Plastic deformation and fragmentation of single-crystal pure copper during friction stir welding

The paper shows the regularities of plastic deformation and fragmentation of pure copper single-crystal after friction stir welding. The obtained data indicate a high role of deformation bands formation with changed orientation of crystal lattice along the contour of the stir zone. Near the stir zone, a larger number of deformation bands are also identified, in which fragmentation of the material into separate grains can already be detected. Near the stir zone, material fragmentation is characterized by the predominance of small-angle boundaries and smooth misorientations in the zone of thermomechanical influence, while in the mixing zone—by more angular boundaries.