Microstructure and residual stress of laser rapid formed Inconel 718 nickel-base superalloy

Liu, Fencheng; Lin, Xin; Yang, Guiling; Song, Ming; Chen, Jing; Huang, Weidong

doi:10.1016/j.optlastec.2010.06.015

Cited by 277 publications

(90 citation statements)

References 7 publications

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“…There is a bimodal grain size population across the bead which was previously reported by Fencheng Liu et al [13]. Generally, a single bead can be divided into three regions (Fig, 9-b): A.…”

Section: Microstructural Characterisation Of the Solid Blockssupporting

confidence: 57%

Direct Laser Fabrication of INCONEL-718: Effects on Distortion and Microstructure

Parimi¹,

Attallah²,

Gebelin³

et al. 2012

Superalloys 2012 (Twelfth International Symposium)

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Limited work is available in the literature on the influence of Direct Laser Fabrication (DLF) on the microstructural homogeneity and the structural integrity (porosity and distortion) of the deposited structures or "builds". These issues are addressed in the current study for Inconel-718 (IN718), focusing on the influence of the tool (deposition) path on the distortion of the substrate, as well as the microstructural development (grain, precipitates and texture). Differing tool paths are shown to have a significant influence on the distortion exhibited; a strategy for optimising the tool paths is suggested. Due to the good weldability of IN718, the builds were crack-free, but there was a minor fraction of volumetric porosity (~0.02), which spatially varied across the build. The microstructural investigations showed that the build has a heterogeneous microstructure, with coarse columnar and equiaxed grains at the bead centre surrounded by fine equiaxed grains at the bead boundary. Electron-Backscattered Diffraction (EBSD) was performed to rationalise the solidification behaviour and texture developed, and any influence of substrate microstructure. It is found that the grain orientation of the substrate has a significant influence on the build as the first few layers are deposited. However, there is no strong texture in the final microstructure. The build displays significant interdendritic segregation which promotes Laves, γ'', Ti and Nb rich carbides and consequently somewhat lower hardness when compared with wrought IN718.

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Section: Microstructural Characterisation Of the Solid Blockssupporting

confidence: 57%

Direct Laser Fabrication of INCONEL-718: Effects on Distortion and Microstructure

Parimi¹,

Attallah²,

Gebelin³

et al. 2012

Superalloys 2012 (Twelfth International Symposium)

View full text Add to dashboard Cite

show abstract

“…Some studies that examined microstructure evolution were those by Liu et al [72], Toda-Caraballo et al [73], Thijs et al [38], Chen et al [74], Mertins et al [56,75] and Vastola et al [76]. Liu et al and Thijs et al examined the residual stress evolution at the microstructure scale using Vickers hardness tests and concluded that the residual stresses within the microstructure were greatest in the overlapping regions between scan tracks, but were heavily dependent on scan speed and heat profile.…”

Section: Materials and Microstructure Modelsmentioning

confidence: 99%

Overhanging Features and the SLM/DMLS Residual Stresses Problem: Review and Future Research Need

2017

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Abstract:A useful and increasingly common additive manufacturing (AM) process is the selective laser melting (SLM) or direct metal laser sintering (DMLS) process. SLM/DMLS can produce full-density metal parts from difficult materials, but it tends to suffer from severe residual stresses introduced during processing. This limits the usefulness and applicability of the process, particularly in the fabrication of parts with delicate overhanging and protruding features. The purpose of this study was to examine the current insight and progress made toward understanding and eliminating the problem in overhanging and protruding structures. To accomplish this, a survey of the literature was undertaken, focusing on process modeling (general, heat transfer, stress and distortion and material models), direct process control (input and environmental control, hardware-in-the-loop monitoring, parameter optimization and post-processing), experiment development (methods for evaluation, optical and mechanical process monitoring, imaging and design-of-experiments), support structure optimization and overhang feature design; approximately 143 published works were examined. The major findings of this study were that a small minority of the literature on SLM/DMLS deals explicitly with the overhanging stress problem, but some fundamental work has been done on the problem. Implications, needs and potential future research directions are discussed in-depth in light of the present review.

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“…Some studies that examined microstructure evolution were those by Liu et al [72], Toda-Caraballo et al [73], Thijs et al [38], Chen et al [74], and Mertins et al [56,75]. Liu et al and Thijs et al examined the residual stress evolution at the microstructure scale using Vickers hardness tests and concluded that the residual stresses within the microstructure were greatest in the overlapping regions between scan tracks, but was heavily dependent on scan speed and heat profile.…”

Section: Materials and Microstructure Modelsmentioning

confidence: 99%

Overhanging Features and the SLM/DMLS Residual Stresses Problem: Review and Future Research Need

Patterson¹,

Messimer²,

Farrington³

2017

Preprint

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A useful and increasingly common additive manufacturing (AM) process is the selective laser melting (SLM) or direct metal laser sintering (DMLS) process. SLM/DMLS can produce fulldensity metal parts from difficult materials, but it tends to suffer from severe residual stresses introduced during processing. This limits the usefulness and applicability of the process, particularly in the fabrication of parts with delicate overhanging and protruding features. The purpose of this study was to examine the current insight and progress made toward understanding and eliminating the problem in overhanging and protruding structures. To accomplish this, a survey of literature was undertaken, focusing on process modeling (general, heat transfer, stress and distortion, and material models), direct process control (input and environmental control, hardware-in-the-loop monitoring, parameter optimization, and post-processing), experiment development (methods for evaluation, optical and mechanical process monitoring, imaging, and design-of-experiments), support structure optimization, and overhang feature design; approximately 140 published works were examined. The major findings of this study were that a small minority of the literature on SLM/DMLS deals explicitly with the overhanging stress problem, but some fundamental work has been done on the problem. Implications, needs, and potential future research directions are discussed in-depth in light of the present review.

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Microstructure and residual stress of laser rapid formed Inconel 718 nickel-base superalloy

Cited by 277 publications

References 7 publications

Direct Laser Fabrication of INCONEL-718: Effects on Distortion and Microstructure

Direct Laser Fabrication of INCONEL-718: Effects on Distortion and Microstructure

Overhanging Features and the SLM/DMLS Residual Stresses Problem: Review and Future Research Need

Overhanging Features and the SLM/DMLS Residual Stresses Problem: Review and Future Research Need

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