Search

The interactions between microstructure evolution and mechanical properties of square-celled TRIP steel and particle-reinforced TRIP steel/zirconia honeycombs are investigated over a wide range of test temperatures. Based on a powder metallurgical route of a ceramic extrusion technology, two-dimensional channeled structures are made of an austenitic AISI 304 CrNi-steel or a TRIP steel matrix composite with up to 10 vol.% of a MgO partially stabilized zirconia (Mg-PSZ) ceramic. Honeycomb specimens with a cell frame of 196 cpsi and a relative density of 0.37 (viz. 2.9 g cm−3) are tested under quasi-static compression in out-of-plane loading direction at temperatures between -196 °C and 150 °C. During compression, the cellular materials deform in a strain-dominated buckling mode initiating a plastic hinge formation in the cell walls at higher strain levels. Their crush resistance is intensively controlled by the material design including the plastic yield and strengthening mechanisms of the TRIP steel matrix and the constraint or particle reinforcement effects of the embedded zirconia ceramic. Since the thermodynamic driving force for the α′-martensite nucleation and the intrinsic stacking fault energy are strongly influenced by temperature, different material strengthening and softening processes and a varied microstructure evolution are detected. A sigmoidal initial stress-strain response as well as the highest compression stress are measured at test temperatures below room temperature due to a pronounced α′-martensite volume fraction. However, at higher test temperatures, mechanical twinning and dislocation glide are the dominant deformation mechanisms. In summary, strength, ductility and energy absorption which identify the crashworthiness of the honeycombs, are significantly affected by the temperature-sensitive macro- and microstructure phenomena. [ABSTRACT FROM AUTHOR]