Effect of aging treatment on the behavior of room temperature tensile of P/M superalloys used for inertia friction welding joints

The behavior of the room temperature tensile of the FGH96 P/M superalloys connected by the inertia friction welding before and after the aging treatment was investigated, and the failure mechanism of the FGH96 P/M superalloys was evaluated. The results show that, for the FGH96 P/M superalloy samples in the as-welded (original) state, the strength of the superalloy samples in the welding line zone (WLZ) and the heat affected zone (HAZ) is lower than that of the parent alloys, and the plastic strain is the largest during the room temperature tensile process, due to the weak comprehensive strengthening effect of γ′ phase and the straight grain boundaries in WLZ and HAZ. Because of the large grain size in HAZ, the weak strengthening effect of grain boundaries, and the lower dislocation density than that of WLZ, the strength of the superalloy samples in HAZ becomes the weakest, where the cracks originate and show a certain plastic characteristic of the fracture. For the FGH96 P/M superalloy samples after the aging treatment, the comprehensive strengthening effect of γ′ phase is improved, due to the coarsening of γ′ phase, the increase of the strengthened phase volume fraction, and the mismatch increase between γ and γ′, compared with the superalloy samples in the as-welded state, the strength of the superalloy samples after the aging treatment in WLZ and HAZ is higher than that of the parent alloys, and the plastic strain of the parent alloys is larger during the room temperature tensile process. The M₂₃C₆ carbide precipitated continuously or semi-continuously weakens the bonding strength of grain boundary in the as-welded state, leading to the sample fracture and showing the characteristic of brittle fracture. The results of microhardness test verify the strength distribution of the FGH96 P/M superalloy samples in the as-welded state and after the aging treatment.