Refractory Metal E635
EN E635
E635 is a Russian Zr-Sn-Nb-Fe alloy developed for structural components of VVER fuel assemblies, available as RXA, SRA, CWSR, CW and BQ+RXA.
Reference datasheet — E635 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 RXA condition
E635 tempers and conditions
E635 is supplied in 5 conditions, soft to hard. RXA is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
RXADefault Recrystallization annealed | Standard condition for sheet, strip and spacer-grid parts needing formability plus good irradiation stability. | 340 | 470 | 22 | 185 HB | — |
Β-quenched + recrystallization annealed | Beta-quench step refines and homogenises Nb/Fe second-phase particles for improved corrosion and irradiation-growth behaviour in structural parts. | 345 | 480 | 20 | 188 HB | 2.6 % IACS |
Stress-relief annealed | Pick when a formed or cold-worked part must keep most of its cold-work strength while relieving residual stress. | 490 | 600 | 13 | 20 HRC | 2.5 % IACS |
Cold worked and stress relieved | Highest-strength standard condition, used for guide tubes and channel tubing where creep/collapse resistance governs. | 540 | 640 | 11 | 23 HRC | 2.5 % IACS |
Cold worked | Intermediate mill condition; only used where maximum strength and no further forming is required. | 620 | 700 | 8 | 24 HRC | 2.5 % IACS |
What is E635?
E635 is a Russian Zr-Sn-Nb-Fe alloy developed for structural components of VVER fuel assemblies, available as RXA, SRA, CWSR, CW and BQ+RXA. It is used where dimensional stability under irradiation matters more than maximum ductility, providing 340 MPa yield, 470 MPa tensile, 22% elongation and 185 HB in grid strip, guide tube and channel forms. Practical limits are about 400 °C service, low machinability (30/100), moderate formability (60/100) and mandatory inert-gas or vacuum welding. E110 is the nearest alternative when cladding-grade corrosion behaviour is the priority. E635 has a density of 6.57 g/cm³ (0.237 lb/in³), lighter than 67% of refractory metal grades. It melts at 1,760°C (3,200 °F). E635 has a yield strength of 340 MPa (49.3 ksi) and a tensile strength of 470 MPa (68.2 ksi) — stronger than 53% of refractory metal grades. Elongation at break is 22% and the elastic modulus is 97 GPa (14.1 Msi).
What is E635 used for?
- VVER fuel assembly spacer grids
- guide tubes
- structural reactor components
Limitations
- Low stiffness — 97 GPa (14.1 Msi), worse than 91% of refractory metal grades
- Poor heat conductor — 14.5 W/m·K (8.38 BTU/hr·ft·°F), worse than 86% of refractory metal grades
- Low electrical conductivity — 2.6 % IACS, worse than 84% of refractory metal grades
E635 properties
Typical room-temperature values for E635-RXA; bars are the position among refractory metal grades.
Physical3
E635 has a density of 6.57 g/cm³ (0.237 lb/in³), lighter than 67% of refractory metal grades. It melts at 1,760°C (3,200 °F).
Mechanical16
E635 has a yield strength of 340 MPa (49.3 ksi) and a tensile strength of 470 MPa (68.2 ksi) — stronger than 53% of refractory metal grades. Elongation at break is 22% and the elastic modulus is 97 GPa (14.1 Msi).
Thermal6
E635 is rated for continuous service to 400°C (752 °F). It conducts heat at 14.5 W/m·K (8.38 BTU/hr·ft·°F), worse than 86% of refractory metal grades. Thermal expansion is 6 µm/m·K (3.33 µin/in·°F).
Electrical3
E635 conducts electricity at 2.6 % IACS, worse than 84% of refractory metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (86/100), better than 59% of refractory metal grades.
Sustainability4
Producing a kilogram of E635 takes about 1,400 MJ of energy and emits 90 kg of CO₂ — more than 67% of refractory metal grades. Typical recycled content is 10%.
Manufacturability8
E635's machinability is poor (30/100, better than 54% of refractory metal grades); weldability very good (70/100); formability good (60/100).
