Tungsten Alloy W (99.95% CP Tungsten)-SR (Stress relieved)
Heat-treated state · default condition
UNS R07005 · ASTM B760 · GB W1
The standard stocked condition for tungsten rod, bar and electrodes — highest usable room-temperature strength with a fine deformed grain structure.
Values for the SR condition
Other W (99.95% CP Tungsten) tempers and conditions
W (99.95% CP Tungsten) is listed in 5 conditions; see the grade overview at W (99.95% CP Tungsten).
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Sintered | Lowest-cost blank for crucibles, weights and shielding where strength and surface finish are secondary; residual porosity ~2–5%. | 420 | 500 | 0 | 33 HRC | 27 % IACS |
Recrystallized / annealed | Use where dimensional stability at very high temperature (>1400 °C, vacuum/inert) matters more than room-temperature toughness — the material is fully brittle cold. | 450 | 550 | 0 | 35 HRC | 32 % IACS |
Forged / rotary-swaged bar and blocks | Heavy sections (crucibles, anodes, large shielding blocks) where the density and grain refinement of hot working are needed but full drawing is impractical. | 700 | 850 | 2 | 38 HRC | 31 % IACS |
SRDefaultThis page Stress relieved | The standard stocked condition for tungsten rod, bar and electrodes — highest usable room-temperature strength with a fine deformed grain structure. | 750 | 950 | 2 | 39 HRC | 31 % IACS |
Rolled sheet/plate/foil | Choose for shielding sheet, sputtering targets, boat/heat-shield stock and foil; strongest in the rolling direction, anisotropic and notch sensitive. | 1,000 | 1,200 | 3 | 42 HRC | 30 % IACS |
What is W (99.95% CP Tungsten)-SR?
W (99.95% CP Tungsten)-SR is W (99.95% CP Tungsten) heat treated to SR — the standard stocked condition for tungsten rod, bar and electrodes — highest usable room-temperature strength with a fine deformed grain structure. W (99.95% CP Tungsten)-SR has a yield strength of 750 MPa (109 ksi) and a tensile strength of 950 MPa (138 ksi) — weaker than 53% of tungsten alloy grades. Elongation at break is 2% and the elastic modulus is 400 GPa (58 Msi). W (99.95% CP Tungsten)-SR has a density of 19.25 g/cm³ (0.695 lb/in³), heavier than 76% of tungsten alloy grades. It melts at 3,422°C (6,192 °F).
W (99.95% CP Tungsten)-SR properties
Typical room-temperature values for W (99.95% CP Tungsten)-SR; 11 are specific to this condition. Other listed values are W (99.95% CP Tungsten) reference data and may not represent this condition. Bars are the position among tungsten alloy grades.
Physical3
W (99.95% CP Tungsten)-SR has a density of 19.25 g/cm³ (0.695 lb/in³), heavier than 76% of tungsten alloy grades. It melts at 3,422°C (6,192 °F).
Mechanical15
W (99.95% CP Tungsten)-SR has a yield strength of 750 MPa (109 ksi) and a tensile strength of 950 MPa (138 ksi) — weaker than 53% of tungsten alloy grades. Elongation at break is 2% and the elastic modulus is 400 GPa (58 Msi).
Thermal6
W (99.95% CP Tungsten)-SR is rated for continuous service to 1,200°C (2,192 °F). It conducts heat at 173 W/m·K (100 BTU/hr·ft·°F), better than 88% of tungsten alloy grades. Thermal expansion is 4.5 µm/m·K (2.5 µin/in·°F).
Electrical3
W (99.95% CP Tungsten)-SR conducts electricity at 31 % IACS, better than 83% of tungsten alloy grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), better than 64% of tungsten alloy grades.
Sustainability4
Producing a kilogram of W (99.95% CP Tungsten)-SR takes about 400 MJ of energy and emits 27 kg of CO₂ — more than 74% of tungsten alloy grades. Typical recycled content is 30%.
Manufacturability8
W (99.95% CP Tungsten)-SR's machinability is not recommended (12/100, better than 67% of tungsten alloy grades); weldability not recommended (12/100); formability not recommended (8/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with W (99.95% CP Tungsten)-SR
Is W (99.95% CP Tungsten) easy to machine?
Treat as a brittle hard metal: grind, EDM or wire-EDM wherever possible; if turning/milling, use rigid setups, sharp micrograin carbide or CBN, low speed with heavy positive rake, and preheat (200–400 °C) for interrupted cuts to avoid chipping.
Can W (99.95% CP Tungsten) be welded?
Electron-beam or GTAW under vacuum/high-purity argon only; the fusion and heat-affected zones recrystallize and are essentially brittle at room temperature, so mechanical fastening or vacuum brazing (Ni, Cu, Ag-Cu, active fillers) is preferred.
