Heterogeneous Deformation Behaviors of an Inertia Friction Welded Ti2AlNb Joint: an In-situ Study

A defect-free Ti2AlNb joint has been obtained by the inertia friction welding (IFW) technology. The weld zone (WZ) is composed of B2 grains refined discontinuous dynamic recrystallization and enhanced grain refinement strengthening. And average microhardness decreases about 30 HV from WZ to base metal. In-situ SEM analysis reveals that heterogeneous structure causes strong strain partitioning during tensile deformation. microcrack initiation occurs at interface initial phases B2/O boundaries. Owing stress concentration, multi-slip bands cracks tend generate in heat-affected (HAZ), causing a premature fracture.