Metal transfer in wire feeding-based electron beam 3D printing: Modes, dynamics, and transition criterion

Hu, Renzhi; Chen, Xin; Yang, Guang; Gong, Shuili; Pang, Shengyong

doi:10.1016/j.ijheatmasstransfer.2018.06.033

Cited by 54 publications

(7 citation statements)

References 31 publications

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“…For the wire-feed AM, the heat and mass transferring process from the feed wire to the melting pool is very complicated. Hu et al [33] reported that it is enormously computational-cost consuming to reproduce the process exactly. In this research, we adopt a phenomenological heat source to simplify the calculation.…”

Section: Simulation Methodsmentioning

confidence: 99%

Simulation of solidified β grain for Ti–6Al–4V during wire laser additive manufacturing by three-dimensional cellular automaton method

Sun

Shan

Zong

et al. 2021

Modelling Simul. Mater. Sci. Eng.

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The β grain of Ti–6Al–4V during wire laser additive manufacturing (WLAM) is notorious for its coarse grains and thus reducing the mechanical performance. In this research, to predict and further control the microstructure, three-dimensional (3D) β grain evolution is simulated by 3D cellular automaton method coupled with the transient thermal profile calculated from processing modeling. Simulations are validated by experiments. The competitive growth between grains shows that the grain growth rate is less than the isotherm moving velocity, leading to a flat S–L interface, which in turn makes the orientation plays a more important role than the undercooling. It interprets the phenomena that Ti–6Al–4V grains with ⟨001⟩ orientation along the building direction are preferred during WLAM. Effects of processing parameters on microstructure, such as the deposited layer, the laser power, the inter-layer time and the preheating temperature of substrate, are also investigated. Results show that the grain size at the horizon plane increases with the increase of the deposited layer, the laser power and the preheating temperature, while inter-layer time has few effects on the β grain evolution. 3D grain simulation of additive manufacturing shows promising prospect in predicting the microstructure, revealing underlying mechanisms and optimizing processing parameters.

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Section: Simulation Methodsmentioning

confidence: 99%

Simulation of solidified β grain for Ti–6Al–4V during wire laser additive manufacturing by three-dimensional cellular automaton method

Sun

Shan

Zong

et al. 2021

Modelling Simul. Mater. Sci. Eng.

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“…The volume of fluid (VOF) [22] or TruVOF [23] method and enthalpy-porosity technique [24] were used to track the timedependent liquid-gas interface (free surface) and solid-liquid interface, respectively. The wire movement in the simulation of the wire feed welding process was described by using a mixture theory and Euler method [25,26]. The incompressible thermal fluid flow was described by the three conservation equations of mass, momentum and energy:…”

Section: Fluid Flow Modellingmentioning

confidence: 99%

Control of meltpool shape in laser welding

Suder,

Chen,

Sierra

et al. 2024

Weld World

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In laser welding, the achievement of high productivity and precision is a relatively easy task; however, it is not always obvious how to achieve sound welds without defects. The localised laser energy promotes narrow meltpools with steep thermal gradients, additionally agitated by the vapour plume, which can potentially lead to many instabilities and defects. In the past years, there have been many techniques demonstrated on how to improve the quality and tolerance of laser welding, such as wobble welding or hybrid processes, but to utilise the full potential of lasers, we need to understand how to tailor the laser energy to meet the process and material requirements. Understanding and controlling the melt flow is one of the most important aspects in laser welding. In this work, the outcome of an extensive research programme focused on the understanding of meltpool dynamics and control of bead shape in laser welding is discussed. The results of instrumented experimentation, supported by computational fluid dynamic modelling, give insight into the fundamental aspects of meltpool formation, flow direction, feedstock melting and the likelihood of defect formation in the material upon laser interaction. The work contributes to a better understanding of the existing processes, as well as the development of a new range of process regimes with higher process stability, improved efficiency and higher productivity than standard laser welding. Several examples including ultra-stable keyhole welding and wobble welding and a highly efficient laser wire melting are demonstrated. In addition, the authors present a new welding process, derived from a new concept of the meltpool flow and shape control by dynamic beam shaping. The new process has proven to have many potential advantages in welding, cladding and repair applications.

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“…The model is described in detail elsewhere. [65][66][67][68] In summary, the model considers the liquid metal as a laminar-Newtonian incompressible fluid and uses the volume of fluid (VOF) method to track the time-varying liquid-gas interface (free surface). [66] The enthalpy-porosity technique was used to implicitly track the time-dependent liquid-solid interface (mushy zone).…”

Section: Cfd Process Modelmentioning

confidence: 99%

Achieving a Columnar-to-Equiaxed Transition Through Dendrite Twinning in High Deposition Rate Additively Manufactured Titanium Alloys

Davis,

Wainwright,

Sahu

et al. 2024

Metall Mater Trans A

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The coarse β-grain structures typically found in titanium alloys like Ti–6Al–4V (wt pct, Ti64) and Ti–6Al–2Sn–4Zr–2Mo–0.1Si (Ti6242), produced by high deposition rate additive manufacturing (AM) processes, are detrimental to mechanical performance. Certain modified processing conditions have been shown to lead to a more refined grain structure, which has generally been attributed to a change in the solidification conditions with respect to the experimental Hunt diagram proposed by Semiatin and Kobryn. It is shown that with Wire Arc AM (WAAM) increasing the wire feed speed (WFS) is effective in promoting a columnar-equiaxed transition (CET). Conversely, estimates of the dendrite-tip undercooling using the KGT model suggest that this will be too small for free nucleation without the addition of artificial nucleants, due to the very low solute partitioning in Ti alloys. It is also shown that it is difficult to promote a CET with plasma transferred arc WAAM as computational fluid dynamics (CFD) melt-pool simulations indicate that the solidification parameters remain within the columnar region on the Semiatin-Kobryn Hunt map, within the constraints of a stable process. However, a high fraction of twin boundaries was observed in the refined β-grain structures seen at high WFS. This has been attributed to departure of $$\left\langle {001} \right\rangle _{\beta }$$ 001 β alignment from the direction of maximum thermal gradient, caused by the curvature of the fusion boundary, stimulating dendrite twinning during solidification. In addition, it is shown that increasing the WFS leads to a change in melt-pool geometry and a reduction of remelt depth, which promoted dendrite twinning and grain refinement.

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Metal transfer in wire feeding-based electron beam 3D printing: Modes, dynamics, and transition criterion

Cited by 54 publications

References 31 publications

Simulation of solidified β grain for Ti–6Al–4V during wire laser additive manufacturing by three-dimensional cellular automaton method

Simulation of solidified β grain for Ti–6Al–4V during wire laser additive manufacturing by three-dimensional cellular automaton method

Control of meltpool shape in laser welding

Achieving a Columnar-to-Equiaxed Transition Through Dendrite Twinning in High Deposition Rate Additively Manufactured Titanium Alloys

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