Please cite this article in press as: G. Marchese, et al., Met. Powder Rep. (2016), http://dx.doi.org/10.1016/j.mprp.2016.06.002 Metal Powder Report  Volume 00, Number 00  June 2016 metal-powder.net Microstructural investigation of as-fabricated and heat- treated Inconel 625 and Inconel 718 fabricated by direct metal laser sintering: contribution of Politecnico di Torino and Istituto Italiano di Tecnologia (IIT) di Torino Giulio Marchese 1 , Emilio Bassini 1 , Michele Calandri 1 , Elisa Paola Ambrosio 2 , Flaviana Calignano 2 , Massimo Lorusso 2 , Diego Manfredi 2 , Matteo Pavese 1 , Sara Biamino 1 and Paolo Fino 1,2 1 Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, Torino 10129, Italy 2 Center for Sustainable Futures CSF@Polito, Istituto Italiano di Tecnologia, Corso Trento 21, Torino 10129, Italy The Ni-based superalloys are widely used in aerospace and aeronautic industries, but building complex shape components with conventional technologies is expensive. Nowadays, it is possible to use techniques such as direct metal laser sintering (DMLS) process to overcome this problem. In the present report are summarized the activities performed at the Department of Applied Science and Technology (DISAT) of Politecnico di Torino and Istituto Italiano di Tecnologia (IIT) di Torino on the development of Ni-based superalloys produced by DMLS. More precisely, we have studied the microstructure architectures of Inconel 625 and Inconel 718 produced by M270 Dual Mode version and the impact of different heat treatments on their microstructures in order to meet the industrial requirements. Additive manufacturing Additive manufacturing (AM) represents a family of process that can fabricate components through layer by layer process, using a 3D computer aided design (CAD) data. These technologies allow the production of near net shape components, also with a very complex shape, without requesting long subtraction processing. Regarding the production of superalloys, the laser and electron beam melting are the most attractive AM technologies available. Laser technologies can be differentiated according to the deposi- tion mode of powdery material, being direct laser deposition (DLD) and powder bed fusion-laser (PBF-L) the most important processes. In these cases, we have several producers of laser beam technologies. In the first family of manufacturing routes, one can include laser metal deposition (LMD) in which a high-energy laser beam is directed on a substrate to form a melt pool and at the same time powders or wires are delivered in the melt pool. Generally, in these machines the substrate is moved according to the shape of the components whilst the laser and feeding system is fixed. Instead, in the second family of processes, one can include direct metal laser sintering (DMLS), trade name of EOS for the selective laser melting (SLM) process, in which a laser selectively melt some areas of a layer of loose powder deposited on a substrate inside a chamber filled with inert gas. Finally, only one company (ARCAM) produces machines that use electron beam under high vacuum to melt the powder with the name of electron beam melting (EBM) [1–3]. This paper summarizes the main results on the study of Ni- based superalloys produced by DMLS, developed at Department of Applied Science and Technology (DISAT) of Politecnico di Torino and Istituto Italiano di Tecnologia (IIT), in the Center for Sustain- able Futures also settled in Torino. In particular, we have studied two Inconel alloys, Inconel 625 and 718, investigating their microstructures and the effects of heat treatments on the micro- structure. The process parameters for these two alloys have been defined and components as well as prototypes production is currently available at our site. Inconel 625 and Inconel 718 produced by DMLS Inconel 718 and 625 have been used in high-temperature applica- tions, such as gas-turbine engines aircraft, nuclear reactors, pumps and molds. These alloys are endowed with high-temperature SPECIAL FEATURE E-mail address: giulio.marchese@polito.it. 0026-0657/ß 2016 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.mprp.2016.06.002 1