Refractory Metal 5N Tantalum (99.999%)-SR (Stress relieved)
Heat-treated state
Pick when moderate strength plus flatness/low residual stress are needed, e.g. thick target blanks and formed capacitor parts.
Values for the SR condition
Other 5N Tantalum (99.999%) tempers and conditions
5N Tantalum (99.999%) is listed in 3 conditions; see the grade overview at 5N Tantalum (99.999%).
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault vacuum recrystallization annealed plate/target blank | Standard supply condition for sputtering-target blanks and corrosion linings: fully recrystallized, fine uniform grain, maximum ductility. | 120 | 200 | 45 | 65 HB | 57 W/m·K |
SRThis page Stress relieved | Pick when moderate strength plus flatness/low residual stress are needed, e.g. thick target blanks and formed capacitor parts. | 240 | 300 | 22 | 105 HB | 13.5 % IACS |
Cold worked | Highest strength and stiffness-per-section; used for springs, thin strip and wire where subsequent annealing is not wanted. | 400 | 450 | 7 | 152 HB | 13.1 % IACS |
What is 5N Tantalum (99.999%)-SR?
5N Tantalum (99.999%)-SR is 5N Tantalum (99.999%) heat treated to SR — pick when moderate strength plus flatness/low residual stress are needed, e.g. thick target blanks and formed capacitor parts. 5N Tantalum (99.999%)-SR has a yield strength of 240 MPa (34.8 ksi) and a tensile strength of 300 MPa (43.5 ksi) — weaker than 76% of refractory metal grades. Elongation at break is 22% and the elastic modulus is 186 GPa (27 Msi). 5N Tantalum (99.999%)-SR has a density of 16.65 g/cm³ (0.602 lb/in³), heavier than 86% of refractory metal grades. It melts at 3,017°C (5,463 °F). Annealed is the default condition FabDigit quotes; SR is available on request or by drawing note.
Advantages
- Good corrosion resistance — 97/100, better than 97% of refractory metal grades
- Tough — resists crack growth — 90 MPa·√m (81.9 ksi·√in), better than 94% of refractory metal grades
Limitations
- Limited service temperature — 275°C (527 °F), worse than 99% of refractory metal grades
- High embodied carbon — 270 kg CO₂/kg, worse than 97% of refractory metal grades
- Heavy — 16.65 g/cm³ (0.602 lb/in³), worse than 86% of refractory metal grades
- Low strength — 240 MPa (34.8 ksi), worse than 76% of refractory metal grades
5N Tantalum (99.999%)-SR properties
Typical room-temperature values for 5N Tantalum (99.999%)-SR; 22 are specific to this condition. Other listed values are 5N Tantalum (99.999%) reference data and may not represent this condition. Bars are the position among refractory metal grades.
Physical3
5N Tantalum (99.999%)-SR has a density of 16.65 g/cm³ (0.602 lb/in³), heavier than 86% of refractory metal grades. It melts at 3,017°C (5,463 °F).
Mechanical13
5N Tantalum (99.999%)-SR has a yield strength of 240 MPa (34.8 ksi) and a tensile strength of 300 MPa (43.5 ksi) — weaker than 76% of refractory metal grades. Elongation at break is 22% and the elastic modulus is 186 GPa (27 Msi).
Thermal6
5N Tantalum (99.999%)-SR is rated for continuous service to 275°C (527 °F). It conducts heat at 56 W/m·K (32.4 BTU/hr·ft·°F), better than 67% of refractory metal grades. Thermal expansion is 6.5 µm/m·K (3.61 µin/in·°F).
Electrical3
5N Tantalum (99.999%)-SR conducts electricity at 13.5 % IACS, better than 72% of refractory metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (97/100), better than 97% of refractory metal grades.
Sustainability4
Producing a kilogram of 5N Tantalum (99.999%)-SR takes about 4,500 MJ of energy and emits 270 kg of CO₂ — more than 97% of refractory metal grades. Typical recycled content is 25%.
Manufacturability8
5N Tantalum (99.999%)-SR's machinability is poor (30/100, better than 54% of refractory metal grades); weldability good (58/100); formability good (60/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 5N Tantalum (99.999%)-SR
Is 5N Tantalum (99.999%) easy to machine?
Extremely gummy and prone to galling/built-up edge — use sharp, highly-positive carbide or HSS-Co tools, slow speeds (20–40 m/min), heavy feed, chlorinated or flood coolant, and never dwell; grind with SiC after acid pickling to avoid embedded iron.
Can 5N Tantalum (99.999%) be welded?
EB or GTAW in a purged glovebox/vacuum chamber only — any O2/N2/H2 pickup above ~300 °C embrittles the joint; no filler needed, keep interstitials below 100 ppm to retain ductility.
Can 5N Tantalum (99.999%) be formed, bent or molded?
Cold forms, deep-draws and rolls readily at room temperature with >90 % reduction between anneals; use clean tooling and lubricant free of chlorides/sulfur, and vacuum recrystallization-anneal at 1000–1300 °C to reset grain size for uniform sputter erosion.
