Microstructure, texture, grain boundary characteristics and mechanical properties of a cold rolled and annealed ferrite-bainite dual phase steel

The microstructural, textural evolution and changes in grain boundary character distribution during annealing of a prior cold worked (30%, 50% and 80%) ferrite-bainite dual phase steel have been studied and correlated with mechanical properties. It has been shown that submicron sized subgrains can be obtained by selecting the appropriate amount of cold rolling and annealing cycle. Increasing the annealing temperature in all the materials produces the expected results, namely decrease in strength with a simultaneous increase in ductility. Although reasonably sharp gamma-fibres were obtained in 80% cold rolled and its 500 degrees C annealed counterpart, the very low (r) over bar values (<1.0) make the steel unsuitable for the purpose of deep drawing. It is envisaged that grain boundary engineering may lead to better strength-ductility combinations in this steel for an enhanced range of applications.