MICROSTRUCTURAL EVALUATION AND CONTINUOUS COOLING TRANSFORMATION OF A MEDIUM CARBON MICROALLOYED STEEL

The aim of this work was to study the phase transformation phenomena in a medium carbon microalloyed steel by using the dilatometry technique. This technique allows the construction of a diagram, usually denominated CCT (Continuous Cooling Transformation). At the same time, scanning electronic microscopy studies were accomplished for the characterization of the microstructures obtained. The study showed that for low cooling rates, below 1 o C/s, the transformation resulted is a predominantly pearlitic microstructure. For intermediary cooling rates (from 3 o C/s to 10 o C/s), a mixed microstructure containing pearlite and bainite was observed. Finally, at higher cooling rates (from 30 o C/s to 70 o C/s) the transformation was completed with predominantly martensitic microstructure.