Cobalt-Chrome Alloy S-816-AC vs S-816-CD
Cobalt-Chrome Alloy · S-816 temper comparison
S-816-AC and S-816-CD are two conditions of the same cobalt-chrome alloy grade, S-816: AC (spheroidize annealed) versus CD (cold drawn). The chemistry is identical, so every difference below comes from the condition. S-816-CD is the stronger of the two: yield strength 900 MPa (131 ksi) against 430 MPa (62.4 ksi) for S-816-AC, about 109% more; tensile strength follows at 1,250 MPa (181 ksi) vs 745 MPa (108 ksi). In exchange, S-816-AC is the more ductile: elongation 9% versus 8% for S-816-CD, and S-816-CD is harder (355 HB vs 285 HB). S-816-AC runs hotter in service (870°C vs 700°C continuous).
S-816-ACChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
S-816-CDChoose it when strength drives the design.
S-816-AC vs S-816-CD: 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.
Elastic (Young's) Modulus
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Shear Strength
Fatigue Strength (Endurance Limit)
Hardness, Brinell
Hardness, Rockwell C
Hardness, Vickers
Same in both: Shear Modulus 77 GPa11.2 Msi · Bulk Modulus 172 GPa24.9 Msi · Poisson's Ratio 0.3 · Reduction in Area 10% · Charpy V-Notch Impact (RT) 12 J8.9 ft·lbf
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.
Max Service Temperature (continuous)
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 · 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).
Corrosion Resistance
Same in both: Galvanic Potential (seawater, vs SCE) -0.15 V
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Same in both: 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-AC vs S-816-CD — frequently asked
Is S-816-CD stronger than S-816-AC?
Yes. S-816-CD has a typical yield strength of 900 MPa (131 ksi) against 430 MPa (62.4 ksi) for S-816-AC — about 109% more. Tensile strength is 1,250 MPa (181 ksi) vs 745 MPa (108 ksi).
Which condition does FabDigit quote by default, AC or CD?
STA is the default S-816 condition in the FabDigit quote flow (neither AC nor CD). 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.
When should I choose S-816-AC over S-816-CD?
Pick S-816-AC when the part is bent, formed or impact-loaded, or when the part sees heat. Pick S-816-CD when strength drives the design.
Ready to make it?
Upload a CAD file and FabDigit prices the part in S-816-AC and S-816-CD 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.