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Inconel Alloy 718

Inconel Alloy 718

INCONEL® alloy 718 (UNS N07718/W.Nr. 2.4668) is a high-strength, corrosion-resistant nickel chromium material used at -423° to 1300°F. The age-hardenable alloy can be readily fabricated, even into complex parts. Its welding characteristics,especially its resistance to postweld cracking, are outstanding. The ease and economy with which INCONEL alloy 718 can be fabricated, combined with good tensile, fatigue, creep, and rupture strength, have resulted in its use in a wide range of applications. Examples of these are components for liquid fueled rockets, rings, casings and various formed sheet metal parts for aircraft and land-based gas turbine engines, and cryogenic tankage. It is also used for fasteners and instrumentation parts.

Physical Properties

Density, lb/in3
Annealed…………………………..0.296
Annealed and Aged …………………..0.297
Melting Range, °F……………………..2300-2437
Melting Range,°C ……………………..1260-1336
Specific Heat at 70°F, Btu/lb °F (at 21°C, J/kg °C) ……..0.104 (435)
Curie Temperature, °F (°C)
Annealed Material……………………………………….<-320 (<-196)
Annealed and Aged Material ………………………..-170 (-112)
Permeability at 200 oersted and 70°F
Annealed Material………………………………………….1.0013
Annealed and Aged Material …………………………..1.0011

Chemical Composition

Nickel (plus Cobalt) ………………….50.00-55.00
Chromium………………………………..7.00-21.00
Iron ………………………………………..Balance*
Niobium (plus Tantalum)…………..4.75-5.50
Molybdenum …………………………….2.80-3.30
Titanium…………………………………..0.65-1.15
Aluminum ………………………………..0.20-0.80
Cobalt ………………………………………1.00 max.
Carbon………………………………………0.08 max.
Manganese ………………………………..0.35 max.
Silicon ………………………………………0.35 max.
Phosphorus………………………………..0.015 max.
Sulfur…………………………………………0.015 max.
Boron ………………………………………..0.006 max.
Copper……………………………………….0.30 max.

Designation & Standards

INCONEL alloy 718 is designated at UNS N07718, UNS N07719, and Werkstoff Nr. 2.4668. It is listed in NACE MR01-75 for oil and gas service. Alloy 718 is available as pipe, tube, sheet, strip, plate, round bar, flat bar, forging stock, hexagon, wire and extruded section

Plate, Sheet, and Strip: ASTM B 670, ASTM B 906,ASME SB 670, ASME SB 906, SAE AMS 5596, SAE AMS 5597, SAE AMS 5950, AECMA PrEN 2407,AECMA PrEN 2408, ISO 6208, DIN 17750

Bar, Rod, Wire, and Forgings: ASTM B 637, ASME SB 637, SAE AMS 5662, SAE AMS 5663, SAE AMS 5664, SAE AMS 5832, SAE AMS 5914, SAE AMS 5962, ASME Code Case 1993, ASME Code Case 2206, ASME Code Case 2222, AECMA PrEN 2404, AECMA PrEN 2405, AECMA PrEN 2952, AECMA PrEN 2961, AECMA PrEN 3219, AECMA PrEN 3666, ISO 9723, ISO 9724, ISO 9725, DIN 17752-17754

Pipe and Tube: SAE AMS 5589, SAE AMS 5590, ASME Code Case N-253, DIN 17751

Welding Products– INCONEL Filler Metal 718 – AWS 5.14 / ERNiFeCr-2

Other Products –ASME Code Case N-62, ASME Code Case N208, DIN 17744

Applications
  • Based on its high-temperature resistance up to 700 °C (1,300 °F), its excellent oxidation and corrosion resistance, and its good workability,  Alloy 718 is used in many demanding applications. Originally, it was developed and used for static and rotating components in aircraft turbines such as housings, mounting elements and turbine disks, where tough requirements apply for creep resistance and fatigue behavior, in particular for the rotating applications.
  • Due to its properties, its good workability and efficiency, the material is additionally widely used for static and rotating components in stationary gas turbines, rocket drives and spacecraft, motor vehicle turbo chargers, high-strength screws,springs and mounting elements, and for heat-resistant tools in forgeries, extruders and separating shearers.
  • The variant ® Alloy 718 CTP, which is laid out specifically for the requirements of the oil and gas industry, finds increasing uses in drilling equipment and pump shafts. The components used must ensure an efficient and safe oil and gas extraction with increasing drilling hole depth and pressures and temperatures becoming more critical, and withstand the acid gas environment (H2S, CO2, chloride) that is prevalent there (see special data sheet Alloy 718 CTP).