Microstructural Evolution Predictions Using Microsim-PM for HSLA Steels

Abstract

The simulation results for the E250 B0, S355J2, and X70M grades provide valuable insights into the effects of material thickness, deformation, and alloying elements on strain accumulation and microstructural evolution during the rolling process. For E250 B0, the low recrystallization temperature and minimal alloying led to moderate strain accumulation, with the highest reductions occurring above the RLT. In contrast, S355J2, with the addition of Nb, exhibited increased strain accumulation due to the precipitation of Nb(C,N), which enhanced the material's resistance to deformation, especially in thinner specimens. The X70M grade, with a higher Nb content, demonstrated a more pronounced strain accumulation, particularly in the thicker specimens, due to the reduced recrystallization and the influence of strain-induced precipitation. Thinner specimens experienced more intense deformation and faster recrystallization, resulting in finer grains and higher strain accumulation. Meanwhile, thicker specimens underwent slower deformation and recrystallization, promoting grain growth and reducing strain accumulation. The study highlights the critical role of material composition, thickness, and processing parameters in controlling strain accumulation, microstructural homogeneity, and the final properties of the rolled products. The presence of Nb was particularly influential in improving strain resistance and refining the microstructure, which is essential for achieving optimal material performance.