Steel 8660 Annealed vs 8660-HR
Steel · 8660 temper comparison
8660 Annealed and 8660-HR are two conditions of the same steel grade, 8660: Annealed versus HR (hot rolled). The chemistry is identical, so every difference below comes from the condition. 8660-HR is the stronger of the two: yield strength 585 MPa (84.8 ksi) against 460 MPa (66.7 ksi) for 8660 Annealed, about 27% more; tensile strength follows at 965 MPa (140 ksi) vs 800 MPa (116 ksi). In exchange, 8660 Annealed is the more ductile: elongation 20% versus 13% for 8660-HR, and 8660-HR is harder (285 HB vs 230 HB).
8660 AnnealedChoose it when the part is bent, formed or impact-loaded.
8660-HRChoose it when strength drives the design.
8660 Annealed vs 8660-HR: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all steel 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 steel 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
Fatigue Strength (Endurance Limit)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Same in both: Elastic (Young's) Modulus 205 GPa29.7 Msi · Shear Modulus 80 GPa11.6 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Compressive Strength 585 MPa84.8 ksi · Shear Strength 620 MPa89.9 ksi · Fracture Toughness (K_IC) 55 MPa·√m50.1 ksi·√in · Hardness, Rockwell C 29 HRC · Hardness, Vickers 300 HV
Physical
Density and transition temperatures.
Same in both: Density 7.85 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,415°C2,579 °F · Liquidus Temperature 1,480°C2,696 °F
Thermal
How each material carries heat and how hot it can run.
Same in both: Thermal Conductivity 44 W/m·K25.4 BTU/hr·ft·°F · Specific Heat Capacity 475 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 11.7 µm/m·K6.5 µin/in·°F · Latent Heat of Fusion 270 J/g116 BTU/lb · Max Service Temperature (continuous) 400°C752 °F · Min Service Temperature -30°C-22 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 7.2 % IACS · Electrical Resistivity 2.4×10⁻⁷ Ω·m9.45 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.6 V · Corrosion Resistance 11 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Formability (cold)
Same in both: Weldability 20 / 100 · Polishability 65 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 30 MJ/kg12,898 BTU/lb · Embodied Carbon (primary production) 2.2 kg CO₂/kg · Embodied Water 45 L/kg5.4 gal/lb · Typical Recycled Content 30%
Strength versus weight
Yield strength against density for every steel grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
8660 Annealed vs 8660-HR — frequently asked
Is 8660-HR stronger than 8660 Annealed?
Yes. 8660-HR has a typical yield strength of 585 MPa (84.8 ksi) against 460 MPa (66.7 ksi) for 8660 Annealed — about 27% more. Tensile strength is 965 MPa (140 ksi) vs 800 MPa (116 ksi).
Which condition does FabDigit quote by default, Annealed or HR?
HR is the default 8660 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, 8660 Annealed or 8660-HR?
8660 Annealed, by a small margin. Both rate fair for machinability — 48/100 against 40/100 for 8660-HR.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 8660 Annealed and 8660-HR 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.