Refractory Metal Pure Nb As Rolled vs Pure Nb RRR300 Annealed
Refractory Metal · Pure Nb temper comparison
Pure Nb As Rolled and Pure Nb RRR300 Annealed are two conditions of the same refractory metal grade, Pure Nb: As Rolled (hot rolled) versus RRR300 Annealed (RRR ≥ 300, high-purity EB-melted and vacuum annealed). The chemistry is identical, so every difference below comes from the condition. Pure Nb As Rolled is the stronger of the two: yield strength 400 MPa (58 ksi) against 70 MPa (10.2 ksi) for Pure Nb RRR300 Annealed, about 5.7 times as much; tensile strength follows at 450 MPa (65.3 ksi) vs 180 MPa (26.1 ksi). In exchange, Pure Nb RRR300 Annealed is the more ductile: elongation 50% versus 10% for Pure Nb As Rolled, and Pure Nb As Rolled is harder (135 HB vs 48 HB). Pure Nb RRR300 Annealed runs hotter in service (400°C vs 300°C continuous). On the shop floor, Pure Nb As Rolled machines more easily (fair vs poor) and Pure Nb RRR300 Annealed welds better (excellent vs very good).
Pure Nb As RolledChoose it when strength drives the design, or when the part is machined in volume.
Pure Nb RRR300 AnnealedChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
Pure Nb As Rolled vs Pure Nb RRR300 Annealed: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all refractory metal 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 refractory metal 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.
Pure Nb As RolledPure Nb RRR300 Annealed
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Shear Strength
Fatigue Strength (Endurance Limit)
Hardness, Brinell
Hardness, Rockwell B
Hardness, Vickers
Same in both: Shear Modulus 37.5 GPa5.4 Msi · Bulk Modulus 170 GPa24.7 Msi · Poisson's Ratio 0.4
Physical
Density and transition temperatures.
Same in both: Density 8.57 g/cm³0.31 lb/in³ · Melting Point (Solidus) 2,477°C4,491 °F · Liquidus Temperature 2,477°C4,491 °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 265 J/kg·K0.06 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 7.3 µm/m·K4.1 µin/in·°F · Latent Heat of Fusion 290 J/g125 BTU/lb · Min Service Temperature -269°C-452 °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) -0.15 V
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Polishability
Same in both: Castability 20 / 100 · Brazeability / Solderability 60 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 500 MJ/kg214,962 BTU/lb · Embodied Carbon (primary production) 32 kg CO₂/kg · Embodied Water 400 L/kg47.9 gal/lb · Typical Recycled Content 25%
Strength versus weight
Yield strength against density for every refractory metal grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Pure Nb As Rolled vs Pure Nb RRR300 Annealed — frequently asked
Is Pure Nb As Rolled stronger than Pure Nb RRR300 Annealed?
Yes. Pure Nb As Rolled has a typical yield strength of 400 MPa (58 ksi) against 70 MPa (10.2 ksi) for Pure Nb RRR300 Annealed — about 5.7 times as much. Tensile strength is 450 MPa (65.3 ksi) vs 180 MPa (26.1 ksi).
Which condition does FabDigit quote by default, As Rolled or RRR300 Annealed?
Vacuum Annealed is the default Pure Nb condition in the FabDigit quote flow (neither As Rolled nor RRR300 Annealed). 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, Pure Nb As Rolled or Pure Nb RRR300 Annealed?
Pure Nb As Rolled. Its machinability rates fair (38/100) against poor (25/100) for Pure Nb RRR300 Annealed; for welding the order is Pure Nb RRR300 Annealed first (excellent, 85/100) then Pure Nb As Rolled (very good, 75/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in Pure Nb As Rolled and Pure Nb RRR300 Annealed 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.