Manas Vijay Upadhyay1, Meriem Ben Haj Slama2,3, Steve Gaudez2,4, Nikhil Mohanan2, Lluis Yedra3,5,6, Simon Hallais2, Eva Héripré3, Alexandre Tanguy2. 1. Laboratoire de Mécanique des Solides (LMS), CNRS UMR 7649, Ecole Polytechnique, Institut Polytechnique de Paris, 91128, Palaiseau, France. manas.upadhyay@polytechnique.edu. 2. Laboratoire de Mécanique des Solides (LMS), CNRS UMR 7649, Ecole Polytechnique, Institut Polytechnique de Paris, 91128, Palaiseau, France. 3. Laboratoire de Mécanique des Sols, Structures et Matériaux (MSSMat), CNRS UMR 8579, CentraleSupélec, Université Paris-Saclay, 91190, Gif-sur-Yvette, France. 4. Institut Jean Lamour (IJL), CNRS UMR 7198, Université de Lorraine, Campus ARTEM, Nancy, France. 5. Laboratoire Structures, Propriétés et Modélisation des Solides (SPMS), CNRS UMR 8580, CentraleSupélec, Université Paris Saclay, 91190, Gif-sur-Yvette, France. 6. Department of Electronics and Biomedical Engineering, Institute of Nanoscience and Nanotechnology (IN2UB), University of Barcelona, 08028, Barcelona, Catalonia, Spain.
Abstract
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.
Precipitates in an austenitic pan class="Chemical">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.