Steel ZG55SiMnMo-F vs ZG55SiMnMo QT50-55HRC
Steel · ZG55SiMnMo temper comparison
ZG55SiMnMo-F and ZG55SiMnMo QT50-55HRC are two conditions of the same steel grade, ZG55SiMnMo: F (as fabricated) versus QT50-55HRC. The chemistry is identical, so every difference below comes from the condition. ZG55SiMnMo QT50-55HRC is the stronger of the two: yield strength 1,450 MPa (210 ksi) against 430 MPa (62.4 ksi) for ZG55SiMnMo-F, about 3.4 times as much; tensile strength follows at 1,800 MPa (261 ksi) vs 750 MPa (109 ksi). In exchange, ZG55SiMnMo-F is the more ductile: elongation 6% versus 3% for ZG55SiMnMo QT50-55HRC, and ZG55SiMnMo QT50-55HRC is harder (530 HB vs 260 HB). ZG55SiMnMo-F runs hotter in service (400°C vs 200°C continuous). On the shop floor, ZG55SiMnMo-F machines more easily (poor vs not recommended).
ZG55SiMnMo-FChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
ZG55SiMnMo QT50-55HRCChoose it when strength drives the design.
ZG55SiMnMo-F vs ZG55SiMnMo QT50-55HRC: 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.
ZG55SiMnMo-FZG55SiMnMo QT50-55HRC
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)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell C
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 · Fracture Toughness (K_IC) 32 MPa·√m29.1 ksi·√in
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 1,480°C2,696 °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) 12 µm/m·K6.7 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Min Service Temperature -30°C-22 °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 %)
Weldability
Formability (cold)
Same in both: Castability 60 / 100 · Brazeability / Solderability 30 / 100 · Polishability 55 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 26 MJ/kg11,178 BTU/lb · Embodied Carbon (primary production) 2 kg CO₂/kg · Embodied Water 40 L/kg4.8 gal/lb · Typical Recycled Content 80%
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.
ZG55SiMnMo-F vs ZG55SiMnMo QT50-55HRC — frequently asked
Is ZG55SiMnMo QT50-55HRC stronger than ZG55SiMnMo-F?
Yes. ZG55SiMnMo QT50-55HRC has a typical yield strength of 1,450 MPa (210 ksi) against 430 MPa (62.4 ksi) for ZG55SiMnMo-F — about 3.4 times as much. Tensile strength is 1,800 MPa (261 ksi) vs 750 MPa (109 ksi).
Which condition does FabDigit quote by default, F or QT50-55HRC?
QT45-50HRC is the default ZG55SiMnMo condition in the FabDigit quote flow (neither F nor QT50-55HRC). 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, ZG55SiMnMo-F or ZG55SiMnMo QT50-55HRC?
ZG55SiMnMo-F. Its machinability rates poor (30/100) against not recommended (8/100) for ZG55SiMnMo QT50-55HRC; for welding the order is ZG55SiMnMo-F first (poor, 30/100) then ZG55SiMnMo QT50-55HRC (poor, 25/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in ZG55SiMnMo-F and ZG55SiMnMo QT50-55HRC 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.