Development and characterization of Ti-6Al-4V to 304L stainless steel gradient components fabricated with laser deposition additive manufacturing

In this study, a multi-hopper laser deposition system is used to additively manufacture functionally graded Ti-6Al-4V to 304L stainless steel components with a vanadium interlayer. Grain morphology, phase, and composition are mapped along the component gradients with electron backscatter diffraction (EBSD) and energy dispersive X-ray spectroscopy (EDS), and mechanical property changes are assessed utilizing Vickers hardness and nanoindentation. Precipitation of brittle intermetallic compounds such as FeTi and the formation of an Fe-V-Cr sigma phase are confirmed to be the causes ofmid-fabrication cracking in the components. Guided by multicomponent phase diagrams, alternate paths in composition space are proposed to strategically avoid unfavorable phase formation along the gradient. Composition-dependent adjustment of process parameters is also proposed to reduce the prevalence of observed powder inclusions, homogenize grain morphology, and improve component mechanical properties. (C) 2016 Elsevier Ltd. All rights reserved.