Effect of argon and nitrogen atmospheres on the properties of stainless steel 316 L parts produced by laser-powder bed fusion

Pauzon, Camille Nicole Géraldine; Hryha, Eduard; Forêt, Pierre; Nyborg, Lars

doi:10.1016/j.matdes.2019.107873

Cited by 85 publications

(55 citation statements)

References 18 publications

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“…While all the nitrogen initially present in the feedstock powder seems to be transferred to the built material, significant oxygen loss of up to about 200 ppm was registered. A similar result was already reported [5] and attributed to the removal of the surface bound oxygen, present on powder feedstock due to the high surface area, and oxygen removal by transfer to projections. Regardless of the process atmosphere, the 1 mm samples picked up more oxygen than the 3 mm samples, see Table I.…”

Section: Resultssupporting

confidence: 88%

“…As previously shown, this system allows to achieve oxygen levels of about 2000 ppm O 2 compared to technical gas, which usually results in less than 800 ppm O 2 . [5] The slightly higher oxygen contents measured for the helium specimens could be related to the non-optimal oxygen calibration and sensors of the L-PBF machine for helium. Soon after starting the process, the sensor displayed 0 pct O 2 .…”

Section: Resultsmentioning

confidence: 98%

“…Argon 5.0 and Helium 4.6 feature less than 10 and 40 ppm impurities, respectively. In light of previously published evidence of the limited effect of residual oxygen on 316L stainless steel properties built by L-PBF, [5] the internal generator was used to produce a nitrogen rich atmosphere (about 2000 ppm residual O 2 ) by filtering compressed air. Although the considered gases have different densities and thermal properties, the differential pressure of the machine was adjusted to achieve the same gas speed over the powder bed of about 2.2 m/s.…”

Section: Methodsmentioning

confidence: 99%

“…[3] In addition to affecting the chemistry of the produced parts, the degradation and recyclability of the powder particles can be compromised. [4] Our previous work [5] demonstrated that atmosphere purity of 1000 ppm O 2 and below allows high mechanical performances for 316L stainless steel, exceeding the one for wrought material. It was also highlighted that the atmosphere purity can be critical for the surface oxidation state of 316L powder upon oxygen levels of 2000 ppm and above.…”

Section: Introductionmentioning

confidence: 99%

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Effect of the Process Gas and Scan Speed on the Properties and Productivity of Thin 316L Structures Produced by Laser-Powder Bed Fusion

Pauzon

Leicht

Klement

et al. 2020

Metall Mater Trans A

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The development of the laser powder bed fusion (L-PBF) process to increase its robustness and productivity is challenged by ambitious design optimizations, such as thin wall structures. In this study, in addition to the effect of commonly used gases as Ar and N2, increased laser scanning speed and new process gases, such as helium, were successfully implemented. This implementation allowed to build 316L stainless steel components with thin walls of 1 mm thickness with an enhanced build rate of 37 pct. The sample size effect and the surface roughness were held responsible for the reduction in strength (YS > 430 MPa) and elongation (EAB > 30 pct) for the 1 mm samples studied. Similar strength was achieved for all process gases. The increased scanning speed was accompanied by a more random texture, smaller cell size, and grain size factor along the building direction when compared to the material built with the standard laser parameters. Stronger preferential orientation 〈101〉 along the building direction was observed for material built with standard parameters. Finally, the use of helium as a process gas was successful and resulted in reduced cell size. This finding is promising for the future development of high strength 316L stainless steel built with high build rates.

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Section: Resultssupporting

confidence: 88%

Section: Resultsmentioning

confidence: 98%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effect of the Process Gas and Scan Speed on the Properties and Productivity of Thin 316L Structures Produced by Laser-Powder Bed Fusion

Pauzon

Leicht

Klement

et al. 2020

Metall Mater Trans A

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“…However, the presence of such phase on a 316L powder surface in similar amounts was found not to be detrimental in the case of L‐PBF, as such particulates were found as fine inclusions with a similar or identical composition inside the dimples on the fracture surface, with no registered impact on mechanical properties due to their low content in the material 40 . Similarly, no nitrogen‐rich inclusions were found within the dimples of the same study, hence the nitrogen remains in solid solution throughout L‐PBF processing 40 . Furthermore, in SiO 2 ‐Cr 2 O 3 systems, such low melting phases do not form, and thus, the oxidation products found on the WA sample would not pose a risk.…”

