloy grades
- Poor heat conductor — 46 W/m·K (26.6 BTU/hr·ft·°F), worse than 95% of tungsten alloy grades
- High embodied carbon — 34 kg CO₂/kg, worse than 95% of tungsten alloy grades
Class 4 Tungsten W-25Re-ANN properties
Typical room-temperature values for Class 4 Tungsten W-25Re-ANN; 10 are specific to this condition. Other listed values are Class 4 Tungsten reference data and may not represent this condition. Bars are the position among tungsten alloy grades.
Physical3
Class 4 Tungsten W-25Re-ANN has a density of 19.7 g/cm³ (0.712 lb/in³), heavier than 98% of tungsten alloy grades. It melts at 3,120°C (5,648 °F).
Mechanical14
Class 4 Tungsten W-25Re-ANN has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 950 MPa (138 ksi) — weaker than 67% of tungsten alloy grades. Elongation at break is 22% and the elastic modulus is 400 GPa (58 Msi).
Thermal6
Class 4 Tungsten W-25Re-ANN is rated for continuous service to 2,400°C (4,352 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), worse than 95% of tungsten alloy grades. Thermal expansion is 4.6 µm/m·K (2.56 µin/in·°F).
Electrical3
Class 4 Tungsten W-25Re-ANN conducts electricity at 5.5 % IACS, worse than 100% of tungsten alloy grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), better than 64% of tungsten alloy grades.
Sustainability4
Producing a kilogram of Class 4 Tungsten W-25Re-ANN takes about 520 MJ of energy and emits 34 kg of CO₂ — more than 95% of tungsten alloy grades. Typical recycled content is 20%.
Manufacturability8
Class 4 Tungsten W-25Re-ANN's machinability is not recommended (12/100, better than 67% of tungsten alloy grades); weldability fair (45/100); formability fair (38/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Class 4 Tungsten W-25Re-ANN
Is Class 4 Tungsten easy to machine?
Treat as a hard refractory metal: grind, wire-EDM or use rigid setups with negative-rake carbide/PCD at low speed and high feed; preheat or anneal to avoid chipping, and never dry-grind (WO₃ dust hazard).
Can Class 4 Tungsten be welded?
Electron-beam or laser welding in vacuum, or GTAW in a purged glovebox with high-purity Ar; rhenium keeps welds far more ductile than pure W, but keep O/N/C pickup near zero and post-weld stress relieve.
Can Class 4 Tungsten be formed, bent or molded?
Work warm (typically 300–1200 °C depending on Re content and section); fine wire and thin foil of W-25/26Re can be cold bent, heavy sections crack below the DBTT.
What surface finishes work on Class 4 Tungsten?
No anodizing; use electropolishing or diamond lapping for emitter surfaces, and Si/Ir/Re-base or CVD coatings if any exposure to air above ~450 °C is unavoidable.
Class 4 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 |
|---|---|---|
| ReGrade family covers W-3Re, W-5Re, W-25Re and W-26Re; default variant is nominal 25 % Re (24.0–26.0) | 3 – 26 | 25 |
| Moimpurity limit | ≤ 0.02 | — |
| Feimpurity limit | ≤ 0.01 | — |
| Niimpurity limit | ≤ 0.01 | — |
| Cimpurity limit | ≤ 0.01 | — |
| Oimpurity limit | ≤ 0.01 | — |
| Nimpurity limit | ≤ 0 | — |
| Siimpurity limit | ≤ 0 | — |
| Wbalance, 99.95 % min purity basis before Re addition | balance | — |
Class 4 Tungsten W-25Re-ANN — frequently asked
What is Class 4 Tungsten W-25Re-ANN used for?
Class 4 Tungsten W-25Re-ANN is typically used for thermocouple wire (W-Re type C), X-ray tube targets, aerospace high-temperature components and nuclear and plasma facing components. In short: most ductile tungsten class; weldable refractory tungsten; highest strength, highest cost.
What is the yield strength of Class 4 Tungsten W-25Re-ANN?
Class 4 Tungsten W-25Re-ANN has a typical yield strength of 620 MPa (89.9 ksi) and a tensile strength of 950 MPa (138 ksi) — weaker than 67% of tungsten alloy grades. Strength varies by condition: see the 7 listed tempers.
Is Class 4 Tungsten W-25Re-ANN easy to machine?
Not especially — machinability is rated not recommended (12/100, better than 67% of tungsten alloy grades). Treat as a hard refractory metal: grind, wire-EDM or use rigid setups with negative-rake carbide/PCD at low speed and high feed; preheat or anneal to avoid chipping, and never dry-grind (WO₃ dust hazard).
Can Class 4 Tungsten W-25Re-ANN be welded?
With care — weldability is rated fair (45/100). Electron-beam or laser welding in vacuum, or GTAW in a purged glovebox with high-purity Ar; rhenium keeps welds far more ductile than pure W, but keep O/N/C pickup near zero and post-weld stress relieve.
What surface finishes work on Class 4 Tungsten W-25Re-ANN?
No anodizing; use electropolishing or diamond lapping for emitter surfaces, and Si/Ir/Re-base or CVD coatings if any exposure to air above ~450 °C is unavoidable.
Can Class 4 Tungsten W-25Re-ANN be formed, bent or molded?
Work warm (typically 300–1200 °C depending on Re content and section); fine wire and thin foil of W-25/26Re can be cold bent, heavy sections crack below the DBTT.
What is the maximum service temperature of Class 4 Tungsten W-25Re-ANN?
Class 4 Tungsten W-25Re-ANN is rated for continuous use to about 2,400°C (4,352 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASTM B760 — Tungsten Plate, Sheet, and Foil — ASTM International (2017)
- ASTM F288 — Tungsten and Tungsten Alloy Wire for Electron Devices and Lamps — ASTM International (2017)
- GB/T 4187 — / (tungsten and tungsten alloy bar) (2017)
- Tungsten-Rhenium Alloy (W-3Re, W-25Re, W-26Re) product data — Rhenium Alloys, Inc. (2023)
- Tungsten and tungsten alloys material properties — Plansee SE (2023)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (Refractory Metals) — ASM International (1990)
- CRC Handbook of Chemistry and Physics (W, Re thermophysical data) — CRC Press (2020)
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.