Steel T4-ANN vs T4-HT65
Steel · T4 temper comparison
T4-ANN and T4-HT65 are two conditions of the same steel grade, T4: ANN (annealed) versus HT65 (hardened & tempered). The chemistry is identical, so every difference below comes from the condition. Both yield at about 580 MPa — the mechanical properties are the same, and the difference is in how the stock is processed and what it is certified to (annealed versus hardened & tempered). T4-ANN is the more ductile: elongation 12% versus 0% for T4-HT65, and T4-HT65 is harder (855 HV vs 265 HV). T4-HT65 runs hotter in service (620°C vs 500°C continuous) and T4-ANN conducts heat better (24 W/m·K vs 21 W/m·K). On the shop floor, T4-ANN machines more easily (poor vs not recommended).
T4-ANNChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
T4-HT65Choose it when the part sees heat.
T4-ANN vs T4-HT65: 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.
Elongation at Break
Compressive Strength
Charpy V-Notch Impact (RT)
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 215 GPa31.2 Msi · Shear Modulus 84 GPa12.2 Msi · Bulk Modulus 165 GPa23.9 Msi · Poisson's Ratio 0.29 · Tensile Strength (Ultimate) 950 MPa138 ksi · Yield Strength (0.2% offset) 580 MPa84.1 ksi · Reduction in Area 25% · Shear Strength 600 MPa87 ksi · Fatigue Strength (Endurance Limit) 430 MPa62.4 ksi · Hardness, Brinell 255 HB · Hardness, Rockwell B 100 HRB
Physical
Density and transition temperatures.
Same in both: Density 8.75 g/cm³0.32 lb/in³ · Melting Point (Solidus) 1,260°C2,300 °F · Liquidus Temperature 1,430°C2,606 °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 -60°C-76 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 3 % IACS · Electrical Resistivity 5.7×10⁻⁷ Ω·m22.4 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.5 V · Corrosion Resistance 18 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Same in both: Weldability 20 / 100 · Formability (cold) 10 / 100 · Castability 25 / 100 · Brazeability / Solderability 55 / 100 · Polishability 70 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 75 MJ/kg32,244 BTU/lb · Embodied Carbon (primary production) 5.5 kg CO₂/kg · Embodied Water 120 L/kg14.4 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.
T4-ANN vs T4-HT65 — frequently asked
What is the difference between T4-ANN and T4-HT65?
T4-ANN and T4-HT65 are two conditions of the same steel grade, T4: ANN (annealed) versus HT65 (hardened & tempered). The chemistry is identical, so every difference below comes from the condition. Both yield at about 580 MPa — the mechanical properties are the same, and the difference is in how the stock is processed and what it is certified to (annealed versus hardened & tempered).
Which condition does FabDigit quote by default, ANN or HT65?
ANN is the default T4 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, T4-ANN or T4-HT65?
T4-ANN. Its machinability rates poor (30/100) against not recommended (4/100) for T4-HT65.
Ready to make it?
Upload a CAD file and FabDigit prices the part in T4-ANN and T4-HT65 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.