Complete dissolution of gamma prime via severe plastic deformation in a precipitation-hardened nickel-base superalloy

Abstract

Abstract The effect of multiple friction stir processing on suppressing liquation cracking of a cast precipitation-hardened nickel-base superalloy was investigated. The severe plastic deformation and simultaneous high temperature with rapid cooling resulted in dramatic changes of the liquation-cracking-related microstructures: high volume fraction gamma prime precipitations were completely dissolved into the matrix, carbide dendrites were fully disintegrated and matrix grain size was remarkably refined to submicron scale. These modifications significantly improved ductility of heat-affected zone and effectively decreased grain boundary liquation simultaneously, thus liquation cracking was completely suppressed in laser surface remelting.