Microstructure Evolution and Epitaxial Growth Characteristics of Droplet and Arc Deposition Additive Manufacturing for Aluminum Alloy
GENG Ruwei1(), WANG Lin2, WEI Zhengying3(), MA Ninshu4
1 School of Mechanical and Electrical Engineering, China University of Mining and Technology, Xuzhou 221116, China 2 School of Materials Science and Physics, China University of Mining and Technology, Xuzhou 221116, China 3 State Key Laboratory for Manufacturing System Engineering, Xi'an Jiaotong University, Xi'an 710049, China 4 Joining and Welding Research Institute, Osaka University, Osaka 567-0047, Japan
Cite this article:
GENG Ruwei, WANG Lin, WEI Zhengying, MA Ninshu. Microstructure Evolution and Epitaxial Growth Characteristics of Droplet and Arc Deposition Additive Manufacturing for Aluminum Alloy. Acta Metall Sin, 2024, 60(11): 1584-1594.
Aluminum alloys are widely used in the automobile, rail transportation, and aerospace industries owing to their excellent properties such as low density, high thermal conductivity, and high specific strength. Metal additive manufacturing (MAM) enables the high-quality integrated forming of aluminum alloy components. Among the MAM techniques, droplet and arc additive manufacturing (DAAM) is a newly proposed method that offers advantages, such as high efficiency and low cost. In DAAM process, a droplet generation system is designed above the substrate fixed on a three-dimensional motion platform. Below the droplet generation system, an arc heat source with variable polarity is tilted. During the DAAM process, the metal droplets drop vertically and sequentially into the molten pool generated by the arc heat source to realize metallurgical bonding. Layer-by-layer deposition of aluminum alloy components is achieved by moving the substrate. This study focuses on the DAAM process for 2319 aluminum alloy. The temperature field distribution, microstructure evolution, and epitaxial growth characteristics were investigated. First, the temperature field distribution during the deposition process was calculated using the finite element method combined with element birth and death techniques. Based on the temperature field analysis, the solidification parameters at different positions of the molten pool were calculated. These parameters were then substituted into a phase field (PF) model to determine the growth and evolution of the microstructure at different positions in the molten pool. Columnar crystal structures were formed in the bottom and middle regions of the molten pool. From the bottom to the upper part of the molten pool, the temperature gradient decreased and the solidification speed increased. Therefore, columnar crystals to equiaxed transition occurred in the middle and upper regions. Additionally, misorientation angles were introduced in the PF model to investigate the epitaxial growth characteristics of the solidification process. Larger misorientation angles had a more obvious influence on dendrite morphology and were more likely to be eliminated during competitive growth. Finally, the metallographic analysis showed that from the bottom to the upper part of the deposition layer, the microstructure changed from columnar to equiaxed crystals, and the presence of columnar crystal epitaxial growth agreed well with the simulation results.
