A new two-step selective laser remelting of 316L stainless steel: process, density, surface roughness, mechanical properties, microstructure

Lu, Ping; Zhang, Chenglin; Haiyi, Liang; Wang, Liang; Liu, Tong

doi:10.1088/2053-1591/ab8b86

Cited by 14 publications

(6 citation statements)

References 20 publications

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“…In this study, printability refers to successfully building apart, and concurrently avoiding or minimizing macrocracking defects and delamination. Lu et al (2020) and Zhang et al (2019) have reported that in their studies, when remelting was done at a different angle than the first scanning, with NiTi elementally blended powders, when changing the direction of remelting, the laser collects welding contaminations on the part surface. That collection of contaminations causes surface roughness and porosity.…”

Section: Resultsmentioning

confidence: 99%

Laser powder bed fusion (LPBF) of NiTi alloy using elemental powders: the influence of remelting on printability and microstructure

Chmielewska

Wysocki

Gadalińska

et al. 2022

RPJ

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Purpose The purpose of this paper is to investigate the effect of remelting each layer on the homogeneity of nickel-titanium (NiTi) parts fabricated from elemental nickel and titanium powders using laser powder bed fusion (LPBF). In addition, the influence of manufacturing parameters and different melting strategies, including multiple cycles of remelting, on printability and macro defects, such as pore and crack formation, have been investigated. Design/methodology/approach An LPBF process was used to manufacture NiTi alloy from elementally blended powders and was evaluated with the use of a remelting scanning strategy to improve the homogeneity of fabricated specimens. Furthermore, both single melt and up to two remeltings were used. Findings The results indicate that remelting can be beneficial for density improvement as well as chemical and phase composition homogenization. Backscattered electron mode in scanning electron microscope showed a reduction in the presence of unmixed Ni and Ti elemental powders in response to increasing the number of remelts. The microhardness values of NiTi parts for the different numbers of melts studied were similar and ranged from 487 to 495 HV. Nevertheless, it was observed that measurement error decreases as the number of remelts increases, suggesting an increase in chemical and phase composition homogeneity. However, X-ray diffraction analysis revealed the presence of multiple phases regardless of the number of melt runs. Originality/value For the first time, to the best of the authors’ knowledge, elementally blended NiTi powders were fabricated via LPBF using remelting scanning strategies.

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Section: Resultsmentioning

confidence: 99%

Laser powder bed fusion (LPBF) of NiTi alloy using elemental powders: the influence of remelting on printability and microstructure

Chmielewska

Wysocki

Gadalińska

et al. 2022

RPJ

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“…In addition, it was interesting to find that that the temperature increased again in Point D. This is mainly due to the influence of heat transfer on the first-pass molten pool during the second-pass melting molten pool, and the maximum temperature increases to 1200℃(less than 1357.77℃), which avoids the remelting of the firstpass molten track and the grain growth [19][20][21]. Therefore, laser process parameters (hatching space 0.08 mm) meet the requirements of overlapping rate and non-remelting.…”

Section: Temperature Flowmentioning

confidence: 99%

Molten pool structure and temperature flow behavior of green-laser powder bed fusion pure copper

Zhang

Liu

et al. 2022

Mater. Res. Express

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Additive Manufacturing(AM) is an advanced direct-manufacturing technology, based on the discrete-stacking principle. Laser Powder Bed Fusion (L-PBF) is one of the most promising technologies in the field of metal AM, with the characteristics of fabricating parts with complex shapes directly. For L-PBF equipment , the core device is lasers, and almost all L-PBF printers are currently equipped with infrared laser. However, due to too low absorption rate of the pure copper surface to infrared laser and high thermal conductivity between pure copper, it is extremely challenging to fabricate pure copper by traditional infrared-laser powder bed fusion(IR L-PFB). In this work, green-laser was applied to replace traditional infrared laser during L-PBF process, molten pool structure and temperature flow behavior of Green-Laser powder bed additive manufacturing pure copper was studied by mesoscopic simulation. Here we show that green-laser greatly improved the absorption rate of the pure copper surface, and the result showed that with lower cost laser process parameters (lower laser power 300W and larger hatching space 0.08 mm), pure copper parts with smoother surface, no-remelting and no obvious defects could be fabricated successfully.

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“…The relationship between volumetric energy density and defects (pores, bubbles and cracks, etc) of 316L stainless steel has been systematically studied by authors in [9,10]: Too low or too high volumetric energy density will lead to balling. Low volumetric energy density leads to incomplete melting or even no-melting of metal powder, resulting in pores; excessive volumetric energy density resulted in liquid metal splashing, bubbles and even cracks.…”

Section: Mesoscopic Numerical Model For L-pbf Processmentioning

confidence: 99%

Mesoscopic numerical simulation and experimental investigation of laser powder bed fusion AlCu5MnCdVA alloys

Lu¹,

Zhang²,

Liu³

et al. 2021

Mater. Res. Express

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AlCu5MnCdVA alloys had high specific strength, good machining and fatigue properties, outstanding electroplating and excellent corrosion resistance. However, due to wide crystallization temperature range, it is hard to realize sequential solidification for AlCu5MnCdVA alloy by traditional casting process. Laser Powder Bed Fusion (L-PBF) has become one of the most promising technology in Metal Additive Manufacturing (MAM). In this study, L-PBF was employed to fabricate AlCu5MnCdVA parts, and both mesoscopic numerical element model and experimental printing were applied to study the feasibility of L-PBF Additive Manufacturing AlCu5MnCdVA alloy. Relative densities, phase analysis and micromorphology were investigated systematically by SEM, EDS and XRD. The laser process parameters window for AlCu5MnCdVA were obtained: volumetric energy density 41–51 J mm−3, laser power 230–240W, laser scanning speed 1200–1325 mm s−1. And the relative density of parts fabricated by L-PBF reached 96.1%. Besides, AlCu5MnCdVA alloy fabricated by L-PBF was mainly consist of α-Al, little other phase such as Al2Cu or Al2Mn3 was detected.

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A new two-step selective laser remelting of 316L stainless steel: process, density, surface roughness, mechanical properties, microstructure

Cited by 14 publications

References 20 publications

Laser powder bed fusion (LPBF) of NiTi alloy using elemental powders: the influence of remelting on printability and microstructure

Laser powder bed fusion (LPBF) of NiTi alloy using elemental powders: the influence of remelting on printability and microstructure

Molten pool structure and temperature flow behavior of green-laser powder bed fusion pure copper

Mesoscopic numerical simulation and experimental investigation of laser powder bed fusion AlCu5MnCdVA alloys

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