Refractory Metal Pure Nb vs R04251
Refractory Metal · grade comparison
Refractory Metal Pure Nb and R04251 are both refractory metal grades. R04251 is the stronger of the two: yield strength 140 MPa (20.3 ksi) against 125 MPa (18.1 ksi) for Pure Nb, about 12% more; tensile strength follows at 250 MPa (36.3 ksi) vs 220 MPa (31.9 ksi). In exchange, Pure Nb is the more ductile: elongation 40% versus 30% for R04251, and R04251 is harder (100 HV vs 80 HV). Pure Nb conducts heat better (53.7 W/m·K vs 45 W/m·K). On the shop floor, R04251 sits in a lower cost tier (high, $$$$) than Pure Nb (specialty, $$$$$).
Pure NbChoose it when the part is bent, formed or impact-loaded.
R04251Choose it when strength drives the design, or when cost is the deciding factor.
Pure Nb vs R04251: 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.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Shear Modulus
Poisson's Ratio
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Shear Strength
Fatigue Strength (Endurance Limit)
Hardness, Brinell
Hardness, Rockwell B
Hardness, Vickers
Same in both: Bulk Modulus 170 GPa24.7 Msi · Reduction in Area 80%
Physical
Density and transition temperatures.
Density
Melting Point (Solidus)
Liquidus Temperature
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Latent Heat of Fusion
Min Service Temperature
Same in both: Max Service Temperature (continuous) 400°C752 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Galvanic Potential (seawater, vs SCE)
Corrosion Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Formability (cold)
Polishability
Same in both: Machinability 28 / 100 · Machinability Rating (AISI 1212 = 100 %) 25% · Weldability 80 / 100 · Castability 20 / 100 · Brazeability / Solderability 60 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Typical Recycled Content
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Modulus of Resilience
Thermal Diffusivity
Same in both: Thermal Shock Resistance Index 16
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.
Manufacturing and finishing
| Capability | Pure Nb | R04251 |
|---|---|---|
| Default condition | Vacuum Annealed | — |
| Relative cost | $$$$$ Specialty | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Pure Nb vs R04251 — frequently asked
Is R04251 stronger than Pure Nb?
Yes. R04251 has a typical yield strength of 140 MPa (20.3 ksi) against 125 MPa (18.1 ksi) for Pure Nb — about 12% more. Tensile strength is 250 MPa (36.3 ksi) vs 220 MPa (31.9 ksi).
Which is cheaper, Pure Nb or R04251?
R04251 is the lower-cost material: it sits in the high tier ($$$$) while Pure Nb is specialty ($$$$$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.
When should I choose Pure Nb over R04251?
Pick Pure Nb when the part is bent, formed or impact-loaded. Pick R04251 when strength drives the design, or when cost is the deciding factor.
Ready to make it?
Upload a CAD file and FabDigit prices the part in Pure Nb and R04251 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.