Cu-OF vs Cu-ETP: Both high-purity coppers — Cu-OF eliminates oxygen for weldability
Cu-OF vs Cu-ETP
Side-by-side chemical composition and mechanical property comparison.
Overview
Cu-OF
CW008A
Oxygen-free high-conductivity copper. 99.95% Cu min with max 0.001% O — eliminates hydrogen embrittlement risk during welding/brazing in reducing atmospheres. Used for vacuum electronics, waveguides, particle accelerator components, cryogenic systems, and applications where welding in H2-containing atmospheres is required.
Cu-ETP
CW004A
Electrolytic Tough Pitch copper — the most widely used copper grade worldwide. 99.90% Cu min with controlled oxygen content (~0.02-0.04%). Electrical conductivity ≥100% IACS. Used for busbars, motor windings, transformer coils, electrical conductors, roofing, and radiators. Caution: hydrogen embrittlement risk in reducing atmospheres above 370°C.
| Cu-OF | Cu-ETP | |
|---|---|---|
| Material Number | CW008A | CW004A |
| Category | Copper & Brass | Copper & Brass |
| Standard | EN 13601 | EN 13601 |
Chemical composition (wt%)
| Element | Cu-OF | Cu-ETP | Overlap |
|---|---|---|---|
| Cu | ≥ 99.95% | ≥ 99.9% | No overlap |
| O | 0–0.001% | 0–0.04% | OK |
| Bi | — | 0–0.0005% | — |
| Pb | — | 0–0.005% | — |
Mechanical properties
| Property | Cu-OF | Cu-ETP | Unit |
|---|---|---|---|
| tensile_strength | 200–260 | 200–260 | MPa |
| yield_strength | 40–80 | 40–80 | MPa |
| elongation | ≥ 33 | ≥ 33 | % |
Compatibility Assessment
Cu-OF has max 0.001% O (vs 0.04% for Cu-ETP), eliminating hydrogen embrittlement risk. Cu-ETP is cheaper and adequate for most electrical uses. Choose Cu-OF only when welding/brazing in reducing atmospheres or for vacuum applications.
Frequently Asked Questions
Is Cu-OF the same as Cu-ETP?
Cu-OF and Cu-ETP have a 90% composition overlap. Both high-purity coppers — Cu-OF eliminates oxygen for weldability
Can I replace Cu-OF with Cu-ETP?
In many cases, yes. The compositions overlap significantly (90%). However, always verify mechanical property requirements and heat treatment compatibility for your specific application.
What is the difference between Cu-OF and Cu-ETP?
The main differences are in the following elements: Cu. Cu-OF is a Copper & Brass grade, while Cu-ETP is a Copper & Brass grade.
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Data provided for reference only. Always verify against the applicable specification for critical applications.
All data is for reference only. Equivalents indicate similarity, not identity. Always verify against the applicable specification for safety-critical applications. materialref.com accepts no liability for decisions based on this data.