Steels with ultrafine grained structure may present superplastic behavior at specific temperatures and strain rates that allow the grain boundary sliding mechanisms to be activated. The work presents high temperature tension tests in a low carbon, low alloy steel obtained by advanced thermomechanical controlled rolling processes, showing at 800°C elongations as high as 200%. The microstructure of the steel was analyzed in order to identify ferrite and pearlite grain boundaries, and their interaction after the specimens were deformed, showing intergranular decohesions, restored ferrite grains and elimination of banded structure, which are evidence of superplastic mechanisms in this material which is, in fact, ultrafine grained as demonstrated by quantitative metallographic techniques and grain size distribution analysis.
