Structural response of A286 superalloy to rotary friction welding at different rotation speed

Rotary friction welding was conducted on A286 with a diameter of φ25 mm under 300, 900 and 2100 rpm to understand the structural response of the joint welded at different rotation speeds. Joint morphologies, grain structures inside the morphologies and the corresponding mechanism that governs its formation were characterized and investigated using electron backscattered diffraction (EBSD), which focused on three featured zones located at the center, 1/2R and periphery of the joint. The influence of structural response on joint properties was also investigated. Results show that the morphology of the joint evolves from 'disk shape' to 'near-line shape' and 'scissors shape' as the rotation speed increases from 300 rpm to 2100 rpm. At low rotation speed, refined and recrystallized grains were formed inside disk shape morphologies. Whereas, sub-grains and deformed grains were evolved at the middle (900 rpm) and high (2100 rpm) rotation speed. The recrystallized grains surrounded by the 'disk shape' morphology have a positive effect on the joint strength compared with the sub-grains and deformed grains confined by the 'near-line shape' and 'scissors shape' morphologies.