Effect of Combined Direct Current Electric Field and Pulsed Magnetic Field on the Transient Melt Pool in Laser Additive Manufacturing Process.

The application of a pulsed magnetic field (PMF) during a metallurgy solidification process has proven to be an effective method in refining the grain size and improving the mechanical performance of the material. However, fewer works were reported in the realm of laser additive manufacturing (LAM) and the mechanism of grain refinement consequent to the PMF is still unclear. In this work, numerical models were developed to study the thermal-fluid characteristics in the Ti-alloy melt pool generated during the laser scanning process under the effect of a combined direct current (DC) electric field and PMF.

Influence of the thermal-fluid behavior on the microstructure evolution during the process of selective laser melting of Ti6Al4V.

To account for the microstructure evolution corresponding to the changed scanning speed, the thermal-fluid dynamic model of the meltpool during the selective laser melting (SLM) process of Ti6Al4V was established by numerical method to study the thermal characteristics and the melt flow behavior. Results showed that increasing the laser scanning speed would result in a lower peak temperature but a higher heating and cooling rate on the specimen. Both the meltpool size and its duration were reduced with the increased laser scanning velocity.