Leaded Copper refers to copper alloys containing controlled additions of lead (typically 0.5–4%) to dramatically improve machinability without severely compromising copper’s electrical, thermal, and corrosion- resistant properties.
Lead exists as discrete, insoluble globules in the copper matrix and does not form a solid solution with copper. Common standards include C14500, C14700, C36000 (brass-based) and various leaded bronzes.
Typical Chemical Composition
| Element | Typical Content (%) |
|---|---|
| Copper (Cu) | 96.0 – 99.0 |
| Lead (Pb) | 0.5 – 4.0 |
| Oxygen | Trace |
| Other Elements | Trace |
Leaded Copper Alloy Variants
| Alloy Family | Additional Elements |
|---|---|
| Leaded Copper | Pb only |
| Leaded Bronze | Sn + Pb |
| Leaded Brass | Zn + Pb |
| Free-Machining Copper | Pb + S / Te (minor) |
Key Mechanical Properties
| Property | Typical Range |
|---|---|
| Tensile Strength | 200 – 350 MPa |
| Yield Strength | 70 – 200 MPa |
| Elongation | 10 – 35% |
| Hardness | 60 – 110 HB |
| Elastic Modulus | ~110 GPa |
| Fatigue Resistance | Moderate |
Lead does not strengthen copper — its role is to enhance machinability by chip breaking and lubrication.
Physical Properties
| Property | Value |
|---|---|
| Density | 8.9 – 9.2 g/cm³ |
| Melting Range | 1080 – 1085 °C (Cu base) |
| Electrical Conductivity | 60 – 85% IACS |
| Thermal Conductivity | High |
| Corrosion Resistance | Very Good |
| Magnetic | Non-magnetic |
Metallurgical & Strengthening Behavior
| Mechanism | Contribution |
|---|---|
| Solid Solution Strengthening | From Sn / Zn alloying |
| Lead Addition | No strengthening |
| Cold Working | Moderate |
| Grain Refinement | Limited |
| Heat Treatment | Not heat-treatable |
Fabrication & Workability
| Process | Suitability |
|---|---|
| Machining | Excellent |
| Turning / Milling | Excellent |
| Drilling | Excellent |
| Forging | Moderate |
| Extrusion | Good |
| Welding | Poor |
| Brazing | Good |
| Soldering | Excellent |
Applications of Leaded Copper
Machined Components
Bushings, bearings, valve bodies, fittings, hydraulic components
Electrical & Electronics
Terminals, switchgear components, grounding parts
Automotive & Industrial
Fuel system components, pump parts, precision turned parts
Advantages
✔ Exceptional machinability (90–100% rating)
✔ Faster production & reduced tooling wear
✔ Excellent surface finish with minimal burrs
✔ Stable performance in mass production
Health, Safety & Regulations
Lead is toxic and regulated under RoHS and REACH. Leaded copper is prohibited in potable water and food-contact applications but permitted in industrial, electrical, and automotive uses (with exemptions).
Why Choose Leaded Copper?
Choose leaded copper when high-speed machining, tight tolerances, excellent surface finish, and reliable electrical performance are required and regulatory conditions allow lead usage.