Study on the microstructure, mechanical property and residual stress of SLM Inconel-718 alloy manufactured by differing island scanning strategy

Lu, Yanjin; Wu, Songquan; Gan, Yuan; Huang, Ting‐Ting; Yang, Chuanguang; Lin, Jun; Lin, Jinxin

doi:10.1016/j.optlastec.2015.07.009

Cited by 421 publications

(182 citation statements)

References 31 publications

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“…Optimized scanning strategy (i.e., alternating scan direction [99,101], shorter scan length [112], lower scanning speed [112] and re-scanning [109]) can also significantly minimize the residual stress. Specifically, the "island" scanning strategy (i.e., each layer is divided into small islands, within each island the scan vector is alternately forwardand-backward, the vectors in the neighbouring islands are perpendicular to each other, and in the subsequent layer the island pattern is shifted slightly) has shown to effectively decrease the overall residual stress during process [108,113,114].…”

Section: Residual Stressmentioning

confidence: 99%

“…As that for titanium alloys, employing SLM or EBM to manufacture Ni-base superalloys would depend on the specific case or application, since each process has its pros and cons. So far, the Ni-base superalloys applied to SLM are mainly the weldable ones, i.e., IN718 [113,[160][161][162][163][164][165][166][167], IN625 [79,80,168,169], Hastelloy X [170][171][172][173][174], Nimonic 263 [110], which have low additions of both Ti and Al and are less susceptible to strain age cracking. Expansion to the less-weldable Ni-base superalloys has also been attempted, such as IN939 [175], IN100 [176], IN738LC [177][178][179][180][181], CM247LC [114,[182][183][184] and Rene 142 [81].…”

Section: Materials Manufactured With Slmmentioning

confidence: 99%

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Additively Manufactured Inconel 718 : Microstructures and Mechanical Properties

Deng

2018

Linköping Studies in Science and Technology. Licentiate Thesis

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Linköping 2018Cover image: A fracture surface of EBM IN718 after tensile test at room temperature.During the course of research underlying this thesis, Dunyong Deng was enrolled in Agora Materiae, a multidiciplinary doctoral program at Linköping University, Sweden. Printed by LiU-Tryck 2018 © Dunyong Deng AbstractAdditive manufacturing (AM), also known as 3D printing, has gained significant interest in aerospace, energy, automotive and medical industries due to its capabilities of manufacturing components that are either prohibitively costly or impossible to manufacture by conventional processes. Among the various additive manufacturing processes for metallic components, electron beam melting (EBM) and selective laser melting (SLM) are two of the most widely used powder bed based processes, and have shown great potential for manufacturing high-end critical components, such as turbine blades and customized medical implants. The futures of the EBM and SLM are doubtlessly promising, but to fully realize their potentials there are still many challenges to overcome.Inconel 718 (IN718) is a nickel-base superalloy and has impressive combination of good mechanical properties and low cost. Though IN718 is being mostly used as a turbine disk material now, the initial introduction of IN718 was to overcome the poor weldability of superalloys in 1960s, since sluggish precipitation of strengthening phases γ ′ /γ ′′ enables good resistance to strain-age cracking during welding or post weld heat treatment. Given the similarity between AM and welding processes, IN718 has been widely applied to the metallic AM field to facilitate the understandings of process-microstructure-property relationships.The work presented in this licentiate thesis aims to better understand microstructures and mechanical properties EBM and SLM IN718, which have not been systematically investigated. Microstructures of EBM and SLM IN718 have been characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and correlated with the process conditions. Monotonic mechanical properties (e.g., Vickers microhardness and tensile properties) have also been measured and rationalized with regards to the microstructure evolutions before and after heat treatments.For EBM IN718, the results show the microstructure is not homogeneous but dependant on the location in the components, and the anisotropic mechanical properties are probably attributed to alignment of porosities rather than texture.iii Post heat treatment can slightly increase the mechanical strength compared to the as-manufactured condition but does not alter the anisotropy. SLM IN718 shows significantly different microstructure and mechanical properties to EBM IN718. The as-manufactured SLM IN718 has very fine dendritic microstructure and Laves phases in the interdendrites, and is "work-hardened" by the residual strains and dislocations present in the material. Mechanical properties are different between horizontally and vertically built samples, and heat treatment can m...

