High dislocation density TWIP steel with an excellent combination of strength and plasticity

Abstract

After undergoing 75% hot deformation and 40% cold deformation, a variant of TWIP (Twin Induced Plasticity) steel with a composition of Fe–22Mn−2.7Al−0.95C−0.75Si (wt.%) was subjected to annealing at various temperatures (850 °C, 650 °C, 550 °C) for 20min. The recovery annealed C550 sample exhibited a yield strength of 1289.20 MPa, a tensile strength of 1442.29 MPa and an elongation of 30.78%. Characterization and comparison of the samples were conducted using XRD, SEM, EBSD, TEM and uniaxial tensile tests. The yield strength of the sample was assessed through different strengthening mechanisms to analysis the exceptional properties of the recovery annealed sample. Experimental findings indicate that the high-density dislocation and the refinement of slip bands in the recovery annealed C550 samples contribute to their superior performance compared to the partially and fully recrystallized samples.

Keywords

• TWIP
• Recovery annealing
• Dislocation density
• Yield strength