Calculation of flow, heat transfer and evaporation during the electron beam cold hearth melting of Ti-6Al-4V alloy

Abstract:

Electron beam cold hearth melting (EBCHM) is a promising technique for achieving premium titanium alloys for critical rotating parts of the aero-engine and to recycle the titanium scraps. This article studied the heat transfer, the fluid flow and solidification in the cold hearth during EBCHM process of Ti-6Al-4V alloy. The results show that the melt is constrained to a very shallow depth which is 15mm in our experiment and the melt velocity is about a few centimeters per second. The melt temperature increases with the increase of melting power and decreases with the increase of melting rate. The melt depth increases with the increase of melting power, while the effect of melting rate on the shape of melt pool isn’t obvious. The trajectories of inclusions with different densities and sizes were simulated. The density has great influence on the trajectories of particles. The evaporation model was established to study the influence of melting parameters on the ingot composition. The results indicate that melting temperature, melting rate and composition of row materials have great influence on the ingot composition. Round ingots were produced using the commercial EBCHM furnace in the factory. The morphology of the shell was investigated and the ingot composition was tested. The calculating results are in good agreement with experiment.