Effect of manganese on aging in low carbon sheet steels

For the investigation of the effect of manganese on aging in the low carbon steels the manganese content was varied from 0.02 to 0.25 wt% in the 0.02 wt% C steel. The low manganese containing steel reveals lower aging index than the high manganese steel. The aging index decreases with a decrease of manganese content and an increase of coiling temperature, because (1) the amount of solute manganese playing a role in obstructing the movement of solute carbon into the interface of carbide-ferrite, resulting in the hindrance of the carbide growth, is not sufficient and (2) the coarse carbide formed in the hot band with higher coiling temperature is crushed into small fragments during cold rolling, resulting in the development of numerous micro-voids at the fragments, which provide the numerous sites for the precipitation of solute carbon.