Influence of electroshock treatment on microstructure and mechanical properties of as-quenched ultra-high strength hot-stamped steel

To address the "strength-ductility trade-off" in the engineering applications of ultra-high strength hot-stamped steels, this study innovatively introduces electroshock treatment (EST) applied to quenched hot-stamped samples, achieving simultaneous enhancement of strength and ductility. This study focuses on hot stamping steel and investigates the effects of EST on its microstructure and underlying mechanisms using EBSD, XRD, and TEM. Under EST conditions of 70 A/mm 2 and 300 ms, the samples achieved a tensile strength of 2023 MPa, an elongation of 9.1%, and a strength-ductility product of 18.3 GPa·%, representing improvements of 5%, 36%, and 43%, respectively, over conventional hot stamping. Multi-scale characterization revealed that EST promotes dislocation motion, thereby reducing internal stresses from dislocation entanglement. Annihilation and reorganization of dislocations at martensite lath boundaries and cementite interfaces led to homogenized stress distribution and substantially reduced lattice distortion, which significantly improved ductility. Furthermore, the supersaturated martensitic matrix underwent recovery, wherein carbon atoms dissolved and precipitated as Cottrell atmospheres or fine ε-Fe 2-3 C carbides. The interaction of these carbides with high-density dislocations enhances the overall strength-ductility balance.