Unraveling the Micromechanisms of Plastic Synergy in TWIP Steel With a Multigradient Structure

Gradient structural design offers a novel and effective strategy to overcome the long‐standing strength‐ductility trade‐off in metallic materials. In the present study, to address the low yield strength of conventional twinning induced plasticity (TWIP) steel, a multigradient structured (MGS) TWIP steel was developed via the combination of asynchronous rolling (AR) and subsequent annealing treatment. The as‐prepared MGS‐TWIP steel exhibits spatial gradient distributions of grain size, dislocation density, and twin spacing along the thickness direction. Result indicate that the yield strength of the MGS‐TWIP steel increases significantly with the increase in AR reduction. Statistical analyses confirm that the gradient structure enables a superior synergistic improvement in both strength and ductility. During plastic deformation, the surface layer—characterized by a higher initial dislocation density—primarily contributes to the enhanced yield strength, achieving an approximately twofold increase. In contrast, the center region, which undergoes approximately nine‐fold dislocation multiplication, plays a dominant role in enhancing strain hardening capacity and ductility. The synergistic interaction between these gradient regions provides an effective framework for achieving optimized strength‐ductility combinations in advanced structural materials.