Refractory Metal C-103 Vacuum Annealed + R512E
Finish state
UNS R04295, R04365 · ASTM B654 · also Niobium-Hafnium
Vacuum Annealed + R512E = vacuum Annealed + R512E silicide coating
The flight condition for radiation-cooled nozzles: coated C-103 resists air oxidation to about 1370 °C for many hours.
Values for the Vacuum Annealed + R512E condition
Other C-103 tempers and conditions
C-103 is listed in 4 conditions; see the grade overview at C-103.
- Vacuum Annealed + R512E
- Vacuum Annealed
- Stress Relieved
- Cold Worked
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Vacuum Annealed + R512EThis page Vacuum Annealed + R512E silicide coating | The flight condition for radiation-cooled nozzles: coated C-103 resists air oxidation to about 1370 °C for many hours. | 265 | 400 | 18 | 170 HB | 5.1 % IACS |
Vacuum AnnealedDefault fully recrystallized (≈1200–1300 °C, vacuum) | Standard stocked condition for sheet/plate/bar that must be deep-drawn, spun or welded into thruster nozzles. | 275 | 415 | 25 | 85 HRB | — |
cold worked then stress-relief annealed (≈1000–1100 °C) | Choose when moderate extra strength and dimensional stability are wanted while keeping useful ductility. | 450 | 550 | 15 | 18 HRC | 5 % IACS |
as-rolled / as-drawn (≈40–60 % reduction, no final anneal) | Highest room-temperature strength; use for springs, fasteners and thin foil where no hot service or forming follows. | 620 | 690 | 8 | 24 HRC | 4.9 % IACS |
What is C-103 Vacuum Annealed + R512E?
C-103 Vacuum Annealed + R512E is C-103 supplied in the Vacuum Annealed + R512E condition — the flight condition for radiation-cooled nozzles: coated C-103 resists air oxidation to about 1370 °C for many hours. C-103 Vacuum Annealed + R512E has a yield strength of 265 MPa (38.4 ksi) and a tensile strength of 400 MPa (58 ksi) — weaker than 64% of refractory metal grades. Elongation at break is 18% and the elastic modulus is 88 GPa (12.8 Msi). C-103 Vacuum Annealed + R512E has a density of 8.85 g/cm³ (0.32 lb/in³), heavier than 56% of refractory metal grades. It melts at 2,350°C (4,262 °F). Vacuum Annealed is the default condition FabDigit quotes; Vacuum Annealed + R512E is available on request or by drawing note.
Advantages
- High service temperature — 1,370°C (2,498 °F), better than 79% of refractory metal grades
Limitations
- Low stiffness — 88 GPa (12.8 Msi), worse than 99% of refractory metal grades
- Difficult to weld — 15/100, worse than 93% of refractory metal grades
- Difficult to machine — 10/100, worse than 89% of refractory metal grades
- Limited formability — 10/100, worse than 86% of refractory metal grades
C-103 Vacuum Annealed + R512E properties
Typical room-temperature values for C-103 Vacuum Annealed + R512E; 22 are specific to this condition. Other listed values are C-103 reference data and may not represent this condition. Bars are the position among refractory metal grades.
Physical3
C-103 Vacuum Annealed + R512E has a density of 8.85 g/cm³ (0.32 lb/in³), heavier than 56% of refractory metal grades. It melts at 2,350°C (4,262 °F).
Mechanical12
C-103 Vacuum Annealed + R512E has a yield strength of 265 MPa (38.4 ksi) and a tensile strength of 400 MPa (58 ksi) — weaker than 64% of refractory metal grades. Elongation at break is 18% and the elastic modulus is 88 GPa (12.8 Msi).
Thermal6
C-103 Vacuum Annealed + R512E is rated for continuous service to 1,370°C (2,498 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), better than 50% of refractory metal grades. Thermal expansion is 7.4 µm/m·K (4.11 µin/in·°F).
Electrical3
C-103 Vacuum Annealed + R512E conducts electricity at 5.1 % IACS, worse than 58% of refractory metal grades.
Chemical & Environmental3
Corrosion resistance is very good (80/100), worse than 54% of refractory metal grades.
Sustainability3
Producing a kilogram of C-103 Vacuum Annealed + R512E takes about 900 MJ of energy and emits 55 kg of CO₂ — less than 59% of refractory metal grades. Typical recycled content is 25%.
