Steel M62-A vs M62 QT64-66
Steel · M62 temper comparison
M62-A and M62 QT64-66 are two conditions of the same steel grade, M62: A (solution annealed) versus QT64-66 (Q&T 64–66 HRC). The chemistry is identical, so every difference below comes from the condition. M62 QT64-66 is the stronger of the two: tensile strength 2,300 MPa (334 ksi) against 900 MPa (131 ksi) for M62-A, about 156% more. In exchange, M62-A is the more ductile: elongation 12% versus 0.5% for M62 QT64-66, and M62 QT64-66 is harder (65 HRC vs 25 HRC). M62 QT64-66 runs hotter in service (600°C vs 500°C continuous) and M62-A conducts heat better (24 W/m·K vs 21 W/m·K). On the shop floor, M62-A machines more easily (poor vs not recommended) and M62-A welds better (poor vs not recommended).
M62-AChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
M62 QT64-66Choose it when strength drives the design, or when the part sees heat.
M62-A vs M62 QT64-66: 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.
Tensile Strength (Ultimate)
Elongation at Break
Compressive Strength
Fatigue Strength (Endurance Limit)
Hardness, Rockwell C
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 221 GPa32.1 Msi · Shear Modulus 85 GPa12.3 Msi · Bulk Modulus 168 GPa24.4 Msi · Poisson's Ratio 0.29 · Yield Strength (0.2% offset) 560 MPa81.2 ksi · Reduction in Area 20% · Shear Strength 600 MPa87 ksi · Hardness, Brinell 255 HB · Hardness, Rockwell B 102 HRB
Physical
Density and transition temperatures.
Same in both: Density 8.16 g/cm³0.29 lb/in³ · Melting Point (Solidus) 1,230°C2,246 °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) 10.8 µm/m·K6 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).
Corrosion Resistance
Same in both: Galvanic Potential (seawater, vs SCE) -0.45 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 25 / 100 · Brazeability / Solderability 55 / 100 · Polishability 70 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 78 MJ/kg33,534 BTU/lb · Embodied Carbon (primary production) 5.6 kg CO₂/kg · Embodied Water 90 L/kg10.8 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.
M62-A vs M62 QT64-66 — frequently asked
Is M62 QT64-66 stronger than M62-A?
Yes. M62 QT64-66 has a typical tensile strength of 2,300 MPa (334 ksi) against 900 MPa (131 ksi) for M62-A — about 156% more.
Which condition does FabDigit quote by default, A or QT64-66?
A is the default M62 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, M62-A or M62 QT64-66?
M62-A. Its machinability rates poor (28/100) against not recommended (8/100) for M62 QT64-66; for welding the order is M62-A first (poor, 20/100) then M62 QT64-66 (not recommended, 10/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in M62-A and M62 QT64-66 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.