Copper Alloy Cu-OF-OS025
Temper
UNS C10200 · EN CR008A · JIS C1020 · GB TU1
OS025 = annealed to 0.025 mm grain size
Fine-grain soft strip for deep drawing with good surface finish.
Values for the OS025 condition
Other Cu-OF tempers and conditions
Cu-OF is listed in 14 conditions; see the grade overview at Cu-OF.
Compare all 14 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed to 0.050 mm grain size | Coarse-grain soft temper for maximum drawability and lowest springback. | 69 | 220 | 48 | 42 HB | 101 % IACS |
Soft annealed | Wrought benchmark condition: maximum conductivity and formability, minimum strength. | 70 | 225 | 45 | 45 HB | 101 % IACS |
As hot rolled | Mill condition of hot-worked plate and extrusion, essentially soft with mill surface. | 70 | 215 | 45 | 45 HB | 101 % IACS |
Binder Jetted + Sintered | Lowest-cost route for complex heat-sink geometries; 95–99 % density leaves some loss of strength and conductivity. | 75 | 175 | 25 | 45 HB | 88 % IACS |
OS025This page Annealed to 0.025 mm grain size | Fine-grain soft strip for deep drawing with good surface finish. | 85 | 235 | 42 | 48 HB | 101 % IACS |
EB-PBF As-Built | Vacuum EB melting gives near-full density and >97 % IACS as-built; best route for large conductive parts. | 95 | 200 | 45 | 52 HB | 98 % IACS |
1/8 hard | Light cold work when slightly higher stiffness than soft is needed but forming is still required. | 165 | 240 | 35 | 60 HB | 101 % IACS |
Quarter hard | Standard bendable temper for busbar and terminals needing some stiffness. | 195 | 260 | 30 | 68 HB | 101 % IACS |
Half hard | Most-stocked cold-worked temper for busbar, terminals and machined fittings. | 250 | 285 | 14 | 80 HB | 100 % IACS |
Hard drawn | As-drawn tube temper for rigid conductive tubing and waveguide bodies. | 250 | 290 | 15 | 85 HB | 100 % IACS |
Full hard | Hard temper for straight bar, hard-drawn wire and contacts where strength and machining behaviour matter. | 300 | 325 | 8 | 92 HB | 100 % IACS |
Extra hard | Higher cold work for thin strip and wire where formability is no longer needed. | 320 | 345 | 6 | 96 HB | 99 % IACS |
Spring hard | Spring-hard strip/wire for contacts and gaskets requiring elastic stiffness. | 340 | 365 | 4 | 100 HB | 99 % IACS |
Extra spring hard | Maximum-strength cold-drawn wire/strip; essentially no formability left. | 370 | 395 | 3 | 105 HB | 98 % IACS |
What is Cu-OF-OS025?
Cu-OF-OS025 is Cu-OF in the OS025 temper — fine-grain soft strip for deep drawing with good surface finish. Cu-OF-OS025 has a yield strength of 85 MPa (12.3 ksi) and a tensile strength of 235 MPa (34.1 ksi) — weaker than 89% of copper alloy grades. Elongation at break is 42% and the elastic modulus is 115 GPa (16.7 Msi). Cu-OF-OS025 has a density of 8.94 g/cm³ (0.323 lb/in³), heavier than 90% of copper alloy grades. It melts at 1,083°C (1,981 °F).
Advantages
- Tough — resists crack growth — 95 MPa·√m (86.5 ksi·√in), better than 100% of copper alloy grades
- Conducts heat well — 391 W/m·K (225.9 BTU/hr·ft·°F), better than 98% of copper alloy grades
- High electrical conductivity — 101 % IACS, better than 98% of copper alloy grades
- Forms and bends easily — 95/100, better than 94% of copper alloy grades
- Polishes to a fine finish — 85/100, better than 92% of copper alloy grades
Limitations
- Difficult to machine — 20/100, worse than 98% of copper alloy grades
- Low strength — 85 MPa (12.3 ksi), worse than 89% of copper alloy grades
Cu-OF-OS025 properties
Typical room-temperature values for Cu-OF-OS025; 20 are specific to this condition. Other listed values are Cu-OF reference data and may not represent this condition. Bars are the position among copper alloy grades.
Physical3
Cu-OF-OS025 has a density of 8.94 g/cm³ (0.323 lb/in³), heavier than 90% of copper alloy grades. It melts at 1,083°C (1,981 °F).
Mechanical13
Cu-OF-OS025 has a yield strength of 85 MPa (12.3 ksi) and a tensile strength of 235 MPa (34.1 ksi) — weaker than 89% of copper alloy grades. Elongation at break is 42% and the elastic modulus is 115 GPa (16.7 Msi).
