Fractal-nature of tessellated hierarchical 3D nano-layered dimples

Culmination of any continuous deformation process is nothing but fracture. Hence, it is possible that the fracture surface would keep the imprint of entire deformation process operated. Experimental quantification of dimple geometry and its fractal dimension (D_f) from published fractographs of a maraging steel with different austenite (fcc) fractions have been assessed/correlated with tensile responses. Elongation (e) is found to be directly proportional to dimple size (D_IL) and D_f while strength properties (yield strength-σ_ys, tensile strength-σ_uts, hardness-HV) are inversely proportional to D_IL and D_f. The fracture geometry/patterns on tensile fractographs logically reflect the multiplicity of micro-void nucleating sites at different microstructural conditions due to heat-treatments (H/Ts).