Superior strength-ductility synergy achieved by synergistic strengthening and strain delocalization in a gradient-structured high-manganese steel

Here the combination of synergistic strengthening and strain delocalization effects is realized in high-manganese steel by gradient microstructure designing, which results in an excellent strength-ductility synergy. Specifically, the gradient structure consists of two gradient surface layers sandwiching a coarse-grained center. Hardness and microstructure examinations reveal that the synergistic strengthening is originated from the enhanced twinning behavior and extra work hardening in gradient layers. The formation of dispersed strain concentration bands is found in the nanostructured surface layer, which evolves steadily and undertakes large applied strain, thereby leading to delocalized straining response. The formation and stabilization mechanisms of strain concentration bands are analyzed in depth with respect to the microstructure gradient. These findings shed light on the deformation fundamentals of gradient structure, especially on the hetero-deformation induced effects.

Automated summary

The combination of synergistic strengthening and strain delocalization effects in high-manganese steel is achieved through gradient microstructure designing, resulting in excellent strength-ductility synergy. The enhanced twinning behavior and extra work hardening in the gradient layers contribute to the synergistic strengthening, while dispersed strain concentration bands in the nanostructured surface layer play a key role in the delocalized straining response. These findings provide insights into the deformation fundamentals of gradient structure, particularly the effects induced by hetero-deformation.