Steel P91 Annealed vs P91-HR
Steel · P91 temper comparison
P91 Annealed and P91-HR are two conditions of the same steel grade, P91: Annealed versus HR (hot rolled). The chemistry is identical, so every difference below comes from the condition. P91-HR is the stronger of the two: yield strength 750 MPa (109 ksi) against 350 MPa (50.8 ksi) for P91 Annealed, about 114% more; tensile strength follows at 1,000 MPa (145 ksi) vs 560 MPa (81.2 ksi). In exchange, P91 Annealed is the more ductile: elongation 28% versus 14% for P91-HR, and P91-HR is harder (330 HB vs 180 HB). P91 Annealed runs hotter in service (450°C vs 200°C continuous). On the shop floor, P91 Annealed machines more easily (fair vs poor).
P91 AnnealedChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
P91-HRChoose it when strength drives the design.
P91 Annealed vs P91-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
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell B
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 218 GPa31.6 Msi · Shear Modulus 84 GPa12.2 Msi · Bulk Modulus 170 GPa24.7 Msi · Poisson's Ratio 0.3 · Compressive Strength 770 MPa112 ksi · Shear Strength 600 MPa87 ksi · Fatigue Strength (Endurance Limit) 430 MPa62.4 ksi · Fracture Toughness (K_IC) 40 MPa·√m36.4 ksi·√in · Hardness, Rockwell C 35 HRC
Physical
Density and transition temperatures.
Same in both: Density 7.77 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,450°C2,642 °F · Liquidus Temperature 1,500°C2,732 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 25 W/m·K14.4 BTU/hr·ft·°F · Specific Heat Capacity 480 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 10.9 µm/m·K6.1 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Min Service Temperature -30°C-22 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 2.7 % IACS · Electrical Resistivity 6.4×10⁻⁷ Ω·m25.2 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Corrosion Resistance 28 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Formability (cold)
Same in both: Machinability Rating (AISI 1212 = 100 %) 25% · Weldability 15 / 100 · Brazeability / Solderability 30 / 100 · Polishability 55 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 34 MJ/kg14,617 BTU/lb · Embodied Carbon (primary production) 2.5 kg CO₂/kg · Embodied Water 70 L/kg8.4 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.
P91 Annealed vs P91-HR — frequently asked
Is P91-HR stronger than P91 Annealed?
Yes. P91-HR has a typical yield strength of 750 MPa (109 ksi) against 350 MPa (50.8 ksi) for P91 Annealed — about 114% more. Tensile strength is 1,000 MPa (145 ksi) vs 560 MPa (81.2 ksi).
Which condition does FabDigit quote by default, Annealed or HR?
HR is the default P91 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, P91 Annealed or P91-HR?
P91 Annealed. Its machinability rates fair (50/100) against poor (22/100) for P91-HR.
Ready to make it?
Upload a CAD file and FabDigit prices the part in P91 Annealed and P91-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.