Refractory Metal T-111-SR (Stress relieved)
Heat-treated state
UNS R05340 · ASTM B364
Choose when higher room-temperature strength is needed but residual cold-work stresses must be removed before service.
Values for the SR condition
Other T-111 tempers and conditions
T-111 is listed in 5 conditions; see the grade overview at T-111.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Ingot or cast-shape condition supplied for further working or for non-critical high-temperature hardware; coarse grain lowers strength and ductility. | 380 | 500 | 18 | 208 HB | 6.9 % IACS |
As-welded deposit | Property basis for weld joints — T-111 welds retain good ductility provided the chamber atmosphere is oxygen/nitrogen free. | 400 | 540 | 18 | 225 HB | 6.9 % IACS |
AnnealedDefault Annealed (recrystallized, vacuum 1500–1650 °C) | Standard stocked condition for sheet, plate, rod and tube — maximum ductility and formability, best for forming and welding. | 415 | 550 | 25 | 21 HRC | 6.9 % IACS |
SRThis page Stress relieved | Choose when higher room-temperature strength is needed but residual cold-work stresses must be removed before service. | 620 | 720 | 15 | 28 HRC | 6.8 % IACS |
Cold worked | Highest room-temperature strength and hardness for springs, fasteners and thin foil; strength is lost on exposure above ~1300 °C. | 830 | 900 | 8 | 32 HRC | 6.7 % IACS |
What is T-111-SR?
T-111-SR is T-111 heat treated to SR — choose when higher room-temperature strength is needed but residual cold-work stresses must be removed before service. T-111-SR has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 720 MPa (104 ksi) — stronger than 84% of refractory metal grades. Elongation at break is 15% and the elastic modulus is 200 GPa (29 Msi). T-111-SR has a density of 16.8 g/cm³ (0.607 lb/in³), heavier than 89% of refractory metal grades. It melts at 3,030°C (5,486 °F). Annealed is the default condition FabDigit quotes; SR is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 75 MPa·√m (68.3 ksi·√in), better than 88% of refractory metal grades
- High strength — 620 MPa (89.9 ksi), better than 84% of refractory metal grades
- High service temperature — 1,400°C (2,552 °F), better than 81% of refractory metal grades
- Readily welded — 75/100, better than 81% of refractory metal grades
Limitations
- High embodied carbon — 265 kg CO₂/kg, worse than 95% of refractory metal grades
- Heavy — 16.8 g/cm³ (0.607 lb/in³), worse than 89% of refractory metal grades
T-111-SR properties
Typical room-temperature values for T-111-SR; 22 are specific to this condition. Other listed values are T-111 reference data and may not represent this condition. Bars are the position among refractory metal grades.
Physical3
T-111-SR has a density of 16.8 g/cm³ (0.607 lb/in³), heavier than 89% of refractory metal grades. It melts at 3,030°C (5,486 °F).
Mechanical17
T-111-SR has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 720 MPa (104 ksi) — stronger than 84% of refractory metal grades. Elongation at break is 15% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
T-111-SR is rated for continuous service to 1,400°C (2,552 °F). It conducts heat at 41 W/m·K (23.7 BTU/hr·ft·°F), worse than 53% of refractory metal grades. Thermal expansion is 6.5 µm/m·K (3.61 µin/in·°F).
Electrical3
T-111-SR conducts electricity at 6.8 % IACS, better than 52% of refractory metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (93/100), better than 92% of refractory metal grades.
Sustainability3
Producing a kilogram of T-111-SR takes about 4,400 MJ of energy and emits 265 kg of CO₂ — more than 94% of refractory metal grades. Typical recycled content is 20%.
Manufacturability8
T-111-SR's machinability is poor (28/100, worse than 58% of refractory metal grades); weldability very good (75/100); formability fair (50/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with T-111-SR
Is T-111 easy to machine?
