Thermo-mechano-metallurgical modeling of the wire arc additive manufacturing of titanium alloy parts

The multiple benefits offered by Wire Arc additive manufacturing (WAAM) have led to a growing interest in this technology. This applies to the manufacturing of titanium alloy components for aerospace or naval fields, where there is a need for more efficient methods for the production of large and complex parts. Direct Energy Deposition processes such as WAAM involve important heating and cooling cycles which induce complex physical phenomena. The current lack of understanding of these phenomena and the lack of control of the process parameters can lead to the formation of defects like porosity in the parts and the development of residual stresses and distortions which could affect strongly the mechanical properties. To overcome this problem in the case of titanium alloy parts manufacturing, the development of a thermo-mechano-metallurgical modeling is proposed. Based on the previous work of El Cheikh in 2012 and Theodore in 2023, a disk model is adapted to the WAAM process and material (Ti-6Al-4V alloy) used in this study to predict the geometry of the deposits as a function of manufacturing parameters (i.e., wire feed speed, welding speed, voltage and current). An original equivalent volumetric heat source model is also developed based on Goldak’s double ellipsoid distribution. The use of this equivalent heat source coupled with the finite element method gives relevant information on the temperature distribution, the thermal gradients, and the geometry of the welding pool during the manufacturing. To validate the thermal modeling, a 30 layers Ti-6Al-4V wall has been deposited with temperature monitoring through thermocouple measurements and compared to the simulations. The obtained results will further constitute inputs for metallurgical and mechanical modeling and eventually enable the optimization of the WAAM process in order to produce parts with higher quality.