Refractory Metal Excel
Excel is an AECL-developed Zr-Sn-Nb-Mo alloy created for CANDU pressure tubes, supplied as extruded (EXT), annealed, cold-worked, CWA and heat-treated (HT) material.
Reference datasheet — Excel is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the CW condition
Excel tempers and conditions
Excel is supplied in 4 conditions, soft to hard. CW is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Softest, most ductile and most corrosion-stable condition; chosen when formability or maximum toughness matters more than strength. | 470 | 620 | 22 | 205 HV | — |
CWDefault Cold worked | Standard CANDU pressure-tube condition: cold pilgered/drawn then stress-relieved ~400 °C for high strength with retained toughness. | 730 | 850 | 14 | 25 HRC | — |
Cold worked and aged | Ageing after cold work precipitates β/Mo-bearing phases for extra strength and creep resistance at some ductility cost. | 800 | 900 | 12 | 28 HRC | — |
Β-quenched and aged | Highest-strength and best creep-resistant condition for thin-wall pressure tubes; lowest fracture toughness and most sensitive to hydride embrittlement. | 870 | 990 | 10 | 31 HRC | — |
Supply forms, finishes and certifications
Ways Excel is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
EXT | Hot extruded | Supply form |
What is Excel?
Excel is an AECL-developed Zr-Sn-Nb-Mo alloy created for CANDU pressure tubes, supplied as extruded (EXT), annealed, cold-worked, CWA and heat-treated (HT) material. It is selected where zirconium-level neutron transparency must be combined with high strength and creep resistance, reaching 730 MPa yield, 850 MPa tensile, 14% elongation and 25 HRC, mainly in heavy-wall tube and pressure-boundary forms. The trade-offs are 400 °C service, poor machinability (28/100) and low formability (35/100), rapid work hardening, and loss of heat-treated strength in the weld HAZ. Zr-2.5Nb is the conventional pressure-tube alternative. Excel has a density of 6.57 g/cm³ (0.237 lb/in³), lighter than 67% of refractory metal grades. It melts at 1,780°C (3,236 °F). Excel has a yield strength of 730 MPa (106 ksi) and a tensile strength of 850 MPa (123 ksi) — stronger than 87% of refractory metal grades. Elongation at break is 14% and the elastic modulus is 97 GPa (14.1 Msi).
What is Excel used for?
- CANDU reactor pressure tubes
- Heavy-water reactor structural components
- Calandria and channel hardware
- High-strength zirconium tubing
- Reactor pressure-boundary fittings
Advantages
- High strength — 730 MPa (106 ksi), better than 87% of refractory metal grades
Limitations
- Low stiffness — 97 GPa (14.1 Msi), worse than 91% of refractory metal grades
- Low electrical conductivity — 2.2 % IACS, worse than 91% of refractory metal grades
- Poor heat conductor — 15.5 W/m·K (8.96 BTU/hr·ft·°F), worse than 81% of refractory metal grades
Excel properties
Typical room-temperature values for Excel-CW; bars are the position among refractory metal grades.
Physical3
Excel has a density of 6.57 g/cm³ (0.237 lb/in³), lighter than 67% of refractory metal grades. It melts at 1,780°C (3,236 °F).
Mechanical13
Excel has a yield strength of 730 MPa (106 ksi) and a tensile strength of 850 MPa (123 ksi) — stronger than 87% of refractory metal grades. Elongation at break is 14% and the elastic modulus is 97 GPa (14.1 Msi).
Thermal6
Excel is rated for continuous service to 400°C (752 °F). It conducts heat at 15.5 W/m·K (8.96 BTU/hr·ft·°F), worse than 81% of refractory metal grades. Thermal expansion is 6 µm/m·K (3.33 µin/in·°F).
Electrical3
Excel conducts electricity at 2.2 % IACS, worse than 91% of refractory metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (85/100), better than 52% of refractory metal grades.
Sustainability4
Producing a kilogram of Excel takes about 1,400 MJ of energy and emits 85 kg of CO₂ — more than 67% of refractory metal grades. Typical recycled content is 15%.
Manufacturability8
Excel's machinability is poor (28/100, worse than 58% of refractory metal grades); weldability fair (45/100); formability fair (35/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the refractory metal family
Yield strength against density for every refractory metal grade FabDigit runs. Excel is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Excel
Is Excel easy to machine?
