Inconel-steel functionally bimetal materials by hybrid directed energy deposition and thermal milling: Microstructure and mechanical properties

Many engineering applications, particularly those in extreme environments, require components with properties that vary with location in the part. Functionally bimetal materials (FBM) that combine dissimilar materials, such as those with different density and thermal properties, provide a potential solution to this need. Directed energy deposition (DED) is convenient to fabricate all kinds of complicated parts and to clad different materials at specific locations. Milling can improve the surface quality and dimensional accuracy after DED. Hybrid DED and thermal milling manufacturing can fabricate FBMs and be applied to laser repair. This study used this new method to fabricate Inconel-steel FBM. Inconel 718 powder and 316L stainless steel powder were deposited on the thermal milling surface of parts prepared with DED. The interfacial characteristics of different cladding materials were compared. Microstructure, chemistry, phase composition, element segregation and microhardness varied with position and were characterized by energy dispersive spectroscopy, Xray diffraction, scanning electron microscopy and microhardness testing. Finally, the tensile properties of the FBM were compared to other materials, and the fracture location and morphology were analyzed. The results showed that the yield strength (YS) reached 368 MPa, and the ultimate tensile strength (UTS) reached 516 MPa. The Vickers microhardness of the diffusion layer was approximately 250 HV. (C) 2019 Politechnika Wroclawska. Published by Elsevier B.V. All rights reserved.