Refractory Metal S-65 SR-Anneal
Heat-treated state
ASTM B349 Grade S-65
Applied to machined optical and metrology parts to remove machining stresses and maximise long-term dimensional stability.
Values for the SR-Anneal condition
Other S-65 tempers and conditions
S-65 is listed in 3 conditions; see the grade overview at S-65.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SR-AnnealThis page Stress-relieved / annealed (≈730–790 °C, vacuum) | Applied to machined optical and metrology parts to remove machining stresses and maximise long-term dimensional stability. | 205 | 320 | 5.5 | 108 HB | 41 % IACS |
Hot isostatic pressed | Choose for near-net shapes and the most isotropic properties in thick sections. | 240 | 365 | 5 | 120 HB | 40 % IACS |
Extruded bar / tube | Use where high longitudinal strength and stiffness in a slender section are needed (struts, tubes). | 330 | 460 | 8 | 132 HB | 39 % IACS |
What is S-65 SR-Anneal?
S-65 SR-Anneal is S-65 heat treated to SR-Anneal — applied to machined optical and metrology parts to remove machining stresses and maximise long-term dimensional stability. S-65 SR-Anneal has a yield strength of 205 MPa (29.7 ksi) and a tensile strength of 320 MPa (46.4 ksi) — weaker than 84% of refractory metal grades. Elongation at break is 5.5% and the elastic modulus is 303 GPa (43.9 Msi). S-65 SR-Anneal has a density of 1.85 g/cm³ (0.0668 lb/in³), lighter than 96% of refractory metal grades. It melts at 1,287°C (2,349 °F).
Advantages
- Easy to machine — 48/100, better than 101% of refractory metal grades
- Conducts heat well — 215 W/m·K (124.2 BTU/hr·ft·°F), better than 99% of refractory metal grades
- Lightweight — 1.85 g/cm³ (0.0668 lb/in³), better than 96% of refractory metal grades
- High electrical conductivity — 41 % IACS, better than 96% of refractory metal grades
Limitations
- High embodied carbon — 250 kg CO₂/kg, worse than 89% of refractory metal grades
- Needs corrosion protection — 45/100, worse than 86% of refractory metal grades
- Low strength — 205 MPa (29.7 ksi), worse than 84% of refractory metal grades
- Limited ductility — 5.5%, worse than 78% of refractory metal grades
- Low fracture toughness — 14 MPa·√m (12.7 ksi·√in), worse than 78% of refractory metal grades
S-65 SR-Anneal properties
Typical room-temperature values for S-65 SR-Anneal; 21 are specific to this condition. Other listed values are S-65 reference data and may not represent this condition. Bars are the position among refractory metal grades.
Physical3
S-65 SR-Anneal has a density of 1.85 g/cm³ (0.0668 lb/in³), lighter than 96% of refractory metal grades. It melts at 1,287°C (2,349 °F).
Mechanical13
S-65 SR-Anneal has a yield strength of 205 MPa (29.7 ksi) and a tensile strength of 320 MPa (46.4 ksi) — weaker than 84% of refractory metal grades. Elongation at break is 5.5% and the elastic modulus is 303 GPa (43.9 Msi).
Thermal6
S-65 SR-Anneal is rated for continuous service to 500°C (932 °F). It conducts heat at 215 W/m·K (124.2 BTU/hr·ft·°F), better than 99% of refractory metal grades. Thermal expansion is 11.3 µm/m·K (6.28 µin/in·°F).
Electrical3
S-65 SR-Anneal conducts electricity at 41 % IACS, better than 96% of refractory metal grades.
Chemical & Environmental3
Corrosion resistance is fair (45/100), worse than 86% of refractory metal grades.
Sustainability4
Producing a kilogram of S-65 SR-Anneal takes about 4,000 MJ of energy and emits 250 kg of CO₂ — more than 89% of refractory metal grades. Typical recycled content is 15%.
Manufacturability8
S-65 SR-Anneal's machinability is fair (48/100, better than 101% of refractory metal grades); weldability poor (22/100); formability poor (18/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with S-65 SR-Anneal
Is S-65 easy to machine?
Machines like a hard, abrasive cast iron with carbide/PCD tooling and low feeds; all dust and coolant must be captured (Be sensitisation/CBD hazard), and a light chemical etch removes the damaged twinned surface layer.
Can S-65 be welded?
Fusion welding is difficult (hot cracking, coarse grain); electron-beam welding with Al-Si filler, Ag-based brazing or mechanical/adhesive joining are preferred.
Can S-65 be formed, bent or molded?
Cold formability is essentially nil due to the hcp structure; forming, bending and deep drawing are done warm (400–800 °C), often with steel cladding.
What surface finishes work on S-65?
Not anodizable in the aluminium sense — use chromate conversion coating, electroless nickel or Ni plating; optical surfaces are diamond-turned/polished after etching and often nickel-plated.
S-65 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 |
|---|---|---|
| BeOberyllium oxide content, low-oxide grade | ≤ 1 | 0.7 |
| Fe | ≤ 0.08 | 0.05 |
| C | ≤ 0.1 | 0.06 |
| Al | ≤ 0.06 | 0.03 |
| Mg | ≤ 0.06 | 0.02 |
| Si | ≤ 0.06 | 0.02 |
| other metallic impurities (each)per element | ≤ 0.04 | — |
| Beassay, minimum | ≥ 99 (balance) | — |
S-65 SR-Anneal — frequently asked
What is S-65 SR-Anneal used for?
S-65 SR-Anneal is typically used for precision optical mirrors, space telescope structures and high-reliability aerospace brackets. In short: most ductile beryllium grade; very low BeO content; aerospace-standard Be grade.
What is the yield strength of S-65 SR-Anneal?
S-65 SR-Anneal has a typical yield strength of 205 MPa (29.7 ksi) and a tensile strength of 320 MPa (46.4 ksi) — weaker than 84% of refractory metal grades. Strength varies by condition: see the 3 listed tempers.
Is S-65 SR-Anneal easy to machine?
Reasonably — machinability is rated fair (48/100, better than 101% of refractory metal grades). Machines like a hard, abrasive cast iron with carbide/PCD tooling and low feeds; all dust and coolant must be captured (Be sensitisation/CBD hazard), and a light chemical etch removes the damaged twinned surface layer.
Can S-65 SR-Anneal be welded?
Not readily — weldability is rated poor (22/100). Fusion welding is difficult (hot cracking, coarse grain); electron-beam welding with Al-Si filler, Ag-based brazing or mechanical/adhesive joining are preferred.
What surface finishes work on S-65 SR-Anneal?
Not anodizable in the aluminium sense — use chromate conversion coating, electroless nickel or Ni plating; optical surfaces are diamond-turned/polished after etching and often nickel-plated.
Can S-65 SR-Anneal be formed, bent or molded?
Cold formability is essentially nil due to the hcp structure; forming, bending and deep drawing are done warm (400–800 °C), often with steel cladding.
What is the maximum service temperature of S-65 SR-Anneal?
S-65 SR-Anneal is rated for continuous use to about 500°C (932 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASTM B349/B349M — Beryllium grades (S-65 chemistry and mechanical requirements) — ASTM International (2020)
- Structural beryllium grades S-65 / S-200F product data — Materion Beryllium & Composites (2023)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys (Beryllium) — ASM International (1990)
- Beryllium: Chemistry, Metallurgy and Applications — technical literature (2009)
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.