The Effect of Beam Oscillation Rate on Al Evaporation from a Ti-6Al-4V Alloy in the Electron Beam Melting Process

Abstract

In order to clarify the quantitative effect of the beam oscillation rate on the Al evaporation behavior, small amounts of Ti-6Al-4V alloy were melted in a 30 kW EB furnace. The changes in the temperature on the melt surface, the weight loss and the Al concentration were investigated in this study.
On the basis of the experimental results, a two dimensional unsteady state heat and mass transfer model was developed. The model was used to evaluate the effect of the beam oscillation rate on the temperature behavior and the evaporation reaction during EB process and also discussion was made on the optimum beam scanning rate.
It was clearly shown that the evaporative loss of both Ti and Al could be suppressed by the increase of the beam oscillation rate. With the beam oscillation rate at more than 1.0 Hz, however, this effect could not be observed clearly anymore. Therefore, the optimum beam oscillation rate can be considered to be in the range of 1.0-10.0 Hz.