The evolution of microstructural parameters and mechanical properties of inertia friction welded GH4151

Abstract

The mechanical properties and distribution of microstructural parameters of GH4151 superalloy joined by inertia friction welding (IFW) were investigated in this study. Electron backscattering diffraction (EBSD) was used to characterize γ grain size, size and volume fraction of γ′ particles and stored energy across the weld line. The micro-hardness profiles were measured across the weld line. Significant changes in the microstructure were observed within 2 mm from the weld line since the steep temperature gradient and severe plastic deformation during the IFW process. Moreover, the postweld heat treatment (PWHT) could result in obvious changes in the microstructural parameters, such as coarsening of γ′ particles, dissolution and precipitation of carbides and relief of stored deformation energy. Furthermore, the micro-hardness profiles are influenced by the variation of grain size, γ′ particle size, γ′ volume fraction and the deformation energy stored in the material. This study can serve as a guide for the microstructural optimization and improvement of mechanical properties of IFWed GH4151 superalloy.