Effect of atomization on surface oxide composition in 316L stainless steel powders for additive manufacturing

Riabov, Dmitri; Hryha, Eduard; Rashidi, Masoud; Bengtsson, Sven; Nyborg, Lars

doi:10.1002/sia.6846

Cited by 35 publications

(9 citation statements)

References 37 publications

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“…113 Detailed surface-science studies combining SEM imaging, XPS, and TEM have further shown that the atomizing medium influences the surface oxide chemistry of 316L feedstock powders. 128 Specifically, the effects of vacuum induction melting, inert gas atomization, conventional nitrogen gas atomization, and water atomization on powder surface oxide chemistry were studied. Both sets of gas-atomized powders contained homogeneous Fe 2 O 3 oxide layers roughly 4 nm in thickness alongside other oxide inclusions.…”

Section: Influence Of Lpbf Feedstockmentioning

confidence: 99%

Pitting Corrosion in 316L Stainless Steel Fabricated by Laser Powder Bed Fusion Additive Manufacturing: A Review and Perspective

Voisin

Shi

Zhu

et al. 2022

JOM

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Abstract316L stainless steel (316L SS) is a flagship material for structural applications in corrosive environments, having been extensively studied for decades for its favorable balance between mechanical and corrosion properties. More recently, 316L SS has also proven to have excellent printability when parts are produced with additive manufacturing techniques, notably laser powder bed fusion (LPBF). Because of the harsh thermo-mechanical cycles experienced during rapid solidification and cooling, LPBF processing tends to generate unique microstructures. Strong heterogeneities can be found inside grains, including trapped elements, nano-inclusions, and a high density of dislocations that form the so-called cellular structure. Interestingly, LPBF 316L SS not only exhibits better mechanical properties than its conventionally processed counterpart, but it also usually offers much higher resistance to pitting in chloride solutions. Unfortunately, the complexity of the LPBF microstructures, in addition to process-induced defects, such as porosity and surface roughness, have slowed progress toward linking specific microstructural features to corrosion susceptibility and complicated the development of calibrated simulations of pitting phenomena. The first part of this article is dedicated to an in-depth review of the microstructures found in LPBF 316L SS and their potential effects on the corrosion properties, with an emphasis on pitting resistance. The second part offers a perspective of some relevant modeling techniques available to simulate the corrosion of LPBF 316L SS, including current challenges that should be overcome.

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Section: Influence Of Lpbf Feedstockmentioning

confidence: 99%

Pitting Corrosion in 316L Stainless Steel Fabricated by Laser Powder Bed Fusion Additive Manufacturing: A Review and Perspective

Voisin

Shi

Zhu

et al. 2022

JOM

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“…Recent TEM studies on 316LSS powders fabricated via inert gas atomization 1 , 7 , 24 have revealed the presence of a significant amount of non-oxide precipitates (rich in Mo, Cr, P and S) together with Mn-Si–O precipitates. Interestingly, the maximum cooling rates encountered during inert gas atomization 25 – 27 are in the same range as those occurring during LMD i.e., 10 2 –10 5 K/s, which suggests that there should be a significant presence of non-oxide precipitates in LMD 316LSS.…”

Section: Introductionmentioning

confidence: 99%

Non-oxide precipitates in additively manufactured austenitic stainless steel

Upadhyay

Slama

Gaudez

et al. 2021

Sci Rep

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Precipitates in an austenitic stainless steel fabricated via any Additive Manufacturing (AM), or 3D printing, technique have been widely reported to be only Mn-Si-rich oxides. However, via Transmission Electron Microscopy (TEM) studies on a 316L stainless steel, we show that non-oxide precipitates (intermetallics, sulfides, phosphides and carbides) can also form when the steel is fabricated via Laser Metal Deposition (LMD)—a directed energy deposition-type AM technique. An investigation into their origin is conducted with support from precipitation kinetics and finite element heat transfer simulations. It reveals that non-oxide precipitates form during solidification/cooling at temperatures ≥ 0.75Tm (melting point) and temperature rates ≤ 105 K/s, which is the upper end of the maximum rates encountered during LMD but lower than those encountered during Selective Laser Melting (SLM)—a powder-bed type AM technique. Consequently, non-oxide precipitates should form during LMD, as reported in this work, but not during SLM, in consistency with existing literature.

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“…It should be noted that literature reports on the presence of oxides on the surface of atomized AISI316L powders [ 39 ] : in particular, in inert gas atomized powders (as is the case of this work) Fe 2 O 3 , and Cr, Mn, Si oxides are formed. Oxides should be removed to activate the sintering process, diffusivity being higher for oxides than for pure metals.…”

Section: Resultsmentioning

confidence: 68%

Direct Ink Writing of AISI 316L Dense Parts and Porous Lattices

Biasetto

Elsayed

2022

Adv Eng Mater

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The production of metallic components by additive manufacturing (AM) technologies is today recognized as a standardized method, [1][2][3][4] especially when direct energy deposition (DED) and powder bed fusion (PBF) processes are employed. For instance, AM parts are currently produced by PBF and commercialized by GE Aviation; [5] by 2027 52% revenues of AM are expected to be covered by the aerospace, automotive, and energy sectors. [6] The difference between DED and PBF lies in the powder delivery mechanisms: in DED, the powder can be delivered as is or as a filament and melted on flight by a heat source, in PBF technologies a powder bed is selectively sintered (SLS) or melted (SLM) by a laser or electron beam (EBM). [6] The common points of PBF technologies are the use of micron-size gas atomized powders and the direct melting or sintering of the powders. If this represents an advantage in terms of printable geometries and production time, in contrast, the methods hide several side back effects: the need for a protective atmosphere to avoid oxidation, not all metals or alloy can be melted or sintered by the laser or electron beam power source, during printing hightemperature cooling rates (10 4 -10 5 K s À1 ) are responsible for the formation of metastable microstructures with consequences on the mechanical properties (anisotropy). The powders delivery mechanism does not allow the production of closed hollow shapes, so the laser path is responsible for poor control of surface roughness.In addition, PBF processes are not suitable for multi-material 3D printing, being this the next challenge for AM technologies. [7] For instance, powders delivery systems need to be redesigned to grant for proper multi-material combination.Another class of emerging technologies to 3D print metallic components are those classified as extrusion-based, where a metallic-based filament or paste is extruded through a nozzle at mild or room temperature. In both cases, gas-atomized metallic powders are mixed with a polymeric binder to obtain an extrudable filament or paste. In the first case, the technology is called fused deposition modeling (FDM, used for rapid prototyping) or fused filament fabrication (FFF), while in the second case it is called direct ink writing (DIW).FFF and DIW show the advantage of printing at mild or room temperature and the versatility to use more filaments or pastes, for instance, to 3D print multi-material components; the printed part must undergo a de-binding and sintering treatment to remove the polymeric binder and to densify the metallic powders into the final part. The preparation of a homogeneous and printable filament or paste remains one of the key points of these techniques, so de-binding and sintering must grant for the absence of organic binder residues. Sintering at high

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Effect of atomization on surface oxide composition in 316L stainless steel powders for additive manufacturing

Cited by 35 publications

References 37 publications

Pitting Corrosion in 316L Stainless Steel Fabricated by Laser Powder Bed Fusion Additive Manufacturing: A Review and Perspective

Pitting Corrosion in 316L Stainless Steel Fabricated by Laser Powder Bed Fusion Additive Manufacturing: A Review and Perspective

Non-oxide precipitates in additively manufactured austenitic stainless steel

Direct Ink Writing of AISI 316L Dense Parts and Porous Lattices

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