Thermal6
Cu-OF-OS025 is rated for continuous service to 200°C (392 °F). It conducts heat at 391 W/m·K (225.9 BTU/hr·ft·°F), better than 98% of copper alloy grades. Thermal expansion is 17.7 µm/m·K (9.83 µin/in·°F).
Electrical3
Cu-OF-OS025 conducts electricity at 101 % IACS, better than 98% of copper alloy grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 86% of copper alloy grades.
Sustainability4
Producing a kilogram of Cu-OF-OS025 takes about 57 MJ of energy and emits 4 kg of CO₂ — less than 52% of copper alloy grades. Typical recycled content is 25%.
Manufacturability8
Cu-OF-OS025's machinability is poor (20/100, worse than 98% of copper alloy grades); weldability good (55/100); formability excellent (95/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Cu-OF-OS025
Is Cu-OF easy to machine?
Gummy and abrasive-free but built-up-edge prone: use sharp, polished, high-positive-rake carbide, high speed (200–400 m/min), heavy flood coolant and avoid dwelling; AM parts machine similarly to annealed bar.
Can Cu-OF be welded?
Best joined by EB, laser (green preferred) or GTAW/GMAW with 150–500 °C preheat because of the huge thermal conductivity; brazing and soldering are excellent, and no hydrogen embrittlement risk since O ≤10 ppm.
Can Cu-OF be formed, bent or molded?
Outstanding cold formability in the soft tempers (deep draw, spin, bend to 0T); anneal 400–600 °C in inert or reducing atmosphere between heavy reductions; L-PBF needs green/blue laser or high-power IR plus preheat to overcome reflectivity.
What surface finishes work on Cu-OF?
Not anodisable — electropolish or bead-blast then plate (Ni barrier + Ag/Au for RF), or protect with benzotriazole/clear lacquer; AM surfaces normally need chemical/abrasive polishing to reach low RF loss.
Cu-OF 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 |
|---|---|---|
| O≤10 ppm; AM powder typically 150–400 ppm total O after atomisation | ≤ 0 | 5×10⁻⁴ |
| PTU1 limit (GB/T 5231) | ≤ 3×10⁻⁴ | — |
| BiTU1 limit | ≤ 0 | — |
| PbTU1 limit | ≤ 0 | — |
| STU1 limit | ≤ 0 | — |
| CuCu + Ag, ASTM B170 Grade 2 / GB/T 5231 TU1 | ≥ 99.95 (balance) | — |
Cu-OF-OS025 — frequently asked
What is Cu-OF-OS025 used for?
Cu-OF-OS025 is typically used for induction coils, heat sinks, electrical contacts and waveguides. In short: highest-conductivity AM copper; oxygen-free, embrittlement-free; soft with low machinability.
What is the yield strength of Cu-OF-OS025?
Cu-OF-OS025 has a typical yield strength of 85 MPa (12.3 ksi) and a tensile strength of 235 MPa (34.1 ksi) — weaker than 89% of copper alloy grades. Strength varies by condition: see the 14 listed tempers.
Is Cu-OF-OS025 easy to machine?
Not especially — machinability is rated poor (20/100, worse than 98% of copper alloy grades). Gummy and abrasive-free but built-up-edge prone: use sharp, polished, high-positive-rake carbide, high speed (200–400 m/min), heavy flood coolant and avoid dwelling; AM parts machine similarly to annealed bar.
Can Cu-OF-OS025 be welded?
Yes — weldability is rated good (55/100). Best joined by EB, laser (green preferred) or GTAW/GMAW with 150–500 °C preheat because of the huge thermal conductivity; brazing and soldering are excellent, and no hydrogen embrittlement risk since O ≤10 ppm.
What surface finishes work on Cu-OF-OS025?
Not anodisable — electropolish or bead-blast then plate (Ni barrier + Ag/Au for RF), or protect with benzotriazole/clear lacquer; AM surfaces normally need chemical/abrasive polishing to reach low RF loss.
Can Cu-OF-OS025 be formed, bent or molded?
Outstanding cold formability in the soft tempers (deep draw, spin, bend to 0T); anneal 400–600 °C in inert or reducing atmosphere between heavy reductions; L-PBF needs green/blue laser or high-power IR plus preheat to overcome reflectivity.
What is the maximum service temperature of Cu-OF-OS025?
Cu-OF-OS025 is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASTM B170 — Oxygen-Free Electrolytic Copper Refinery Shapes — ASTM International (2019)
- CDA Alloy Datasheet C10200 (OF Copper) — Copper Development Association (2023)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- Gas-atomised pure copper (Cu-OF) AM powder datasheets — AM powder producers (SLM/EOS/Trumpf/Sandvik-class data) (2024)
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.