Steel T8 Annealed vs T8 HT 66-67 HRC
Steel · T8 temper comparison
T8 Annealed and T8 HT 66-67 HRC are two conditions of the same steel grade, T8: Annealed versus HT 66-67 HRC (maximum hardness, low-temperature-limit temper). The chemistry is identical, so every difference below comes from the condition. T8 HT 66-67 HRC is the stronger of the two: yield strength 2,000 MPa (290 ksi) against 570 MPa (82.7 ksi) for T8 Annealed, about 3.5 times as much; tensile strength follows at 2,100 MPa (305 ksi) vs 900 MPa (131 ksi). In exchange, T8 Annealed is the more ductile: elongation 15% versus 0% for T8 HT 66-67 HRC, and T8 HT 66-67 HRC is harder (900 HV vs 250 HV). T8 HT 66-67 HRC runs hotter in service (560°C vs 400°C continuous). On the shop floor, T8 Annealed machines more easily (fair vs not recommended) and T8 Annealed welds better (poor vs not recommended).
T8 AnnealedChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
T8 HT 66-67 HRCChoose it when strength drives the design, or when the part sees heat.
T8 Annealed vs T8 HT 66-67 HRC: 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.
Elastic (Young's) Modulus
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Compressive Strength
Charpy V-Notch Impact (RT)
Hardness, Vickers
Same in both: Shear Modulus 85 GPa12.3 Msi · Bulk Modulus 170 GPa24.7 Msi · Poisson's Ratio 0.29 · Hardness, Brinell 240 HB · Hardness, Rockwell B 99 HRB
Physical
Density and transition temperatures.
Same in both: Density 8.6 g/cm³0.31 lb/in³ · Melting Point (Solidus) 1,400°C2,552 °F · Liquidus Temperature 1,460°C2,660 °F
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Max Service Temperature (continuous)
Same in both: Specific Heat Capacity 420 J/kg·K0.1 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 11.2 µm/m·K6.2 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Min Service Temperature -40°C-40 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Same in both: Galvanic Potential (seawater, vs SCE) -0.6 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: Brazeability / Solderability 55 / 100 · Polishability 70 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 60 MJ/kg25,795 BTU/lb · Embodied Carbon (primary production) 4.2 kg CO₂/kg · Embodied Water 90 L/kg10.8 gal/lb · Typical Recycled Content 35%
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.
T8 Annealed vs T8 HT 66-67 HRC — frequently asked
Is T8 HT 66-67 HRC stronger than T8 Annealed?
Yes. T8 HT 66-67 HRC has a typical yield strength of 2,000 MPa (290 ksi) against 570 MPa (82.7 ksi) for T8 Annealed — about 3.5 times as much. Tensile strength is 2,100 MPa (305 ksi) vs 900 MPa (131 ksi).
Which condition does FabDigit quote by default, Annealed or HT 66-67 HRC?
Annealed is the default T8 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, T8 Annealed or T8 HT 66-67 HRC?
T8 Annealed. Its machinability rates fair (35/100) against not recommended (4/100) for T8 HT 66-67 HRC; for welding the order is T8 Annealed first (poor, 15/100) then T8 HT 66-67 HRC (not recommended, 5/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in T8 Annealed and T8 HT 66-67 HRC 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.