Figure 4
Comparison of mechanical properties of the hierarchical steel with those of other steels. (a) Hardness distribution along the cross-section of an as-annealed steel, as compared to our hierarchical steel. Results indicate that the hierarchical steel (red scattering) attains larger improvements in hardness as compared to as-annealed steels. (b) Uniaxial tensile tests show engineering stress–strain curves of the hierarchical steel (in red triangle scattering), as compared with that of as-annealed steel; inset graphs show the corresponding true stress-strain curves. Representative tensile properties of steels are shown in (c) and (d). The data are for dual-phase steels, TRIP-steels, classical gradient steels and our hierarchical steel (this work). Red triangle data points represent the tensile properties of the hierarchical steel. A comparison of the respective yield (c) and ultimate tensile strengths (d) of dual-phase steels, TRIP-steels, classical gradient steels and hierarchical steels, indicates that the hierarchical steels have a far superior combination of strength and ductility in comparison to other steels.
