Fabrication and characterization of a functionally graded material from Ti-6Al-4V to SS316 by laser metal deposition

In this study, laser metal deposition (LMD) was employed to explore a new fabrication process for producing a functionally graded material (FGM) from Ti-6Al-4V to SS316. A transition composition route was introduced (Ti-6Al-4V→V→Cr→Fe→SS316) to avoid the intermetallic phases between Ti-6Al-4V and SS316. A thin wall sample was fabricated via LMD by following the transition composition route. Microstructure characterization and composition distribution analyses were performed by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The SEM images depicted the microstructural morphology of the FGM sample. The element gradient distribution determined by the EDS results may reflect the FGM transition composition route design. X-ray diffraction tests were conducted and the results demonstrated that the generation of intermetallic phases effectively avoided following the composition route. The Vickers hardness test was used to determine the Vickers hardness number (VHN) distribution from Ti-6Al-4V to SS316. The VHN results showed that no significant formation of hard brittle phases occurred in the LMD procedure.