INFLUENCE OF MICROALLOY TYPE AND CONTENT ON INDUCED PRECIPITATION KINETICS IN MICROALLOYED STEELS

Using torsion tests, and applying the back extrapolation method, the s tatically recrystallized fraction has been determined for low carbon m icroalloyed steels with different V, Nb and Ti contents, at different temperatures and an equivalent strain of 0.20%. At temperatures below the static recrystallization critical temperature (SRCT), or the tempe rature at which strain induced precipitation commences, recrystallized fraction against time curves show a plateau caused by precipitations. The formation of the plateau makes it possible to evaluate precipitat ion-time-temperature (PTT) diagrams, and thus to know the precipitatio n kinetics. The PTT diagrams show that an increase in the microalloy c ontent raises SRCT and reduces incubation time. For similar Nb, V and Ti contents, Nb is the element which raises SRCT the most.