Numerical Simulation Of Temperature Field And Flow Field Of Laser Cladding Powder Flow Pool

Laser cladding is an additive manufacturing technology in which the powder of reinforcement is fused with the base material to form metallurgy by high-energy laser.In the process of laser cladding,there are complex physical phenomena such as the growth of molten pool,the interaction between laser and powder,and the interaction between powder flow and molten pool,which include Marangoni flow,metal solidification and melting,heat and mass transfer,and liquid metal convection in molten pool.Therefore,the molten pool simulation,powder flow simulation and powder flow-molten pool simulation are established,and their interactions are studied and analyzed.A numerical model of molten pool was established to study the thermal history and the variation of molten pool flow during the process of molten pool growth.By changing the laser power and scanning speed,the influence of process parameters on the temperature field and flow field of the molten pool was studied.The results show that the laser power is positively correlated with the maximum temperature and maximum flow velocity of the molten pool.The scanning speed is negatively correlated with the maximum pool temperature,while positively correlated with the maximum pool flow rate.The powder flow model was established to study the temperature field and flow field of the powder flow in the process of laser cladding powder feeding.The results show that when the powder reaches the surface of the matrix,there is the interaction of powder-gas-carrier and laser.The laser power is positively correlated with the maximum temperature of the powder flow,while the powder carrier gas is negatively correlated with the maximum temperature of the powder flow,and positively correlated with the powder flow velocity.The powder concentration is a Gaussian distribution equation,the accuracy of which was R2 =0.9048.The temperature field of powder flow is a Gaussian distribution equation with the accuracy of R2 =0.8623.Based on the pool model,combined with powder concentration distribution equation and powder flow temperature distribution equation as the mass input source of the pool model,a powder flow-pool model was established to study the change of temperature field and flow field of the pool during the growth process of laser cladding.The results show that the temperature field distribution of powder flow-molten pool is basically consistent with the flow field flow relationship in molten pool simulation.The height of the cladding layer is affected by the laser cladding process parameters.The laser power is negatively correlated with the height of the cladding layer,and the influence is smaller than the scanning speed and the powder-gas flow rate.Scanning speed is negatively correlated with the height of cladding layer and has the greatest effect on the height of cladding layer.There is a negative correlation between the powder-gas flow and the height of cladding layer.The temperature field and the growth process of the molten pool in the laser cladding process were tested and verified by using infrared thermometer and high-speed camera,and the morphology of the cladding layer was measured by 3D microscopy system.The results show that the error between the experimental results and the simulation is less than 5%,and the model is accurate and reliable.