Quantifying the effects of gap on the molten pool and porosity formation in laser butt welding

To obtain a better joint quality in butt welding of aluminum, the gap filling process and quantification effects on molten pool characteristic bubble formation were realized by three-dimensional thermal-mechanistic-fluid coupled model, with consideration heat transfer, fluid flow, phase change recoil pressure. The model was validated synchrotron-radiation result. competition between solidification melting at bottom uncovered to determine morphology. Gap increased loss, tip elongated due filling. Four phenomena appeared sequence initial stage welding: I. filling; II. Frozen; III. Remelt; IV. Bubble formation. result also demonstrated that would disturb pool. In stable growth pool, larger width, greater depth. sharp keyhole depth necking formation, while small fluctuation values resulted from perturbation gap. depends degree flow unique dropping down phenomenon A continuous melt cannot be formed when width beyond 20 μm, which is detrimental quality. These findings are great significance for guiding optimization butt-welding process, such as reducing roughness interface or increasing clamping force reduce