Steel 10B38-HR vs 10B38 Q&T 40-45 HRC
Steel · 10B38 temper comparison
10B38-HR and 10B38 Q&T 40-45 HRC are two conditions of the same steel grade, 10B38: HR (hot rolled) versus Q&T 40-45 HRC (quenched and low-tempered). The chemistry is identical, so every difference below comes from the condition. 10B38 Q&T 40-45 HRC is the stronger of the two: yield strength 1,180 MPa (171 ksi) against 320 MPa (46.4 ksi) for 10B38-HR, about 3.7 times as much; tensile strength follows at 1,350 MPa (196 ksi) vs 570 MPa (82.7 ksi). In exchange, 10B38-HR is the more ductile: elongation 20% versus 10% for 10B38 Q&T 40-45 HRC, and 10B38 Q&T 40-45 HRC is harder (400 HB vs 163 HB). 10B38-HR runs hotter in service (400°C vs 250°C continuous) and 10B38-HR conducts heat better (49 W/m·K vs 44 W/m·K). On the shop floor, 10B38-HR machines more easily (good vs poor) and 10B38-HR welds better (good vs poor).
10B38-HRChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
10B38 Q&T 40-45 HRCChoose it when strength drives the design.
10B38-HR vs 10B38 Q&T 40-45 HRC: 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)
Charpy V-Notch Impact (RT)
Hardness, Brinell
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 · Hardness, Rockwell B 85 HRB
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 1,500°C2,732 °F
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Max Service Temperature (continuous)
Same in both: Specific Heat Capacity 470 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 260 J/g112 BTU/lb · Min Service Temperature -20°C-4 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
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 55 / 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 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.
10B38-HR vs 10B38 Q&T 40-45 HRC — frequently asked
Is 10B38 Q&T 40-45 HRC stronger than 10B38-HR?
Yes. 10B38 Q&T 40-45 HRC has a typical yield strength of 1,180 MPa (171 ksi) against 320 MPa (46.4 ksi) for 10B38-HR — about 3.7 times as much. Tensile strength is 1,350 MPa (196 ksi) vs 570 MPa (82.7 ksi).
Which condition does FabDigit quote by default, HR or Q&T 40-45 HRC?
HR is the default 10B38 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, 10B38-HR or 10B38 Q&T 40-45 HRC?
10B38-HR. Its machinability rates good (58/100) against poor (30/100) for 10B38 Q&T 40-45 HRC; for welding the order is 10B38-HR first (good, 55/100) then 10B38 Q&T 40-45 HRC (poor, 25/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 10B38-HR and 10B38 Q&T 40-45 HRC 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.