Refractory Metal E635 CWSR
Heat-treated state
EN E635
CWSR = cold worked and stress relieved
Highest-strength standard condition, used for guide tubes and channel tubing where creep/collapse resistance governs.
Values for the CWSR condition
Other E635 tempers and conditions
E635 is listed in 5 conditions; see the grade overview at E635.
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 |
CWSRThis page 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 CWSR?
E635 CWSR is E635 heat treated to CWSR — highest-strength standard condition, used for guide tubes and channel tubing where creep/collapse resistance governs. E635 CWSR has a yield strength of 540 MPa (78.3 ksi) and a tensile strength of 640 MPa (92.8 ksi) — stronger than 76% of refractory metal grades. Elongation at break is 11% and the elastic modulus is 98 GPa (14.2 Msi). E635 CWSR 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). RXA is the default condition FabDigit quotes; CWSR is available on request or by drawing note.
Advantages
- High strength — 540 MPa (78.3 ksi), better than 76% of refractory metal grades
Limitations
- Poor heat conductor — 14 W/m·K (8.09 BTU/hr·ft·°F), worse than 90% of refractory metal grades
- Limited service temperature — 360°C (680 °F), worse than 87% of refractory metal grades
- Low electrical conductivity — 2.5 % IACS, worse than 86% of refractory metal grades
- Low stiffness — 98 GPa (14.2 Msi), worse than 84% of refractory metal grades
E635 CWSR properties
Typical room-temperature values for E635 CWSR; 23 are specific to this condition. Other listed values are E635 reference data and may not represent this condition. Bars are the position among refractory metal grades.
Physical3
E635 CWSR 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 CWSR has a yield strength of 540 MPa (78.3 ksi) and a tensile strength of 640 MPa (92.8 ksi) — stronger than 76% of refractory metal grades. Elongation at break is 11% and the elastic modulus is 98 GPa (14.2 Msi).
Thermal6
E635 CWSR is rated for continuous service to 360°C (680 °F). It conducts heat at 14 W/m·K (8.09 BTU/hr·ft·°F), worse than 90% of refractory metal grades. Thermal expansion is 6 µm/m·K (3.33 µin/in·°F).
Electrical3
E635 CWSR conducts electricity at 2.5 % IACS, worse than 86% of refractory metal grades.
Chemical & Environmental3
Corrosion resistance is very good (84/100), worse than 53% of refractory metal grades.
Sustainability4
Producing a kilogram of E635 CWSR 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 CWSR's machinability is fair (35/100, better than 81% of refractory metal grades); weldability good (60/100); formability poor (30/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with E635 CWSR
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.
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.
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 | — |
E635 CWSR — frequently asked
What is E635 CWSR used for?
E635 CWSR 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 CWSR?
E635 CWSR has a typical yield strength of 540 MPa (78.3 ksi) and a tensile strength of 640 MPa (92.8 ksi) — stronger than 76% of refractory metal grades. Strength varies by condition: see the 5 listed tempers.
Is E635 CWSR easy to machine?
Not especially — machinability is rated fair (35/100, better than 81% 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 CWSR be welded?
Yes — weldability is rated good (60/100). 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 CWSR?
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 CWSR 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 CWSR?
E635 CWSR is rated for continuous use to about 360°C (680 °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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.