Steel 20CrMo4 +A vs 20CrMo4 QT-300HB
Steel · 20CrMo4 temper comparison
20CrMo4 +A and 20CrMo4 QT-300HB are two conditions of the same steel grade, 20CrMo4: +A (annealed) versus QT-300HB (Q&T). The chemistry is identical, so every difference below comes from the condition. 20CrMo4 QT-300HB is the stronger of the two: yield strength 800 MPa (116 ksi) against 360 MPa (52.2 ksi) for 20CrMo4 +A, about 122% more; tensile strength follows at 1,000 MPa (145 ksi) vs 570 MPa (82.7 ksi). In exchange, 20CrMo4 +A is the more ductile: elongation 22% versus 14% for 20CrMo4 QT-300HB, and 20CrMo4 QT-300HB is harder (300 HB vs 170 HB). On the shop floor, 20CrMo4 +A machines more easily (good vs fair).
20CrMo4 +AChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
20CrMo4 QT-300HBChoose it when strength drives the design.
20CrMo4 +A vs 20CrMo4 QT-300HB: 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
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Hardness, Brinell
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 210 GPa30.5 Msi · Shear Modulus 80 GPa11.6 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Compressive Strength 360 MPa52.2 ksi · Shear Strength 350 MPa50.8 ksi · Charpy V-Notch Impact (RT) 60 J44.3 ft·lbf · Hardness, Rockwell B 87 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 1,500°C2,732 °F
Thermal
How each material carries heat and how hot it can run.
Same in both: Thermal Conductivity 42 W/m·K24.3 BTU/hr·ft·°F · 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 · Max Service Temperature (continuous) 400°C752 °F · Min Service Temperature -40°C-40 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 7.5 % IACS · Electrical Resistivity 2.3×10⁻⁷ Ω·m9.06 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.61 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 %)
Same in both: Weldability 55 / 100 · Formability (cold) 60 / 100 · Brazeability / Solderability 65 / 100 · Polishability 60 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 30 MJ/kg12,898 BTU/lb · Embodied Carbon (primary production) 2.1 kg CO₂/kg · Embodied Water 55 L/kg6.6 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.
20CrMo4 +A vs 20CrMo4 QT-300HB — frequently asked
Is 20CrMo4 QT-300HB stronger than 20CrMo4 +A?
Yes. 20CrMo4 QT-300HB has a typical yield strength of 800 MPa (116 ksi) against 360 MPa (52.2 ksi) for 20CrMo4 +A — about 122% more. Tensile strength is 1,000 MPa (145 ksi) vs 570 MPa (82.7 ksi).
Which condition does FabDigit quote by default, +A or QT-300HB?
+A is the default 20CrMo4 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, 20CrMo4 +A or 20CrMo4 QT-300HB?
20CrMo4 +A. Its machinability rates good (55/100) against fair (40/100) for 20CrMo4 QT-300HB.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 20CrMo4 +A and 20CrMo4 QT-300HB 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.