Slow speeds, heavy positive-rake carbide tooling and flood coolant; fine chips are pyrophoric and must be collected wet.
Can Excel be welded?
GTAW/EBW in high-purity argon or vacuum only — any air, N or H pickup embrittles the weld; heat-treated strength is lost in the HAZ and cannot be restored without full re-solution treatment.
Can Excel be formed, bent or molded?
Cold pilgering and tube drawing are feasible but the alloy work-hardens rapidly, needing intermediate vacuum anneals; hot working done in the α+β range around 800 °C.
Excel chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Snprimary solid-solution strengthener | 3.2 – 3.8 | 3.5 |
| Nbβ-stabiliser | 0.6 – 1 | 0.8 |
| Moβ-stabiliser, creep resistance | 0.6 – 1 | 0.8 |
| Ocontrolled interstitial (900–1300 ppm) | 0.09 – 0.13 | 0.11 |
| Feresidual | ≤ 0.05 | 0.03 |
| Cresidual | ≤ 0.03 | 0.02 |
| Nresidual | ≤ 0.01 | 0 |
| Hfnuclear-grade limit | ≤ 0.01 | 0.01 |
| Zr | balance |
What surface finishes work on Excel?
Pickle in HNO3/HF to remove oxide and hydride-rich surface, then autoclave-passivate in steam; anodising gives decorative/identification oxide films only.
Equivalent designations
Standards and trade names that resolve to Refractory Metal Excel in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Also called
- Zr-3.5Sn-0.8Nb-0.8Mo
How much does Excel cost?
Excel is a high-cost refractory metal ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Excel — frequently asked
What is Excel used for?
Excel is typically used for CANDU reactor pressure tubes, heavy-water reactor structural components, calandria and channel hardware, high-strength zirconium tubing and reactor pressure-boundary fittings. In short: strongest zirconium pressure-tube alloy; high creep resistance; heat-treatable Zr-Sn-Nb-Mo.
What is the yield strength of Excel?
Excel has a typical yield strength of 730 MPa (106 ksi) and a tensile strength of 850 MPa (123 ksi) — stronger than 87% of refractory metal grades. Strength varies by condition: see the 4 listed tempers.
Is Excel easy to machine?
Not especially — machinability is rated poor (28/100, worse than 58% of refractory metal grades). Slow speeds, heavy positive-rake carbide tooling and flood coolant; fine chips are pyrophoric and must be collected wet.
Can Excel be welded?
With care — weldability is rated fair (45/100). GTAW/EBW in high-purity argon or vacuum only — any air, N or H pickup embrittles the weld; heat-treated strength is lost in the HAZ and cannot be restored without full re-solution treatment.
What surface finishes work on Excel?
Pickle in HNO3/HF to remove oxide and hydride-rich surface, then autoclave-passivate in steam; anodising gives decorative/identification oxide films only.
Can Excel be formed, bent or molded?
Cold pilgering and tube drawing are feasible but the alloy work-hardens rapidly, needing intermediate vacuum anneals; hot working done in the α+β range around 800 °C.
What is the maximum service temperature of Excel?
Excel is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Excel-CW and Excel-ANN?
CW is the default condition — standard CANDU pressure-tube condition: cold pilgered/drawn then stress-relieved ~400 °C for high strength with retained toughness. ANN: softest, most ductile and most corrosion-stable condition; chosen when formability or maximum toughness matters more than strength. Yield strength is 730 MPa in CW versus 470 MPa in ANN.
How much does Excel cost?
Excel is a high-cost refractory metal ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys (Zirconium and Zirconium Alloys) — ASM International (1990)
- ASM Handbook Vol.13B — Corrosion: Materials (Zirconium) — ASM International (2005)
- ASTM B353 / B811 — Wrought zirconium and zirconium alloy tubing for nuclear service — ASTM International (2018)
- AECL CANDU pressure-tube alloy development literature (Excel Zr-3.5Sn-0.8Nb-0.8Mo) — Atomic Energy of Canada Limited (1990)
- IAEA TECDOC on zirconium alloy properties for water reactor fuel and pressure tubes — IAEA (2010)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.