Steel A8 Q&T vs A8 Stress Relieved
Steel · A8 temper comparison
A8 Q&T and A8 Stress Relieved are two conditions of the same steel grade, A8: Q&T (quenched and tempered) versus Stress Relieved. The chemistry is identical, so every difference below comes from the condition. A8 Q&T is the stronger of the two: yield strength 1,700 MPa (247 ksi) against 510 MPa (74 ksi) for A8 Stress Relieved, about 3.3 times as much; tensile strength follows at 2,000 MPa (290 ksi) vs 790 MPa (115 ksi). In exchange, A8 Stress Relieved is the more ductile: elongation 17% versus 2% for A8 Q&T, and A8 Q&T is harder (675 HV vs 236 HV). A8 Q&T runs hotter in service (425°C vs 200°C continuous). On the shop floor, A8 Stress Relieved machines more easily (fair vs not recommended).
A8 Q&TChoose it when strength drives the design, or when the part sees heat.
A8 Stress RelievedChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
A8 Q&T vs A8 Stress Relieved: 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
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 207 GPa30 Msi · Shear Modulus 80 GPa11.6 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29
Physical
Density and transition temperatures.
Same in both: Density 7.83 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,420°C2,588 °F · Liquidus Temperature 1,470°C2,678 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 24.5 W/m·K14.2 BTU/hr·ft·°F · Specific Heat Capacity 460 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 12.4 µm/m·K6.9 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 2.9 % IACS · Electrical Resistivity 6×10⁻⁷ Ω·m23.6 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Corrosion Resistance 20 / 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: Brazeability / Solderability 35 / 100 · Polishability 65 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 34 MJ/kg14,617 BTU/lb · Embodied Carbon (primary production) 2.6 kg CO₂/kg · Embodied Water 70 L/kg8.4 gal/lb · Typical Recycled Content 40%
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.
A8 Q&T vs A8 Stress Relieved — frequently asked
Is A8 Q&T stronger than A8 Stress Relieved?
Yes. A8 Q&T has a typical yield strength of 1,700 MPa (247 ksi) against 510 MPa (74 ksi) for A8 Stress Relieved — about 3.3 times as much. Tensile strength is 2,000 MPa (290 ksi) vs 790 MPa (115 ksi).
Which condition does FabDigit quote by default, Q&T or Stress Relieved?
Annealed is the default A8 condition in the FabDigit quote flow (neither Q&T nor Stress Relieved). 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, A8 Q&T or A8 Stress Relieved?
A8 Stress Relieved. Its machinability rates fair (44/100) against not recommended (10/100) for A8 Q&T.
Ready to make it?
Upload a CAD file and FabDigit prices the part in A8 Q&T and A8 Stress Relieved 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.