Additive manufacturing of metallic components – Process, structure and properties

DebRoy, T.; Wei, Huiliang; Zuback, J.S.; Mukherjee, T.; Elmer, J. W.; Milewski, J.; Beese, Allison M.; Wilson-Heid, Alexander E.; De, A.; Zhang, Wei

doi:10.1016/j.pmatsci.2017.10.001

Cited by 5,049 publications

(1,898 citation statements)

References 559 publications

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“…of the cellular dendrites microstructure of 316 L steel manufactured by LPBF were consistent with previous reports [5][6][7][18][19][20][21][22]. XRD, EBSD, and TEM analysis carried out in the present investigation revealed a fully austenitic structure in the LPBF 316 L steel.…”

Section: Resultssupporting

confidence: 92%

“…According to [27], the new grains also grow along a preferred crystallographic direction. In the case of cubic crystals, it has been shown that the dominating direction of crystal growth is <100>, which is typical for stainless steels, Ni-base alloys, and Al alloys [5,27]. TEM observations in the present investigation confirmed this behavior.…”

Section: Resultssupporting

confidence: 82%

“…Not all newly nucleated colonies had the same color as the adjacent grains in the substrate, meaning that that not all substrate grains satisfied the conditions for epitaxial nucleation. Similar epitaxial nucleation between the layers was observed by EBSD in different AM materials [5][6][7]25,26]. Figure 2c also shows that in many colonies, the orientation in the inner region was generally the same.…”

Section: Resultssupporting

confidence: 75%

“…In the laser powder fusion processes, the cellular or cellular-dendritic mode was not uncommon. This type of microstructure has been observed for different engineering alloys like austenitic steels, aluminum alloys Co-Cr, and nickel base alloys [5][6][7][10][11][12][13][14][15][16][17][18][19][20][21][22] manufactured by laser or electron powder bed fusion methods. At the high solidification rates observed in the PBF processes, a solute-rich boundary layer is built up in front of the solid-liquid interface due to the limited solute atom diffusion in the liquid phase, thus approaching the conditions for constitutional supercooling [27].…”

Section: Influence Of Solidification Conditions On Microstructure Andmentioning

confidence: 95%

“…Colonies that have the best orientation according to Equation (3) will have preferential conditions to continue growing [5,27]. Therefore, within one single layer, the majority of the colonies will have a solidification texture and will grow at a similar angle to the laser scanning direction.…”

Section: Solidification Texturementioning

confidence: 99%

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Microstructure, Solidification Texture, and Thermal Stability of 316 L Stainless Steel Manufactured by Laser Powder Bed Fusion

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This article overviews the scientific results of the microstructural features observed in 316 L stainless steel manufactured by the laser powder bed fusion (LPBF) method obtained by the authors, and discusses the results with respect to the recently published literature. Microscopic features of the LPBF microstructure, i.e., epitaxial nucleation, cellular structure, microsegregation, porosity, competitive colony growth, and solidification texture, were experimentally studied by scanning and transmission electron microscopy, diffraction methods, and atom probe tomography. The influence of laser power and laser scanning speed on the microstructure was discussed in the perspective of governing the microstructure by controlling the process parameters. It was shown that the three-dimensional (3D) zig-zag solidification texture observed in the LPBF 316 L was related to the laser scanning strategy. The thermal stability of the microstructure was investigated under isothermal annealing conditions. It was shown that the cells formed at solidification started to disappear at about 800 • C, and that this process leads to a substantial decrease in hardness. Colony boundaries, nevertheless, were quite stable, and no significant grain growth was observed after heat treatment at 1050 • C. The observed experimental results are discussed with respect to the fundamental knowledge of the solidification processes, and compared with the existing literature data.

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