|
Computer modeling and numerical simulation to establish the link between the material microstructure and material processing, material properties, predict and improve material properties has important engineering and theoretical value. The influence of convection solidification microstructure morphology is unquestionable fact. In this paper, the microstructure of the phase-field method numerical simulation technology, simulation of forced convection subcooled pure metal solidification process of a single dendrite, multi-dendrite growth, dendrite growth under different simulated conditions to explore the cold pure molten metal dendrite growth mechanism. Based on Tong phase-field model development has been the single-phase field control multi-grain phase-field model, phase field, velocity and temperature COUPLED dendrite growth in pure nickel metal solidification process was simulated. Using the Visual C 6.O calculation of the program, in order to improve the computational efficiency and save computation time, the application directly differential to solve the two equations, and then output results. TXT way. Finally, simulation results Tecplot9.0 visualization. First, by analyzing the different single dendritic morphology compared the forced convection case obtained under convection upstream tip of the fastest growth rate, the level of direction, followed by the downstream tip growth slowest; single dendrite at different preferential growth direction of dendritic morphology in the presence or absence of convection and tip speed. Study the case of forced convection without disturbance convection velocity anisotropy coefficient, the undercooling and coupling coefficient of grain morphology, tip velocity calculated under different circumstances. The results showed that: convection dendrite tip growth rate each performance convection velocity, the entire dendrite volume is greater, the upstream dendrite growth velocity the more obvious advantages; anisotropy of the bigger, each to the main branch of the finer anisotropy is greater than 0.07, the the dendritic morphology mutate distortion; undercooling plays a decisive role in the process of pure metal dendrite growth, dendritic tip rate increases linearly with the increase of undercooling trends; as the coupling coefficient increases, the morphology of dendritic by mast - long, thin dendritic, when artificially enlarged grain morphology distortion, therefore, the coupling coefficient of thermal parameters selected by material decision. Again, the analog pure metal without convection multiple grains in the direction of the type of preferential growth morphology, the results show that when the grain grown toward each other, the growth will influence each other, the main branch of the type of grain will be suppressed to each other, such that a grain of a length of the main branch is smaller than the length of the other main branch and the main branch growth bending. Another case of adding noise to promote the growth of the secondary dendrite. In this paper, the computational efficiency is greatly improved, and the more realistic simulation of the solidification process of dendrite growth process.
|