Capacitor discharge welded bars of Inconel 718 and TiAl6V4 superalloys under fatigue

This work concerns the mechanical behaviour analysis of Capacitor Discharge Welded joints made with Inconel 718 and TiAl6V4 superalloys in the form of cylindrical bars. The research activities have been conducted in the frame of AWFORS project, financed by the European Community. The Capacitor Discharge Welding (CDW) technique is of particular interest for repair processes; it allows the substitution of the damaged part after its removal and the replacement of the new component without consistent additional machining. Good mechanical properties and geometrical integrity are to be achieved; consequently, the multipoint contact profile for the CDW process has been conceived to enhance the microstructural weld characteristics and improve the fatigue and creep behaviour at high temperatures. Fatigue tests have been performed both at room and working temperature, comparing the results between base material and as-welded specimens with the same heat treatment. The microstructure has been deeply analyzed through optic and scanning electron microscope (SEM) observations; this way the microstructural modifications and the Heat Affected Zones have been studied in the welded section as well as the interaction between the weld layers material and the parent metal.