A Review of Titanium Casting Development for the F -22 Raptor

The F-22A Raptor is the first, high performance, fighter to use Ti-6Al-4V titanium investment castings in safety of flight applications.  The last of the Raptor’s will be delivered to the USAF in 2012 and so it is an appropriate time to review the highlights of development work performed and technical challenges faced in the production application of Ti castings on the F-22.  These include understanding the defects associated with the casting process, such as ceramic shell & hard alpha inclusions, porosity and weld defects.  In addition, the methods used to mitigate defects in castings will be discussed including design & analysis considerations, improved detectability face coats and non-destructive inspection techniques.  These aspects will be illustrated via discussion of the design evolution of the largest casting on the F-22, the aft side-of-body joint which underwent several design changes during the F-22 production run and was ultimately converted from a casting to a welded assembly due to the technical issues discussed.  Finally, the presentation will include a discussion of design considerations to improve the likelihood of successful application of titanium castings on critical airframe structures.