Hardness in C10100 is a direct result of strain hardening during the rolling or drawing process. Because 99.99% pure copper contains no alloying elements for structural rigidity, temper control (from OS025 to H04) is the only method to prevent mechanical failure during bending or machining. Selecting the wrong temper leads to excessive springback in busbars or brittle fracturing in deep-drawn components. For C10100 Oxygen-Free Electronic copper, hardness must be balanced against the 101% IACS conductivity requirement, as extreme cold work can introduce lattice dislocations that slightly increase resistivity.
How do C10100 tempers correspond to hardness values?
C10100 hardness is measured on the Rockwell F (HRF) or Vickers (HV) scales depending on the material thickness. In its Soft (Annealed) state, the material is highly ductile, but as it is cold-worked into Half Hard (H02) or Full Hard (H04) states, the yield strength increases significantly.
When specifying C10100 Round, Square & Flat Bar, the temper dictates the machining behavior. "Gummy" annealed copper often leads to poor surface finishes, while 1/2 Hard material provides cleaner chip evacuation.
C10100 Hardness and Strength by Temper
| Temper Name | ASTM Code | Rockwell F (HRF) | Vickers (HV) | Tensile Strength (ksi) |
| Soft (Annealed) | OS025 | 40 - 45 | 45 - 55 | 30 - 34 |
| 1/4 Hard | H01 | 60 - 75 | 75 - 95 | 34 - 42 |
| Half Hard | H02 | 77 - 89 | 90 - 110 | 37 - 46 |
| Full Hard | H04 | 90 - 98 | 110 - 130 | 43 - 52 |
Why use Vickers (HV) instead of Rockwell (HRF) for C10100?
Rockwell F is common for thick C10100 Plate and Sheet, but it is unreliable for thin foils. The ball indenter in a Rockwell test can "bottom out" on thin material, giving a false reading of the anvil instead of the copper.
We use Vickers (HV) for CNC parts because C10100 is prone to surface smearing. It verifies structural integrity better than Rockwell, ensuring the copper won't 'smush' or deform when you torque down the bolts during assembly.
How does hardness affect bending and forming limits?
The harder the temper, the larger the minimum bend radius required. Attempting a 1T bend on a Full Hard (H04) C10100 Seamless Tube will result in outer-diameter fracturing.
Annealed (OS025): Highest ductility; used for deep drawing and tight bends. Zero springback.
Half Hard (H02): The industry standard for busbars. Balanced stiffness and formability.
Full Hard (H04): Maximum dimensional stability. Requires a bend radius of at least 2.5x thickness.
Misidentifying the temper is a primary reason for the C10100 sourcing traps where buyers receive material that cracks during simple fabrication.
Bending Limits for C10100 Plates
| Temper | Min Bend Radius (90°) | Workability |
| Soft (OS025) | 0.5 x Thickness | Excellent |
| 1/2 Hard (H02) | 1.5 x Thickness | Fair |
| Full Hard (H04) | 2.5 x Thickness | Poor (Risk of cracking) |
FAQ
1. Does 101% IACS conductivity drop if the copper is "Full Hard"?
Yes. Heavy cold-working creates dislocations in the copper lattice that impede electron flow. While the drop is minor (usually <0.5%), ultra-precision applications may require a stress-relief anneal to return to the full 101% IACS potential.
2. Can I restore hardness after a welding or brazing cycle?
No. High-temperature processes like vacuum brazing will naturally anneal the material. A Half Hard (H02) bar will become Soft (OS025) in the heat-affected zone (HAZ), which may cause the component to sag or lose its structural rigidity.
3. How do you measure hardness on C10100 foil?
Standard Rockwell is not possible for foils. We use Micro-Vickers with a low gram-load or the Rockwell 15T superficial scale to prevent the "anvil effect" from ruining the measurement.
4. Why is my "Soft" bar harder on the outside?
This is "skin hardness" caused by drawing dies. The outer surface undergoes localized strain hardening while the core remains annealed. This can cause inconsistent results in precision CNC turning if tool pressure isn't adjusted.
5. Does the Max 5ppm oxygen limit affect hardness?
Oxygen content doesn't change the initial hardness, but it prevents "hydrogen embrittlement" which can lead to brittle failure during high-temp forming. Without the Max 5ppm oxygen limit, the copper would become brittle after brazing regardless of its initial temper.
6. At what temperature does C10100 begin to soften?
C10100 starts to recrystallize (anneal) at approximately 200°C - 250°C if held for a long duration. In high-power busbars experiencing extreme I-squared R heating, the material can lose its temper over several years.
GNEE METAL Product Range
| Product Type | Shapes Available | Common Grades | Diameter/Thickness Range | Length/Width Range | Applications |
|---|---|---|---|---|---|
| Copper Tubes | Round, Square, Rectangular, Coiled | C10100, C10200, C11000, C12200, C12000 | OD: 0.5mm - 300mm Wall: 0.1mm - 20mm | Up to 6000mm or custom | HVAC, Plumbing, Heat Exchangers, Refrigeration, Hydraulic Lines |
| Copper Plates & Sheets | Flat Sheets, Perforated, Embossed, Tread Plate | C10100, C11000, C12200, C23000, C26000 | Thickness: 0.1mm - 200mm | Width: Up to 2500mm Length: Up to 6000mm | Electrical Busbars, Roofing, Cladding, Gaskets, Transformers |
| Copper Bars & Rods | Round Bar, Square Bar, Hexagonal Bar, Flat Bar | C10100, C11000, C14500, C17200, C18200 | Diameter: 1mm - 300mm | Length: 1000mm - 4000mm | Machined Components, Electrical Contacts, Busbars, Fasteners |
| Copper Wires | Round Wire, Flat Wire, Square Wire, Stranded, Braided | C11000, C11600, C17200, C17510 | Diameter: 0.05mm - 12mm | Coil weights: 1kg - 500kg | Electrical Wiring, Cables, Springs, Mesh, Welding Wire |
| Copper Strips & Coils | Thin Strip, Foil, Slit Coil, Profile Strip | C11000, C12200, C19400, C26000, C26800 | Thickness: 0.03mm - 5mm | Width: 2mm - 1000mm Coil ID: 300mm - 600mm | Transformers, Radiators, Shielding, Terminals, Connectors |
About Our Factory
We operate a full range of production lines including extrusion presses, cold drawing benches, high-speed rolling mills, slitting lines, and precision CNC machining centers, enabling us to produce copper tubes, plates, bars, wires, and strips entirely in-house. For quality assurance, we maintain a dedicated inspection laboratory equipped with spectral analyzers, universal testing machines, hardness testers, surface roughness testers, and optical measuring instruments. Every batch is tested for chemical composition, mechanical properties, and dimensional accuracy before shipment. Our production capacity reaches 500+ tons per month, and we hold ISO 9001:2015 certification with full traceability from raw material to finished product. Whether you need standard mill stock or custom-processed components, we deliver precision copper products with short lead times and complete material certification.
Get Fast Quote & Logistics Plan
