Formation mechanism of linear friction welded Ti–6Al–4V alloy joint based on microstructure observation

The microstructure of the linear friction welded Ti–6Al–4V titanium alloy joint was investigated by optical microscope, scanning electronic microscope and transmission electron microscope. Results show that the dynamic recovery and recrystallization resulting from the intensive plastic deformation and fast heating and cooling processes during linear friction welding account for the superfine α + β grains in the weld center. Fine α grains distribute in the β matrix or at the boundaries of β grains. A mass of dislocations networks and metastructures present within the α and β grains.