Simulation Of TC4-DT Alloy Electron Beam Welding Joints Organization Based On Cellular Automaton Method

It is essential for the researches of meso-failure mode of welded joint as well as its failure behavior with the aid of modeling of weld grain structures. By using cellular automaton method, the grain growth of TC4-DT titanium alloy EBW(electron beam welding) joint is simulated.In order to consider the effects of the growth of neighborhood cellular on the centre cellular in the cellular automaton method, the solid fraction and solute distribution algorithms of classical cellular automaton models are modified. The growth of equiaxed grains under uniform temperature field is simulated by using the modified model, which fits well the process of grain growth kinetics. The grain growth indices obtained by the simulation are quite close to theoretical ones. Moreover, good results are also obtained when this model is applied to the simulation of the columnar crystal growth under uniform temperature field.On the basis of researches above, the EBM temperature field for TC4-DT titanium alloy weld is simulated and coupled with cellular automata model, and the simulation of grain morphology of cross section of the weld is accomplished, which shows that a large number of nucleation near the fusion line are formed, and coarse columnar crystals are formed though competitive growth of the grains. Also, the finer the cellular grid, the more accurate the morphology of simulated crystal grains.Finally,the simulated grain structures for the TC4-DT EBW are compared with metallographic ones, which fits well in the number and the morphology of the columnar grain as well as the maximum and minimum size of them.