Steel 4145-HR vs 4145 Q&T
Steel · 4145 temper comparison
4145-HR and 4145 Q&T are two conditions of the same steel grade, 4145: HR (hot rolled) 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 520 MPa (75.4 ksi) for 4145-HR, about 73% more; tensile strength follows at 1,080 MPa (157 ksi) vs 830 MPa (120 ksi). In exchange, 4145-HR is the more ductile: elongation 18% versus 16% for 4145 Q&T, and 4145 Q&T is harder (311 HB vs 235 HB).
4145-HRChoose it when the part is bent, formed or impact-loaded.
4145 Q&TChoose it when strength drives the design.
4145-HR 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
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell C
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 · Compressive Strength 540 MPa78.3 ksi · Shear Strength 500 MPa72.5 ksi · Hardness, Rockwell B 99 HRB · Hardness, Vickers 247 HV
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.
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 · Max Service Temperature (continuous) 400°C752 °F · 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 %)
Same in both: Weldability 35 / 100 · Formability (cold) 25 / 100 · 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-HR vs 4145 Q&T — frequently asked
Is 4145 Q&T stronger than 4145-HR?
Yes. 4145 Q&T has a typical yield strength of 900 MPa (131 ksi) against 520 MPa (75.4 ksi) for 4145-HR — about 73% more. Tensile strength is 1,080 MPa (157 ksi) vs 830 MPa (120 ksi).
Which condition does FabDigit quote by default, HR or Q&T?
HR is the default 4145 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.
Which is easier to machine, 4145-HR or 4145 Q&T?
4145-HR, by a small margin. Both rate fair for machinability — 50/100 against 45/100 for 4145 Q&T.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 4145-HR 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.