The analysis of asymmetry characteristics during the fiber laser welding of dissimilar materials by numerical simulation

As one of the inevitable trends of the development of advanced manufacturing technology, the diversification of product performance has been achieved in various industries by laser welding of dissimilar materials. However, laser welding of dissimilar materials is still faced with lots of challenges since the welding defects like weld segregation and cracks affect the performance of welded joints greatly. This paper proposes a three-dimensional computational fluid dynamic model to explore the morphology characteristics of weld, distribution homogeneity of alloy compositions in the mixing molten pool and effects of temperature field and flow field under different welding speed conditions in the laser welding of dissimilar materials. The calculated results are compared with the experimental results and good agreement between them has been found. It is indicated that all of the weld profile, temperature field, and flow field are asymmetric, and the alloy compositions are distributed unevenly in the mixing molten pool. With the increase in welding speed, the temperature field and flow field are changed significantly, which results in the variation of weld morphology. Simultaneously, the enhanced fluid convection induced by the lower welding speed is of great importance for the homogeneous distribution of the alloy compositions in the mixing molten pool. The results demonstrate that the proposed model can predict the weld morphology and alloy composition distribution in the fiber laser welding of dissimilar materials.