Steel 30CrMnSiNi2A-QT400 vs 30CrMnSiNi2A-QT520
Steel · 30CrMnSiNi2A temper comparison
30CrMnSiNi2A-QT400 and 30CrMnSiNi2A-QT520 are two conditions of the same steel grade, 30CrMnSiNi2A: QT400 (Q&T 400 °C) versus QT520 (Q&T 500–550 °C). The chemistry is identical, so every difference below comes from the condition. 30CrMnSiNi2A-QT400 is the stronger of the two: yield strength 1,350 MPa (196 ksi) against 1,150 MPa (167 ksi) for 30CrMnSiNi2A-QT520, about 17% more; tensile strength follows at 1,500 MPa (218 ksi) vs 1,280 MPa (186 ksi). In exchange, 30CrMnSiNi2A-QT520 is the more ductile: elongation 15% versus 12% for 30CrMnSiNi2A-QT400, and 30CrMnSiNi2A-QT400 is harder (44 HRC vs 39 HRC). 30CrMnSiNi2A-QT520 runs hotter in service (430°C vs 350°C continuous).
30CrMnSiNi2A-QT400Choose it when strength drives the design.
30CrMnSiNi2A-QT520Choose it when the part is bent, formed or impact-loaded, or when the part sees heat.
30CrMnSiNi2A-QT400 vs 30CrMnSiNi2A-QT520: 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.
30CrMnSiNi2A-QT40030CrMnSiNi2A-QT520
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, Rockwell C
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 200 GPa29 Msi · Shear Modulus 78 GPa11.3 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.3
Physical
Density and transition temperatures.
Same in both: Density 7.8 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.
Thermal Conductivity
Max Service Temperature (continuous)
Same in both: Specific Heat Capacity 470 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 -60°C-76 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.6 V · Corrosion Resistance 12 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Formability (cold)
Same in both: Weldability 20 / 100 · Brazeability / Solderability 30 / 100 · Polishability 70 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 34 MJ/kg14,617 BTU/lb · Embodied Carbon (primary production) 2.5 kg CO₂/kg · Embodied Water 60 L/kg7.2 gal/lb · Typical Recycled Content 20%
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.
30CrMnSiNi2A-QT400 vs 30CrMnSiNi2A-QT520 — frequently asked
Is 30CrMnSiNi2A-QT400 stronger than 30CrMnSiNi2A-QT520?
Yes. 30CrMnSiNi2A-QT400 has a typical yield strength of 1,350 MPa (196 ksi) against 1,150 MPa (167 ksi) for 30CrMnSiNi2A-QT520 — about 17% more. Tensile strength is 1,500 MPa (218 ksi) vs 1,280 MPa (186 ksi).
Which condition does FabDigit quote by default, QT400 or QT520?
QT260 is the default 30CrMnSiNi2A condition in the FabDigit quote flow (neither QT400 nor QT520). 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, 30CrMnSiNi2A-QT400 or 30CrMnSiNi2A-QT520?
30CrMnSiNi2A-QT520, by a small margin. Both rate poor for machinability — 32/100 against 26/100 for 30CrMnSiNi2A-QT400.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 30CrMnSiNi2A-QT400 and 30CrMnSiNi2A-QT520 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.