Stainless Steel CA15M-AC vs CA15M-QT650
Stainless Steel · CA15M temper comparison
CA15M-AC and CA15M-QT650 are two conditions of the same stainless steel grade, CA15M: AC (spheroidize annealed) versus QT650. The chemistry is identical, so every difference below comes from the condition. CA15M-AC is the stronger of the two: yield strength 690 MPa (100 ksi) against 490 MPa (71.1 ksi) for CA15M-QT650, about 41% more; tensile strength follows at 900 MPa (131 ksi) vs 690 MPa (100 ksi). In exchange, CA15M-QT650 is the more ductile: elongation 25% versus 6% for CA15M-AC, and CA15M-AC is harder (380 HB vs 200 HB). CA15M-QT650 runs hotter in service (650°C vs 300°C continuous). On the shop floor, CA15M-QT650 machines more easily (fair vs poor) and CA15M-QT650 welds better (fair vs poor).
CA15M-ACChoose it when strength drives the design.
CA15M-QT650Choose it when the part is bent, formed or impact-loaded, or when the part sees heat.
CA15M-AC vs CA15M-QT650: 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 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) 1,450°C2,642 °F · Liquidus Temperature 1,510°C2,750 °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) 10.8 µm/m·K6 µin/in·°F · Latent Heat of Fusion 270 J/g116 BTU/lb · Min Service Temperature -30°C-22 °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 45 / 100 · Polishability 70 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 53 MJ/kg22,786 BTU/lb · Embodied Carbon (primary production) 4 kg CO₂/kg · Embodied Water 130 L/kg15.6 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.
CA15M-AC vs CA15M-QT650 — frequently asked
Is CA15M-AC stronger than CA15M-QT650?
Yes. CA15M-AC has a typical yield strength of 690 MPa (100 ksi) against 490 MPa (71.1 ksi) for CA15M-QT650 — about 41% more. Tensile strength is 900 MPa (131 ksi) vs 690 MPa (100 ksi).
Which condition does FabDigit quote by default, AC or QT650?
NT595 is the default CA15M condition in the FabDigit quote flow (neither AC nor QT650). 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, CA15M-AC or CA15M-QT650?
CA15M-QT650. Its machinability rates fair (50/100) against poor (20/100) for CA15M-AC; for welding the order is CA15M-QT650 first (fair, 40/100) then CA15M-AC (poor, 15/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in CA15M-AC and CA15M-QT650 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.