Influence of interface on microstructure and mechanical properties of laser-direct energy deposited Ti60 alloy

In this study, the laser-direct energy deposition (L-DED) was employed to fabricate Ti60 structures on the wrought Ti60 substrate. Detailed microstructure characterization and mechanical behavior investigation of the deposited material and substrate material were carried out. The parameter of the improved indentation inversion algorithm was optimized to obtain local elastoplastic properties of the interface between deposition and substrate. Quantitative analyses show that the interface exhibits improved mechanical properties compared to the wrought substrate. The theoretical strengthening models confirms that by introducing overall alpha texture and acicular alpha/alpha ' in deposited zone and heat-affected zone, additional grain boundary strengthening is achieved by reducing the effective grain size, while simultaneously achieving additional dislocation strengthening when compared to the substrate zone. For the sample which has both deposited material and substrate, the yield and fracture stresses are determined by the strength of the wrought substrate. The over-matching between the deposited zone with higher strength and the substrate zone does not compromise the overall structural strength.