Stainless Steel CA15-AC vs CA15-QT315
Stainless Steel · CA15 temper comparison
CA15-AC and CA15-QT315 are two conditions of the same stainless steel grade, CA15: AC (spheroidize annealed) versus QT315 (Q&T). The chemistry is identical, so every difference below comes from the condition. CA15-QT315 is the stronger of the two: yield strength 900 MPa (131 ksi) against 620 MPa (89.9 ksi) for CA15-AC, about 45% more; tensile strength follows at 1,100 MPa (160 ksi) vs 800 MPa (116 ksi). CA15-QT315 is the more ductile: elongation 11% versus 8% for CA15-AC, and CA15-QT315 is harder (350 HB vs 300 HB). CA15-AC runs hotter in service (400°C vs 250°C continuous). On the shop floor, CA15-QT315 welds better (fair vs poor).
CA15-ACChoose it when the part sees heat.
CA15-QT315Choose it when strength drives the design, or when the part is bent, formed or impact-loaded.
CA15-AC vs CA15-QT315: 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
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell C
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 200 GPa29 Msi · Shear Modulus 78 GPa11.3 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.28
Physical
Density and transition temperatures.
Same in both: Density 7.61 g/cm³0.27 lb/in³ · Melting Point (Solidus) 1,480°C2,696 °F · Liquidus Temperature 1,530°C2,786 °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 460 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 10.3 µm/m·K5.7 µin/in·°F · Latent Heat of Fusion 270 J/g116 BTU/lb · Min Service Temperature -29°C-20 °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) -0.3 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: Castability 70 / 100 · Brazeability / Solderability 40 / 100 · Polishability 65 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 40 MJ/kg17,197 BTU/lb · Embodied Carbon (primary production) 3.6 kg CO₂/kg · Embodied Water 180 L/kg21.6 gal/lb · Typical Recycled Content 75%
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.
CA15-AC vs CA15-QT315 — frequently asked
Is CA15-QT315 stronger than CA15-AC?
Yes. CA15-QT315 has a typical yield strength of 900 MPa (131 ksi) against 620 MPa (89.9 ksi) for CA15-AC — about 45% more. Tensile strength is 1,100 MPa (160 ksi) vs 800 MPa (116 ksi).
Which condition does FabDigit quote by default, AC or QT315?
NT650 is the default CA15 condition in the FabDigit quote flow (neither AC nor QT315). 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 welds better, CA15-AC or CA15-QT315?
CA15-QT315. Its weldability rates fair (40/100) against poor (25/100) for CA15-AC.
Ready to make it?
Upload a CAD file and FabDigit prices the part in CA15-AC and CA15-QT315 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.