Refractory Metal FS-85
UNS R04366
FS-85 is a refractory tantalum-niobium alloy containing tungsten and zirconium (UNS R04366), balancing high-temperature strength with ductility and fabricability.
Reference datasheet — FS-85 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 REX condition
FS-85 tempers and conditions
FS-85 is supplied in 6 conditions, soft to hard. REX is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As cast | Ingot condition supplied for remelt or subsequent conversion — coarse grain, lower strength, not used for finished structural parts. | 400 | 520 | 25 | 190 HB | 3.5 % IACS |
As-welded deposit | Property basis for joint design; FS-85 welds stay ductile if oxygen/nitrogen pickup is controlled in a high-purity chamber. | 450 | 560 | 15 | 214 HB | 3.4 % IACS |
REXDefault Recrystallized Annealed | Standard stocked condition for sheet, plate and bar — best ductility, formability and weldability, used for creep-limited high-temperature service. | 480 | 585 | 22 | 18 HRC | 3.4 % IACS |
Hot Worked / As-Forged bar and plate | Mill condition for heavy bar, billet and forgings before final vacuum anneal; strength between annealed and cold-worked. | 550 | 660 | 19 | 21 HRC | 3.3 % IACS |
Stress relieved | Pick when moderately higher room-temperature strength is wanted while removing cold-work residual stress before welding or machining. | 630 | 720 | 15 | 24 HRC | 3.4 % IACS |
Cold worked | Highest room-temperature strength for foil, thin sheet and wire, but limited ductility and it recrystallizes above ~1250 °C. | 830 | 900 | 6 | 32 HRC | 3.3 % IACS |
What is FS-85?
FS-85 is a refractory tantalum-niobium alloy containing tungsten and zirconium (UNS R04366), balancing high-temperature strength with ductility and fabricability. It is supplied recrystallized, stress-relieved, cold-worked, hot-worked, cast or as-welded and is used for thermal-structural aerospace sheet and forgings, with 480 MPa yield, 585 MPa tensile, 22% elongation and service to 1500 °C in vacuum or inert atmosphere. It has no inherent oxidation resistance in air, so an R512E-type silicide coating is required above roughly 450 °C, and machinability is poor (score 25). T-111 is the alternative where higher temperature capability is needed. FS-85 has a density of 10.6 g/cm³ (0.383 lb/in³), heavier than 71% of refractory metal grades. It melts at 2,590°C (4,694 °F). FS-85 has a yield strength of 480 MPa (69.6 ksi) and a tensile strength of 585 MPa (84.8 ksi) — stronger than 72% of refractory metal grades. Elongation at break is 22% and the elastic modulus is 138 GPa (20 Msi).
What is FS-85 used for?
- rocket thruster components
- high-temperature aerospace sheet parts
- heat shields
- nuclear propulsion hardware
Advantages
- Tough — resists crack growth — 80 MPa·√m (72.8 ksi·√in), better than 91% of refractory metal grades
- High service temperature — 1,500°C (2,732 °F), better than 86% of refractory metal grades
- Forms and bends easily — 70/100, better than 75% of refractory metal grades
FS-85 properties
Typical room-temperature values for FS-85-REX; bars are the position among refractory metal grades.
Physical3
FS-85 has a density of 10.6 g/cm³ (0.383 lb/in³), heavier than 71% of refractory metal grades. It melts at 2,590°C (4,694 °F).
Mechanical17
FS-85 has a yield strength of 480 MPa (69.6 ksi) and a tensile strength of 585 MPa (84.8 ksi) — stronger than 72% of refractory metal grades. Elongation at break is 22% and the elastic modulus is 138 GPa (20 Msi).
Thermal5
FS-85 is rated for continuous service to 1,500°C (2,732 °F). It conducts heat at 40 W/m·K (23.1 BTU/hr·ft·°F), worse than 55% of refractory metal grades. Thermal expansion is 7 µm/m·K (3.89 µin/in·°F).
Electrical3
FS-85 conducts electricity at 3.4 % IACS, worse than 72% of refractory metal grades.
Chemical & Environmental3
Corrosion resistance is very good (72/100), worse than 58% of refractory metal grades.
Sustainability3
Producing a kilogram of FS-85 takes about 900 MJ of energy and emits 60 kg of CO₂ — less than 59% of refractory metal grades. Typical recycled content is 25%.
