Linear Friction Welding of Ti-64 and Ti-5553 for Aerostructure Applications

The increasing trend to light-weighting new aircraft builds leads to a significant demand for titanium alloy structural parts. The rising material costs and popularity, together with their restrictions in supply and processing, is driving the aerospace industry to make increasingly efficient use of available material.

Linear Friction Welding (LFW), a rapid, high integrity, solid-state forging process, has the potential to decrease the buy-to-fly ratio, production time and time to market of aerostructure components. It has already proven its dependability for the production of some of the latest generation aero engines.

The LFW process is not yet used for aerostructures. This is primarily due to the LFW process not being widely known, and not having been developed or proven for aerostructure applications; but also due to a lack of performance data on aerostructures manufactured by LFW being currently available to the aerostructure supply chain and design community.

This presentation focuses on the results coming from two successive large series of trials. First, over 200 Ti-64 (Ti-6Al-4V) weldments were produced and assessed via metallographic examinations and mechanical testing. The matrix of experiments was able to capture the LFW process window of this titanium alloy, and to measure the impact of the parametric conditions. Second, these findings were transferred to Ti-5553 (Ti-5Al-5V-5Mo-3Cr) for Landing gear applications. Both efforts showed that these welds resulted in high integrity joints free from contaminants and oxides at the weld interface.