Steel 4145-CD vs 4145 Q&T
Steel · 4145 temper comparison
4145-CD and 4145 Q&T are two conditions of the same steel grade, 4145: CD (cold drawn) versus Q&T (quenched and tempered). The chemistry is identical, so every difference below comes from the condition. 4145 Q&T is the stronger of the two: yield strength 900 MPa (131 ksi) against 700 MPa (102 ksi) for 4145-CD, about 29% more; tensile strength follows at 1,080 MPa (157 ksi) vs 830 MPa (120 ksi). 4145 Q&T is the more ductile: elongation 16% versus 12% for 4145-CD, and 4145 Q&T is harder (311 HB vs 248 HB). 4145 Q&T runs hotter in service (400°C vs 350°C continuous). On the shop floor, 4145-CD machines more easily (good vs fair).
4145-CDChoose it when the part is machined in volume.
4145 Q&TChoose it when strength drives the design, or when the part is bent, formed or impact-loaded.
4145-CD vs 4145 Q&T: 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
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell B
Hardness, Rockwell C
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 · Shear Strength 500 MPa72.5 ksi
Physical
Density and transition temperatures.
Same in both: Density 7.85 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,416°C2,581 °F · Liquidus Temperature 1,480°C2,696 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 43 W/m·K24.8 BTU/hr·ft·°F · Specific Heat Capacity 475 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 12.3 µm/m·K6.8 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Min Service Temperature -30°C-22 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 7.8 % IACS · Electrical Resistivity 2.2×10⁻⁷ Ω·m8.66 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.6 V · Corrosion Resistance 13 / 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: Castability 40 / 100 · Brazeability / Solderability 45 / 100 · Polishability 60 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 29 MJ/kg12,468 BTU/lb · Embodied Carbon (primary production) 2.3 kg CO₂/kg · Embodied Water 60 L/kg7.2 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.
4145-CD vs 4145 Q&T — frequently asked
Is 4145 Q&T stronger than 4145-CD?
Yes. 4145 Q&T has a typical yield strength of 900 MPa (131 ksi) against 700 MPa (102 ksi) for 4145-CD — about 29% more. Tensile strength is 1,080 MPa (157 ksi) vs 830 MPa (120 ksi).
Which condition does FabDigit quote by default, CD or Q&T?
HR is the default 4145 condition in the FabDigit quote flow (neither CD nor Q&T). 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, 4145-CD or 4145 Q&T?
4145-CD. Its machinability rates good (55/100) against fair (45/100) for 4145 Q&T; for welding the order is 4145 Q&T first (fair, 35/100) then 4145-CD (poor, 30/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 4145-CD and 4145 Q&T 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.