Microstructural and texture development in direct laser fabricated IN718

Parimi, Lakshmi Lavanya; Ravi, G.A.; Clark, Dean S.; Attallah, Moataz M.

doi:10.1016/j.matchar.2013.12.012

Cited by 458 publications

(167 citation statements)

References 15 publications

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“…It has been Figure 9a shows the structure of the as SLM-printed IN718 alloy in the center of the cylindrical specimen. A layered disposition of the solidified material can be observed, which is also in agreement with that reported by other researchers [16,18,20]. The selected surface for analysis, with respect to the building direction, is illustrated in the lower right-hand-side corner.…”

Section: Microstructure Of the As-received Powdersupporting

confidence: 90%

“…Most of the powder particles have spherical shape. However this shape might become irregular due to the partially fused small particles, known as satellites, which are attached to bigger particles during the gas atomizing process [18]. A high magnification secondary electron (SE) image of a satellite particle is shown in Figure 1b.…”

Section: Methodsmentioning

confidence: 99%

“…This phase was surprisingly termed as Laves phase by [16,44]; however, it has different chemical composition than (Ni,Cr,Fe) 2 (Nb,Mo,Ti) as reported by [45][46][47]. Laves phase generally forms due to Nb segregation with other alloying elements, such as Ni, Cr and Fe, with a 1:2 ratio, which is different than MC-type carbide of nearly 1:1 ratio [18]. Differences between Laves and carbide phases in terms of composition and morphology were addressed by Parimi et al [18].…”

Section: Phase Analysis Of Heat Treated Specimensmentioning

confidence: 95%

“…Figure 4a demonstrates the powder particles that are mostly spherical with very fine dendritic networks. This network might be a result of the rapid solidification, with a cooling rate of about 100 • C/s [26], during gas atomization process [18,27]. Non-etched powder particles were sectioned and imaged in Figure 4b to perform phase analysis.…”

Section: Microstructure Of the As-received Powdermentioning

confidence: 99%

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Structure, Texture and Phases in 3D Printed IN718 Alloy Subjected to Homogenization and HIP Treatments

Mostafa

Rubio

Braïlovski

et al. 2017

Metals

193

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3D printing results in anisotropy in the microstructure and mechanical properties. The focus of this study is to investigate the structure, texture and phase evolution of the as-printed and heat treated IN718 superalloy. Cylindrical specimens, printed by powder-bed additive manufacturing technique, were subjected to two post-treatments: homogenization (1100 • C, 1 h, furnace cooling) and hot isostatic pressing (HIP) (1160 • C, 100 MPa, 4 h, furnace cooling). The Selective laser melting (SLM) printed microstructure exhibited a columnar architecture, parallel to the building direction, due to the heat flow towards negative z-direction. Whereas, a unique structural morphology was observed in the x-y plane due to different cooling rates resulting from laser beam overlapping. Post-processing treatments reorganized the columnar structure of a strong {002} texture into fine columnar and/or equiaxed grains of random orientations. Equiaxed structure of about 150 µm average grain size, was achieved after homogenization and HIP treatments. Both δ-phase and MC-type brittle carbides, having rough morphologies, were formed at the grain boundaries. Delta-phase formed due to γ -phase dissolution in the γ matrix, while MC-type carbides nucleates grew by diffusion of solute atoms. The presence of (Nb 0.78 Ti 0.22 )C carbide phase, with an fcc structure having a lattice parameter a = 4.43 Å, was revealed using Energy dispersive spectrometer (EDS) and X-ray diffractometer (XRD) analysis. The solidification behavior of IN718 alloy was described to elucidate the evolution of different phases during selective laser melting and post-processing heat treatments of IN718.

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Section: Microstructure Of the As-received Powdersupporting

confidence: 90%

Section: Methodsmentioning

confidence: 99%

Section: Phase Analysis Of Heat Treated Specimensmentioning

confidence: 95%

Section: Microstructure Of the As-received Powdermentioning

confidence: 99%

See 2 more Smart Citations

Structure, Texture and Phases in 3D Printed IN718 Alloy Subjected to Homogenization and HIP Treatments

Mostafa

Rubio

Braïlovski

et al. 2017

Metals

193

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show abstract

“…Inter-dendritic regions of as-printed specimens have been observed to contain the γ strengthening phase [11,13,38,39]. MC-type carbides and Laves phase have also been reported to exist in these regions [12,[18][19][20]. The Laves phase ((Fe, Ni, Cr) 2 (Nb, Ti)) precipitates as a plate-like phase and forms in inter-dendritic regions due to the segregation of Nb and Ti [40,41].…”

Section: Phase Analysis Of Heat-treated Inconel 718mentioning

confidence: 99%

Microstructural and Microhardness Evolution from Homogenization and Hot Isostatic Pressing on Selective Laser Melted Inconel 718: Structure, Texture, and Phases

Seede

Mostafa

Braïlovski

et al. 2018

JMMP

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Abstract:In this work, the microstructure, texture, phases, and microhardness of 45 • printed (with respect to the build direction) homogenized, and hot isostatically pressed (HIP) cylindrical IN718 specimens are investigated. Phase morphology, grain size, microhardness, and crystallographic texture at the bottom of each specimen differ from those of the top due to changes in cooling rate. High cooling rates during the printing process generated a columnar grain structure parallel to the building direction in the as-printed condition with a texture transition from (001) orientation at the bottom of the specimen to (111) orientation towards the specimen top based on EBSD analysis. A mixed columnar and equiaxed grain structure associated with about a 15% reduction in texture is achieved after homogenization treatment. HIP treatment caused significant grain coarsening, and engendered equiaxed grains with an average diameter of 154.8 µm. These treatments promoted the growth of δ-phase (Ni 3 Nb) and MC-type brittle (Ti, Nb)C carbides at grain boundaries. Laves phase (Fe 2 Nb) was also observed in the as-printed and homogenized specimens. Ostwald ripening of (Ti, Nb)C carbides caused excessive grain growth at the bottom of the HIPed IN718 specimens, while smaller grains were observed at their top. Microhardness in the as-fabricated specimens was 236.9 HV and increased in the homogenized specimens by 19.3% to 282.6 HV due to more even distribution of secondary precipitates, and the nucleation of smaller grains. A 36.1% reduction in microhardness to 180.5 HV was found in the HIPed condition due to γ phase dissolution and differences in grain morphology.

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Inconel 625 by Direct Metal Laser Sintering: Effects of the Process Parameters and Heat Treatments on Microstructure and Hardness

et al. 2016

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Microstructural and texture development in direct laser fabricated IN718

Cited by 458 publications

References 15 publications

Structure, Texture and Phases in 3D Printed IN718 Alloy Subjected to Homogenization and HIP Treatments

Structure, Texture and Phases in 3D Printed IN718 Alloy Subjected to Homogenization and HIP Treatments

Microstructural and Microhardness Evolution from Homogenization and Hot Isostatic Pressing on Selective Laser Melted Inconel 718: Structure, Texture, and Phases

Inconel 625 by Direct Metal Laser Sintering: Effects of the Process Parameters and Heat Treatments on Microstructure and Hardness

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