Manual GTAW of Superalloy Blade Materials Using High Strength Fillers

Nickel-based superalloys are some of the most difficult materials to weld. Exceptional aging characteristics result in susceptibility to strain-age cracking in the heat affected zone and in the weld itself. To overcome the latter situation, filler alloys are commonly used which are much less strain sensitive than the base alloy. Mechanical strength is sacrificed for ductility with these materials thereby limiting the weldable areas of gas turbine components to regions of relatively low operating stresses. Sophisticated automated techniques have been developed to join superalloys using fillers having similar or identical chemistries to the base alloys. These welding methods are expensive compared to manual processes and are limited when the application involves localized repairs in varied locations. This study demonstrates the successful application of a specially developed process for the manual GTAW joining of precipitation-hardening alloys with filler materials of similar composition and properties.