Repair of Thin Sheet Ti-6AI/4V Firewalls Using Laser Welding

Titanium's excellent corrosive resistive properties, high yield stress, and ability to maintain strength when exposed to burning fuel make it a good choice for fire containment structures in rotorcraft. Firewalls inherently have numerous cutouts, ribs, and other geometric features that hamper repair efforts. Repairs to titanium structures commonly involve mechanical removal of damaged areas followed by installation of fastened repair patches. The repairs are often difficult and may create detrimental edge features while generating additional fastener holes in thin sheet materials. New laser based welds that eliminate the need for fastening have been optimized, tested, and reviewed. Welds generated using the new procedure were inspected for metallurgical properties and tested for static properties. Simple uniaxial Ti 6/4 test coupons were used to evaluate the laser welded versus mechanically fastened connections. The laser welded repairs were found to restore full undamaged strength values. While most of the mechanically fastened repairs produced adequate structural properties they could not match the strength of the welded repairs under static loading Advancements in titanium welding using laser based systems have been shown to be a very viable option for thin titanium sheet metal repairs. Repairs that are impractical using mechanically fastened patches were easily repaired using laser welding.