Nickel Forgings
Nickel forgings are resistant to oxidation and heat deformation and can withstand very high temperatures up to 1800 degrees Fahrenheit (982 degrees Celsius). Nickel is predominantly used as an alloying metal, and so is almost always forged as an alloy with other metals such as iron, copper, chromium, aluminum, lead and titanium. The high chromium content in many
nickel alloys also helps them retain their shape at high temperatures and to resist corrosion. Some nickel alloys are referred to as superalloys because of their excellent mechanical strength, stability, corrosion resistance and creep resistance at high temperatures. Nickel forgings are commonly used for turbine components, fittings and valves in jet engines and other aerospace applications, as well as in chemical processing, petroleum refining, electronics, and fresh or salt water marine applications.
Like other metals, nickel alloys can be forged into a wide variety of shapes, either through
open die forging or
closed die forging. Most often nickel forgings are created by heating a pre-shaped piece of nickel or nickel alloy and then using a large hammer or press that forces the workpiece to take the shape of a die. In forging, the metal is never melted or poured; instead the forging process uses extreme and/or repetitive pressure to cause plastic deformation of the metal into the desired shape. Often the forging process proceeds gradually though numerous strikes, and it may require an operator to move the workpiece through a series of impression cavities. Nickel's superior resistance to heat makes nickel alloys to be among the most difficult to forge, requiring temperatures very close to the material's melting point. In addition, because nickel work hardens easily,
cold forging of nickel requires frequent intermediate annealing in order to relieve stresses in the metal and restore its ductility. For these reasons the cost of nickel forgings tends to be higher than standard forgings, so they are rarely used except in applications that call for the special properties of nickel. Nevertheless, nickel forgings are essential to a number of industries that require high performing, reliable metal components for harsh or high temperature conditions.
