Refractory Metal R04261 Annealed
Temper · default condition
UNS R04261 · ASTM B393 Type 4
Standard stocked condition for sheet, plate, bar and tube — maximum ductility for forming, welding and deep drawing.
Values for the Annealed condition
Other R04261 tempers and conditions
R04261 is listed in 4 conditions; see the grade overview at R04261.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefaultThis page vacuum recrystallization annealed (ASTM B393/B392 annealed condition) | Standard stocked condition for sheet, plate, bar and tube — maximum ductility for forming, welding and deep drawing. | 200 | 310 | 25 | 105 HB | 41 W/m·K |
Hot worked / as-forged bar and billet | Mill condition for heavy bar, forgings and machining stock where a final anneal is not required. | 260 | 380 | 20 | 124 HB | 8.4 % IACS |
Stress relieved | Choose when moderate strength must be combined with dimensional stability after cold forming or machining. | 340 | 420 | 15 | 143 HB | 8.4 % IACS |
Cold worked | Highest room-temperature strength and hardness for wire, thin strip and springs, but limited formability and it recrystallizes above ~1100 °C. | 500 | 560 | 8 | 185 HB | — |
What is R04261 Annealed?
R04261 Annealed is R04261 in the Annealed temper — standard stocked condition for sheet, plate, bar and tube — maximum ductility for forming, welding and deep drawing. R04261 Annealed has a yield strength of 200 MPa (29 ksi) and a tensile strength of 310 MPa (45 ksi) — weaker than 87% of refractory metal grades. Elongation at break is 25% and the elastic modulus is 103 GPa (14.9 Msi). R04261 Annealed has a density of 8.57 g/cm³ (0.31 lb/in³), heavier than 51% of refractory metal grades. It melts at 2,410°C (4,370 °F).
Advantages
- Readily welded — 90/100, better than 100% of refractory metal grades
- Forms and bends easily — 92/100, better than 95% of refractory metal grades
Limitations
- Low strength — 200 MPa (29 ksi), worse than 87% of refractory metal grades
R04261 Annealed properties
Typical room-temperature values for R04261 Annealed; 14 are specific to this condition. Other listed values are R04261 reference data and may not represent this condition. Bars are the position among refractory metal grades.
Physical3
R04261 Annealed has a density of 8.57 g/cm³ (0.31 lb/in³), heavier than 51% of refractory metal grades. It melts at 2,410°C (4,370 °F).
Mechanical13
R04261 Annealed has a yield strength of 200 MPa (29 ksi) and a tensile strength of 310 MPa (45 ksi) — weaker than 87% of refractory metal grades. Elongation at break is 25% and the elastic modulus is 103 GPa (14.9 Msi).
Thermal6
R04261 Annealed is rated for continuous service to 1,200°C (2,192 °F). It conducts heat at 41 W/m·K (23.7 BTU/hr·ft·°F), worse than 53% of refractory metal grades. Thermal expansion is 7.1 µm/m·K (3.94 µin/in·°F).
Electrical3
R04261 Annealed conducts electricity at 8.6 % IACS, better than 58% of refractory metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (85/100), better than 52% of refractory metal grades.
Sustainability4
Producing a kilogram of R04261 Annealed takes about 1,100 MJ of energy and emits 65 kg of CO₂ — less than 54% of refractory metal grades. Typical recycled content is 25%.
Manufacturability7
R04261 Annealed's machinability is poor (33/100, better than 71% of refractory metal grades); weldability excellent (90/100); formability excellent (92/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with R04261 Annealed
Is R04261 easy to machine?
Gummy and galling-prone: use sharp high-positive-rake carbide or HSS tools, slow-to-moderate speeds, heavy feeds, chlorinated or flood coolant, and never let the tool dwell; degrease thoroughly before any high-temperature use.
Can R04261 be welded?
Excellent GTAW/EBW/laser weldability but only under high-purity argon trailing shield, glove box or vacuum — any O/N/H pickup above ~500 °C embrittles the weld; no filler needed for thin sections and no post-weld heat treatment other than vacuum stress relief.
Can R04261 be formed, bent or molded?
Very ductile cold: deep draws, spins, bends to tight radii at room temperature with lubricated tooling (avoid iron pickup); anneal 1100–1250 °C in vacuum between heavy reductions.
