Steel SUH660-ST vs SUH660-STA
Steel · SUH660 temper comparison
SUH660-ST and SUH660-STA are two conditions of the same steel grade, SUH660: ST (solution annealed) versus STA (solution treated and aged). The chemistry is identical, so every difference below comes from the condition. SUH660-STA is the stronger of the two: yield strength 725 MPa (105 ksi) against 285 MPa (41.3 ksi) for SUH660-ST, about 154% more; tensile strength follows at 1,010 MPa (146 ksi) vs 655 MPa (95 ksi). In exchange, SUH660-ST is the more ductile: elongation 45% versus 22% for SUH660-STA, and SUH660-STA is harder (290 HB vs 190 HB). SUH660-STA runs hotter in service (700°C vs 600°C continuous). On the shop floor, SUH660-ST machines more easily (30 vs 20 out of 100) and SUH660-ST welds better (65 vs 55 out of 100).
SUH660-STChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
SUH660-STAChoose it when strength drives the design, or when the part sees heat.
SUH660-ST vs SUH660-STA: 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
Fatigue Strength (Endurance Limit)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Same in both: Elastic (Young's) Modulus 201 GPa29.2 Msi · Shear Modulus 77 GPa11.2 Msi · Bulk Modulus 176 GPa25.5 Msi · Poisson's Ratio 0.31 · Compressive Strength 740 MPa107 ksi · Shear Strength 620 MPa89.9 ksi · Fracture Toughness (K_IC) 130 MPa·√m118 ksi·√in · Hardness, Rockwell C 30 HRC · Hardness, Vickers 305 HV
Physical
Density and transition temperatures.
Same in both: Density 7.94 g/cm³0.29 lb/in³ · Melting Point (Solidus) 1,370°C2,498 °F · Liquidus Temperature 1,400°C2,552 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 13 W/m·K7.5 BTU/hr·ft·°F · Specific Heat Capacity 460 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 16.4 µm/m·K9.1 µin/in·°F · Latent Heat of Fusion 285 J/g123 BTU/lb · Min Service Temperature -196°C-321 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 1.9 % IACS · Electrical Resistivity 9.1×10⁻⁷ Ω·m35.8 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.1 V · Corrosion Resistance 58 / 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 60 / 100 · Polishability 75 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 90 MJ/kg38,693 BTU/lb · Embodied Carbon (primary production) 6.5 kg CO₂/kg · Embodied Water 220 L/kg26.4 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.
SUH660-ST vs SUH660-STA — frequently asked
Is SUH660-STA stronger than SUH660-ST?
Yes. SUH660-STA has a typical yield strength of 725 MPa (105 ksi) against 285 MPa (41.3 ksi) for SUH660-ST — about 154% more. Tensile strength is 1,010 MPa (146 ksi) vs 655 MPa (95 ksi).
Which condition does FabDigit quote by default, ST or STA?
STA is the default SUH660 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, SUH660-ST or SUH660-STA?
SUH660-ST, by a small margin. Both rate poor for machinability — 30/100 against 20/100 for SUH660-STA; for welding the order is SUH660-ST first (good, 65/100) then SUH660-STA (good, 55/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in SUH660-ST and SUH660-STA 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.