Machines like a soft gummy metal: slow speeds, heavy positive-rake sharp carbide, rigid setups, generous chlorinated or sulfurised coolant to stop galling and built-up edge; degrease and etch after machining to remove embedded contaminants.
Can T-111 be welded?
GTAW or EB weld in high-purity argon glove box or vacuum only — any O2/N2/H2 pickup embrittles the joint; no filler needed, clean with acid pickle and vacuum degas before welding.
Can T-111 be formed, bent or molded?
Excellent cold formability in the annealed state (bending, deep drawing, spinning); anneal at 1450–1650 °C in vacuum between heavy passes and never form or heat in air above ~300 °C.
What surface finishes work on T-111?
Chemical polish or electropolish in HF/HNO3-based baths; no decorative anodize or plating is normally applied, and iridium/silicide coatings are used only when short air exposure at temperature is unavoidable.
T-111 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 |
|---|---|---|
| Wsolid-solution strengthener | 7 – 9 | 8 |
| Hfoxygen getter / carbide-forming strengthener | 1.8 – 2.4 | 2 |
| Nb | ≤ 0.5 | — |
| Mo | ≤ 0.02 | — |
| Ti | ≤ 0.02 | — |
| Fe | ≤ 0.01 | — |
| Ni | ≤ 0.01 | — |
| Si | ≤ 0.01 | — |
| C | ≤ 0.01 | — |
| Ointerstitials control ductility | ≤ 0.02 | — |
| N | ≤ 0.01 | — |
| H | ≤ 0 | — |
| Ta | balance | — |
T-111-SR — frequently asked
What is T-111-SR used for?
T-111-SR is typically used for nuclear reactor components, rocket thruster liners, high-temperature furnace fixtures and space power system heat exchangers. In short: high-creep-strength tantalum alloy; ductile above 1300 °C; vacuum or inert service only.
What is the yield strength of T-111-SR?
T-111-SR has a typical yield strength of 620 MPa (89.9 ksi) and a tensile strength of 720 MPa (104 ksi) — stronger than 84% of refractory metal grades. Strength varies by condition: see the 5 listed tempers.
Is T-111-SR easy to machine?
Not especially — machinability is rated poor (28/100, worse than 58% of refractory metal grades). Machines like a soft gummy metal: slow speeds, heavy positive-rake sharp carbide, rigid setups, generous chlorinated or sulfurised coolant to stop galling and built-up edge; degrease and etch after machining to remove embedded contaminants.
Can T-111-SR be welded?
Yes — weldability is rated very good (75/100). GTAW or EB weld in high-purity argon glove box or vacuum only — any O2/N2/H2 pickup embrittles the joint; no filler needed, clean with acid pickle and vacuum degas before welding.
What surface finishes work on T-111-SR?
Chemical polish or electropolish in HF/HNO3-based baths; no decorative anodize or plating is normally applied, and iridium/silicide coatings are used only when short air exposure at temperature is unavoidable.
Can T-111-SR be formed, bent or molded?
Excellent cold formability in the annealed state (bending, deep drawing, spinning); anneal at 1450–1650 °C in vacuum between heavy passes and never form or heat in air above ~300 °C.
What is the maximum service temperature of T-111-SR?
T-111-SR is rated for continuous use to about 1,400°C (2,552 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between T-111 Annealed and T-111-CW?
Annealed is the default condition — standard stocked condition for sheet, plate, rod and tube — maximum ductility and formability, best for forming and welding. CW: highest room-temperature strength and hardness for springs, fasteners and thin foil; strength is lost on exposure above ~1300 °C. Yield strength is 415 MPa in Annealed versus 830 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)
- ASTM B364 — Tantalum and Tantalum Alloy Castings — ASTM International (2018)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (Refractory Metals) — ASM International (1990)
- NASA technical reports on Ta-8W-2Hf (T-111) for space power systems — NASA (1970)
- Tantalum alloy Ta-8W-2Hf product data — refractory-metal producers (H.C. Starck / Plansee / ) (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.