Steel S4 Annealed vs S4-AQ
Steel · S4 temper comparison
S4 Annealed and S4-AQ are two conditions of the same steel grade, S4: Annealed versus AQ (as-quenched). The chemistry is identical, so every difference below comes from the condition. S4-AQ is the stronger of the two: yield strength 1,900 MPa (276 ksi) against 430 MPa (62.4 ksi) for S4 Annealed, about 4.4 times as much; tensile strength follows at 2,200 MPa (319 ksi) vs 720 MPa (104 ksi). In exchange, S4 Annealed is the more ductile: elongation 25% versus 1% for S4-AQ. S4 Annealed runs hotter in service (400°C vs 150°C continuous) and S4 Annealed conducts heat better (25 W/m·K vs 21 W/m·K). On the shop floor, S4 Annealed machines more easily (fair vs not recommended) and S4 Annealed welds better (poor vs not recommended).
S4 AnnealedChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
S4-AQChoose it when strength drives the design.
S4 Annealed vs S4-AQ: 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
Shear Strength
Fatigue Strength (Endurance Limit)
Charpy V-Notch Impact (RT)
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 · Hardness, Brinell 210 HB · Hardness, Rockwell B 95 HRB
Physical
Density and transition temperatures.
Same in both: Density 7.79 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) 12.4 µm/m·K6.9 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Min Service Temperature -40°C-40 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Same in both: Galvanic Potential (seawater, vs SCE) -0.55 V
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 45 / 100 · Polishability 55 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 33 MJ/kg14,187 BTU/lb · Embodied Carbon (primary production) 2.4 kg CO₂/kg · Embodied Water 65 L/kg7.8 gal/lb · Typical Recycled Content 35%
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.
S4 Annealed vs S4-AQ — frequently asked
Is S4-AQ stronger than S4 Annealed?
Yes. S4-AQ has a typical yield strength of 1,900 MPa (276 ksi) against 430 MPa (62.4 ksi) for S4 Annealed — about 4.4 times as much. Tensile strength is 2,200 MPa (319 ksi) vs 720 MPa (104 ksi).
Which condition does FabDigit quote by default, Annealed or AQ?
Annealed is the default S4 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, S4 Annealed or S4-AQ?
S4 Annealed. Its machinability rates fair (48/100) against not recommended (5/100) for S4-AQ; for welding the order is S4 Annealed first (poor, 22/100) then S4-AQ (not recommended, 3/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in S4 Annealed and S4-AQ 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.