Dynamic recrystallization behavior and numerical simulation of 2209 duplex stainless steel

A dynamic recrystallization model was established and finite element simulation was carried out using deform software to compare and analyze the recrystallization law under different working conditions. The results indicate high temperature, low strain rate, and large deformation lead to higher recrystallization volume fractions and larger grain sizes. Microscopic experiments reveal that elevated temperatures provide sufficient energy for dynamic recrystallization (DRX). At the same time, low strain rates offer more time for dislocation rearrangement and grain boundary migration, both of which promote DRX nucleation and contribute to grain growth. As deformation progresses, the grains gradually become more equiaxed. The experimental results are in excellent agreement with the finite element simulation outcomes. To further elucidate the evolution mechanism of dynamic recrystallization in duplex stainless steel, electron backscatter diffraction (EBSD) analysis was performed. At 950 degrees C, a subcrystalline, dynamically recrystallized structure with a high density of small angular grain boundaries was observed within the ferrite grains. However, the austenite phase hardly undergoes dynamic recrystallization, with dislocations primarily eliminated through dynamic recovery (DRV). As the temperature increases to 1100 degrees C, the orientation difference within the austenite phase increases significantly, leading to grain refinement and the formation of a small number of Sigma 3 twin boundaries. This behavior is consistent with the continuous dynamic recrystallization (CDRX) mechanism. When the strain rate is reduced to 0.01 s-1, a significant number of new Sigma 3 twin boundaries form within the austenite phase. Twinning alters the crystal orientation, transitioning the softening mechanism of the austenite phase from CDRX to discontinuous dynamic recrystallization (DDRX).