F. Panella (Sp), V. Dattoma, University of Lecce (Italy)
Repair methods employed to date, such as TIG (tungsten inert gas) welding, EBW (electron beam welding) and MPW (micro plasma welding) lead to large Heat-Affected Zones and elevated distortions induced in the component. In alternative to the above-stated methods, linear friction welding and Capacitor Discharge Welding provide drastic reductions in the size of the HAZ, assure good mechanical properties and allow elevated dimensional accuracy.
CDW is performed by the means of an high-intensity current flow, produced by the discharge of a capacitor battery; several specimens of Inconel 718 material have been welded with several combinations of the main parameters involved. In particular, the Multipoint contact welding profile has been conceived, in order to improve the geometrical continuity and the joint strength. All the specimens have been machined according to ASTM standards and Static and Fatigue tests at high temperatures have been done to validate the Multipoint CDW Process and to correlate the welding parameters. Different energy input and applied force have been used to weld each specimen type, resulting in extremely variable performances in terms of static strength and total deformation of the welded joint.
The CDW welding process is an extremely complex technology, since is dependent on many factors, but is a promising tool with many technological and structural advantages; Multipoint CDW can be used for repair and production purposes in several mechanical applications. The metallurgy of significant welded specimens has been analysed and the CDW performances have been established according to micro structural studies.
Key words: Capacitor Discharge Welding, Tensile Tests, Fatigue, Metallurgical analysis, Welding parameters, HAZ, Multipoint contact profile
