Properties of 316L formed by a 400 W power laser Selective Laser Melting with 250 μm layer thickness

Shi, Wentian; Wang, Peng; Liu, Yude; Hou, Yidong; Han, Guoliang

doi:10.1016/j.powtec.2019.09.059

Cited by 48 publications

(13 citation statements)

References 23 publications

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“…Four processing conditions were selected, detailed in Table 1, henceforth referred to as Sample A, B, C, and D. Typical LPBF powder layer thicknesses range from 20 -100 µm [52], however recent studies have investigated powder layers up to 250 µm for improved build rate [53,54]. 100 µm was selected for this study for the best radiography image quality within the standard operating range.…”

Section: Experimental Build Conditionsmentioning

confidence: 99%

In situ radiographic and ex situ tomographic analysis of pore interactions during multilayer builds in laser powder bed fusion

Sinclair

Leung

Marussi

et al. 2020

Additive Manufacturing

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Porosity and high surface roughness can be detrimental to the mechanical performance of laser powder bed fusion (LPBF) additive manufactured components, potentially resulting in reduced component life. However, the link between powder layer thickness on pore formation and surface undulations in the LPBF parts remains unclear. In this paper, the influence of processing parameters on Ti-6Al-4V additive manufactured thin-wall components are investigated for multilayer builds, using a custom-built process replicator and in situ highspeed synchrotron X-ray imaging. In addition to the formation of initial keyhole pores, the results reveal three pore phenomena in multilayer builds resulting from keyhole melting: (i) healing of the previous layers pores via liquid filling during remelting; (ii) insufficient laser penetration depth to remelt and heal pores; and (iii) pores formed by keyholing which merge with existing pores, increasing the pore size. The results also show that the variation of powder layer thickness influences which pore formation mechanisms take place in multilayer builds.High-resolution X-ray computed tomography images reveal that clusters of pores form at the ends of tracks and when variations in the layer thickness and melt flow cause irregular 2 remelting and track height undulations. Extreme variations in height were found to lead to lack of fusion pores in the trough regions. It is hypothesised that the end of track pores were augmented by soluble gas which is partitioned into the melt pool and swept to track ends, supersaturating during end of track solidification and diffusing into pores increasing their size.

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Section: Experimental Build Conditionsmentioning

confidence: 99%

In situ radiographic and ex situ tomographic analysis of pore interactions during multilayer builds in laser powder bed fusion

Sinclair

Leung

Marussi

et al. 2020

Additive Manufacturing

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“…Serval research studies have demonstrated that a layer thickness between 100 and 250 μm could be used for the L-PBF process to fabricate dense parts with qualified mechanical properties [ 13 , 14 , 15 , 16 , 17 , 18 ]. A building rate up to 12 mm 3 /s could be reached, which is about 10 times larger than the typical L-PBF process [ 16 ].…”

Section: Introductionmentioning

confidence: 99%

Performance of High-Layer-Thickness Ti6Al4V Fabricated by Electron Beam Powder Bed Fusion under Different Accelerating Voltage Values

Liang

et al. 2022

Materials

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The electron beam powder bed fusion (EB-PBF) process is typically carried out using a layer thickness between 50 and 100 μm with the accelerating voltage of 60 kV for the electron beam. This configuration ensures forming accuracy but limits building efficiency. The augmentation of the accelerating voltage enlarges the molten pool due to the rise in penetrability, suggesting that a higher layer thickness can be used. Therefore, the effects of layer thickness and accelerating voltage were investigated simultaneously in this study to explore the feasibility of efficiency improvement. Ti6Al4V was fabricated by EB-PBF using layer thicknesses of 200 and 300 μm. Two accelerating voltage values of 60 and 90 kV were used to study their effects under expanded layer thickness. The results reveal that dense parts with the ultimate tensile strength higher than 950 MPa and elongation higher than 9.5% could be fabricated even if the layer thickness reached 300 μm, resulting in a building rate of up to 30 mm3/s. The expansion of the layer thickness could decrease the minimum bulk energy density needed to fabricate dense parts and increase the α platelet thickness, which improved the energy efficiency. However, expanding layer thickness had a significant negative effect on surface roughness, but it could be improved by applying augmented accelerating voltage.

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“…They also found, in contrast to vertical samples, that the horizontally built samples have greater strength and less plasticity. Shi et al [ 28 ] studied the effect of a LT of 250 μm on the tensile properties and quality effect of the SS 316L L-PBF parts. They found that microstructure, mechanical properties and relative density effects are affected by the processing parameters.…”

Section: Introductionmentioning

confidence: 99%

Investigations on the Effect of Layers’ Thickness and Orientations in the Machining of Additively Manufactured Stainless Steel 316L

et al. 2021

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Laser-powder bed fusion (L-PBF) process is a family of modern technologies, in which functional, complex (3D) parts are formed by selectively melting the metallic powders layer-by-layer based on fusion. The machining of L-PBF parts for improving their quality is a difficult task. This is because different component orientations (L-PBF-layer orientations) produce different quality of machined surface even though the same cutting parameters are applied. In this paper, stainless steel grade SS 316L parts from L-PBF were subjected to the finishing (milling) process to study the effect of part orientations. Furthermore, an attempt is made to suppress the part orientation effect by changing the layer thickness (LT) of the parts during the L-PBF process. L-PBF parts were fabricated with four different layer thicknesses of 30, 60, 80 and 100 μm to see the effect of the LT on the finish milling process. The results showed that the layer thickness of 60 μm has significantly suppressed the part orientation effect as compared to the other three-layer thicknesses of 30, 80 and 100 μm. The milling results showed that the three-layer thickness including 30, 80 and 100 μm presented up to a 34% difference in surface roughness among different part orientations while using the same milling parameters. In contrast, the layer thickness of 60 μm showed uniform surface roughness for the three-part orientations having a variation of 5–17%. Similarly, the three-layer thicknesses 30, 80 and 100 μm showed up to a 25%, 34% and 56% difference of axial force (Fa), feed force (Ff) and radial force (Fr), respectively. On the other hand, the part produced with layer thickness 60 μm showed up to 11%, 25% and 28% difference in cutting force components Fa, Ff and Fr, respectively. The three-layer thicknesses 30, 80 and 100 μm in micro-hardness were found to vary by up to 14.7% for the three-part orientation. Negligible micro-hardness differences of 1.7% were revealed by the parts with LT 60 μm across different part orientations as compared to 6.5–14% variations for the parts with layer thickness of 30, 80 and 100 μm. Moreover, the parts with LT 60 μm showed uniform and superior surface morphology and reduced edge chipping across all the part orientations. This study revealed that the effect of part orientation during milling becomes minimum and improved machined surface integrity is achieved if the L-PBF parts are fabricated with a layer thickness of 60 μm.

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Properties of 316L formed by a 400 W power laser Selective Laser Melting with 250 μm layer thickness

Cited by 48 publications

References 23 publications

In situ radiographic and ex situ tomographic analysis of pore interactions during multilayer builds in laser powder bed fusion

In situ radiographic and ex situ tomographic analysis of pore interactions during multilayer builds in laser powder bed fusion

Performance of High-Layer-Thickness Ti6Al4V Fabricated by Electron Beam Powder Bed Fusion under Different Accelerating Voltage Values

Investigations on the Effect of Layers’ Thickness and Orientations in the Machining of Additively Manufactured Stainless Steel 316L

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