Steel C45EC +H vs C45EC +U
Steel · C45EC temper comparison
C45EC +H and C45EC +U are two conditions of the same steel grade, C45EC: +H (guaranteed hardenability (Jominy band), hardened and tempered condition) versus +U (hot rolled). The chemistry is identical, so every difference below comes from the condition. C45EC +H is the stronger of the two: yield strength 620 MPa (89.9 ksi) against 400 MPa (58 ksi) for C45EC +U, about 55% more; tensile strength follows at 850 MPa (123 ksi) vs 700 MPa (102 ksi). C45EC +H is harder — 250 HB against 200 HB for C45EC +U — which matters for wear surfaces and threads. C45EC +H runs hotter in service (400°C vs 300°C continuous). On the shop floor, C45EC +U welds better (fair vs poor) and C45EC +U forms better (fair vs poor).
C45EC +HChoose it when strength drives the design, or when surface hardness matters.
C45EC +UChoose it when it will be welded.
C45EC +H vs C45EC +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
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 208 GPa30.2 Msi · Shear Modulus 80 GPa11.6 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Compressive Strength 630 MPa91.4 ksi
Physical
Density and transition temperatures.
Same in both: Density 7.85 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,420°C2,588 °F · Liquidus Temperature 1,490°C2,714 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 48 W/m·K27.7 BTU/hr·ft·°F · Specific Heat Capacity 480 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 11.6 µm/m·K6.4 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Min Service Temperature -20°C-4 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 10 % IACS · Electrical Resistivity 1.7×10⁻⁷ Ω·m6.69 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.61 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 65 / 100 · Polishability 60 / 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 45 L/kg5.4 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.
C45EC +H vs C45EC +U — frequently asked
Is C45EC +H stronger than C45EC +U?
Yes. C45EC +H has a typical yield strength of 620 MPa (89.9 ksi) against 400 MPa (58 ksi) for C45EC +U — about 55% more. Tensile strength is 850 MPa (123 ksi) vs 700 MPa (102 ksi).
Which condition does FabDigit quote by default, +H or +U?
+AC+C is the default C45EC condition in the FabDigit quote flow (neither +H nor +U). 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, C45EC +H or C45EC +U?
C45EC +U, by a small margin. Both rate fair for machinability — 50/100 against 45/100 for C45EC +H; for welding the order is C45EC +U first (fair, 40/100) then C45EC +H (poor, 30/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in C45EC +H and C45EC +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.