Dependence of tensile deformation of twinning-induced plasticity steel on temperature

Abstract

• Investigating the mechanical behaviors and underlying micromechanics in TWIP steels. • Profuse deformation twins are introduced in TWIP steel at cryogenic temperature. • The cross GBs and TBs provide an easy mean for cracking in TWIP steel. We study the tensile deformation behaviour and microstructure evolution of twinning-induced plasticity (TWIP) steel at room and cryogenic temperatures. The TWIP steel shows the higher strain hardening capability, excellent strength and obvious ductility loss at cryogenic temperature. The TWIP steel has excellent strength at cryogenic temperature due to the synergistic effect of dislocation slip and deformation twinning. High-density nanotwin structure can cause strong strain hardening capability. In general, strong strain hardening leads to uniform plastic deformation, which provides high ductility. According to the microstructure characterization, the intersecting position of high-density twin-grain and twin-twin boundaries act as the nucleation sites for nanovoids, which were formed by dislocation pile up. Therefore, its ductility reduced at cryogenic temperature even with continuous steady strain hardening.