Kuparinikkeli

Kuparinikkeli, or cupronickel, is a family of copper–nickel alloys in which nickel is the principal alloying element. Common compositions include around 70% copper with 30% nickel (often referred to as CuNi 70/30), as well as other grades such as 80/20 and 90/10. These alloys are designed to balance the ductility of copper with the corrosion resistance provided by nickel.

The primary characteristic of kuparinikkeli is its high resistance to corrosion, especially in seawater and other harsh environments. The alloys also offer good formability and strength-for-a-copper-alloy, with hardness increase achievable through cold working. They are generally not strengthened by traditional heat treatment; instead, strength is largely developed through deformation, while annealing can restore ductility after work hardening. The appearance is a silvery, slightly warm tone, and the material is typically non-magnetic for many practical purposes.

Applications of kuparinikkeli include coinage and various marine and industrial uses. It has long been used in coins due to its durability and relatively low wear, as well as in ship fittings, piping, heat exchangers, valves, and desalination equipment where corrosion resistance is essential. The alloy is also employed in electrical components and architectural hardware where a combination of corrosion resistance and machinability is desired.

Production involves melting and alloying copper with nickel, followed by casting, forming, and extensive mechanical working. Cupronickel grades are standardized in several national and international specifications, with 70/30 and 80/20 compositions being among the most common due to their favorable balance of corrosion resistance and mechanical properties.