Multi-physics field coupling and microstructure numerical simulation of laser cladding for engine crankshaft based on CA-FE method and experimental study

Abstract

During engine operation, the crankshaft journals are prone to wear, resulting in a decrease in surface matching accuracy and abnormal vibration and noise. Therefore, it is important to strengthen the surface and improve the wear resistance. Laser cladding, which involves multiple disciplines, such as automation control, optics, fluid mechanics, heat transfer, etc., is an effective method. In this paper, based on the finite element method, a numerical model of the laser cladding for the crankshaft journal was established. A disk laser was used to laser clad Fe45 powder on the ASTM1045 substrate. The multi-physics field coupling evolution mechanism of the laser cladding process was quantitatively revealed. The cladding temperature, liquid metal flow rate, and stress are positively correlated with the laser power. Combined with the cellular automata method, the microstructure evolution model during the solidification was established, and the morphology and size distribution of the grains in the cladding layer was obtained. In the middle area of the cladding layer, the grains are mostly columnar and equiaxed crystals. At the same time, the change of material physical parameters with temperature was taken into account in the model, which makes the numerical simulation results more accurate. The numerical simulation results were compared with the experimental results through the microscopic characterization experiment, and the accuracy of the numerical model was verified. Finally, through a friction-wear test, the wear resistance between the cladding layer and the substrate is compared. The average wear amount of the substrate is 1.86mm3 and the average wear amount of the cladding layer is 0.64mm3. The experiment shows that the wear resistance of the cladding layer is higher than that of the substrate, and the wear rate is reduced by 65.59%.