Caracterización de la transformación de austenita deformada y no deformada en un acero C-Mn microaleado con niobio

The determination of transformation diagrams under continuous cooling conditions (CCT diagrams) is of vital importance in order to optimise the rolling sequences in order to obtain an optimal combination of mechanical properties (strength and toughness) in the products. On this matter, the effect that accumulated deformation in austenite could have on the transformation kinetics must be taken into account. With this in mind, dilatometry tests were carried out under two pre-transformation conditions: recrystallised and deformed austenite. From these tests, the CCT diagrams of both previous austenite conditions were determined. The results indicate an increase in the austenite-ferrite transformation temperature for austenite with accumulated deformation with respect to the recrystallised austenite. This displacement of the Ar3 temperature towards higher values increases for certain applications, such as in the case of sheet metal rolling, increasing the probabilities of the last rolling pass take place at the intercritical region, which could have a significant effect on the microstructure and properties of the final product.