Free machining grades of brass set the standard for machining, by which other metals are compared and CZ121 offers the highest possible machinability of any copper alloy.
Brasses are alloys of copper and zinc and CZ121 is an alpha/beta alloy that contains 37-45% zinc. It also has a 3% lead content to improve machinability. The lead remains insoluble in the microstructure of the brass and the soft particles act as chip breakers.
CZ121 is the most widely used of all the brasses due to its suitability for high speed machining operations and also the manufacture of intricate parts. Its combination of machinability, thread rolling and knurling characteristics, combined with its good strength, an ease of soldering/brazing and a high resistance to corrosion makes it the ideal choice for many brass components throughout industry.
| Product Form | Imperial Sizes | Metric Sizes | |
|---|---|---|---|
| From | To | ||
| Round Bar | 1⁄8" | 4 1⁄2" | 3.0mm - 255.0mm |
| Hexagon Bar | 0.248" | 3" | 5.0mm - 65.0mm |
| Square Bar | 1⁄4" | 3" | |
| Flat Bar | 3⁄8" x 1⁄8" | 4" x 2" |
CZ121/CW614N corresponds to the following designations but may not be a direct equivalent:
| Chemical Element | % Present |
|---|---|
Copper (Cu) | 57.00 - 59.00 |
Lead (Pb) | 2.50 - 3.50 |
Aluminium (Al) | 0.00 - 0.05 |
Iron (Fe) | 0.00 - 0.30 |
Nickel (Ni) | 0.00 - 0.30 |
Others (Total) | 0.00 - 0.20 |
Tin (Sn) | 0.00 - 0.30 |
Zinc (Zn) | Balance |
| Mechanical Property | Value |
|---|---|
Proof Stress | 230-350 MPa |
Tensile Strength | 360-500 MPa |
Hardness Brinell | 90 to 160 HB |
Elongation A | 20 to 5 % |
| Physical Property | Value |
|---|---|
Density | 8.47 g/cm³ |
Melting Point | 875 °C |
Thermal Expansion | 20.9 x10-6/K |
Modulus of Elasticity | 97 GPa |
Thermal Conductivity | 123 W/m.K |
Electrical Resistivity | 0.062 x10-6 Ω .m |
Soldering of CZ121/CW614N is rated as excellent and brazing is good. Butt welding is fair but all other welding methods are not recommended.
The machinability of alloy CZ121/CW614N is excellent. It has a machinability rating of 100 and is the standard against which the machinability of other alloys is measured.
The corrosion resistance of CZ121/CW614N is fair to excellent.
Cold working of CZ121/CW614N is poor and is not recommended. It can, however, be knurled if required.
Fabrication of CZ121/CW614N by hot working is excellent. It is recommended that hot working be done between 630 and 730°C.
Solution treatment or annealing can be done by rapid cooling after heating to 430-600°C.
