Steel 15MnB-A vs 15MnB-QT
Steel · 15MnB temper comparison
15MnB-A and 15MnB-QT are two conditions of the same steel grade, 15MnB: A (solution annealed) versus QT (quenched and tempered). The chemistry is identical, so every difference below comes from the condition. 15MnB-QT is the stronger of the two: yield strength 660 MPa (95.7 ksi) against 310 MPa (45 ksi) for 15MnB-A, about 113% more; tensile strength follows at 830 MPa (120 ksi) vs 510 MPa (74 ksi). In exchange, 15MnB-A is the more ductile: elongation 26% versus 16% for 15MnB-QT, and 15MnB-QT is harder (250 HB vs 156 HB). 15MnB-QT runs hotter in service (450°C vs 350°C continuous). On the shop floor, 15MnB-A welds better (very good vs good).
15MnB-AChoose it when the part is bent, formed or impact-loaded, or when it will be welded.
15MnB-QTChoose it when strength drives the design, or when the part sees heat.
15MnB-A vs 15MnB-QT: 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
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Hardness, Brinell
Hardness, Rockwell B
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 · Charpy V-Notch Impact (RT) 75 J55.3 ft·lbf
Physical
Density and transition temperatures.
Same in both: Density 7.85 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,425°C2,597 °F · Liquidus Temperature 1,500°C2,732 °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) 12.2 µm/m·K6.8 µin/in·°F · Latent Heat of Fusion 270 J/g116 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) -0.62 V · Corrosion Resistance 11 / 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 30 / 100 · Brazeability / Solderability 65 / 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 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.
15MnB-A vs 15MnB-QT — frequently asked
Is 15MnB-QT stronger than 15MnB-A?
Yes. 15MnB-QT has a typical yield strength of 660 MPa (95.7 ksi) against 310 MPa (45 ksi) for 15MnB-A — about 113% more. Tensile strength is 830 MPa (120 ksi) vs 510 MPa (74 ksi).
Which condition does FabDigit quote by default, A or QT?
HR is the default 15MnB condition in the FabDigit quote flow (neither A nor QT). 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 welds better, 15MnB-A or 15MnB-QT?
15MnB-A. Its weldability rates very good (75/100) against good (55/100) for 15MnB-QT.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 15MnB-A and 15MnB-QT 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.