Manufacturability8
C-103 Vacuum Annealed + R512E's machinability is not recommended (10/100, worse than 89% of refractory metal grades); weldability poor (15/100); formability not recommended (10/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C-103 Vacuum Annealed + R512E
Is C-103 easy to machine?
Gummy and galling like tantalum — use sharp, high-positive-rake carbide or HSS tools, slow speed, heavy feed, generous chlorinated or water-soluble coolant, and avoid dwelling; grind with SiC and plenty of coolant.
Can C-103 be welded?
Excellent GTAW/EBW/laser weldability, but only in vacuum or high-purity inert chambers/trailing shields — any O, N or H pickup embrittles the weld; clean and pickle before welding, no filler usually needed.
Can C-103 be formed, bent or molded?
Very ductile cold: deep draws, spins and rolls readily with clean tooling and non-chlorinated lubricant; interstage vacuum anneals restore ductility, and hot working is done above ~1100 °C under protection.
What surface finishes work on C-103?
Chemically pickle (HNO₃/HF) then apply R512E silicide or Si-Cr slurry coating for oxidation service; electropolishing and anodic colouring are possible but coating adhesion prep governs flight hardware.
C-103 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 |
|---|---|---|
| Hf | 9 – 11 | 10 |
| Ti | 0.7 – 1.3 | 1 |
| Zrresidual from Hf source | ≤ 0.7 | 0.5 |
| Ta | ≤ 0.5 | — |
| W | ≤ 0.5 | — |
| C | ≤ 0.02 | — |
| O | ≤ 0.03 | — |
| N | ≤ 0.01 | — |
| H | ≤ 0 | — |
| Fe | ≤ 0.01 | — |
| Ni | ≤ 0.01 | — |
| Si | ≤ 0.01 | — |
| Nb | balance | — |
C-103 Vacuum Annealed + R512E — frequently asked
What is C-103 Vacuum Annealed + R512E used for?
C-103 Vacuum Annealed + R512E is typically used for rocket nozzle extensions and inserts, spacecraft thruster combustion chambers, rocket engine thrust chamber liners, hot gas structures and leading edges, radiation shields and heat shields and high-temperature furnace fixtures. In short: aerospace high-temp niobium.
What is the yield strength of C-103 Vacuum Annealed + R512E?
C-103 Vacuum Annealed + R512E has a typical yield strength of 265 MPa (38.4 ksi) and a tensile strength of 400 MPa (58 ksi) — weaker than 64% of refractory metal grades. Strength varies by condition: see the 4 listed tempers.
Is C-103 Vacuum Annealed + R512E easy to machine?
Not especially — machinability is rated not recommended (10/100, worse than 89% of refractory metal grades). Gummy and galling like tantalum — use sharp, high-positive-rake carbide or HSS tools, slow speed, heavy feed, generous chlorinated or water-soluble coolant, and avoid dwelling; grind with SiC and plenty of coolant.
Can C-103 Vacuum Annealed + R512E be welded?
Not readily — weldability is rated poor (15/100). Excellent GTAW/EBW/laser weldability, but only in vacuum or high-purity inert chambers/trailing shields — any O, N or H pickup embrittles the weld; clean and pickle before welding, no filler usually needed.
What surface finishes work on C-103 Vacuum Annealed + R512E?
Chemically pickle (HNO₃/HF) then apply R512E silicide or Si-Cr slurry coating for oxidation service; electropolishing and anodic colouring are possible but coating adhesion prep governs flight hardware.
Can C-103 Vacuum Annealed + R512E be formed, bent or molded?
Very ductile cold: deep draws, spins and rolls readily with clean tooling and non-chlorinated lubricant; interstage vacuum anneals restore ductility, and hot working is done above ~1100 °C under protection.
What is the maximum service temperature of C-103 Vacuum Annealed + R512E?
C-103 Vacuum Annealed + R512E is rated for continuous use to about 1,370°C (2,498 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASTM B654 — Niobium-Hafnium Alloy Foil, Sheet, Strip and Plate — ASTM International (2020)
- ASTM B652 — Niobium-Hafnium Alloy Ingots — ASTM International (2020)
- ASTM B655 — Niobium-Hafnium Alloy Bar, Rod and Wire — ASTM International (2020)
- ASM Handbook Vol. 2 — Properties of Refractory Metals and Alloys — ASM International (1990)
- C-103 (Nb-10Hf-1Ti) alloy datasheet — ATI / Wah Chang refractory metals (2019)
- Refractory-metal nozzle materials and R512E coating performance summaries — NASA technical reports (1972)
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.