Simulation and Industrial Validation of Molten Pool Morphology and Solidification Structure of Pure Titanium during VAR Process

Change rules of molten pool morphology and solidification structure of Ø980 mm pure titanium ingot during VAR process were studied by using ANSYS and μMatIc softwares.The simulation results show that the molten pool is very small with shallow U type at the arc starting stage,then gradually changes from U to V type.The depth and width of molten pool no longer change in the stable stage of smelting when the equilibrium between heat input and output in the crucible is attained.During the filling process,the molten pool gradually shrinks and disappears.The evolution of solidification structure is that fine crystal structure is formed from the liquid contacted with the crucible wall by rapid cooling,and a part of the fine crystals growing as arborization finally form into columnar crystals with a certain preferential orientation.In the center region of the ingot and the critical region of liquid-solid phase,nucleation and growth of crystals directly occur in the metal liquid,and the formed equiaxed crystals block the growth of columnar crystals coupled with transformation between equiaxed and columnar crystals.By anatomizing the industrial ingot,the simulation results of numerical model are with good accordance with the industrial tests.