What Makes C10200 an Oxygen-Free Grade
C10200 copper is produced by converting selected refined cathodes and castings under closely controlled conditions, so that oxygen pickup is avoided from melting through casting and drawing. The result is a hollow round tube with a copper content of 99.95% minimum, silver counted as copper, residual oxygen of about 0.001%, and electrical conductivity of at least 100% IACS. With impurity levels this low, the properties of the pure metal itself dominate the behaviour of the tube.
Oxygen-free copper is not a higher-conductivity metal than common electrolytic tough pitch copper; the conductivity figures are close. Its advantage is chemical stability. With no oxide particles lining the grain boundaries, the tube survives hydrogen-bearing brazing and welding atmospheres without embrittlement, holds vacuum, and keeps the clean dense structure needed for glass-to-metal seals and hermetic components.
Chemical Composition and Temper Range
| Element | Limit | Note |
|---|---|---|
| Cu | 99.95% min | Silver is counted as copper |
| O | 0.0010% | Oxygen-free, typically quoted as 0.001% |
Hollow round tube is supplied in a spread of tempers that run from soft annealed through quarter hard, half hard and hard drawn conditions. Section size and cold work level are agreed with the customer because the same designation can be produced in flat products, rod or shaped sections, and the mechanical values shift with the amount of drawing the wall has seen.
Mechanical Properties by Temper
| Temper | Form | Tensile strength | Yield strength (0.5% extension) | Elongation |
|---|---|---|---|---|
| H02 | Flat product, 1 mm section | 290 MPa typical | 248 MPa typical | 14% |
| H04 | Flat product, 6.35 mm section | 345 MPa typical | 310 MPa typical | 12% |
| M20 | Rod, 25.4 mm section | 221 MPa typical | 69 MPa typical | 50% |
| M30 | Shaped section, 12.7 mm | 221 MPa typical | 69 MPa typical | 50% |
In tube form the same trend holds: as the drawing reduction rises, tensile and yield strength climb and elongation falls. Soft annealed hollow tube takes the tightest bend radii and the deepest forming operations, while harder tempers hold straightness and resist deformation in service.
Why Oxygen-Free Rather Than Tough Pitch
No oxygen means no hydrogen embrittlement when the assembly is brazed or welded in a reducing atmosphere.
Conductivity and purity stay stable in electronic and vacuum service, where a small oxide film would change contact behaviour.
The structure is clean and dense, which supports glass-to-metal seals and hermetic feed-throughs.
Pumping and degassing behaviour suits vacuum equipment tubing and cryogenic transfer lines.
Brazed joints form evenly because the wall is free of internal oxide stringers.
Industrial Uses
The grade is chosen where cleanliness, vacuum integrity or brazing reliability matters more than the last few percent of price.
Electronics: microwave tubes, copper-to-glass seals, transistor components, lead-in wires
Conductors: bus conductors, busbars, coaxial cables and coaxial tube, waveguides
Vacuum: vacuum seals, vacuum equipment tubing, hermetic assemblies
Processing: billet mould tube, extrusion cans for powder metallurgy
Fluid systems: liquefied petroleum gas service tubing, medical oxygen tubing, cryogenic transfer lines
Power devices: klystron components and cavity resonators
Availability, Standards and Testing
Seamless hollow tube is routinely supplied to ASTM B75, B188 and B280, sheet to ASTM B152 and bar to ASTM B187, with equivalent designations in JIS C1020, BS Cu-OF and GB T1 or T2. Production sizes run from 2 mm to 914 mm outside diameter with wall thickness from 0.2 mm to 120 mm, in straight lengths or coils, and intermediate sizes are made to drawing.
Spectrometer analysis of the heat and of the finished product
Conductivity test to confirm the conductivity figure at final gauge
Eddy current examination of the tube wall over its full length
Hydrostatic pressure test where the application requires it
Certificate to EN 10204 3.1 with conductivity and oxygen results for electronic work
Frequently Asked Questions
Q: Is oxygen-free copper more conductive than C11000?
No. C10200 holds at least 100% IACS and C11000 is a similar figure. The oxygen-free grade is chosen for brazing and vacuum stability, not for a higher conductivity number.
Q: What does OFHC mean?
OFHC stands for oxygen-free high conductivity. It describes copper that has been processed so that oxygen is kept out of the melt, leaving the metal with 99.95% copper or better and conductivity at or above 100% IACS.
Q: When should a hollow round tube be used instead of a bar?
Whenever the part is a conductor, a conduit, a vacuum line or a mould tube with a bore. A hollow tube removes weight and metal cost while keeping the conductive cross-section at the wall.
Q: Can this tube be welded in a hydrogen atmosphere?
Yes. That is the defining reason for buying it. Hydrogen embrittlement, the failure mode of tough pitch copper in reducing atmospheres, cannot start because there is no oxygen in the metal to react with.
Q: What temper is used for bellows and waveguides?
Cold-worked tempers such as H02 and H04. They provide the yield strength needed to hold a formed profile and to carry structural loads in electronic hardware.
Q: How is oxygen content checked?
By the analysis supplied with the heat and by the certification issued with the finished tube, which reports the oxygen figure and conductivity for the lot actually shipped.
