Multi-layer deposition mechanism in ultra high-frequency pulsed wire arc additive manufacturing (WAAM) of NiTi shape memory alloys

W. C. Ke, João Pedro Oliveira, B. Q. Cong, S. S. Ao, Z. W. Qi, Bei Peng, Zhi Zeng

Research output: Contribution to journalArticlepeer-review

44 Citations (Scopus)

Abstract

Ultra high-frequency pulsed gas tungsten arc welding (UHFP-GTAW)-based Wire Arc Additive Manufacturing (WAAM) was used to fabricate thin walls of NiTi shape memory alloys. The transient heat and fluid flow are critical during fusion-based additive manufacturing, since they impact the as-built microstructure. In this work, a three-dimensional numerical model, which includes the force, surface Gauss heat source and periodic droplet transfer models, was developed to simulate the deposition of 5 layers. The gravity, buoyancy, electromagnetic, surface tension, arc pressure and arc shear stress are considered in the developed force model. An improved free surface tracing method using the volume of fluid (VOF) technique was proposed to more effectively track the free surface of the molten pool with the computational fluid dynamics (CFD) software FLUENT. The multiphysics phenomena associated to the process, namely the temperature and velocity fields of the molten pool, were studied. The model was then validated by experiments. It is revealed that the microstructure of the as-built parts is refined by the UHFP current power which induces significant vibration of the molten pool. These findings lay the foundations for optimizing the WAAM process aiming at fabricating high quality and complex NiTi parts.

Original languageEnglish
Article number102513
JournalAdditive Manufacturing
Volume50
DOIs
Publication statusPublished - Feb 2022

Keywords

  • Computational fluid dynamics (CFD)
  • Droplet transfer
  • NiTi shape memory alloy
  • Ultra high-frequency pulsed GTAW (UHFP-GTAW)
  • WAAM

Fingerprint

Dive into the research topics of 'Multi-layer deposition mechanism in ultra high-frequency pulsed wire arc additive manufacturing (WAAM) of NiTi shape memory alloys'. Together they form a unique fingerprint.

Cite this