For over 50 years, Ti-6Al-4V has been the most commonly used titanium alloy for aerospace fasteners. However, the need to increase the 160-ksi strength limitation and ¾-inch size limitation of Ti-6Al-4V fasteners, combined with the inherent limitation in through hardenability of Ti-6Al-4V, has created interest in other alloys. Additionally, there is a need to eliminate the cadmium plating associated with alloy steel and Cres fasteners. A promising alternative to these materials is high-strength titanium. For several years, Alcoa Fastening System (AFS) has been evaluating the capabilities of emerging titanium alloys for their potential application in high-strength fastener materials. The alloys range from mature (Ti-10-2–3, Beta-C), to relatively new (Ti-555, SP-700), to limited-experience or experimental (VT16-1, LCB).
