Mechanical and microstructural properties of Ti–6Al–4V hybrid parts produced by LPBF: effect of deposited geometry and laser power

Hybrid Additive Manufacturing combines the high productivity of forming processes with the design freedom and customization of additive manufacturing. This study investigates the mechanical performance of hybrid components consisting of L-PBF features deposited on Ti-6Al-4V sheets under different process conditions. Because the integrity of the bonding interface is critical for the structural reliability of hybrid parts, the bonding strength was evaluated by means of three-point bending tests, macrostructural and microstructural analyses, and microhardness measurements. The distortions of the geometries along the building direction were also quantified and used to validate a numerical model of the L-PBF process on the metal sheet. The analysis revealed significant interactions among the process parameters, as identified through ANOVA. These interactions enabled the definition of two characterization parameters for the additive parts that are independent of the specific geometry considered. One is an index to quantify the symmetry of the deposited surface (IoS), and the other is to evaluate the heat accumulation (HAV). The results demonstrate that the interface area and the symmetry of the additive part are the dominant factors controlling the mechanical strength of the hybrid component, through their effect on the residual stress distribution after processing. Based on these findings, a second-degree polynomial model was developed as a practical decision-making tool for selecting geometric and process parameters that ensure the required bonding strength in hybrid parts.