Section: Discussionmentioning

confidence: 90%

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

Riabov

Hryha

Rashidi

et al. 2020

Surface & Interface Analysis

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The initial oxide state of powder is essential to the robust additive manufacturing of metal components using powder bed fusion processes. However, the variation of the powder surface oxide composition as a function of the atomizing medium is not clear. This work summarizes a detailed surface characterization of three 316L powders, produced using water atomization (WA), vacuum melting inert gas atomization (VIGA), and nitrogen atomization (GA). X‐ray photoelectron spectroscopy (XPS) and scanning electron microscopy analyses were combined to characterize the surface state of the powders. The results showed that the surface oxides consisted of a thin (~4 nm) iron oxide (Fe2O3) layer with particulate oxide phases rich in Cr, Mn, and Si, with a varying composition. XPS analysis combined with depth‐profiling showed that the VIGA powder had the lowest surface coverage of particulate compounds, followed by the GA powder, whereas the WA powder had the largest fraction of particulate surface oxides. The composition of the oxides was evaluated based on the XPS analysis of the oxide standards. Effects of Ar sputtering on the peak positions of the oxide standards were evaluated with the aim of providing an accurate analysis of the oxide characteristics at different etch depths.

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Einfluss der Abkühlrate auf die mechanischen Eigenschaften von additiv gefertigten Zugproben aus 316L

et al. 2020

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Das pulverbettbasierte Laserstrahlschmelzen (LPBF) erfreut sich aufgrund des hohen Grads an Flexibilität und seiner Möglichkeit, strukturoptimierte Komponenten herzustellen, großer Beliebtheit. Im Prozess wird zunächst ein 3D-CAD-Modell in Schichten von 20 µm bis 100 µm aufgeteilt. Für den schichtweisen Aufbau des Bauteils trägt die Maschine eine gleichmäßige Pulverschicht mit definierter Schichtdicke auf eine materialverwandte Bauplattform auf. Anschließend belichtet der Laser die zu verfestigenden Regionen der aktuellen Schicht. Dem folgt ein erneuter Pulverauftrag. Dieser Vorgang wird so lange fortgeführt, bis das Bauteil vollends aufgebaut ist (schematisch in Bild 1) [1]. Stichworte additive Fertigung; pulverbettbasiertes Laserstrahlschmelzen (LPBF); Abkühlrate; 316L (1.4404) Effect of cooling rate on the mechanical properties of 316L tensile specimen, manufactured by Laser Powder Bed Fusion Laser-Powder Bed Fusion (LPBF) is an additive manufacturing process, which allows weight savings of components through structural optimization without loss of stiffness. The mechanical properties are comparable with casted and-under ideal conditions-even with forged components. In the aerospace industry, as well as in the automotive and medical sector, LPBF is already applied. However, LPBF has only been used for components which are not safety-related. This is mainly due to the unreliable reproducibility of the mechanical properties of this process. Research has to be executed to find correlations bet ween LPBF-parameters and reliable product properties. This report investigates the relationship between cooling rates in the LPBF process and the resulting mechanical properties of 316L (1.4404). For this purpose, different sample geometries were manufactured. The respective cooling rates were measured by in-situ-thermography. After that, tensile tests and metallurgical investigations were performed. Depending on the geometry, different cooling rates were observed, which finally led to different tensile strength results. Keywords additive manufacturing; Laser Powder-Bed Fusion (LPBF); cooling rate; 316L (1.4404) Bild 1 Grundsätzliches Funktionsprinzip des pulverbettbasierten Laserstrahlschmelzens Basic principle of laser-powder bed fusion

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Effect of argon and nitrogen atmospheres on the properties of stainless steel 316 L parts produced by laser-powder bed fusion

Cited by 85 publications

References 18 publications

Effect of the Process Gas and Scan Speed on the Properties and Productivity of Thin 316L Structures Produced by Laser-Powder Bed Fusion

Effect of the Process Gas and Scan Speed on the Properties and Productivity of Thin 316L Structures Produced by Laser-Powder Bed Fusion

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

Einfluss der Abkühlrate auf die mechanischen Eigenschaften von additiv gefertigten Zugproben aus 316L

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Effect of argon and nitrogen atmospheres on the properties of stainless steel 316 L parts produced by laser-powder bed fusion

Cited by 85 publications

References 18 publications

Effect of the Process Gas and Scan Speed on the Properties and Productivity of Thin 316L Structures Produced by Laser-Powder Bed Fusion

Effect of the Process Gas and Scan Speed on the Properties and Productivity of Thin 316L Structures Produced by Laser-Powder Bed Fusion

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

Einfluss der Abkühlrate auf die mechanischen Eigenschaften von additiv gefertigten Zugproben aus 316L

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Effect of argon and nitrogen atmospheres on the properties of stainless steel 316 L parts produced by laser-powder bed fusion