Nickel is an austenitic stabilizer. Austenitic stainless steels are a type of stainless steel that contain high levels of nickel and chromium. These steels are known for their excellent corrosion resistance, high ductility, and good formability. Nickel is an important alloying element in austenitic stainless steels, and it plays a key role in stabilizing the austenite phase at room temperature.

Austenite is a face-centered cubic crystal structure that is stable at high temperatures. However, at room temperature, it can transform into other crystal structures, such as ferrite or martensite. This transformation can result in a decrease in the mechanical properties and corrosion resistance of the stainless steel.

Nickel helps to prevent this transformation by stabilizing the austenite phase at room temperature. It does this by forming a solid solution with the iron matrix, which prevents the formation of other crystal structures. This solid solution also increases the strength and toughness of the stainless steel.

Nickel also enhances the corrosion resistance of austenitic stainless steels. It forms a passive oxide layer on the surface of the steel, which acts as a barrier against corrosion. This oxide layer is self-healing and can repair itself if damaged, providing long-term protection against corrosion.

In addition to nickel, chromium is another important alloying element in austenitic stainless steels. Chromium forms a protective oxide layer on the surface of the steel, similar to nickel. However, chromium is not an austenitic stabilizer. It primarily improves the corrosion resistance and oxidation resistance of the steel.

Tungsten and molybdenum are not typically used as alloying elements in austenitic stainless steels. Tungsten is commonly used in high-speed steels and tool steels, where it enhances the hardness and wear resistance. Molybdenum is often added to stainless steels to improve their corrosion resistance in aggressive environments, such as seawater or acidic solutions. However, neither tungsten nor molybdenum has a stabilizing effect on the austenite phase.