Ultrasonic Enhancement of Vacuum Arc Remelting Process for Dirty White Spot Mitigation

A combined computational/experimental ICME study of ultrasonic application to the vacuum arc remelting (VAR) process for the elimination of dirty white spots (DWS) in Inconel 718 (IN718) is presented. Elimination of DWSs has significant safety, energy, and environmental implications given the criticality of parts manufactured using VAR. The developed phase-field model describes dendrite growth, composition segregation, and the effects of latent heat and wave attenuation on phase transformation. The model parameters have been calibrated against results of additive manufacturing tests. The effects of ultrasound on the solidification have been experimentally observed, quantified, and compared with model predictions. Modal analysis of the solidifying structure during VAR has also been performed. Overall, the major effects of ultrasound on the VAR process were demonstrated to be (i) deceleration of the solidification process and (ii) reduction in droplet adhesion with the wall.