Steel 15B21-CR vs 15B21-HR
Steel · 15B21 temper comparison
15B21-CR and 15B21-HR are two conditions of the same steel grade, 15B21: CR (cold rolled) versus HR (hot rolled). The chemistry is identical, so every difference below comes from the condition. 15B21-CR is the stronger of the two: yield strength 440 MPa (63.8 ksi) against 280 MPa (40.6 ksi) for 15B21-HR, about 57% more; tensile strength follows at 520 MPa (75.4 ksi) vs 450 MPa (65.3 ksi). In exchange, 15B21-HR is the more ductile: elongation 28% versus 14% for 15B21-CR, and 15B21-CR is harder (155 HB vs 131 HB).
15B21-CRChoose it when strength drives the design.
15B21-HRChoose it when the part is bent, formed or impact-loaded.
15B21-CR vs 15B21-HR: 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)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell B
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 300 MPa43.5 ksi
Physical
Density and transition temperatures.
Same in both: Density 7.85 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,425°C2,597 °F · Liquidus Temperature 1,515°C2,759 °F
Thermal
How each material carries heat and how hot it can run.
Same in both: Thermal Conductivity 51 W/m·K29.5 BTU/hr·ft·°F · 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 270 J/g116 BTU/lb · Max Service Temperature (continuous) 400°C752 °F · 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 Rating (AISI 1212 = 100 %)
Formability (cold)
Same in both: Machinability 55 / 100 · Weldability 85 / 100 · Brazeability / Solderability 75 / 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 30 L/kg3.6 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.
15B21-CR vs 15B21-HR — frequently asked
Is 15B21-CR stronger than 15B21-HR?
Yes. 15B21-CR has a typical yield strength of 440 MPa (63.8 ksi) against 280 MPa (40.6 ksi) for 15B21-HR — about 57% more. Tensile strength is 520 MPa (75.4 ksi) vs 450 MPa (65.3 ksi).
Which condition does FabDigit quote by default, CR or HR?
HR is the default 15B21 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.
When should I choose 15B21-CR over 15B21-HR?
Pick 15B21-CR when strength drives the design. Pick 15B21-HR when the part is bent, formed or impact-loaded.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 15B21-CR and 15B21-HR 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.