Wire and arc additive manufacturing of 316L stainless steel/Inconel 625 functionally graded material

In this work, a 316L stainless steel to Inconel 625 functionally graded material (FGM) was built using different deposition strategies (named as direct and smooth-type interfaces) by Twin-Wire and Arc Additive Manufacturing (T-WAAM). This combination of materials is of interest in chemical plants, oil & gas, and nuclear applications, where high corrosion and wear resistance are essential requirements. Although these properties are superior in Inconel 625, replacing Inconel with stainless steel in strategic regions of structural components can reduce the overall costs and parts' weight. Both direct and smooth transition interfaces were tested and characterized. Microscopic analysis revealed that each interface and the as-built samples had an austenitic matrix, and every sample was well bonded and free of defects. Different types of microstructures evolved at the interfaces due to distinct gradients in composition. Synchrotron X-ray diffraction measurements showed that the smooth-gradient produced secondary phases, such as δ-phase (Ni3Nb) and carbides, that were not present with the direct interface strategy. Overall, the properties were superior in the FGM with a direct interface, which experienced higher strengths and elongations upon failure. Moreover, neutron diffraction measurements revealed that lower residual stresses developed in the direct interface FGM than in the smooth gradient FGM.

Descrição

Funding Information: TAR, AM, FF, TGS, and JPO acknowledge Fundação para a Ciência e a Tecnologia (FCT–MCTES) for its financial support via the project UID/00667/2020 (UNIDEMI). JPO acknowledges the funding of CENIMAT/i3N by national funds through the FCT-Fundação para a Ciência e a Tecnologia, IP, within the scope of Multiannual Financing of R&D Units, reference UIDB/50025/2020-2023. JS acknowledges the China Scholarship Council for funding the Ph.D. grant (CSC NO. 201808320394 ). This activity has received funding from the European Institute of Innovation and Technology (EIT) – Project Smart WAAM: Microstructural Engineering and Integrated Non-Destructive Testing. This body of the European Union receives support from the European Union's Horizon 2020 research and innovation program. The authors acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for providing experimental facilities. Beamtime was allocated for proposal I-20210899 EC. Publisher Copyright: © 2022 The Author(s).

Palavras-chave

Functionally graded material (FGM) Inconel 625 Stainless steel 316 Wire and arc additive manufacturing (WAAM) Ceramics and Composites Biomaterials Surfaces, Coatings and Films Metals and Alloys