Interfaces Induced Extra Strain Hardening in Additive Manufactured Laminated Steels

Metallic alloys with heterogeneous microstructure have demonstrated superior mechanical properties, including high strength, extra work hardening and high ductility. By manipulating the thermal stability and inducing site-specific recrystallization in metal additive manufacturing, laminated 316L steels have been recently printed with various lamella structures and phase compositions, demonstrating extra strain hardening and high ultimate strength under tensile loading. We present a theoretical and numerical study on the flow behavior of the laminated structure by considering the strengthening effects of the interface affected zone. It is shown collectively from the experiments and simulations that extra back stress is developed in the interface affected zone during the deformation process, and the magnitude of this extra back stress changes with the lamella structure. Our work provides new understandings of the deformation mechanism in the heterogeneous alloys and demonstrates the potential of engineering the interfaces for enhanced mechanical properties.