Beside to the effect of silicon and aluminum in suppressing the cementite formation, they have stabilized the ferrite formation. By utilizing this fact, it is suggested to obtain various combinations of micro-phases which bear a great enhancement to the medium carbon steel. The effect of silicon and aluminum has been studied on the medium carbon steel isothermal transformed by different two slow continuous cooling regimes. It was found that the enrichment of the medium carbon steel with acicular ferrite, as well as the bainite ferrite has progressively raised the strength in one hand with ductility. With certain amount of aluminum and after a slow continuous cooling rate, medium carbon steel prevails over the high alloy steel required for structure purposes from the perspective of strength and ductility.