AMS 5708 is a specification of Nickel Waspaloy, a nickel-base age-hardenable superalloy with excellent high-temperature strength and good corrosion resistance by combustion products.
This specification is available in the form of forgings, bars and rings that are used for parts that require high strength at temperatures up to 1500°F (816°C), such as bolts and turbine blades. The AMS 5708 specification can also be used for oxidation resistance of up to 1750°F (954°C). The heat treatment is as follows:
Solution treatment – melt using vacuum induction method at 1975°F (1079°C), and air cool for 4 hours to produce hardness of 20-25 Rockwell C;
Stabilization – remelt to 1550°F (845°C) using a vacuum arc or electroslug methods, and air cool for 24 hours;
Age harden – reheat to 1400°F (760°C), and air cool for 16 hours to achieve a hardness of 34-40 Rockwell C.
Please note that scale may be formed on the alloy during heat treatment in oxidizing atmospheres. However, this doesn’t affect the properties of the alloy and can be removed by acid pickling or mechanically.
AMS 5708 can be readily welded only in carefully controlled circumstances, using argon-arc methods and the Waspaloy AMS 5828 filler metal. Welds should be avoided in high-stress environments in which this specification is mostly used.
AMS 5708 can be hot worked at 2140-1800°F (1170-980°C), while hydroforming, drawing, spinning, bending, and rolling can be used for cold working.