Numerical Simulation and Crack Suppression Study on High-Speed Laser Cladding of ZL101 Aluminum Alloy

To study the influence of high-speed laser cladding process parameters on the quality of aluminum alloy coatings and to predict the tendency of microcracks, this study investigated the temperature distribution and stress–strain of the cladding layer at different laser powers and scanning speeds under the selected process parameters by numerical simulation of the macroscopic temperature field and stress field, as well as by experimental analysis, and observed the influence of the microstructures on the cracks. The results show that when the laser power is 3600 W and the scanning speed is 500 mm/s, the coating stress is minimized, the maximum residual stress is 337.88 MPa, and no microcracks are generated in the experiment. When the scanning speed is 400 mm/s, with the laser power increased from 3400 W to 3800 W, the peak temperature rises, the melt pool size increases, and the maximum equivalent residual stress shows an increasing trend, but the tensile stress along the Y-direction shows a trend of increasing and then decreasing; the laser power is 3600 W, with the scanning rate increased from 300 mm/s to 500 mm/s, the peak temperature. When the laser power is 3600 W, as the scanning rate increases from 300 mm/s to 500 mm/s, the peak temperature decreases, the size of the molten pool decreases, the maximum equivalent stress and the maximum tensile stress along the Y-direction show a tendency to decrease, and with the increase of the number of melting passes, the temperature "superposition effect" occurs. Cracks are easily generated in the bottom center of the coating, and the coarse columnar crystals at the bottom of the molten pool can easily promote the generation and expansion of cracks. Changing the solidification rate of the coating to promote the formation of equiaxial crystals or increase the columnar crystal boundaries increases the resistance to crack expansion and effectively inhibits the crack initiation and expansion along the grain boundaries.