Refractory Metal Pure Nb
UNS R04200 · ASTM B393 Type 1 · also Columbium
Pure Nb is unalloyed high-purity niobium (UNS R04200, ASTM B393 Type 1) with tight O, N, C and H interstitial limits, also stocked in an RRR300 annealed condition for superconducting work.
Reference datasheet — Pure Nb 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
Pure Nb tempers and conditions
Pure Nb is supplied in 5 conditions, soft to hard. Vacuum Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
RRR ≥ 300, high-purity EB-melted and vacuum annealed | Specify for superconducting RF cavities and cryogenic magnets where high residual resistivity ratio, low interstitials and low Ta content control thermal conductivity at 2–4 K. | 70 | 180 | 50 | 48 HB | 12 % IACS |
Vacuum AnnealedDefault fully recrystallized (1100–1300 °C, high vacuum) | Default stocked condition: softest, most ductile and cleanest state for deep drawing, spinning, EB welding and SRF cavity fabrication. | 125 | 220 | 40 | 80 HB | 12 % IACS |
800–950 °C vacuum, partially recovered | Intermediate choice: removes cold-work stresses and hydrogen while keeping most of the cold-worked strength for dimensionally stable machined parts. | 280 | 350 | 22 | 105 HB | 11.5 % IACS |
cold rolled / cold worked, not annealed (~40–60 % reduction) | Pick when higher strength and stiffness-per-thickness are wanted and only mild bending/machining follows; strength is lost on any anneal or hot service above ~800 °C. | 400 | 450 | 10 | 135 HB | 11.5 % IACS |
heavy reduction (>70 %) without anneal | Maximum room-temperature strength for springs, foil, thin wire and stiff diaphragms; very limited remaining ductility. | 570 | 620 | 5 | 10 HRC | 11.5 % IACS |
What is Pure Nb?
Pure Nb is unalloyed high-purity niobium (UNS R04200, ASTM B393 Type 1) with tight O, N, C and H interstitial limits, also stocked in an RRR300 annealed condition for superconducting work. It is chosen for low neutron absorption, good corrosion resistance and outstanding ductility — 125 MPa yield, 220 MPa tensile, 40 % elongation, 80 HB and 53.7 W/m·K annealed — in sheet, plate, rod, wire and tube for deep-drawn and spun parts. In air it needs a coating above about 400 °C, it machines gummy and galls, and it is costly. C-103 is the alternative where hot strength matters. Pure Nb has a density of 8.57 g/cm³ (0.31 lb/in³), heavier than 51% of refractory metal grades. It melts at 2,477°C (4,491 °F). Pure Nb has a yield strength of 125 MPa (18.1 ksi) and a tensile strength of 220 MPa (31.9 ksi) — weaker than 97% of refractory metal grades. Elongation at break is 40% and the elastic modulus is 103 GPa (14.9 Msi).
What is Pure Nb used for?
- Superconducting RF cavities
- Cryogenic vessels and bellows
- Nuclear reactor core components
- Chemical process linings and thermowells
- Sputtering targets
- Anodized jewellery and medical implants
- High-vacuum furnace shielding
Advantages
- Polishes to a fine finish — 85/100, better than 100% of refractory metal grades
- Ductile — tolerates forming and impact — 40%, better than 96% of refractory metal grades
- Forms and bends easily — 92/100, better than 95% of refractory metal grades
- Readily welded — 80/100, better than 92% of refractory metal grades
Limitations
- Low strength — 125 MPa (18.1 ksi), worse than 97% of refractory metal grades
Pure Nb properties
Typical room-temperature values for Pure Nb-Vacuum Annealed; bars are the position among refractory metal grades.
Physical3
Pure Nb has a density of 8.57 g/cm³ (0.31 lb/in³), heavier than 51% of refractory metal grades. It melts at 2,477°C (4,491 °F).
Mechanical13
Pure Nb has a yield strength of 125 MPa (18.1 ksi) and a tensile strength of 220 MPa (31.9 ksi) — weaker than 97% of refractory metal grades. Elongation at break is 40% and the elastic modulus is 103 GPa (14.9 Msi).
Thermal6
Pure Nb is rated for continuous service to 400°C (752 °F). It conducts heat at 53.7 W/m·K (31 BTU/hr·ft·°F), better than 64% of refractory metal grades. Thermal expansion is 7.3 µm/m·K (4.06 µin/in·°F).
Electrical3
Pure Nb conducts electricity at 12 % IACS, better than 67% of refractory metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (90/100), better than 75% of refractory metal grades.
Sustainability4
Producing a kilogram of Pure Nb takes about 500 MJ of energy and emits 32 kg of CO₂ — less than 70% of refractory metal grades. Typical recycled content is 25%.
