Steel 4340M-CR vs 4340M Q&T
Steel · 4340M temper comparison
4340M-CR and 4340M Q&T are two conditions of the same steel grade, 4340M: CR (cold rolled) versus Q&T (quenched and tempered). The chemistry is identical, so every difference below comes from the condition. 4340M Q&T is the stronger of the two: yield strength 1,620 MPa (235 ksi) against 830 MPa (120 ksi) for 4340M-CR, about 95% more; tensile strength follows at 1,930 MPa (280 ksi) vs 1,000 MPa (145 ksi). 4340M Q&T is the more ductile: elongation 10% versus 9% for 4340M-CR, and 4340M Q&T is harder (444 HB vs 293 HB). On the shop floor, 4340M-CR machines more easily (fair vs not recommended) and 4340M-CR welds better (poor vs not recommended).
4340M-CRChoose it when the part is machined in volume, or when it will be welded.
4340M Q&TChoose it when strength drives the design, or when the part is bent, formed or impact-loaded.
4340M-CR vs 4340M 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
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 205 GPa29.7 Msi · Shear Modulus 78 GPa11.3 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29
Physical
Density and transition temperatures.
Same in both: Density 7.83 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,420°C2,588 °F · Liquidus Temperature 1,480°C2,696 °F
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Same in both: Specific Heat Capacity 475 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 11.7 µm/m·K6.5 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Max Service Temperature (continuous) 290°C554 °F · Min Service Temperature -73°C-99 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 7 % IACS · Electrical Resistivity 2.4×10⁻⁷ Ω·m9.45 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.6 V · Corrosion Resistance 14 / 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 25 / 100 · Brazeability / Solderability 20 / 100 · Polishability 75 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 36 MJ/kg15,477 BTU/lb · Embodied Carbon (primary production) 2.6 kg CO₂/kg · Embodied Water 60 L/kg7.2 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.
4340M-CR vs 4340M Q&T — frequently asked
Is 4340M Q&T stronger than 4340M-CR?
Yes. 4340M Q&T has a typical yield strength of 1,620 MPa (235 ksi) against 830 MPa (120 ksi) for 4340M-CR — about 95% more. Tensile strength is 1,930 MPa (280 ksi) vs 1,000 MPa (145 ksi).
Which condition does FabDigit quote by default, CR or Q&T?
HR is the default 4340M condition in the FabDigit quote flow (neither CR 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, 4340M-CR or 4340M Q&T?
4340M-CR. Its machinability rates fair (36/100) against not recommended (12/100) for 4340M Q&T; for welding the order is 4340M-CR first (poor, 25/100) then 4340M Q&T (not recommended, 10/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 4340M-CR and 4340M 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.