Microstructure in work-hardened micro-truss materials given post-forming annealing treatments

Paper in proceeding, 2010

Micro-truss cellular materials can be used as structurally efficient cores in light-weight sandwich panels. These sandwich cores have been produced using deformation-forming approaches, which introduce plastic strain into the truss struts. While this imparted strain can be used to strengthen the overall micro-truss core, it also drives recrystallization and grain growth if sandwich panel assembly involves conventional brazing treatments that subject the truss core to elevated temperatures. In addition to losing a potential strengthening mechanism, brazing can also result in the grain size of the annealed microstructure approaching the cross-sectional dimensions of the micro-truss struts. The present study is an examination of the strut microstructures in aluminum alloy and stainless steel micro-truss materials fabricated using a deformation-forming approach, and following a post-fabrication annealing step. These results serve as a guideline for future sandwich panel thermal processing to minimize the reduction of strength due to annealing and detrimental size effects.