Can W (99.95% CP Tungsten) be formed, bent or molded?
No practical cold forming — bend, deep-draw or coin only above the ductile-to-brittle transition (typically 300–600 °C, hotter for thick or recrystallized stock); most shapes are made by PM pressing plus hot rolling/swaging or by grinding from blank.
What surface finishes work on W (99.95% CP Tungsten)?
Lap/diamond-polish for target and mirror surfaces; electropolishing in dilute NaOH is used for wire and probes; for oxidation protection above 500 °C apply silicide, CVD or electroless-Ni coatings — anodizing does not apply.
W (99.95% CP 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 |
|---|---|---|
| Mousual largest metallic impurity | ≤ 0.01 | 0 |
| C | ≤ 0 | 0 |
| Ohigher in sintered-only product | ≤ 0.01 | 0 |
| Fe | ≤ 0 | 0 |
| Ni | ≤ 0 | 0 |
| Si | ≤ 0 | 0 |
| Al | ≤ 0 | 8×10⁻⁴ |
| Ca | ≤ 0 | 5×10⁻⁴ |
| Mg | ≤ 0 | 5×10⁻⁴ |
| Cu | ≤ 5×10⁻⁴ | 2×10⁻⁴ |
| N | ≤ 0 | 5×10⁻⁴ |
| H | ≤ 5×10⁻⁴ | 2×10⁻⁴ |
| Wminimum on a metallic basis per ASTM B760 / GB/T 3875 | ≥ 99.95 (balance) | — |
W (99.95% CP Tungsten)-SR — frequently asked
What is W (99.95% CP Tungsten)-SR used for?
W (99.95% CP Tungsten)-SR is typically used for furnace heating elements, X-ray targets, radiation shielding, electrical contacts and sputtering targets. In short: highest melting point metal; dense radiation shielding; brittle at room temperature.
What is the yield strength of W (99.95% CP Tungsten)-SR?
W (99.95% CP Tungsten)-SR has a typical yield strength of 750 MPa (109 ksi) and a tensile strength of 950 MPa (138 ksi) — weaker than 53% of tungsten alloy grades. Strength varies by condition: see the 5 listed tempers.
Is W (99.95% CP Tungsten)-SR easy to machine?
Not especially — machinability is rated not recommended (12/100, better than 67% of tungsten alloy grades). Treat as a brittle hard metal: grind, EDM or wire-EDM wherever possible; if turning/milling, use rigid setups, sharp micrograin carbide or CBN, low speed with heavy positive rake, and preheat (200–400 °C) for interrupted cuts to avoid chipping.
Can W (99.95% CP Tungsten)-SR be welded?
Not readily — weldability is rated not recommended (12/100). Electron-beam or GTAW under vacuum/high-purity argon only; the fusion and heat-affected zones recrystallize and are essentially brittle at room temperature, so mechanical fastening or vacuum brazing (Ni, Cu, Ag-Cu, active fillers) is preferred.
What surface finishes work on W (99.95% CP Tungsten)-SR?
Lap/diamond-polish for target and mirror surfaces; electropolishing in dilute NaOH is used for wire and probes; for oxidation protection above 500 °C apply silicide, CVD or electroless-Ni coatings — anodizing does not apply.
Can W (99.95% CP Tungsten)-SR be formed, bent or molded?
No practical cold forming — bend, deep-draw or coin only above the ductile-to-brittle transition (typically 300–600 °C, hotter for thick or recrystallized stock); most shapes are made by PM pressing plus hot rolling/swaging or by grinding from blank.
What is the maximum service temperature of W (99.95% CP Tungsten)-SR?
W (99.95% CP Tungsten)-SR is rated for continuous use to about 1,200°C (2,192 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between W (99.95% CP Tungsten)-SR and W (99.95% CP Tungsten) SINT?
SR is the default condition — the standard stocked condition for tungsten rod, bar and electrodes — highest usable room-temperature strength with a fine deformed grain structure. SINT: lowest-cost blank for crucibles, weights and shielding where strength and surface finish are secondary; residual porosity ~2–5%. Yield strength is 750 MPa in SR versus 420 MPa in SINT.
Sources
- ASTM B760 — Standard Specification for Tungsten Plate, Sheet, and Foil — ASTM International (2022)
- ASTM B777 / UNS R07005 designation data — ASTM International (2021)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (Refractory Metals) — ASM International (1990)
- Tungsten sheet, rod and wire material properties — Plansee SE / Midwest Tungsten Service (2023)
- CRC Handbook of Chemistry and Physics — physical constants of tungsten — CRC Press (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.