Inconel 718 wire- Creep-rupture strength at high-temperature

Inconel 718 wire is a nickel-chromium alloy which can be hardened by precipitation and have creep-rupture strength at high temperatures of about 700 degrees C. This alloy has better mechanical properties at low temperatures than Inconel X-750 and Nimonic 90. Inconel 718 has higher strength than Inconel X-750 and it is also known as Superimphy 718, Pyromet 718, Udimet 718, Nicrofer 5219, Haynes 718 and Supermet 718.

Applications of Inconel 718 wire in various fields such as

·        Springs

·        Nuclear hold down spring and other components

·        Seal rings

·        Gas turbine components

Nickel based superalloys are within the industrial gas turbine (IGT) engine manufacturing industries for meeting the requirements of the hot gas path components. These superalloys are exposed to the severe operating conditions where high temperature creep, ductility, tensile strength and oxidation resistance are required to withstand the loadings imposed. Various nickel based superalloys such as dilute solid solution strengthened alloys, highly alloyed precipitation hardened materials are developed to meet the requirements for high temperature structural performance and environmental resistance.            

Nickel based superalloy components are joined using methods such as electron beam (EB), gas tungsten arc (GTA), laser welding, friction/inertia bonding etc. Weldability is the capacity of a material to be joined under imposed fabrication conditions into a specific, appropriately designed structure and to perform satisfactorily in the intended service providing fitness for purpose with minimal distortion and controlled number of defects. These procedures should be conducted in a cost-effective manner and the process parameters are determined using empirical ways.

Two heat treatments are used for Inconel 718 such as

·        Solution anneal at 1700-1850 degrees F followed by fast cooling in water and precipitation hardening at 1325 degrees F for eight hours, furnace cool to 1150 degrees F, hold at 1150 degrees F for a total aging time of 18 hours followed by air cooling.

·        Solution anneal at 1900-1950 degrees F followed by fast cooling in water and precipitation hardening at 1400 degrees F for 10 hours, furnace cool to 1200 degrees F, hold at 1200 degrees F for a total aging time of 20 hours followed by air cooling.

Standard wire finishes which are available for Inconel 718 are:

·        Grease (round wire only): Drawn in a heavy grease produces an “Ultra bright” finish for decorative applications

·        Extra Clean: (XC) Extra clean is also referred to as “bright annealed” or “bright annealed and cold rolled”

·        Soap (round wire only): Soap is used as a lubricant in the drawing process and is not removed. It acts as a lubricant during customer part forming operation. A soap finish is available in tempered products.

Various forms which are available for Inconel 718 are:

·        Cut to lengths

·        Continuous Coils

·        Precision cutting

Inconel 718 can be hardened by

·        Age Hardening

·        Cold Working

·        Cold Working followed by Age Hardening

Inconel 718 can be cold rolled to obtain the temper properties needed by specific customers or manufacturing requirements.