Fund: National Natural Science Foundation of China(52205432);National Natural Science Foundation of China(52275376);China Postdoctoral Science Foundation(2022M723375);Natural Science Foundation of Jiangsu Province(BK20221118);Natural Science Foundation of Shandong Province(ZR2023QE232)
Fig.1 Schematic of droplet and arc additive manufacturing (DAAM) process (a) and experimental platform (b) (Vs—substrate moment velocity, GTA—tungsten inert gas)
Fig.2 Temperature (T)-dependent physical properties of 2319 aluminum alloy
Fig.3 Initial conditions of epitaxial growth phase field model (θ0—misorientation angle)
Fig.4 Temperature field distributions of deposition layer under currents of 220 A (a), 240 A (b), and 260 A (c); and temperature change curves at the center point of the layer under different currents (d) (G—temperature gradient)
Fig.5 Temperature gradient and solidification velocity distribution in the molten pool (V—solidification speed; inset shows the temperature field, and two blue arrows represent the projection process of the selected points on the fusion line)
Fig.6 Microstructure growth processes at the bottom (a-c) and the middle part (d-f) of molten pool (c— concentration, c∞—concentration far away from the interface, c / c∞—relative concentration, t—time, Δt—time step. One grid size is 0.216 μm) (a) t = 2500Δt (b) t = 8500Δt (c) t = 24500Δt (d) t = 2500Δt (e) t = 8500Δt (f) t = 19500Δt
Fig.7 Columnar to equiaxed transition (CET) processes during solidification showing the microscopic microstructure growths (a-c) and corresponding temperature field distributions (d-f) at different time (ΔT—undercooling) (a, d) t = 5100Δt (b, e) t = 5700Δt (c, f) t = 6700Δt
Fig.8 Relationship between micromorphology and solidification conditions of grains (For an alloy of a given composition, the morphology and size of the grains are mainly determined by G and V in the molten pool)
Fig.9 Growth processes of solidification microstructure at the misorientation angles of 20° (a-c), 30° (d-f), and 40° (g-i) (ΔZ is the grain height difference with different misorientation angles) (a, d, g) t = 2500Δt (b, e, h) t = 7500Δt (c, f, i) t = 12500Δt
Fig.10 Deposition layer (a) and cross-sectional morphology (b) obtained by droplet and arc additive manufacturing
Fig.11 Microscopic structures of the deposition layer at different positions (a) bottom (zone A in Fig.10b) (b) middle (zone B in Fig.10b) (c) upper part (zone C in Fig.10b)
Fig.12 Epitaxial characteristics of dendrite growth
1
Wu D J, Liu D H, Zhang Z A, et al. Microstructure and mechanical properties of 2024 aluminum alloy prepared by wire arc additive manufacturing [J]. Acta Metall. Sin., 2023, 59: 767
doi: 10.11900/0412.1961.2021.00314
Li Q, Wang F D, Wang G Q, et al. Wire and arc additive manufacturing of lightweight metal components in aeronautics and astronautics [J]. Aeron. Manuf. Technol., 2018, 61(3): 74
Wang H M. Materials' fundamental issues of laser additive manufacturing for high-performance large metallic components [J]. Acta Astronaut., 2014, 35: 2690
Gu D D, Zhang H M, Chen H Y, et al. Laser additive manufacturing of high-performance metallic aerospace components [J]. Chin. J. Lasers, 2020, 47: 0500002
Xiao W J, Xu Y X, Song L J. Phase-field study on the evolution of microstructure of the molten pool for additive manufacturing [J]. Chin. J. Theor. Appl. Mech., 2021, 53(12): 11
Francois M M, Sun A, King W E, et al. Modeling of additive manufacturing processes for metals: Challenges and opportunities [J]. Curr. Opin. Solid State Mater. Sci., 2017, 21: 198
8
Derekar K S. A review of wire arc additive manufacturing and advances in wire arc additive manufacturing of aluminium [J]. Mater. Sci. Technol., 2018, 34: 895
9
Wang L, Wei Y H, Yu F Y, et al. Phase-field simulation of dendrite growth under forced flow conditions in an Al-Cu welding molten pool [J]. Cryst. Res. Technol., 2016, 51: 602
10
Yu F Y, Wei Y H, Ji Y Z, et al. Phase field modeling of solidification microstructure evolution during welding [J]. J. Mater. Process. Technol., 2018, 255: 285
11
Geng R W, Du J, Wei Z Y, et al. Multiscale modelling of microstructure, micro-segregation, and local mechanical properties of Al-Cu alloys in wire and arc additive manufacturing [J]. Addit. Manuf., 2020, 36: 101735
12
Wang L, Ma Y M, Xu J. Numerical simulation of arc-droplet-weld pool behaviors during the external magnetic field-assisted MIG welding-brazing of aluminum to steel [J] Int. J. Therm. Sci., 2023, 194: 108530.
