Chemical composition and purity of 99.97% T1 oxygen-free copper
| Element | Requirement | Typical Value |
|---|---|---|
| Copper (Cu) | ≥99.97% | 99.98-99.99% |
| Oxygen (O) | ≤0.002% (20 ppm) | <15 ppm |
| Phosphorus (P) | ≤0.002% | <0.001% |
| Iron (Fe) | ≤0.004% | <0.002% |
| Lead (Pb) | ≤0.003% | <0.001% |
| Antimony (Sb) | ≤0.002% | <0.001% |
| Arsenic (As) | ≤0.002% | <0.001% |
| Bismuth (Bi) | ≤0.001% | <0.0005% |
| Total impurities (excluding oxygen) | ≤0.03% | <0.02% |
Every 0.01% of impurity reduces electrical and thermal conductivity. The 0.07% difference between T1 (99.97%) and T2 (99.90%) translates to about 1% higher conductivity and significantly better weldability.
Electrical conductivity of high-purity T1 copper in IACS
T1 copper has an electrical conductivity of ≥101% IACS at 20°C.
| Electrical Property | Value |
|---|---|
| Conductivity (% IACS) | ≥101% |
| Resistivity at 20°C (Ω·mm²/m) | ≤0.01707 |
| Conductivity at 100°C | ~95% IACS |
| Conductivity at 200°C | ~85% IACS |
How T1 compares to other grades:
| Grade | Conductivity (% IACS) | Difference |
|---|---|---|
| T1 copper | ≥101% | Baseline |
| T2 copper | ≥100% | -1% |
| ASTM C10200 | ≥100% | -1% |
| ASTM C11000 | 100% | -1% |
| Pure silver | 105% | +4% |
| Aluminum 6061 | 61% | -40% |
For a busbar carrying 1000 amps, T1 generates about 1% less heat than C11000. For most applications, this difference is negligible. For high-current switchgear or efficiency-critical systems, it is a real advantage.
Thermal conductivity and heat transfer of oxygen-free copper grade
T1 copper has a thermal conductivity of approximately 391 W/(m·K) at 20°C.
| Thermal Property | Value |
|---|---|
| Thermal conductivity at 20°C | ~391 W/(m·K) |
| Thermal conductivity at 100°C | ~385 W/(m·K) |
| Thermal conductivity at 200°C | ~375 W/(m·K) |
| Thermal diffusivity | ~115 mm²/s |
| Specific heat capacity | 0.385 J/(g·K) |
How T1 compares to other materials:
| Material | Thermal Conductivity (W/(m·K)) |
|---|---|
| T1 copper | ~391 |
| Silver | 429 |
| T2 copper | ~385 |
| ASTM C11000 | ~385 |
| Aluminum 6061 | 167 |
| Brass 70/30 | 120 |
| Stainless steel 304 | 15 |
Applications where thermal performance matters: Heat exchangers, cooling plates, LED heat sinks, power electronics cooling, cryogenic transfer lines, and radiator cores.
Tensile strength and mechanical properties
Annealed (soft) condition - most common for forming and stamping:
| Property | Value |
|---|---|
| Tensile strength | 200 - 250 MPa (29 - 36 ksi) |
| Yield strength (0.2% offset) | 40 - 60 MPa (6 - 9 ksi) |
| Elongation (in 50mm) | ≥30% |
| Hardness (Vickers, HV) | 40 - 60 |
| Hardness (Rockwell F) | 40 - 55 |
Half-hard condition - moderate strength with some formability:
| Property | Value |
|---|---|
| Tensile strength | 250 - 300 MPa (36 - 44 ksi) |
| Yield strength (0.2% offset) | 150 - 200 MPa (22 - 29 ksi) |
| Elongation (in 50mm) | 10% - 20% |
| Hardness (Vickers, HV) | 70 - 90 |
Hard (full hard) condition - maximum strength, minimum ductility:
| Property | Value |
|---|---|
| Tensile strength | 300 - 360 MPa (44 - 52 ksi) |
| Yield strength (0.2% offset) | 250 - 300 MPa (36 - 44 ksi) |
| Elongation (in 50mm) | 2% - 6% |
| Hardness (Vickers, HV) | 90 - 110 |
How to choose the right temper:
| If you need... | Choose... |
|---|---|
| Deep drawing, complex stamping, tight bends | Annealed |
| General fabrication, moderate forming | Half-hard |
| Spring contacts, structural busbars, maximum stiffness | Hard |
T1 Copper Physical properties
| Physical Property | Value |
|---|---|
| Density at 20°C | 8.94 g/cm³ (0.323 lb/in³) |
| Melting point | 1083°C (1981°F) |
| Specific heat capacity at 20°C | 0.385 J/(g·K) |
| Coefficient of thermal expansion (20-300°C) | 17.0 × 10⁻⁶ /K |
| Modulus of elasticity (Young's modulus) | 115 - 130 GPa (16.7 - 18.9 msi) |
| Modulus of rigidity (shear modulus) | 44 - 48 GPa |
| Poisson's ratio | 0.34 - 0.35 |
| Electrical resistivity at 20°C | ≤0.01707 Ω·mm²/m |
| Thermal diffusivity | ~115 mm²/s |
Practical implications:
Density 8.94 g/cm³: A 1m x 1m x 1mm sheet weighs 8.94 kg. Use this for shipping and structural calculations.