What surface finishes work on R04261?
Pickle in HNO3/HF mixtures to remove oxide (short exposure — HF attacks Nb), electropolish for high-purity or UHV surfaces, or anodise to a coloured Nb2O5 film; for service in air above ~400 °C an aluminide or silicide coating is mandatory.
R04261 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 |
|---|---|---|
| Zralloying addition; scavenges oxygen | 0.8 – 1.2 | 1 |
| C | ≤ 0.01 | — |
| Omax; looser than reactor grade R04251 | ≤ 0.03 | — |
| N | ≤ 0.01 | — |
| H | ≤ 0 | — |
| Fe | ≤ 0.01 | — |
| Ta | ≤ 0.1 | — |
| W | ≤ 0.05 | — |
| Mo | ≤ 0.02 | — |
| Hf | ≤ 0.02 | — |
| Ti | ≤ 0.03 | — |
| Si | ≤ 0.01 | — |
| Ni | ≤ 0.01 | — |
| Nbbalance; commercial grade per ASTM B391/B392/B393/B394 Type 4 | balance | — |
R04261 Annealed — frequently asked
What is R04261 Annealed used for?
R04261 Annealed is typically used for rocket nozzle liners, high-temperature furnace parts, chemical process equipment and vacuum tube components. In short: commercial Nb-1Zr workhorse; weldable and highly formable; hot service to 1200 °C.
What is the yield strength of R04261 Annealed?
R04261 Annealed has a typical yield strength of 200 MPa (29 ksi) and a tensile strength of 310 MPa (45 ksi) — weaker than 87% of refractory metal grades. Strength varies by condition: see the 4 listed tempers.
Is R04261 Annealed easy to machine?
Not especially — machinability is rated poor (33/100, better than 71% of refractory metal grades). Gummy and galling-prone: use sharp high-positive-rake carbide or HSS tools, slow-to-moderate speeds, heavy feeds, chlorinated or flood coolant, and never let the tool dwell; degrease thoroughly before any high-temperature use.
Can R04261 Annealed be welded?
Yes — weldability is rated excellent (90/100). Excellent GTAW/EBW/laser weldability but only under high-purity argon trailing shield, glove box or vacuum — any O/N/H pickup above ~500 °C embrittles the weld; no filler needed for thin sections and no post-weld heat treatment other than vacuum stress relief.
What surface finishes work on R04261 Annealed?
Pickle in HNO3/HF mixtures to remove oxide (short exposure — HF attacks Nb), electropolish for high-purity or UHV surfaces, or anodise to a coloured Nb2O5 film; for service in air above ~400 °C an aluminide or silicide coating is mandatory.
Can R04261 Annealed be formed, bent or molded?
Very ductile cold: deep draws, spins, bends to tight radii at room temperature with lubricated tooling (avoid iron pickup); anneal 1100–1250 °C in vacuum between heavy reductions.
What is the maximum service temperature of R04261 Annealed?
R04261 Annealed is rated for continuous use to about 1,200°C (2,192 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between R04261 Annealed and R04261-CW?
Annealed is the default condition — standard stocked condition for sheet, plate, bar and tube — maximum ductility for forming, welding and deep drawing. CW: highest room-temperature strength and hardness for wire, thin strip and springs, but limited formability and it recrystallizes above ~1100 °C. Yield strength is 200 MPa in Annealed versus 500 MPa in CW.
Sources
- ASTM B393 — Niobium and Niobium Alloy Strip, Sheet, and Plate (Type 4, R04261) — ASTM International (2018)
- ASTM B392 — Niobium and Niobium Alloy Bar, Rod, and Wire — ASTM International (2020)
- ASTM B391 — Niobium and Niobium Alloy Ingots — ASTM International (2018)
- ASTM B394 — Niobium and Niobium Alloy Seamless and Welded Tubes — ASTM International (2019)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (refractory metals) — ASM International (1990)
- ASM Handbook Vol. 13B — Corrosion: Materials (niobium and tantalum) — ASM International (2005)
- Niobium and Nb-1Zr mill product datasheets — refractory-metal producers (e.g. H.C. Starck / Ningxia Orient Tantalum) (2022)
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.