Refractory Metal C-103
UNS R04295, R04365 · ASTM B654 · also Niobium-Hafnium
The most widely used commercial niobium superalloy, combining good high-temperature strength/oxidation resistance with excellent formability; the default choice for rocket engine thrust chambers and hot structures.
Reference datasheet — C-103 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the Vacuum Annealed condition
C-103 tempers and conditions
C-103 is supplied in 4 conditions, soft to hard. Vacuum Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
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?
The most widely used commercial niobium superalloy, combining good high-temperature strength/oxidation resistance with excellent formability; the default choice for rocket engine thrust chambers and hot structures. C-103 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). C-103 has a yield strength of 275 MPa (39.9 ksi) and a tensile strength of 415 MPa (60.2 ksi) — weaker than 64% of refractory metal grades. Elongation at break is 25% and the elastic modulus is 88 GPa (12.8 Msi).
What is C-103 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
- High-temperature furnace fixtures
- Reaction control system valve bodies
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 81% of refractory metal grades
Limitations
- Low stiffness — 88 GPa (12.8 Msi), worse than 99% of refractory metal grades
C-103 properties
Typical room-temperature values for C-103-Vacuum Annealed; bars are the position among refractory metal grades.
Physical3
C-103 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 has a yield strength of 275 MPa (39.9 ksi) and a tensile strength of 415 MPa (60.2 ksi) — weaker than 64% of refractory metal grades. Elongation at break is 25% and the elastic modulus is 88 GPa (12.8 Msi).
Thermal6
C-103 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 conducts electricity at 5.1 % IACS, worse than 58% of refractory metal grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 64% of refractory metal grades.
Sustainability3
Producing a kilogram of C-103 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's machinability is poor (30/100, better than 54% 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.
Strength versus weight in the refractory metal family
Yield strength against density for every refractory metal grade FabDigit runs. C-103 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with C-103
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.
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 |
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.
Equivalent designations
Standards and trade names that resolve to Refractory Metal C-103 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- R04295R04365
- ASTM
- B654
- Trade names
- Niobium-Hafnium
- Also called
- Nb-10Hf-1Ti
How much does C-103 cost?
C-103 is a specialty-cost refractory metal ($$$$$), pricier than about 100% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
C-103 — frequently asked
What is C-103 used for?
C-103 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?
C-103 has a typical yield strength of 275 MPa (39.9 ksi) and a tensile strength of 415 MPa (60.2 ksi) — weaker than 64% of refractory metal grades. Strength varies by condition: see the 4 listed tempers.
Is C-103 easy to machine?
Not especially — machinability is rated poor (30/100, better than 54% 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 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?
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 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?
C-103 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.
How much does C-103 cost?
C-103 is a specialty-cost refractory metal ($$$$$), pricier than about 100% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.