Effects of different oscillation frequencies on weld morphology, microstructure and fatigue properties of aluminum alloy in adjustable ring welding

Abstract With the advancement of industrial intelligence, laser welding has been increasingly adopted across various sectors. However, aluminum alloy laser welding is prone to weld defects. Previous research has predominantly focused on the effects of oscillation frequency on weld morphology, while limited attention has been paid to its influence on microstructure evolution and fatigue performance. This study investigates the impact of dual-laser beam oscillation frequency on weld quality, fatigue behavior, and the prediction of fatigue limits at 60 Hz and 90 Hz. Thermal simulations revealed the temperature field distribution under different oscillation frequencies. Results indicate that increasing the oscillation frequency elevates heat input at the weld center but reduces it at the weld edges, leading to a decreased depth-to-width ratio of the weld. Mathematical modeling further demonstrated that higher oscillation frequencies enhance fatigue performance, consistent with prior observations linking increased frequencies to improved tensile strength. Notably, at 90 Hz, porosity is significantly reduced, and spherical grain formation is promoted. These microstructural improvements not only enhance static mechanical properties but also extend fatigue resistance. The suppression of porosity and refinement of grain boundaries effectively hinder crack initiation and propagation, thereby elevating the fatigue limit. This study provides critical insights into optimizing oscillation parameters for high-performance aluminum alloy laser welding in intelligent manufacturing applications.