This study used the Gleeble 3800 thermomechanical simulator to examine the hot deformation characteristics of AISI 8822H steel. The main goal was to understand the alloy’s behaviour under various thermomechanical settings, emphasising temperature ranges between 1173 K and 1323 K and strain rates from 0.01 s⁻¹ to 10 s⁻¹. This study aimed to enhance the alloy’s manufacturing process by offering a thorough understanding of the material’s response to these conditions. Four various constitutive models—Arrhenius-type, Johnson–Cook, modified Johnson–Cook, and Trimble—were used in a comprehensive technique to forecast flow stress values in order to meet the study’s goals. The accuracy of each model in forecasting the behaviour of the material under the given circumstances was assessed. A thorough comparison investigation revealed that the Trimble model was the most accurate model allowing prediction of material behaviour, with the maximum correlation factor (R = 0.99) and at least average absolute relative error (1.7%). On the other hand, the Johnson–Cook model had the least correlation factor (R = 0.92) and the maximum average absolute relative error (32.2%), indicating that it was the least accurate because it could not account for all softening effects.

Two low‐C CrNiMnMoB ultrahigh‐strength steels, one Nb‐free (0Nb) and one microalloyed with 0.04 wt.% Nb (4Nb), were developed to investigate the role of Nb in hot deformation behaviour, strain‐induced precipitation, and microstructural evolution. Isothermal single‐hit compression tests were conducted over 850–1250 °C and strain rates of 0.01–50 s ⁻¹ using a Gleeble 3800 simulator, complemented by Thermo‐Calc predictions and EBSD/TEM analyses. Nb addition significantly modified the thermomechanical response by increasing flow resistance, delaying dynamic recrystallization (DRX), and elevating the deformation activation energy. Processing maps revealed that Nb shifted DRX domains toward higher temperatures and lower strain rates while suppressing regions of flow instability. Quantitative precipitation‐kinetics analysis demonstrated that the solubility of Nb in austenite is negligible at 850 °C (≈0.00049 wt.%) and increases progressively with temperature, reaching full dissolution (≈100% of total Nb, 0.04 wt.%) at 1250 °C. Increasing strain rate significantly suppressed strain‐induced NbC precipitation, reducing the normalized precipitation fraction ( X _p ) from nearly 50% at 0.01 s ⁻¹ to below ~10% at 1 s ⁻¹ and 3%–5% at 50 s ⁻¹ . These results confirm that NbC precipitation is strongly temperature‐ and strain‐rate‐dependent and governs hot deformation resistance in Nb‐microalloyed CrNiMnMoB steels.