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Section: Residual Stressmentioning

confidence: 99%

Section: Materials Manufactured With Slmmentioning

confidence: 99%

Additively Manufactured Inconel 718 : Microstructures and Mechanical Properties

Deng

2018

Linköping Studies in Science and Technology. Licentiate Thesis

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“…A fine cellular-dendritic microstructure could be observed in the SLM-fabricated samples as shown in Figure 3. This is a common characteristic for metal materials fabricated by AM processes as a result of the rapid solidification rates in the locally melted areas (selectively laser-scanned regions) which were experienced because of short laser-material interaction time during the build process [25][26][27]. It is well understood that the microstructures obtained in AM-processed metal parts, which depend on the applied processing parameters, strongly influence the mechanical properties of the parts, e.g., the densification levels, yield and tensile strengths and microhardness.…”

Section: Microstructurementioning

confidence: 99%

Investigation on Porosity and Microhardness of 316L Stainless Steel Fabricated by Selective Laser Melting

Yusuf

Chen

Boardman

et al. 2017

Metals

140

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This study investigates the porosity and microhardness of 316L stainless steel samples fabricated by selective laser melting (SLM). The porosity content was measured using the Archimedes method and the advanced X-ray computed tomography (XCT) scan. High densification level (≥99%) with a low average porosity content (~0.82%) were obtained from the Archimedes method. The highest porosity content in the XCT-scanned sample was~0.61. However, the pores in the SLM samples for both cases (optical microscopy and XCT) were not uniformly distributed. The higher average microhardness values in the SLM samples compared to the wrought manufactured counterpart are attributed to the fine microstructures from the localised melting and rapid solidification rate of the SLM process.

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“…Studies have reported the effects of laser power [5,6], scanning speed [6], scanning strategy [7], and laser energy density [5,6] on microstructure and mechanical characteristics of Alloy 718. In SLM-manufactured parts, the desired microstructure is necessarily influenced by complex chemical and physical behaviors through the melt pool as a result of non-equilibrium laser processing technique [8].…”

Section: Introductionmentioning

confidence: 99%

Influence of laser exposure time and point distance on 75-μm-thick layer of selective laser melted Alloy 718

Karimi

Raza

Andersson

et al. 2017

Int J Adv Manuf Technol

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A systematic matrix with 25 samples, using five different point distances and five laser exposure times, depositing 75-μm-thick layers of Alloy 718 has been studied. The work has concentrated on defects formed, hardness of the deposits, and the microstructure. Relatively large amount of defects, both lack of fusion and porosity, was found in several of the specimens in the deposits. The defects were never possible to fully eliminate, but a significant decrease, mainly in the lack of fusion, was seen with increasing laser exposure time. The gas porosity on the other hand was not affected to any larger degree, except for the lowest laser energy input, where a slight increase in porosity was seen. A small increase in hardness was noted with increasing laser energy input. The width of the deposited beads increased with increasing laser energy, while the depth of deposits was more or less constant. However, for the lowest combination of point distance and laser exposure time, quite deep and narrow beads were formed. A comparison was made with deposition of 50-μm-thick layers, with quite similar laser energy input, but with some variation in detailed deposition parameters. It was found that the 75-μm-thick layers contained less lack of fusion, particularly for small point distances. The amount of porosity was also less, but that did not vary with deposition parameters.

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Study on the microstructure, mechanical property and residual stress of SLM Inconel-718 alloy manufactured by differing island scanning strategy

Cited by 421 publications

References 31 publications

Additively Manufactured Inconel 718 : Microstructures and Mechanical Properties

Additively Manufactured Inconel 718 : Microstructures and Mechanical Properties

Investigation on Porosity and Microhardness of 316L Stainless Steel Fabricated by Selective Laser Melting

Influence of laser exposure time and point distance on 75-μm-thick layer of selective laser melted Alloy 718

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