The Research On The Crystallizing Of Zinc Bath Process In Hot-Dip Galvanizing

Currently, the coating forming mechanism research generally focus on the evaluation and feedback of the results from cooled coating physicochemical performance test. Owing to the lack of basic theory research about layer crystallization process, project implementation is just base on the terminal detection data as the basis of process adjustment, which make the project implementation and research development has certain blindness. When we research the hot-dip coating, the solidification process of theη phase layer impact on the coating structure, that will have great significance to obtain the best quality coating by optimizing the preparation process. Using of computer to simulate the solidification process has achieved significant results both at home and abroad in the field of casting and welding, but there is no complete theory or literature on the crystallizing process of hot-dip galvanized layer at home and abroad.This article embarked from the hot-dip galvanizing process, measured the cooling curve of the pure zinc and zinc alloy at450℃,460℃,530℃firstly, then calculated the corresponding differential curve, and used the thermal analysis method to find out the parameters characteristic values of the thermal analysis solidification in this series temperature. We find that the equiaxed grains of the solidified structures at460℃is more uniform and refined than450℃and530℃through qualitative analysis of metallurgical.Based on the above experiments, the article used the MATLAB language compiled the program that can simulate hot-dip galvanizing η phase layer crystallization process numerical in the two-dimensional plane. The solidification process calculation of macroscopic temperature field by the finite difference method(FDM), the formation of the microstructure used the method of cellular automata (CA), and the one-way coupling calculation with macroscopic heat transfer, established nucleation and growth model zinc. In the microscopic calculation, nucleation based on Gaussian distribution, growth model using KGT model. To effectively reduce the operation time, the macro temperature field simulation and micro structure used two different sets of meshing and time steps, the macro temperature field calculation of one-way coupled to the microstructure to by linear interpolation method. Used the program complied by the MATLAB make the process of hot-dip galvanized layer η phase crystallization visualization, realized the random nucleation and grain competitive grow, the simulation results under different temperature are in accordance with the actual metallographic observation results, validate the correctness of established model of the nucleation and growth. Finally, by changed the parameters of nucleation, discussed the influence of different nucleation density on the solidified structure.Through the above theoretical analysis, experimental comparision and computer numerical simulation, it provided algorithm basis and guidance for the program design and further study of hot-dip galvanized layer crystallization process, and also provided certain reference for the theoretical study of hot-dip galvanized layer crystallization process.