Strain rate-dependent hardening with dislocation-twin interaction of Fe–Mn–Al–C steel using crystal plasticity

Abstract

A crystal plasticity finite element model with dislocation-twin interaction was developed to study the strain rate-dependent hardening of Fe–Mn–Al–C twinning-induced plasticity steel. Microstructural state variables including twinning space and dislocation density were incorporated to describe the mechanical twins hindering gliding dislocations. In situ scanning electron microscope tension and electron backscatter diffraction tests were conducted as validation and supplement. Predicted stress and strain hardening rate at various strain rates agree well with the experimental results. The increasing strain hardening stage is attributed to the dynamic competition between deformation twinning and dynamic recovery of dislocations. The intergranular deformation heterogeneity associated with the competitive activities of deformation mechanisms was also studied. The results indicate a larger contribution of slip to overall hardening than twinning. GRAPHICAL ABSTRACT

Dynamic mechanical behaviour induced by adiabatic temperature rise of Fe–Mn–Al–C steel

“…We employ the classical relationship with mean dislocation density as the internal state variable so as to depict the mechanical behaviour between flow stress and true strain [12,23]:…”

“…We employ the classical relationship with mean dislocation density as the internal state variable so as to depict the mechanical behaviour between flow stress and true strain [12,23]: where α = 0.4, the interaction strength between dislocations; μ = 65 GPa, the shear modulus and b = 0.25 nm, the Burgers vector, are all referred to the literature [12]. The thermally-activated stress at the first two terms represents the friction stress of solid solution on dislocation migration due to local obstacle action [24].…”

Unified Modelling of Flow Stress and Microstructural Evolution of 300M Steel under Isothermal Tension

“…Xu et al [12] developed a modified kinetic equation to predict the SRX softening behavior of 12Cr rotor steel. Su et al [13] modelled the dislocation density evolution of Fe-Mn-Al-C steel in tension, and accurately predicted the flow stresses. Considering the glide and climb of dislocations, Surya et al [14] predicted the flow stresses in 304 HCu steel in high temperature stretching.…”