Evolution of 316L stainless steel feedstock due to laser powder bed fusion process

Heiden, Michael; Deibler, Lisa Anne; Rodelas, Jeffrey; Koepke, Josh R.; Tung, Dan J.; Saiz, David J.; Jared, Bradley Howell

doi:10.1016/j.addma.2018.10.019

Cited by 88 publications

(134 citation statements)

References 58 publications

Supporting

Mentioning

117

Contrasting

Unclassified

Order By: Relevance

“…What is most striking from the results performed on many different alloys (stainless steels, Ti-6Al-4V, Alsi10Mg, IN718 and IN625, Co-Cr, Scalmalloy) [19,30,37,58,[82][83][84][85][86][87][88], in terms of reused powder characterization and, most importantly, of the microstructural and mechanical properties of the final parts, is that, while the former are quite similar for the same alloy, the latter are characterized by very scattered results [23]. Mechanical properties could be improved, decreased, or unaffected by the reuse of feedstock material, as shown by the results reported in Table 1.…”

Section: Powder Feedstock Featuresmentioning

confidence: 99%

“…These results suggest that the reuse of powders with condensate content should be prevented, but more studies specifically focused on this topic are needed in order to monitor the condensate formation and evolution for different alloys. [37] with permission from Elsevier.…”

Section: Condensatementioning

confidence: 99%

“…The interaction between the high-energy laser typical of LPBF equipment and the metal powder bed can result in powder contamination through different phenomena including agglomeration, partial fusing, partial/full oxidation, metal vapor condensate, and generation of spatter [32][33][34][35][36][37][38][39][40]. These phenomena can alter not only the properties of the reused powder (i.e., flowability, chemical composition, tap density, particle size), but also the surface (i.e., roughness), microstructural (i.e., local variation of chemical composition, pore formation), and mechanical properties of the final part.…”

Section: Introductionmentioning

confidence: 99%

“…As mentioned above, when the time of flight is long enough, the surface of the spatter particles can experience strong oxidation, mostly in the case of highly reactive powders (i.e., Ti-6Al-4V) and powders with chemical composition characterized by the high presence of elements with a high oxidation potential (i.e., stainless steels). As a matter of fact, the presence of oxygen and interstitial elements in general (i.e., H, O) on the particles or within the environment of the build chamber (insufficient inert gas flow) can impact the chemical composition of the melt pool and its surface tension, causing unfavorable wetting conditions and affecting the following solidification and densification of the metal part [37,135]. Therefore, depending on the application of the part to be produced (biomedical, aeronautical, structural, or just a prototype), a different level of accuracy concerning the removal of heat-affected particles should be used.…”

mentioning

confidence: 99%

“…It is also worth noting that, in the case of 316L stainless steel, the interaction of the powder particles with the laser radiation can give rise to ejections with a different phase composition (higher amount of δ ferrite) and to spatter with a high ferrite content (Fe3O4, iron oxide), which could also affect their magnetic behavior and, therefore, their flowability [37,126] (Figure 9). Energy-dispersive spectroscopy was also used to identify oxide island patches on the surface of these particles as silicon oxide [101].…”

mentioning

confidence: 99%

See 4 more Smart Citations

Material Reuse in Laser Powder Bed Fusion: Side Effects of the Laser—Metal Powder Interaction

Santecchia

Spigarelli

Cabibbo

2020

Metals

View full text Add to dashboard Cite

Metal additive manufacturing is changing the way in which engineers and designers model the production of three-dimensional (3D) objects, with rapid growth seen in recent years. Laser powder bed fusion (LPBF) is the most used metal additive manufacturing technique, and it is based on the efficient interaction between a high-energy laser and a metal powder feedstock. To make LPBF more cost-efficient and environmentally friendly, it is of paramount importance to recycle (reuse) the unfused powder from a build job. However, since the laser-powder interaction involves complex physics phenomena and generates by-products which might affect the integrity of the feedstock and the final build part, a better understanding of the overall process should be attained. The present review paper is focused on the clarification of the interaction between laser and metal powder, with a strong focus on its side effects. Figure 1. Schematics of the laser powder bed fusion (LPBF) equipment. Adapted from Reference [9] with permission from Elsevier.While the market and the applications of laser powder bed fusion continuously and impressively grew in recent years, there is a common view across users and researchers concerning the repeatability of the process in terms of chemical composition and mechanical properties of the final parts, which are of paramount importance when challenging environmental or testing conditions are considered [10][11][12][13][14][15][16].The most typical approach to study the microstructural and mechanical properties of parts built by LPBF is to compare them with castings of the same alloy or, rather, the corresponding alloy since the starting material is metal powder rather than a fuse. However, in some existing alloys designed for cast and wrought parts, laser additive manufacturing processing results in cracking or other microstructure deficiencies [11,12,16,17]. It is worth noting that LPBF has more similarities with laser welding rather than casting, since the two laser-based techniques have some common features (i.e., melt-pool formation, moving heat source) [18]. However, process parameters are, in general, quite different in terms of laser power and scan speed, and the laser-matter interaction is much more complicated in LPBF processes, since the powder feedstock is inherently unstable and the solidified material undergoes multiple thermal cycles corresponding to the fusion of subsequent layers during the additive process [19][20][21][22]. Furthermore, owing to the similarities with welding and to the complicated interaction between laser and metal particles, when comparing laser powder bed fusion with other metal forming processes, it is evident that the range of processable alloys is very limited and the number of high-productivity commercially available alloys is even smaller [23]. One of the reasons behind this is that the level of metal powder sensitivity to the laser action during LPBF is not yet fully understood, despite the efforts of the scientific community to uncover it [24][25][26][27], and ...

show abstract