Effect of coiling temperature on recrystallization annealing in titanium microalloyed cold-rolled steel

Abstract Through optical microscopy (OM) and transmission electron microscopy (TEM) characterization combined with hardness and tensile tests, the effects of 450°C and 600°C coiling temperatures on the annealing recrystallization behavior and mechanical properties of titanium microalloyed cold-rolled high-strength steel were systematically studied. The results show that compared to 450°C coiling, 600°C coiling reduces the recrystallization start temperature by 20°C, and under the same annealing conditions, it increases the volume fraction of recrystallized ferrite while refining the grain size. TEM analysis reveals that the TiC particles precipitated during the annealing stage of the 450°C coiled specimens are smaller, exerting a stronger pinning effect on the nucleation of recrystallized ferrite grains, resulting in the higher recrystallization temperature. However, the TiC particles precipitated during the 600°C coiling stage are coarser and inhibit ferrite grain boundary migration during annealing, leading to the refined recrystallized ferrite grains. After the process optimization involving the hightemperature coiling and the partial recrystallization annealing, the experimental steel achieved a favorable strength-ductility balance with a yield strength greater than 900 MPa and elongation greater than 12%, providing process guidance for the engineering application of titanium microalloyed cold-rolled steels.