Three Grades, Three Different Jobs
The three designations are frequently quoted together because they are all supplied as plate and sheet, yet they solve different engineering problems. C11000 and C10200 are high-conductivity coppers that differ mainly in oxygen content; C17200 is a precipitation-hardening copper-beryllium alloy that trades conductivity for very high strength and hardness.
Selection therefore starts with one question: does the part need maximum conductivity, or maximum strength? Everything else, including corrosion behaviour, formability and cost, follows from that answer.
Composition Comparison
| Element | C11000 | C10200 | C17200 |
|---|---|---|---|
| Copper | 99.90% minimum including silver | 99.95% minimum including silver | Balance |
| Oxygen | 0.040% maximum (0.02-0.04% typical) | 0.001% maximum | Not applicable |
| Beryllium | - | - | 1.80-2.00% |
| Nickel plus cobalt | - | - | 0.20% minimum |
| Other impurities | 0.05% maximum total | 0.05% maximum total | Per ASTM B194 limits |
| Principal standard | ASTM B152, B124, B187 | ASTM B152, B124, B188 | ASTM B194, B196 |
C11000 is electrolytic tough pitch copper and C10200 is oxygen-free copper; both are described in ASTM B152 for flat rolled products, with C11000 additionally covered by ASTM B187 for busbar. C17200 is covered by ASTM B194 for plate, sheet, strip and rolled bar, and carries the European designation CuBe2. C11000 and C10200 also appear internationally as CW004A and CW008A respectively under EN 1412, and as C1100 and C1020 in the Japanese system.
Property Comparison
| Property | C11000 | C10200 | C17200 |
|---|---|---|---|
| Electrical conductivity | 100% IACS minimum | 100% IACS minimum | about 22% IACS in the aged temper |
| Thermal conductivity | about 390 W/(m K) | about 390 W/(m K) | substantially lower than pure copper |
| Tensile strength, soft | about 210-250 MPa | about 200-250 MPa | about 400-580 MPa solution annealed |
| Tensile strength, hard/aged | up to about 400 MPa | up to about 400 MPa | about 1140-1380 MPa peak aged |
| Hardness, aged or hard | about 90-110 HV | about 90-110 HV | about 36-42 HRC |
| Density | 8.94 g/cm³ | 8.94 g/cm³ | about 8.25 g/cm³ |
| Response to heat treatment | None | None | Age hardenable |
Plate and Sheet Supply Conditions
Flat rolled copper is normally defined so that sheet extends to about 4.8 mm in thickness and plate begins above that figure. Standard widths commonly run to 1220 mm and beyond, with lengths from roughly 900 mm up to 3600 mm and larger on request. Surface finishes include mill finish, bright annealed, polished, brushed and pre-painted for architectural work.
Temper selection differs by grade. C11000 and C10200 are ordered in soft O60/O61 conditions for forming, and in H02 or H04 conditions where the finished part needs stiffness. C17200 is ordered in the solution annealed condition when the part must be formed before hardening, and in a cold worked plus aged condition when the strength must be present as delivered. Age hardening is carried out at approximately 315-345 C for two to three hours, which develops the strength while restoring part of the conductivity.
Applications and Selection Guidance
C11000 plate and sheet are used for busbars, switchgear components, roofing and architectural panels, and general electrical fabrication. C10200 is selected whenever the service involves vacuum, hydrogen-bearing atmospheres or high-integrity brazing, as in vacuum device components, heat exchanger parts and high purity electrical hardware. C17200 is chosen for spring contacts, diaphragms, precision instrument parts, mould inserts and other components that need high strength, hardness and fatigue resistance in a copper-based material.
A practical selection sequence is to define the conductivity requirement first, then the strength requirement, then the fabrication route. If conductivity above roughly 80% IACS is essential, only the pure coppers are viable and strength must be obtained through temper and geometry. If high strength dominates and moderate conductivity is acceptable, the precipitation-hardening grade is the appropriate choice.
FAQ
Q: What is the main difference between C11000 and C10200?
Oxygen content. C11000 is tough pitch copper with up to 0.040% oxygen, while C10200 is oxygen-free at 0.001% maximum, which makes it suitable for vacuum and reducing-atmosphere service.
Q: Why is C17200 so much stronger?
It contains 1.80-2.00% beryllium plus nickel and cobalt, which form fine precipitates during age hardening and block dislocation movement, raising strength at the cost of conductivity.
Q: Which grade should be used for electrical busbar?
C11000 is the conventional choice for busbar because it combines full conductivity with adequate formability and lower cost than the oxygen-free grade.
Q: Is C17200 supplied ready to use?
It can be supplied already hardened, or in the solution annealed condition for forming before the ageing treatment.
Q: How thick does sheet become plate?
The customary dividing line is about 4.8 mm, above which the product is described as plate.
Q: Can these grades be welded?
The pure coppers solder and braze readily and can be resistance welded; the beryllium-bearing alloy requires controlled procedures because of the beryllium content in fumes and dust.
