Superplastic Forming of Inconel Alloy 718spf

Superplasticforming (SPF) has become an important manufacturing method for aerospace and fuselage components. The basic reasons for the popularity of this process are reviewed and the compatibilityoffine-grained INCONELB alloy71 8SPF@ to superplasticforming are presented in this paper. The temperature limitations of current aluminum and titanium alloys employed in SPF parts for gas turbine components have prompted the need to find a high temperature nickel-base alloy amenable to current SPF practice and equipment. An optimum temperature, the anticipated flow stresses and preferred strain rates are proposed for INCONEL alloy 718SPF and found to be completely compatible with current SPF equipment now in use by the aerospace industry and their fabricators. The wide use of INCONEL alloy 718SPF (UNS NO771 8) in aerospace applications is based on its high temperature strength and excellent fatigue resistance. These properties must be maintained in any SPF-processed component. Demonstration that these properties are maintained and even exceeded is established using data obtained from a prototype part for a candidate noise suppressor assembly. Finally the influence of INCONEL alloy 718SPF and the SPF method of processing on the design and manufacture of future gas turbine engines is considered and the advantages assessed from the aerospace manufacturers’ viewpoint. @INCONEL and 718SPF@ are trademarks of the Into family of companies. Superalloys 718,625,706 and Various Derivatives Edited by E.A. Loria The Minerals, Metals &Materials Society, 1994