White copper bar is a nickel-zinc-copper alloy. White copper bars based on copper and nickel-zinc alloy with the addition of other elements such as lead, manganese, and aluminum are correspondingly referred to as lead white copper bar, manganese white copper bar, aluminum white copper bar, etc. Copper-nickel-zinc alloys exhibit good corrosion resistance, moderate strength, high plasticity, and can be processed under hot and cold pressure conditions. They also possess excellent electrical properties, making them not only suitable as structural materials but also important for high-resistance and thermocouple alloys.
Common white copper bars mainly include four grades: B0.6, B5, B19, and B30. The most commonly used grades in the market are B12, B18, and C7941. The American standard includes a wider range of grades. White copper bar is a continuous solid solution formed by Cu and Ni, with a face-centered cubic lattice, as shown in Figure 1-18. When the temperature is below 322 degrees Celsius, the copper-nickel phase diagram exhibits a relatively broad metastable decomposition region in terms of composition and temperature. Adding a third element such as Fe, Cr, Sn, Ti, Co, Si, or Al to Cu-Ni alloys can alter the range and position of the metastable decomposition region while also improving certain properties of the alloy.
Common white copper bars have good cold and hot working properties. They can be easily processed into various shapes such as plates, strips, tubes, bars, profiles, and wires. They also have good welding performance, allowing for soft and hard soldering, gas-shielded arc welding, and resistance welding. Their machinability is 20% that of free-cutting brass HPb63-3.
Common white copper bars offer good corrosion resistance, moderate strength, high plasticity, and the ability to undergo cold and hot pressure processing. They also exhibit excellent electrical properties, making them not only suitable as structural materials but also important for high-resistance and thermocouple alloys.