NUMERICAL MODELING OF MAGNETOHYDRODYNAMICS AND SOLIDIFICATION PHENOMENA IN PAM PROCESSED TI-6AL-4V INGOTS

摘要

This paper presents a methodology for modeling and analysis of the interaction between two electromagnetic(EM)fields in a solidifying Ti-6Al-4V(Ti-6-4)ingot processed by the plasma arc cold hearth melting(PAM)process.The two EM fields are generated by the induction coils(stirrer)around the ingot mold and by the plasma torch.This methodology is based on the numerical solution of Maxwell's equations,fluid flow,and heat transfer equations,and modeling of the grain structure.Numerical simulations at the macro-level were conducted using a CFD software.A stochastic model was developed and applied to simulate the grain structure at the mesoscopic level.Simulation results for 5-in and 8-in diameter Ti-6-4 ingots show that the plasma torch and the EM stirrer can have strong effects on both the fluid flow and the solidification structure.A comparison with an experimental grain structure of a 5-in diameter Ti-6-4 ingot is also provided.