Inconel investment castings are fabricated by vacuum induction melting (VIM) barstock followed by hot isostatic pressing (HIP) and age-hardening heat treatment. Inconel alloys possess excellent welding characteristics if required to repair casting defects or for in-service repairs.
Inconel is a trade name owned by Special Metals Corporation. If you specify a part should be made from Inconel you’re asking for one of their products. Other companies make similar super alloys, but they can’t put the Inconel name on them.
“Super alloy” is used to describe a metal that retains its strength as it gets close to its melting point. Non-super alloys like stainless steel become progressively weaker as they get hotter but a super alloy has its full strength when it’s at 90% of its melting temperature.
Inconel has a particular characteristic that makes it extremely useful for oxidizing environments: as it gets hot it forms a passivating oxide layer on the surface. This resists the oxidation that quickly shortens the life of parts made from other alloys.
Super alloys divide into three types, those that are nickel-based, those that are cobalt-based, and a smaller group that are iron-based. Inconel is around 60% nickel, 18% chromium and 19% iron, plus trace amounts of cobalt, molybdenum, aluminum and titanium. The exact proportions are what differentiates the various types of Inconel, and the equivalent super alloys.