Circular oscillating laser welding can improve welding quality, but its thermodynamics of the melt pool is not clear. In this study, the basic mechanism during circular oscillating laser welding process was studied by computational fluid dynamics method. The calculation model was verified by experimental results. The results show that the circular oscillating laser reduced the peak temperature and temperature gradient and formed a new vortex in the melt pool. The ascending oscillation frequency and amplitude reduced the temperature gradient and increased the velocity of melt flow significantly. Related mechanisms were revealed at the end. This study proves that circular oscillating laser provides a new way to optimize the laser melting process and have great application values for welding and additive manufactering.

Effects of circular oscillating beam on heat transfer and melt flow of laser melting pool

The investigation of molten pool dynamic behaviors during the “∞” shaped oscillating laser welding of aluminum alloy

Numerical simulations and experiments are conducted to investigate the influence of three different scan paths, namely straight, sine, and cycloid, on the flow dynamics and weld formation during the laser welding of 5A06 aluminum alloys. The cycloid scan path produced molten pools with the largest dimensions, most regular morphology, and lowest temperature gradients. And the shallowest keyhole with the highest stability and the lowest temperature is produced under this condition, which has the effect of reducing and homogenizing the distribution of the fluid velocity. The most complicated vortices are obtained when the cycloid scan path is used. Porosity ratios of 5.5, 4.9, and 0.59 are obtained when the scan paths are straight, sine, and cycloid, respectively. The large and stable molten pool, the shallow keyhole, as well as the low and highly homogeneous melt flow velocity and the complicated vortices, contribute to reduction in porosity formation.

Influence of scan paths on flow dynamics and weld formations during oscillating laser welding of 5A06 aluminum alloy

The suppression mechanism of keyhole-induced porosity of oscillating laser beam welding (OLBW) was investigated via numerical simulation with keyhole dynamics and melt flow. The established model w...

Numerical study of keyhole-induced porosity suppression mechanism in laser welding with beam oscillation

Effects of sinusoidal oscillating laser beam on weld formation, melt flow and grain structure during aluminum alloys lap welding

To solve the problems of poor quality and insufficient joint strength of aluminum alloy weld, a laser scanning welding test platform for aluminum alloy was built. Taking the butt welding of 5052 aluminum alloy with 5 mm and 3 mm thick specimens as the research objects, the study of a “∞”-shaped laser scanning welding process was conducted, and the similarities and differences between the welding process and that of single pass laser welding were compared. The influence of “∞”-shaped laser scanning welding parameters on the weld formation was investigated by the factor variable method. The change of the surface morphology and dynamic evolution of the molten pool was observed by a high-speed camera system. The optimal combination of the welding parameters was obtained by an orthogonal test. The research showed that the “∞”-shaped laser scanning welding pool had good stability and a good weld quality. Under suitable welding parameters, the length and width of the molten pool could be increased significantly compared with those of the single pass laser welding. The growth rate of the length and width could reach 110.19% and 57.69%, respectively. The surface of the weld was evenly distributed with dense fish scales, and the porosity was less than 1%. The tensile strength of the specimen could reach 205.242 MPa, which was 93% that of the base metal; the topography of fracture was full of dimples, and the metallographic structure of the weld was fine and distributed with equiaxed dendrites.

Bin Wang

Papers

Research on the “∞”-shaped laser scanning welding process for aluminum alloy