Steel SKH2-A vs SKH2 QT64-66HRC
Steel · SKH2 temper comparison
SKH2-A and SKH2 QT64-66HRC are two conditions of the same steel grade, SKH2: A (solution annealed) versus QT64-66HRC (hardened & triple tempered to 64–66 HRC). The chemistry is identical, so every difference below comes from the condition. SKH2 QT64-66HRC is the stronger of the two: tensile strength 2,300 MPa (334 ksi) against 880 MPa (128 ksi) for SKH2-A, about 161% more. SKH2 QT64-66HRC is harder — 840 HV against 253 HV for SKH2-A — which matters for wear surfaces and threads. SKH2 QT64-66HRC runs hotter in service (600°C vs 300°C continuous). On the shop floor, SKH2-A machines more easily (fair vs not recommended).
SKH2-AChoose it when the part is machined in volume.
SKH2 QT64-66HRCChoose it when strength drives the design, or when surface hardness matters.
SKH2-A vs SKH2 QT64-66HRC: 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)
Compressive Strength
Charpy V-Notch Impact (RT)
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 220 GPa31.9 Msi · Shear Modulus 85 GPa12.3 Msi · Bulk Modulus 167 GPa24.2 Msi · Poisson's Ratio 0.28 · Yield Strength (0.2% offset) 540 MPa78.3 ksi · Elongation at Break 18% · Reduction in Area 30% · Shear Strength 550 MPa79.8 ksi · Hardness, Brinell 240 HB · Hardness, Rockwell B 99 HRB
Physical
Density and transition temperatures.
Same in both: Density 8.67 g/cm³0.31 lb/in³ · Melting Point (Solidus) 1,290°C2,354 °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 21 W/m·K12.1 BTU/hr·ft·°F · Specific Heat Capacity 420 J/kg·K0.1 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 10.6 µm/m·K5.9 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) -0.45 V · Corrosion Resistance 22 / 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 18 / 100 · Formability (cold) 12 / 100 · Brazeability / Solderability 60 / 100 · Polishability 80 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 48 MJ/kg20,636 BTU/lb · Embodied Carbon (primary production) 3.4 kg CO₂/kg · Embodied Water 70 L/kg8.4 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.
SKH2-A vs SKH2 QT64-66HRC — frequently asked
Is SKH2 QT64-66HRC stronger than SKH2-A?
Yes. SKH2 QT64-66HRC has a typical tensile strength of 2,300 MPa (334 ksi) against 880 MPa (128 ksi) for SKH2-A — about 161% more.
Which condition does FabDigit quote by default, A or QT64-66HRC?
A is the default SKH2 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, SKH2-A or SKH2 QT64-66HRC?
SKH2-A. Its machinability rates fair (35/100) against not recommended (5/100) for SKH2 QT64-66HRC.
Ready to make it?
Upload a CAD file and FabDigit prices the part in SKH2-A and SKH2 QT64-66HRC 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.