On the hot isostatic pressing of Inconel 625 structures built using laser powder bed fusion at higher layer thickness

Nayak, S. K.; Jinoop, A. N.; Paul, C. P.; Kumar, Vesangi Anil; Subburaj, Dineshraj; Singh, Rashmi; Bindra, K. S.

doi:10.1007/s00170-022-08960-4

Cited by 8 publications

(3 citation statements)

References 54 publications

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“…The laser direction for polishing was along the length of the workpiece. More details about the system are provided elsewhere [17]. Figure 1b presents a schematic of the modified LPBF system for laser polishing experiments.…”

Section: Methodsmentioning

confidence: 99%

“…X-ray diffraction of the sample surface was performed with the help of Bruker D8 Focus with a step size of 0.02 degrees from 40 to 80 • . The Scherrer equation was used to estimate the crystallite size from the XRD data with different sets of laser polishing parameters [6,17]. In order to measure the melt pool depth, the samples were epoxy-mounted, polished, and etched.…”

Section: Methodsmentioning

confidence: 99%

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Preliminary Parametric Investigations into Macro-Laser Polishing of Laser-Directed Energy Deposition of SS 304L Bulk Structures

Saini,

Arackal Narayanan,

Sinha

et al. 2023

Crystals

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The higher surface roughness of laser-directed energy deposition (LDED)-built components necessitates advanced and sustainable surface quality enhancement techniques like laser polishing. In the present work, a parametric study involving experimental investigation and numerical analysis is conducted to determine the effect of macro-laser polishing on LDED-built SS 304L structures. A thermophysical model is developed to simulate the effect of laser power and scan speed on the melt pool depth of the LDED-built samples. The simulated melt pool depth is compared with experimental results and is found to be in good agreement. Further, the correlation between the melt pool depth and surface behaviour is studied based on shallow surface melting and shallow over-melting mechanisms. A maximum reduction in surface roughness from 21.3 µm to 9 µm (~57%) is achieved with laser polishing, and process parameters’ effect on the surface roughness is investigated. Scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) mapping, and X-ray diffraction (XRD) are used to further characterize the laser-polished surface. SEM-EDS analysis shows that the segregation is more evident in laser-polished samples, while the XRD results indicate the absence of phase change during the process. This study paves the way to a greater understanding of the effect of macro-laser polishing on LDED-built SS 304L structures.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Preliminary Parametric Investigations into Macro-Laser Polishing of Laser-Directed Energy Deposition of SS 304L Bulk Structures

Saini,

Arackal Narayanan,

Sinha

et al. 2023

Crystals

Self Cite

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show abstract

“…Laser polishing experiments are carried out by turning off the powder spreading in LPBF system. More details about the system are provided elsewhere [15]. Figure 1(b) presents the schematic of the LPBF system used for laser polishing experiments.…”

Section: Methodsmentioning

confidence: 99%

Parametric Investigations on Continuous Wave Laser Polishing of Laser Directed Energy Deposited SS 316L Bulk Structures

Saini¹,

Jinoop²,

Sinha³

et al. 2022

Preprint

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Laser Directed Energy Deposition (LDED) based metal additive manufacturing (MAM) built components have higher surface roughness resulting in the need for post-processing treatments. Laser polishing is one of the advanced post-processing techniques gaining significant attention to improve the surface quality of LDED built components. In the present work, the effect of continuous-wave laser polishing on the surface roughness of SS304L specimen manufactured by LDED is investigated. A thermo-physical model is developed to simulate the effect of laser polishing process parameters on the melt pool depth of the LDED built samples. The simulated melt pool depth is compared to experimentally measured melt pool depth and is found to be in good agreement. A maximum reduction of surface roughness from 21.3 µm to 9.0 µm (~ 57%) is achieved with laser polishing and the effect of process parameters on the surface roughness is investigated. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) mapping, and X-ray diffraction (XRD) are used to further characterise the laser polished surface. SEM-EDS analysis shows that the segregation is more evident in laser polished samples and XRD results show no extra peak generation due to laser polishing. The study paves a way to understand the effect of laser polishing on LDED built SS 304L structures.

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Effect of hard and soft re-coater blade on porosity and processability of thin walls and overhangs in laser powder bed fusion additive manufacturing

Reijonen,

Revuelta,

Metsä-Kortelainen

et al. 2023

Int J Adv Manuf Technol

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Spreading powder into thin layers is a fundamental step in the laser powder bed fusion (PBF-LB) additive manufacturing process. This step is called re-coating and it is typically performed using either a hard, soft or brush-type re-coater blade or a rotating roller, depending on the machine brand and model. With such variety in powder spreading approaches, the question arises whether the used re-coater type has a significant effect on the quality of parts produced? In this study, an industrial contact image sensor integrated to the re-coater of a PBF-LB system was used for powder bed quality monitoring. Powder bed images at 21 µm/pixel resolution, 184 mm scanning width and 95 mm/s re-coating speed were acquired. With this, the effect of using either soft (rubber) or hard (steel) re-coater blade on the processability of challenging features such as thin walls and steep overhangs was studied. In addition, porosity and dimensional accuracy of parts produced using either the soft or hard blade was analyzed with X-ray computed tomography. It is shown that when building bulk material without any complex features, both the hard and soft re-coating blade results in extremely low porosity ≤ 0.001% without any issues in the processability. However, when thin walls and overhangs are produced, differences in processability, porosity and dimensional accuracy are observed as a function of re-coater blade and part orientation. This is an important factor in understanding all the significant sources contributing to the variability on quality of parts produced using different PBF-LB machines.

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On the hot isostatic pressing of Inconel 625 structures built using laser powder bed fusion at higher layer thickness

Cited by 8 publications

References 54 publications

Preliminary Parametric Investigations into Macro-Laser Polishing of Laser-Directed Energy Deposition of SS 304L Bulk Structures

Preliminary Parametric Investigations into Macro-Laser Polishing of Laser-Directed Energy Deposition of SS 304L Bulk Structures

Parametric Investigations on Continuous Wave Laser Polishing of Laser Directed Energy Deposited SS 316L Bulk Structures

Effect of hard and soft re-coater blade on porosity and processability of thin walls and overhangs in laser powder bed fusion additive manufacturing

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