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- Pant, Prabhat, et al.
(författare)
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A study of the influence of novel scan strategies on residual stress and microstructure of L-shaped LPBF IN718 samples
- 2022
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Ingår i: Materials & design. - : Elsevier Ltd. - 0264-1275 .- 1873-4197. ; 214
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Tidskriftsartikel (refereegranskat)abstract
- Process parameters in laser-based powder bed fusion (LBPF) play a vital role in the part quality. In the current study, the influence of different novel scan strategies on residual stress, porosities, microstructure, and crystallographic texture has been investigated for complex L-shape parts made from nickel-based superalloy Inconel 718 (IN718). Four different novel scanning strategies representing total fill, re-melting, and two different sectional scanning strategies, were investigated using neutron diffraction, neutron imaging, and scanning electron microscopy techniques. These results were compared with the corresponding results for an L-shape sample printed with the conventional strategy used for achieving high density and more uniform crystallographic texture. Among these investigated novel strategies, the re-melting strategy yielded approximately a 25% reduction in surface residual stress in comparison to the reference sample. The other two sectional scanning strategies revealed porosities at the interfaces of the sections and due to these lower levels of residual stress were also observed. Also, variation in crystallographic texture was observed with different scan strategies. © 2022 The Author(s)
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| 2. |
- Wilson, Christopher J.L., et al.
(författare)
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Partial melting in polycrystalline ice: pathways identified in 3D neutron tomographic images
- 2024
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Ingår i: Cryosphere. - 1994-0416 .- 1994-0424. ; 18:2, s. 819-836
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Tidskriftsartikel (refereegranskat)abstract
- In frozen cylinders composed of deuterium ice (Tm+3.8C) and 10% water ice (Tm0C), it is possible to track melt pathways produced by increasing the temperature during deformation. Raising the temperature to +2C produces water (H2O) which combines with the D2O ice to form mixtures of HDO. As a consequence of deformation, HDO and H2O meltwater are expelled along conjugate shear bands and as compactional melt segregations. Melt segregations are also associated with high-porosity networks related to the location of transient reaction fronts where the passage of melt-enriched fluids is controlled by the localized ductile yielding and lowering of the effective viscosity. Accompanying the softening, the meltwater also changes and weakens the crystallographic fabric development of the ice. Our observations suggest meltwater-enriched compaction and shear band initiation provide instabilities and the driving force for an enhancement of permeability in terrestrial ice sheets and glaciers.
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