What C11000 Electrolytic Tough Pitch Copper Is
C11000 is the unified numbering system designation for electrolytic tough pitch copper, the most widely consumed grade of commercial pure copper. The metal is refined electrolytically and then melted under oxidising conditions so that a controlled amount of oxygen remains in the melt, largely as cuprous oxide particles dispersed through the copper matrix. That dispersion produces the classic tough pitch behaviour: the material is highly ductile, conducts electricity and heat close to the theoretical maximum for copper, and remains economical for high volume production of tube, sheet, strip, bar and wire.
Because the oxygen level must stay inside a narrow band, C11000 is not intended for service in reducing or hydrogen bearing atmospheres above roughly 400 °C, where steam pockets can open up at grain boundaries and cause embrittlement. Oxygen free grades are selected for those duties instead.
Equivalent Grades of C11000
C11000 appears in every major designation system. The table below shows the designations most often quoted on mill certificates and purchase specifications.
| System | Equivalent designation |
|---|---|
| UNS | C11000 |
| British Standard | C101, C100, C102, C103, Cu-ETP1 |
| Japanese Industrial Standards | C1100 |
| ISO | Cu-ETP |
| European designation and Werkstoff number | CW004A, 2.0060, 2.0065 |
| Other commercial designations | E-Cu58, CuA1, Cu9, T2, 110 |
When a drawing simply calls for Cu-ETP, C1100 or 2.0060, C11000 is normally the correct substitution, provided the temper and product form match the original requirement.
Chemical Composition and Temper
| Element | Limit | Remark |
|---|---|---|
| Copper (Cu) | 99.90 % minimum | Balance of the alloy |
| Oxygen (O) | 0.0400 % nominal | Present as dispersed oxide |
| Total other elements | 0.10 % maximum | Controlled as residual impurities |
C11000 is supplied in a wide range of tempers, from soft annealed through half hard to hard drawn, and the temper controls strength, bend radius and formability far more than the composition does. A soft temper gives the greatest elongation and is preferred for bending and flaring, while a hard temper is used where stiffness and dimensional stability matter.
Physical Properties
| Property | Metric | US customary |
|---|---|---|
| Density | 8.91 g/cm³ at 20 °C | 0.322 lb/in³ at 68 °F |
| Electrical conductivity | 0.591 MS/m at 20 °C | 101 % IACS at 68 °F |
| Electrical resistivity | 1.71 microhm-cm at 20 °C | 10.3 ohm-cmil/ft at 68 °F |
| Thermal conductivity | 391.1 W/(m·K) at 20 °C | 226.0 Btu·ft/(h·ft²·°F) at 68 °F |
| Melting range | 1065 °C solidus / 1083 °C liquidus | 1949 °F / 1981 °F |
| Modulus of elasticity in tension | 117 000 MPa | 17 000 ksi |
| Modulus of rigidity | 44 130 MPa | 6 400 ksi |
| Specific heat capacity | 393.5 J/(kg·K) at 293 K | 0.092 Btu/(lb·°F) at 68 °F |
| Coefficient of thermal expansion | 16.9 × 10⁻⁶ /K (20–100 °C) | 9.4 × 10⁻⁶ /°F (68–212 °F) |
| Coefficient of thermal expansion | 17.3 × 10⁻⁶ /K (20–200 °C) | 9.6 × 10⁻⁶ /°F (68–392 °F) |
| Coefficient of thermal expansion | 17.6 × 10⁻⁶ /K (20–300 °C) | 9.8 × 10⁻⁶ /°F (68–572 °F) |
| Specific gravity | 8.91 | 8.91 |
The combination of roughly 101 % IACS conductivity and 391 W/(m·K) thermal conductivity is what makes this grade the default choice for busbar, transformer windings, heat exchanger tube and electrical connectors.
Fabrication and Joining Behaviour
| Process | Suitability |
|---|---|
| Soldering | Excellent |
| Brazing | Good |
| Butt welding | Good |
| Gas shielded arc welding | Fair |
| Coated metal arc welding | Not recommended |
| Oxyacetylene welding | Not recommended |
| Seam welding | Not recommended |
| Spot welding | Not recommended |
| Cold working capacity | Excellent |
| Hot forming capacity | Excellent |
| Machinability rating | 20 |
| Forgeability rating | 65 |
Low machinability and low weldability are typical of pure copper: it is gummy under the tool and very thermally conductive, so heat is drawn away from the weld pool faster than most processes can compensate. Where joints are required, soldering and brazing are the practical routes.
Product Forms and Applicable Specifications
| Product form | Specification |
|---|---|
| Bar and rod | ASME SB133, ASTM B133, ASTM B152, SAE J461, J463 |
| Bar, rod and shapes for busbar | ASTM B187 |
| Forging stock, forgings and forging shapes | ASTM B124, ASTM B283 |
| Plate, sheet and strip | AMS 4500, ASTM B152, ASTM B694, SAE J461, J463 |
| Building construction sheet and strip | ASTM B370 |
| Clad sheet and strip | ASTM B506 |
| Lead coated sheet | ASTM B101 |
| Sheet and strip for printed circuits, foil | ASTM B451 |
| Bus pipe and bus tube | ASTM B188 |
| Welded tube | ASTM B447 |
| Hard drawn wire | ASTM B1 |
| Medium hard drawn wire | ASTM B2 |
| Soft wire | ASTM B3, ASTM B48, ASTM B738 |
| Stranded wire | ASTM B8, B496, B470, B286, B229, B226, B174, B173, B172 |
| Tin coated wire | ASTM B246, ASTM B33 |
| Silver coated wire | ASTM B298 |
| Nickel coated wire | ASTM B355 |
| Lead alloy coated wire | ASTM B189 |
| Flat wire | AMS 4500, ASTM B272 |
| Trolley wire | ASTM B47, ASTM B116 |
| Bolts, screws and studs | ASTM F468 |
| Nuts | ASTM F467 |
Frequently Asked Questions
Q: What is the European equivalent of C11000?
Under ISO the grade is Cu-ETP, and in the European designation system it is CW004A with Werkstoff numbers 2.0060 and 2.0065.
Q: Is JIS C1100 the same material as C11000?
Yes. JIS C1100 covers electrolytic tough pitch copper with the same copper minimum and oxygen control, so the two designations describe the same metal.
Q: Why is the oxygen content held at about 0.0400 %?
The residual oxygen combines with copper to form a fine oxide dispersion that improves machinability and casting behaviour while keeping conductivity close to the maximum. Too little oxygen gives a gassy, porous cast structure; too much harms ductility and weldability.
Q: What electrical conductivity does C11000 deliver?
Roughly 101 % IACS at 20 °C, equivalent to 0.591 MS/m or a resistivity of 1.71 microhm-cm.
Q: Which welding processes are suitable?
Brazing, soldering and butt welding perform well. Gas shielded arc welding is rated fair. Oxyacetylene, seam, spot and coated metal arc welding are not recommended for this grade.
Q: Can C11000 be used in hydrogen atmospheres?
No. Above roughly 400 °C in reducing or hydrogen bearing gas, the dispersed oxide reacts to form steam at grain boundaries and the metal cracks. Oxygen free copper is specified for that service.
