Steel H12-HR vs H12-QT48
Steel · H12 temper comparison
H12-HR and H12-QT48 are two conditions of the same steel grade, H12: HR (hot rolled) versus QT48 (hardened & tempered to 47–49 HRC). The chemistry is identical, so every difference below comes from the condition. H12-QT48 is the stronger of the two: yield strength 1,400 MPa (203 ksi) against 800 MPa (116 ksi) for H12-HR, about 75% more; tensile strength follows at 1,600 MPa (232 ksi) vs 1,000 MPa (145 ksi). In exchange, H12-HR is the more ductile: elongation 12% versus 9% for H12-QT48, and H12-HR is harder (300 HB vs 210 HB). H12-QT48 runs hotter in service (540°C vs 450°C continuous). On the shop floor, H12-HR machines more easily (30 vs 18 out of 100) and H12-QT48 welds better (25 vs 15 out of 100).
H12-HRChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
H12-QT48Choose it when strength drives the design, or when the part sees heat.
H12-HR vs H12-QT48: 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
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 210 GPa30.5 Msi · Shear Modulus 81 GPa11.7 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Reduction in Area 35% · Hardness, Rockwell B 95 HRB
Physical
Density and transition temperatures.
Same in both: Density 7.8 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,425°C2,597 °F · Liquidus Temperature 1,465°C2,669 °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 460 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 -30°C-22 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 3.3 % IACS · Electrical Resistivity 5.2×10⁻⁷ Ω·m20.5 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.6 V · Corrosion Resistance 20 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Polishability
Same in both: Castability 25 / 100 · Brazeability / Solderability 40 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 33 MJ/kg14,187 BTU/lb · Embodied Carbon (primary production) 2.5 kg CO₂/kg · Embodied Water 60 L/kg7.2 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.
H12-HR vs H12-QT48 — frequently asked
Is H12-QT48 stronger than H12-HR?
Yes. H12-QT48 has a typical yield strength of 1,400 MPa (203 ksi) against 800 MPa (116 ksi) for H12-HR — about 75% more. Tensile strength is 1,600 MPa (232 ksi) vs 1,000 MPa (145 ksi).
Which condition does FabDigit quote by default, HR or QT48?
ANN is the default H12 condition in the FabDigit quote flow (neither HR nor QT48). 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, H12-HR or H12-QT48?
H12-HR, by a small margin. Both rate poor for machinability — 30/100 against 18/100 for H12-QT48; for welding the order is H12-QT48 first (poor, 25/100) then H12-HR (poor, 15/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in H12-HR and H12-QT48 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.