Refractory Metal C-103 · heat-treated state · default condition
Refractory Metal C-103 Vacuum Annealed
Properties of the Vacuum Annealed condition, compared with the other C-103 tempers.
Standard stocked condition for sheet/plate/bar that must be deep-drawn, spun or welded into thruster nozzles.
What is C-103 Vacuum Annealed?
C-103 Vacuum Annealed is C-103 heat treated to Vacuum Annealed — standard stocked condition for sheet/plate/bar that must be deep-drawn, spun or welded into thruster nozzles. C-103 Vacuum Annealed has a yield strength of 275 MPa (39.9 ksi) and a tensile strength of 415 MPa (60.2 ksi) — weaker than 65% of refractory metal grades. Elongation at break is 25% and the elastic modulus is 88 GPa (12.8 Msi). C-103 Vacuum Annealed 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).
Advantages
- Readily welded — 80/100, better than 92% of refractory metal grades
- Forms and bends easily — 85/100, better than 87% of refractory metal grades
- High service temperature — 1,400°C (2,552 °F), better than 79% of refractory metal grades
Limitations
- Low stiffness — 88 GPa (12.8 Msi), worse than 99% of refractory metal grades
C-103 Vacuum Annealed properties
Typical room-temperature values for C-103 Vacuum Annealed — 10 properties are specific to this condition; the rest are grade-level values shared by every C-103 temper. Each bar shows where the value sits among the refractory metal grades in FabDigit's library — further right is higher.
Physical3
C-103 Vacuum Annealed 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 has a yield strength of 275 MPa (39.9 ksi) and a tensile strength of 415 MPa (60.2 ksi) — weaker than 65% of refractory metal grades. Elongation at break is 25% and the elastic modulus is 88 GPa (12.8 Msi).
Thermal6
C-103 Vacuum Annealed is rated for continuous service to 1,400°C (2,552 °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 conducts electricity at 5.1 % IACS, worse than 59% of refractory metal grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 66% of refractory metal grades.
Sustainability3
Producing a kilogram of C-103 Vacuum Annealed 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's machinability is poor (30/100, better than 55% of refractory metal grades); weldability very good (80/100); formability excellent (85/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other C-103 tempers and conditions
C-103 is also supplied in 3 other conditions. The full side-by-side table is on the C-103 overview.
- Vacuum AnnealedDefaultStandard stocked condition for sheet/plate/bar that must be deep-drawn, spun or welded into thruster nozzles.275 MPa yield · 85 HRB
- Cold WorkedHighest room-temperature strength; use for springs, fasteners and thin foil where no hot service or forming follows.620 MPa yield · 100 HRB
- Stress RelievedChoose when moderate extra strength and dimensional stability are wanted while keeping useful ductility.450 MPa yield · 96 HRB
Working with C-103 Vacuum Annealed
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 — frequently asked
What is C-103 Vacuum Annealed used for?
C-103 Vacuum Annealed 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?
C-103 Vacuum Annealed has a typical yield strength of 275 MPa (39.9 ksi) and a tensile strength of 415 MPa (60.2 ksi) — weaker than 65% of refractory metal grades. Strength varies by condition: see the 4 listed tempers.
Is C-103 Vacuum Annealed easy to machine?
Not especially — machinability is rated poor (30/100, better than 55% 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 be welded?
Yes — weldability is rated very good (80/100). 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?
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 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?
C-103 Vacuum Annealed 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.
Can FabDigit make parts in C-103 Vacuum Annealed?
Yes — C-103 Vacuum Annealed is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
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.