Microstructural Evolution and Mechanical Properties of AA2017 Aluminum Alloy Joints Produced by Rotary Friction Welding and TIG Welding

This study investigates the influence of joining technology on the microstructural evolution and mechanical properties of joints produced from extruded AA2017 aluminum alloy rods. Rotary Friction Welding (RFW) was compared with conventional TIG welding to evaluate the effects of solid-state and fusion-based joining mechanisms. The joints were characterized using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), electron backscatter diffraction (EBSD), hardness measurements, tensile testing, and fracture analysis. TIG welding produced a coarse-grained cast microstructure within the fusion zone, whereas RFW generated a fine-grained microstructure formed through intense thermomechanical deformation accompanied by crystallographic texture evolution. These distinct microstructural characteristics resulted in markedly different mechanical behavior. The RFW joints achieved an ultimate tensile strength of 247 MPa and an elongation to failure of 12.5%, compared with 160 MPa and 1.7%, respectively, for the TIG-welded joints. The results demonstrate that the joint formation mechanism is the primary factor governing the microstructural evolution and mechanical performance of AA2017 alloy joints.