Pre-melted electron beam freeform fabrication additive manufacturing: modeling and numerical simulation

A simulation of heat and mass transfer for a new additive manufacturing method, pre-melted electron beam freeform fabrication, was realized. In this new method, the wire melts inside the diversion nozzle to form a liquid metal, which then flows through the diversion nozzle to transition to the base metal, solidifying and forming. The critical droplet and liquid bridge transition models were established. The critical droplet radius of TC4 is 2.4mm at 1655 celcius and 2.3 mm at 2200 celcius. The correctness of the critical droplet and liquid bridge transition model was verified by the combination of numerical simulations and experiments. The diversion nozzle played a key role in the deposition process, and the slot width had a great influence on the appearance of the deposition. The liquid bridge formed by the liquid metal at the slotted part of the diversion nozzle played the role of 'relay'. The increase in the slot width of the diversion nozzle weakened the drainage and cushioning effect of the nozzle. This paper aims to reveal the deposition process of the new additive manufacturing method and calculate the impact of key process parameters on the deposition process. Provide a simulation model and theoretical basis for subsequent research on this method.