Welding of IN792 DS superalloy by electron beam

Ni-based superalloys are widely used in the components of aeronautic engines and gas turbines operating at the highest temperatures. During the service life, surface cracks may form in these mechanical parts; therefore, their repairing by welding is of great technological relevance. Seams have been realized by means of electron beam welding (EBW) on plates of IN792 DS superalloy with material pre-heating. They are free of macro-defects like cracks and pores; however, microstructural changes are observed in molten (MZ) and heat affected (HAZ) zones. The amount of ?' phase in MZ is smaller than that in the base metal, and the particles are very fine with an average size of 20 nm that leads to an increase of hardness. In HAZ particle, coarsening takes place as a consequence of heating; therefore, hardness slightly decreases with respect the base metal. X-ray Photoelectron Spectroscopy analyses carried out inside and outside the MZ, and the results show that the distribution of chemical elements remains homogeneous in the sample. Auger electron spectroscopy line scans with higher lateral resolution evidenced that the center of MZ is depleted of Mo and rich of Cr.