期刊
ADDITIVE MANUFACTURING
卷 50, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.addma.2021.102513
关键词
WAAM; Computational fluid dynamics (CFD); NiTi shape memory alloy; Ultra high -frequency pulsed GTAW (UHFP; GTAW); Droplet transfer
资金
- National Natural Science Foundation of China [51775091, 52075022, 52175292]
- Science and Technology Project of Sichuan Province [2020ZDZX0015]
- Fundacao para a Ciencia e Tecnologia (FCT) [UIDB/00667/2020]
UHFP-GTAW-WAAM was used to fabricate thin walls of NiTi shape memory alloys. A three-dimensional numerical model was developed to simulate the deposition process, and an improved free surface tracing method was proposed. The study revealed that the vibration of the molten pool induced by UHFP current power can improve the microstructure of the parts.
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.
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