Use of Titanium Castings without a Casting Factor

The Use of Titanium Castings Without a Casting Factor program was conducted to establish A and B allowables for Ti-6Al-4V. Taguchi methods were used to develop a more restrictive chemistry and annealing condition to provide parts with less variability in properties. A and B design allowables that were determined for full scale Ti-6Al-4V missile fins and step plates produced using these new parameters showed very low variability, the standard deviations of these data were less than 2 ksi. The A basis allowables are Ftu125 ski and Fty 120 ksi. A nondestructive inspection technique was developed to correlate measurement of microstructural features to mechanical properties. This was found to be of limited value because of the narrow property band that was established. A new AMS specification that included the new allowables, the microstructural inspection criteria, and the more refined chemistry and post- casting treatments was established for investment cast Ti-6Al-4V. Limited fracture mechanics evaluation was also performed on the cast fins.... Titanium castings, Casting factor, Ti-6AI-4V, Mechanical properties, Design allowables, Specification