Steel C15E +A vs C15E +SR
Steel · C15E temper comparison
C15E +A and C15E +SR are two conditions of the same steel grade, C15E: +A (annealed) versus +SR (stress relieved). The chemistry is identical, so every difference below comes from the condition. C15E +SR is the stronger of the two: yield strength 330 MPa (47.9 ksi) against 285 MPa (41.3 ksi) for C15E +A, about 16% more; tensile strength follows at 410 MPa (59.5 ksi) vs 385 MPa (55.8 ksi). In exchange, C15E +A is the more ductile: elongation 37% versus 21% for C15E +SR, and C15E +SR is harder (120 HB vs 111 HB). C15E +A runs hotter in service (400°C vs 350°C continuous). On the shop floor, C15E +SR machines more easily (50 vs 38 out of 100).
C15E +AChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
C15E +SRChoose it when strength drives the design, or when the part is machined in volume.
C15E +A vs C15E +SR: 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
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 205 GPa29.7 Msi · Shear Modulus 80 GPa11.6 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29
Physical
Density and transition temperatures.
Same in both: Density 7.85 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,460°C2,660 °F · Liquidus Temperature 1,520°C2,768 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 51 W/m·K29.5 BTU/hr·ft·°F · Specific Heat Capacity 480 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 11.9 µm/m·K6.6 µin/in·°F · Latent Heat of Fusion 247 J/g106 BTU/lb · Min Service Temperature -20°C-4 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 10.8 % IACS · Electrical Resistivity 1.6×10⁻⁷ Ω·m6.3 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.65 V · Corrosion Resistance 10 / 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 85 / 100 · Polishability 50 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 25 MJ/kg10,748 BTU/lb · Embodied Carbon (primary production) 1.9 kg CO₂/kg · Embodied Water 40 L/kg4.8 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.
C15E +A vs C15E +SR — frequently asked
Is C15E +SR stronger than C15E +A?
Yes. C15E +SR has a typical yield strength of 330 MPa (47.9 ksi) against 285 MPa (41.3 ksi) for C15E +A — about 16% more. Tensile strength is 410 MPa (59.5 ksi) vs 385 MPa (55.8 ksi).
Which condition does FabDigit quote by default, +A or +SR?
+N is the default C15E condition in the FabDigit quote flow (neither +A nor +SR). 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, C15E +A or C15E +SR?
C15E +SR, by a small margin. Both rate fair for machinability — 50/100 against 38/100 for C15E +A.
Ready to make it?
Upload a CAD file and FabDigit prices the part in C15E +A and C15E +SR 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.