Melting point 1083°C: Well above brazing temperatures (600-800°C) and soldering temperatures (200-400°C). No risk of melting during joining.
Thermal expansion 17 ppm/K: A 1m long busbar heated from 20°C to 80°C expands by about 1mm. Account for this in mounting systems.
Weldability and joining specifications for T1 copper
T1 copper has excellent weldability due to its low oxygen content.
| Joining Method | Suitability | Notes |
|---|---|---|
| TIG welding | Excellent | No flux needed, clean welds, no porosity |
| MIG welding | Excellent | Use deoxidized filler wire (ERCu) |
| Resistance welding | Excellent | Consistent results, no oxidation issues |
| Brazing | Excellent | Flows well, strong joints |
| Soldering | Excellent | Easy to wet, strong bonds |
| Mechanical joining | Excellent | Bolts, rivets, crimps all work |
Recommended TIG welding parameters for T1 copper sheet:
| Thickness | Tungsten Size | Amperage (DCEN) | Filler Rod |
|---|---|---|---|
| 1mm | 1.6mm | 80-120 A | ERCu |
| 2mm | 2.4mm | 150-200 A | ERCu |
| 3mm | 3.2mm | 220-280 A | ERCu |
| 5mm | 4.0mm | 300-400 A | ERCu |
Why T1 welds better than T2 or C11000: Those grades contain 200-500 ppm oxygen. During welding, oxygen reacts with hydrogen to form water vapor, creating porosity in the weld. T1 has almost no oxygen, so no porosity, no embrittlement, no cracking.
Cryogenic performance of t1 copper at low temperatures
T1 copper performs excellently at cryogenic temperatures and has no ductile-to-brittle transition.
Conductivity at cryogenic temperatures:
| Temperature | Conductivity (% IACS) | Notes |
|---|---|---|
| 20°C (room temperature) | ≥101% | Baseline |
| -196°C (liquid nitrogen) | ~300% | Increases dramatically |
| -269°C (liquid helium) | ~500% | Near theoretical maximum |
Mechanical properties at cryogenic temperatures:
| Temperature | Tensile Strength | Elongation |
|---|---|---|
| 20°C | 200-250 MPa | ≥30% |
| -196°C | ~400 MPa | ~40% |
| -269°C | ~500 MPa | ~30% |
Why T1 is preferred for cryogenic systems:
No ductile-to-brittle transition (unlike steel)
Strength increases as temperature drops
Ductility remains high
Thermal conductivity becomes extremely high
No embrittlement from impurities (purity matters at low temperatures)
Applications: Liquid nitrogen transfer lines, liquid helium transfer lines, cryostat components, cold heads for cryocoolers, thermal straps, superconducting magnet supports, space-based instruments.
Corrosion resistance of 99.97% T1 pure copper in various environments
T1 copper has excellent corrosion resistance in many common environments.
| Environment | Corrosion Resistance | Notes |
|---|---|---|
| Atmospheric (rural) | Excellent | Forms protective patina |
| Atmospheric (industrial) | Good | Patina forms, may be darker |
| Atmospheric (marine) | Fair to good | Can pit in salt spray |
| Fresh water | Excellent | Safe for potable water |
| Distilled water | Good | Very low corrosion rate |
| Seawater | Fair | Pitting and erosion possible |
| Neutral salt solutions | Good | Similar to fresh water |
| Non-oxidizing acids | Fair | Depends on concentration |
| Oxidizing acids (nitric, concentrated sulfuric) | Poor | Not recommended |
| Ammonia and ammonium compounds | Poor | Causes stress corrosion cracking |
Corrosion rates for reference:
In rural atmosphere: <0.001 mm/year
In industrial atmosphere: 0.001-0.005 mm/year
In fresh water: 0.002-0.005 mm/year
In seawater: 0.01-0.05 mm/year (with pitting risk)
Dimensional tolerances per GB/T 5231 for t1 copper sheet and rod
Sheet and plate thickness tolerances (annealed):
| Thickness (mm) | Tolerance (± mm) |
|---|---|
| 0.1 - 0.5 | 0.02 - 0.05 |
| 0.5 - 1.0 | 0.05 - 0.08 |
| 1.0 - 2.0 | 0.08 - 0.12 |
| 2.0 - 5.0 | 0.12 - 0.20 |
| 5.0 - 10.0 | 0.20 - 0.30 |
| 10.0 - 20.0 | 0.30 - 0.50 |
| 20.0 - 50.0 | 0.50 - 1.00 |
Round rod diameter tolerances:
| Diameter (mm) | Tolerance (± mm) |
|---|---|
| 1 - 10 | 0.03 - 0.08 |
| 10 - 30 | 0.08 - 0.15 |
| 30 - 60 | 0.15 - 0.25 |
| 60 - 100 | 0.25 - 0.40 |
Strip width tolerances (slit edge):
| Width (mm) | Tolerance (± mm) |
|---|---|
| Up to 100 | 0.10 - 0.20 |
| 100 - 300 | 0.20 - 0.40 |
| 300 - 600 | 0.40 - 0.80 |
T1 VS T2 Copper
| Property | T1 Copper | T2 Copper | ASTM C10200 | ASTM C11000 |
|---|---|---|---|---|
| Minimum Cu (%) | 99.97 | 99.90 | 99.95 | 99.90 |
