Nickel Alloy Components
Nickel alloys are commonly used where extreme corrosion resistance, strength, and components with excellent stiffness and structural integrity are required. Finish characteristics and high-temperature strength make nickel a material chosen for aircraft engine components, liquid-fuelled rockets, turbine engines (both aircraft and land-based), high-temperature applications, and vacuum applications.
Nickel-Copper Alloys (Monel), such as Monel 400 (67% nickel, 30% copper), Monel K500, and Monel R405, are highly machinable relative to other nickel alloys. They possess excellent corrosion resistance and are often used in marine environments, chemical processing, and aerospace applications.
Nickel-Chromium Alloys (Inconel), such as Inconel 600, Inconel 625, and Inconel 718, are known for their exceptional high-temperature strength and corrosion resistance. They are commonly used in aerospace, gas turbines, heat exchangers, and chemical processing industries.
The high nickel content of Inconel 600 provides good corrosion resistance under reducing conditions, while the high chromium content raises its oxidation resistance. It’s a nonmagnetic high-temperature alloy that possesses an excellent combination of high strength and resistance to an ordinary form of corrosion. Inconel 600 is machinable in both hot worked and annealed conditions.
Nickel alloys are among the most difficult to machine metal alloys and create significant challenges for a CNC Swiss. They are also relatively expensive but are often used when no other alloy will provide the properties required for the component application. Inconel is challenging to machine, which can be attributed to its high strength, leading to high cutting forces at the tool tip; therefore, more robust equipment is needed to cope. It does not get any softer when the temperature rises.
Inconel 625 is used for its high strength, excellent fabricability, and outstanding corrosion resistance. Its properties (high corrosion-fatigue strength, high-tensile strength, and resistance to chloride-ion stress-corrosion cracking) make it an excellent choice for sea-water applications such as electrical cable connectors, fasteners, and oceanographic instrument components. The outstanding and versatile corrosion resistance of Inconel 625 under a wide range of temperatures and pressures is a primary reason for its wide acceptance in the manufacturing of components used in the chemical processing field. Inconel 625 can also be used in the nuclear field to manufacture components for the reactor core and control rods in the nuclear water reactors.
Inconel 718 is a precipitation-hardenable nickel-chromium alloy containing significant amounts of iron, niobium, molybdenum, and lesser amounts of aluminum and titanium. This also makes Inconel expensive. Inconel 718 is non-magnetic. It has outstanding weldability including resistance to post-weld cracking, and has corrosion resistance and high strength, where other Inconel alloys are difficult to weld due to brittleness and cracking at the exact welding point. Inconel 718 has a high nickel content, which gives the alloy a relatively strong resistance to chloride stress cracking corrosion. Inconel 718 is a valuable metal used for the most demanding conditions due to its properties, but it also makes this material expensive.
Passivation is recommended to strengthen the corrosion resistance properties of Inconel after the manufacturing operation is completed.
