Influence of overlapping process on the distribution of Cr element in laser cladding 316L powder on 45# steel substrate

Abstract

To investigate the influence of the overlapping process on the distribution of Cr during the laser cladding process, a novel three-dimensional melting and solidification model based on the volume-average method coupled with Eulerian-Eulerian multiphase was established to simulate the process of laser cladding on a 45# steel substrate with different overlapping processes of 316 L powders. The reliability of the model was verified by comparing the simulation results with the melt pool morphology and melt flow rate measured by a high-speed camera. The height and depth of melt pool were verified through the cross-sectional metallographic diagram. The deviations of the melt pool height and depth for single-path cladding were 2.49 % and 6.35 %, respectively, while the deviations for overlapping process were 8.26 % and 6.88 %, respectively. The deviations of melt flow rate were 12.8 % for single-path cladding and 10.0 % for overlapping, respectively. The distribution of chromium (Cr) was verified based on the results of energy-dispersive spectroscopy (EDS), which demonstrated the accuracy of the model. The results demonstrate that reducing the overlapping rate during the overlapping process will increase the dilution rate of the second path of the molten cladding layer which in turn will decrease the concentration of Cr in the lapped area. Reverse overlapping, on the other hand, increases the temperature of the molten pool and the flow rate of the melt, resulting in a more homogeneous mixing of the elements within the second path of the cladding layer. This reduces the difference between the elemental concentration in the lapped area and the elemental concentration of the first and second paths of the cladding layer.