Elaboration of oxide dispersion strengthened Fe-14Cr stainless steel by selective laser melting

Abstract

et al.. Elaboration of oxide dispersion strengthened Fe-14Cr stainless steel by selective laser melting. Abstract: This study presents the influence of the main selective laser melting (SLM) processing parameters on the densification behavior and microstructure evolution of oxide dispersion strengthened (ODS) Fe-14Cr stainless steel. Optimization of the process parameters allows to manufacture ODS stainless steel parts, which present high densities up to 98% and a fine dispersion of nanosized Y-Ti rich oxide particles. Laser power and scan speed are found to strongly influence the density and the microstructure of SLM builds. The ratio power over scan speed controls the width and the depth of the molten pool. Low energy densities (i.e. a low laser power or a high scan speed), inferior to 100 J.mm -3 , cause lack of fusion of the powder and induce the presence of numerous pores. Finer microstructure can be achieved in this condition since grains receive less energy to growth. The hatch distance does not affect the density in the range of testing values. A decrease in hatch distance causes re-fusion of previous neighbor track but does not re-melt the previous layer since the ratio power over speed is kept constant when varying the hatch distance. A slight coarsening of the microstructure is observed in this case. A large range of hatch distance can be used and especially large values, which decrease the time of production. This study can be a guideline to achieve materials with specific microstructure for high temperature applications. [19] References: A. R. Jones, 2010. Historical perspective: ODS alloy development. AlMangour, B., Grzesiak, D., Borkar, T., Yang, J.-M., 2018. Densification behavior, microstructural evolution, and mechanical properties of TiC/316L stainless steel nanocomposites fabricated by selective laser melting. Materials & Design 138, 119-128. https://doi.-M., 2017. Scanning strategies for texture and anisotropy tailoring during selective laser melting of TiC/316L stainless steel nanocomposites. Journal of Alloys and Compounds 728, 424-435. https://doi., J., 2014. Selective laser melting of in situ titanium-titanium boride composites: Processing, microstructure and mechanical properties. Acta Materialia 76, 13-22. https://doi.org/10.1016/j.actamat.2014.05.022 Attar, H., Ehtemam-Haghighi, S., Kent, D., Dargusch, M.S., 2018. Recent developments and opportunities in additive manufacturing of titanium-based matrix composites: A review. International Journal of Machine Tools and Manufacture 133, 85-102. https://doi.

Oxide dispersion strengthened stainless steel 316L with superior strength and ductility by selective laser melting

“…[18] Vasquez et al achieved 98% of density and the fine dispersion of nanosized Y-Ti-O particles by using a powder mixture (steel, Y2O3 and TiH2 ) prepared by ball milling for extended duration of 176 hours. [19] Boegelein et al fabricated ferritic ODS-PM2000 samples by SLM from a pre-alloyed powder, in which non-randomly occurred voids, up to 150 µm in size, and inclusions up to 50 µm in size were observed. Smaller pores (≤ 20 µm in size) and finely distributed nanoinclusions with a mean size of 17 nm formed inside the thin walls.…”

Laser Powder Bed Fusion of ODS 14YWT from Gas Atomization Reaction Synthesis Precursor Powders

“…Many studies using laser powder bed fusion (LPBF) AM have utilized ferritic or austenitic steels mechanically alloyed with Y 2 O 3 as AM feedstock. [10][11][12][13][14][15][16][17][18][19][20] Alternatively, low-energy ball milling and blending, [21][22][23] along with methods to deposit oxides onto powders in situ, have been reported as alternative feedstock techniques for fabrication by AM. [24][25][26][27][28] While some promising results have been reported, challenges related to heterogeneity and agglomeration of pre-existing Y 2 O 3 remain, and these approaches typically depend on MA processing, which can be a limiting factor to scalability.…”

“…The objective of the present study was first to develop LPBF AM process maps for predicting build results ranging from porous structures to unstable/ swelled structures for 14YWT GARS precursor powders to identify parameters that yield high density and process stability/repeatability. In the reported literature on the LPBF of ODS steels, only a few discuss the processing parameters used 20,39,43 and, of those, it is not universally clear whether the reported oxide sizes and densities can be associated with a stable processing space. The second objective was to identify the distribution of elements and phases within the GARS powder and lastly to downselect to the stable samples with the highest density and to characterize the microstructure, material properties, and distribution of nano-scale oxides in the LPBF produced ODS steel matrix.…”

Nanoparticle Tracing during Laser Powder Bed Fusion of Oxide Dispersion Strengthened Steels

“…However, recent studies on this topic show that it is difficult to achieve the optimum nanoparticle size according to the Orowan mechanism due to segregation or agglomeration of the nanoparticles, which in turn was found to deteriorate the mechanical properties of the part [13]. Approaches to optimize the process such as evaluating the influence of the powder characteristics [14] and process parameters [15], or alternative additivation routes such as light mixing [16], improve the dispersion of the nanoparticles; however, they still lack control over the nanoparticle size.…”