Introduction
This article explains C79200 copper-nickel-zinc leaded nickel silver, covering composition and machining. C79200 is a leaded copper-nickel-zinc alloy, also called leaded nickel silver. It combines a silvery appearance with excellent machinability and is used for precision components, watch parts, optical parts and hardware that require a bright finish and close tolerances.
Composition
C79200 contains about 59.0 to 66.5 percent copper, 11.0 to 13.0 percent nickel and 0.8 to 1.4 percent lead with the balance zinc. The nickel gives the alloy its silvery color and improves corrosion resistance and strength, while the lead provides chip-breaking behavior for high-speed machining.
Properties
Nickel silver has moderate strength with tensile values of about 380 to 550 MPa depending on temper, good resistance to tarnishing in indoor atmospheres, and a bright, easily polished surface. It is harder and stiffer than ordinary brass, which suits small precision parts that must hold dimensional accuracy.
| Element | Typical Range |
|---|---|
| Copper | 59.0 - 66.5% |
| Nickel | 11.0 - 13.0% |
| Lead | 0.8 - 1.4% |
| Zinc | Balance |
Applications
Typical uses are watch and instrument parts, optical components, slide fasteners, keys, medical instruments, decorative hardware and electrical contacts. The material is available as rod, bar, wire and sheet under standards such as ASTM B122 and B151.
Selection and Verification
Specify the temper, dimensions and surface requirement, and verify the nickel, zinc and lead content on the mill certificate. For machined parts, confirm the machinability rating and the plating response of the delivered lot.
