INFLUENCE OF STRAIN ON INDUCED PRECIPITATION KINETICS IN MICROALLOYEDSTEELS

Using torsion tests and applying the back extrapolation method, the st atically recrystallized fraction of low carbon microalloyed steels con taining vanadium, niobium and titanium, respectively, has been determi ned for different temperatures and strains. From the recrystallized fr action against time curves it is possible to draw precipitation-time-t emperature (PTT) diagrams. These diagrams show that the strain does no t affect precipitation kinetics in an independent manner, but that thi s influence is related with the microalloy content. The greater the st rain applied, the shorter the incubation time of induced precipitation , but this influence diminishes as the microalloy content increases. I t is also demonstrated that the incubation lime is practically indepen dent of the nature of the metal microalloy (V, Ti, Nb). In this sense, new expressions are proposed to relate the incubation and precipitati on end times with the strain and the microalloy content. A model is al so established for precipitation kinetics at the curve nose temperatur e.