Cobalt-Chrome Alloy S-816
UNS R30816 · also Haynes S-816
S-816 is a historic cobalt-chromium-nickel-tungsten superalloy (UNS R30816, formerly Grade 671) strengthened by a high-carbon carbide network plus solid-solution tungsten and molybdenum.
Reference datasheet — S-816 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 STA condition
S-816 tempers and conditions
S-816 is supplied in 6 conditions, soft to hard. STA 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 |
|---|---|---|---|---|---|---|
Solution annealed | Softest supplied condition — used before final forming/machining, or where maximum ductility and homogeneity are needed prior to aging. | 345 | 830 | 38 | 220 HB | — |
Hot Rolled + Annealed | Mill condition for bar/billet stock destined for forging or re-heat-treatment; moderate strength, good ductility. | 400 | 870 | 30 | 24 HRC | 1.9 % IACS |
Spheroidize annealed | Investment-cast blades, vanes and nozzle parts used directly in the as-cast condition; coarse carbide network, lower ductility. | 430 | 745 | 9 | 29 HRC | 1.9 % IACS |
Cast + Heat Treated | Castings homogenised and aged to refine carbide distribution — better creep-rupture consistency than as-cast. | 460 | 800 | 11 | 30 HRC | 1.9 % IACS |
STADefault Solution treated and aged | Standard service condition for wrought bar/forgings: carbide precipitation gives peak elevated-temperature strength and creep life. | 480 | 1,000 | 18 | 31 HRC | — |
Cold drawn | Cold-drawn small bar and wire where higher room-temperature strength and tight tolerance matter more than ductility. | 900 | 1,250 | 8 | 38 HRC | 1.9 % IACS |
Supply forms, finishes and certifications
Ways S-816 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
Sheet-Ann | Sheet, Annealed | Supply form |
What is S-816?
S-816 is a historic cobalt-chromium-nickel-tungsten superalloy (UNS R30816, formerly Grade 671) strengthened by a high-carbon carbide network plus solid-solution tungsten and molybdenum. Engineers specify it for hot-section strength — 480 MPa yield, 1000 MPa tensile, 18% elongation, 300 HB (31 HRC) and service to 870 °C — in forged and hot-rolled bar, annealed sheet and investment castings. Its limits are severe: machinability rates 13, formability 15, and the high carbon content makes it crack-sensitive in welding (weldability 25). L605 or Haynes 188 are the usual modern substitutes when supply or fabrication cost matters. S-816 has a density of 8.68 g/cm³ (0.314 lb/in³), heavier than 79% of cobalt-chrome alloy grades. It melts at 1,330°C (2,426 °F). S-816 has a yield strength of 480 MPa (69.6 ksi) and a tensile strength of 1,000 MPa (145 ksi) — weaker than 77% of cobalt-chrome alloy grades. Elongation at break is 18% and the elastic modulus is 200 GPa (29 Msi).
What is S-816 used for?
- turbine blades and vanes
- afterburner components
- high-temp fasteners
Limitations
- Hard to polish — 65/100, worse than 96% of cobalt-chrome alloy grades
- Low strength — 480 MPa (69.6 ksi), worse than 77% of cobalt-chrome alloy grades
S-816 properties
Typical room-temperature values for S-816-STA; bars are the position among cobalt-chrome alloy grades.
Physical3
S-816 has a density of 8.68 g/cm³ (0.314 lb/in³), heavier than 79% of cobalt-chrome alloy grades. It melts at 1,330°C (2,426 °F).
Mechanical14
S-816 has a yield strength of 480 MPa (69.6 ksi) and a tensile strength of 1,000 MPa (145 ksi) — weaker than 77% of cobalt-chrome alloy grades. Elongation at break is 18% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
S-816 is rated for continuous service to 870°C (1,598 °F). It conducts heat at 12.5 W/m·K (7.22 BTU/hr·ft·°F), worse than 77% of cobalt-chrome alloy grades. Thermal expansion is 13.9 µm/m·K (7.72 µin/in·°F).
Electrical3
S-816 conducts electricity at 1.9 % IACS, worse than 52% of cobalt-chrome alloy grades.
Chemical & Environmental3
Corrosion resistance is very good (74/100), worse than 54% of cobalt-chrome alloy grades.
Sustainability4
Producing a kilogram of S-816 takes about 190 MJ of energy and emits 13 kg of CO₂ — more than 70% of cobalt-chrome alloy grades. Typical recycled content is 30%.
Manufacturability7
S-816's machinability is not recommended (13/100, better than 68% of cobalt-chrome alloy grades); weldability poor (25/100); formability poor (15/100).
