UNS N07720 / Udimet 720 Nickel Alloy

Udimet 720 (UNS N07720) is a high-strength, precipitation-hardening, nickel-base alloy with good oxidation and sulfide corrosion resistance up to 1800°F (982°C).being considered for applications within modern gas turbine aero-engines, e.g. for high integrity rotating components such as high pressure (HP) turbine discs.

 

Udimet 720 is annealed at 1121°C (2050°F) and then cooled in air in a rapid manner.

Standard tooling methods are used for cold working Udimet 720. Usage of plain carbon steels is not recommended as they may produce galling. Galling can be reduced by the usage of soft die materials and heavy duty lubricants. Tooling is recommended in the cold working process to allow liberal radii and clearances.

Welding processes recommended for Udimet 720 include gas-tungsten arc welding, gas metal-arc welding and shielded metal-arc welding. Submerged-arc welding is not recommended as cracks may develop due to the high heat input. This alloy can be welded by the commonly used welding procedures and the welding surfaces should be free from paint, crayon markings or oil.

Capable of being forged as it is ductile.

Conventional methods are used to readily form Udimet 720 that has good ductility. To obtain good forming results a powerful equipment is used along with heavy-duty lubricants. Usage of heavy-duty lubricants is recommended during the cold forming process of this alloy. After the forming process all traces of the lubricant should be cleaned to prevent embrittlement of this alloy at high temperatures.

Can be machined by conventional machining methods and contains higher strength, gumminess and work-hardening qualities. Work-hardening of the alloy before the cutting process and chatter can be minimized by tooling and a heavy duty machining equipment. Usage of water-base coolants is preferred for milling, turning or grinding. Usage of heavy lubricants is preferred for boring, drilling, broaching or tapping operations.

Udimet 720 is treated under four different temperatures to be air-hardened.

Heat for 2 h at 1113°C (2035°F) and cool in air.

Heat for 4 h at 1079°C (1975F) and oil quench.

Heat for 24 h at 649°C (1200°F) and cool in air.

Heat for 8 h at 760°C (1400°F) and cool in air.

Can be age-hardened in the heat-treatment process.

Used for gas turbine hot section components.