Multiscale ductile fracture integrating tomographic characterization and 3-D simulation

Ductile fracture in alloys is a multiscale process in which primary voids formed at micron-scale particles coalesce by a zig-zag pattern of shear localization driven by finer-scale microvoiding at submicron-scale secondary particles. Employing the method of serial sectioning, unprecedented 3-D microstructural reconstructions of steel crack-tip process zones are obtained and implemented into a large-scale simulation for ductile fracture analysis. A quantitative understanding of the microvoid sheeting mechanism and mixed-mode failure controlling the zig-zag fracture surface are presented using the modeling technique utilized herein. We define and quantify metrics of fracture by analyzing the crack opening distance, process zone size, zig-zag wavelength and void growth ratios in the crack tip reconstructions. The quantitative agreement of these metrics between experiment and simulation supports a new and developing predictive structure/property theory to enable materials design.