Stainless Steel 309S-1/4 Hard vs 309S Annealed
Stainless Steel · 309S temper comparison
309S-1/4 Hard and 309S Annealed are two conditions of the same stainless steel grade, 309S: 1/4 Hard (quarter hard) versus Annealed. The chemistry is identical, so every difference below comes from the condition. 309S-1/4 Hard is the stronger of the two: yield strength 520 MPa (75.4 ksi) against 270 MPa (39.2 ksi) for 309S Annealed, about 93% more; tensile strength follows at 760 MPa (110 ksi) vs 540 MPa (78.3 ksi). In exchange, 309S Annealed is the more ductile: elongation 45% versus 20% for 309S-1/4 Hard, and 309S-1/4 Hard is harder (240 HB vs 160 HB). 309S Annealed runs hotter in service (1,000°C vs 850°C continuous).
309S-1/4 HardChoose it when strength drives the design.
309S AnnealedChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
309S-1/4 Hard vs 309S Annealed: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all stainless 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 stainless 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, Rockwell B
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 200 GPa29 Msi · Shear Modulus 77 GPa11.2 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.3
Physical
Density and transition temperatures.
Same in both: Density 7.9 g/cm³0.29 lb/in³ · Melting Point (Solidus) 1,400°C2,552 °F · Liquidus Temperature 1,450°C2,642 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 15.5 W/m·K9 BTU/hr·ft·°F · Specific Heat Capacity 500 J/kg·K0.12 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 15 µm/m·K8.3 µin/in·°F · Latent Heat of Fusion 270 J/g116 BTU/lb · Min Service Temperature -196°C-321 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 2.2 % IACS · Electrical Resistivity 7.8×10⁻⁷ Ω·m30.7 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Same in both: Galvanic Potential (seawater, vs SCE) -0.05 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 65 / 100 · Polishability 70 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 62 MJ/kg26,655 BTU/lb · Embodied Carbon (primary production) 4.6 kg CO₂/kg · Embodied Water 300 L/kg35.9 gal/lb · Typical Recycled Content 60%
Strength versus weight
Yield strength against density for every stainless steel grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
309S-1/4 Hard vs 309S Annealed — frequently asked
Is 309S-1/4 Hard stronger than 309S Annealed?
Yes. 309S-1/4 Hard has a typical yield strength of 520 MPa (75.4 ksi) against 270 MPa (39.2 ksi) for 309S Annealed — about 93% more. Tensile strength is 760 MPa (110 ksi) vs 540 MPa (78.3 ksi).
Which condition does FabDigit quote by default, 1/4 Hard or Annealed?
Solution Annealed is the default 309S condition in the FabDigit quote flow (neither 1/4 Hard nor Annealed). 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, 309S-1/4 Hard or 309S Annealed?
309S Annealed. Its machinability rates fair (38/100) against poor (32/100) for 309S-1/4 Hard; for welding the order is 309S Annealed first (very good, 80/100) then 309S-1/4 Hard (very good, 75/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 309S-1/4 Hard and 309S Annealed 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.