An approach to define the effective lath size controlling yield strength of bainite

Abstract : In this study, we developed a series of fully bainitic microstructures with negligible carbide precipitation in ultra-low carbon steels. Then, we investigated the microstructure by EBSD as well as their mechanical properties. It is found that the yield stress of such bainite is proportional to the inverse lath size defined with low boundary misorientation (2–7°). We explained this by employing a theory which predicts the flow stress of deformed metals, assuming that both lath boundary and dislocation cell boundary have similar capability of being dislocation obstacles.