Steel 1547 QT-30HRC vs 1547 QT-40HRC
Steel · 1547 temper comparison
1547 QT-30HRC and 1547 QT-40HRC are two conditions of the same steel grade, 1547: QT-30HRC (Q&T) versus QT-40HRC (Q&T). The chemistry is identical, so every difference below comes from the condition. 1547 QT-40HRC is the stronger of the two: yield strength 1,070 MPa (155 ksi) against 760 MPa (110 ksi) for 1547 QT-30HRC, about 41% more; tensile strength follows at 1,240 MPa (180 ksi) vs 950 MPa (138 ksi). In exchange, 1547 QT-30HRC is the more ductile: elongation 15% versus 11% for 1547 QT-40HRC, and 1547 QT-40HRC is harder (375 HB vs 293 HB). 1547 QT-30HRC runs hotter in service (450°C vs 400°C continuous). On the shop floor, 1547 QT-30HRC machines more easily (fair vs poor).
1547 QT-30HRCChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
1547 QT-40HRCChoose it when strength drives the design.
1547 QT-30HRC vs 1547 QT-40HRC: 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
Shear Strength
Fatigue Strength (Endurance Limit)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell C
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 200 GPa29 Msi · Shear Modulus 80 GPa11.6 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Compressive Strength 724 MPa105 ksi · Fracture Toughness (K_IC) 55 MPa·√m50.1 ksi·√in · Hardness, Rockwell B 100 HRB
Physical
Density and transition temperatures.
Same in both: Density 7.85 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,420°C2,588 °F · Liquidus Temperature 1,490°C2,714 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 49 W/m·K28.3 BTU/hr·ft·°F · Specific Heat Capacity 470 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 11.7 µm/m·K6.5 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Min Service Temperature -25°C-13 °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 45 / 100 · Brazeability / Solderability 60 / 100 · Polishability 55 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 25 MJ/kg10,748 BTU/lb · Embodied Carbon (primary production) 2 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.
1547 QT-30HRC vs 1547 QT-40HRC — frequently asked
Is 1547 QT-40HRC stronger than 1547 QT-30HRC?
Yes. 1547 QT-40HRC has a typical yield strength of 1,070 MPa (155 ksi) against 760 MPa (110 ksi) for 1547 QT-30HRC — about 41% more. Tensile strength is 1,240 MPa (180 ksi) vs 950 MPa (138 ksi).
Which condition does FabDigit quote by default, QT-30HRC or QT-40HRC?
CD is the default 1547 condition in the FabDigit quote flow (neither QT-30HRC nor QT-40HRC). 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, 1547 QT-30HRC or 1547 QT-40HRC?
1547 QT-30HRC. Its machinability rates fair (45/100) against poor (30/100) for 1547 QT-40HRC; for welding the order is 1547 QT-30HRC first (poor, 15/100) then 1547 QT-40HRC (not recommended, 10/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 1547 QT-30HRC and 1547 QT-40HRC 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.