Fatigue Enhanced Weld Repair of Titanium (Ti) Alloy Integrally Bladed Rotors (IBR) /Blisks

Stewart Research, LLC has developed an electron beam welding control system that allows for CNC programming of fusion and wire build-up welding from within the Unigraphics CAM environment that is ideally suited for IBR repair. Welding parameters such as beam voltage, current, focus, and deflection pattern are generated based on a material database and part geometry to provide optimal weld quality. Post-weld heat-treating can be localized by rapidly scanning the beam over the repaired region of the blade to deliver a highly controlled thermal flux. Adjacent blades are protected from radiant heating with a foil shield, and the disk section is clamped in a water-cooled fixture. EB welding has a long history as a high-quality repair process for traditional titanium blades, and the high degree of process control offered by the new programming environment allows even greater control over fusion zone microstructure and interstitial element content. The high vacuum in the welding chamber can be complemented with an argon backfill to further reduce oxygen levels, eliminating alpha case formation problems during heat-treatment. Stewart Research is licensing the technology to Sciaky, Inc., the primary supplier of EB repair equipment to the aerospace industry, as an option on their existing product line.BENEFITS: The proposed technology will allow for the high-quality weld repair of individual blades on titanium integrally bladed rotors (IBRs) without putting the disk or other blade sections of the IBR through unnecessary thermal cycles. Transfer of the technology through Stewart Research's commercial partner, Sciaky, Inc. will allow repair of military and commercial IBRs to begin by 2007, greatly extending the useful life of these expensive components.