Refractory Metal Ta-40Nb
UNS R05240 · ASTM B365
Ta-40Nb is a tantalum-niobium solid-solution alloy with about 40% niobium, covered by UNS R05240 and ASTM B365 and stocked annealed, stress-relieved, cold-worked or as hard-drawn wire.
Reference datasheet — Ta-40Nb 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 Annealed condition
Ta-40Nb tempers and conditions
Ta-40Nb is supplied in 3 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault vacuum recrystallization annealed (sheet, plate, rod, tube) | Standard stocked condition: softest, most ductile, for forming, deep drawing and welded chemical-process fabrication. | 220 | 330 | 27 | 130 HV | — |
Stress relieved | Pick when moderate strength with retained ductility and flatness/dimensional stability is needed (thermowells, tube, machined parts). | 370 | 450 | 15 | 165 HB | 4.2 % IACS |
Cold worked | Highest strength/stiffness-limited sections such as rupture discs, springs, diaphragms and thin strip that will not be recrystallized after forming. | 570 | 620 | 6 | 20 HRC | 4.1 % IACS |
Supply forms, finishes and certifications
Ways Ta-40Nb is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
HD-WIRE | Hard-drawn wire / fine wire | Supply form |
What is Ta-40Nb?
Ta-40Nb is a tantalum-niobium solid-solution alloy with about 40% niobium, covered by UNS R05240 and ASTM B365 and stocked annealed, stress-relieved, cold-worked or as hard-drawn wire. The niobium addition lowers density and cost while retaining most of tantalum's resistance to acids, so it is specified for chemical hardware that does not require full unalloyed tantalum performance. Annealed properties are moderate at 220 MPa yield, 330 MPa tensile and 27% elongation, and service in air is limited to about 300 °C by oxidation. Use unalloyed tantalum (R05400) where corrosion resistance must be maximum. Ta-40Nb has a density of 12.1 g/cm³ (0.437 lb/in³), heavier than 74% of refractory metal grades. It melts at 2,650°C (4,802 °F). Ta-40Nb has a yield strength of 220 MPa (31.9 ksi) and a tensile strength of 330 MPa (47.9 ksi) — weaker than 81% of refractory metal grades. Elongation at break is 27% and the elastic modulus is 138 GPa (20 Msi).
What is Ta-40Nb used for?
- chemical process components
- corrosion-resistant fasteners
- electron tube parts
- capacitor anode alternatives
Advantages
- Readily welded — 85/100, better than 99% of refractory metal grades
- Forms and bends easily — 85/100, better than 87% of refractory metal grades
- Ductile — tolerates forming and impact — 27%, better than 78% of refractory metal grades
Limitations
- Limited service temperature — 300°C (572 °F), worse than 95% of refractory metal grades
- High embodied carbon — 160 kg CO₂/kg, worse than 84% of refractory metal grades
- Low strength — 220 MPa (31.9 ksi), worse than 81% of refractory metal grades
Ta-40Nb properties
Typical room-temperature values for Ta-40Nb-Annealed; bars are the position among refractory metal grades.
Physical3
Ta-40Nb has a density of 12.1 g/cm³ (0.437 lb/in³), heavier than 74% of refractory metal grades. It melts at 2,650°C (4,802 °F).
Mechanical12
Ta-40Nb has a yield strength of 220 MPa (31.9 ksi) and a tensile strength of 330 MPa (47.9 ksi) — weaker than 81% of refractory metal grades. Elongation at break is 27% and the elastic modulus is 138 GPa (20 Msi).
Thermal6
Ta-40Nb is rated for continuous service to 300°C (572 °F). It conducts heat at 32 W/m·K (18.5 BTU/hr·ft·°F), worse than 58% of refractory metal grades. Thermal expansion is 6.8 µm/m·K (3.78 µin/in·°F).
Electrical3
Ta-40Nb conducts electricity at 4.3 % IACS, worse than 62% of refractory metal grades.
Chemical & Environmental2
Corrosion resistance is excellent (90/100), better than 75% of refractory metal grades.
Sustainability3
Producing a kilogram of Ta-40Nb takes about 2,800 MJ of energy and emits 160 kg of CO₂ — more than 84% of refractory metal grades. Typical recycled content is 25%.
Manufacturability8
Ta-40Nb's machinability is poor (22/100, worse than 73% of refractory metal grades); weldability excellent (85/100); 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. Ta-40Nb is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Ta-40Nb
Is Ta-40Nb easy to machine?
Turn/mill slowly with sharp, positive-rake carbide or HSS tooling, heavy flood of chlorinated or sulfurized oil and generous depth of cut — the alloy is gummy, work-hardens and galls, so avoid dwelling and rubbing.
