Steel C15R +A vs C15R +U
Steel · C15R temper comparison
C15R +A and C15R +U are two conditions of the same steel grade, C15R: +A (annealed) versus +U (hot rolled). The chemistry is identical, so every difference below comes from the condition. C15R +U is the stronger of the two: yield strength 280 MPa (40.6 ksi) against 250 MPa (36.3 ksi) for C15R +A, about 12% more; tensile strength follows at 460 MPa (66.7 ksi) vs 420 MPa (60.9 ksi). In exchange, C15R +A is the more ductile: elongation 30% versus 26% for C15R +U, and C15R +U is harder (135 HB vs 125 HB).
C15R +AChoose it when the part is bent, formed or impact-loaded.
C15R +UChoose it when strength drives the design.
C15R +A vs C15R +U: 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.
Same in both: Thermal Conductivity 50 W/m·K28.9 BTU/hr·ft·°F · Specific Heat Capacity 470 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 11.8 µm/m·K6.6 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Max Service Temperature (continuous) 400°C752 °F · Min Service Temperature -20°C-4 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 10.5 % 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 %)
Formability (cold)
Same in both: Weldability 92 / 100 · Brazeability / Solderability 80 / 100 · Polishability 45 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 25 MJ/kg10,748 BTU/lb · Embodied Carbon (primary production) 2.1 kg CO₂/kg · Embodied Water 45 L/kg5.4 gal/lb · Typical Recycled Content 25%
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.
C15R +A vs C15R +U — frequently asked
Is C15R +U stronger than C15R +A?
Yes. C15R +U has a typical yield strength of 280 MPa (40.6 ksi) against 250 MPa (36.3 ksi) for C15R +A — about 12% more. Tensile strength is 460 MPa (66.7 ksi) vs 420 MPa (60.9 ksi).
Which condition does FabDigit quote by default, +A or +U?
+A is the default C15R 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.
When should I choose C15R +A over C15R +U?
Pick C15R +A when the part is bent, formed or impact-loaded. Pick C15R +U when strength drives the design.
Ready to make it?
Upload a CAD file and FabDigit prices the part in C15R +A and C15R +U 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.