Effect of severe plastic deformation on grain boundary liquation of a nickel–base superalloy

The effect of severe plastic deformation associated with friction stir processing (FSP) on grain boundary liquation and the attendant cracking of Inconel 738 superalloy was examined. The intense plastic deformation and the associated heat generation during FSP result in a significant change in the relevant microstructural features, such as the size and distribution of secondary phases. These changes provide a liquation-resistant microstructure to the extent required for suppression of grain boundary liquation during laser surface melting.