Manufacturability8
Pure Nb's machinability is poor (28/100, worse than 58% of refractory metal grades); weldability very good (80/100); formability excellent (92/100).
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. Pure Nb is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Pure Nb
Is Pure Nb easy to machine?
Gummy and galling like soft stainless: use sharp positive-rake carbide or HSS, heavy flood of chlorinated/soluble oil, slow speeds (15–30 m/min), generous feed and no dwell to avoid smearing and work-hardened skin.
Can Pure Nb be welded?
EB welding in high vacuum or GTAW inside an inert glovebox/trailing shield; any air, oxygen or nitrogen pickup embrittles the weld, and cleanliness plus post-weld vacuum degassing are essential.
Can Pure Nb be formed, bent or molded?
Outstanding cold formability — deep drawing, spinning and 180° bends in the annealed state; interstage vacuum anneals at 1100–1200 °C restore ductility, and tooling must be non-galling (bronze/coated dies with dry-film lube).
Pure Nb 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 |
|---|---|---|
| TaRRR/SRF grades typically ≤ 0.05 % | ≤ 0.1 | 0.05 |
| W | ≤ 0.05 | |
| Mo | ≤ 0.02 | |
| Zr | ≤ 0.02 | |
| Ti | ≤ 0.02 | |
| Hf | ≤ 0.02 | |
| Fe | ≤ 0.01 | |
| Ni | ≤ 0.01 | |
| Si | ≤ 0.01 | |
| Ointerstitial; controls hardness/RRR | ≤ 0.03 | 0.01 |
| N | ≤ 0.01 | 0 |
| C | ≤ 0.01 | 0 |
| Hhydrogen embrittlement limit | ≤ 0 | |
| Nbcommercially pure / reactor grade R04200 | ≥ 99.8 (balance) |
What surface finishes work on Pure Nb?
Pickle in HNO3/HF mixtures, then buff-and-electropolish (HF-H2SO4) for SRF or vacuum surfaces; anodizing gives decorative interference colours, and a thin Nb2O5 or silicide/aluminide coating is required for any use in air above ~400 °C.
Equivalent designations
Standards and trade names that resolve to Refractory Metal Pure Nb in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- R04200
- ASTM
- B393 Type 1
- Trade names
- Columbium
How much does Pure Nb cost?
Pure Nb 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.
Pure Nb — frequently asked
What is Pure Nb used for?
Pure Nb is typically used for superconducting RF cavities, cryogenic vessels and bellows, nuclear reactor core components, chemical process linings and thermowells, sputtering targets and anodized jewellery and medical implants. In short: superconductor-grade niobium.
What is the yield strength of Pure Nb?
Pure Nb has a typical yield strength of 125 MPa (18.1 ksi) and a tensile strength of 220 MPa (31.9 ksi) — weaker than 97% of refractory metal grades. Strength varies by condition: see the 5 listed tempers.
Is Pure Nb easy to machine?
Not especially — machinability is rated poor (28/100, worse than 58% of refractory metal grades). Gummy and galling like soft stainless: use sharp positive-rake carbide or HSS, heavy flood of chlorinated/soluble oil, slow speeds (15–30 m/min), generous feed and no dwell to avoid smearing and work-hardened skin.
Can Pure Nb be welded?
Yes — weldability is rated very good (80/100). EB welding in high vacuum or GTAW inside an inert glovebox/trailing shield; any air, oxygen or nitrogen pickup embrittles the weld, and cleanliness plus post-weld vacuum degassing are essential.
What surface finishes work on Pure Nb?
Pickle in HNO3/HF mixtures, then buff-and-electropolish (HF-H2SO4) for SRF or vacuum surfaces; anodizing gives decorative interference colours, and a thin Nb2O5 or silicide/aluminide coating is required for any use in air above ~400 °C.
Can Pure Nb be formed, bent or molded?
Outstanding cold formability — deep drawing, spinning and 180° bends in the annealed state; interstage vacuum anneals at 1100–1200 °C restore ductility, and tooling must be non-galling (bronze/coated dies with dry-film lube).
What is the maximum service temperature of Pure Nb?
Pure Nb is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Pure Nb cost?
Pure Nb 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 B393 — Niobium and Niobium Alloy Strip, Sheet and Plate — ASTM International (2020)
- ASTM B392 — Niobium and Niobium Alloy Bar, Rod and Wire — ASTM International (2020)
- ASM Handbook Vol. 2 — Properties of Refractory Metals and Alloys — ASM International (1990)
- ASM Handbook Vol. 13B — Corrosion: Materials (Niobium and Tantalum) — ASM International (2005)
- CRC Handbook of Chemistry and Physics — physical constants of niobium — CRC Press (2022)
- Niobium sheet, rod and RRR SRF-grade material data — ATI / Plansee / (OTIC) (2023)
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.