| Oxygen content (ppm) | <20 | 200-500 | <20 | 200-500 |
| Oxygen-free? | Yes | No | Yes | No |
| Conductivity (% IACS) | ≥101 | ≥100 | ≥100 | 100 |
| Thermal conductivity (W/m·K) | ~391 | ~385 | ~391 | ~385 |
| Tensile strength annealed (MPa) | 200-250 | 200-250 | 200-250 | 200-250 |
| Elongation annealed (%) | ≥30 | ≥30 | ≥30 | ≥30 |
| Weldability | Excellent | Fair | Excellent | Poor |
| Hydrogen embrittlement risk | None | High | None | High |
| Vacuum outgassing | Very low | Moderate | Very low | Moderate |
| Relative price | Higher | Lower | Highest | Low |
Quick selection guide:
| If you need... | Choose... |
|---|---|
| Oxygen-free copper | T1 or C10200 |
| Highest conductivity | T1 |
| Weldability | T1 or C10200 |
| Lowest cost for general use | T2 or C11000 |
| ASTM-certified material | C10200 or C11000 |
| Chinese material at good price | T1 for demanding, T2 for general |
FAQ
1. What is the electrical conductivity of T1 copper?
T1 copper has electrical conductivity of ≥101% IACS at 20°C. This is higher than standard C11000 electrolytic copper (100% IACS) and comparable to other oxygen-free coppers. The high conductivity comes from the 99.97% purity and extremely low impurity levels.
2. What is the thermal conductivity of T1 copper?
T1 copper has thermal conductivity of approximately 391 W/(m·K) at 20°C. This is one of the highest values among engineering metals, second only to silver. For comparison, aluminum 6061 is 167 W/(m·K) and stainless steel 304 is 15 W/(m·K).
3. What is the tensile strength of T1 copper?
The tensile strength depends on temper. Annealed T1 has 200-250 MPa (29-36 ksi). Half-hard has 250-300 MPa (36-44 ksi). Hard (full hard) has 300-360 MPa (44-52 ksi). Most T1 sheet and strip is supplied annealed unless specified otherwise.
4. Is T1 copper magnetic?
No, T1 copper is not magnetic. Copper is diamagnetic, meaning it is very weakly repelled by magnetic fields. For practical purposes, T1 copper is non-magnetic and can be used in MRI machines, sensitive electronic equipment, and any application where magnetic materials are prohibited.
5. What is the melting point of T1 copper?
T1 copper melts at 1083°C (1981°F). This is standard for pure copper. The melting point is well above brazing temperatures (600-800°C) and soldering temperatures (200-400°C), so there is no risk of melting during normal joining processes.
6. What is the density of T1 copper?
T1 copper has density of 8.94 g/cm³ at 20°C (0.323 lb/in³). A 1m x 1m x 1mm sheet weighs 8.94 kg. A 1m long 10mm diameter rod weighs about 0.7 kg. Use these numbers for shipping calculations and structural design.
7. Can T1 copper be heat treated?
No, pure copper like T1 cannot be heat treated for strengthening. Unlike steel or aluminum alloys, pure copper does not respond to heat treatment. Strength is achieved only through cold working (rolling, drawing). Annealing softens the material by removing the effects of cold work.
8. What is the hardness of T1 copper?
Hardness depends on temper. Annealed T1 has Vickers hardness of 40-60 HV. Half-hard is 70-90 HV. Hard (full hard) is 90-110 HV. For reference, annealed T1 is very soft and can be scratched with a fingernail. Hard T1 is significantly stiffer but still machinable.
9. Does T1 copper corrode?
T1 copper has excellent corrosion resistance in air, fresh water, and neutral salt solutions. It forms a protective patina over time. However, it corrodes in strong oxidizing acids (nitric acid, concentrated sulfuric acid), ammonia solutions, and seawater (pitting risk). For most indoor electrical applications, corrosion is not a concern.
10. What is the modulus of elasticity of T1 copper?
The modulus of elasticity (Young's modulus) of T1 copper is 115-130 GPa (16.7-18.9 msi). This is standard for all copper grades. It is about one-third the modulus of steel (200 GPa), meaning copper is about three times more flexible than steel under the same load.
11. What is the coefficient of thermal expansion of T1 copper?
T1 copper has coefficient of thermal expansion of 17.0 × 10⁻⁶ /K from 20-300°C. This means a 1m long copper bar expands by 0.017mm for every 1°C temperature increase. For a 1m bar heating from 20°C to 80°C, expansion is about 1mm. Always account for thermal expansion in long busbar runs.