13
Zheng M, Wei L, Chen J, et al. A novel method for the molten pool and porosity formation modelling in selective laser melting [J]. Int. J. Heat Mass Transfer, 2019, 140: 1091
14
Zhang W B, Chen W, Chen D L, et al. Multi-scale numerical simulation of molten pool evolution process for electron beam selective melting [J]. Chin. J. Nonferrous Met., 2023, 33: 1413
Bayat M, Dong W, Thorborg J, et al. A review of multi-scale and multi-physics simulations of metal additive manufacturing processes with focus on modeling strategies [J]. Addit. Manuf., 2021, 47: 102278
16
Du J, Wu Y X, Jiang M B, et al. Molten pool dynamics and particle migration Behavior during TIG-assisted droplet deposition manufacturing of SiC particle-reinforced aluminum matrix composites [J]. J. Mech. Eng., 2023, 59(3): 318
doi: 10.3901/JME.2023.03.318
He P F, Wei Z Y, Du J, et al. Investigation of droplet + arc deposition additive manufacturing with WCP simultaneous reinforcement for aluminum alloy [J]. J. Mech. Eng., 2022, 58(5): 258
Michaleris P. Modeling metal deposition in heat transfer analyses of additive manufacturing processes [J]. Finite Elem. Anal. Des., 2014, 86: 51
19
Goldak J, Chakravarti A, Bibby M. A new finite element model for welding heat sources [J]. Metall. Trans., 1984, 15B: 299
20
Salerno G, Bennett C, Sun W, et al. On the interaction between welding residual stresses: A numerical and experimental investigation [J]. Int. J. Mech. Sci., 2018, 144: 654
21
Ramirez J C, Beckermann C, Karma A, et al. Phase-field modeling of binary alloy solidification with coupled heat and solute diffusion [J]. Phys. Rev., 2004, 69E: 051607
22
Echebarria B, Folch R, Karma A, et al. Quantitative phase-field model of alloy solidification [J]. Phys. Rev., 2004, 70E: 061604
23
Kang H, Song S J, Sul Y E, et al. Epitaxial-growth-induced junction welding of silver nanowire network electrodes [J]. ACS Nano, 2018, 12: 4894
doi: 10.1021/acsnano.8b01900
pmid: 29709175
24
Yu Y, Wang L, Zhou J, et al. Impact of fluid flow on the dendrite growth and the formation of new grains in additive [J]. Addit. Manuf., 2022, 55: 102832
25
Deschamps J, Georgelin M, Pocheau A. Growth directions of microstructures in directional solidification of crystalline materials [J]. Phys. Rev., 2008, 78E: 011605
26
Park J, Kang J H, Oh C S. Phase-field simulations and microstructural analysis of epitaxial growth during rapid solidification of additively manufactured AlSi10Mg alloy [J]. Mater. Des., 2020, 195: 108985
27
Wang J C, Guo C W, Li J J, et al. Recent progresses in competitive grain growth during directional solidification [J]. Acta Metall Sin, 2018, 54: 657
doi: 10.11900/0412.1961.2017.00543
Dong H B, Lee P D. Simulation of the columnar-to-equiaxed transition in directionally solidified Al-Cu alloys [J]. Acta Mater., 2005, 53: 659
29
Li H G, Huang Y J, Jiang S S, et al. Columnar to equiaxed transition in additively manufactured CoCrFeMnNi high entropy alloy [J]. Mater. Des., 2021, 197: 109262
30
Lenart R, Eshraghi M. Modeling columnar to equiaxed transition in directional solidification of Inconel 718 alloy [J]. Comput. Mater. Sci., 2020, 172: 109374
31
Yang M, Wang L, Yan W T. Phase-field modeling of grain evolutions in additive manufacturing from nucleation, growth, to coarsening [J]. npj Comput. Mater., 2021, 7: 56
32
Gao Y M. Principle of Metal Solidification [M]. Xi'an: Xi'an Jiaotong University Press, 2010: 72
