An overview of tailoring strain delocalization for strength-ductility synergy
Hao Wu, Guohua Fan
Abstract
In this paper, we systematically proposed the strategy of tailoring strain delocalization to evade long-standing strength-ductility trade-off dilemma. The scientific contribution is to define and, for the first time, to expand the category of strain localization into the whole deformation process, including elastic lattice distortion, plasticity-relevant statistical behaviors (dislocation, twinning, shear/slip bands, necking, etc.), and crack-dependent damage accumulation. The viewpoint we proposed is that the achieving of strength-ductility synergy depends on the delocalizing of aforementioned localized strains. Using hierarchical materials as an example, the design of heterogeneous structure significantly influences the strain delocalization behaviors in terms of internal stress/strain (elastic stage), local strain evolution (plastic stage), and cracking (fracture stage). Relationships among the heterogeneous microstructure, microscopic stress/strain evolution, macroscopic mechanical properties are established. In particular, we assess their influences on strain delocalization from the perspective of slip transfer, plastic stability, damage micromechanics, and crack propagation. A methodological framework is then suggested to understand the materials behaviors in the future using the rapidly developed physics-based multi-dimensional computational models and advanced in situ strain characterization techniques. Innovations towards excellent strength-ductility synergy and expanding applications are increasingly advocated, through promoting strain delocalization and indentifying the current challenges and future opportunities.