What surface finishes work on 5N Tantalum (99.999%)?
Acid pickle (HNO3-HF) or CMP to remove machining smear before target bonding; anodizing in dilute phosphoric acid builds a Ta2O5 dielectric/colour film — plating is rarely used, and surface cleanliness (particles, Fe, Na) governs thin-film yield.
5N Tantalum (99.999%) 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 |
|---|---|---|
| Nb≤10 ppm; principal metallic impurity | ≤ 0 | 3×10⁻⁴ |
| W≤5 ppm | ≤ 5×10⁻⁴ | 2×10⁻⁴ |
| Mo≤3 ppm | ≤ 3×10⁻⁴ | 1×10⁻⁴ |
| Fe≤2 ppm | ≤ 2×10⁻⁴ | 5×10⁻⁵ |
| Ni≤2 ppm | ≤ 2×10⁻⁴ | 5×10⁻⁵ |
| Cr≤1 ppm | ≤ 1×10⁻⁴ | 3×10⁻⁵ |
| Ti≤1 ppm | ≤ 1×10⁻⁴ | 3×10⁻⁵ |
| Si≤2 ppm | ≤ 2×10⁻⁴ | 5×10⁻⁵ |
| U≤0.5 ppb; alpha-emitter control for semiconductor use | ≤ 5×10⁻⁸ | — |
| Th≤0.5 ppb | ≤ 5×10⁻⁸ | — |
| O≤50 ppm, interstitial (not counted in 5N metals basis) | ≤ 0.01 | 0 |
| C≤10 ppm | ≤ 0 | 5×10⁻⁴ |
| N≤10 ppm | ≤ 0 | 3×10⁻⁴ |
| H≤5 ppm | ≤ 5×10⁻⁴ | 1×10⁻⁴ |
| Ta99.999 % metals basis (gases excluded), GDMS-verified | ≥ 100 (balance) | — |
5N Tantalum (99.999%)-SR — frequently asked
What is 5N Tantalum (99.999%)-SR used for?
5N Tantalum (99.999%)-SR is typically used for semiconductor diffusion barrier films, sputtering targets, MLCC electrode materials and thin-film resistor coatings. In short: highest-purity tantalum grade; electron-beam melted, 5N; excellent cold formability.
What is the yield strength of 5N Tantalum (99.999%)-SR?
5N Tantalum (99.999%)-SR has a typical yield strength of 240 MPa (34.8 ksi) and a tensile strength of 300 MPa (43.5 ksi) — weaker than 76% of refractory metal grades. Strength varies by condition: see the 3 listed tempers.
Is 5N Tantalum (99.999%)-SR easy to machine?
Not especially — machinability is rated poor (30/100, better than 54% of refractory metal grades). Extremely gummy and prone to galling/built-up edge — use sharp, highly-positive carbide or HSS-Co tools, slow speeds (20–40 m/min), heavy feed, chlorinated or flood coolant, and never dwell; grind with SiC after acid pickling to avoid embedded iron.
Can 5N Tantalum (99.999%)-SR be welded?
Yes — weldability is rated good (58/100). EB or GTAW in a purged glovebox/vacuum chamber only — any O2/N2/H2 pickup above ~300 °C embrittles the joint; no filler needed, keep interstitials below 100 ppm to retain ductility.
What surface finishes work on 5N Tantalum (99.999%)-SR?
Acid pickle (HNO3-HF) or CMP to remove machining smear before target bonding; anodizing in dilute phosphoric acid builds a Ta2O5 dielectric/colour film — plating is rarely used, and surface cleanliness (particles, Fe, Na) governs thin-film yield.
Can 5N Tantalum (99.999%)-SR be formed, bent or molded?
Cold forms, deep-draws and rolls readily at room temperature with >90 % reduction between anneals; use clean tooling and lubricant free of chlorides/sulfur, and vacuum recrystallization-anneal at 1000–1300 °C to reset grain size for uniform sputter erosion.
What is the maximum service temperature of 5N Tantalum (99.999%)-SR?
5N Tantalum (99.999%)-SR is rated for continuous use to about 275°C (527 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 5N Tantalum (99.999%) Annealed and 5N Tantalum (99.999%)-CW?
Annealed is the default condition — standard supply condition for sputtering-target blanks and corrosion linings: fully recrystallized, fine uniform grain, maximum ductility. CW: highest strength and stiffness-per-section; used for springs, thin strip and wire where subsequent annealing is not wanted. Yield strength is 120 MPa in Annealed versus 400 MPa in CW.
Sources
- ASTM B708 — Tantalum and Tantalum Alloy Plate, Sheet and Strip — ASTM International (2021)
- ASTM B365 — Tantalum and Tantalum Alloy Rod and Wire — ASTM International (2018)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (Refractory Metals) — ASM International (1990)
- CRC Handbook of Chemistry and Physics — Physical Properties of the Elements — CRC Press (2023)
- High-purity tantalum sputtering target blanks (EB-melted, 99.999 %) — Global Advanced Metals / H.C. Starck / (2023)
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.