Numerical study of aluminum segregation during electron beam cold hearth remelting for large-scale Ti-6 wt%Al-4 wt%V alloy round ingot

Abstract

To investigate aluminum (Al) segregation in industrial-scale Ti-6 wt%Al-4 wt%V (TC4) round ingots produced by electron beam cold hearth remelting (EBCHR), a three-dimensional multiphysics model verified with experimental data in the literature has been established. The numerical predictions qualitatively reveal that the Al concentration distribution in the pool is highly related to the flow pattern. A promising method to restrain Al segregation is to enhance mixing during EBCHR by increasing the casting speed. A series of numerical cases reveal the relation between the casting speed, the dimensionless measure of the stirring intensity (Péclet number, Pe¯), and the corresponding segregation degree (Ф) in the pool. The results suggest that for EBCHR at a pouring temperature 2273 K, as the casting speed increases from 10 to 25 mm/min, the Pe¯ value increases from 418 to 1820, and the corresponding Ф value increases from 0.681 to 0.871. As a consequence, the intensity of aluminum segregation on the solidified cross-section improves (decreases from 2.77 × 10−3 to 1.76 × 10−4).