Manufacturability7
FS-85's machinability is poor (25/100, worse than 65% of refractory metal grades); weldability very good (70/100); formability very good (70/100).
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. FS-85 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with FS-85
Is FS-85 easy to machine?
Machine like a gummy refractory metal: sharp uncoated carbide, positive rake, slow speed, heavy flood coolant, avoid dwell to prevent galling and work hardening.
Can FS-85 be welded?
Electron-beam or GTAW inside a high-purity argon chamber or vacuum; any oxygen/nitrogen pickup embrittles the weld, so joints must be spotlessly clean and back-shielded.
Can FS-85 be formed, bent or molded?
Cold rollable and formable at room temperature with generous bend radii and intermediate vacuum anneals; heavy sections are forged/extruded hot at 1200–1400 °C with cladding or glass lubricant.
FS-85 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 |
|---|---|---|
| Taprimary solid-solution strengthener | 26 – 29 | 28 |
| W | 10 – 11.5 | 10.5 |
| Zrgetters O/C, forms fine ZrO2/ZrC dispersion | 0.7 – 1.3 | 1 |
| Cimpurity limit | ≤ 0.03 | 0.01 |
| Oimpurity limit | ≤ 0.02 | 0.01 |
| Nimpurity limit | ≤ 0.01 | 0 |
| Himpurity limit | ≤ 0 | 5×10⁻⁴ |
| Feimpurity limit | ≤ 0.01 | |
| Nbbalance, ~60 wt % | balance |
What surface finishes work on FS-85?
Chemical etch (HF-HNO3) or electropolish to remove smeared metal; for use in air above ~450 °C apply an R512E-type silicide diffusion coating.
Equivalent designations
Standards and trade names that resolve to Refractory Metal FS-85 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- R04366
- Also called
- Ta-10W-3Nb-1ZrNb-27Ta-10W-1Zr
How much does FS-85 cost?
FS-85 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.
FS-85 — frequently asked
What is FS-85 used for?
FS-85 is typically used for rocket thruster components, high-temperature aerospace sheet parts, heat shields and nuclear propulsion hardware. In short: fabricable refractory sheet alloy; 1500 °C service capability; silicide coating required.
What is the yield strength of FS-85?
FS-85 has a typical yield strength of 480 MPa (69.6 ksi) and a tensile strength of 585 MPa (84.8 ksi) — stronger than 72% of refractory metal grades. Strength varies by condition: see the 6 listed tempers.
Is FS-85 easy to machine?
Not especially — machinability is rated poor (25/100, worse than 65% of refractory metal grades). Machine like a gummy refractory metal: sharp uncoated carbide, positive rake, slow speed, heavy flood coolant, avoid dwell to prevent galling and work hardening.
Can FS-85 be welded?
Yes — weldability is rated very good (70/100). Electron-beam or GTAW inside a high-purity argon chamber or vacuum; any oxygen/nitrogen pickup embrittles the weld, so joints must be spotlessly clean and back-shielded.
What surface finishes work on FS-85?
Chemical etch (HF-HNO3) or electropolish to remove smeared metal; for use in air above ~450 °C apply an R512E-type silicide diffusion coating.
Can FS-85 be formed, bent or molded?
Cold rollable and formable at room temperature with generous bend radii and intermediate vacuum anneals; heavy sections are forged/extruded hot at 1200–1400 °C with cladding or glass lubricant.
What is the maximum service temperature of FS-85?
FS-85 is rated for continuous use to about 1,500°C (2,732 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between FS-85-REX and FS-85-CW?
REX is the default condition — standard stocked condition for sheet, plate and bar — best ductility, formability and weldability, used for creep-limited high-temperature service. CW: highest room-temperature strength for foil, thin sheet and wire, but limited ductility and it recrystallizes above ~1250 °C. Yield strength is 480 MPa in REX versus 830 MPa in CW.
How much does FS-85 cost?
FS-85 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
- ASM Handbook, Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (refractory metals section) — ASM International (1990)
- Refractory Metals and Alloys — property compilations for Nb-base alloys (C-103, Cb-752, FS-85) — Plenum / TMS literature (1988)
- Niobium and tantalum alloy mill product data (FS-85, C-103) — ATI Wah Chang (2015)
- ASTM B654 / B655 — Niobium-alloy strip, sheet, plate and bar (related product specifications) — ASTM International (2020)
- NASA technical reports on FS-85 for space power and thermal-structural applications — NASA NTRS (2010)
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.