Steel SK5-HR vs SK5 Q&T
Steel · SK5 temper comparison
SK5-HR and SK5 Q&T are two conditions of the same steel grade, SK5: HR (hot rolled) versus Q&T (quenched and tempered). The chemistry is identical, so every difference below comes from the condition. SK5 Q&T is the stronger of the two: yield strength 1,650 MPa (239 ksi) against 400 MPa (58 ksi) for SK5-HR, about 4.1 times as much; tensile strength follows at 2,000 MPa (290 ksi) vs 710 MPa (103 ksi). In exchange, SK5-HR is the more ductile: elongation 12% versus 2% for SK5 Q&T, and SK5 Q&T is harder (700 HV vs 210 HV). SK5-HR runs hotter in service (350°C vs 180°C continuous). On the shop floor, SK5-HR machines more easily (fair vs not recommended) and SK5-HR welds better (poor vs not recommended).
SK5-HRChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
SK5 Q&TChoose it when strength drives the design.
SK5-HR vs SK5 Q&T: 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)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 205 GPa29.7 Msi · Shear Modulus 80 GPa11.6 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Hardness, Brinell 200 HB · Hardness, Rockwell B 93 HRB
Physical
Density and transition temperatures.
Same in both: Density 7.82 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,425°C2,597 °F · Liquidus Temperature 1,470°C2,678 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 48 W/m·K27.7 BTU/hr·ft·°F · Specific Heat Capacity 475 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 11.5 µm/m·K6.4 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Min Service Temperature -20°C-4 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 9.5 % IACS · Electrical Resistivity 1.8×10⁻⁷ Ω·m7.09 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.61 V · Corrosion Resistance 10 / 100
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 30 / 100 · Brazeability / Solderability 45 / 100 · Polishability 70 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 27 MJ/kg11,608 BTU/lb · Embodied Carbon (primary production) 2.1 kg CO₂/kg · Embodied Water 45 L/kg5.4 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.
SK5-HR vs SK5 Q&T — frequently asked
Is SK5 Q&T stronger than SK5-HR?
Yes. SK5 Q&T has a typical yield strength of 1,650 MPa (239 ksi) against 400 MPa (58 ksi) for SK5-HR — about 4.1 times as much. Tensile strength is 2,000 MPa (290 ksi) vs 710 MPa (103 ksi).
Which condition does FabDigit quote by default, HR or Q&T?
HR is the default SK5 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, SK5-HR or SK5 Q&T?
SK5-HR. Its machinability rates fair (36/100) against not recommended (8/100) for SK5 Q&T; for welding the order is SK5-HR first (poor, 18/100) then SK5 Q&T (not recommended, 8/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in SK5-HR and SK5 Q&T 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.