Cobalt-Chrome Alloy S-816-ST vs S-816-STA
Cobalt-Chrome Alloy · S-816 temper comparison
S-816-ST and S-816-STA are two conditions of the same cobalt-chrome alloy grade, S-816: ST (solution annealed) versus STA (solution treated and aged). The chemistry is identical, so every difference below comes from the condition. S-816-STA is the stronger of the two: yield strength 480 MPa (69.6 ksi) against 345 MPa (50 ksi) for S-816-ST, about 39% more; tensile strength follows at 1,000 MPa (145 ksi) vs 830 MPa (120 ksi). In exchange, S-816-ST is the more ductile: elongation 38% versus 18% for S-816-STA, and S-816-STA is harder (300 HB vs 220 HB). On the shop floor, S-816-ST welds better (fair vs poor).
S-816-STChoose it when the part is bent, formed or impact-loaded, or when it will be welded.
S-816-STAChoose it when strength drives the design.
S-816-ST vs S-816-STA: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all cobalt-chrome alloy grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all cobalt-chrome alloy grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Charpy V-Notch Impact (RT)
Hardness, Brinell
Same in both: Elastic (Young's) Modulus 200 GPa29 Msi · Shear Modulus 77 GPa11.2 Msi · Bulk Modulus 172 GPa24.9 Msi · Poisson's Ratio 0.3 · Shear Strength 640 MPa92.8 ksi · Fatigue Strength (Endurance Limit) 290 MPa42.1 ksi · Hardness, Rockwell C 31 HRC · Hardness, Vickers 315 HV
Physical
Density and transition temperatures.
Same in both: Density 8.68 g/cm³0.31 lb/in³ · Melting Point (Solidus) 1,330°C2,426 °F · Liquidus Temperature 1,400°C2,552 °F
Thermal
How each material carries heat and how hot it can run.
Same in both: Thermal Conductivity 12.5 W/m·K7.2 BTU/hr·ft·°F · Specific Heat Capacity 420 J/kg·K0.1 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 13.9 µm/m·K7.7 µin/in·°F · Latent Heat of Fusion 270 J/g116 BTU/lb · Max Service Temperature (continuous) 870°C1,598 °F · Min Service Temperature -196°C-321 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 1.9 % IACS · Electrical Resistivity 9.1×10⁻⁷ Ω·m35.8 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.15 V · Corrosion Resistance 74 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Weldability
Formability (cold)
Same in both: Machinability Rating (AISI 1212 = 100 %) 10% · Castability 68 / 100 · Brazeability / Solderability 55 / 100 · Polishability 65 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 190 MJ/kg81,685 BTU/lb · Embodied Carbon (primary production) 13 kg CO₂/kg · Embodied Water 340 L/kg40.7 gal/lb · Typical Recycled Content 30%
Strength versus weight
Yield strength against density for every cobalt-chrome alloy grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
S-816-ST vs S-816-STA — frequently asked
Is S-816-STA stronger than S-816-ST?
Yes. S-816-STA has a typical yield strength of 480 MPa (69.6 ksi) against 345 MPa (50 ksi) for S-816-ST — about 39% more. Tensile strength is 1,000 MPa (145 ksi) vs 830 MPa (120 ksi).
Which condition does FabDigit quote by default, ST or STA?
STA is the default S-816 condition in the FabDigit quote flow. The other condition is available on request or by drawing note — specify it in the material field or the part notes and the quote is priced for it.
Which is easier to machine, S-816-ST or S-816-STA?
S-816-ST. Its machinability rates poor (18/100) against not recommended (13/100) for S-816-STA; for welding the order is S-816-ST first (fair, 35/100) then S-816-STA (poor, 25/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in S-816-ST and S-816-STA side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.
Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.