Austenitic stainless steel is one of the five classes of stainless steel by crystalline structure (along with ferritic, martensitic, duplex and precipitation hardened[1]). Its primary crystalline structure is austenite (face-centered cubic) and it prevents steels from being hardenable by heat treatment and makes them essentially non-magnetic.[2] This structure is achieved by adding enough austenite-stabilizing elements such as nickel, manganese and nitrogen.[citation needed] The Incoloy family of alloys belong to the category of super austenitic stainless steels.[3]