Microstructure, mechanical properties, residual stresses and texture analysis of Ti-5Al-2.5Sn alloy weldments obtained using electron beam of different oscillation patterns

Electron beam welding was used for welding of Ti-5Al-2.5Sn alloy using three types of beam oscillation patterns, i.e. elliptical, concentric circles and arrow shape waveform. The influence of these patterns on microstructure, mechanical properties and residual stresses was investigated using optical microscopy, electron back scattered diffraction, scanning electron microscopy, microhardness measurement, residual stress measurement, impact testing, smooth and notch tensile testing. A partial martensitic transformation was observed in the fusion zone of all the three welding patterns. The fusion zone of arrow pattern weldment exhibited approximately 16% and 1.2% higher hardness than elliptical and concentric circles patterns, respectively. Owing to an improved texture of the basal and prismatic planes in the cross-weld direction, the arrow pattern showed improved strength, reduced tensile residual stresses than elliptical and concentric circles pattern. Elliptical pattern showed superior elongation characteristics as well as increased impact strength as compared to the arrow and concentric circle patterns.