| Summary: | In the present investigation, the non-recrystallization temperature (T<sub>NR</sub>) of niobium-microalloyed steel is determined to plan rolling schedules for obtaining the desired properties of steel. The value of T<sub>NR</sub> is based on both alloying elements and deformation parameters. In the literature, T<sub>NR</sub> equations have been developed and utilized. However, each equation has certain limitations which constrain its applicability. This study was completed using laboratory-grade low-carbon Nb-microalloyed steels designed to meet the API X-70 specification. Nb- microalloyed steel is processed by the melting and casting process, and the composition is found by optical emission spectroscopy (OES). Multiple-hit deformation tests were carried out on a Gleeble<sup>®</sup> 3500 system in the standard pocket-jaw configuration to determine T<sub>NR</sub>. Cuboidal specimens (10 (L) × 20 (W) × 20 (T) mm<sup>3</sup>) were taken for compression test (multiple-hit deformation tests) in gleeble. Microstructure evolutions were carried out by using OM (optical microscopy) and SEM (scanning electron microscopy). The value of T<sub>NR</sub> determined for 0.1 wt.% niobium bearing microalloyed steel is ~ 951 °C. Nb- microalloyed steel rolled at T<sub>NR</sub> produce partially recrystallized grain with ferrite nucleation. Hence, to verify the TNR value, a rolling process is applied with the finishing rolling temperature near TNR (~951 °C). The microstructure is also revealed in the pancake shape, which confirms T<sub>NR</sub>.
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