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 cobalt-chrome alloy family
Yield strength against density for every cobalt-chrome alloy grade FabDigit runs. S-816 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with S-816
Is S-816 easy to machine?
Very difficult — rigid setups, positive-rake carbide or ceramic tooling, low speed (10–20 m/min carbide), heavy constant feed and flood coolant to avoid work hardening and glazing; grinding preferred for finish.
Can S-816 be welded?
GTAW with matched or Co-base filler in the solution-treated condition only; high carbon makes it crack-sensitive, so preheat is unnecessary but low heat input, minimal restraint and a full post-weld solution+age are required.
Can S-816 be formed, bent or molded?
Hot work 1100–1200 °C with frequent reheats; cold forming limited to gentle bends on annealed sheet — plan interstage anneals, and investment casting is the usual route for complex airfoils.
S-816 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 |
|---|---|---|
| Chigh carbon — carbide strengthening | 0.32 – 0.42 | 0.38 |
| Mn | 1 – 2 | 1.2 |
| Si | ≤ 1 | 0.4 |
| Cr | 19 – 21 | 20 |
| NiFCC matrix stabiliser | 19 – 21 | 20 |
| Mo | 3.5 – 4.5 | 4 |
| W | 3.5 – 4.5 | 4 |
| NbCb; may include incidental Ta | 3.5 – 4.5 | 4 |
| Fe | ≤ 5 | 4 |
| S | ≤ 0.03 | |
| P | ≤ 0.04 | |
| Cobalance, ~42 % | balance |
What surface finishes work on S-816?
Not anodizable; use abrasive blast plus pickling for scale removal, and aluminide/MCrAlY diffusion coatings for hot-gas surfaces; polishes to a bright finish though carbides can pull out.
Equivalent designations
Standards and trade names that resolve to Cobalt-Chrome Alloy S-816 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- R30816
- Trade names
- Haynes S-816
- Also called
- Grade 671
How much does S-816 cost?
S-816 is a high-cost cobalt-chrome alloy ($$$$), 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.
S-816 — frequently asked
What is S-816 used for?
S-816 is typically used for turbine blades and vanes, afterburner components and high-temp fasteners. In short: legacy cobalt turbine alloy; carbide-strengthened to 870 °C; very difficult to machine.
What is the yield strength of S-816?
S-816 has a typical yield strength of 480 MPa (69.6 ksi) and a tensile strength of 1,000 MPa (145 ksi) — weaker than 77% of cobalt-chrome alloy grades. Strength varies by condition: see the 6 listed tempers.
Is S-816 easy to machine?
Not especially — machinability is rated not recommended (13/100, better than 68% of cobalt-chrome alloy grades). Very difficult — rigid setups, positive-rake carbide or ceramic tooling, low speed (10–20 m/min carbide), heavy constant feed and flood coolant to avoid work hardening and glazing; grinding preferred for finish.
Can S-816 be welded?
Not readily — weldability is rated poor (25/100). GTAW with matched or Co-base filler in the solution-treated condition only; high carbon makes it crack-sensitive, so preheat is unnecessary but low heat input, minimal restraint and a full post-weld solution+age are required.
What surface finishes work on S-816?
Not anodizable; use abrasive blast plus pickling for scale removal, and aluminide/MCrAlY diffusion coatings for hot-gas surfaces; polishes to a bright finish though carbides can pull out.
Can S-816 be formed, bent or molded?
Hot work 1100–1200 °C with frequent reheats; cold forming limited to gentle bends on annealed sheet — plan interstage anneals, and investment casting is the usual route for complex airfoils.
What is the maximum service temperature of S-816?
S-816 is rated for continuous use to about 870°C (1,598 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between S-816-STA and S-816-CD?
STA is the default condition — standard service condition for wrought bar/forgings: carbide precipitation gives peak elevated-temperature strength and creep life. CD: cold-drawn small bar and wire where higher room-temperature strength and tight tolerance matter more than ductility. Yield strength is 480 MPa in STA versus 900 MPa in CD.
How much does S-816 cost?
S-816 is a high-cost cobalt-chrome alloy ($$$$), 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
- Superalloys Source Book / ASM Handbook Vol.1 — Cobalt-Base Heat-Resistant Alloys — ASM International (1990)
- Aerospace Structural Metals Handbook — S-816 (Grade 671) — CINDAS/Purdue (1998)
- SAE AMS 5765 — Cobalt Alloy Bars, Forgings and Rings 20Cr-20Ni-4W-4Mo-4Cb — SAE International (2012)
- SAE/ASTM UNS R30816 alloy designation — SAE/ASTM (2018)
- Machining Data Handbook — heat-resistant cobalt alloys — Metcut Research (1980)
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.