Refractory Metal R04210-SR (Stress relieved)
Heat-treated state
UNS R04210 · ASTM B393 Type 2
Pick when dimensional stability and moderate strength are needed without losing all cold-work strengthening.
Values for the SR condition
Other R04210 tempers and conditions
R04210 is listed in 3 conditions; see the grade overview at R04210.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault fully recrystallized (vacuum annealed) | Default stock condition for sheet, plate, rod and tube; maximum ductility for deep drawing, spinning and forming. | 115 | 200 | 40 | 70 HB | — |
SRThis page Stress relieved | Pick when dimensional stability and moderate strength are needed without losing all cold-work strengthening. | 250 | 320 | 20 | 105 HB | 11.5 % IACS |
Cold worked | Highest room-temperature strength for springs, fasteners and thin foil where no recrystallization anneal follows. | 420 | 470 | 8 | 140 HB | — |
What is R04210-SR?
R04210-SR is R04210 heat treated to SR — pick when dimensional stability and moderate strength are needed without losing all cold-work strengthening. R04210-SR has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 320 MPa (46.4 ksi) — weaker than 72% of refractory metal grades. Elongation at break is 20% and the elastic modulus is 103 GPa (14.9 Msi). R04210-SR has a density of 8.57 g/cm³ (0.31 lb/in³), heavier than 51% of refractory metal grades. It melts at 2,468°C (4,474 °F). Annealed is the default condition FabDigit quotes; SR is available on request or by drawing note.
Advantages
- Low embodied carbon — 22 kg CO₂/kg, better than 83% of refractory metal grades
R04210-SR properties
Typical room-temperature values for R04210-SR; 21 are specific to this condition. Other listed values are R04210 reference data and may not represent this condition. Bars are the position among refractory metal grades.
Physical3
R04210-SR has a density of 8.57 g/cm³ (0.31 lb/in³), heavier than 51% of refractory metal grades. It melts at 2,468°C (4,474 °F).
Mechanical13
R04210-SR has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 320 MPa (46.4 ksi) — weaker than 72% of refractory metal grades. Elongation at break is 20% and the elastic modulus is 103 GPa (14.9 Msi).
Thermal6
R04210-SR is rated for continuous service to 400°C (752 °F). It conducts heat at 52 W/m·K (30 BTU/hr·ft·°F), better than 63% of refractory metal grades. Thermal expansion is 7.3 µm/m·K (4.06 µin/in·°F).
Electrical3
R04210-SR conducts electricity at 11.5 % IACS, better than 65% of refractory metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (88/100), better than 64% of refractory metal grades.
Sustainability4
Producing a kilogram of R04210-SR takes about 320 MJ of energy and emits 22 kg of CO₂ — less than 83% of refractory metal grades. Typical recycled content is 25%.
Manufacturability8
R04210-SR's machinability is poor (33/100, better than 71% of refractory metal grades); weldability good (62/100); formability good (65/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with R04210-SR
Is R04210 easy to machine?
Gummy and galling-prone: use sharp, positive-rake carbide or HSS tooling, slow speeds, heavy feeds, flood chlorinated or sulfurized coolant, and avoid dwelling to prevent smearing and work hardening.
Can R04210 be welded?
GTAW/EBW/laser weld readily but must be done in a vacuum chamber or with complete trailing/backing inert gas — any O, N or H pickup above ~250 °C embrittles the weld; use Nb or Nb-1Zr filler.
Can R04210 be formed, bent or molded?
Outstanding cold formability — deep drawing, spinning and >90 % cold rolling reduction are routine with intermediate vacuum anneals at 1100–1300 °C; use non-galling tooling coatings or lubricated interleaf.
What surface finishes work on R04210?
Pickle in HF-HNO3 or buffered chemical polish, electropolish for SRF/UHV surfaces; anodizing gives decorative Nb2O5 interference colours; avoid iron contamination during grinding.
R04210 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 |
|---|---|---|
| Tarelaxed vs reactor grade Type 1 | ≤ 0.3 | 0.1 |
| W | ≤ 0.05 | 0.01 |
| Mo | ≤ 0.02 | 0.01 |
| Zr | ≤ 0.02 | 0.01 |
| Ti | ≤ 0.03 | 0.01 |
| Hf | ≤ 0.02 | 0.01 |
| Fe | ≤ 0.01 | 0 |
| Ni | ≤ 0.01 | 0 |
| Si | ≤ 0.01 | 0 |
| C | ≤ 0.01 | 0 |
| O | ≤ 0.03 | 0.01 |
| N | ≤ 0.01 | 0 |
| H | ≤ 0 | 5×10⁻⁴ |
| Nbbalance; Nb+Ta commonly reported ≥99.8 % | balance | — |
R04210-SR — frequently asked
What is R04210-SR used for?
R04210-SR is typically used for chemical process vessels, superconducting RF components, electronic capacitor anodes and corrosion-resistant liners. In short: most formable refractory metal; baseline commercial niobium; excellent acid corrosion resistance.
What is the yield strength of R04210-SR?
R04210-SR has a typical yield strength of 250 MPa (36.3 ksi) and a tensile strength of 320 MPa (46.4 ksi) — weaker than 72% of refractory metal grades. Strength varies by condition: see the 3 listed tempers.
Is R04210-SR easy to machine?
Not especially — machinability is rated poor (33/100, better than 71% of refractory metal grades). Gummy and galling-prone: use sharp, positive-rake carbide or HSS tooling, slow speeds, heavy feeds, flood chlorinated or sulfurized coolant, and avoid dwelling to prevent smearing and work hardening.
Can R04210-SR be welded?
Yes — weldability is rated good (62/100). GTAW/EBW/laser weld readily but must be done in a vacuum chamber or with complete trailing/backing inert gas — any O, N or H pickup above ~250 °C embrittles the weld; use Nb or Nb-1Zr filler.
What surface finishes work on R04210-SR?
Pickle in HF-HNO3 or buffered chemical polish, electropolish for SRF/UHV surfaces; anodizing gives decorative Nb2O5 interference colours; avoid iron contamination during grinding.
Can R04210-SR be formed, bent or molded?
Outstanding cold formability — deep drawing, spinning and >90 % cold rolling reduction are routine with intermediate vacuum anneals at 1100–1300 °C; use non-galling tooling coatings or lubricated interleaf.
What is the maximum service temperature of R04210-SR?
R04210-SR 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.
What is the difference between R04210 Annealed and R04210-CW?
Annealed is the default condition — default stock condition for sheet, plate, rod and tube; maximum ductility for deep drawing, spinning and forming. CW: highest room-temperature strength for springs, fasteners and thin foil where no recrystallization anneal follows. Yield strength is 115 MPa in Annealed versus 420 MPa in CW.
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)
- 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)
- CRC Handbook of Chemistry and Physics — Physical Properties of the Elements — CRC Press (2023)
- Commercially pure niobium (Nb1 / R04210) mill product datasheet — Refractory-metal producers (ATI / Plansee / ) (2023)
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.