They are trade names, not chemistries. Inconel covers nickel-chromium grades, Hastelloy covers both nickel-molybdenum and nickel-chromium-molybdenum grades, and Monel is nickel-copper. Each name maps to a UNS number, a DIN number and a GB designation.
What each name actually covers
Inconel began as a Huntington Alloys trademark for nickel-chromium alloys, and it now spans 718, 625, 600, 601, 617, X-750, 602CA and the cast grade 713C. Most are hardened either by solid solution or by the gamma-prime and gamma-double-prime precipitates.
Hastelloy is a Haynes name covering two distinct branches. The B family (B2, B3) is nickel-molybdenum and handles reducing acids. The C family (C276, C22) is nickel-chromium-molybdenum and handles oxidising and reducing media in the same vessel. X is a third branch: nickel-chromium-iron-molybdenum for high-temperature oxidation rather than aqueous corrosion.
Monel is nickel-copper. 400 is the workhorse for seawater and hydrofluoric acid; K-500 is the age-hardened version with roughly twice the strength.
Why the name on the drawing is not enough
Because a trade name is a family, not a grade. An enquiry that says only 'Hastelloy' can mean C276 or B3, and those two are not interchangeable: one is specified for oxidising media, the other for reducing, and a substitution in the wrong direction fails in service rather than on the certificate.
Every grade we list carries its UNS number, its DIN number and, where one exists, its GB designation. Quoting against the UNS number removes the ambiguity entirely.
The two other families on our list
Nimonic is nickel-cobalt-chromium, precipitation hardened, and appears in turbine and high-temperature spring work. Precision alloys are the controlled-expansion and soft-magnetic grades — Invar, Kovar and their relatives — which are bought for thermal expansion or permeability rather than for corrosion.
All six families are stocked or melted as bar, plate, strip, seamless tube and forgings, so the family name only decides which table you look at, never what we can supply.