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. E635 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with E635
Is E635 easy to machine?
Machine slow with sharp, positive-rake carbide tools, heavy flood coolant and generous depth of cut to avoid galling and work-hardening; collect chips wet — dry fines are pyrophoric.
Can E635 be welded?
GTAW/EBW/laser only, with full argon or vacuum shielding of weld, root and hot zone; keep O/N/H pickup low, no flux, and stress-relieve after welding.
Can E635 be formed, bent or molded?
Form in the RXA condition; strong HCP texture means anisotropic springback, so bend across the rolling direction where possible and warm-form (200–350 °C) tight radii.
E635 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 |
|---|---|---|
| Snsolid-solution strengthener | 1.1 – 1.4 | 1.25 |
| Nbβ-Nb precipitates, corrosion/creep control | 0.9 – 1.1 | 1 |
| FeZr(Nb,Fe)2 Laves-type SPPs | 0.3 – 0.5 | 0.35 |
| Ocontrolled interstitial strengthener | 0.05 – 0.1 | 0.07 |
| Hfnuclear-grade limit (low neutron capture) | ≤ 0.05 | 0.01 |
| C | ≤ 0.02 | 0.01 |
| Si | ≤ 0.02 | 0.01 |
| N | ≤ 0.01 | 0 |
| Nirestricted to limit hydrogen pickup | ≤ 0.01 | |
| Zrbalance, nuclear-grade (Hf-free) sponge | balance |
What surface finishes work on E635?
Pickle in HNO3–HF then autoclave-passivate (400 °C steam) to build the protective black oxide; avoid iron contamination and abrasive smearing, no protective anodising or plating is standard.
How much does E635 cost?
E635 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.
E635 — frequently asked
What is E635 used for?
E635 is typically used for VVER fuel assembly spacer grids, guide tubes and structural reactor components. In short: structural-grade zirconium alloy; stable under irradiation growth; stronger than E110.
What is the yield strength of E635?
E635 has a typical yield strength of 340 MPa (49.3 ksi) and a tensile strength of 470 MPa (68.2 ksi) — stronger than 53% of refractory metal grades. Strength varies by condition: see the 5 listed tempers.
Is E635 easy to machine?
Not especially — machinability is rated poor (30/100, better than 54% of refractory metal grades). Machine slow with sharp, positive-rake carbide tools, heavy flood coolant and generous depth of cut to avoid galling and work-hardening; collect chips wet — dry fines are pyrophoric.
Can E635 be welded?
Yes — weldability is rated very good (70/100). GTAW/EBW/laser only, with full argon or vacuum shielding of weld, root and hot zone; keep O/N/H pickup low, no flux, and stress-relieve after welding.
What surface finishes work on E635?
Pickle in HNO3–HF then autoclave-passivate (400 °C steam) to build the protective black oxide; avoid iron contamination and abrasive smearing, no protective anodising or plating is standard.
Can E635 be formed, bent or molded?
Form in the RXA condition; strong HCP texture means anisotropic springback, so bend across the rolling direction where possible and warm-form (200–350 °C) tight radii.
What is the maximum service temperature of E635?
E635 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 E635-RXA and E635-CW?
RXA is the default condition — standard condition for sheet, strip and spacer-grid parts needing formability plus good irradiation stability. CW: intermediate mill condition; only used where maximum strength and no further forming is required. Yield strength is 340 MPa in RXA versus 620 MPa in CW.
How much does E635 cost?
E635 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
- Zirconium Alloys in Nuclear Power Engineering (Zaimovsky, Nikulina, Reshetnikov) — Energoatomizdat (1994)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys (Zirconium and Hafnium) — ASM International (1990)
- ASTM B350/B351 (Zr-alloy nuclear-grade sponge, bar, tube) — used for comparative property basis — ASTM International (2018)
- IAEA TECDOC-1410 / -996 — Waterside corrosion and behaviour of zirconium alloys (E110, E125, E635) — IAEA (2004)
- Chepetsky Mechanical Plant / TVEL zirconium alloy product information (E635) — Rosatom-TVEL (2020)
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.