Steel 9SMnPb28-CH vs 9SMnPb28 +U
Steel · 9SMnPb28 temper comparison
9SMnPb28-CH and 9SMnPb28 +U are two conditions of the same steel grade, 9SMnPb28: CH (carburized and hardened) versus +U (hot rolled). The chemistry is identical, so every difference below comes from the condition. 9SMnPb28-CH is the stronger of the two: yield strength 330 MPa (47.9 ksi) against 260 MPa (37.7 ksi) for 9SMnPb28 +U, about 27% more; tensile strength follows at 500 MPa (72.5 ksi) vs 430 MPa (62.4 ksi). In exchange, 9SMnPb28 +U is the more ductile: elongation 22% versus 10% for 9SMnPb28-CH, and 9SMnPb28-CH is harder (175 HB vs 130 HB). 9SMnPb28 +U runs hotter in service (250°C vs 200°C continuous). On the shop floor, 9SMnPb28 +U machines more easily (excellent vs poor).
9SMnPb28-CHChoose it when strength drives the design.
9SMnPb28 +UChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
9SMnPb28-CH vs 9SMnPb28 +U: 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
Shear Strength
Fatigue Strength (Endurance Limit)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell B
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
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 1,510°C2,750 °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) 11.5 µm/m·K6.4 µin/in·°F · Latent Heat of Fusion 247 J/g106 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).
Corrosion Resistance
Same in both: Galvanic Potential (seawater, vs SCE) -0.61 V
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 40 / 100 · Polishability 45 / 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 40 L/kg4.8 gal/lb · Typical Recycled Content 40%
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.
9SMnPb28-CH vs 9SMnPb28 +U — frequently asked
Is 9SMnPb28-CH stronger than 9SMnPb28 +U?
Yes. 9SMnPb28-CH has a typical yield strength of 330 MPa (47.9 ksi) against 260 MPa (37.7 ksi) for 9SMnPb28 +U — about 27% more. Tensile strength is 500 MPa (72.5 ksi) vs 430 MPa (62.4 ksi).
Which condition does FabDigit quote by default, CH or +U?
+C is the default 9SMnPb28 condition in the FabDigit quote flow (neither CH nor +U). 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, 9SMnPb28-CH or 9SMnPb28 +U?
9SMnPb28 +U. Its machinability rates excellent (85/100) against poor (25/100) for 9SMnPb28-CH; for welding the order is 9SMnPb28 +U first (not recommended, 10/100) then 9SMnPb28-CH (not recommended, 3/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 9SMnPb28-CH and 9SMnPb28 +U 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.