Origin and dispersion strengthening of carbonitrides in a commercial hot strip microalloyed niobium steel

Throughout this work, a study on niobium carbonitrides formation and its ha rdening effect in a commercial hot strip microalloyed steel is presented. O ptic and electron micrographs were obtained while mechanical tests and indi rect models allow to predict samples yield strength, taking into account th e steel composition and its structural characteristics. The results showed an extended precipitation on austenite boundary cells during the last therm omechanical processing stages; which probably achieved a considerable contr ibution to the hardening by dispersion in the material studied. Otherwise, no evidence of precipitation in ferrite by means of transmission electron m icroscopy (TEM) was observed. A poor interphase precipitation was detected in about 10 per cent of the total observed zones with no appreciated contri bution to the steel hardness.