Can Ta-40Nb be welded?
GTAW with high-purity argon/helium and full trailing plus back-purge chambers, EB or laser welding in vacuum; keep O, N, H and carbon pickup near zero as interstitials cause embrittlement, and never weld in air or use flux.
Can Ta-40Nb be formed, bent or molded?
Annealed sheet cold-forms, deep draws, spins and explosively/roll clads readily; use clean lubricants and non-ferrous or coated dies to avoid iron pickup, and vacuum-anneal (~1200–1400 °C) between heavy reductions.
Ta-40Nb 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 |
|---|---|---|
| Nbnominal 40 wt% Nb solid-solution addition | 39 – 41 | 40 |
| Cimpurity max | ≤ 0.01 | 0.01 |
| Oimpurity max | ≤ 0.03 | 0.02 |
| Nimpurity max | ≤ 0.01 | 0.01 |
| Himpurity max | ≤ 0 | 5×10⁻⁴ |
| Feimpurity max | ≤ 0.01 | 0 |
| Tiimpurity max | ≤ 0.01 | 0 |
| Wimpurity max | ≤ 0.05 | 0.01 |
| Moimpurity max | ≤ 0.02 | 0.01 |
| Niimpurity max | ≤ 0.01 | 0 |
| Siimpurity max | ≤ 0.01 | 0 |
| Tabalance, nominally 60 wt% | balance |
What surface finishes work on Ta-40Nb?
Degrease and pickle in HNO3/HF-free acid mixes carefully (HF attacks the metal); mechanical polishing and electropolishing give bright passive surfaces, plating/painting is unnecessary since the native oxide provides the corrosion protection.
Equivalent designations
Standards and trade names that resolve to Refractory Metal Ta-40Nb in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- R05240
- ASTM
- B365
How much does Ta-40Nb cost?
Ta-40Nb is a high-cost refractory metal ($$$$), pricier than about 78% 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.
Ta-40Nb — frequently asked
What is Ta-40Nb used for?
Ta-40Nb is typically used for chemical process components, corrosion-resistant fasteners, electron tube parts and capacitor anode alternatives. In short: lower-cost tantalum substitute; lower density than tantalum; ductile and readily weldable.
What is the yield strength of Ta-40Nb?
Ta-40Nb has a typical yield strength of 220 MPa (31.9 ksi) and a tensile strength of 330 MPa (47.9 ksi) — weaker than 81% of refractory metal grades. Strength varies by condition: see the 3 listed tempers.
Is Ta-40Nb easy to machine?
Not especially — machinability is rated poor (22/100, worse than 73% of refractory metal grades). Turn/mill slowly with sharp, positive-rake carbide or HSS tooling, heavy flood of chlorinated or sulfurized oil and generous depth of cut — the alloy is gummy, work-hardens and galls, so avoid dwelling and rubbing.
Can Ta-40Nb be welded?
Yes — weldability is rated excellent (85/100). GTAW with high-purity argon/helium and full trailing plus back-purge chambers, EB or laser welding in vacuum; keep O, N, H and carbon pickup near zero as interstitials cause embrittlement, and never weld in air or use flux.
What surface finishes work on Ta-40Nb?
Degrease and pickle in HNO3/HF-free acid mixes carefully (HF attacks the metal); mechanical polishing and electropolishing give bright passive surfaces, plating/painting is unnecessary since the native oxide provides the corrosion protection.
Can Ta-40Nb be formed, bent or molded?
Annealed sheet cold-forms, deep draws, spins and explosively/roll clads readily; use clean lubricants and non-ferrous or coated dies to avoid iron pickup, and vacuum-anneal (~1200–1400 °C) between heavy reductions.
What is the maximum service temperature of Ta-40Nb?
Ta-40Nb is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Ta-40Nb Annealed and Ta-40Nb-CW?
Annealed is the default condition — standard stocked condition: softest, most ductile, for forming, deep drawing and welded chemical-process fabrication. CW: highest strength/stiffness-limited sections such as rupture discs, springs, diaphragms and thin strip that will not be recrystallized after forming. Yield strength is 220 MPa in Annealed versus 570 MPa in CW.
How much does Ta-40Nb cost?
Ta-40Nb is a high-cost refractory metal ($$$$), pricier than about 78% 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 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 Ingots — ASTM International (2018)
- ASTM B521 — Tantalum and Tantalum Alloy Seamless and Welded Tubes — ASTM International (2018)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (refractory metals) — ASM International (1990)
- ASM Handbook Vol.3 — Alloy Phase Diagrams (Nb-Ta system) — ASM International (1992)
- Tantalum and tantalum alloy (Ta-2.5W, Ta-40Nb) semi-finished product data — H.C. Starck / Plansee (2022)
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.