Microstructure and texture formation in high strength cold rolled and annealed sheet and their correlation with formability property

A comprehensive understanding was developed on the evolution of microstructure and texture during annealing of Nb bearing microalloyed drawing quality high strength cold rolled (HSCR) sheet with specific reference to cold rolling and annealing practices. Further, this study aimed at establishing the best combination of these processing parameters to achieve an YET value of 1.4 min. For a hot rolled microstructure of moderately coarse ferrite grain of size 16 µm, it was observed that 70% cold reduction guaranteed high intensity of (222) component accompanied with minimum intensity of (200) component. Further, investigation was carried out to understand the influence of annealing time on recrystallization behavior and texture development during intermediate annealing of 60% and 70% cold reduced specimens at 550 °C. It was found that recrystallization ceased after 12 h of intermediate annealing at 550 °C. The textures and microstructures produced during final annealing of 70% cold rolled specimens at various temperatures like 670, 690, 710, and 730 °C with varied duration of soaking (12–18 h) were critically examined. An YET value of ∼1.5 was achieved in HSCR microalloyed steel when 70% cold rolled specimens were intermediately annealed at 550 °C for 12 h followed by final annealing at 710 °C for 12 h.