Steel 5145-A vs 5145-QT205
Steel · 5145 temper comparison
5145-A and 5145-QT205 are two conditions of the same steel grade, 5145: A (solution annealed) versus QT205 (OQ&T 205 °C). The chemistry is identical, so every difference below comes from the condition. 5145-QT205 is the stronger of the two: yield strength 1,660 MPa (241 ksi) against 340 MPa (49.3 ksi) for 5145-A, about 4.9 times as much; tensile strength follows at 1,930 MPa (280 ksi) vs 620 MPa (89.9 ksi). In exchange, 5145-A is the more ductile: elongation 25% versus 9% for 5145-QT205, and 5145-QT205 is harder (520 HB vs 180 HB). 5145-A runs hotter in service (400°C vs 160°C continuous). On the shop floor, 5145-A machines more easily (good vs poor) and 5145-A welds better (fair vs poor).
5145-AChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
5145-QT205Choose it when strength drives the design.
5145-A vs 5145-QT205: 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)
Charpy V-Notch Impact (RT)
Hardness, Brinell
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 · Hardness, Rockwell B 88 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 46 W/m·K26.6 BTU/hr·ft·°F · Specific Heat Capacity 475 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 250 J/g107 BTU/lb · Min Service Temperature -30°C-22 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 7.8 % IACS · Electrical Resistivity 2.2×10⁻⁷ Ω·m8.66 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.62 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
Same in both: Formability (cold) 45 / 100 · Brazeability / Solderability 55 / 100 · Polishability 60 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 34 MJ/kg14,617 BTU/lb · Embodied Carbon (primary production) 2.3 kg CO₂/kg · Embodied Water 60 L/kg7.2 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.
5145-A vs 5145-QT205 — frequently asked
Is 5145-QT205 stronger than 5145-A?
Yes. 5145-QT205 has a typical yield strength of 1,660 MPa (241 ksi) against 340 MPa (49.3 ksi) for 5145-A — about 4.9 times as much. Tensile strength is 1,930 MPa (280 ksi) vs 620 MPa (89.9 ksi).
Which condition does FabDigit quote by default, A or QT205?
A is the default 5145 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, 5145-A or 5145-QT205?
5145-A. Its machinability rates good (58/100) against poor (22/100) for 5145-QT205; for welding the order is 5145-A first (fair, 35/100) then 5145-QT205 (poor, 15/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 5145-A and 5145-QT205 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.