Effects of Marangoni Flow on the Composition Distribution of Laser-Cladded 316L on 45 Steel

During the laser cladding process, complex composition distribution in the molten pool was caused from the Marangoni flow, which leading to one kind of defect termed as macrosegregation. Therefore, comprehensive understanding on the flow behaviors in the molten pool is particularly important for predicting and regulating macrosegregation. In this paper, a three-phase Eulerian model based on the volume averaging method is developed to investigate the effect of Marangoni coefficient variations on the flow and compositional distribution. The flow patterns were photographed and analyzed using a high-speed camera, and then the simulated and experimental results for chromium concentration distribution, size of the cladding layer, depth of the molten pool, and flow pattern were compared and found to be in agreement with each other; thus, the accuracy of the model was validated. Meanwhile, the effects of flow direction and intensity on the composition distribution are comprehensively studied. The results show that the flow direction extremely affects the flow path and evolution process of Cr-enriched melt in the molten pool. At the same time, the flow intensity will change the flow time of Cr-enriched melt in the molten pool and then affect the homogenization of composition distribution.