Characterisation of porosity, density, and microstructure of directed energy deposited stainless steel AISI 316L

Tan, ZhiEn Eddie; Pang, J.H.L.; Kaminski, Jacek K; Pepin, Helene

doi:10.1016/j.addma.2018.11.014

Cited by 54 publications

(39 citation statements)

References 29 publications

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“…The DLD/LENS process can be used to produce near-net shaped components or treat damaged or worn areas of a component [8]. The DLD/LENS technology has proved to be effective to fabricate a wide range of materials including stainless steels, titanium, nickel-base super alloys and cobalt-base alloys, etc [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

On the origin of the high tensile strength and ductility of additively manufactured 316L stainless steel: Multiscale investigation

Barkia

Aubry

Haghi-Ashtiani

et al. 2020

Journal of Materials Science & Technology

132

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We report that 316L austenitic stainless steel fabricated by direct laser deposition (DLD), an additive manufacturing (AM) process, have a higher yield strength than that of conventional 316L while keeping high ductility. More interestingly, no clear anisotropy in tensile properties was observed between the building and the scanning direction of the 3D printed steel. Metallographic examination of the as-built parts shows a heterogeneous solidification cellular microstructure. Transmission electron microscopy observations coupled with Energy Dispersive X-ray Spectrometry (EDS) reveal the presence of chemical micro-segregation correlated with high dislocation density at cell boundaries as well as the in-situ formation of well-dispersed oxides and transition-metal-rich precipitates. The hierarchical heterogeneous microstructure in the AM parts induces excellent strength of the 316L stainless steel while the low staking fault energy of the as-built 316L promotes the occurrence of abundant deformation twinning, in the origin of the high ductility of the AM steel. Without additional post-process treatments, the AM 316L proves that it can be used as a structural material or component for repair in mechanical construction.

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Section: Introductionmentioning

confidence: 99%

On the origin of the high tensile strength and ductility of additively manufactured 316L stainless steel: Multiscale investigation

Barkia

Aubry

Haghi-Ashtiani

et al. 2020

Journal of Materials Science & Technology

132

View full text Add to dashboard Cite

show abstract

“…At first, they found that according to the chemical composition of the material and the Schäffler diagram, the estimated δ-ferrite content of the columnar boundary lies in the region of 20% δ-ferrite. The Creq and Nieq of their DED AISI 316L suggest that the solidification of their material falls within the upper range of the austenitic-ferritic mode in such a way that an austenitic steel forms a predominantly austenitic microstructure with columnar δ-ferrite along the solidification direction ( Figure 11) [41]. The δ-ferrite phase can be recognized by the higher Cr and Mo content.…”

Section: Appl Sci 2020 10 X For Peer Review 10 Of 23mentioning

confidence: 99%

“…However, it is reported that this diagram is not an exact diagram and, thus, the outcome is an approximation of the final δ-ferrite content [69]. Zhi'En et al also studied the solidification mode of the AISI 316L alloy according to the role of alloying elements [41]. In their work, it is shown that by changing the ferrite stabilizer or austenite stabilizer content the solidification mode is different and, consequently, the final alloy can be either duplex or fully austenitic (Figure 9b).…”

Section: Appl Sci 2020 10 X For Peer Review 6 Of 23mentioning

confidence: 99%

“…Terrassa et al studied the role of hatch rotation angle on the built quality of DED AISI 316L samples [40]. Tan et al examined the correlation between the porosity, density, and microstructure of AISI 316L samples produced via DED technology [41]. However, it should be highlighted that according to the existing body of literature on the processing of AISI 316L stainless steel via the DED process, microstructure and mechanical properties analyses are the dominant features that have been considered in the previous research ( Figure 2).…”

Section: Introductionmentioning

confidence: 99%

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Microstructure and Mechanical Properties of AISI 316L Produced by Directed Energy Deposition-Based Additive Manufacturing: A Review

et al. 2020

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Directed energy deposition (DED) as a metal additive manufacturing technology can be used to produce or repair complex shape parts in a layer-wise process using powder or wire. Thanks to its advantages in the fabrication of net-shape and functionally graded components, DED could attract significant interest in the production of high-value parts for different engineering applications. Nevertheless, the industrialization of this technology remains challenging, mainly because of the lack of knowledge regarding the microstructure and mechanical characteristics of as-built parts, as well as the trustworthiness/durability of engineering parts produced by the DED process. Hence, this paper reviews the published data about the microstructure and mechanical performance of DED AISI 316L stainless steel. The data show that building conditions play key roles in the determination of the microstructure and mechanical characteristics of the final components produced via DED. Moreover, this review article sheds light on the major advancements and challenges in the production of AISI 316L parts by the DED process. In addition, it is found that in spite of different investigations carried out on the optimization of process parameters, further research efforts into the production of AISI 316L components via DED technology is required.

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“…Various process parameters used during the additive manufacturing of SS316L have been examined [4,5]. One of the important outputs are the mechanical properties [6,7] or porosity [8]. The building direction also plays a vital role [9], and the final surface roughness is of particular interest [10].…”

Section: Introductionmentioning

confidence: 99%

Monotonic Tension-Torsion Experiments and FE Modeling on Notched Specimens Produced by SLM Technology from SS316L

et al. 2020

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The aim of this work was to monitor the mechanical behavior of 316L stainless steel produced by 3D printing in the vertical direction. The material was tested in the “as printed” state. Digital Image Correlation measurements were used for 4 types of notched specimens. The behavior of these specimens under monotonic loading was investigated in two loading paths: tension and torsion. Based on the experimental data, two yield criteria were used in the finite element analyses. Von Mises criterion and Hill criterion were applied, together with the nonlinear isotropic hardening rule of Voce. Subsequently, the load-deformation responses of simulations and experiments were compared. Results of the Hill criterion show better correlation with experimental data. The numerical study shows that taking into account the difference in yield stress in the horizontal direction of printing plays a crucial role for modeling of notched geometries loaded in the vertical direction of printing. Ductility of 3D printed specimens in the “as printed” state is also compared with 3D printed machined specimens and specimens produced by conventional methods. “As printed” specimens have 2/3 lower ductility than specimens produced by a conventional production method. Machining of “as printed” specimens does not affect the yield stress, but a significant reduction of ductility was observed due to microcracks arising from the pores as a microscopic surface study showed.

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Characterisation of porosity, density, and microstructure of directed energy deposited stainless steel AISI 316L

Cited by 54 publications

References 29 publications

On the origin of the high tensile strength and ductility of additively manufactured 316L stainless steel: Multiscale investigation

On the origin of the high tensile strength and ductility of additively manufactured 316L stainless steel: Multiscale investigation

Microstructure and Mechanical Properties of AISI 316L Produced by Directed Energy Deposition-Based Additive Manufacturing: A Review

Monotonic Tension-Torsion Experiments and FE Modeling on Notched Specimens Produced by SLM Technology from SS316L

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