Fabrication of lattice truss structures by novel super-plastic forming and diffusion bonding process in a titanium alloy

A novel superplastic forming/diffusion bonding method has been developed to produce lattice truss structure from Ti6Al4V titanium alloy. A three-layer lattice sandwich structure was fabricated. The compression and shear processes of as-made structures were simulated by finite element method and measured by tests. The results showed that the relationship between shear stress and strain for the present structure was different from that of structures made through traditional brazing or welding process. Several stress fluctuations occurred in the compressive stress-strain curve and there was no conventional yield platform in shear stress-strain curve. The compressive finite element simulation pattern was consistent with test result, while there was relatively large deviation between the shear simulation and test results. The face sheet-core interface had adequate bond strength and no node failure was observed in both tests. The node robustness was mainly attributed to the homogeneity of the fine microstructure at node positions. (C) 2015 Elsevier Ltd. All rights reserved.