Abstract: In the present investigation, the effects of thermomechanical processing parameters and the steel chemical composition on the ultra fine ferrite formation characteristics were studied. This was programmed relying on the capabilities of strain induced transformation (SIT) phenomenon and applying to different grades of Si-Mn TRIP (Transformation Induced Plasticity) steels. Accordingly, wedge shaped specimens were rolled at two different temperatures, above and below the austenite-to-ferrite transformation temperature (Ar3). An ultra fine ferrite grain size, in the scale of some hundred nanometers, was obtained by rolling the specimens with lower Si content at a temperature below the related Ar3 temperature. The amount of reduction, which was resulted in the latter microstructure, was realized to be about 55%.

Keywords: UFF, SIT, TRIP, Wedge Test, Ferrite, Bainite, Single Pass Rolling.