Inconel 718
Inconel 718 is a precipitation hardening nickel-base alloy designed to exhibit very high yield, tensile and creep rupture properties at temperatures up to 1300°F. Alloy 718's slow aging hardening response allows annealing and welding without spontaneous hardening upon heating and cooling. This alloy has superior weldability compared to nickel-base superalloys hardened with aluminum and titanium. This alloy is used in jet engines and high-speed airframe parts such as wheels, buckets, spacers, high-temperature bolts and fasteners.
Type Analysis
Description
Alloy 718 is a precipitation hardening nickel-base alloy designed to exhibit very high yield, tensile and creep rupture properties at temperatures up to 1300°F. Alloy 718's slow aging hardening response allows annealing and welding without spontaneous hardening upon heating and cooling. This alloy has superior weldability compared to nickel-base superalloys hardened with aluminum and titanium. This alloy is used in jet engines and high-speed airframe parts such as wheels, buckets, spacers, high-temperature bolts and fasteners.
Heat Treatment
To obtain the best combination of tensile and stress rupture properties, the following heat treatments should be used.
1 hour 1750°F to 1800°F (954 to 982°C) air + 8 hours 1325°F (718°C) air 100°F to 1150°F (56°C/hr to 621°C) air, 8 Time keeping and air cooling.
To obtain the best room temperature and cryogenic tensile properties, the following heat treatments should be used:
1 to 2 hours 1950°F (1066°C), air cooled + 8 hours 1325°F (718°C) air cooled 100°F/hr to 1150°F (56°C/hr to 621°C) air cooled , 8 hours holding and air cooling
workability
hot work
Hot work is done using a maximum furnace temperature of 2050°F (1121°C). High temperature cold working in the 1700/1850°F (927/1010°C) range for service temperatures below approximately 1100°F (593°C) will improve the strength of the forging. Long-term soaking at forging temperatures is not recommended. The material should be reduced uniformly to avoid the formation of a double-grained structure.
process
The alloy can be easily machined under annealing or aging hardening conditions. Aging hardening conditions give the chip breaker tool better chip behavior and produce a better finish. Annealed condition slightly longer tool life.
welding
Alloy 718 can be welded by annealing or aging conditions. Welding in the aged condition softens the heat-affected area.
