Lead brasses are used for their high machinability and atmospheric corrosion resistance. The machinability of brass is increased by the addition of lead because it acts as a microscopic chip breaker and tool lubricant. The leaded brasses are used for copper base screw machine material. The alloys have excellent machinability, good strength and corrosion resistance. Lead can be added to any brass to increase machinability and provide pressure tightness by sealing the shrinkage pores. There are low, medium and high leaded brasses, with lead contents up to 3.5%. The lead brasses are used for architectural hardware, general purpose screw machine parts, screws, valves, fittings, bearings and specialty fasteners. The wrought lead brasses are designated by UNS C31200 through C38500.
| Copper Alloys | Cu | Sn | Pb | Zn | Fe | Ni | P | Al | Mn | Si | Sb | S | Bi |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| C31200 | 87.5-90.5 | - | 0.7-1.2 | Rem. | 0.1 | 0.25 | - | - | - | - | - | - | - |
| C31400 | 87.5-90.5 | - | 1.3-2.5 | Rem. | 0.1 | 0.7 | - | - | - | - | - | - | - |
| C31600 | 87.5-90.5 | - | 1.3-2.5 | Rem. | 0.1 | 0.7-1.2 | 0.04-0.1 | - | - | - | - | - | - |
| C32000 | 83.5-86.5 | - | 1.5-2.2 | Rem. | 0.1 | 0.25 | - | - | - | - | - | - | - |
| C33000 | 65-68 | - | 0.25-0.7 | Rem. | 0.07 | - | - | - | - | - | - | - | - |
| C33200 | 65-68 | - | 1.5-2.5 | Rem. | 0.07 | - | - | - | - | - | - | - | - |
| C33500 | 62-65 | - | 0.25-0.7 | Rem. | 0.15 | - | - | - | - | - | - | - | - |
| C34000 | 62-65 | - | 0.8-1.5 | Rem. | 0.15 | - | - | - | - | - | - | - | - |
| C34200 | 62-65 | - | 1.5-2.5 | Rem. | 0.15 | - | - | - | - | - | - | - | - |
| C34500 | 62-65 | - | 1.5-2.5 | Rem. | 0.15 | - | - | - | - | - | - | - | - |
| C35000 | 60-63 | - | 0.8-2 | Rem. | 0.15 | - | - | - | - | - | - | - | - |
| C35300 | 60-63 | - | 1.5-2.5 | Rem. | 0.15 | - | - | - | - | - | - | - | - |
| C35330 | 59-64 | - | 1.5-3.5 | Rem. | - | - | - | - | - | - | - | - | - |
| C35600 | 60-63 | - | 2-3 | Rem. | 0.15 | - | - | - | - | - | - | - | - |
| C36000 | 60-63 | - | 2.5-3.7 | Rem. | 0.35 | - | - | - | - | - | - | - | - |
| C36500 | 58-61 | 0.25 | 0.25-0.7 | Rem. | 0.15 | - | - | - | - | - | - | - | - |
| C37000 | 59-62 | - | 0.8-1.5 | Rem. | 0.15 | - | - | - | - | - | - | - | - |
| C37100 | 58-62 | - | 0.6-1.2 | Rem. | 0.15 | - | - | - | - | - | - | - | - |
| C37700 | 58-61 | - | 1.5-2.5 | Rem. | 0.3 | - | - | - | - | - | - | - | - |
| C37710 | 56.5-60 | - | 1-3 | Rem. | 0.3 | - | - | - | - | - | - | - | - |
| C38000 | 55-60 | 0.3 | 1.5-2.5 | Rem. | 0.35 | - | - | 0.5 | - | - | - | - | - |
| C38500 | 55-59 | - | 2.5-3.5 | Rem. | 0.35 | - | - | - | - | - | - | - | - |