Production of a Non-Stoichiometric Nb-Ti HSLA Steel by Thermomechanical Processing on a Steckel Mill

Obtaining high levels of mechanical properties in steels is directly linked to the use special forming processes and addition alloying elements during their manufacture. This work presents a study hot-rolled steel strip produced achieve yield strength above 600 MPa, using niobium microalloyed HSLA with non-stoichiometric titanium (titanium/nitrogen ratio 3.42), rolled on Steckel mill. A major challenge imposed by rolling mill that process reversible, resulting long interpass times, which facilitates recrystallization grain growth kinetics. Rolling parameters whose aim was obtain maximum degree microstructural refinement were determined considering evolution simulations performed MicroSim-SM® software studying alloy through physical critical temperatures determine CCT diagram. Four ranges coiling (525–550 °C/550–600 °C/600–650 ° C/650–700 °C) applied evaluate impact microstructure, precipitation hardening, properties, results showing very refined highest observed at 600–650 °C. scenario explained carbide this temperature, leading greater contribution hardening provided presence large volume small-sized precipitates. paper shows combination optimized industrial based metallurgical mechanisms advanced modeling techniques opens up new possibilities for robust production high-strength The base stable products relies consistent size mainly effect Nb together appropriate parameters, fine TiC cooling provides additional increase reach requested values.