Experimental and numerical simulation studies of the flow characteristics and temperature field of Fe-based powders in extreme high-speed laser cladding

Extreme high-speed laser cladding technology (EHLA) is widely employed in critical parts manufacturing and repairing due to its high efficiency. The appearance and quality of the cladding layer are directly influenced by the powder flow characteristics and the interaction between powder trajectory and laser beam. In order to elaborate Fe-based powder flow characteristics of the EHLA process, this study established a powder flow model with a ring-shaped nozzle using a transient process bidirectional coupling. The accuracy of the powder flow model was verified using a high-speed camera. The results demonstrated that the error between the simulation results and the real-time images was within 10 %, confirming the validity of the powder flow model. The temperature profiles of laser-powder coupled model indicated that the optimal melting effect of Fe-based powder was achieved at a laser power of 1500 W. Moreover, the maximum elevation angle of the powder flow was mainly influenced by the carrier gas and protective gas flow rate. The experimental and simulation results showed that the optimal process was a protective gas flow rate of 40 L/min and a carrier gas flow rate of 7 L/min.