Steel M7-ANN vs M7 HT64-66
Steel · M7 temper comparison
M7-ANN and M7 HT64-66 are two conditions of the same steel grade, M7: ANN (annealed) versus HT64-66 (hardened & tempered, 64–66 HRC). The chemistry is identical, so every difference below comes from the condition. M7 HT64-66 is the stronger of the two: tensile strength 2,400 MPa (348 ksi) against 830 MPa (120 ksi) for M7-ANN, about 189% more. In exchange, M7-ANN is the more ductile: elongation 18% versus 0.5% for M7 HT64-66, and M7 HT64-66 is harder (860 HV vs 248 HV). M7 HT64-66 runs hotter in service (560°C vs 500°C continuous). On the shop floor, M7-ANN machines more easily (poor vs not recommended).
M7-ANNChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
M7 HT64-66Choose it when strength drives the design, or when the part sees heat.
M7-ANN vs M7 HT64-66: 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)
Elongation at Break
Compressive Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Vickers
Same in both: Shear Modulus 80 GPa11.6 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Yield Strength (0.2% offset) 520 MPa75.4 ksi · Reduction in Area 30% · Shear Strength 520 MPa75.4 ksi · Hardness, Brinell 235 HB · Hardness, Rockwell B 99 HRB
Physical
Density and transition temperatures.
Same in both: Density 7.95 g/cm³0.29 lb/in³ · Melting Point (Solidus) 1,250°C2,282 °F · Liquidus Temperature 1,430°C2,606 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 24 W/m·K13.9 BTU/hr·ft·°F · Specific Heat Capacity 420 J/kg·K0.1 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 10.9 µm/m·K6.1 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 3.1 % IACS · Electrical Resistivity 5.5×10⁻⁷ Ω·m21.7 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.55 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 12 / 100 · Formability (cold) 15 / 100 · Castability 25 / 100 · Brazeability / Solderability 45 / 100 · Polishability 65 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 44 MJ/kg18,917 BTU/lb · Embodied Carbon (primary production) 3.3 kg CO₂/kg · Embodied Water 70 L/kg8.4 gal/lb · Typical Recycled Content 40%
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.
M7-ANN vs M7 HT64-66 — frequently asked
Is M7 HT64-66 stronger than M7-ANN?
Yes. M7 HT64-66 has a typical tensile strength of 2,400 MPa (348 ksi) against 830 MPa (120 ksi) for M7-ANN — about 189% more.
Which condition does FabDigit quote by default, ANN or HT64-66?
ANN is the default M7 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, M7-ANN or M7 HT64-66?
M7-ANN. Its machinability rates poor (32/100) against not recommended (5/100) for M7 HT64-66.
Ready to make it?
Upload a CAD file and FabDigit prices the part in M7-ANN and M7 HT64-66 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.