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Family names versus grade names
Inconel, Monel and Hastelloy are trade names used for particular alloy families. Each includes materials with different numbers. Inconel alone does not identify whether 600, 625 or 718 is intended.
A name such as Alloy 625 identifies the numbered alloy generically. Designations such as 2.4856 and UNS N06625 identify it in different systems. Trade name, grade number and standard designation can appear together.
Inconel: different duties within one family
Many alloys known by the Inconel name are nickel–chromium based. 625 is prominent in corrosion-resistant chemical and marine equipment. 718 develops high strength through ageing for engines, turbines, rings and fasteners.
600 and 601 are further options for heated equipment. The oxidation resistance of 601 is important in furnace components. The shared family name does not mean identical properties.
Monel: nickel and copper
Monel 400 and K-500 are nickel–copper alloys for marine parts, pump components and selected chemical equipment. Additional elements in K-500 allow greater strength to develop through ageing.
K-500 is not simply Monel 400 under another number. Components sharing an environment can carry different loads, and the separate alloys address these differing needs.
Hastelloy: familiar chemical-equipment alloys
C-22 and C-276 are Hastelloy options for chemical processes. They provide corrosion resistance in reactors, exchangers, evaporators and line components. Both contain chromium and molybdenum, but in different proportions with different additions.
Neither is superior in every chemical. Temperature and liquid composition can change relative performance. Knowing the complete grade as well as the family name clarifies the material’s properties.
Why are EN and UNS numbers shown together?
Different countries use different designation systems. EN numbers and UNS codes provide identity alongside trade names. 625 and N06625 can identify one alloy in different systems rather than two products.
Similar names are not always identical: C-22 and C-22HS can identify separate alloys. Family name provides context; the complete number clarifies the particular properties.