Computer Simulation Of Laser Cladding Process With Multi-material And Double Channels

In the process of laser rapid prototyping,laser cladding technology is the most active research hotspot in modern laser processing surface strengthening treatment technology.It has the characteristics of heating speed and cooling speed.It is an effective means to improve the corrosion resistance,wear resistance and oxidation resistance,strength and other performance of the workpiece surface.In the process of laser cladding,the uniformity,stability and controllability of the powder feeding,and the microstructure and properties of the heat-affected zone,and its surrounding heat-affected zone should be ensured.Therefore,the change of the flow field in the nozzle during laser cladding,the transient temperature field and stress field of the matrix during the cladding process are of great significance to the design of the nozzle and the variation of the molten pool in the matrix.In this paper,the aggregation properties of laser cladding coin feed powder powders and the distribution of temperature field and stress field of the substrate were studied.The gas-powder two-phase flow theory and the dual-channel flow are numerically simulated in the flow field of the carrier-type coaxial powder feed nozzle.The trajectories of the powder particles are calculated by using the discrete phase model in FLUENT software.Finally,the laser cladding process is analyzed by the multi-physics field coupling program MPCCI platform: FLUENT uses the standard turbulence model to analyze the flow process in the nozzle;ABAQUS uses the coupled temperature displacement model to simulate the heat transfer process and thermo-mechanical coupling of the substrate by flow-solid-thermal numerical simulation.According to the structural characteristics of the nozzle,the three-dimensional geometrical model of the nozzle is established.First,the shielding gas rate and the particle size of the different sizes are set,the finite element simulation of the flow field is carried out,and obtained the distribution of powder particles mass concentration in the flow field.Secondly,when the flow field height was 20 mm,the flow-solid-heat coupling was calculated and the distribution of the transient temperature field and the stress field in the matrix molten pool was obtained.The results show that the powder particles have the best convergence characteristics from the nozzle distance of 15-20mm;under the condition of other process conditions,the mass flow of the powder particles decreases with the increase of the shielding gas,and the aggregation plane of the powder aggre gation gradually becomes longer,but with the increase of the powder feeding rate,the mass flow rate of the powder particles gradually increases,and the aggregation plane of the powder aggregates is constant.The distribution of the molten pool temperature field is elliptical under the coupling of the multi-physics field,and the temperature field and the stress field change with time to a certain time,and the molten pool of the matrix tends to be stable.