Study on the impact of external magnetic field intensity on droplet behaviour, heat build-up and dimensional accuracy in wire-arc DED

Abstract

Wire-arc directed energy deposition (DED) faced the issue of limited dimensional accuracy. Conventional wire-arc DED methods may require interlayer dwell or offer limited accuracy enhancement. In this study, a custom-made external magnetic field introduction system was used to achieve a hybrid wire-arc DED with magnetic field. The magnetic induction intensity and orientation of the system could be adjustable. By the influence of the magnetic field, the droplet globular transfer occurred rotating and the transfer frequency increased. The thermal build-up of deposited layers increased with the magnetic field intensity. A suitable increase, such as the 7 mT magnetic induction intensity applied, reduced the wetting angle of deposited layers. Hence forming a flat upper surface of deposited layers facilitates subsequent deposition and reduces the risk of sliding. Based on the results of an optical 3D scanning, the use of a 7 mT magnetic field significantly improved the sidewall dimensional accuracy of the wire-arc DED specimens, achieving the aim of near net shape forming.