cupronickels

Cupronickels are copper-nickel alloys in which nickel is the principal alloying element. They belong to a family of corrosion-resistant alloys with copper as the base metal and nickel contents typically in the range of about 10 to 40 percent. The most common commercial grades are around 70 percent copper and 30 percent nickel (70/30) and 75/25; other grades with higher copper content, such as 80/20, are used for specialized applications such as seawater piping and condenser tubes.

The key properties of cupronickels include excellent corrosion resistance in seawater and other chloride environments, along with good strength and hardness for copper alloys. They remain ductile and workable over a wide temperature range and are non-magnetic. Nickel reduces the electrical conductivity relative to pure copper, while providing enhanced mechanical performance and fatigue resistance.

Manufacture and forms: cupronickels are produced by alloying copper with nickel in smelting operations, then casting and thermomechanically working the material. They are commonly produced as sheets, plates, tubes, bars, and wires, as well as clad stock. Practical forms include marine piping and heat-exchanger tubing, coins in some currencies, and architectural or decorative hardware.

Applications and history: cupronickel alloys have broad use in coinage and marine equipment due to their corrosion resistance and physical properties. The term distinguishes these alloys from other copper-nickel systems such as nickel silver (copper-nickel-zinc) and Monel (nickel-rich copper-nickel). Development and adoption occurred in the late 19th and 20th centuries, with ongoing use in modern coinage, ships’ fittings, and related hardware.